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1

Technetium radiodiagnostic fatty acids derived from bisamide bisthiol ligands  

DOEpatents

A bisamide-bisthiol ligand containing fatty acid substituted thiol useful for producing Tc-labelled radiodiagnostic imaging agents is described. The ligand forms a complex with the radionuclide .sup.99m Tc suitable for administration as a radiopharmaceutical to obtain images of the heart for diagnosis of myocardial disfunction.

Jones, Alun G. (Newton Centre, MA); Lister-James, John (Wellesley, MA); Davison, Alan (Needham, MA)

1988-05-24

2

Exposure influences expressive timing judgments in music.  

PubMed

This study is concerned with the question whether, and to what extent, listeners' previous exposure to music in everyday life, and expertise as a result of formal musical training, play a role in making expressive timing judgments in music. This was investigated by using a Web-based listening experiment in which listeners with a wide range of musical backgrounds were asked to compare 2 recordings of the same composition (15 pairs, grouped in 3 musical genres), 1 of which was tempo-transformed (manipulating the expressive timing). The results show that expressive timing judgments are not so much influenced by expertise levels, as is suggested by the expertise hypothesis, but by exposure to a certain musical idiom, as is suggested by the exposure hypothesis. As such, the current study provides evidence for the idea that some musical capabilities are acquired through mere exposure to music, and that these abilities are more likely enhanced by active listening (exposure) than by formal musical training (expertise). PMID:19170488

Honing, Henkjan; Ladinig, Olivia

2009-02-01

3

Astronomer proposal tool exposure time calculator  

NASA Astrophysics Data System (ADS)

The Astronomer Proposal Tool (APT) Exposure Time Calculator (ETC) is a generic Java library for performing ETC calculations. Currently it is primarily used by the web based ETCs supporting Hubble Space Telescope (HST) proposals at Space Telescope Science Institute (STScI). This paper describes the software architecutre, current and potential uses of this library.

McLean, Donald F.; Busko, Ivo

2004-09-01

4

Exposure Influences Expressive Timing Judgments in Music  

ERIC Educational Resources Information Center

This study is concerned with the question whether, and to what extent, listeners' previous exposure to music in everyday life, and expertise as a result of formal musical training, play a role in making expressive timing judgments in music. This was investigated by using a Web-based listening experiment in which listeners with a wide range of…

Honing, Henkjan; Ladinig, Olivia

2009-01-01

5

Time exposure of Gemini 10 launch.  

NASA Technical Reports Server (NTRS)

The Gemini 10 spacecraft is launched from Complex 19 at 5:20 p.m., July 18, 1966. A time exposure creates the illusion of multiple rocker arms. Onboard are astronauts John W. Young and Michael Collins, command pilot and pilot, respectively.

1966-01-01

6

HST Cycle 19 Exposure Time Calculators  

NASA Astrophysics Data System (ADS)

The Exposure Time Calculator (ETC) is a web-based application to assists users in calculating the exposure time needed for their HST observations, or the Signal-to-Noise Ratio (SNR) that can be achieved with a given HST observing time. These quantities are key for the preparation of proposals and observations during Phase I and Phase II of the proposing cycle and therefore must be sufficiently accurate for each of the supported observing modes of all the HST instruments. Developing a general tool that shares commonality among the different instruments is complicated, not only from the point of view of attaining accuracy of the calculations but also regarding reliability, portability, and maintainability. We are currently in the final stages of the development of the new ETC for Cycle 19 in Python. This new version improves these qualities and meets the needed level of reliability for the ETC. It also provides a basis for JWST ETCs which are in preliminary development, with a limited-functionality prototype planned to be available in Spring 2011. This papers shows the new tool, its improvements over the previous ETC and the current status of the new version.

Diaz, R. I.; Busko, I.; Greenfield, P.; Miller, T.; Sienkiewicz, M.; Sosey, M.; Laidler, V. G.

2010-07-01

7

The WFIRST Galaxy Survey Exposure Time Calculator  

NASA Technical Reports Server (NTRS)

This document describes the exposure time calculator for the Wide-Field Infrared Survey Telescope (WFIRST) high-latitude survey. The calculator works in both imaging and spectroscopic modes. In addition to the standard ETC functions (e.g. background and SN determination), the calculator integrates over the galaxy population and forecasts the density and redshift distribution of galaxy shapes usable for weak lensing (in imaging mode) and the detected emission lines (in spectroscopic mode). The source code is made available for public use.

Hirata, Christopher M.; Gehrels, Neil; Kneib, Jean-Paul; Kruk, Jeffrey; Rhodes, Jason; Wang, Yun; Zoubian, Julien

2013-01-01

8

Effects of Graduated Exposure with Feedback of Exposure Times on Snake Phobias  

ERIC Educational Resources Information Center

The subject-controlled graduated exposure of a snake with feedback of exposure times resulted in significantly less avoidance behaviors for snake-phobic subjects than for control snake-phobic subjects who did not receive therapy. (Author)

Becker, Horst G.; Costello, C. G.

1975-01-01

9

MEASUREMENT AND DECOMPOSITION OF TOTAL EXPOSURE USING THE TOTAL-ISOLATED-BY-MICROENVIRONMENT-EXPOSURE (TIME) MONITOR  

EPA Science Inventory

This paper describes a new, highly compact and lightweight monitor that directly measures personal exposure resolved into four microenvironments. he device is the "Total-Isolated-by-Microenvironment-Exposure (TIME)" monitor. he monitor can identify electronically a subject's micr...

10

Acoustic trauma effects from doubling the exposure time  

Microsoft Academic Search

Guinea pigs were exposed to 20 kHz for a period of 1 or 2 h, with and without an intermediate recovery period. Statistically smaller areas of damage were obtained after doubling the exposure time, especially without a recovery period. For a double exposure with a recovery period the areas of damage were the same as for the single exposures.

A. Pye

1979-01-01

11

Real time chemical exposure and risk monitor  

DOEpatents

The apparatus of the present invention is a combination of a breath interface and an external exposure dosimeter interface to a chemical analysis device, all controlled by an electronic processor for quantitatively analyzing chemical analysis data from both the breath interface and the external exposure dosimeter for determining internal tissue dose. The method of the present invention is a combination of steps of measuring an external dose, measuring breath content, then analyzing the external dose and breath content and determining internal tissue dose. 7 figs.

Thrall, K.D.; Kenny, D.V.; Endres, G.W.R.; Sisk, D.R.

1997-07-08

12

Adult Lead Exposure: Time for Change  

PubMed Central

We have assembled this mini-monograph on adult lead exposure to provide guidance to clinicians and public health professionals, to summarize recent thinking on lead biomarkers and their relevance to epidemiologic research, and to review two key lead-related outcomes, namely, cardiovascular and cognitive. The lead standards of the U.S. Occupational Safety and Health Administration are woefully out of date given the growing evidence of the health effects of lead at levels of exposure previously thought to be safe, particularly newly recognized persistent or progressive effects of cumulative dose. The growing body of scientific evidence suggests that occupational standards should limit recent dose to prevent the acute effects of lead and separately limit cumulative dose to prevent the chronic effects of lead. We hope this mini-monograph will motivate renewed discussion of ways to protect lead-exposed adults in the United States and around the world.

Schwartz, Brian S.; Hu, Howard

2007-01-01

13

Time series analysis of personal exposure to ambient air pollution and mortality using an exposure simulator  

PubMed Central

This paper describes a modeling framework for estimating the acute effects of personal exposure to ambient air pollution in a time series design. First, a spatial hierarchical model is used to relate Census tract-level daily ambient concentrations and simulated exposures for a subset of the study period. The complete exposure time series is then imputed for risk estimation. Modeling exposure via a statistical model reduces the computational burden associated with simulating personal exposures considerably. This allows us to consider personal exposures at a finer spatial resolution to improve exposure assessment and for a longer study period. The proposed approach is applied to an analysis of fine particulate matter of <2.5 ?m in aerodynamic diameter (PM2.5) and daily mortality in the New York City metropolitan area during the period 2001–2005. Personal PM2.5 exposures were simulated from the Stochastic Human Exposure and Dose Simulation. Accounting for exposure uncertainty, the authors estimated a 2.32% (95% posterior interval: 0.68, 3.94) increase in mortality per a 10 ?g/m3 increase in personal exposure to PM2.5 from outdoor sources on the previous day. The corresponding estimates per a 10 ?g/m3 increase in PM2.5 ambient concentration was 1.13% (95% confidence interval: 0.27, 2.00). The risks of mortality associated with PM2.5 were also higher during the summer months.

Chang, Howard H.; Fuentes, Montserrat; Frey, H. Christopher

2013-01-01

14

Gated MCP framing camera with 60-ps exposure time  

NASA Astrophysics Data System (ADS)

High voltage pulse of 140 ps in width and 2.7 kV was generated to gate the multiframe images on a meander shape microstripline on MCP. The measurement time range was extended to 1.1 ns while the exposure time of each image is 60 ps. The measured spatial resolution of the framing camera is 25 lp/mm. New method to reduce the exposure time down to 10 ps was simulated numerically.

Chang, Zenghu; Shan, Bing; Liu, Xiouqin; Liu, Jinyuan; Zhu, Wenhua; Yang, Hongru; Ren, Y. A.; Gong, Maixia

1995-09-01

15

Implementation of the STIS Exposure Time Calculator on the WWW  

NASA Astrophysics Data System (ADS)

A user-friendly WWW interface to calculate exposure times for STIS spectroscopic observations is now available. This report describes the design criteria and implementation of the WWW pages which use the expected STIS sensitivities to estimate exposure times. The Exposure Time Calculator also determines local and global count rates and S/N. The software description includes the interface between the WWW form and the calculation routines and supports debugging of revisions and updates. The support files necessary for maintaining the form and the output products from the calculations are described. The ETC can be accessed via URL http://www.stsci.edu/ftp/instrument_news/ STIS/topstis.html.

Hack, W.; Sahu, K.; Kinney, E.; Bohlin, R.

1996-10-01

16

Advantages of Real-Time Data Acquisition for Exposure Assessment  

Microsoft Academic Search

A computerized data acquisition system, utilizing real-time instrumentation and a video taping system, can provide the information necessary to identify the sources or activities which most affect worker exposure levels. Integrated workplace samplers, such as pumps with filters or charcoal tubes, may indicate a certain level of exposure. However, due to the complexity of the process or work cycle, an

Michael G. Gressel; William A. Heitbrink; James D. McGlothlin; Thomas J. Fischbach

1988-01-01

17

The WFC3 Exposure Time Calculators:Functionality and Operations  

NASA Astrophysics Data System (ADS)

We describe the current version of the WFC3 Exposure Time Calculators (ETCs) from an operations and user support point of view. The WFC3 ETCs consist of two independent engines,one for the ultraviolet/visible (UVIS) channel and one for the infrared (IR) channel. The ETCs rely upon the IRAF STSDAS SYNPHOT task COUNTRATE as the basis for their signal-to-noise and exposure time calculations.

Hanley, Christopher; Lisse, Carey; Knezek, Patricia; Lupie, Olivia; Robberto, Massimo; Nelan, Jenica

2000-07-01

18

Formaldehyde personal exposure measurements and time weighted exposure estimates in children.  

PubMed

Residential concentrations of formaldehyde have been associated with poor respiratory health in children, where formaldehyde has been measured using stationary monitors inside homes. Although children spend most of their time indoors at home, there are few studies of children's personal exposure to formaldehyde. The aim of this study was to investigate the relationship between personal exposure formaldehyde concentrations, microenvironmental concentrations and time weighted exposure estimates in children. Forty-one primary school children (aged between 9 and 12 years) wore a personal passive sampler over two 24h periods in two seasons and completed 24h daily activity diaries and a questionnaire about lifestyle and behaviour. Samplers were co located indoors at home, outdoors at centralised locations and indoors at school for the corresponding period. Personal exposure formaldehyde concentrations in this group of children were generally low with a geometric mean concentration of 9.1 ppb (range exposure concentrations and both domestic indoor (r(s)=.779, p<0.001) and time weighted estimated (r(s)=.802, p<0.001) concentrations. The time weighted model did not improve the estimate of personal exposure compared with stationary indoor concentrations. Indoor air concentration measured with a single stationary monitor was a suitable surrogate for personal exposure. PMID:22516208

Lazenby, Victoria; Hinwood, Andrea; Callan, Anna; Franklin, Peter

2012-08-01

19

Effects of carbaryl on green frog (Rana clamitans) tadpoles: Timing of exposure versus multiple exposures  

USGS Publications Warehouse

The majority of studies on pesticide impacts have evaluated the effects of single exposures. However, multiple exposures to a pesticide may be more prevalent. The objective of our study was to determine how multiple exposures versus single exposure at different times during development affected survival to metamorphosis, tadpole survival, tadpole mass, and tadpole developmental stage of green frog (Rana clamitans) tadpoles reared at low and high density in outdoor cattle tank ponds. Tadpoles were exposed to carbaryl zero, one, two, or three times at 14-d intervals. We applied single doses of carbaryl at one of three times, specifically during early, mid, or late development. Overall, we found that multiple exposures had a greater impact than single exposures during development. More individuals reached metamorphosis in ponds exposed to multiple doses of carbaryl compared with controls, indicating that the presence of carbaryl stimulated metamorphosis. The presence of carbaryl in the aquatic environment also resulted in more developed tadpoles compared with controls. Tadpoles in control ponds did not reach metamorphosis and were less developed than individuals exposed to carbaryl; this effect indicates that, under ideal conditions, green frogs could overwinter in ponds so that greater size could be attained before metamorphosis in the following spring or summer. Our study demonstrated the importance of including realistic application procedures when evaluating the effects of a pesticide and that multiple exposures to a short-lived pesticide are more likely to affect an amphibian population.

Boone, M. D.; Bridges, C. M.

2003-01-01

20

Some exposure duration effects in simple reaction time  

Microsoft Academic Search

Studied simple reaction time (RT) as a function of exposure duration in 3 successive conditions using 4 trained university students: (a) foveal stimulation-target luminance constant, (b) nonfoveal stimulation-target luminance constant, and (c) foveal stimulation-target luminance randomly but slightly varying. Evidence was found for a critical duration beyond which RT increased with exposure duration in both foveal conditions. Within the critical

Ira H. Bernstein; D. Gregory Futch; D. L. Schurman

1973-01-01

21

Correcting for Exposure Misclassification Using Survival Analysis with a Time-varying Exposure  

PubMed Central

Purpose Survival analysis is increasingly being used in perinatal epidemiology to assess time-varying risk factors for various pregnancy outcomes. Here we show how quantitative correction for exposure misclassification can be applied to a Cox regression model with a time-varying dichotomous exposure. Methods We evaluated influenza vaccination during pregnancy in relation to preterm birth among 2,267 non-malformed infants whose mothers were interviewed as part of the Slone Birth Defects Study during 2006–2011. The hazard of preterm birth was modeled using a time-varying exposure Cox regression model with gestational age as the time-scale. The effect of exposure misclassification was then modeled using a probabilistic bias analysis that incorporated vaccination date assignment. The parameters for the bias analysis were derived from both internal and external validation data. Results Correction for misclassification of prenatal influenza vaccination resulted in an adjusted hazard ratio (AHR) slightly higher and less precise than the conventional analysis: bias corrected AHR 1.04 [95% simulation interval 0.70, 1.52]; conventional AHR 1.00 [95% confidence interval 0.71, 1.41]. Conclusion Probabilistic bias analysis allows epidemiologists to assess quantitatively the possible confounder-adjusted effect of misclassification of a time-varying exposure, in contrast to a speculative approach to understanding information bias.

Ahrens, Katherine; Lash, Timothy L.; Louik, Carol; Mitchell, Allen A.; Werler, Martha M.

2012-01-01

22

Residence and exposure times : when diffusion does not matter  

NASA Astrophysics Data System (ADS)

Under constant hydrodynamic conditions and assuming horizontal homogeneity, negatively buoyant particles released at the surface of the water column have a mean residence time in the surface mixed layer of h/ w, where h is the thickness of the latter and w ( > 0) is the sinking velocity Deleersnijder (Environ Fluid Mech 6(6):541-547, 2006a). The residence time does not depend on the diffusivity and equals the settling timescale. We show that this behavior is a result of the particular boundary conditions of the problem and that it is related to a similar property of the exposure time in a one-dimensional infinite domain. In 1-D advection-diffusion problem with a constant and uniform velocity, the exposure time—which is a generalization of the residence time measuring the total time spent by a particle in a control domain allowing the particle to leave and reenter the control domain—is also equal to the advection timescale at the upstream boundary of the control domain. To explain this result, the concept of point exposure is introduced; the point exposure is the time integral of the concentration at a given location. It measures the integrated influence of a point release at a given location and is related to the concept of number of visits of the theory of random walks. We show that the point exposure takes a constant value downstream the point of release, even when the diffusivity varies in space. The analysis of this result reveals also that the integrated downstream transport of a passive tracer is only effected by advection. While the diffusion flux differs from zero at all times, its integrated value is strictly zero.

Delhez, Éric J. M.; Deleersnijder, Éric

2012-12-01

23

Novel monitor paradigm for real-time exposure assessment.  

PubMed

A wearable monitor that can reliably, accurately, and continuously measure personal exposure levels of various toxicants would not only accelerate the current environmental and occupational health and safety studies, but also enable new studies that are not possible with the current monitoring technology. Developing such a monitor has been a difficult challenge, and requires innovative sensing science and creative engineering. We have developed, built, and tested a wearable monitor for real-time detection of toxic hydrocarbons and acids in the environment. The monitor is low-cost, accurate, and user friendly. In addition, it can communicate wirelessly with a cell phone in which the monitoring results can be processed, displayed, stored, and transmitted to a designated computer. We have validated the functions and performance of the monitor, and carried out field tests with workers involving waste management, fire overhaul, and floor-cleaning activities, as well as with first- and second-hand smokers. The averaged exposure levels are in agreement with those determined by the standard NIOSH methods. The monitor provides accurate and real-time exposure assessment for the workers involving different activities. The real-time and continuous monitoring capability makes it possible to correlate the exposure levels with different activities and changes in the microenvironments. The monitor provides unprecedented real-time information that will help advance occupational safety and environmental health studies. It may also be used to better protect workers from occupational overexposure to toxic molecules. PMID:20551996

Negi, Indira; Tsow, Francis; Tanwar, Kshitiz; Zhang, Lihua; Iglesias, Rodrigo A; Chen, Cheng; Rai, Anant; Forzani, Erica S; Tao, Nongjian

2011-01-01

24

Novel Monitor Paradigm for Real-Time Exposure Assessment  

PubMed Central

A wearable monitor that can reliably, accurately and continuously measure personal exposure levels of various toxicants would not only accelerate the current environmental and occupational health and safety studies, but also enable new studies that are not possible with the current monitoring technology. Developing such a monitor has been a difficult challenge, and requires innovative sensing science and creative engineering. We have developed, built and tested a wearable monitor for real-time detection of toxic hydrocarbons and acids in environment. The monitor is low-cost, accurate, and user-friendly. In addition, it can communicate wirelessly with a cell phone in which the monitoring results can be processed, displayed, stored and transmitted to a designated computer. We have validated the functions and performance of the monitor, and carried out field tests with workers involving waste management, fire overhaul, and floor-cleaning activities, as well as with first- and second-hand smokers. The averaged exposure levels are in agreement with those determined by the standard NIOSH methods. The monitor provides accurate and real-time exposure assessment for the workers involving different activities. The real-time and continuous monitoring capability makes it possible to correlate the exposure levels with different activities and changes in the microenvironments. The monitor provides unprecedented real-time information that will help advance occupational safety and environmental health studies. It may also be used to better protect workers from occupational overexposure to toxic molecules.

Negi, Indira; Tsow, Francis; Tanwar, Kshitiz; Zhang, Lihua; Iglesias, Rodrigo A.; Chen, Cheng; Rai, Anant; Forzani, Erica S.; Tao, Nongjian (NJ)

2013-01-01

25

Creating the Prototype JWST Exposure Time Calculators (ETCs)  

NASA Astrophysics Data System (ADS)

Exposure time calculators (ETCs) are tools that astronomers use to explore the observing scenarios for their scientific data acquisition. ETCs are heavily used during the periods of observation proposal planning and submission. They are used not only to get estimates for exposure times, but also to check on the health and safety risks those observations might pose to the telescope. The James Webb Space Telescope (JWST) is still in development and does not yet have any orbital data. However, having access to such a tool can greatly aid scientists as they discover the new capabilities that JWST will provide. Recently, the Hubble Space Telescope (HST) ETC was redesigned and we leveraged this experience and the knowledge gained to implement a prototype ETC for a limited set of JWST observing modes.

Sosey, M.; Hanley, C.; Laidler, V.; Lindsay, K.; Sienkiewicz, M.; Greenfield, P.; Barker, E.

2012-09-01

26

Time variant exposure analysis (TVEA): a measurement tool for characterizing particulate exposure determinants in construction.  

PubMed

A work sampling-based approach, time variant exposure analysis (TVEA), was developed for assessment of determinants for particulate air contaminants in dynamic construction environments. To use TVEA, the field researcher records observations at fixed intervals to systematically survey over 30 potential determinants that could affect exposure to three types of particulate matter: quartz-containing dusts, diesel exhaust, and a general grouping of "other particles" that includes welding fume and wood dust. Two field studies were conducted to address questions of inter-rater reliability (n = 20) and coding interval appropriateness (n = 21) for the TVEA method. At least substantial inter-rater agreement (kappa > 0.60) was obtained for the TVEA variables related to tool or machine use, process, material, source intensity, and source orientation. Kappa values for source direction (0.22-0.38) and number of sources (0.38-0.60) showed comparatively lower agreement for all particulate types. Observation interval appropriateness was analyzed using linear regression to compare a 5-min observation interval "gold standard" with alternate intervals. Regression statistics indicated that while 30 min is an acceptable interval for exposure assessment, 15 min optimizes precision and practicality by ensuring that 95% of all observations differ less than ten percentage points from the "true" values. TVEA is a useful exposure assessment tool for the dynamic construction environment. It is flexible in that only those determinants that are of interest need be coded and the coding interval can be adjusted to accommodate the level of precision desired. PMID:15742711

Kalil, Andrew J; Woskie, Susan R; Holcroft, Christina; Ellenbecker, Michael; Buchholz, Bryan

2004-12-01

27

Lung cancer in French and Czech uranium miners: Radon-associated risk at low exposure rates and modifying effects of time since exposure and age at exposure.  

PubMed

Radon is recognized as a public health concern for indoor exposure. Precise quantification derived from occupational exposure in miners is still needed for estimating the risk and the factors that modify the dependence on cumulated exposure. The present paper reports on relationship between radon exposure and lung cancer risk in French and Czech cohorts of uranium miners (n = 10,100). Miners from these two cohorts are characterized by low levels of exposure (average cumulated exposure of less than 60 WLM) protracted over a long period (mean duration of exposure of 10 years) and by a good quality of individual exposure estimates (95% of annual exposures based on radon measurements). The modifying effect of the quality of exposure on the risk is analyzed. A total of 574 lung cancer deaths were observed, which is 187% higher than expected from the national statistics. This significantly elevated risk is strongly associated with cumulated radon exposure. The estimated overall excess relative risk per WLM is 0.027 (95% CI: 0.017-0.043, related to measured exposures). For age at exposure of 30 and 20 years since exposure, the ERR/WLM is 0.042, and this value decreases by approximately 50% for each 10-year increase in age at exposure and time since exposure. The present study emphasizes that the quality of exposure estimates is an important factor that may substantially influence results. Time since exposure and simultaneously age at exposure were the most important effect modifiers. No inverse exposure-rate effect below 4 WL was observed. The results are consistent with estimates of the BEIR VI report using the concentration model at an exposure rate below 0.5 WL. PMID:18220460

Tomasek, Ladislav; Rogel, Agnès; Tirmarche, Margot; Mitton, Nicolas; Laurier, Dominique

2008-02-01

28

ETC-42 : A Generic, VO Compliant, Exposure Time Calculator  

NASA Astrophysics Data System (ADS)

We developed at CeSAM (Centre de donneeS Astrophysiques de Marseille) a new, Virtual Observatory compliant, Exposure Time Calculator, ETC-42. This new ETC performs an instrument-independent computation, derived from the comparison of several (instrument focused) existing ETCs, enabling it to cover a wide range of existing or future instrumentation. Its flexible design and support for plugins allows for easy addition of new computation methods, ensuring its usefulness even for future technologies or for instrumentation with specific calculation requirements. This paper describes the current calculation functionality, the interfaces used for communication with the user and it concludes with the design and frameworks used for achieving the systems flexibility and extensibility.

Apostolakos, N.; Surace, C.; Chabaud, P.-Y.; LeLeu, G.; LAM scientists

2012-09-01

29

Assessing the Impact of Exposure Time and Incapacitation on Longitudinal Trajectories of Criminal Offending.  

ERIC Educational Resources Information Center

Examined effect of accounting for exposure (incarceration) time on arrest rate of 272 paroled serious offenders followed through age 33. Analysis without exposure time adjustments suggested that over 92 percent exhibited highest arrest activity in late teens and early 20s. Adjusted for exposure time, about 72 percent showed a decline in arrest…

Piquero, Alex; Blumstein, Alfred; Brame, Robert; Haapanen, Rudy; Mulvey, Edward P.; Nagin, Daniel S.

2001-01-01

30

MODELS FOR MESOTHELIOMA INCIDENCE FOLLOWING EXPOSURE TO FIBERS IN TERMS OF TIMING AND DURATION OF EXPOSURE AND THE BIOPERSISTENCE OF THE FIBERS  

Microsoft Academic Search

The health effects of inhaled fibers are related to the intensity and duration of exposure and occur many years after the exposure. In particular, the incidence of mesothelioma after exposure to asbestos is proportional to the intensity of exposure (fibers per milli- liter of air) and the duration of exposure, and to the time that has elapsed since the exposure.

G. Berry

1999-01-01

31

[Solar time--the importance of standard time for the UV-exposure of the skin].  

PubMed

Dermatologists recommend that people avoid exposure to the blazing sun around noontime. In most places in Europe there are considerable deviations between true solar time and standard time: Firstly, during summer the standard time in the European countries is set one hour ahead according to the summer time or daylight saving time. Secondly, in all countries of Western and Central Europe, except Great Britain, Ireland and Portugal, standard time uniformly is Central European Summer Time (CEST). Although this standard central European time zone refers to the longitude 15 degrees East of Greenwich, it is valid for all longitudes up to nearly about 9 degrees West of Greenwich. This leads to a maximum deviation between standard time and solar time of nearly 1 hour and 36 min. Thirdly, a comparably small time shift is due to the equation of time. It amounts up to a maximum of about six and a half minutes at the end of July. Altogether, the shift between standard time and true solar time adds up to about 2 h 40 min at the Spanish coast of the Atlantic Ocean, e.g. noon is not at 12:00 but rather at 2:40 p. m. (14:40 h CEST).A paradoxical situation results for British holiday-makers who go to Spain. Although they move to a more westerly geographical position they do not put back their clocks but set them one hour ahead, since they enter the CEST zone. The recommendations given by dermatologists to the people regarding their exposure to the sun should allow for these geographical and astronomical facts. PMID:17760900

Stick, Carsten

2007-09-01

32

Self-reported and measured time of vibration exposure at ultrasonic scaling in dental hygienists  

Microsoft Academic Search

In the present study, our objective was to quantify the daily duration of vibration exposure from ultrasonic scaling in dental hygienists and to compare different methods of self-estimates to time-recorded measurements. The exposure time was self-estimated by use of diary and interview methods in 10 subjects. We found that the measured total daily exposure time was limited, only on average

Ingrid Åkesson; Istvan Balogh; Staffan Skerfving

2001-01-01

33

Retention of Idioms Following One-Time Exposure  

ERIC Educational Resources Information Center

This study explored retention of idioms and novel (i.e. newly created or grammatically generated) expressions in English-speaking girls following exposure only once during a conversation. Our hypothesis was that idioms, because of their inherent holistic, nonliteral and social characteristics, are acquired differently and more rapidly than novel…

Reuterskiold, Christina; Van Lancker Sidtis, Diana

2013-01-01

34

EXPOSURE DOMAINS: ROLE OF TIMING, PATTERN AND MAGNITUDE OF EXPOSURE ON HEALTH RISKS  

EPA Science Inventory

Environmental health risk assessment may be broadly separated into assessment of risks from exposures to agents affecting health endpoints for which it may be presumed there is no dose threshold, and to agents affecting endpoints that more likely have a dose threshold. For hea...

35

A wide dynamic range CMOS image sensor with multiple short-time exposures  

Microsoft Academic Search

A wide dynamic range CMOS image sensor based on synthesis of long-time and multiple short-time exposure signals for high image quality in the whole illumination range is proposed. A key technique is a high-speed and high-resolution column-parallel integration type analog-to-digital converter (ADC) with nonlinear slope. A prototype wide dynamic range CMOS image sensor that captures a long-exposure and 3 short-exposure

Masaaki Sasaki; Mitsuhito Mase; Shoji Kawahito; Yoshiaki Tadokoro

2004-01-01

36

Duration and timing of exposure to neighborhood poverty and the risk of adolescent parenthood.  

PubMed

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

Wodtke, Geoffrey T

2013-10-01

37

Population exposure to ultraviolet radiation in Finland 1920-1995: Exposure trends and a time-series analysis of exposure and cutaneous melanoma incidence  

SciTech Connect

Ultraviolet radiation (UVR) is the principal cause of cutaneous malignant melanoma (CMM). However, the relation between CMM and UVR exposure is not clear. We present the trends of population exposure to UVR and conduct a time-series analysis of the relation between UVR exposure and incidence of CMM. Data on CMM incidence were obtained from the Finnish Cancer Registry. Clothing coverage of the body was scored from archival photographs and the proportion of uncovered skin was used as a measure of solar exposure. Information on the number of sunny resort holidays, duration of annual holidays, and sunscreen sales were obtained from various sources. Exposed skin area doubled from 1920 to 1985. The average duration of annual holidays increased 30-fold. The number of sunny resort holidays and the sales of sunscreens increased rapidly from 1980. CMM was most strongly associated with solar exposure of 5-19 years earlier. There is a considerable decrease in clothing coverage during the 20th century. UVR exposure preceding CMM occurrence 4 years or less does not appear relevant, whereas the period 5-19 years prior to CMM occurrence might be the most relevant period. However, findings of ecological studies may not be applicable at the individual level.

Kojo, Katja [STUK-Radiation and Nuclear Safety Authority, 00881 Helsinki (Finland) and School of Public Health, University of Tampere, 33014 Tampere (Finland)]. E-mail: katja.kojo@uta.fi; Jansen, Christer T. [Department of Dermatology, University of Turku, 20540 Turku (Finland); Nybom, Pia [University of Art and Design, 00560 Helsinki (Finland); Huurto, Laura [STUK-Radiation and Nuclear Safety Authority, 00881 Helsinki (Finland); Laihia, Jarmo [Department of Dermatology, University of Turku, 20540 Turku (Finland); Ilus, Taina [STUK-Radiation and Nuclear Safety Authority, 00881 Helsinki (Finland); Auvinen, Anssi [STUK-Radiation and Nuclear Safety Authority, 00881 Helsinki (Finland); School of Public Health, University of Tampere, 33014 Tampere (Finland)

2006-05-15

38

The design of a miniature personal exposure monitor for continuous real-time data acquisition in electromagnetic field exposure assessment  

SciTech Connect

The design of a small, light-weight personal exposure monitor suitable for use in EMF exposure assessment studies is nearing completion at Pacific Northwest Laboratory. The monitor is designed to be non-obtrusive, battery operated, and able to continuously record extremely low-frequency (ELF) (1Ohz--500hz) magnetic-field data. It also captures high-frequency (500hz--1OMhz) transients that exceed a preset threshold, retaining the largest transients in memory. The monitor can record one or more days of data on a single easily replaceable, credit-card-size memory (PCMCIA). A battery charge will last a minimum of one day. Batteries are rechargeable and easily replaced. A data-compression algorithm is under development that will be tailored to the efficient compression of low-frequency EMF signals and will permit data to be logged for at least one day before swapping memory cards. The memory cards are readable by a base- station computer that can perform analysis of the data. The monitor is designed to accommodate four inputs supporting full-field sensors as well as a proposed ocular exposure measurement system. Our design effort has shown that a practical personal exposure monitor for EMF can be built based on current technology, continuous logging of real-time ELF waveforms is both feasible and practical, and such a device is appropriate for proposed EMF exposure studies.

Hansen, N.H.; Conroy, T.J.; Wilson, B.W.

1994-06-01

39

Nearshore subtidal bathymetry from time-exposure video images  

Microsoft Academic Search

Time-averaged (over many wave periods) nearshore video observations show the process of wave breaking as one or more white alongshore bands of high intensity. Across a known depth profile, similar bands of dissipation can be predicted with a model describing the time-averaged cross-shore evolution of organized wave and roller energy. This close correspondence between observed and modeled dissipation proxies is

S. G. J. Aarninkhof; B. G. Ruessink; J. A. Roelvink

2005-01-01

40

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 ...

41

Peritoneal Glucose Exposure and Changes in Membrane Solute Transport with Time on Peritoneal Dialysis  

Microsoft Academic Search

Peritoneal solute transport increases with time on treatment in a proportion of peritoneal dialysis (PD) patients, contributing to ultrafiltration failure. Continuous exposure of the peritoneum to hypertonic glucose solutions results in mor- phologic damage that may have a causative role in changes in peritoneal function. The purpose of this analysis was to estab- lish whether increased exposure to glucose preceded

SIMON J. DAVIES; LOUISE PHILLIPS; PATRICK F. NAISH; GAVIN I. RUSSELL

2001-01-01

42

A network-based approach for estimating pedestrian journey-time exposure to air pollution.  

PubMed

Individual exposure to air pollution depends not only upon pollution concentrations in the surrounding environment, but also on the volume of air inhaled, which is determined by an individual's physiology and activity level. This study focuses on journey-time exposure, using network analysis in a GIS environment to identify pedestrian routes between multiple origins and destinations throughout the city of Lancaster, North West England. For each segment of a detailed footpath network, exposure was calculated accounting for PM2.5 concentrations (estimated using an atmospheric dispersion model) and respiratory minute volume (varying between individuals and with slope). For each of the routes generated the cumulative exposure to PM2.5 was estimated, allowing for easy comparison between multiple routes. Significant variations in exposure were found between routes depending on their geography, as well as in response to variations in background concentrations and meteorology between days. Differences in physiological characteristics such as age or weight were also seen to impact journey-time exposure considerably. In addition to assessing exposure for a given route, the approach was used to identify alternative routes that minimised journey-time exposure. Exposure reduction potential varied considerably between days, with even subtle shifts in route location, such as to the opposite side of the road, showing significant benefits. The method presented is both flexible and scalable, allowing for the interactions between physiology, activity level, pollution concentration and journey duration to be explored. In enabling physiology and activity level to be integrated into exposure calculations a more comprehensive estimate of journey-time exposure can be made, which has potential to provide more realistic inputs for epidemiological studies. PMID:24704957

Davies, Gemma; Whyatt, J Duncan

2014-07-01

43

Nitrous oxide and occupational exposure: it's time to stop laughing.  

PubMed

Although nitrous oxide (N(2)O) has been widely used since 1844, in recent years it has been implicated in a number of serious health hazards such as reproductive, nerve, liver, and kidney disorders. The National Institute of Safety and Health (NIOSH) recommends a limit of 25 ppm for chronic exposure to N(2)O in the dental office. Our study monitored ambient N(2)O levels in the dental office. N(2)O levels were compared for procedures performed in open clinics and private operatories as well as with and without a gas-scavenging system. Measurements were taken in the Dental Breathing Zone (DBZ) and Dental Chair Foot (DCF) at regular intervals. A four- to eightfold increase in average N(2)O levels was noted in the DBZ for unscavenged versus scavenged procedures. A three- to fourfold increase for unscavenged versus scavenged procedures was similarly noted in the DCF. N(2)O were significantly higher in private operatories than in open clinics, due to limited room volumes and in the DBZ over the DCF, due to mask leakage and increased oral exhalation. Scavenged N(2)O levels for both operatory types did not meet NIOSH guidelines. In contrast to previous studies using any form of gas removal, our study shows a significant decrease in N(2)O level achieved with an adequate scavenger system. With only four states regulating the use of N(2)O, and with concern over its deleterious effects growing, additional states and the federal government are expected to enact legislation regulating the use of N(2)O in the near future. PMID:2490056

Kugel, G; Norris, L H; Zive, M A

1989-01-01

44

Nitrous Oxide and Occupational Exposure: It's Time to Stop Laughing  

PubMed Central

Although nitrous oxide (N2O) has been widely used since 1844, in recent years it has been implicated in a number of serious health hazards such as reproductive, nerve, liver, and kidney disorders. The National Institute of Safety and Health (NIOSH) recommends a limit of 25 ppm for chronic exposure to N2O in the dental office. Our study monitored ambient N2O levels in the dental office. N2O levels were compared for procedures performed in open clinics and private operatories as well as with and without a gas-scavenging system. Measurements were taken in the Dental Breathing Zone (DBZ) and Dental Chair Foot (DCF) at regular intervals. A four- to eightfold increase in average N2O levels was noted in the DBZ for unscavenged versus scavenged procedures. A three- to fourfold increase for unscavenged versus scavenged procedures was similarly noted in the DCF. N2O were significantly higher in private operatories than in open clinics, due to limited room volumes and in the DBZ over the DCF, due to mask leakage and increased oral exhalation. Scavenged N2O levels for both operatory types did not meet NIOSH guidelines. In contrast to previous studies using any form of gas removal, our study shows a significant decrease in N2O level achieved with an adequate scavenger system. With only four states regulating the use of N2O, and with concern over its deleterious effects growing, additional states and the federal government are expected to enact legislation regulating the use of N2O in the near future.

Kugel, Gerard; Norris, Lonnie H.; Zive, Marc A.

1989-01-01

45

Timing and Duration of Exposure in Evaluations of Social Programs  

Microsoft Academic Search

Impact evaluations aim to measure the outcomes that can be attributed to a specific policy or intervention. While there have been excellent reviews of the different methods for estimating impact, insufficient attention has been paid to questions related to timing: How long after a program has begun should it be evaluated? For how long should treatment groups be exposed to

Elizabeth M. King; Jere R. Behrman

2009-01-01

46

Timing and duration of exposure in evaluations of social programs  

Microsoft Academic Search

Impact evaluations aim to measure the outcomes that can be attributed to a specific policy or intervention. Although there have been excellent reviews of the different methods that an evaluator can choose in order to estimate impact, there has not been sufficient attention given to questions related to timing: How long after a program has begun should one wait before

Elizabeth M. King; Jere R. Behrman

2008-01-01

47

Estimating sampling frequency in pollen exposure assessment over time+  

PubMed Central

A time series model was fitted to the pollen concentration data collected in the Greater Cincinnati area for the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS). A traditional time series analysis and temporal variogram approach were applied to the regularly spaced databases (collected in 2003) and irregularly spaced ones (collected in 2002), respectively. The aim was to evaluate the effect of the sampling frequency on the sampling precision in terms of inverse of standard error of the overall level of mean value across time. The presence of high autocorrelation in the data was confirmed and indicated some degree of temporal redundancy in the pollen concentration data. Therefore, it was suggested that sampling frequency could be reduced from once a day to once every several days without a major loss of sampling precision of the overall mean over time. Considering the trade-offs between sampling frequency and the possibility of sampling bias increasing with larger sampling interval, we recommend that the sampling interval should take values from 3 to 5 days for the pollen monitoring program, if the goal is to track the long-term average.

Luo, Junxiang; Shukla, Rakesh; Adhikari, Atin; Reponen, Tiina; Grinshpun, Sergey A.; Zhang, Qi; LeMasters, Grace K.

2007-01-01

48

Exposure time and the effect of hexylresorcinol on bacterial aggregates.  

PubMed

The bactericidal effect of hexylresorcinol was assessed using bacterial aggregates. Increased drug concentration resulted in decreased survival of bacteria when the aggregates were exposed to hexylresorcinol for at least eight hours. This indicates that this drug may be effective against dental plaque only when available for long periods of time. PMID:292680

Kraal, J H; Hussain, A A; Gregorio, S B; Akaho, E

1979-11-01

49

Accounting for Unobservable Exposure Time Bias When Using Medicare Prescription Drug Data  

PubMed Central

Objective To describe the prevalence and correlates of unobservable medication exposure time, and to recommend approaches for minimizing bias, in studies using Medicare Part D data.. Sample 179,065 Medicare patients hospitalized for an AMI in 2007 or 2008. Methods We compared two methods for creating medication exposure observation periods using acute care discharge vs. post-acute care discharge dates. We examined options for increasing cohort sizes by requiring different thresholds for observable days, or by using as a covariate, in the observation period. We calculated the extent and health status correlates of unobserved Medicare Part D exposure time and examined its association with receipt of beta-blockers. Results 39% of patients had unobservable time during the 30 day exposure assessment period following acute care; they were significantly older, had more comorbidity and longer acute care stays, had worse 1-year survival, and were significantly less likely to be classified as beta-blocker users. Using the alternative exposure assessment window, only 29% of the sample had unobservable time, and differences between groups were less pronounced. Significant gains in sample size can be obtained by restricting or controlling for the number of observable days required in the exposure assessment period. Conclusions Unobservable exposure time is common among Medicare Part D beneficiaries, and they are often in worse health. To retain patients with unobservable exposure time, we recommend stratifying patients on receipt of post-acute facility-based care, calculating and using observable days as a covariate and, when appropriate, using the discharge date from contiguous post-acute facility care for beginning the exposure assessment period.

Cook, Elizabeth A.; Schneider, Kathleen M; Chrischilles, Elizabeth; Brooks, John M

2013-01-01

50

Pressure reduction limits for rats subjected to various time/pressure exposures.  

PubMed

The impact of the combined effects of exposure time and hydrostatic pressure on pressure reduction is explored in this study. In Phase I of the study, excursion dives were made to 10, 20, and 30 ATA for 5, 10, 20, 40, or 80 min. In Phase II, the animals were saturated at 1.3, 10, or 20 ATA for 60 min; each saturation exposure was followed by a 10-atm excursion dive of either 1, 5, 10, 20, or 40 min. The chamber gas mixture during all pressure exposures was 0.51 ATA oxygen, 0.79 ATA nitrogen, and the remainder helium. The subjects were 655 rats; during each pressure exposure 5 rats were exercised in a rotating cage. After each exposure, the rats were abruptly decompressed to a lesser pressure for observation and tabulation of the decompression sickness incidence. Results suggest that neither the starting saturation pressure nor the differential excursion pressure alters the time required for an animal to reach equilibrium with the surrounding environment. Pressure-reduction values, however, vary with both the exposure pressure and exposure time. These results will have a direct impact on the formulation of future decompression models. PMID:734800

Berghage, T E; Goehring, G S; Donelson, C

1978-12-01

51

Toxicokinetics and toxicity of zinc under time-varying exposure in the guppy (Poecilia reticulata).  

PubMed

Levels of toxic substances released into the environment are often highly variable and fluctuate over time. The present study deals with a simple type of time-variable exposure, diluted pulse. We determined toxicokinetic parameters of zinc in guppy fish (Poecilia reticulata) and evaluated the applicability of a toxicokinetics-based survival model developed earlier. In the toxicokinetics experiment, zinc was rapidly taken up and released again; the half-life in fish was only 1.5 d. In the toxicity experiments with diluted-pulse exposure, survival leveled off to a baseline level, which in accordance with the model is explained by the dilution of zinc. The model fitted reasonably well for the lower initial concentrations but tended to overestimate survival rates at the higher concentrations. Toxicokinetic parameters estimated from changes in survival were close to values estimated from measured zinc concentrations in water. Elimination rates during pulse exposure varied from 0.434 to 0.488 d(-1) and corresponded very well to the elimination rate during constant exposure (0.463 d(-1)). Ultimate LC50 values were estimated as 6.40 and 9.10 mg/L. These results suggest that toxicity experiments with a simple, time-varying exposure can be used as an alternative to conventional, constant-exposure experiments. Toxicokinetic parameters and toxicological endpoints can still be estimated in static bioassays with decreasing exposure if the concentration in the medium is measured. At the same time, diluted-pulse experiments may simulate exposure from discharges in the field better than constant-exposure experiments. PMID:11345451

Widianarko, B; Kuntoro, F X; Van Gestel, C A; Van Straalen, N M

2001-04-01

52

Research plan for establishing the effects of time varying noise exposures on community annoyance and acceptability  

NASA Technical Reports Server (NTRS)

The design of a community noise survey to determine the effects of time varying noise exposures in residential communities is presented. Complex physical and human variables involved in the health and welfare effects of environmental noise and the number-level tradeoffs and time of day penalties are among the factors considered. Emphasis is placed on community reactions where noise exposures are equal in day or evening but differ in the night time, and the effects of ambient noise on more intense aircraft noise exposures. Thirteen different times of day and types of operation situations with exposed populations up to 8-10 miles from the airport are identified. A detailed personal interview questionnaire as well as specific instructions to interviewers are included.

Borsky, P. N.

1980-01-01

53

Public bus and taxicab drivers' work-time exposure to aromatic volatile organic compounds.  

PubMed

Information on the work-time exposure of public bus and taxicab drivers to volatile organic compounds (VOCs) may be a critical factor in exploring the association between occupational exposure and health effects. Accordingly, this study evaluated the work-time VOC exposure of public bus and taxicab drivers by measurement of six selected aromatic VOC concentrations in the personal air of public bus and taxicab drivers during winter and summer. Two groups of five public bus drivers (smokers and nonsmokers) and two groups of five taxicab drivers (smokers and nonsmokers) were recruited for the study. The taxicab drivers were found to be exposed to higher aromatic compound levels than the bus drivers during their daily work time. The personal exposure of the bus and taxicab drivers was influenced by whether or not they smoked plus the season. It was also established that the potential exposure of bus drivers to aromatic VOCs did not exceed that of an unemployed reference group, whereas the potential exposure of taxicab drivers did. Meanwhile, based on comparison of the calculated in-vehicle concentrations with those from a previous study, the VOC levels inside public buses and taxicabs were found to be lower than those inside automobiles. PMID:11386743

Jo, W K; Yu, C H

2001-05-01

54

Investigating the American Time Use Survey from an Exposure Modeling Perspective  

EPA Science Inventory

This paper describes an evaluation of the U.S. Bureau of Labor Statistics' American Time Use Survey (ATUS) for potential use in modeling human exposures to environmental pollutants. The ATUS is a large, on-going, cross-sectional survey of where Americans spend time and what activ...

55

A study of the effect of nonrandom sampling on the estimation of exposure variability using exposure-time series from the OSHA IMIS health inspection database  

SciTech Connect

The objective of this study was to determine the effect of nonrandom sampling over time may have on the estimation of variability, namely the geometric standard deviation, using time series of personal exposure data.

Martinez, L.T.

1997-05-01

56

Odors: appetizing or satiating? Development of appetite during odor exposure over time.  

PubMed

Background:Exposure to palatable food odors influences appetite responses, either promoting or inhibiting food intake. Possibly, food odors are appetizing after a short exposure (of circa 1-3?min), but become satiating over time (circa 10-20?min).Objective:To investigate the effect of odor exposure on general appetite and sensory-specific appetite (SSA) over time.Design:In a cross-over study, 21 unrestrained women (age: 18-45 years; BMI: 18.5-25?kg?m(-2)) were exposed for 20?min to eight different odor types: five food odors, two nonfood odors and no-odor. All odors were distributed in a test room at suprathreshold levels. General appetite, SSA and salivation were measured over time.Results:All food odors significantly increased general appetite and SSA, compared with the no-odor condition. The nonfood odors decreased general appetite. All effects did not change over time during odor exposure. Savory odors increased the appetite for savory foods, but decreased appetite for sweet foods, and vice versa after exposure to sweet odors. Neither food odors nor nonfood odors affected salivation.Conclusions:Palatable food odors were appetizing during and after odor exposure and did not become satiating over a 20-min period. Food odors had a large impact on SSA and a small impact on general appetite. Moreover, exposure to food odors increased the appetite for congruent foods, but decreased the appetite for incongruent foods. It may be hypothesized that, once the body is prepared for intake of a certain food with a particular macronutrient composition, it is unfavorable to consume foods that are very different from the cued food. PMID:23917805

Ramaekers, M G; Boesveldt, S; Lakemond, C M M; van Boekel, M A J S; Luning, P A

2014-05-01

57

Application of real-time particulate sensors to help mitigate exposures of wildland firefighters.  

SciTech Connect

High Particulate exposures have been demonstrated to decrease lung function among firefighters. In this article, the authors demonstrated the feasibility of using small real-time particle sensors to inform wildland firefighters so they can make informed decisions on the use of personal respiratory protection. Using 1mg/m3 as an indicator point for use of appropriately designed respiratory protection, such sensors could help prevent 16% to 74% of particulate exposure prescribed burns when firefighters assess exposure as low or medium. Adherence to such a guideline for the use of respiratory protection would involve its deployment of 3% to 22% of individual shifts. In addition, sensors are a valuable tool for tracking exposure to particulates among wildland firefighters for occupational health monitoring.

Edwards, Rufus; Johnson, Michael: Dunn, Kevin H.; Naeher, Luke P.

2005-02-01

58

Application of real-time particle sensors to help mitigate exposures of wildland firefighters.  

PubMed

High particulate exposures have been demonstrated to decrease lung function among firefighters. In this article, the authors demonstrated the feasibility of using small real-time particle sensors to inform wildland firefighters so they may make informed decisions on the use of personal respiratory protection. Using 1 mg/m3 as an indicator point for use of appropriately designed respiratory protection, such sensors could help prevent 16% to 74% of particulate exposure during prescribed burns when firefighters assess exposure as low or medium. Adherence to such a guideline for the use of respiratory protection would involve its deployment during 3% to 22% of individual 8-hour shifts. In addition, data-logging sensors would provide a valuable tool for tracking exposure to particulates among wildland firefighters for occupational health monitoring. PMID:16961007

Edwards, Rufus; Johnson, Michael; Dunn, Kevin H; Naeher, Luke P

2005-01-01

59

Safety of endoscopic retrograde cholangiopancreatography in pregnancy: Fluoroscopy time and fetal exposure, does it matter?  

PubMed Central

AIM: To estimate the fetal radiation exposure using thermoluminescent dosimeters (TLD’s) in pregnant patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) and assess its relevance. METHODS: Data on thirty-five therapeutic ERCPs conducted in pregnant patients from 2001 to 2009 were retrieved from a prospective database. Techniques to minimize fluoroscopy time were implemented and the fluoroscopy times captured. TLD’s were placed on the mother to estimate the fetal radiation exposure and the results were compared to the maximum allowed dose of radiation to the fetus [0.005 gray (Gy)]. Obstetrics consultations were obtained and the fetus was monitored before and after the ERCP. Fluoroscopy was performed at 75 kVp. ERCP was performed with the patients supine by dedicated biliary endoscopists performing more than 500 cases a year. RESULTS: A total of 35 pregnant patients underwent ERCP and biliary sphincterotomy (14 in first trimester, 11 in second trimester, and 10 in third trimester). Mean maternal age was 25 years (range 16-37 years) and mean gestational age was 18.9 wk (range 4-35 wk). Mean fluoroscopy time was 0.15 min (range 0-1 min). For 23 women, the estimated fetal radiation exposure was almost negligible (< 0.0001 Gy) while for 8 women, it was within the 0.0001-0.0002 Gy range. Three women had an estimated fetal radiation exposure between 0.0002 and 0.0005 Gy and 1 woman had an estimated fetal radiation exposure greater than 0.0005 Gy. Complications included 2 post-sphincterotomy bleeds, 2 post-ERCP pancreatitis, and 1 fatal acute respiratory distress syndrome. One patient developed cholecystitis 2 d after ERCP. CONCLUSION: ERCP with modified techniques is safe during pregnancy, and estimating the fetal radiation exposure from the fluoroscopy time or measuring it via TLD’s is unnecessary.

Smith, Ioana; Gaidhane, Monica; Goode, Allen; Kahaleh, Michel

2013-01-01

60

INFLUENCE OF TIME OF EXPOSURE TO CARBON TETRACHLORIDE ON TOXIC LIVER INJURY  

EPA Science Inventory

The study was conducted to determine whether, and by what mechanisms, time of exposure could influence the ability of a model hepatotoxin, carbon tetrachloride (CCl4) to cause liver injury. Rats dosed orally with CCl4 during their active/dark cycle were found to be more susceptib...

61

Effect of detector exposure time on the apparent diffusion coefficient measured by single particle tracking  

Microsoft Academic Search

We present results from simulation of Brownian motion of nanoparticles where we also take into account the averaging imposed by the exposure period E of the detector. The diffusion coefficient is estimated from the measured displacements of the particles over a prescribed delay time deltat. Results from free diffusion simulations show a clear dependency of the estimated diffusion coefficient on

Shahram Pouya; Manoochehr Koochesfahani; Richard di Liu

2008-01-01

62

The molecular basis of simple relationships between exposure concentration and toxic effects with time.  

PubMed

Understanding the toxicity of chemicals to organisms requires considering the molecular mechanisms involved as well as the relationships between exposure concentration and toxic effects with time. Our current knowledge about such relationships is mainly explained from a toxicodynamic and toxicokinetic perspective. This paper re-introduces an old approach that takes into account the biochemical mode of action and their resulting biological effects over time of exposure. Empirical evidence demonstrates that the Druckrey-Küpfmüller toxicity model, which was validated for chemical carcinogens in the early 1960s, is also applicable to a wide range of toxic compounds in ecotoxicology. According to this model, the character of a poison is primarily determined by the reversibility of critical receptor binding. Chemicals showing irreversible or slowly reversible binding to specific receptors will produce cumulative effects with time of exposure, and whenever the effects are also irreversible (e.g. death) they are reinforced over time; these chemicals have time-cumulative toxicity. Compounds having non-specific receptor binding, or involving slowly reversible binding to some receptors that do not contribute to toxicity, may also be time-dependent; however, their effects depend primarily on the exposure concentration, with time playing a minor role. Consequently, the mechanism of toxic action has important implications for risk assessment. Traditional risk approaches cannot predict the impacts of toxicants with time-cumulative toxicity in the environment. New assessment procedures are needed to evaluate the risk that the latter chemicals pose on humans and the environment. An example is shown to explain how the risk of time-dependent toxicants is underestimated when using current risk assessment protocols. PMID:23603429

Tennekes, Henk A; Sánchez-Bayo, Francisco

2013-07-01

63

Personal exposure to ultrafine particles: the influence of time-activity patterns.  

PubMed

Exposure to ultrafine particles (UFPs) is deemed to be a major risk affecting human health. Therefore, airborne particle studies were performed in the recent years to evaluate the most critical micro-environments, as well as identifying the main UFP sources. Nonetheless, in order to properly evaluate the UFP exposure, personal monitoring is required as the only way to relate particle exposure levels to the activities performed and micro-environments visited. To this purpose, in the present work, the results of experimental analysis aimed at showing the effect of the time-activity patterns on UFP personal exposure are reported. In particular, 24 non-smoking couples (12 during winter and summer time, respectively), comprised of a man who worked full-time and a woman who was a homemaker, were analyzed using personal particle counter and GPS monitors. Each couple was investigated for a 48-h period, during which they also filled out a diary reporting the daily activities performed. Time activity patterns, particle number concentration exposure and the related dose received by the participants, in terms of particle alveolar-deposited surface area, were measured. The average exposure to particle number concentration was higher for women during both summer and winter (Summer: women 1.8 × 10(4) part. cm(-3); men 9.2 × 10(3) part. cm(-3); Winter: women 2.9 × 10(4) part. cm(-3); men 1.3 × 10(4) part. cm(-3)), which was likely due to the time spent undertaking cooking activities. Staying indoors after cooking also led to higher alveolar-deposited surface area dose for both women and men during the winter time (9.12 × 10(2) and 6.33 × 10(2) mm(2), respectively), when indoor ventilation was greatly reduced. The effect of cooking activities was also detected in terms of women's dose intensity (dose per unit time), being 8.6 and 6.6 in winter and summer, respectively. On the contrary, the highest dose intensity activity for men was time spent using transportation (2.8 in both winter and summer). PMID:24080417

Buonanno, G; Stabile, L; Morawska, L

2014-01-15

64

Time course of bronchial cell inflammation following exposure to diesel particulate matter using a modified EAVES.  

PubMed

Electrostatic deposition of particles onto the surface of well-differentiated airway cells is a rapid and efficient means to screen for toxicity associated with exposure to fine and ultrafine particulate air pollution. This work describes the development and application of an electrostatic aerosol in vitro exposure system (EAVES) with increased throughput and ease-of-use. The modified EAVES accommodates standard tissue culture plates and uses an alternating electric field to deposit a net neutral charge of aerosol onto air-interface cell cultures. Using this higher-throughput design, we were able to examine the time-course (1, 3, 6, 9, and 24h post-exposure) of transcript production and cytotoxicity in well-differentiated human bronchial cells exposed to diesel particulate matter at levels of 'real-world' significance. Statistically significant responses were observed at exposure levels (?0.4?g/cm(2)) much lower than typically reported in vitro using traditional submerged/resuspended techniques. Levels of HO-1, IL-8, CYP1A1, COX-2, and HSP-70 transcripts increased immediately following diesel particulate exposure and persisted for several hours; cytotoxicity was increased at 24h. The modified EAVES provides a platform for higher throughput, more efficient and representative testing of aerosol toxicity in vitro. PMID:24681185

Hawley, Brie; McKenna, Dave; Marchese, Anthony; Volckens, John

2014-08-01

65

Phase-shifting human circadian rhythms: influence of sleep timing, social contact and light exposure  

NASA Technical Reports Server (NTRS)

1. Both the timing of behavioural events (activity, sleep and social interactions) and the environmental light-dark cycle have been reported to contribute to entrainment of human circadian rhythms to the 24 h day. Yet, the relative contribution of those putative behavioural synchronizers to that of light exposure remains unclear. 2. To investigate this, we inverted the schedule of rest, sedentary activity and social contact of thirty-two young men either with or without exposure to bright light. 3. On this inverted schedule, the endogenous component of the core temperature rhythm of subjects who were exposed to bright light showed a significant phase shift, demonstrating that they were adapting to the new schedule. In contrast, the core temperature rhythm of subjects who were not exposed to bright light moved on average 0.2 h later per day and after 10 days had not significantly adapted to the new schedule. 4. The direction of phase shift in the groups exposed to bright light was dependent on the time of bright light exposure, while control subjects drifted to a later hour regardless of the timing of their schedule of sleep timing, social contact and meals. 5. These results support the concept that the light-dark cycle is the most important synchronizer of the human circadian system. They suggest that inversion of the sleep-wake, rest-activity and social contact cycles provides relatively minimal drive for resetting the human circadian pacemaker. 6. These data indicate that interventions designed to phase shift human circadian rhythms for adjustment to time zone changes or altered work schedules should focus on properly timed light exposure.

Duffy, J. F.; Kronauer, R. E.; Czeisler, C. A.

1996-01-01

66

[Effectiveness of instrument disinfectants under increased protein exposure and for standing times up to two weeks].  

PubMed

To examine the possibility of prolongation of the standing times of instrument disinfectants, in vitro tests under high albumin exposure and tests in clinical practice were done. Concerning in vitro tests: The bactericidal effectiveness of 7 commercial preparations for instrument disinfection with different basic substances was determined in quantitative suspension tests and of 8 preparations in practice-oriented tests according to the guidelines for testing and approval of instrument disinfectants by the DGHM (German Society for Hygiene and Microbiology). Tests were carried out under increased albumin exposure and at prolonged standing times up to 12 days. The instrument disinfectants showed microbicidal efficacy up to 12 days at working concentrations slightly increased in relation to the concentrations listed by the DGHM. Concerning tests in clinical practice: In 4 clinical wards (intensive care unit, cystoscopy unit, urological operation unit, gastroenterological endoscopy unit with ERPC) the preparations for instrument disinfection were tested up to 12 days in respect to the protein exposure and the disinfecting activity of the working solution. The working solution was not renewed during the 12 days. The inserted instruments were recorded. Concentration of the disinfectants and the protein concentration were daily determined. Disinfecting activity was examined by practice-oriented microbiological tests. The highest protein exposure was 0.098% after a standing time of 12 days. A loss in concentration of disinfectants could not be found. Nevertheless independent from the protein exposure there was a loss in disinfecting activity of the tap water diluted specimens from the clinical practice. Loss in activity could not be seen in the specimen from laboratory parallel tests, which were diluted by water of standard hardness. The loss in disinfecting activity of the tap water diluted preparation from the gastroenterological endoscopy unit versus a dilution by water of standard hardness could be confirmed in control experiments (practice-oriented tests with S. aureus over a period of 5 days). PMID:1388617

Rehork, B; Azzaui, S; Naumann, C; Rüden, H

1992-08-01

67

Exposure measurement error in time-series studies of air pollution: concepts and consequences.  

PubMed Central

Misclassification of exposure is a well-recognized inherent limitation of epidemiologic studies of disease and the environment. For many agents of interest, exposures take place over time and in multiple locations; accurately estimating the relevant exposures for an individual participant in epidemiologic studies is often daunting, particularly within the limits set by feasibility, participant burden, and cost. Researchers have taken steps to deal with the consequences of measurement error by limiting the degree of error through a study's design, estimating the degree of error using a nested validation study, and by adjusting for measurement error in statistical analyses. In this paper, we address measurement error in observational studies of air pollution and health. Because measurement error may have substantial implications for interpreting epidemiologic studies on air pollution, particularly the time-series analyses, we developed a systematic conceptual formulation of the problem of measurement error in epidemiologic studies of air pollution and then considered the consequences within this formulation. When possible, we used available relevant data to make simple estimates of measurement error effects. This paper provides an overview of measurement errors in linear regression, distinguishing two extremes of a continuum-Berkson from classical type errors, and the univariate from the multivariate predictor case. We then propose one conceptual framework for the evaluation of measurement errors in the log-linear regression used for time-series studies of particulate air pollution and mortality and identify three main components of error. We present new simple analyses of data on exposures of particulate matter < 10 microm in aerodynamic diameter from the Particle Total Exposure Assessment Methodology Study. Finally, we summarize open questions regarding measurement error and suggest the kind of additional data necessary to address them. Images Figure 1 Figure 2 Figure 3

Zeger, S L; Thomas, D; Dominici, F; Samet, J M; Schwartz, J; Dockery, D; Cohen, A

2000-01-01

68

Time-diary research and human exposure assessment: Some methodological considerations  

NASA Astrophysics Data System (ADS)

The unique features of and approaches to collecting time-diary data in the survey context are discussed. Sample diary report forms and activity coding schemes are presented and discussed, along with data from two national time-diary studies. These illustrate the range of useful data available from time diaries, as well as providing normative data regarding the amount of time that the American public spends in various activities. Location from diaries could be generalized to provide overall times spent in environments that vary in pollution levels. Various problems arise in matching these national time-use data with time estimate data from human exposure studies. The multiple respondent demands in these studies mean that daily activity patterns may be atypical and that respondents may also not report their activities as accurately or as completely as in a study founded solely on time. Some ways of reconciling these differences are proposed along with some suggestions for needed methodological research to increase the generalizability of pollution exposure estimates.

Robinson, John P.

69

Measurement of fluid properties using rapid-double-exposure and time-average holographic interferometry  

SciTech Connect

The holographic recording of the time history of a flow feature in three dimensions is discussed. The use of diffuse illumination holographic interferometry or the three dimensional visualization of flow features such as shock waves and turbulent eddies is described. The double-exposure and time-average methods are compared using the characteristic function and the results from a flow simulator. A time history requires a large hologram recording rate. Results of holographic cinematography of the shock waves in a flutter cascade are presented as an example. Future directions of this effort, including the availability and development of suitable lasers, are discussed.

Decker, A.J.

1984-06-01

70

Measurement of fluid properties using rapid-double-exposure and time-average holographic interferometry  

NASA Technical Reports Server (NTRS)

The holographic recording of the time history of a flow feature in three dimensions is discussed. The use of diffuse illumination holographic interferometry or the three dimensional visualization of flow features such as shock waves and turbulent eddies is described. The double-exposure and time-average methods are compared using the characteristic function and the results from a flow simulator. A time history requires a large hologram recording rate. Results of holographic cinematography of the shock waves in a flutter cascade are presented as an example. Future directions of this effort, including the availability and development of suitable lasers, are discussed.

Decker, A. J.

1984-01-01

71

Thermal performance curves, phenotypic plasticity, and the time scales of temperature exposure.  

PubMed

Thermal performance curves (TPCs) describe the effects of temperature on biological rate processes. Here, we use examples from our work on common killifish (Fundulus heteroclitus) to illustrate some important conceptual issues relating to TPCs in the context of using these curves to predict the responses of organisms to climate change. Phenotypic plasticity has the capacity to alter the shape and position of the TPCs for acute exposures, but these changes can be obscured when rate processes are measured only following chronic exposures. For example, the acute TPC for mitochondrial respiration in killifish is exponential in shape, but this shape changes with acclimation. If respiration rate is measured only at the acclimation temperature, the TPC is linear, concealing the underlying mechanistic complexity at an acute time scale. These issues are particularly problematic when attempting to use TPCs to predict the responses of organisms to temperature change in natural environments. Many TPCs are generated using laboratory exposures to constant temperatures, but temperature fluctuates in the natural environment, and the mechanisms influencing performance at acute and chronic time scales, and the responses of the performance traits at these time scales may be quite different. Unfortunately, our current understanding of the mechanisms underlying the responses of organisms to temperature change is incomplete, particularly with respect to integrating from processes occurring at the level of single proteins up to whole-organism functions across different time scales, which is a challenge for the development of strongly grounded mechanistic models of responses to global climate change. PMID:21841184

Schulte, Patricia M; Healy, Timothy M; Fangue, Nann A

2011-11-01

72

Investigating the American Time Use Survey from an exposure modeling perspective.  

PubMed

This paper describes an evaluation of the US Bureau of Labor Statistics' American Time Use Survey (ATUS) for potential use in modeling human exposures to environmental pollutants. The ATUS is a large, on-going, cross-sectional survey of where Americans spend time and what activities they undertake in those locations. The data are reported as a series of sequential activities over a 24-h time period--a "diary day"--starting at 0400 hours. Between 12,000 and 13,000 surveys are obtained each year and the Bureau has plans to continue ATUS for the foreseeable future. The ATUS already has about 73,000 diary days of data, more than twice as many as that which currently exists in the US Environmental Protection Agency's (EPA) "Consolidated Human Activity Database" (CHAD) that the Agency uses for exposure modeling purposes. There are limitations for using ATUS in modeling human exposures to environmental pollutants. The ATUS does not report the location for a number of activities regarded as "personal." For 2006, personal activities with missing location information totaled 572?min/day, on average, for survey participants: about 40% of their day. Another limitation is that ATUS does not distinguish between indoor and outdoor activities at home, two of the traditional locational demarcations used in human exposure modeling. This lack of information affects exposure estimates to both indoor and outdoor air pollutants and potentially affects non-dietary ingestion estimates for children, which can vary widely depending on whether or not a child is indoors. Finally, a detailed analysis of the work travel activity in a subsample from ATUS 2006 indicates that the coding scheme is not fully consistent with a CHAD-based exposure modeling approach. For ATUS respondents in this subsample who reported work as an activity, roughly 48% of their days were missing work travel at one or both ends of the work shift or reported within work-shift travel inconsistently. An extensive effort would be needed to recode work travel data from ATUS for EPA's exposure modeling purposes. PMID:20040930

George, Barbara Jane; McCurdy, Thomas

2011-01-01

73

Breast cancer risk after occupational solvent exposure: the influence of timing and setting.  

PubMed

Organic solvents are ubiquitous in occupational settings where they may contribute to risks for carcinogenesis. However, there is limited information on organic solvents as human breast carcinogens. We examined the relationship between occupational exposure to solvents and breast cancer in a prospective study of 47,661 women with an occupational history in the Sister Study cohort. Occupational solvent exposure was categorized using self-reported job-specific solvent use collected at baseline. Multivariable Cox regression analyses were used to assess breast cancer risk, adjusting for established breast cancer risk factors. A total of 1,798 women were diagnosed with breast cancer during follow-up, including 1,255 invasive cases. Overall the risk of invasive breast cancer was not associated with lifetime exposure to solvents [HR, 1.04; 95% confidence interval (CI), 0.88-1.24]. Parous women who worked with solvents before their first full-term birth had an increased risk of estrogen receptor-positive invasive breast cancer compared with women who never worked with solvents (HR, 1.39; 95% CI, 1.03-1.86). A significantly elevated risk for estrogen receptor-positive invasive breast cancer was associated with solvent exposure among clinical laboratory technologists and technicians (HR, 2.00; 95% CI, 1.07-3.73). Occupational exposure to solvents before first birth, a critical period of breast tissue differentiation, may result in increased vulnerability for breast cancer. Our findings suggest a need for future studies in this area to focus on exposure time windows and solvent types in different occupational settings. Cancer Res; 74(11); 3076-83. ©2014 AACR. PMID:24879566

Ekenga, Christine C; Parks, Christine G; D'Aloisio, Aimee A; DeRoo, Lisa A; Sandler, Dale P

2014-06-01

74

Polychlorinated biphenyl (PCB) exposure in mothers and time to pregnancy in daughters  

PubMed Central

Developmental exposure to polychlorinated biphenyls (PCBs) disrupts reproduction in animals. Human data are lacking. We measured PCBs in preserved mothers' serum samples collected during 1960-1963, 1-3 days after their daughters' birth. We recorded time to pregnancy (TTP) in 289 daughters 28-31 years later. PCB congeners 187, 156, and 99 in mother's serum were associated with longer TTP in their daughters while PCB congeners 105,138 and 183 were associated shorter TTP. Probability of pregnancy fell by 38% (95% CI 17%-53%) and infertility was higher (30% not pregnant after 13 cycles vs.11% not pregnant after 13 cycles) among women whose mothers had a higher proportion of PCB congeners associated with longer TTP (75th percentile versus 25th percentile).This study demonstrates, for the first time, that developmental exposure to PCBs may disrupt pregnancy in humans.

Cohn, Barbara A.; Cirillo, Piera M.; Sholtz, Robert I.; Ferrara, Assiamira; Park, June-Soo; Schwingl, Pamela J.

2011-01-01

75

Timing and Duration of Drug Exposure Affects Outcomes of a Drug-Nutrient Interaction During Ontogeny  

PubMed Central

Significant drug-nutrient interactions are possible when drugs and nutrients share the same absorption and disposition mechanisms. During postnatal development, the outcomes of drug-nutrient interactions may change with postnatal age since these processes undergo ontogenesis through the postnatal period. Our study investigated the dependence of a significant drug-nutrient interaction (cefepime-carnitine) on the timing and duration of drug exposure relative to postnatal age. Rat pups were administered cefepime (5 mg/kg) twice daily subcutaneously according to different dosing schedules (postnatal day 1-4, 1-8, 8-11, 8-20, or 1-20). Cefepime significantly reduced serum and heart L-carnitine levels in postnatal day 1-4, 1-8 and 8-11 groups and caused severe degenerative changes in ventricular myocardium in these groups. Cefepime also altered the ontogeny of several key L-carnitine homeostasis pathways. The qualitative and quantitative changes in levels of hepatic ?-butyrobetaine hydroxylase mRNA and activity, hepatic trimethyllysine hydroxlase mRNA, intestinal organic cation/carnitine transporter (Octn) mRNA, and renal Octn2 mRNA depended on when during postnatal development the cefepime exposure occurred and duration of exposure. Despite lower levels of heart L-carnitine in earlier postnatal groups, levels of carnitine palmitoyltransferase mRNA and activity, heart Octn2 mRNA and ATP levels in all treatment groups remained unchanged with cefepime exposure. However, changes in other high energy phosphate substrates were noted and reductions in the phosphocreatine/ATP ratio were found in rat pups with normal serum L-carnitine levels. In summary, our data suggest a significant drug-nutrient transport interaction in developing neonates, the nature of which depends on the timing and duration of exposure relative to postnatal age.

Ling, Binbing; Aziz, Caroline; Wojnarowicz, Chris; Olkowski, Andrew; Alcorn, Jane

2010-01-01

76

Toxicokinetics of the flame retardant hexabromocyclododecane gamma: effect of dose, timing, route, repeated exposure, and metabolism.  

PubMed

Hexabromocyclododecane-gamma (?-HBCD) is the predominate diastereoisomer in the commercial HBCD mixture used as a flame retardant in a wide variety of consumer products. Three main diastereoisomers, alpha (?), beta (?), and gamma (?), comprise the mixture. Despite the ?-diastereoisomer being the major diastereoisomer in the mixture and environmental samples, the ?-diastereoisomer predominates human tissue and wildlife. This study was conducted to characterize absorption, distribution, metabolism, and excretion parameters of ?-HBCD with respect to dose and time following a single acute exposure and repeated exposure in adult female C57BL/6 mice. Results suggest that 85% of the administered dose (3 mg/kg) was absorbed after po exposure. Disposition was dose independent and did not significantly change after 10 days of exposure. Liver was the major depot (< 0.3% of dose) 4 days after treatment followed by blood, fat, and then brain. ?-HBCD was rapidly metabolized and eliminated in the urine and feces. For the first time, in vivo stereoisomerization was observed of the ?-diastereoisomer to the ?-diastereoisomer in liver and brain tissues and to the ?- and ?-diastereoisomer in fat and feces. Polar metabolites in the blood and urine were a major factor in determining the initial whole-body half-life (1 day) after a single po exposure. Elimination, both whole-body and from individual tissues, was biphasic. Initial half-lives were approximately 1 day, whereas terminal half-lives were up to 4 days, suggesting limited potential for ?-diastereoisomer bioaccumulation. The toxicokinetic behavior reported here has important implications for the extrapolation of toxicological studies of the commercial HBCD mixture to the assessment of risk. PMID:20562218

Szabo, David T; Diliberto, Janet J; Hakk, Heldur; Huwe, Janice K; Birnbaum, Linda S

2010-10-01

77

Peripheral nerve stimulation by induced electric currents: Exposure to time-varying magnetic fields  

Microsoft Academic Search

The review evaluates thresholds of peripheral nerve stimulation by complex current waveforms. A neuroelectric model employing\\u000a Frankenhaeuser-Huxley membrane nonlinearities is used to derive excitation thresholds for monophasic and biphasic pulse sequences,\\u000a as well as sinusoidal stimuli. The model, along with principles of magnetic field induction, is used to derive criteria of\\u000a acceptability for exposure to time-varying magnetic fields. Applications to

J. P. Reilly

1989-01-01

78

Time-averaged exposures to sup 220 Rn and sup 222 Rn progeny in Colorado homes  

Microsoft Academic Search

Week-long time-averaged exposures to naturally occurring ²²°Rn and ²²²Rn progeny have been measured at several locations in Colorado by monitoring the alpha activity collected continuously on a fixed-membrane filter. The alpha-energy spectrum associated with the activity collected on the filter was recorded every 15 min using a microcomputer-controlled alpha spectrometer. The alpha counts observed in three energy regions permitted complete

D. E. Martz; R. J. Falco; G. H. Jr. Langner

1990-01-01

79

Exposure time-dependent cadmium toxicity to Moina macrocopa (Cladocera): a life table demographic study  

Microsoft Academic Search

In this work, we quantified the life table demographic responses of Moina macrocopa daily exposed to three concentrations, 0, 0.08, 0.16, and 0.32 mg l?1 of CdCl2 for 3, 6, 12, and 24 h. These cadmium levels represented 10–50% of the median lethal concentration known for M. macrocopa. In general, increase in CdCl2 concentration and increase in the exposure time had a negative

José Luis Gama-Flores; S. S. S. Sarma; S. Nandini

2007-01-01

80

Real-time method for the measurement of noise exposure from communication headsets  

Microsoft Academic Search

A method for measuring noise exposure from communication headsets is presented. It is based on an accurate acousto-mechanical model of the human head, and a filter to transform the data from the eardrum level to equivalent diffuse free-field values. The filter fits an existing integrating sound-level meter (Bruel and Kjaer type 2231), allowing measurements in real-time. The measurements were validated

Baily Seshagiri

1996-01-01

81

Exposure to chemical cocktails before or after conception - The effect of timing on ovarian development?  

PubMed Central

Exposure of female fetuses to environmental chemicals (ECs) during pregnancy results in a disturbed ovarian adult phenotype. We investigated the influence of pre- and/or post-conception exposure to low-level mixtures of ECs on the structure and function of the fetal ovine ovary. We examined ovarian morphology, expression of oocyte and granulosa cell-specific genes and proteome. Female fetuses were collected at day 110 of gestation, from dams exposed continuously until, and after mating, by grazing in pastures treated with sewage sludge as a fertiliser (TT) or in control fields treated with inorganic fertiliser (CC). In addition, in a cross-over design, fetal ovaries were collected from dams maintained on sludge pastures up to the time of mating but then transferred to control pastures (TC) and, reciprocally, those transferred from control to treated pastures at mating (CT). On examination, the proportion of type 1a follicles (activating primordial follicles) was significantly lower in animals from the CT groups compared with CC and TT groups (P < 0.05). Of the 23 ovarian gene transcripts studied, 14 were altered in the ovaries of exposed fetuses (CT, TC, and TT) relative to controls, with the largest number of changes observed in cross-exposure pattern groups (CT or TC). Continuous EC exposure (TT) produced fewer transcript alterations and only two genes (INHBA and GSN) presented differential profiles between CC and TT. Fetal ovarian proteome analysis (2-DE gels) showed, across all exposure groups, 86 differentially expressed protein spots compared to controls. Animals in the CT group exhibited the highest number (53) while TC and TT presented the same number of affected protein spots (42). Fetal ovarian proteins with altered expression included MVP (major vault protein) and several members of the heat-shock family (HSPA4L, HSP90AA1 and HSF1). The present findings indicate that continuous maternal EC exposure before and during gestation, are less deleterious for fetal ovarian development than a change in maternal EC exposure between pre and post-conception. The pathways by which the ovary responds to this chemical stress were common in TT, CT, TC exposed foetuses. In addition to the period of pregnancy, the pre-conception period appears also as crucial for conditioning long-term effects of EC exposure on ovarian development and primordial follicle reserve and hence future fertility.

Bellingham, Michelle; Amezaga, Maria R.; Mandon-Pepin, Beatrice; Speers, Christopher J.B.; Kyle, Carol E.; Evans, Neil P.; Sharpe, Richard M.; Cotinot, Corinne; Rhind, Stewart M.; Fowler, Paul A.

2013-01-01

82

Microgravity Inhibits Resting T Cell Immunity in an Exposure Time-Dependent Manner  

PubMed Central

Background: Decline immune function is well documented after spaceflights. Microgravity is one of the key factors directly suppressing the function of immune system. Though T cell immune response was inhibited by microgravity, it is not clearly whether activation would be inhibited after a pre-exposure of microgravity on T lymphocytes at the resting state. Methods: We herein investigated the response ability of resting CD4+ and CD8+ T cells experiencing pre-exposure of modeled microgravity (MMg) for 0, 8, 16 and 24 hrs to concanavalin A (ConA) stimulation. The phenotypes and subsets of immune cells were determined by flow cytometry. Results: Both CD4+ and CD8+ T cells with an MMg pre-exposure exhibited decreased expressions of activation-markers including CD25, CD69 and CD71, inflammatory cytokine secretion and cell proliferation in response to ConA compared with T cells with 1g controls in an MMg exposure time- dependent manner. Moreover, short term MMg treatment caused more severe decreased proliferation in CD4+ T cells than in CD8+ T cells. Conclusions: MMg can directly impact on resting T cell subsets. CD4+ T cells were more sensitive to the microgravity inhibition than CD8+ T cells in respect of cell proliferation. These results offered new insights for the MMg-caused T cell functional defects.

Luo, Haiying; Wang, Chongzhen; Feng, Meifu; Zhao, Yong

2014-01-01

83

Heavy metal toxicity to Lemna minor: studies on the time dependence of growth inhibition and the recovery after exposure  

Microsoft Academic Search

Environmental concentrations of toxic substances are not necessarily constant but fluctuate over time. Periods of intense exposure might be followed by episodes with a relatively low or no exposure, in principle allowing exposed organisms to recover from toxic injury. The growth reproduction assay with the limnic vascular plant Lemna minor allows for convenient studies on the time dependence of the

Wiebke Drost; Marianne Matzke; Thomas Backhaus

2007-01-01

84

Effect modification of the association of cumulative exposure and cancer risk by intensity of exposure and time since exposure cessation: a flexible method applied to cigarette smoking and lung cancer in the SYNERGY Study.  

PubMed

The indiscriminate use of the cumulative exposure metric (the product of intensity and duration of exposure) might bias reported associations between exposure to hazardous agents and cancer risk. To assess the independent effects of duration and intensity of exposure on cancer risk, we explored effect modification of the association of cumulative exposure and cancer risk by intensity of exposure. We applied a flexible excess odds ratio model that is linear in cumulative exposure but potentially nonlinear in intensity of exposure to 15 case-control studies of cigarette smoking and lung cancer (1985-2009). Our model accommodated modification of the excess odds ratio per pack-year of cigarette smoking by time since smoking cessation among former smokers. We observed negative effect modification of the association of pack-years of cigarette smoking and lung cancer by intensity of cigarette smoke for persons who smoked more than 20-30 cigarettes per day. Patterns of effect modification were similar across individual studies and across major lung cancer subtypes. We observed strong negative effect modification by time since smoking cessation. Application of our method in this example of cigarette smoking and lung cancer demonstrated that reducing a complex exposure history to a metric such as cumulative exposure is too restrictive. PMID:24355332

Vlaanderen, Jelle; Portengen, Lützen; Schüz, Joachim; Olsson, Ann; Pesch, Beate; Kendzia, Benjamin; Stücker, Isabelle; Guida, Florence; Brüske, Irene; Wichmann, Heinz-Erich; Consonni, Dario; Landi, Maria Teresa; Caporaso, Neil; Siemiatycki, Jack; Merletti, Franco; Mirabelli, Dario; Richiardi, Lorenzo; Gustavsson, Per; Plato, Nils; Jöckel, Karl-Heinz; Ahrens, Wolfgang; Pohlabeln, Hermann; Tardón, Adonina; Zaridze, David; Field, John K; 't Mannetje, Andrea; Pearce, Neil; McLaughlin, John; Demers, Paul; Szeszenia-Dabrowska, Neonila; Lissowska, Jolanta; Rudnai, Peter; Fabianova, Eleonora; Stanescu Dumitru, Rodica; Bencko, Vladimir; Foretova, Lenka; Janout, Vladimir; Boffetta, Paolo; Forastiere, Francesco; Bueno-de-Mesquita, Bas; Peters, Susan; Brüning, Thomas; Kromhout, Hans; Straif, Kurt; Vermeulen, Roel

2014-02-01

85

Individual lifetime exposure to inorganic arsenic using a space–time information system  

Microsoft Academic Search

Objectives  A space–time information system (STIS) based method is introduced for calculating individual-level estimates of inorganic\\u000a arsenic exposure over the adult life-course. STIS enables visualization and analysis of space–time data, overcoming some of\\u000a the constraints inherent to spatial-only Geographic Information System software. The power of this new methodology is demonstrated\\u000a using data from southeastern Michigan where 8% of the population is

Jaymie R. Meliker; Melissa J. Slotnick; Gillian A. AvRuskin; Andrew Kaufmann; Stacey A. Fedewa; Pierre Goovaerts; Geoffrey J. Jacquez; Jerome O. Nriagu

2007-01-01

86

Variation in voxel value distribution and effect of time between exposures in six CBCT units.  

PubMed

The aim of this study is to assess the variation in voxel value distribution in volumetric data sets obtained by six cone beam CT (CBCT) units, and the effect of time between exposures. Six CBCT units [Cranex(®) 3D (CRAN; Soredex Oy, Tuusula, Finland), Scanora(®) 3D (SCAN; Soredex Oy), NewTom™ 5G (NEWT; QR Srl, Verona, Italy), Promax(®) Dimax 3 (Planmeca Oy, Helsinki, Finland), i-CAT (Imaging Sciences International, Hatfield, PA) and 3D Accuitomo FPD80 (Morita, Kyoto, Japan)] were tested. Two volumetric data sets of a dry human skull embedded in acrylic were acquired by each CBCT unit in two sessions on separate days. Each session consisted of 20 exposures: 10 acquired with 30?min between exposures and 10 acquired immediately one after the other. CBCT data were exported as digital imaging and communications in medicine (DICOM) files and converted to text files. The text files were re-organized to contain x-, y- and z-position and grey shade for each voxel. The files were merged to contain 1 record per voxel position, including the voxel values from the 20 exposures in a session. For each voxel, subtractions were performed between Data Set 1 and the remaining 19 data sets (1?-?2, 1?-?3, etc) in a session. Means, medians, ranges and standard deviations for grey shade variation in the subtraction data sets were calculated for each unit and session. For all CBCT units, variation in voxel values was observed throughout the 20 exposures. A "fingerprint" for the grey shade variation was observed for CRAN, SCAN and NEWT. For the other units, the variation was (apparently) randomly distributed. Large discrepancies in voxel value distribution are seen in CBCT images. This variation should be considered in studies that assess minute changes in CBCT images. PMID:24678846

Spin-Neto, R; Gotfredsen, E; Wenzel, A

2014-01-01

87

Toxicokinetics of the flame retardant hexabromocyclododecane alpha: effect of dose, timing, route, repeated exposure, and metabolism.  

PubMed

Alpha-hexabromocyclododecane (?-HBCD) is an emerging persistent organic pollutant present in the hexabromocyclododecane (HBCD) commercial mixture. HBCD is used as an additive flame retardant in a wide variety of household consumer products. Three main stereoisomers, alpha (?), beta (?), and gamma (?), comprise roughly 10, 10, and 80% of the mixture, respectively. Despite its small contribution to HBCD global production and usage, ?-HBCD is the major stereoisomer found in wildlife and human tissues including breast milk and blood in North America, European Union, and Asia. No mammalian or human data are currently available regarding the toxicokinetics of ?-HBCD. This study was conducted in an effort to fully characterize the absorption, distribution, metabolism, and elimination of ?-HBCD following a single and repeated exposure with respect to dose, time, and route of administration in female C57BL/6 mice. Results indicate that ?90% of the administered dose (3 mg/kg) was absorbed after oral exposure. Disposition was (1) dictated by lipophilicity, as adipose, liver, muscle, and skin were major depots and (2) was dose dependent with nonlinear accumulation at higher doses. Elimination, both whole-body and from individual tissues, was biphasic. ?-HBCD-derived radioactivity was excreted in the feces as parent and metabolites, whereas urine only contained metabolites. Presence of polar metabolites in the blood and urine were a major factor in determining the rapid initial whole-body half-life after a single oral exposure. Initial half-lives were ?1-3 days and much longer terminal half-lives of 17 days were observed, suggesting the potential for ?-HBCD bioaccumulation. A 10-day repeated study supports ?-HBCD bioaccumulation potential. Stereoisomerization previously observed after exposure to ?-HBCD was not seen after exposure of ?-HBCD. The toxicokinetic behavior reported here has important implications for the extrapolation of toxicological studies of the commercial HBCD mixture to the assessment of risk of ?-HBCD which is the major stereoisomer found in wildlife and people. PMID:21441408

Szabo, David Taylor; Diliberto, Janet J; Hakk, Heldur; Huwe, Janice K; Birnbaum, Linda S

2011-06-01

88

Using tensor product splines in modeling exposure-time-response relationships: application to the Colorado Plateau Uranium Miners cohort.  

PubMed

An adequate depiction of exposure-time-response relationships is important in assessing public health implications of an occupational or environmental exposure. Recent advances have focused on flexible modeling of the overall shape of latency. Methods are needed to allow for varying shapes of latency under different exposure profiles. A tensor product spline model is proposed for describing exposure-response relationships for protracted time-dependent occupational exposure histories in epidemiologic studies. The methods use flexible multi-dimensional techniques to jointly model age, latency and exposure-response effects. In analyzing data from the Colorado Plateau Uranium Miners cohort, a model that allows for varying exposure-dependent latency shapes is found to be superior to models that only allowed for an overall latency curve. Specifically, the model suggests that, at low exposure levels risk increased at short latencies followed by a slow decline for longer latency periods. On the other hand, risk was higher but did not change much by latency for higher exposure levels. The proposed methodology has the advantage of allowing for latency functions that vary by exposure levels and, conversely, exposure-response relationships that are influenced by the latency structure. PMID:18613262

Berhane, Kiros; Hauptmann, Michael; Langholz, Bryan

2008-11-20

89

Effect of microwave heating with different exposure times on physical and chemical parameters of olive oil.  

PubMed

This study reflects the effect of different microwave heating times (1, 3, 5, 10 and 15 min) on physical and chemical characteristics of three Portuguese olive oils from three protected designation of origin (PDO), "Azeite de Trás-os-Montes PDO", "Azeites da Beira Interior PDO", and "Azeite de Moura PDO". The parameters evaluated were free acidity, peroxide value, specific extinction coefficients (K232 and K270), color and chlorophylls and carotenoids content. A differential pulse voltammeter was also used to monitor the changes in alpha-tocopherol content. The results showed that microwave heating produce losses in the quality of the different analysed olive oils. The heating time did not promote the occurrence of hydrolysis in the samples since no changes in free acidity values were found. All other parameters were affected by exposure time in a similar way: in the first 3 min no marked changes were observed, after that the quality of the oil decrease significantly. The microwave heating time also affects the total chlorophylls, carotenoids and alpha-tocopherol contents which clearly decreased as long as the exposure time increases. After 15 min of heating the electrochemical signal, due to the alpha-tocopherol, disappear completely in the voltamogram. PMID:18996164

Malheiro, Ricardo; Oliveira, Ivo; Vilas-Boas, Miguel; Falcão, Soraia; Bento, Albino; Pereira, José Alberto

2009-01-01

90

Critical role of sorafenib exposure over time for its antitumor activity in thyroid cancer.  

PubMed

Sorafenib, a multi-kinase inhibitor that targets the VEGF, PDGF and BRAF pathways, has demonstrated significant clinical activity in metastatic differentiated thyroid cancer. However, all patients eventually experience disease progression with a median progression-free survival close to 10 months. Since sorafenib exposure is known to decrease over time, we hypothesized that dose adjustments aiming to restore adequate exposure could lead to further clinical activity. We report, as a proof of concept on a patient with radio-iodine resistant metastatic thyroid cancer, who experienced disease progression after an initial response to sorafenib (400 mg twice daily). Whereas the thyroglobulin-progression-free survival at standard doses was 6 months, iterative dose optimization led to a prolonged progression-free survival up to 41 months. Sorafenib doses were increased up to 1600 mg bid, in order to maintain clinical activity, and to restore active plasma concentration, since sorafenib exposure had decreased over the time. Toxicity was mild and manageable for more than 2 years. However, the patient eventually experienced grade 3 proteinuria leading to treatment discontinuation. This observation opens up new horizons for daily management of radioactive iodine-refractory differentiated thyroid cancer patients progressing under standard doses of sorafenib, and stress the need to monitor its plasma concentration. PMID:24399106

Bellesoeur, Audrey; Carton, Edith; Mir, Olivier; Groussin, Lionel; Blanchet, Benoit; Billemont, Bertrand; Clerc, Jérôme; Goldwasser, François

2014-06-01

91

Real-Time Aircraft Cosmic Ray Radiation Exposure Predictions from the NAIRAS Model  

NASA Astrophysics Data System (ADS)

The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a prototype operational model for predicting commercial aircraft radiation exposure from galactic and solar cosmic rays. NAIRAS predictions are currently streaming live from the project's public website, and the exposure rate nowcast is also available on the SpaceWx smartphone app for iPhone, IPad, and Android. Cosmic rays are the primary source of human exposure to high linear energy transfer radiation at aircraft altitudes, which increases the risk of cancer and other adverse health effects. Thus, the NAIRAS model addresses an important national need with broad societal, public health and economic benefits. There is also interest in extending NAIRAS to the LEO environment to address radiation hazard issues for the emerging commercial spaceflight industry. The processes responsible for the variability in the solar wind, interplanetary magnetic field, solar energetic particle spectrum, and the dynamical response of the magnetosphere to these space environment inputs, strongly influence the composition and energy distribution of the atmospheric ionizing radiation field. Real-time observations are required at a variety of locations within the geospace environment. The NAIRAS model is driven by real-time input data from ground-, atmospheric-, and space-based platforms. During the development of the NAIRAS model, new science questions and observational data gaps were identified that must be addressed in order to obtain a more reliable and robust operational model of atmospheric radiation exposure. The focus of this talk is to present the current capabilities of the NAIRAS model, discuss future developments in aviation radiation modeling and instrumentation, and propose strategies and methodologies of bridging known gaps in current modeling and observational capabilities.

Mertens, C. J.; Tobiska, W.; Kress, B. T.; Xu, X.

2012-12-01

92

Wearable real-time direct reading naphthalene and VOC personal exposure monitor  

NASA Astrophysics Data System (ADS)

Naphthalene has been identified by the National Research Council as a serious health hazard for personnel working with jet fuels and oil-based sealants containing naphthalene. We are developing a family of miniature, self-contained, direct reading personal exposure monitors (PEMs) to detect, differentiate, quantify, and log naphthalene and other volatile organic compounds (VOCs) in the breathing zone of the wearer or in the hands of an industrial hygienist with limits of detection in the low parts per billion (ppb) range. The VOC Dosimeter (VOCDos) described here is a PEM that provides real-time detection and data logging of exposure as well as accumulated dose, with alarms addressing long term and immediate exposure limits. We will describe the sensor, which employs optical methods with a unique excitation source and rapidly refreshable vapor concentrator. This paper addresses the rapidly increasing awareness of the health risks of inhaling jet fuel vapors by Department of Defense (DOD) personnel engaged in or around jet fueling operations. Naphthalene is a one to three percent component of the 5 billion gallons of jet fuels used annually by DOD. Naphthalene is also a component of many other petroleum products such as asphalt and other oil-based sealants. The DOD is the single largest user of petroleum fuels in the United States (20% of all petroleum fuel used). The VOCDos wearable sensor provides real-time detection and data logging of exposure as well as accumulated dose. We will describe the sensor, which employs endogenous fluorescence from VOCs accumulated on a unique, rapidly refreshable, patent-pending concentrator, excited by a unique deep ultraviolet excitation source.

Hug, W. F.; Bhartia, R.; Reid, R. D.; Reid, M. R.; Oswal, P.; Lane, A. L.; Sijapati, K.; Sullivan, K.; Hulla, J. E.; Snawder, J.; Proctor, S. P.

2012-05-01

93

Acute exposure to 2G phase shifts the rat circadian timing system  

NASA Technical Reports Server (NTRS)

The circadian timing system (CTS) provides internal and external temporal coordination of an animal's physiology and behavior. In mammals, the generation and coordination of these circadian rhythms is controlled by a neural pacemaker, the suprachiasmatic nucleus (SCN), located within the hypothalamus. The pacemaker is synchronized to the 24 hour day by time cures (zeitgebers) such as the light/dark cycle. When an animal is exposed to an environment without time cues, the circadian rhythms maintain internal temporal coordination, but exhibit a 'free-running' condition in which the period length is determined by the internal pacemaker. Maintenance of internal and external temporal coordination are critical for normal physiological and psychological function in human and non-human primates. Exposure to altered gravitational environments has been shown to affect the amplitude, mean, and timing of circadian rhythms in species ranging from unicellular organisms to man. However, it has not been determined whether altered gravitational fields have a direct effect on the neural pacemaker, or affect peripheral parameters. In previous studies, the ability of a stimulus to phase shift circadian rhythms was used to determine whether a stimulus has a direct effect on the neural pacemaker. The present experiment was performed in order to determine whether acute exposure to a hyperdynamic field could phase shift circadian rhythms.

Hoban-Higgins, T. M.; Murakami, D. M.; Tandon, T.; Fuller, C. A.

1995-01-01

94

Exposure to high altitude alters tear film osmolarity and breakup time.  

PubMed

Abstract Willmann, Gabriel, Andreas Schatz, M. Dominik Fischer, Kai Schommer, Eberhart Zrenner, Karl U. Bartz-Schmidt, Florian Gekeler, and Katrin Gekeler. Exposure to high altitude alters tear film osmolarity and breakup time. High Alt Med Biol. 15:203-207, 2014.-Aims: High altitude provides environmental conditions with dry air and cold temperatures that may facilitate the development of dry eye symptoms. This study investigated, for the first time, the quality of the tear film during high altitude exposure in healthy subjects. This study is related to the Tübingen High Altitude Ophthalmology (THAO) study. Methods: Tear film osmolarity (TFO), tear film breakup time (TBUT), and Schirmer I and II were used to assess tear film properties under standardized conditions in 14 healthy subjects on day 1, 2, and 4 during exposure to high altitude at the Capanna Margherita (CM; 4559?m, Italy) compared to baseline measurements in Tübingen (341?m, Germany) before (BL1) and after (BL2) exposure. Results: Upon arrival at CM, a significant increase in intra-individual TFO (309.1±19.3, 332.2±24.1, 335.5±28.7, 329.7±19.0, and 308.5±15.3?mOsms/L at BL1, day1, 2, 4,, and BL2, respectively) and a significant decrease of TBUT (11.2±5.2, 7.3±5.2, 7.2±11.6, 4.5±2.3, and 8.7±4.6 seconds at BL1, day1, 2, 4, and BL2, respectively) were found. Schirmer test changes at high altitude remained statistically nonsignificant compared to baseline. Comparisons of parameters between BL1 and BL2 showed no statistically significant differences and recordings of right and left eyes for TBUT and Schirmer did not differ significantly on any day measured. Conclusion: High altitude exposure leads to an altered tear film resulting in an increased TFO and a reduced TBUT. These changes were fully reversible after descent. This is of clinical importance to populations living in high altitude areas and to trekkers and mountaineers exposed to high altitude due to their ever-increasing number. PMID:24971769

Willmann, Gabriel; Schatz, Andreas; Fischer, M Dominik; Schommer, Kai; Zrenner, Eberhart; Bartz-Schmidt, Karl U; Gekeler, Florian; Gekeler, Katrin

2014-06-01

95

Neurodevelopmental alcohol exposure elicits long-term changes to gene expression that alter distinct molecular pathways dependent on timing of exposure  

PubMed Central

Background Maternal alcohol consumption is known to adversely affect fetal neurodevelopment. While it is known that alcohol dose and timing play a role in the cognitive and behavioral changes associated with prenatal alcohol exposure, it is unclear what developmental processes are disrupted that may lead to these phenotypes. Methods Mice (n=6 per treatment per developmental time) were exposed to two acute doses of alcohol (5 g/kg) at neurodevelopmental times representing the human first, second, or third trimester equivalent. Mice were reared to adulthood and changes to their adult brain transcriptome were assessed using expression arrays. These were then categorized based on Gene Ontology annotations, canonical pathway associations, and relationships to interacting molecules. Results The results suggest that ethanol disrupts biological processes that are actively occurring at the time of exposure. These include cell proliferation during trimester one, cell migration and differentiation during trimester two, and cellular communication and neurotransmission during trimester three. Further, although ethanol altered a distinct set of genes depending on developmental timing, many of these show interrelatedness and can be associated with one another via ‘hub’ molecules and pathways such as those related to huntingtin and brain-derived neurotrophic factor. Conclusions These changes to brain gene expression represent a ‘molecular footprint’ of neurodevelopmental alcohol exposure that is long-lasting and correlates with active processes disrupted at the time of exposure. This study provides further support that there is no neurodevelopmental time when alcohol cannot adversely affect the developing brain.

2013-01-01

96

Increases in Retrospective Accounts of War-Zone Exposure Over Time: The Role of PTSD Symptom Severity  

Microsoft Academic Search

Retrospective reports of the frequency of war-zone exposure are commonly used as objective indices in studies investigating the mental health consequences of exposure to such stressors. To explore the temporal stability of these types of reports, we obtained frequency estimates of exposure to war-zone stressors at two time points from 460 U.S. soldiers who had served in the peace-keeping mission

Lizabeth Roeraer; Brett T. Litz; Susan M. Orsillo; Peter J. Ehlich; Matthew J. Friedman

1998-01-01

97

Time allocation shifts and pollutant exposure due to traffic congestion: an analysis using the national human activity pattern survey.  

PubMed

Traffic congestion increases air pollutant exposures of commuters and urban populations due to the increased time spent in traffic and the increased vehicular emissions that occur in congestion, especially "stop-and-go" traffic. Increased time in traffic also decreases time in other microenvironments, a trade-off that has not been considered in previous time activity pattern (TAP) analyses conducted for exposure assessment purposes. This research investigates changes in time allocations and exposures that result from traffic congestion. Time shifts were derived using data from the National Human Activity Pattern Survey (NHAPS), which was aggregated to nine microenvironments (six indoor locations, two outdoor locations and one transport location). After imputing missing values, handling outliers, and conducting other quality checks, these data were stratified by respondent age, employment status and period (weekday/weekend). Trade-offs or time-shift coefficients between time spent in vehicles and the eight other microenvironments were then estimated using robust regression. For children and retirees, congestion primarily reduced the time spent at home; for older children and working adults, congestion shifted the time spent at home as well as time in schools, public buildings, and other indoor environments. Changes in benzene and PM(2.5) exposure were estimated for the current average travel delay in the U.S. (9 min day(-1)) and other scenarios using the estimated time shifts coefficients, concentrations in key microenvironments derived from the literature, and a probabilistic analysis. Changes in exposures depended on the duration of the congestion and the pollutant. For example, a 30 min day(-1) travel delay was determined to account for 21+/-12% of current exposure to benzene and 14+/-8% of PM(2.5) exposure. The time allocation shifts and the dynamic approach to TAPs improve estimates of exposure impacts from congestion and other recurring events. PMID:19683333

Zhang, Kai; Batterman, Stuart A

2009-10-15

98

Comparison of bioassays with different exposure time patterns: the added value of dynamic modelling in predictive ecotoxicology.  

PubMed

The purpose of this study was to compare Daphnia magna responses to cadmium between two toxicity experiments performed in static and flow-through conditions. As a consequence of how water was renewed, the two experiments were characterised by two different exposure time patterns for daphnids, time-varying and constant, respectively. Basing on survival, growth and reproduction, we addressed the questions of organism development and sensitivity to cadmium. Classical analysis methods are not designed to deal with the time dimension and therefore not suitable to compare effects of different exposure time patterns. We used instead a dynamic modelling framework taking all timepoints and the time course of exposure into account, making comparable the results obtained from our two experiments. This modelling framework enabled us to detect an improvement of organism development in flow-through conditions compared to static ones and infer similar sensitivity to cadmium for both exposure time patterns. PMID:21889211

Billoir, Elise; Delhaye, Hèlène; Forfait, Carole; Clément, Bernard; Triffault-Bouchet, Gaëlle; Charles, Sandrine; Delignette-Muller, Marie Laure

2012-01-01

99

HO-1 and VEGF gene expressions are time dependant during exposure to welding fumes.  

PubMed

Hemeoxygenase-1 (HO-1) is a defensive enzyme against oxidative stress. Vascular epithelial growth factor (VEGF) is a potent cytokine which promotes angiogenesis. We used induced sputum (IS) technology to study HO-1 and VEGF expressions in neutrophilic inflammation in asymptomatic welders. Aircraft plant employees were divided into three groups: Welders 1 (n=30) had short-term exposure to aluminum/iron, Welders 2 (n=16) had long-term exposure to cadmium/chromium/iron/nickel, and controls (n=27 non-exposed individuals). Participants underwent pulmonary function tests (PFTs), IS, differential cell counts, and determination of particle size distribution in IS samples. HO-1 and VEGF gene expressions were analyzed by real-time polymerase chain reaction, and protein levels were measured by bilirubin reductase-dependant reaction and ELISA, respectively. All subjects had normal PFTs. Welders 2 had neutrophilic inflammation and higher percentages of particles between 2-5 micron than the other groups. HO-1 inversely correlated with VEGF gene expression: HO-1 was significantly higher and VEGF was significantly lower in the Welders 1 group than in the other groups. There was a correlation between HO-1 expression and protein activity (r=0.33, P=0.05). Particulate matters significantly influenced HO-1 and VEGF gene expressions, caused neutrophilic inflammation and promoted oxidative stress in welders with long-term exposure. PMID:19303319

Stark, M; Zubareb, J; Jacovovitz, R; Schwartz, Y; Lerman, Y; Grinberg, N; Fireman, E

2009-05-01

100

Constructing a time series for large landslides in Trentino (Italy) with 36Cl exposure dating  

NASA Astrophysics Data System (ADS)

The Trentino province of NE Italy is characterized by numerous large landslides and rock avalanche deposits, notably in valleys that are rather densely inhabited. One may gain fundamental information for calculation of return times of slope collapses by surface exposure dating of boulders and scarp area bedrock. First investigations focus on the following landslides: Lavini di Marco (covering an area of 15.7 km2), Marocche di Dro (8.1 km2), Molveno (5.0 km2); Palone (2.5 km2), Castelpietra (0.4 km2), Marzola (12.5 km2). Field surveys that indicate multi-phase activity serve as a basis for sampling. Cosmogenic 36Cl was used due to the predominance of limestone and dolomite. In this presentation, interpretation of (in some cases scattered) age distributions at individual sites will be discussed, especially the frequency of pre-exposure. The distribution in time of the Trentino, mass movement events will be considered in light of what is known about paleoseismicity in the region, the timing of other large landslides in the Alps, and the sequence of climate variations during the Holocene.

Ivy-Ochs, S.; Martin, S.; Campedel, P.; Alfimov, V.; Andreotti, E.; Viganò, A.; Carugati, G.; Vockenhuber, C.; Cocco, S.

2012-04-01

101

Gene expression-based dosimetry by dose and time in mice following acute radiation exposure.  

PubMed

Rapid and reliable methods for performing biological dosimetry are of paramount importance in the event of a large-scale nuclear event. Traditional dosimetry approaches lack the requisite rapid assessment capability, ease of use, portability and low cost, which are factors needed for triaging a large number of victims. Here we describe the results of experiments in which mice were acutely exposed to (60)Co gamma rays at doses of 0 (control) to 10 Gy. Blood was obtained from irradiated mice 0.5, 1, 2, 3, 5, and 7 days after exposure. mRNA expression levels of 106 selected genes were obtained by reverse-transcription real time PCR. Stepwise regression of dose received against individual gene transcript expression levels provided optimal dosimetry at each time point. The results indicate that only 4-7 different gene transcripts are needed to explain ? 0.69 of the variance (R(2)), and that receiver-operator characteristics, a measure of sensitivity and specificity, of ? 0.93 for these statistical models were achieved at each time point. These models provide an excellent description of the relationship between the actual and predicted doses up to 6 Gy. At doses of 8 and 10 Gy there appears to be saturation of the radiation-response signals with a corresponding diminution of accuracy. These results suggest that similar analyses in humans may be advantageous for use in a field-portable device designed to assess exposures in mass casualty situations. PMID:24358280

Tucker, James D; Divine, George W; Grever, William E; Thomas, Robert A; Joiner, Michael C; Smolinski, Joseph M; Auner, Gregory W

2013-01-01

102

Self-reported exertion levels on time/activity diaries: application to exposure assessment  

SciTech Connect

Recent developments in air pollution analysis have focused on methods for collecting data on contaminant levels in the locations actually frequented by people, especially personal monitoring. While there is still much to understand about human exposures, the next advancements will be in the area of dose assessment. This paper discusses the results of a study designed to provide data for linking exposure to dose. Specifically, we used time/activity diaries to collect information on the exertion levels associated with the reported activities. As part of a community health study, 91 children between the ages of 9 and 11 kept diaries over a two-week summer-time period (July 1989) and during a two-week school-time period (September 1989). The diary was also administered for two days to 42 teenagers between the ages of 15 and 17. This paper describes our concerns about interpreting self-reported exertion levels, particularly with respect to the disparity between participant and researcher perception and coding. We then present the distribution of exertion levels associated with children's activities, highlighting seasonal, day-of-week, and age-group differences.

Schwab, M.; Terblanche, A.P.; Spengler, J.D. (Harvard School of Public Health, Department of Environmental Health, Boston, MA (United States))

1991-07-01

103

Bayesian modelling of daphnid responses to time-varying cadmium exposure in laboratory aquatic microcosms.  

PubMed

Experiments were carried out to test the effects of cadmium on five aquatic species in 2-L indoor freshwater/sediment microcosms. Experimental data were collected over 21 days in static conditions, i.e. the microcosms evolved without water renewal. Because of speciation, the total cadmium concentration in water decreased with time. Here we present a focus on Daphnia magna responses. For the three life history traits we considered (survival, growth and reproduction), mathematical effect models were built based on threshold stress functions involving no effect concentrations (NECs). These models took the time-varying conditions of exposure into account through a time-recurrent formalism. Within a Bayesian framework, four kinds of data were fitted simultaneously (exposure, survival, growth and reproduction), using an appropriate error model for each endpoint. Hence, NECs were determined as well as their associated estimation uncertainty. Through this modelling approach, we demonstrate that thresholds for stress functions can be successfully inferred even in experimental setup more complex than standard bioassays. PMID:21056469

Billoir, Elise; Delhaye, Hélène; Clément, Bernard; Delignette-Muller, Marie Laure; Charles, Sandrine

2011-05-01

104

Space Weathering Effects in Lunar Soils: The Roles of Surface Exposure Time and Bulk Chemical Composition  

NASA Technical Reports Server (NTRS)

Space weathering effects on lunar soil grains result from both radiation-damaged and deposited layers on grain surfaces. Typically, solar wind irradiation forms an amorphous layer on regolith silicate grains, and induces the formation of surficial metallic Fe in Fe-bearing minerals [1,2]. Impacts into the lunar regolith generate high temperature melts and vapor. The vapor component is largely deposited on the surfaces of lunar soil grains [3] as is a fraction of the melt [4, this work]. Both the vapor-deposits and the deposited melt typically contain nanophase Fe metal particles (npFe0) as abundant inclusions. The development of these rims and the abundance of the npFe0 in lunar regolith, and thus the optical properties, vary with the soil mineralogy and the length of time the soil grains have been exposed to space weathering effects [5]. In this study, we used the density of solar flare particle tracks in soil grains to estimate exposure times for individual grains and then perform nanometer-scale characterization of the rims using transmission electron microscopy (TEM). The work involved study of lunar soil samples with different mineralogy (mare vs. highland) and different exposure times (mature vs. immature).

Zhang, Shouliang; Keller, Lindsay P.

2011-01-01

105

Influence of paternal exposure to oil and oil products on time to pregnancy and spontaneous abortions.  

PubMed

The objective of this study was to evaluate the influence of exposure to oil and oil products among men on the time taken for their wives to conceive and on the incidence of spontaneous abortion among them. A cross-sectional study was performed by posting questionnaires to 1,269 men employed as offshore mechanics, offshore operators, offshore drilling personnel, car mechanics (the 'exposed' occupations) and carpenters ('unexposed'). The married men were asked to give a separate questionnaire to their wives for details about their pregnancies. The time elapsed between the beginning of coitus without contraception and the wife becoming pregnant (time to pregnancy) was analyzed with Cox regression analysis by calculating fecundability ratios for the pregnancies for the men exposed to oil and oil products as compared with the men who were not exposed. Spontaneous abortions were analyzed with logistic regression by calculating odds ratios for the pregnancies in which the men were exposed vs. not exposed. A total of 741 (58%) men returned the questionnaires. A total of 301 pregnancies were analyzed for time taken to conceive and 580 for spontaneous abortion. The results were adjusted for variables that could significantly influence conception time (previous infections of the reproductive system and coffee drinking) or the incidence of spontaneous abortion (mother's age, parity and smoking). The outcomes between the exposed and unexposed pregnancies showed no significant differences. Car mechanics had a lower fecundability ratio before 1992 than after 1992. Paternal exposure to hydrocarbons in the occupations studied did not seem to have had a major influence on time to conception or the incidence of spontaneous abortion among the wives of the men exposed to oil products. PMID:10628044

Bull, N; Riise, T; Moen, B E

1999-08-01

106

REAL-TIME MODELING AND MEASUREMENT OF MOBILE SOURCE POLLUTANT CONCENTRATIONS FOR ESTIMATING HUMAN EXPOSURES IN COMMUNITIES NEAR ROADWAYS  

EPA Science Inventory

The United States Environmental Protection Agency's (EPA) National Exposure Research Laboratory (NERL) is pursuing a project to improve the methodology for real-time site specific modeling of human exposure to pollutants from motor vehicles. The overall project goal is to deve...

107

Development of the town data base: Estimates of exposure rates and times of fallout arrival near the Nevada Test Site.  

National Technical Information Service (NTIS)

As part of the U.S. Department of Energy's Off-Site Radiation Exposure Review Project, the time of fallout arrival and the H+12 exposure rate were estimated for populated locations in Arizona, California, Nevada, and Utah that were affected by fallout fro...

C. B. Thompson R. D. McArthur S. W. Hutchinson

1994-01-01

108

The interactive effects of chytrid fungus, pesticides, and exposure timing on gray treefrog (Hyla versicolor) larvae.  

PubMed

Aquatic organisms are often exposed to a wide variety of perturbations in nature, including pathogens and chemical contaminants. Despite the co-occurrence of these 2 stressors, few studies have examined the effects of chemical contaminants on host-pathogen dynamics. The authors tested the individual and combined effects on gray treefrog (Hyla versicolor) tadpoles of 2 commonly used pesticides (Roundup® and Sevin®) and the pathogenic fungus Batrachochytrium dendrobatidis (Bd). A fully factorial design was used, and tadpoles were exposed to Bd, Roundup, or Sevin alone, or a combination of Bd and either pesticide at 3 points during larval development (early, mid, late). It was predicted that pesticides would mediate the effect of Bd on tadpoles and reduce the likelihood of negative consequences of infection and that timing of exposure would influence these effects. Tadpoles exposed to Bd at the mid point experienced higher survival through metamorphosis than those exposed to Bd at the early or late points, while tadpoles exposed to Sevin at the early point experienced reduced survival compared with those exposed to Roundup or no-pesticide control at the same exposure point. Roundup ameliorated the effects of Bd on survival compared with tadpoles exposed to Bd alone, while there was no interactive effect of Sevin on survival. In addition, Sevin reduced mass of new metamorphs compared with Roundup and reduced snout-vent length compared with all other treatments. The present study supports the hypothesis that pesticides can mitigate the effects of Bd on amphibian hosts and that such effects may depend on the timing of exposure. PMID:24259231

Hanlon, Shane M; Parris, Matthew J

2014-01-01

109

Concentration-time exposure index for modeling soil fumigation under various management scenarios.  

PubMed

Best management decisions in soil fumigation require informed management selections of soil type, field geometry, application dosage, and depth to maximize fumigant distribution for efficacy and minimize off-site transport for environmental safety. An efficacy- or exposure-based concentration-time exposure index (CTEI) was used to serve as a continuous quantitative efficacy assessment for soil fumigation by subsurface drip irrigation using numerical model simulations. The CTEI was defined as the ratio between the soil volume where concentration-time (CT) exceeded a threshold value for a particular pest-fumigant combination and the total soil volume required for fumigation treatment. Applications of CTEI as a simple efficacy index were demonstrated by simulating combinations of three soil types (loam, sandy loam, sand); three field configurations consisting of 102- and 203-cm-wide bed systems and a flat surface system; three application depths (15, 30, 45 cm); and two application rates (82 and 327 kg ha(-1)) for 1,3-dichloropropene against citrus nematode (Tylenchulus semipenetrans) using a threshold air-phase CT value of 12 microg h cm(-3) obtained from a separate field study. For soil fumigation by subsurface drip irrigation, the order of importance in optimizing CTEI was soil type, depth of application and depth of treatment, dosage, and field configuration. Model simulation using CTEI as a numeric efficacy index can be an effective alternative to assist in the planning of field trials for making final management decisions concerning soil fumigation or other pesticide applications. PMID:15074821

Wang, D; He, J M; Knuteson, J A

2004-01-01

110

Real-time imaging of membrane potentials during exposure to nanosecond pulsed electric fields  

NASA Astrophysics Data System (ADS)

The charging of mammalian cell plasma membranes in response to ultrashort pulsed electric fields of 60 ns and field strengths up to 100 kV/cm was investigated. Membranes of Jurkat cells were stained with a potential-sensitive dye, Annine-6 and placed in a microreactor mounted on an inverted fluorescence microscope. Images of changes in the fluorescence intensity during the exposure were recorded with a high-sensitivity CCD-camera. A temporal resolution of 5 ns was achieved by illuminating the cells with a 5 ns laser pulse from a dye-laser. The laser pulse was synchronized with the high voltage pulse to record images at specific times before, during and after exposure to the electric field. When exposing Jurkat cells to a 60 ns, 100 kV/cm pulse, each hemisphere of the plasma membrane (as oriented with respect to the electrodes) responded uniquely to the applied field. From these observations it is possible to draw conclusions on the charging time of the membrane, maximum transmembrane voltages and the onset of poration.

Kolb, Juergen F.; Frey, Wolfgang; White, Jody A.; Price, R. O.; Blackmore, Peter F.; Beebe, Stephen J.; Joshi, Ravindra P.; Schoenbach, Karl H.

2005-04-01

111

Short time exposure to hydrogen peroxide induces sustained glutathione export from cultured neurons.  

PubMed

Hydrogen peroxide is a normal by-product of cellular metabolism that in higher concentrations can cause oxidative stress. Cultured cerebellar granule neurons efficiently disposed of micromolar concentrations of hydrogen peroxide with half-times in the minute range in a process that predominately involved catalase. Application of up to 100µM hydrogen peroxide did not affect the cell viability for up to 4h, but caused a time- and concentration-dependent increase in the extracellular glutathione (GSH) content that was accompanied by a matching decrease in the cellular GSH content. Hydrogen peroxide at 100µM stimulated maximally the GSH export from viable neurons, but did not affect GSH export from cultured astrocytes. The peroxide-induced extracellular GSH accumulation from neurons was lowered by 70% in the presence of MK571, an inhibitor of multidrug resistance protein (Mrp) 1. The extracellular GSH content determined after 4h of incubation was already significantly increased after a 5-min exposure of neurons to hydrogen peroxide and became maximal after 15min of peroxide application. These data demonstrate that just a short exposure of viable cerebellar granule neurons to micromolar concentrations of hydrogen peroxide stimulates a prolonged Mrp1-mediated export of cellular GSH. This process may compromise the antioxidative potential of neurons and increase their sensitivity toward drugs and toxins. PMID:24524999

Hohnholt, Michaela C; Dringen, Ralf

2014-05-01

112

Validation of exposure time for discharge measurements made with two bottom-tracking acoustic doppler current profilers  

USGS Publications Warehouse

Previous work by Oberg and Mueller of the U.S. Geological Survey in 2007 concluded that exposure time (total time spent sampling the flow) is a critical factor in reducing measurement uncertainty. In a subsequent paper, Oberg and Mueller validated these conclusions using one set of data to show that the effect of exposure time on the uncertainty of the measured discharge is independent of stream width, depth, and range of boat speeds. Analysis of eight StreamPro acoustic Doppler current profiler (ADCP) measurements indicate that they fall within and show a similar trend to the Rio Grande ADCP data previously reported. Four special validation measurements were made for the purpose of verifying the conclusions of Oberg and Mueller regarding exposure time for Rio Grande and StreamPro ADCPs. Analysis of these measurements confirms that exposure time is a critical factor in reducing measurement uncertainty and is independent of stream width, depth, and range of boat speeds. Furthermore, it appears that the relation between measured discharge uncertainty and exposure time is similar for both Rio Grande and StreamPro ADCPs. These results are applicable to ADCPs that make use of broadband technology using bottom-tracking to obtain the boat velocity. Based on this work, a minimum of two transects should be collected with an exposure time for all transects greater than or equal to 720 seconds in order to achieve an uncertainty of ??5 percent when using bottom-tracking ADCPs. ?? 2008 IEEE.

Czuba, J. A.; Oberg, K.

2008-01-01

113

Motor response programming and movement time in children with heavy prenatal alcohol exposure.  

PubMed

The present experiment assessed motor response programming and movement time in children with histories of heavy prenatal alcohol exposure (PEA). Alcohol-exposed children between the ages of 7 and 17 years were classified into two groups: Fetal Alcohol Syndrome (FAS: n=9) and children with PEA (PEA: n=19) but who did not have the defining characteristics of FAS. The FAS and PEA children were compared with non-alcohol-exposed children (NC: n=23) when completing two tasks: a simple reaction time task (RT alone condition) and a reaction plus movement task (RT+Move condition). The movement involved responding to an imperative stimulus signal and depressing three target buttons in a set sequence. Participants completed 24 trials each for the RT alone and RT+Move response conditions. Results indicated no significant differences in performance among FAS, PEA, and NC groups during the RT alone condition. However, during the RT+Move condition, the FAS group produced significantly longer and more variable RTs than the PEA and NC groups, which produced comparable RTs. The FAS group also produced significantly slower movement times when moving to all three targets, whereas movement time variability did not significantly differ as a function of group. The observed results indicate children with FAS experience deficits in response programming and movement time production. PMID:20598488

Simmons, Roger W; Thomas, Jennifer D; Levy, Susan S; Riley, Edward P

2010-06-01

114

Time-averaged exposures to sup 220 Rn and sup 222 Rn progeny in Colorado homes  

SciTech Connect

Week-long time-averaged exposures to naturally occurring {sup 220}Rn and {sup 222}Rn progeny have been measured at several locations in Colorado by monitoring the alpha activity collected continuously on a fixed-membrane filter. The alpha-energy spectrum associated with the activity collected on the filter was recorded every 15 min using a microcomputer-controlled alpha spectrometer. The alpha counts observed in three energy regions permitted complete separation of the contributions from each decay chain, and calculation of the separate time-averaged potential alpha-energy concentrations in air from {sup 220}Rn progeny, PAEC(Tn), and from {sup 222}Rn progeny, PAEC(Rn). The time-averaged PAEC(Tn) ranged from 0.3 to 6.9 mWL at 12 indoor locations, and the time-averaged PAEC(Rn) ranged from 1.0 to 59.0 mWL. The ratios of the indoor PAEC(Tn) to indoor PAEC(Rn) ranged from 0.09 to 0.58, with an overall average ratio of 0.32 and a standard deviation of 0.15. The 10 L min-1 flow rate through the filter was selected to approximate the air intake rate of a resting human; the time-averaged PAEC thus represents the progeny concentrations that would have been inhaled by a person breathing the same atmosphere.

Martz, D.E.; Falco, R.J.; Langner, G.H. Jr. (Department of Energy, Grand Junction Projects Office, CO (USA))

1990-06-01

115

Uncertainty and variability in historical time-weighted average exposure data.  

PubMed

Beginning around 1940, private companies began processing of uranium and thorium ore, compounds, and metals for the Manhattan Engineer District and later the U.S. Atomic Energy Commission (AEC). Personnel from the AEC's Health and Safety Laboratory (HASL) visited many of the plants to assess worker exposures to radiation and radioactive materials. They developed a time-and-task approach to estimating "daily weighted average" (DWA) concentrations of airborne uranium, thorium, radon, and radon decay products. While short-term exposures greater than 10(5) dpm m(-3) of uranium and greater than 10(5) pCi L(-1) of radon were observed, DWA concentrations were much lower. The HASL-reported DWA values may be used as inputs for dose reconstruction in support of compensation decisions, but they have no numerical uncertainties associated with them. In this work, Monte Carlo methods are used retrospectively to assess the uncertainty and variability in the DWA values for 63 job titles from five different facilities that processed U, U ore, Th, or 226Ra-222Rn between 1948 and 1955. Most groups of repeated air samples are well described by lognormal distributions. Combining samples associated with different tasks often results in a reduction of the geometric standard deviation (GSD) of the DWA to less than those GSD values typical of individual tasks. Results support the assumption of a GSD value of 5 when information on uncertainty in DWA exposures is unavailable. Blunders involving arithmetic, transposition, and transcription are found in many of the HASL reports. In 5 out of the 63 cases, these mistakes result in overestimates of DWA values by a factor of 2 to 2.5, and in 2 cases DWA values are underestimated by factors of 3 to 10. PMID:18188049

Davis, Adam J; Strom, Daniel J

2008-02-01

116

In-situ hydrogen in metal determination using a minimum neutron source strength and exposure time.  

PubMed

Water is frequently present in the environment and is a source of hydrogen that can interact with many materials. Because of its small atomic size, a hydrogen atom can easily diffuse into a host metal, and though the metal may appear unchanged for a time, the metal will eventually abruptly lose its strength and ductility. Thus, measuring the hydrogen content in metals is important in many fields, such as in the nuclear industry, in automotive and aircraft fabrication, and particularly, in offshore oil and gas fields. It has been demonstrated that the use of nuclear methods to measure the hydrogen content in metals can achieve sensitivity levels on the order of parts per million. However, the use of nuclear methods in the field has not been conducted for two reasons. The first reason is due to exposure limitations. The second reason is due to the hi-tech instruments required for better accuracy. In this work, a new method using a low-strength portable neutron source is explored in conjunction with detectors based on plastic nuclear detection films. The following are the in-situ requirements: simplicity in setup, high reliability, minimal exposure dose, and acceptable accuracy at an acceptable cost. A computer model of the experimental setup is used to reproduce the results of a proof-of-concept experiment and to predict the sensitivity levels under optimised experimental conditions. PMID:23708832

Hatem, M; Agamy, S; Khalil, M Y

2013-08-01

117

GPS-based Microenvironment Tracker (MicroTrac) Model to Estimate Time-Location of Individuals for Air Pollution Exposure Assessments: Model Evaluation in Central North Carolina  

EPA Science Inventory

A critical aspect of air pollution exposure assessment is the estimation of the time spent by individuals in various microenvironments (ME). Accounting for the time spent in different ME with different pollutant concentrations can reduce exposure misclassifications, while failure...

118

Human short-term exposure to electromagnetic fields emitted by mobile phones decreases computer-assisted visual reaction time.  

PubMed

The worldwide dramatic increase in mobile phone use has generated great concerns about the detrimental effects of microwave radiations emitted by these communication devices. Reaction time plays a critical role in performing tasks necessary to avoid hazards. As far as we know, this study is the first survey that reports decreased reaction time after exposure to electromagnetic fields generated by a high specific absorption rate mobile phone. It is also the first study in which previous history of mobile phone use is taken into account. The aim of this study was to assess both the acute and chronic effects of electromagnetic fields emitted by mobile phones on reaction time in university students. Visual reaction time (VRT) of young university students was recorded with a simple blind computer-assisted-VRT test, before and after a 10 min real/sham exposure to electromagnetic fields of mobile phones. Participants were 160 right-handed university students aged 18-31. To assess the effect of chronic exposures, the reaction time in sham-exposed phases were compared among low level, moderate and frequent users of mobile phones. The mean ± SD reaction time after real exposure and sham exposure were 286.78 ± 31.35 ms and 295.86 ± 32.17 ms (P < 0.001), respectively. The age of students did not significantly alter the reaction time either in talk or in standby mode. The reaction time either in talk or in standby mode was shorter in male students. The students' VRT was significantly affected by exposure to electromagnetic fields emitted by a mobile phone. It can be concluded that these exposures cause decreased reaction time, which may lead to a better response to different hazards. In this light, this phenomenon might decrease the chances of human errors and fatal accidents. PMID:22426673

Mortazavi, S M J; Rouintan, M S; Taeb, S; Dehghan, N; Ghaffarpanah, A A; Sadeghi, Z; Ghafouri, F

2012-06-01

119

Asbestos disease at low exposure after long residence time in amphibole miners  

Microsoft Academic Search

Short reports of several studies carried out in South Africa which have a bearing on the health effects of low exposures to asbestos are presented. It is stressed that the findings refer solely to amphibole asbestos. Average fiber exposure of 1 or less or a cumulative exposure of less than 2-5 fibers\\/ml years is associated with the development of asbestosis

Sluis-Cremer

1991-01-01

120

Spectral (600-1050 nm) time exposures (99.6 ?s) of a lightning stepped leader  

NASA Astrophysics Data System (ADS)

A cloud-to-ground lightning stepped leader has been recorded with a slitless spectrograph at a recording rate of 10,000 images per second at a distance of 0.6 km. Five sequential images of the leader spectra were recorded with an exposure (integration) time of 99.6 ?s each over a spectral range from 600 to 1050 nm. These are the first stepped leader spectra covering the range 600 to 1050 nm. The last three spectra, obtained immediately before the return stroke, were analyzed at an altitude of between 108 and 122 m above a struck vehicle. The spectral emissions in the near infrared are dominated by neutral nitrogen and oxygen emissions, and H?, with only a few emission lines from singly ionized nitrogen. A singly ionized nitrogen line at 661.1 nm is present in the first analyzed image, but not in the two subsequent images at the same height, which suggests a cooling of the channel. The emissions are integrated over a 99.6 ?s exposure time and therefore show no evidence of stepping. The ensuing negative return stroke was detected by the National Lightning Detection Network and had an estimated peak current of -15.2 kA. One subsequent stroke was outside the field of view of the spectrograph. The flash occurred on 11 September 2009 near New Underwood, South Dakota, and the exact location of the first stroke is known because it struck a car traveling on Interstate 90. The stepped leader two-dimensional speed increased in the last four steps from 1.53 × 105 to 2.42 × 105 m/s with an average of 2.03 × 105 m/s.

Warner, Tom A.; Orville, Richard E.; Marshall, J. L.; Huggins, Kyle

2011-06-01

121

Dose, exposure time and resolution in serial X-ray crystallography.  

PubMed

The resolution of X-ray diffraction microscopy is limited by the maximum dose that can be delivered prior to sample damage. In the proposed serial crystallography method, the damage problem is addressed by distributing the total dose over many identical hydrated macromolecules running continuously in a single-file train across a continuous X-ray beam, and resolution is then limited only by the available molecular and X-ray fluxes and molecular alignment. Orientation of the diffracting molecules is achieved by laser alignment. The incident X-ray fluence (energy/area) is evaluated that is required to obtain a given resolution from (i) an analytical model, giving the count rate at the maximum scattering angle for a model protein, (ii) explicit simulation of diffraction patterns for a GroEL-GroES protein complex, and (iii) the spatial frequency cut-off of the transfer function following iterative solution of the phase problem, and reconstruction of an electron density map in the projection approximation. These calculations include counting shot noise and multiple starts of the phasing algorithm. The results indicate counting time and the number of proteins needed within the beam at any instant for a given resolution and X-ray flux. An inverse fourth-power dependence of exposure time on resolution is confirmed, with important implications for all coherent X-ray imaging. It is found that multiple single-file protein beams will be needed for sub-nanometer resolution on current third-generation synchrotrons, but not on fourth-generation designs, where reconstruction of secondary protein structure at a resolution of 7 A should be possible with relatively short exposures. PMID:18097080

Starodub, D; Rez, P; Hembree, G; Howells, M; Shapiro, D; Chapman, H N; Fromme, P; Schmidt, K; Weierstall, U; Doak, R B; Spence, J C H

2008-01-01

122

Exposures to Synthetic Estrogens at Different Times During the Life, and Their Effect on Breast Cancer Risk  

PubMed Central

Women are using estrogens for many purposes, such as to prevent pregnancy or miscarriage, or to treat menopausal symptoms. Estrogens also have been used to treat breast cancer which seems puzzling, since there is convincing evidence to support a link between high lifetime estrogen exposure and increased breast cancer risk. In this review, we discuss the findings that maternal exposure to the synthetic estrogen diethylstilbestrol during pregnancy increases breast cancer risk in both exposed mothers and their daughters. In addition, we review data regarding the use of estrogens in oral contraceptives and as postmenopausal hormone therapy and discuss the opposing effects on breast cancer risk based upon timing of exposure. We place particular emphasis on studies investigating how maternal estrogenic exposures during pregnancy increase breast cancer risk among daughters. New data suggest that these exposures induce epigenetic modifications in the mammary gland and germ cells, thereby causing an inheritable increase in breast cancer risk for multiple generations.

de Assis, Sonia; Warri, Anni

2013-01-01

123

Exposures to synthetic estrogens at different times during the life, and their effect on breast cancer risk.  

PubMed

Women are using estrogens for many purposes, such as to prevent pregnancy or miscarriage, or to treat menopausal symptoms. Estrogens also have been used to treat breast cancer which seems puzzling, since there is convincing evidence to support a link between high lifetime estrogen exposure and increased breast cancer risk. In this review, we discuss the findings that maternal exposure to the synthetic estrogen diethylstilbestrol during pregnancy increases breast cancer risk in both exposed mothers and their daughters. In addition, we review data regarding the use of estrogens in oral contraceptives and as postmenopausal hormone therapy and discuss the opposing effects on breast cancer risk based upon timing of exposure. We place particular emphasis on studies investigating how maternal estrogenic exposures during pregnancy increase breast cancer risk among daughters. New data suggest that these exposures induce epigenetic modifications in the mammary gland and germ cells, thereby causing an inheritable increase in breast cancer risk for multiple generations. PMID:23392570

Hilakivi-Clarke, Leena; de Assis, Sonia; Warri, Anni

2013-03-01

124

Comparison of nested case-control and survival analysis methodologies for analysis of time-dependent exposure  

PubMed Central

Background Epidemiological studies of exposures that vary with time require an additional level of methodological complexity to account for the time-dependence of exposure. This study compares a nested case-control approach for the study of time-dependent exposure with cohort analysis using Cox regression including time-dependent covariates. Methods A cohort of 1340 subjects with four fixed and seven time-dependent covariates was used for this study. Nested case-control analyses were repeated 100 times for each of 4, 8, 16, 32, and 64 controls per case, and point estimates were compared to those obtained using Cox regression on the full cohort. Computational efficiencies were evaluated by comparing central processing unit times required for analysis of the cohort at sizes 1, 2, 4, 8, 16, and 32 times its initial size. Results Nested case-control analyses yielded results that were similar to results of Cox regression on the full cohort. Cox regression was found to be 125 times slower than the nested case-control approach (using four controls per case). Conclusions The nested case-control approach is a useful alternative for cohort analysis when studying time-dependent exposures. Its superior computational efficiency may be particularly useful when studying rare outcomes in databases, where the ability to analyze larger sample sizes can improve the power of the study.

Essebag, Vidal; Platt, Robert W; Abrahamowicz, Michal; Pilote, Louise

2005-01-01

125

Estimating the Time Interval Between Exposure to the World Trade Center Disaster and Incident Diagnoses of Obstructive Airway Disease  

PubMed Central

Respiratory disorders are associated with occupational and environmental exposures. The latency period between exposure and disease onset remains uncertain. The World Trade Center (WTC) disaster presents a unique opportunity to describe the latency period for obstructive airway disease (OAD) diagnoses. This prospective cohort study of New York City firefighters compared the timing and incidence of physician-diagnosed OAD relative to WTC exposure. Exposure was categorized by WTC arrival time as high (on the morning of September 11, 2001), moderate (after noon on September 11, 2001, or on September 12, 2001), or low (during September 13–24, 2001). We modeled relative rates and 95% confidence intervals of OAD incidence by exposure over the first 5 years after September 11, 2001, estimating the times of change in the relative rate with change point models. We observed a change point at 15 months after September 11, 2001. Before 15 months, the relative rate for the high- versus low-exposure group was 3.96 (95% confidence interval: 2.51, 6.26) and thereafter, it was 1.76 (95% confidence interval: 1.26, 2.46). Incident OAD was associated with WTC exposure for at least 5 years after September 11, 2001. There were higher rates of new-onset OAD among the high-exposure group during the first 15 months and, to a lesser extent, throughout follow-up. This difference in relative rate by exposure occurred despite full and free access to health care for all WTC-exposed firefighters, demonstrating the persistence of WTC-associated OAD risk.

Glaser, Michelle S.; Webber, Mayris P.; Zeig-Owens, Rachel; Weakley, Jessica; Liu, Xiaoxue; Ye, Fen; Cohen, Hillel W.; Aldrich, Thomas K.; Kelly, Kerry J.; Nolan, Anna; Weiden, Michael D.; Prezant, David J.; Hall, Charles B.

2014-01-01

126

Estimating the time interval between exposure to the world trade center disaster and incident diagnoses of obstructive airway disease.  

PubMed

Respiratory disorders are associated with occupational and environmental exposures. The latency period between exposure and disease onset remains uncertain. The World Trade Center (WTC) disaster presents a unique opportunity to describe the latency period for obstructive airway disease (OAD) diagnoses. This prospective cohort study of New York City firefighters compared the timing and incidence of physician-diagnosed OAD relative to WTC exposure. Exposure was categorized by WTC arrival time as high (on the morning of September 11, 2001), moderate (after noon on September 11, 2001, or on September 12, 2001), or low (during September 13-24, 2001). We modeled relative rates and 95% confidence intervals of OAD incidence by exposure over the first 5 years after September 11, 2001, estimating the times of change in the relative rate with change point models. We observed a change point at 15 months after September 11, 2001. Before 15 months, the relative rate for the high- versus low-exposure group was 3.96 (95% confidence interval: 2.51, 6.26) and thereafter, it was 1.76 (95% confidence interval: 1.26, 2.46). Incident OAD was associated with WTC exposure for at least 5 years after September 11, 2001. There were higher rates of new-onset OAD among the high-exposure group during the first 15 months and, to a lesser extent, throughout follow-up. This difference in relative rate by exposure occurred despite full and free access to health care for all WTC-exposed firefighters, demonstrating the persistence of WTC-associated OAD risk. PMID:24980522

Glaser, Michelle S; Webber, Mayris P; Zeig-Owens, Rachel; Weakley, Jessica; Liu, Xiaoxue; Ye, Fen; Cohen, Hillel W; Aldrich, Thomas K; Kelly, Kerry J; Nolan, Anna; Weiden, Michael D; Prezant, David J; Hall, Charles B

2014-08-01

127

Influence of the Exposure Time after Removing of Covering Materials over Shading Tea Field on the Quality of Gyokuro  

NASA Astrophysics Data System (ADS)

We revealed the influences of the exposure time after removing of covering materials over shading tea field for making gyokuro on the quality of made tea. As the exposure time increased, the green color of the fresh leaves faded; their total amino acid and theanine contents reduced; and the concentration of dimethyl sulfide, a representative aromatic compound in gyokuro, decreased. In contrast, the catechin content increased. The overall quality of the tea was lowered. These results indicated it was necessary to plucking of tea shoots for short time after removing of covering materials over shading tea field.

Sakaida, Teruki; Yoshioka, Tetsuya; Nitabaru, Juichi; Nakazono, Kentaro; Kubota, Akira; Nariyama, Hideki

128

Does oxygen exposure time control the extent of organic matter decomposition in peatlands?  

NASA Astrophysics Data System (ADS)

extent of peat decomposition was investigated in four cores collected along a latitudinal gradient from 56°N to 66°N in the West Siberian Lowland. The acid:aldehyde ratios of lignin phenols were significantly higher in the two northern cores compared with the two southern cores, indicating peats at the northern sites were more highly decomposed. Yields of hydroxyproline, an amino acid found in plant structural glycoproteins, were also significantly higher in northern cores compared with southern cores. Hydroxyproline-rich glycoproteins are not synthesized by microbes and are generally less reactive than bulk plant carbon, so elevated yields indicated that northern cores were more extensively decomposed than the southern cores. The southern cores experienced warmer temperatures, but were less decomposed, indicating that temperature was not the primary control of peat decomposition. The plant community oscillated between Sphagnum and vascular plant dominance in the southern cores, but vegetation type did not appear to affect the extent of decomposition. Oxygen exposure time appeared to be the strongest control of the extent of peat decomposition. The northern cores had lower accumulation rates and drier conditions, so these peats were exposed to oxic conditions for a longer time before burial in the catotelm, where anoxic conditions prevail and rates of decomposition are generally lower by an order of magnitude.

Philben, Michael; Kaiser, Karl; Benner, Ronald

2014-05-01

129

Near Real-Time Earthquake Exposure and Damage Assessment: An Example from Turkey  

NASA Astrophysics Data System (ADS)

Confined by infamous strike-slip North Anatolian Fault from the north and by the Hellenic subduction trench from the south Turkey is one of the most seismically active countries in Europe. Due this increased exposure and the fragility of the building stock Turkey is among the top countries exposed to earthquake hazard in terms of mortality and economic losses. In this study we focus recent and ongoing efforts to mitigate the earthquake risk in near real-time. We present actual results of recent earthquakes, such as the M6 event off-shore Antalya which occurred on 28 December 2013. Starting at the moment of detection, we obtain a preliminary ground motion intensity distribution based on epicenter and magnitude. Our real-time application is further enhanced by the integration of the SeisComp3 ground motion parameter estimation tool with the Earthquake Loss Estimation Routine (ELER). SeisComp3 provides the online station parameters which are then automatically incorporated into the ShakeMaps produced by ELER. The resulting ground motion distributions are used together with the building inventory to calculate expected number of buildings in various damage states. All these analysis are conducted in an automated fashion and are communicated within a few minutes of a triggering event. In our efforts to disseminate earthquake information to the general public we make extensive use of social networks such as Tweeter and collaborate with mobile phone operators.

Kamer, Yavor; Çomo?lu, Mustafa; Erdik, Mustafa

2014-05-01

130

A pilot study characterizing real time exposures to particulate matter and carbon monoxide from cookstove related woodsmoke in rural Peru  

NASA Astrophysics Data System (ADS)

Nearly half of the world's population is exposed to household air pollution (HAP) due to long hours spent in close proximity to unvented cooking fires. We aimed to use PM2.5 and CO measurements to characterize exposure to cookstove generated woodsmoke in real time among control (n = 10) and intervention (n = 9) households in San Marcos, Cajamarca Region, Peru. Real time personal particulate matter with an aerodynamic diameter ?2.5 ?m (PM2.5), and personal and kitchen carbon monoxide (CO) samples were taken. Control households used a number of stoves including open fire and chimney stoves while intervention households used study-promoted chimney stoves. Measurements were categorized into lunch (9 am-1 pm) and dinner (3 pm-7 pm) periods, where applicable, to adjust for a wide range of sampling periods (2.8-13.1 h). During the 4-h time periods, mean personal PM2.5 exposures were correlated with personal CO exposures during lunch (r = 0.67 p = 0.024 n = 11) and dinner (r = 0.72 p = 0.0011 n = 17) in all study households. Personal PM2.5 exposures and kitchen CO concentrations were also correlated during lunch (r = 0.76 p = 0.018 n = 9) and dinner (r = 0.60 p = 0.018 n = 15). CO may be a useful indicator of PM during 4-h time scales measured in real time, particularly during high woodsmoke exposures, particularly during residential biomass cooking.

Commodore, Adwoa A.; Hartinger, Stella M.; Lanata, Claudio F.; Mäusezahl, Daniel; Gil, Ana I.; Hall, Daniel B.; Aguilar-Villalobos, Manuel; Naeher, Luke P.

2013-11-01

131

Radiation exposure time during MBSS: influence of swallowing impairment severity, medical diagnosis, clinician experience, and standardized protocol use.  

PubMed

Guidelines and preventive measures have been established to limit radiation exposure time during modified barium swallow studies (MBSS) but multiple variables may influence the duration of the exam. This study examined the influence of clinician experience, medical diagnosis category, swallowing impairment severity, and use of a standardized protocol on fluoroscopy time. A retrospective review of 739 MBSSs performed on 612 patients (342 males/270 females; age range = 18-96 years) completed in 1 year at the Medical University of South Carolina was performed with IRB approval. All studies were completed by speech-language pathologists trained in the data collection protocol, interpretation, and scoring of the MBSImP™(©). Medical diagnosis category, swallowing impairment severity (MBSImP™(©) score), clinician experience, and fluoroscopy time were the variables recorded for analysis. Fluoroscopy time was not significantly associated with medical diagnosis category (p = 0.10). The severity of the MBSImP™(©) Oral Total and Pharyngeal Total resulted in statistically significant increases in fluoroscopy time (p < 0.05). Studies by novice clinicians had longer exposure times when compared to those of experienced clinicians (p = 0.037). Average radiation exposure time using the MBSImP™(©) approach was 2.9 min, with a 95 % confidence interval of 2.8-3.0 min, which was well within the range of exposure times reported in the literature. This study provides preliminary information regarding the impact of medical diagnosis category, swallowing impairment severity, and clinician experience on fluoroscopy time. These findings also suggest that a thorough, standardized protocol for MBSSs did not cause unnecessary radiation exposure time during the MBSS. PMID:22692431

Bonilha, Heather Shaw; Humphries, Kate; Blair, Julie; Hill, Elizabeth G; McGrattan, Katlyn; Carnes, Brittni; Huda, Walter; Martin-Harris, Bonnie

2013-03-01

132

Predicting personal exposure to airborne carbonyls using residential measurements and time/activity data  

NASA Astrophysics Data System (ADS)

As a part of the Relationships of Indoor, Outdoor, and Personal Air (RIOPA) study, 48 h integrated residential indoor, outdoor, and personal exposure concentrations of 10 carbonyls were simultaneously measured in 234 homes selected from three US cities using the Passive Aldehydes and Ketones Samplers (PAKS). In this paper, we examine the feasibility of using residential indoor concentrations to predict personal exposures to carbonyls. Based on paired t-tests, the means of indoor concentrations were not different from those of personal exposure concentrations for eight out of the 10 measured carbonyls, indicating indoor carbonyls concentrations, in general, well predicted the central tendency of personal exposure concentrations. In a linear regression model, indoor concentrations explained 47%, 55%, and 65% of personal exposure variance for formaldehyde, acetaldehyde, and hexaldehyde, respectively. The predictability of indoor concentrations on cross-individual variability in personal exposure for the other carbonyls was poorer, explaining<20% of variance for acetone, acrolein, crotonaldehyde, and glyoxal. A factor analysis, coupled with multiple linear regression analyses, was also performed to examine the impact of human activities on personal exposure concentrations. It was found that activities related to driving a vehicle and performing yard work had significant impacts on personal exposures to a few carbonyls.

Liu, Weili; Zhang, Junfeng (Jim); Korn, Leo R.; Zhang, Lin; Weisel, Clifford P.; Turpin, Barbara; Morandi, Maria; Stock, Tom; Colome, Steve

133

Application of MOSFET Detectors for Dosimetry in Small Animal Radiography Using Short Exposure Times  

PubMed Central

Digital subtraction angiography (DSA) X-ray imaging for small animals can be used for functional phenotyping given its ability to capture rapid physiological changes at high spatial and temporal resolution. The higher temporal and spatial requirements for small-animal imaging drive the need for short, high-flux X-ray pulses. However, high doses of ionizing radiation can affect the physiology. The purpose of this study was to verify and apply metal oxide semiconductor field effect transistor (MOSFET) technology to dosimetry for small-animal diagnostic imaging. A tungsten anode X-ray source was used to expose a tissue-equivalent mouse phantom. Dose measurements were made on the phantom surface and interior. The MOSFETs were verified with thermoluminescence dosimeters (TLDs). Bland-Altman analysis showed that the MOSFET results agreed with the TLD results (bias, 0.0625). Using typical small animal DSA scan parameters, the dose ranged from 0.7 to 2.2 cGy. Application of the MOSFETs in the small animal environment provided two main benefits: (1) the availability of results in near real-time instead of the hours needed for TLD processes and (2) the ability to support multiple exposures with different X-ray techniques (various of kVp, mA and ms) using the same MOSFET. This MOSFET technology has proven to be a fast, reliable small animal dosimetry method for DSA imaging and is a good system for dose monitoring for serial and gene expression studies.

De Lin, Ming; Toncheva, Greta; Nguyen, Giao; Kim, Sangroh; Anderson-Evans, Colin; Johnson, G. Allan; Yoshizumi, Terry T.

2008-01-01

134

Application of MOSFET detectors for dosimetry in small animal radiography using short exposure times.  

PubMed

Digital subtraction angiography (DSA) X-ray imaging for small animals can be used for functional phenotyping given its ability to capture rapid physiological changes at high spatial and temporal resolution. The higher temporal and spatial requirements for small-animal imaging drive the need for short, high-flux X-ray pulses. However, high doses of ionizing radiation can affect the physiology. The purpose of this study was to verify and apply metal oxide semiconductor field effect transistor (MOSFET) technology to dosimetry for small-animal diagnostic imaging. A tungsten anode X-ray source was used to expose a tissue-equivalent mouse phantom. Dose measurements were made on the phantom surface and interior. The MOSFETs were verified with thermoluminescence dosimeters (TLDs). Bland-Altman analysis showed that the MOSFET results agreed with the TLD results (bias, 0.0625). Using typical small animal DSA scan parameters, the dose ranged from 0.7 to 2.2 cGy. Application of the MOSFETs in the small animal environment provided two main benefits: (1) the availability of results in near real-time instead of the hours needed for TLD processes and (2) the ability to support multiple exposures with different X-ray techniques (various of kVp, mA and ms) using the same MOSFET. This MOSFET technology has proven to be a fast, reliable small animal dosimetry method for DSA imaging and is a good system for dose monitoring for serial and gene expression studies. PMID:18666818

De Lin, Ming; Toncheva, Greta; Nguyen, Giao; Kim, Sangroh; Anderson-Evans, Colin; Johnson, G Allan; Yoshizumi, Terry T

2008-08-01

135

Efficient space-time sampling with pixel-wise coded exposure for high-speed imaging.  

PubMed

Cameras face a fundamental trade-off between spatial and temporal resolution. Digital still cameras can capture images with high spatial resolution, but most high-speed video cameras have relatively low spatial resolution. It is hard to overcome this trade-off without incurring a significant increase in hardware costs. In this paper, we propose techniques for sampling, representing, and reconstructing the space-time volume to overcome this trade-off. Our approach has two important distinctions compared to previous works: 1) We achieve sparse representation of videos by learning an overcomplete dictionary on video patches, and 2) we adhere to practical hardware constraints on sampling schemes imposed by architectures of current image sensors, which means that our sampling function can be implemented on CMOS image sensors with modified control units in the future. We evaluate components of our approach, sampling function and sparse representation, by comparing them to several existing approaches. We also implement a prototype imaging system with pixel-wise coded exposure control using a liquid crystal on silicon device. System characteristics such as field of view and modulation transfer function are evaluated for our imaging system. Both simulations and experiments on a wide range of scenes show that our method can effectively reconstruct a video from a single coded image while maintaining high spatial resolution. PMID:24356347

Liu, Dengyu; Gu, Jinwei; Hitomi, Yasunobu; Gupta, Mohit; Mitsunaga, Tomoo; Nayar, Shree K

2014-02-01

136

Performance of a 512 x 512 gated CMOS imager with a 250 ps exposure time  

NASA Astrophysics Data System (ADS)

We describe the performance of a 512x512 gated CMOS read out integrated circuit (ROIC) with a 250 ps exposure time. A low-skew, H-tree trigger distribution system is used to locally generate individual pixel gates in each 8x8 neighborhood of the ROIC. The temporal width of the gate is voltage controlled and user selectable via a precision potentiometer. The gating implementation was first validated in optical tests of a 64x64 pixel prototype ROIC developed as a proof-of-concept during the early phases of the development program. The layout of the H-Tree addresses each quadrant of the ROIC independently and admits operation of the ROIC in two modes. If "common mode" triggering is used, the camera provides a single 512x512 image. If independent triggers are used, the camera can provide up to four 256x256 images with a frame separation set by the trigger intervals. The ROIC design includes small (sub-pixel) optical photodiode structures to allow test and characterization of the ROIC using optical sources prior to bump bonding. Reported test results were obtained using short pulse, second harmonic Ti:Sapphire laser systems operating at ?~ 400 nm at sub-ps pulse widths.

Teruya, Alan T.; Vernon, Stephen P.; Moody, James D.; Hsing, Warren W.; Brown, Christopher G.; Griffin, Matthew; Mead, Andrew S.; Tran, Vu

2012-10-01

137

High-time resolution and size-segregated elemental composition in high-intensity pyrotechnic exposures.  

PubMed

Typical of festivals in Eastern Spain, mascletàs are high-intensity pyrotechnic events where thousands of firecrackers are burnt in an intense, rapid episode that generates short-lived heavy aerosol clouds. High temporal resolution and size distribution characterisation of aerosol components were performed to evaluate the effects of the brief (<30 min) and acute exposure on the spectators present. Very high concentrations of firework specific elements, especially in the fine fraction, were reached during mascletàs, with values of about 500 ?g/m(3) for K and 300 ?g/m(3) for Cl. Sr, Al, Mg, Ba, Cu, Co, Zn, and Pb concentration increase factors of more than 100 (1000 for Sr and Ba) were observed in the fine fraction with respect to background levels. Crustal origin elements, like Ca, Fe, Si, Ti, also showed an important concentration rise (~10 times above background levels) but this is due to dust resuspension by pyrotechnic explosions. The crustal components are mainly in the coarse mode (>90% elemental mass), between 2 and 3 ?m. Most firework related metals are concentrated in the submicrometric region (>80%) with a trimodal size distribution. This may be interesting to epidemiologists given the toxic effects that such fine, metal-rich particles can have on human health. PMID:23026448

Crespo, Javier; Yubero, Eduardo; Nicolás, Jose F; Lucarelli, Franco; Nava, Silvia; Chiari, Massimo; Calzolai, Giulia

2012-11-30

138

Improvement of attention span and reaction time with hyperbaric oxygen treatment in patients with toxic injury due to mold exposure  

Microsoft Academic Search

It is, by now, well established that mold toxins (mycotoxins) can cause significant adverse health effects. In this study,\\u000a 15 subjects who developed an attention deficit disorder (ADD) and slowing of reaction time at the time of exposure to mold\\u000a toxins were identified. Deficits in attention span and reaction time were documented not only by taking a careful history,\\u000a but

N. Ezra; K. Dang; G. Heuser

2011-01-01

139

Exposure Time to Lethal Temperatures for Meloidogyne incognita Suppression and Its Implication for Soil Solarization.  

PubMed

Meloidogyne incognita eggs or J2 were incubated in test tubes containing sand:peat mix and immersed in a water bath heated to 38, 39, 40, 41, 42, 43, 44 and 45 degrees C for a series of time intervals. Controls were maintained at 22 degrees C. Nematodes surviving or hatching were collected from Baermann trays after three weeks of incubation. Regression analyses between percent survival or egg hatch and hours of heat treatment were performed for each temperature. Complete suppression of egg hatch required 389.8, 164.5, 32.9, 19.7 and 13.1 hours at 38, 39, 40, 41 and 42 degrees C, respectively. Complete killing of J2 required 47.9, 46.2, 17.5 and 13.8 hours at 39, 40, 41 and 42 degrees C, respectively. J2 were not completely killed at 38 degrees C within 40 hours of treatment, but were killed within one hour at 44 and 45 degrees C. Effect of temperature on nematode killing is not determined by heat units. Oscillating temperature between cool and warm did not interfere with the nematode suppressive effect by the heat treatment. Six-week solarization in the field during the summers of 2003 and 2004 in Florida accumulated heat exposure times in the top 15 cm of soil that surpassed levels required to kill M. incognita as determined in the water bath experiments. Although near zero M. incognita were detected right after solarization, the nematode population densities increased after a cycle of a susceptible pepper crop. Therefore, future research should address failure of solarization to kill nematodes in the deeper soil layers. PMID:19259512

Wang, K-H; McSorley, R

2008-03-01

140

Time Course of Gene Expression of Inflammatory Mediators in Rat Lung after Diesel Exhaust Particle Exposure  

PubMed Central

Diesel exhaust particles (DEPs) at three concentrations (5, 35, and 50 mg/kg body weight) were instilled into rats intratracheally. We studied gene expression at 1, 7, and 30 days postexposure in cells obtained by bronchoalveolar lavage (BAL) and in lung tissue. Using real-time reverse transcriptase-polymerase chain reaction (RT-PCR), we measured the mRNA levels of eight genes [interleukin (IL)-1?, IL-6, IL-10, iNOS (inducible nitric oxide synthase), MCP-1 (monocyte chemoattractant protein-1), MIP-2 (macrophage inflammatory protein-2), TGF-?1 (transforming growth factor-?1), and TNF-? (tumor necrosis factor-?)] in BAL cells and four genes [IL-6, ICAM-1 (intercellular adhesion molecule-1), GM-CSF (granulocyte/macrophage-colony stimulating factor), and RANTES (regulated upon activation normal T cell expressed and secreted)] in lung tissue. In BAL cells on day 1, high-dose exposure induced a significant up-regulation of IL-1?, iNOS, MCP-1, and MIP-2 but no change in IL-6, IL-10, TGF-?1, and TNF-? mRNA levels. There was no change in the mRNA levels of IL-6, RANTES, ICAM-1, and GM-CSF in lung tissue. Nitric oxide production and levels of MCP-1 and MIP-2 were increased in the 24-hr culture media of alveolar macrophages (AMs) obtained on day 1. IL-6, MCP-1, and MIP-2 levels were also elevated in the BAL fluid. BAL fluid also showed increases in albumin and lactate dehydrogenase. The cellular content in BAL fluid increased at all doses and at all time periods, mainly due to an increase in polymorphonuclear leukocytes. In vitro studies in AMs and cultured lung fibroblasts showed that lung fibroblasts are a significant source of IL-6 and MCP-1 in the lung.

Rao, K. Murali Krishna; Ma, Jane Y. C.; Meighan, Terence; Barger, Mark W.; Pack, Donna; Vallyathan, Val

2005-01-01

141

Dependence on sampling rates of Radiello((R)) diffusion sampler for BTEX measurements with the concentration level and exposure time.  

PubMed

Radiello((R)) diffusive samplers filled with a thermally desorbable adsorbent (graphitised charcoal Carbograph 4) have been tested for the monitoring of BTEX. The sampling rates have been estimated under various controlled atmospheres in order to evaluate the effects of two factors (exposure time, concentration levels and their interaction) on the performances of the Radiello((R)) sampler. Experiments have been carried out under various atmospheres in exposure chamber. A total of 174 Radiello((R)) samplers were exposed while varying two conditions: exposure time (1, 3, 7 and 14 days) and BTEX concentrations (low, medium and high levels). The results show that the sampling rates of benzene and toluene decrease for exposure of 14 days and especially for high concentration levels: decrease of 30% at 10mugm(-3) for benzene and 14% at 30mugm(-3) for toluene. To try to explain the variations of these sampling rates, the breakthrough volumes (V(B)) of BTEX on Carbograph 4 have been determined at different temperature and concentration conditions in order to evaluate the Langmuir parameters and their adsorption enthalpy (-DeltaH(ads)) using the Van't Hoff equation. With regard to these adsorption characteristics, the dependence of sampling rates with concentration level and exposure time were analysed and discussed. PMID:18969937

Pennequin-Cardinal, Anne; Plaisance, Hervé; Locoge, Nadine; Ramalho, Olivier; Kirchner, Séverine; Galloo, Jean-Claude

2005-03-15

142

Specific time of exposure during tadpole development influences biological effects of the insecticide carbaryl in green frogs (Lithobates clamitans).  

PubMed

The orchestration of anuran metamorphosis is initiated and integrated by thyroid hormones, which change dynamically during larval development and which may represent a target of disruption by environmental contaminants. Studies have found that some anurans experience increased rates of development when exposed to the insecticide carbaryl later in larval development, suggesting that this insecticide could affect thyroid hormone-associated biological pathways. However, the time in development when tadpoles are sensitive to insecticide exposure has not been clearly defined nor has the mechanism been tested. In two separate studies, we exposed recently hatched green frog (Lithobates clamitans) tadpoles to a single, three day carbaryl exposure in the laboratory at either 2, 4, 8, or 16 weeks post-hatching. We examined the impact of carbaryl exposure on mRNA abundance patterns in the brains of frogs following metamorphosis months after a single three day exposure (experiment 1) and in tadpole tails three days after exposure (experiment 2) using cDNA microarrays and quantitative real time polymerase chain reaction (QPCR) analyses. For tadpoles reared through metamorphosis, we measured tadpole growth and development, as well as time to, mass at, and survival to metamorphosis. Although carbaryl did not significantly impact tadpole development, metamorphosis, or survival, clear exposure-related alterations in both tail and brain transcript levels were evident when tadpoles were exposed to carbaryl, particularly in tadpoles exposed at weeks 8 and 16 post-hatching, indicating both short-term and long-term alterations in mRNA expression. These results indicate that carbaryl can have long-lasting effects on brain development when exposure occurs at sensitive developmental stages, which may have implications for animal fitness and function later in the life cycle. PMID:23399446

Boone, Michelle D; Hammond, S Austin; Veldhoen, Nik; Youngquist, Melissa; Helbing, Caren C

2013-04-15

143

Personal exposure to carcinogenic and toxic air pollutants in Stockholm, Sweden: A comparison over time  

NASA Astrophysics Data System (ADS)

Benzene, 1,3-butadiene, benz(a)pyrene, NO x and NO 2 were measured by personal sampling, stationary indoor sampling, and at two reference sites (urban background/traffic site) in Stockholm, Sweden during September-December 2009. The aim was to investigate whether the air pollution levels had decreased since a previous study conducted six year earlier, and to compare personal exposure levels (one-week average) and indoor levels with levels at outdoor reference sites. Participants were 20-50 years of age, randomly selected among residents in the Stockholm municipality. The personal exposure levels to benzene and 1,3-butadiene were higher than the levels at the reference sites. Personal exposure to NO x and NO 2 were higher than urban background levels, but the NO 2 exposure level was lower than traffic site levels. Benz(a)pyrene showed lower concentrations indoors compared to outdoor levels, although a significant correlation was found between indoor and outdoor levels. All of the air pollutant levels had decreased since the previous study, both for personal exposure and reference site levels. The results from the present study indicate that urban background measurements for these compounds are suitable for monitoring decreasing or increasing trends in air pollution levels but since the personal exposure levels did not correlate well with weekly ambient levels, personal sampling seems essential for assessing population exposure.

Yazar, Mine; Bellander, Tom; Merritt, Anne-Sophie

2011-06-01

144

Assessment of time to pregnancy and spontaneous abortion status following occupational exposure to organic solvents mixture  

Microsoft Academic Search

Purpose  Due to increasing usage of chemicals in various industries, occupational exposure of women with these materials is unavoidable.\\u000a Nowadays, some studies indicate adverse effects of exposure to these chemicals, especially organic solvents on the reproductive\\u000a system of females. This study aimed to assess the relationship between spontaneous abortion and occupational exposure to organic\\u000a solvents mixture in pharmaceutical industry.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  This study

Mir Saeed Attarchi; Monir Ashouri; Yasser Labbafinejad; Saber Mohammadi

145

Advancing Environmental Noise Pollution Analysis in Urban Areas by Considering the Variation of Population Exposure in Space and Time  

NASA Astrophysics Data System (ADS)

Ambient noise is a subtle form of pollution in large urban areas, degrading human health and well-being. In Europe, directives require that urban environmental noise be measured and mapped for the main periods of the daily cycle. Subsequent analyses of human exposure to noise in those periods is usually conducted using resident (i.e., nighttime) population from the census and assuming constant densities within the enumeration units. However, population distribution and densities vary considerably from night to day in metropolitan areas, and disregard for that process results in gross misestimation of exposure to ambient noise in the daytime period. This study considers the spatio-temporal variation of population distribution in assessing exposure to ambient noise in a major urban area, the city of Lisbon, Portugal. Detailed and compatible day- and nighttime population distribution maps were used, developed by means of "intelligent dasymetric mapping". After categorizing noise levels in existing maps in each period, classified according to current legislation, human exposure to ambient noise was assessed with temporally matching population surfaces. Population exposure to noise in 2000 and 2009 was compared and further analyzed in regards to main source of noise, i.e. road traffic vs. aircraft.. Results show that human exposure to noise shifts substantially in time and space, with a significant increase in exposed population from the nighttime to daytime period, especially in the higher noise levels. This is due to the combined effects of the daily variation of noise patterns and population distribution.

Freire, S.; Gomes, N.

2013-05-01

146

BLOOD AND BRAIN CONCENTRATIONS OF BIFENTHRIN CORRELATE WITH DECREASED MOTOR ACTIVITY INDEPENDENT OF TIME OF EXPOSURE  

EPA Science Inventory

Pyrethroids are neurotoxic insecticides used in a variety of agricultural and household activities. Due to the phase-out of organophosphate pesticides, the use of pyrethroids has increased. The potential for human exposure to pyrethroids has prompted pharmacodynamic and pharmac...

147

Pregnancy blockage following multiple-male copulation or exposure at the time of mating in deer mice, Peromyscus maniculatus  

Microsoft Academic Search

Pregnancy blockage resulting from multiple-male copulation or exposure around the time of mating was studied in three experiments on deer mice, Peromyscus maniculatus. First, significantly more females were pregnant after copulating, either with or without disturbance and a delay, with one male than after receiving the same total number of ejaculations from two males. Second, when females received three ejaculations

Donald A. Dewsbury

1982-01-01

148

Influence of calcium oxide level and time of exposure to sugarcane on in vitro and in situ digestive kinetics  

Microsoft Academic Search

These experiments were carried out to evaluate, using in vitro and in situ techniques, the effects of three inclusion levels of calcium oxide (0, 5, and 10g\\/kg of sugarcane fresh matter) and four exposure times (0, 24, 48, and 72h) of sugarcane to calcium oxide on the chemical composition and digestive kinetic parameters of sugarcane. The treatments were arranged in

D. S. Pina; L. O. Tedeschi; S. C. Valadares Filho; J. A. G. Azevedo; E. Detmann; R. Anderson

2009-01-01

149

Evaluation of Real-Time Techniques to Measure Hydrogen Peroxide in Air at the Permissible Exposure Limit  

Microsoft Academic Search

The major occupational concern from bio-decontamination of equipment using vapor phase hydrogen peroxide (VHP) generation systems is potential operator exposure outside the protective barrier from possible VHP leaks or accidental releases from the sealed piece of equipment during decontamination. For this reason, different real-time monitoring techniques were evaluated to determine their ability to accurately measure VHP at concentrations ranging from

Mark A. Puskar; Marcia R. Plese

1996-01-01

150

Early life exposures and the occurrence and timing of heart disease among the older adult Puerto Rican population.  

PubMed

Few studies have examined the effects of early life conditions on the timing of the onset of heart disease. We use the remarkable example of a representative sample of the population of older Puerto Ricans aged 60-74 who lived in the countryside during childhood (n = 1,438) to examine the effects ofseasonal exposures to poor nutrition and infectious diseases during late gestation on the timing of the onset and the probability of ever experiencing adult heart disease. Cox and log logistic hazard models controlling for childhood conditions (self-reported childhood health status and socioeconomic status [SES], rheumatic fever, and knee height) and adult risk factors (adult SES, obesity, smoking, exercise, and self-reported diabetes) showed that the risk of onset of heart disease was 65% higher among those born during high-exposure periods compared with unexposed individuals. However, there were no significant differences in median time of onset for those ever experiencing heart disease. As a comparison, we found that there were no significant seasonality effects for those who lived in urban areas during childhood. We conclude that early exposures in utero have important ramifications for adult heart disease among the older Puerto Rican population. We show, however, that while exposure is associated with the probability of ever experiencing adult heart disease, it is not associated with the timing of onset among those who do experience it. PMID:20355682

McEnry, Mry; Palloni, Alberto

2010-02-01

151

TIME-DEPENDENT EFFECTS ON GENE EXPRESSION IN RAT SEMINAL VESICLE DEVELOPMENTALLY ALTERED BY IN UTERO EXPOSURE TO TCDD  

EPA Science Inventory

TIME-DEPENDENT EFFECTS ON GENE EXPRESSION IN RAT SEMINAL VESICLE DEVELOPMENTALLY ALTERED BY IN UTERO EXPOSURE TO TCDD. V M Richardson', J T Hamm2, and L S Birnbaum1. 'USEPA, ORD/NHEERL/ETD, Research Triangle Park, NC, USA, 'Curriculum in Toxicology, University of North Carolina, ...

152

The Effect of Mode of Instruction and Exposure Time to Examples on the Acquisition of a Biological Concept.  

ERIC Educational Resources Information Center

The purpose of this study was to determine which mode of instruction (deductive or inductive) and which time of exposure produced greatest student acquisition of a classificational concept. The population consisted of 385 high school students randomly assigned to classes at the beginning of the school year; subsequently, 21 classes were randomly…

Koran, John J., Jr.; And Others

153

The Timing of Prenatal Exposure to Maternal Cortisol and Psychosocial Stress Is Associated with Human Infant Cognitive Development  

ERIC Educational Resources Information Center

The consequences of prenatal maternal stress for development were examined in 125 full-term infants at 3, 6, and 12 months of age. Maternal cortisol and psychological state were evaluated 5 times during pregnancy. Exposure to elevated concentrations of cortisol early in gestation was associated with a slower rate of development over the 1st year…

Davis, Elysia P.; Sandman, Curt A.

2010-01-01

154

Development of the town data base: Estimates of exposure rates and times of fallout arrival near the Nevada Test Site  

SciTech Connect

As part of the U.S. Department of Energy`s Off-Site Radiation Exposure Review Project, the time of fallout arrival and the H+12 exposure rate were estimated for populated locations in Arizona, California, Nevada, and Utah that were affected by fallout from one or more nuclear tests at the Nevada Test Site. Estimates of exposure rate were derived from measured values recorded before and after each test by fallout monitors in the field. The estimate for a given location was obtained by retrieving from a data base all measurements made in the vicinity, decay-correcting them to H+12, and calculating an average. Estimates were also derived from maps produced after most events that show isopleths of exposure rate and time of fallout arrival. Both sets of isopleths on these maps were digitized, and kriging was used to interpolate values at the nodes of a 10-km grid covering the pattern. The values at any location within the grid were then estimated from the values at the surrounding grid nodes. Estimates of dispersion (standard deviation) were also calculated. The Town Data Base contains the estimates for all combinations of location and nuclear event for which the estimated mean H+12 exposure rate was greater than three times background. A listing of the data base is included as an appendix. The information was used by other project task groups to estimate the radiation dose that off-site populations and individuals may have received as a result of exposure to fallout from Nevada nuclear tests.

Thompson, C.B.; McArthur, R.D. [Univ. and Community College System of Nevada, Las Vegas, NV (United States); Hutchinson, S.W. [Mead Johnson Nutritional Group, Evansville, IN (United States)

1994-09-01

155

Evaluation of quantitative real-time PCR for rapid assessments of the exposure of sentinel fish to Myxobolus cerebralis  

Microsoft Academic Search

Pathogen-free rainbow trout (Oncorhynchus mykiss) aged 735 degree days were experimentally exposed to a low dose of infectious Myxobolus cerebralis (20 triactinomyxons fish?1). Three time periods were chosen for sampling that included 10 days (d), 67 d, and 5 months (mo) post exposure. Five diagnostic assays were used: (1) conventional single-round polymerase chain reaction (PCR), (2) nested PCR, (3) real-time TaqMan PCR, (4)

Garry O. Kelley; Mark A. Adkison; Francisco J. Zagmutt-Vergara; Christian M. Leutenegger; Jeffery W. Bethel; Karin A. Myklebust; Terry S. McDowell; Ronald P. Hedrick

2006-01-01

156

Effect of prolonged isothermal exposure on elevated-temperature, time-dependent fatigue-crack propagation in INCONEL alloy 783  

Microsoft Academic Search

The effect of isothermal exposure on the elevated-temperature, time-dependent fatigue-crack propagation (FCP) in INCONEL Alloy 783 is investigated. Commercially produced Alloy 783 was annealed and aged following the standard heat-treatment procedure. One set of specimens was then isothermally exposed at 500 °C for 3000 hours. All specimens were subjected to FCP tests with various hold-time periods and sustained-loading crack-growth tests

Longzhou Ma; Keh-Minn Chang; Sarwan K. Mannan; Shailesh J. Patel

2002-01-01

157

Changes in the timing of reproduction following chronic exposure to ibuprofen in Japanese medaka, Oryzias latipes.  

PubMed

Effluents from wastewater treatment plants and untreated sewage constitute a low concentration but continuous source of pharmaceutical products to the aquatic environment. One such drug, ibuprofen, is a non-steroidal anti-inflammatory agent that primarily acts through inhibition of cyclooxygenase (COX) activity. Oryzias latipes (Japanese medaka) were exposed for 6 weeks via water to three concentrations of ibuprofen (1-100 microg/L nominal concentrations) and a water control. Reproductive parameters, including frequency of spawning, fecundity, egg size, and rate of fertilization, were measured for each pair of adult medaka following 6 weeks of exposure. Livers homogenates from exposed individuals were assayed for COX activity and whole individuals were histologically examined for tissue damage. Increasing exposure to ibuprofen significantly increased the number of eggs per reproductive event, but decreased the number of spawning events per week. Liver tissue collected from females had less variability in COX activity with increasing concentration of ibuprofen exposure, and tended to have elevated hepatosomatic indices. No pathological damage was evident the in the gills, livers and head kidneys of animals from the highest exposure group. The results of this experiment begin to show that exposure to chronic low levels of ibuprofen alter the pattern of reproduction and may produce sex-specific responses in teleosts. PMID:17166604

Flippin, Jennifer L; Huggett, Duane; Foran, Christy M

2007-02-15

158

The Impact of Timing of Exposure to Violence on Violent Behavior in a High Poverty Sample of Inner City African American Youth  

Microsoft Academic Search

A growing body of research has linked exposure to violence to violent behavior, but few studies have examined the impact of the timing of exposure to violence on violent behavior among inner city, minority youth. Theoretical insights derived from developmental psychology and psychopathology (DPP) and Agnew’s general strain theory (GST) give contrasting accounts of whether exposure to violence has a

Richard Spano; Craig Rivera; John Bolland

2006-01-01

159

Double short-time exposure to pirarubicin produces higher cytotoxicity against T24 bladder cancer cells.  

PubMed

This study was designed to determine the ideal manner (schedule and duration) of intravesical chemotherapy using pirarubicin (THP). At first, T-24 cancer cells were treated with 50, 100, 150, and 200 ?g/ml THP for 10, 30 and 60 min. Following the first exposure, at various intervals (3, 6, 12, and 24 h), a second exposure to THP was performed under the same condition in vitro. The cell viability was measured by XTT assay. Further, the cells were scanned with a laser scanning cytometer (LSC) and DNA histograms were analyzed to evaluate the cell-cycle components. A single exposure of T-24 cells to THP resulted in significantly higher inhibition of cell growth for 30 min with 100 ?g/ml and higher concentrations of THP; for example, the cell viability was reduced to 15, 2, and 0% by incubating cells with 100, 150, and 200 ?g/ml of THP, respectively, whereas it was 49% with 50 ?g/ml THP. Double exposure of T-24 cells to THP resulted in significantly higher inhibition of cell growth than single treatment at all intervals. LSC assay demonstrated a higher sub-G(1) peak after double treatment with THP when compared with that after a single treatment. Similar cytotoxic effects following double treatment with THP were observed on other bladder cancer cell lines (UMUC3, TCCSUP, 5637, and 253J cells) in vitro. In conclusion, the double short-term exposure to bladder cancer cells by THP has more remarkable cytotoxic effects than the single exposure in vitro. PMID:20632198

Maruyama, Takuo; Higuchi, Yoshihide; Suzuki, Toru; Qiu, Jun; Yamamoto, Shingo; Shima, Hiroki

2011-02-01

160

Reduced exercise time in competitive simulations consequent to low level ozone exposure  

SciTech Connect

Ten highly trained endurance athletes were studied to determine the effects of exposure to low ozone (O/sub 3/) concentrations on simulated competitive endurance performance and associated physiological and subjective symptom responses. Each subject was randomly exposed to filtered air (FA), and to 0.12, 0.18, and 0.24 ppm O/sub 3/ while performing a 1 h competitive simulation protocol on a bicycle ergometer. Endurance performance was evaluated by the number of subjects unable to complete rides (last 30 min at an intense work load of approximately 86% VO/sub 2/max). All subjects completed the FA exposure, whereas one, five, and seven subjects did not complete the 0.12, 0.18, and 0.24 ppm O/sub 3/ exposures, respectively. Statistical analysis indicated a significant (P less than 0.05) increase in the inability of subjects to complete the competitive simulations with increasing O/sub 3/ concentration, including a significant difference between the 0.24 ppm O/sub 3/ and FA exposure. Significant decreases (P less than 0.05) were also observed following the 0.18 and 0.24 ppm O/sub 3/ exposures, respectively, in forced vital capacity (-7.8 and -9.9%), and forced expiratory volume in 1 s (-5.8 and -10.5%). No significant O/sub 3/ effect was observed for exercise respiratory metabolism or ventilatory pattern responses. However, the number of reported subjective symptoms increased significantly following the 0.18 and 0.24 ppm O/sub 3/ protocols. These data demonstrate significant decrements in simulated competitive endurance performance and in pulmonary function, with accompanying enhanced subjective symptoms, following exposure to low O/sub 3/ levels commonly observed in numerous metropolitan environments during the summer months.

Schelegle, E.S.; Adams, W.C.

1986-08-01

161

The impact of the developmental timing of trauma exposure on PTSD symptoms and psychosocial functioning among older adults.  

PubMed

The present study examined the impact of the developmental timing of trauma exposure on posttraumatic stress disorder (PTSD) symptoms and psychosocial functioning in a large sample of community-dwelling older adults (N = 1,995). Specifically, we investigated whether the negative consequences of exposure to traumatic events were greater for traumas experienced during childhood, adolescence, young adulthood, midlife, or older adulthood. Each of these developmental periods is characterized by age-related changes in cognitive and social processes that may influence psychological adjustment following trauma exposure. Results revealed that older adults who experienced their currently most distressing traumatic event during childhood exhibited more severe symptoms of PTSD and lower subjective happiness compared with older adults who experienced their most distressing trauma after the transition to adulthood. Similar findings emerged for measures of social support and coping ability. The differential effects of childhood compared with later life traumas were not fully explained by differences in cumulative trauma exposure or by differences in the objective and subjective characteristics of the events. Our findings demonstrate the enduring nature of traumatic events encountered early in the life course and underscore the importance of examining the developmental context of trauma exposure in investigations of the long-term consequences of traumatic experiences. PMID:23458662

Ogle, Christin M; Rubin, David C; Siegler, Ilene C

2013-11-01

162

Survival time analysis of least killifish (Heterandria formosa) and mosquitofish (Gambusia affinis) in acute exposures to endosulfan sulfate.  

PubMed

Single-species flow-through toxicity tests were conducted to determine the times-to-death of two indigenous fish to South Florida--least killifish (Heterandria formosa) and mosquitofish (Gambusia affinis)--from acute exposure to endosulfan sulfate. Mortalities were recorded within 8-h periods from test initiation to termination at 96 h. The 96-h LC(50)s for least killifish and mosquitofish estimated using the trimmed-Spearman-Karber method were 2.0 and 2.3 microg/l, respectively. An accelerated failure time model was used to estimate times to death at selected concentrations. Data were fit to log-normal, log-logistic, and Weibull distributions. Acute toxicity data fit to the Weibull distribution produced a better relative fit than log-normal or log-logistic distributions for both toxicity tests. The survival-time profiles and associated statistics illustrate the benefit of considering exposure duration as well as concentration when predicting acute risk to species' populations. Both toxicity tests had similar outcomes from exposure to endosulfan sulfate, with least killifish being slightly more likely to die at lower concentrations and shorter time periods than mosquitofish. From the models generated by the toxicity tests, times-to-death for least killifish and mosquitofish were estimated for environmentally relevant concentrations of total endosulfan at a site of concern in South Florida. When the results from the current toxicity tests were compared to environmental concentrations from previous screening-level ecological risk assessments, the durations necessary to potentially kill 10% or more of the populations of the two native south Florida fish species were estimated to be 77 and 96 h for least killifish and mosquitofish, respectively. However, the exposure values included the alpha and beta isomers as well as endosulfan sulfate; therefore, an understanding of their toxicity might be important in understanding the survival dynamics of fish species in endosulfan sulfate-contaminated sites. PMID:19921326

Carriger, John F; Hoang, Tham C; Rand, Gary M

2010-05-01

163

Modelling the increase of contrast sensitivity with grating area and exposure time  

Microsoft Academic Search

We extended the contrast detection model of human vision to temporal integration by taking into account the effect of exposure duration on contrast sensitivity for stationary gratings. The extended model thus comprised: (i) low-pass filtering due to the optical modulation transfer function of the eye; (ii) high-pass filtering (lateral inhibition) due to the neural modulation transfer function of the visual

Olavi Luntinen; Jyrki Rovamo; Risto Näsänen

1995-01-01

164

Age-time patterns of cancer to be anticipated from exposure to general mutagens.  

PubMed

We explore some stochastic considerations regarding accumulation of mutations in relation to carcinogenesis. In particular, we consider the effect of exposure to specific agents, especially ionizing radiation, that may increase mutation rates. The formulation and consequences are a further development of the Armitage-Doll model; both in terms of background cancer where assumptions are substantially weakened, and in terms of the effect of specific mutagenic exposures through generally increasing mutation rates. Under our model the effect of exposure is equivalent to a change in age scale, adding to age a parametric multiple of cumulative dose to the mutagen, which leads to useful formulae for the relative risk. In particular, the excess relative risk at age a behaves approximately as a parametric multiple of the mean dose over ages prior to a. These results do not require assuming that some fixed number of mutations are required for malignancy. The implications are particularly useful in providing guidance for descriptive analyses since they have characteristics largely independent of parameter values. It is indicated that the model consequences conform remarkably well to observations from cohort studies of the A-bomb survivors, miners with prolonged exposure to radon, and cigarette smokers who stopped smoking at various ages. PMID:12925519

Pierce, Donald A; Vaeth, Michael

2003-04-01

165

Effects of Repeated Sublethal VX Exposure on Operant Time Estimation in Rats.  

National Technical Information Service (NTIS)

Thirty-two rats were trained to stability under a differential- reinforcement-of-low rates 20-s schedule with a sucrose pellet as the reinforcer and a lever press as the operant response. The exposure groups were saline, 0.3, 0.4, and 0.5LD50 VX delivered...

D. W. Kahler J. C. LaMont L. A. Lumley T. M. Myers

2007-01-01

166

“Estimating Regional Background Air Quality using Space/Time Ordinary Kriging to Support Exposure Studies”  

EPA Science Inventory

Local-scale dispersion models are increasingly being used to perform exposure assessments. These types of models, while able to characterize local-scale air quality at increasing spatial scale, however, lack the ability to include background concentration in their overall estimat...

167

Predictors of fluoroscopy time and estimated radiation exposure during radiofrequency catheter ablation procedures  

Microsoft Academic Search

The objective of this study was to identify factors that predict fluoroscopy duration and radiation exposure during catheter ablation procedures. The patient population included 859 patients who participated in the Atakr Ablation System clinical trial at 1 of 9 centers (398 male and 461 female patients, aged 36 ± 21 years). Each patient underwent catheter ablation of an accessory pathway,

Lawrence S. Rosenthal; Mahadevappa Mahesh; Thomas J. Beck; J. Phillip Saul; John M. Miller; Neal Kay; Lawrence S. Klein; Stephen Huang; Paul Gillette; Eric Prystowsky; Mark Carlson; Ronald D. Berger; John H. Lawrence; Patrick Yong; Hugh Calkins

1998-01-01

168

Do Time in Child Care and Peer Group Exposure Predict Poor Socioemotional Adjustment in Norway?  

ERIC Educational Resources Information Center

Extensive exposure to nonparental child care during the first 4.5 years of life has been demonstrated in some American studies to negatively affect children's socioemotional functioning. Data from 935 preschool children who averaged 54.9 (SD = 3.0) months of age, from Trondheim, Norway were used to examine whether such negative effects, would…

Solheim, Elisabet; Wichstrøm, Lars; Belsky, Jay; Berg-Nielsen, Turid Suzanne

2013-01-01

169

Pubertal timing after neonatal diethylstilbestrol exposure in female rats: neuroendocrine vs peripheral effects and additive role of prenatal food restriction.  

PubMed

We studied the effects of neonatal exposure to diethylstilbestrol (DES) on pubertal timing in female rats. We examined associated neuroendocrine changes and effects of prenatal food restriction. Age at vaginal opening was advanced after exposure to 10 ?g/kg/d of DES and delayed after 1 ?g/kg/d (subcutaneous injections). Using this lower dose, pulsatile GnRH secretion was slower at 25 days of age. Both doses reduced KiSS1 mRNA levels at 15 days of age. Using functional Kisspeptin promoter assay, 1 or 10 ?M DES reduced or increased KISS1 transcription, respectively. Leptin stimulatory effect on GnRH secretion in vitro (15 days of age) was reduced after prenatal food restriction and neonatal DES exposure (higher dose), both effects being cumulative. Thus, alterations in pubertal timing by DES neonatally are not unequivocally toward precocity, the level of exposure being critical. We provide evidence of neuroendocrine disruption and interaction with prenatal food availability. PMID:24316331

Franssen, Delphine; Ioannou, Yiannis S; Alvarez-real, Alexandra; Gerard, Arlette; Mueller, Johanna K; Heger, Sabine; Bourguignon, Jean-Pierre; Parent, Anne-Simone

2014-04-01

170

The effect of time of exposure to elevated temperatures on the flammability limits of some common gaseous fuels in air  

SciTech Connect

The flammability limits of methane, ethylene, propane, and hydrogen were experimentally determined at elevated initial mixture temperatures up to 350 C at atmospheric pressure for upward flame propagation in a steel test tube apparatus. The existence of preignition reactions at these levels of temperatures that may influence the value of the flammability limits was also investigated. The fuel-air mixtures were exposed to elevated temperatures over different periods of time before spark ignition (up to 2 h). It was shown that the flammability limits for methane widened approximately linearly with an increase in the initial mixture temperature over the entire range of temperatures tested and were not affected by the length of the exposure time to these temperatures before spark ignition. However, different behavior was observed for the flammability limits of the other tested fuels--ethylene, propane, and hydrogen. At higher temperatures the flammability limits narrowed and were very significantly affected by the exposure time. The longer was the exposure time of fuel-air mixtures to the elevated temperatures, the narrower were their flammability limits.

Wierzba, I.; Ale, B.B. [Univ. of Calgary, Alberta (Canada). Dept. of Mechanical Engineering

1999-01-01

171

Large-Scale Analysis of Acute Ethanol Exposure in Zebrafish Development: A Critical Time Window and Resilience  

PubMed Central

Background In humans, ethanol exposure during pregnancy causes a spectrum of developmental defects (fetal alcohol syndrome or FAS). Individuals vary in phenotypic expression. Zebrafish embryos develop FAS-like features after ethanol exposure. In this study, we ask whether stage-specific effects of ethanol can be identified in the zebrafish, and if so, whether they allow the pinpointing of sensitive developmental mechanisms. We have therefore conducted the first large-scale (>1500 embryos) analysis of acute, stage-specific drug effects on zebrafish development, with a large panel of readouts. Methodology/Principal Findings Zebrafish embryos were raised in 96-well plates. Range-finding indicated that 10% ethanol for 1 h was suitable for an acute exposure regime. High-resolution magic-angle spinning proton magnetic resonance spectroscopy showed that this produced a transient pulse of 0.86% concentration of ethanol in the embryo within the chorion. Survivors at 5 days postfertilisation were analysed. Phenotypes ranged from normal (resilient) to severely malformed. Ethanol exposure at early stages caused high mortality (?88%). At later stages of exposure, mortality declined and malformations developed. Pharyngeal arch hypoplasia and behavioral impairment were most common after prim-6 and prim-16 exposure. By contrast, microphthalmia and growth retardation were stage-independent. Conclusions Our findings show that some ethanol effects are strongly stage-dependent. The phenotypes mimic key aspects of FAS including craniofacial abnormality, microphthalmia, growth retardation and behavioral impairment. We also identify a critical time window (prim-6 and prim-16) for ethanol sensitivity. Finally, our identification of a wide phenotypic spectrum is reminiscent of human FAS, and may provide a useful model for studying disease resilience.

Ali, Shaukat; Champagne, Danielle L.; Alia, Alia; Richardson, Michael K.

2011-01-01

172

The synergism between bovine papillomavirus type 4 and quercetin is dependent on the timing of exposure.  

PubMed

Exposure to the flavonoid quercetin and transfection with bovine papillomavirus type 4 (BPV-4) DNA lead to oncogenic transformation of primary bovine cells. Here we show that the synergism between quercetin and BPV-4 (or its E7 oncogene) is stronger the shorter the interval between the two treatments. Quercetin immortalizes transformed cells, confers anchorage-independent growth and induces tumorigenicity in cells transfected only with the E7 oncogene. PMID:7634432

Cairney, M; Campo, M S

1995-08-01

173

Long term exposure to respirable volcanic ash on Montserrat: a time series simulation  

Microsoft Academic Search

Frequent ash fallout from long-lived eruptions (with active phases greater than 5 years) may lead to local populations experiencing\\u000a unacceptably high cumulative exposures to respirable particulate matter. Ash from Montserrat has been shown to contain significant\\u000a levels of cristobalite and other reactive agents that are associated with an increased risk of developing pneumoconiosis (including\\u000a silicosis) and other long-term health problems.

T. K. Hincks; W. P. Aspinall; P. J. Baxter; A. Searl; R. S. J. Sparks; G. Woo

2006-01-01

174

A follow-up study of male exposure to welding and time to pregnancy.  

PubMed

The aim of this study was to estimate whether male welding has an impact on couple fecundability (the probability of conceiving in a menstrual cycle). A sample of Danish couples without previous reproductive experience was recruited nationwide by postal letters to members of the union of metal workers and three other trade unions. Among 430 included couples, 201 males were metal workers and 130 were welders. The couples were followed for a maximum of six menstrual cycles from termination of birth control until a clinical pregnancy was detected. Compared with nonwelding metal workers the fecundability odds ratio (OR) of male exposure to welding was 0.86 (95% confidence interval [CI] 0.58-1.28). An interaction between male smoking and welding was found; within smokers the OR for welding was 0.40 (95% CI 0.17-0.95) and within nonsmokers it was 1.22 (95% CI 0.74-1.99). Previous welding exposure was negatively related to fecundability among smokers (OR 0.84 per year with mild steel welding, OR 0.76 per year with stainless steel welding). No significant results were found when comparing with an external group of nonmetal workers. Decreased fecundability among smoking welders attributable to both current and previous welding exposure is possible, but these findings were the results of subanalyses that were not part of the a priori hypothesis. PMID:9431570

Hjollund, N H; Bonde, J P; Jensen, T K; Henriksen, T B; Kolstad, H A; Ernst, E; Giwercman, A; Pritzl, G; Skakkebaek, N E; Olsen, J

1998-01-01

175

If you could turn back time: understanding transgenerational latent effects of developmental exposure to contaminants.  

PubMed

Latent effects result from embryonic experiences but manifest in later stages of ontogeny. Our objective was to better understand how developmental exposure to contaminants influence life history traits and tolerance to novel stress in the freshwater gastropod, Physa pomilia. Ten egg masses were exposed to each of three initial treatments including control, 2.5 ?g/L cadmium (Cd), and 10 ?g/L Cd; there was no effect of this initial treatment on hatching success. At hatching, snails were transferred to cadmium-free water. Three weeks later, snails were divided among four secondary treatments including control, 50 ?g/L Cd, 150 ?g/L Cd, and 35 °C. Developmental Cd exposure plus secondary temperature stress caused the most adverse effects. Surprisingly, developmental Cd exposure alone was enough to cause significant decreases in reproductive success a generation later. That effects can manifest as transgenerational decrements in reproductive success suggests that latent effects are important and have longer lasting consequences than previously considered. PMID:24121266

Kimberly, David A; Salice, Christopher J

2014-01-01

176

Wait, are you sad or angry? Large exposure time differences required for the categorization of facial expressions of emotion  

PubMed Central

Abstract Facial expressions of emotion are essential components of human behavior, yet little is known about the hierarchical organization of their cognitive analysis. We study the minimum exposure time needed to successfully classify the six classical facial expressions of emotion (joy, surprise, sadness, anger, disgust, fear) plus neutral as seen at different image resolutions (240 × 160 to 15 × 10 pixels). Our results suggest a consistent hierarchical analysis of these facial expressions regardless of the resolution of the stimuli. Happiness and surprise can be recognized after very short exposure times (10–20 ms), even at low resolutions. Fear and anger are recognized the slowest (100–250 ms), even in high-resolution images, suggesting a later computation. Sadness and disgust are recognized in between (70–200 ms). The minimum exposure time required for successful classification of each facial expression correlates with the ability of a human subject to identify it correctly at low resolutions. These results suggest a fast, early computation of expressions represented mostly by low spatial frequencies or global configural cues and a later, slower process for those categories requiring a more fine-grained analysis of the image. We also demonstrate that those expressions that are mostly visible in higher-resolution images are not recognized as accurately. We summarize implications for current computational models.

Du, Shichuan; Martinez, Aleix M.

2013-01-01

177

Leisure time activities related to carcinogen exposure and lung cancer risk in never smokers. A case-control study.  

PubMed

We aim to assess the relationship between leisure time activities related to exposure to carcinogenic substances and lung cancer risk in a hospital-based case-control study performed in never smokers. We included never smoking cases with anatomopathologically confirmed lung cancer and never smoking controls undergoing trivial surgery, at 8 Spanish hospitals. The study was conducted between January 2011 and June 2013. Participants were older than 30 and had no previous neoplasms. All were personally interviewed focusing on lifestyle, environmental tobacco smoke exposure, occupational history and leisure time activities (including duration of such activities). Results were analyzed through logistic regression and adjusted also by residential radon and education level. We included 513 never smokers, 191 cases and 322 controls. The OR for those performing the studied leisure time activities was 1.43 (95%CI 0.78-2.61). When we restricted the analysis to those performing do-it-yourself activities for more than 10 years the OR was 2.21 (95%CI 0.93-5.27). Environmental tobacco smoke exposure did not modify this association. The effect for the different lung cancer histological types was very close to significance for adenocarcinoma but only when these activities were performed for more than 10 years. We encourage health professionals to recommend protective measures for those individuals while performing these hobbies to reduce the risk of lung cancer. PMID:24742725

Ruano-Ravina, Alberto; García-Lavandeira, José Antonio; Torres-Durán, María; Prini-Guadalupe, Luciana; Parente-Lamelas, Isaura; Leiro-Fernández, Virginia; Montero-Martínez, Carmen; González-Barcala, Francisco Javier; Golpe-Gómez, Antonio; Martínez, Cristina; Castro-Añón, Olalla; Mejuto-Martí, María José; Barros-Dios, Juan Miguel

2014-07-01

178

Effect of prolonged isothermal exposure on elevated-temperature, time-dependent fatigue-crack propagation in INCONEL alloy 783  

Microsoft Academic Search

The effect of isothermal exposure on the elevated-temperature, time-dependent fatigue-crack propagation (FCP) in INCONEL Alloy\\u000a 783 is investigated. Commercially produced Alloy 783 was annealed and aged following the standard heat-treatment procedure.\\u000a One set of specimens was then isothermally exposed at 500 °C for 3000 hours. All specimens were subjected to FCP tests with\\u000a various hold-time periods and sustained-loading crack-growth tests

Longzhou Ma; Keh-Minn Chang; Sarwan K. Mannan; Shailesh J. Patel

2002-01-01

179

Variability in Biomarkers of Arsenic Exposure and Metabolism in Adults over Time  

PubMed Central

Background Urinary arsenic metabolites (UAs) are used as biomarkers of exposure and metabolism. Objectives To characterize inter- and intraindividual variability in UAs in healthy individuals. Methods In a longitudinal study conducted in Bangladesh, we collected water and spot urine samples from 196 participants every 3 months for 2 years. Water arsenic (As) was measured by inductively coupled plasma–mass spectrometry and urinary As [arsenite, arsenate, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)] were detected using high-performance liquid chromatography–hydride-generated atomic absorption spectrometry. We used linear mixed-effects models to compute variance components and evaluate the association between UAs and selected factors. Results The concentrations of UAs were fairly reproducible within individuals, with intraclass correlation coefficients (ICCs) of 0.41, 0.35, 0.47, and 0.49 for inorganic As (InAs), MMA, DMA, and total urinary As (TUA). However, when expressed as a ratio, the percent InAs (%InAs), %MMA, and %DMA were poorly reproducible within individuals, with ICCs of 0.16, 0.16, and 0.17, respectively. Arsenic metabolism was significantly associated with sex, exposure, age, smoking, chewing betel nut, urinary creatinine, and season. Specificity and sensitivity analyses showed that a single urine sample adequately classified a participant’s urinary As profile as high or low, but TUA had only moderate specificity for correctly classifying drinking water exposures. Conclusions Epidemiologic studies should use both urinary As concentrations and the relative proportion of UAs to minimize measurement error and to facilitate interpretation of factors that influence As metabolism.

Kile, Molly L.; Hoffman, Elaine; Hsueh, Yu-Mei; Afroz, Sakila; Quamruzzaman, Quazi; Rahman, Mahmuder; Mahiuddin, Golam; Ryan, Louise; Christiani, David C.

2009-01-01

180

Transcriptomic signature to oxidative stress exposure at the time of embryonic genome activation in bovine blastocysts.  

PubMed

In order to understand how in vitro culture affects embryonic quality, we analyzed survival and global gene expression in bovine blastocysts after exposure to increased oxidative stress conditions. Two pro-oxidant agents, one that acts extracellularly by promoting reactive oxygen species (ROS) production (0.01 mM 2,2'-azobis (2-amidinopropane) dihydrochloride [AAPH]) or another that acts intracellularly by inhibiting glutathione synthesis (0.4 mM buthionine sulfoximine [BSO]) were added separately to in vitro culture media from Day 3 (8-16-cell stage) onward. Transcriptomic analysis was then performed on resulting Day-7 blastocysts. In the literature, these two pro-oxidant conditions were shown to induce delayed degeneration in a proportion of Day-8 blastocysts. In our experiment, no morphological difference was visible, but AAPH tended to decrease the blastocyst rate while BSO significantly reduced it, indicating a differential impact on the surviving population. At the transcriptomic level, blastocysts that survived either pro-oxidant exposure showed oxidative stress and an inflammatory response (ARRB2), although AAPH induced higher disturbances in cellular homeostasis (SERPINE1). Functional genomics of the BSO profile, however, identified differential expression of genes related to glycine metabolism and energy metabolism (TPI1). These differential features might be indicative of pre-degenerative blastocysts (IGFBP7) in the AAPH population whereas BSO exposure would select the most viable individuals (TKDP1). Together, these results illustrate how oxidative disruption of pre-attachment development is associated with systematic up-regulation of several metabolic markers. Moreover, it indicates that a better capacity to survive anti-oxidant depletion may allow for the survival of blastocysts with a quieter metabolism after compaction. PMID:23426876

Cagnone, Gael L M; Sirard, Marc-André

2013-04-01

181

Experimental investigation of the effect of stiffness, exposure time and scan direction on the dimension of ultrasound histotripsy lesions.  

PubMed

Histotripsy uses high-intensity focused ultrasound to create energetic bubble clouds inside tissue to liquefy a region and has the advantages of higher contrast B-mode monitoring and sharp borders. This study experimentally investigated the effects of stiffness, exposure time and scan direction on the size of histotripsy-induced lesions in agar samples. A targeted region 0.45 cm wide (lateral) and 0.6 cm deep (axial) was scanned with the step sizes of 0.075 cm and 0.3 cm, respectively. The single-element spherically focused source (1.1 MHz, 6.34 cm focal length, f/1) had the peak compressional and rarefactional pressures of approximately 102 and 17 MPa. Pulses consisted of 20-cycle sine wave tone bursts with a burst period of 3 ms and exposure time of 15, 30 or 60 s. Also, both inward and outward scan direction were tested along the beam axis. The liquefied lesions generally had a larger size than the initially targeted region with larger sizes corresponding to softer agar and longer exposure. There was not a statistically significant difference in the lesion size with scan direction. PMID:21963031

Xu, Jin; Bigelow, Timothy A

2011-11-01

182

The Timing of Prenatal Exposure to Maternal Cortisol and Psychosocial Stress is Associated with Human Infant Cognitive Development  

PubMed Central

The consequences of prenatal maternal stress for infant mental and motor development were examined in 125 full term infants at 3, 6 and12 months of age. Maternal cortisol and psychological state were evaluated five times during pregnancy and at 3, 6 and 12 months postpartum. Exposure to elevated concentrations of cortisol early in gestation was associated with a slower rate of development over the first postnatal year and lower scores on the mental development index of the Bayley Scales of Infant Development (BSID) at 12 months. Elevated levels of maternal cortisol late in gestation, however, were associated with accelerated development over the first year and higher scores on the BSID at 12 months. Elevated levels of maternal pregnancy specific anxiety early in pregnancy were independently associated with lower scores on the BSID at 12 months. These associations could not be explained by postnatal maternal psychological stress, stress related to parenting, prenatal medical history, socioeconomic factors or child race, sex or birth order. These data suggest that maternal cortisol and pregnancy specific anxiety have programming influences on the developing fetus. Prenatal exposure to the same signal, cortisol, had opposite associations with infant development based on the timing of exposure.

Davis, Elysia Poggi; Sandman, Curt A.

2009-01-01

183

Post-exposure sleep deprivation facilitates correctly timed interactions between glucocorticoid and adrenergic systems, which attenuate traumatic stress responses.  

PubMed

Reliable evidence supports the role of sleep in learning and memory processes. In rodents, sleep deprivation (SD) negatively affects consolidation of hippocampus-dependent memories. As memory is integral to post-traumatic stress symptoms, the effects of post-exposure SD on various aspect of the response to stress in a controlled, prospective animal model of post-traumatic stress disorder (PTSD) were evaluated. Rats were deprived of sleep for 6?h throughout the first resting phase after predator scent stress exposure. Behaviors in the elevated plus-maze and acoustic startle response tests were assessed 7 days later, and served for classification into behavioral response groups. Freezing response to a trauma reminder was assessed on day 8. Urine samples were collected daily for corticosterone levels, and heart rate (HR) was also measured. Finally, the impact of manipulating the hypothalamus-pituitary-adrenal axis and adrenergic activity before SD was assessed. Mifepristone (MIFE) and epinephrine (EPI) were administered systemically 10-min post-stress exposure and behavioral responses and response to trauma reminder were measured on days 7-8. Hippocampal expression of glucocorticoid receptors (GRs) and morphological assessment of arborization and dendritic spines were subsequently evaluated. Post-exposure SD effectively ameliorated long-term, stress-induced, PTSD-like behavioral disruptions, reduced trauma reminder freezing responses, and decreased hippocampal expression of GR compared with exposed-untreated controls. Although urine corticosterone levels were significantly elevated 1?h after SD and the HR was attenuated, antagonizing GRs with MIFE or stimulation of adrenergic activity with EPI effectively abolished the effect of SD. MIFE- and EPI-treated animals clearly demonstrated significantly lower total dendritic length, fewer branches and lower spine density along dentate gyrus dendrites with increased levels of GR expression 8 days after exposure, as compared with exposed-SD animals. Intentional prevention of sleep in the early aftermath of stress exposure may well be beneficial in attenuating traumatic stress-related sequelae. Post-exposure SD may disrupt the consolidation of aversive or fearful memories by facilitating correctly timed interactions between glucocorticoid and adrenergic systems. PMID:22713910

Cohen, Shlomi; Kozlovsky, Nitsan; Matar, Michael A; Kaplan, Zeev; Zohar, Joseph; Cohen, Hagit

2012-10-01

184

Improvement of attention span and reaction time with hyperbaric oxygen treatment in patients with toxic injury due to mold exposure.  

PubMed

It is, by now, well established that mold toxins (mycotoxins) can cause significant adverse health effects. In this study, 15 subjects who developed an attention deficit disorder (ADD) and slowing of reaction time at the time of exposure to mold toxins were identified. Deficits in attention span and reaction time were documented not only by taking a careful history, but also by performing a Test of Variables of Attention (TOVA). The TOVA test provides an objective measure of these two variables. It was found that mold-exposed subjects show statistically significant decreases in attention span and significant increases in reaction time to stimuli compared to controls. After ten sessions of hyperbaric oxygen treatment (HBOT), a statistically significant improvement was seen in both measures. This preliminary study suggests promising outcomes in treating mold-exposed patients with hyperbaric oxygen. PMID:20978814

Ezra, N; Dang, K; Heuser, G

2011-01-01

185

Improvement of attention span and reaction time with hyperbaric oxygen treatment in patients with toxic injury due to mold exposure  

PubMed Central

It is, by now, well established that mold toxins (mycotoxins) can cause significant adverse health effects. In this study, 15 subjects who developed an attention deficit disorder (ADD) and slowing of reaction time at the time of exposure to mold toxins were identified. Deficits in attention span and reaction time were documented not only by taking a careful history, but also by performing a Test of Variables of Attention (TOVA). The TOVA test provides an objective measure of these two variables. It was found that mold-exposed subjects show statistically significant decreases in attention span and significant increases in reaction time to stimuli compared to controls. After ten sessions of hyperbaric oxygen treatment (HBOT), a statistically significant improvement was seen in both measures. This preliminary study suggests promising outcomes in treating mold-exposed patients with hyperbaric oxygen.

Ezra, N.; Dang, K.

2010-01-01

186

Germination response of MR 219 rice variety to different exposure times and periods of 2450 MHz microwave frequency.  

PubMed

Germination is a key process in plants' phenological cycles. Accelerating this process could lead to improvment of the seedling growth as well as the cultivation efficiency. To achieve this, the effect of microwave frequency on the germination of rice seeds was examined. The physiological feedbacks of the MR 219 rice variety in terms of seed germination rate (GR), germination percentage (GP), and mean germination time (MGT) were analyzed by exposing its seeds to 2450 MHz of microwave frequency for one, four, seven, and ten hours. It was revealed that exposing the seeds to the microwave frequency for 10 hours resulted in the highest GP. This treatment led to 100% of germination after three days with a mean germination time of 2.1 days. Although the other exposure times of microwave frequency caused the moderate effects on germination with a GP(a3) ranged from 93% to 98%, they failed to reduce the MGT(a3). The results showed that ten-hour exposure times of microwave frequency for six days significantly facilitated and improved the germination indices (primary shoot and root length). Therefore, the technique is expected to benefit the improvement of rice seed germination considering its simplicity and efficacy in increasing the germination percentage and rate as well as the primary shoot and root length without causing any environmental toxicity. PMID:24307869

Talei, Daryush; Valdiani, Alireza; Maziah, Mahmood; Mohsenkhah, Mohammad

2013-01-01

187

Effect of prolonged isothermal exposure on elevated-temperature, time-dependent fatigue-crack propagation in INCONEL alloy 783  

NASA Astrophysics Data System (ADS)

The effect of isothermal exposure on the elevated-temperature, time-dependent fatigue-crack propagation (FCP) in INCONEL Alloy 783 is investigated. Commercially produced Alloy 783 was annealed and aged following the standard heat-treatment procedure. One set of specimens was then isothermally exposed at 500 °C for 3000 hours. All specimens were subjected to FCP tests with various hold-time periods and sustained-loading crack-growth tests at 538 °C and 650 °C in a laboratory-air environment. Without a hold time, the as-produced and isothermally exposed materials had comparable FCP rates at both test temperatures. With hold times of 100 and 300 seconds, the as-produced and isothermally exposed specimens had comparable FCP rates at 538 °C. Hold-time testing of the as-produced material at 650 °C showed abnormal time-dependent FCP and sustained-loading crack-growth retardation. However, hold-time testing of isothermally exposed material at 650 °C showed the steady sustained-loading crack growth and fully time-dependent FCP typically observed in many superalloys. Comparison with Alloy 718 data from the literature shows that FCP rates of as-produced Alloy 718 and isothermally exposed Alloy 783 are comparable at 650 °C. A fully time-dependent FCP model based on the damage-zone concept and a thermal-activation equation is proposed to characterize the FCP behaviors.

Ma, Longzhou; Chang, Keh-Minn; Mannan, Sarwan K.; Patel, Shailesh J.

2002-11-01

188

RELATIONSHIPS BETWEEN AMBIENT CONCENTRATION AND PERSONAL EXPOSURE (AMBIENT, NONAMBIENT, AND TOTAL) AND THEIR USE AS EXPOSURE SURROGATES IN PM COMMUNITY TIME SERIES EPIDEMIOLOGY  

EPA Science Inventory

As a result of a literature review use in preparation of the Exposure chapter for the 1996 Air Quality Criteria for Particulate Matter, NCEA staff begin a project to analyze the relationships between personal exposures (to ambient, nonambient and total) PM and ambient concentrati...

189

Individual-level PM?.? exposure and the time course of impaired heart rate variability: the APACR Study.  

PubMed

In 106 community-dwelling middle-aged non-smokers we examined the time-course and the acute effects of fine particles (PM?.?) on heart rate variability (HRV), which measures cardiac autonomic modulation (CAM). Twenty-four hours beat-to-beat ECG data were visually examined. Artifacts and arrhythmic beats were removed. Normal beat-to-beat RR data were used to calculate HRV indices. Personal PM?.? nephelometry was used to estimate 24-h individual-level real-time PM?.? exposures. We use linear mixed-effects models to assess autocorrelation- and other major confounder-adjusted regression coefficients between 1-6?h moving averages of PM?.? and HRV indices. The increases in preceding 1-6?h moving averages of PM?.? was significantly associated with lower HF, LF, and SDNN, with the largest effect size at 4-6?h moving averages and smallest effects size at 1?h moving average. For example, a 10??g/m³ increase in 1 and 6-h moving averages was associated with 0.027 and 0.068?ms² decrease in log-HF, respectively, and with 0.024 and 0.071?ms² decrease in log-LF, respectively, and with 0.81 and 1.75?ms decrease in SDNN, respectively (all P-values <0.05). PM?.? exposures are associated with immediate impairment of CAM. With a time-course of within 6?h after elevated PM?.? exposure, with the largest effects around 4-6?h. PMID:20372190

He, Fan; Shaffer, Michele L; Li, Xian; Rodriguez-Colon, Sol; Wolbrette, Deborah L; Williams, Ronald; Cascio, Wayne E; Liao, Duanping

2011-01-01

190

Lateral distribution of the degradation of encapsulants after different damp-heat exposure times investigated by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

PV modules have to have a service lifetime of more than 20 years. It is hard to follow suitable degradation indicators during service life testing with sufficient accuracy for reliable service life estimation. Often the polymeric encapsulation material, mostly ethylene vinyl acetate, shows degradation effects. The detection of small changes of the material in a non-destructive manner helps to follow the changes over time during indoor testing. PV modules with crystalline Si-cells of seven German manufacturers were analyzed after accelerated ageing tests with Raman spectroscopy. This technology allows non-destructive measurements of the encapsulation material through the glazing so that the degradation of the samples can be followed by measuring after different exposure times. Samples had been exposed to damp-heat conditions for up to 4000 h. The results show significant differences in the materials degradation above the edges and the center of the cell. With increasing exposure times, it becomes apparent that the degradation process starts near the edges of the cells and propagates towards the center, indicating the impact of diffusion processes.

Peike, C.; Kaltenbach, T.; Köhl, M.; Weiß, K.-A.

2010-08-01

191

Electron microscopy and microanalysis of steel weld joints after long time exposures at high temperatures  

NASA Astrophysics Data System (ADS)

The structural changes of three trial weld joints of creep resistant modified 9Cr-1Mo steels and low alloyed chromium steel after post-weld heat treatment and long-term creep tests were investigated. Smooth cross-weld specimens ruptured in different zones of the weld joints as a result of different structural changes taking place during creep exposures. The microstructure of the weld joint is heterogeneous and consequently microstructural development can be different in the weld metal, the heat affected zone, and the base material. Precipitation reactions, nucleation and growth of some particles and dissolution of others, affect the strengthening of the matrix, recovery at high temperatures, and the resulting creep resistance. Therefore, a detailed study of secondary phase's development in individual zones of weld joints can elucidate mechanism of cracks propagation in specific regions and the causes of creep failure. Type I and II fractures in the weld metal and Type IV fractures in the fine prior austenite grain heat affected zones occurred after creep tests at temperatures ranging from 525 to 625 °C and under stresses from 40 to 240 MPa. An extended metallographic study of the weld joints was carried out using scanning and transmission electron microscopy, energy-dispersive and wave-dispersive X-ray microanalysis. Carbon extraction replicas and thin foils were prepared from individual weld joint regions and quantitative evaluation of dislocation substructure and particles of secondary phases has been performed.

Jandová, D.; Kasl, J.; Rek, A.

2010-02-01

192

Response of Vibrio fischeri to repeated exposures over time in an Online Toxicity Monitor  

EPA Science Inventory

Online Toxicity Monitors have been developed to provide continuous, time-relevant information regarding water quality. These systems measure a physiological or behavioral response of a sentinel organism to changes water quality. One such system, the Microlan Toxcontrol, is base...

193

Modeling Exposure to Electromagnetic Fields with Realistic Anatomical Models: The Brooks Finite Difference Time Domain (FDTD).  

National Technical Information Service (NTIS)

Air Force Research Laboratory/Human Effectiveness Directorate Radio Frequency Radiation Branch (AFRL/RHDR) and Naval Health Research Center (NHRC) have long used Finite Difference Time Domain (FDTD) software to study radiofrequency radiation (RF) bioeffec...

J. Payne J. Ziriax L. Harris S. Adams

2008-01-01

194

The Impact of Timing of Exposure to Violence on Violent Behavior in a High Poverty Sample of Inner City African American Youth  

ERIC Educational Resources Information Center

A growing body of research has linked exposure to violence to violent behavior, but few studies have examined the impact of the timing of exposure to violence on violent behavior among inner city, minority youth. Theoretical insights derived from developmental psychology and psychopathology (DPP) and Agnew's general strain theory (GST) give…

Spano, Richard; Rivera, Craig; Bolland, John

2006-01-01

195

Adult asthma and traffic exposure at residential address, workplace address, and self-reported daily time outdoor in traffic: A two-stage case-control study  

Microsoft Academic Search

BACKGROUND: Most epidemiologic studies use traffic at residential address as a surrogate for total traffic exposure when investigating effects of traffic on respiratory health. This study used GIS (Geographical Information Systems) to estimate traffic exposure, not only on residential, but also on workplace address, in addition to survey questions on time spent in traffic during commuting or other daily activities.

Anna Lindgren; Jonas Björk; Emilie Stroh; Kristina Jakobsson

2010-01-01

196

Time to pregnancy and exposure to pesticides in Danish farmers. ASCLEPIOS Study Group  

Microsoft Academic Search

OBJECTIVE: Circumstantial evidence suggests that organic farmers may have higher sperm count than other men, but comprehensive epidemiological studies of male fecundity among farmers have never been carried out. A substantial increase of sperm count is expected to translate into a shorter time to pregnancy--the number of menstrual cycles or months it takes a couple to get pregnant from discontinuation

S. B. Larsen; M. Joffe; J. P. Bonde

1998-01-01

197

64 FR 13686 - Radiation Exposure Compensation Act: Evidentiary Requirements; Definitions; and Number of Times...  

Federal Register 2010, 2011, 2012, 2013

...that he or she stopped smoking at least fifteen (15...diagnosis of primary cancer of the esophagus, pharynx...and did not resume smoking at any time thereafter...that he or she stopped smoking at least fifteen (15...diagnosis of primary cancer of the lung,...

1999-03-22

198

The Impact of Sleep Timing and Bright Light Exposure on Attentional Impairment during Night Work  

Microsoft Academic Search

The prevalence of hazardous incidents induced by attentional impairment during night work and ensuing commute times is attributable to circadian misalignment and increased sleep pressure. In a 10-day shift work simulation protocol (4 day shifts and 3 night shifts), the efficacies of 2 countermeasures against nighttime (2300 to 0700 h) attentional impairment were compared: (1) Morning Sleep (0800 to 1600

Nayantara Santhi; Daniel Aeschbach; Todd S. Horowitz; Charles A. Czeisler

2008-01-01

199

THE EXPOSURE PARADOX IN PARTICULATE MATTER COMMUNITY TIME-SERIES EPIDEMIOLOGY: CAN AMBIENT CONCENTRATIONS OF PM BE USED AS A SURROGATE FOR PERSONAL EXPOSURE TO PM ?  

EPA Science Inventory

Objective: Explain why epidemiologic studies find a statistically significant relationship between ambient concentrations of PM and health effects even though only a near-zero correlation is found between ambient concentrations of PM and personal exposures to PM. Method: Consider...

200

The Time of Prenatal Androgen Exposure Affects Development of Polycystic Ovary Syndrome-Like Phenotype in Adulthood in Female Rats  

PubMed Central

Background: Polycystic ovary syndrome (PCOS) is one of the most common reproductive disorders in women. Previous studies have shown that prenatal exposure of female fetuses to androgen can be considered an important factor in the development of PCOS. Objectives: In the present study we aimed to examine the effects of prenatal exposure of female rat fetuses to previously documented doses of testosterone on different embryonic days on the development of PCOS phenotype in adulthood. Materials and Methods: Pregnant rats were divided into four groups, experimental and control groups. Three mg of free testosterone was administered subcutaneously to experimental group 1 on gestational days 16-19, daily and 20 mg on day 20, to experimental group 2, and the controls received solvent at the same times. Female offspring of these mothers aged between 90-100 days were examined for development and function of the reproductive system. Independent-sample student t test was used to compare the results between the experimental groups and controls. Results: Anogenital distance (P < 0.001) and clitoris length were significantly increased in the offspring of both experimental groups (P < 0.001 and P < 0.05 respectively). Nipples were not formed in the offspring of experimental group 1, whereas in experimental group 2 the number of nipples was unchanged. Vaginal length was significantly decreased in the offspring of experimental group 1 (P < 0.001), whereas in experimental group 2, no significant difference was observed. In the offspring of experimental group 1, hormonal profiles did not differ, but in experimental group 2, levels of testosterone (P < 0.05) and LH (P < 0.01) were significantly increased, but estrogen (P < 0.05) and anti-Mullerian hormone levels (P < 0.001) were significantly decreased. A significant increase in the number of preantral and antral follicles was observed in the ovaries of offspring of experimental group 1 (P < 0.05); whereas there was no such a difference in experimental group 2. Conclusions: The time of prenatal exposure to androgens may have a significant role in the development of PCOS. Increased prenatal androgen levels are associated with hormonal changes and morphological disorders of the reproductive system. Therefore, avoiding exposure to androgen excess during critical periods of fetal development may prevent or reduce adulthood PCOS manifestations caused by prenatal excess androgen.

Ramezani Tehrani, Fahimeh; Noroozzadeh, Mahsa; Zahediasl, Saleh; Piryaei, Abbas; Hashemi, Somayeh; Azizi, Fereidoun

2014-01-01

201

Long-term exposure to mobile communication radiation: an analysis of time-variability of electric field level in GSM900 downlink channels.  

PubMed

Interest for knowing long-term human exposure levels due to mobile communications has increased in the last years. It has been shown that short-term exposure assessment made under standard procedural restrictions is not reliable when it comes to conclusions on long-term exposure levels. The present work is the result of a several week analysis of time variability of electric field level inside traffic and control channels of the GSM900 mobile communication downlink band and it indicates that a temporal model to allow future predictions of exposure on the long run is obtainable. Collecting, processing and statistically analysing the data provide expression of the maximum and weighted field strengths and their evolution in time. Specific electromagnetic footprints of the channels have been extracted, differentiations between their characteristics have been emphasised and practical advice is provided, with the scope of contributing to the development of reliable procedures for long-term exposure assessment. PMID:22908352

Miclaus, Simona; Bechet, Paul; Gheorghevici, Marius

2013-04-01

202

Time Exposure Period of Bovine Oocytes to Sperm in Relation to Embryo Development Rate and Quality  

PubMed Central

The objective of the study was to determine the effect of different bovine gamete coincubation times on fertilization and embryo development performance. In vitro matured COCs were co-incubated with sperm at a concentration of 1.5 × 106 spermatozoa/ml in TALP medium for 3 hours (T 3, n = 362), 6 hours (T 6, n = 358), or 18 hours (T 18, n = 350). At the end of the coincubation period COCs from times 3 and 6 groups were post-incubated in a new well of fertilization medium without sperm for additional 15 and 12 h, respectively. Cumulus Oocyte Complexes from the T 18 were co-incubated with the sperm suspension for 18 hours. Presumptive zygotes were cultured for 9 days and embryo development was evaluated on days 2, 8, and 9. Thirty blastocysts from each group were stained and total number of nuclei was recorded. The mean (± SEM) percentages of zygotes to develop into ?2 cell stage were 71.9 ± 5.0; 72.5 ± 5.3 and 81.2 ± 6.1 % for T 3, 6, and 18, respectively, on day 2 and they did not differ (P = .3) among groups. The mean percentage of blastocysts developed on day 8 (25.6 ± 2.8; 24.2 ± 3.3; 28.4 ± 4.2 % for T 3, 6, and 18, resp.) did not differ (P = .4) among groups. The total number of embryonic nuclei was greater (P < .05) for the blastocysts produced from the shortest co-incubation time (T 3).

Berland, Marco; Frei, Mario; Peralta, Oscar; Ratto, Marcelo

2011-01-01

203

A simulation study on effects of exposure to a combination of pesticides used in an orchard and tuber crop on the recovery time of a vulnerable aquatic invertebrate.  

PubMed

The aim of the present study was to assess whether population effects and recovery times increase when a population of a vulnerable aquatic invertebrate is exposed to concentrations of 1 or multiple pesticides. The 2 sets of pesticide combinations tested are typical for orchard and tuber crops in The Netherlands. Exposure concentrations were predicted using the FOCUS step 3 modeling framework and the Dutch drainage ditch scenario. Recovery times were assessed using the MASTEP population model. We simulated the population dynamics and pesticide effects in a Monte Carlo style by using median effective concentration values drawn from an arthropod species sensitivity distribution. In the tuber scenario, exposure to ?-cyhalothrin resulted in long-term effects, whereas exposure to the co-occurring compound fluazinam hardly resulted in (additional) effects. In the orchard scenario, 3 pesticides resulted in large effects just after exposure, but pulse exposures to these compounds did not coincide. The probabilities of effects for the single compounds added up for the combination; in contrast, the recovery times were not higher for the combination compared to those associated with exposure to the individual compounds. The conclusion from the present study's simulations is that exposure to the evaluated pesticide packages may lead to increased mortality probabilities and effect sizes of the combination, but does not lead to longer recovery times for populations with synchronized reproduction than when exposed to the individual compounds. Environ Toxicol Chem 2014;33:1489-1498. © 2013 SETAC. PMID:24375456

Focks, Andreas; Luttik, Robert; Zorn, Mathilde; Brock, Theo; Roex, Erwin; Van der Linden, Ton; Brink, Paul J Van den

2014-07-01

204

Time-location analysis for exposure assessment studies of children using a novel global positioning system instrument.  

PubMed Central

Global positioning system (GPS) technology is used widely for business and leisure activities and offers promise for human time-location studies to evaluate potential exposure to environmental contaminants. In this article we describe the development of a novel GPS instrument suitable for tracking the movements of young children. Eleven children in the Seattle area (2-8 years old) wore custom-designed data-logging GPS units integrated into clothing. Location data were transferred into geographic information systems software for map overlay, visualization, and tabular analysis. Data were grouped into five location categories (in vehicle, inside house, inside school, inside business, and outside) to determine time spent and percentage reception in each location. Additional experiments focused on spatial resolution, reception efficiency in typical environments, and sources of signal interference. Significant signal interference occurred only inside concrete/steel-frame buildings and inside a power substation. The GPS instruments provided adequate spatial resolution (typically about 2-3 m outdoors and 4-5 m indoors) to locate subjects within distinct microenvironments and distinguish a variety of human activities. Reception experiments showed that location could be tracked outside, proximal to buildings, and inside some buildings. Specific location information could identify movement in a single room inside a home, on a playground, or along a fence line. The instrument, worn in a vest or in bib overalls, was accepted by children and parents. Durability of the wiring was improved early in the study to correct breakage problems. The use of GPS technology offers a new level of accuracy for direct quantification of time-location activity patterns in exposure assessment studies.

Elgethun, Kai; Fenske, Richard A; Yost, Michael G; Palcisko, Gary J

2003-01-01

205

Power law signature of media exposure in human response waiting time distributions.  

PubMed

We study the humanitarian response to the destruction brought by the tsunami generated by the Sumatra earthquake of December 26, 2004, as measured by donations, and find that it decays in time as a power law ?1/t? with ?=2.5 ± 0.1 . This behavior is suggested to be the rare outcome of a priority queuing process in which individuals execute tasks at a rate slightly faster than the rate at which new tasks arise. We believe this to be an empirical evidence documenting the recently predicted [G. Grinstein and R. Linsker, Phys. Rev. E 77, 012101 (2008)] regime, and provide additional independent evidence that suggests that this "highly attentive regime" arises as a result of the intense focus placed on this donation "task" by the media. PMID:20866291

Crane, Riley; Schweitzer, Frank; Sornette, Didier

2010-05-01

206

Power law signature of media exposure in human response waiting time distributions  

NASA Astrophysics Data System (ADS)

We study the humanitarian response to the destruction brought by the tsunami generated by the Sumatra earthquake of December 26, 2004, as measured by donations, and find that it decays in time as a power law ˜1/t? with ?=2.5±0.1 . This behavior is suggested to be the rare outcome of a priority queuing process in which individuals execute tasks at a rate slightly faster than the rate at which new tasks arise. We believe this to be an empirical evidence documenting the recently predicted [G. Grinstein and R. Linsker, Phys. Rev. E 77, 012101 (2008)] regime, and provide additional independent evidence that suggests that this “highly attentive regime” arises as a result of the intense focus placed on this donation “task” by the media.

Crane, Riley; Schweitzer, Frank; Sornette, Didier

2010-05-01

207

Time of exposure and risk of HIV infection in homosexual partners of men with AIDS.  

PubMed Central

We interviewed, and tested for HIV antibody, 117 homosexual men who had been regular sexual partners of men who developed acquired immunodeficiency syndrome (AIDS); 85 tested seropositive. Receptive anal intercourse with the index AIDS case and number of different sexual partners with whom subjects were anally receptive were both risk factors. Controlling for the number of partners with whom subjects were anally receptive, we found that the odds ratio of receptive anal intercourse with the case was infinite (95% confidence intervals, 3.3-infinity) if sexual contact continued up to or beyond the time of diagnosis, while the odds ratio was 1.0 (95% CI 0.3-3.2) if contact ceased before the case's AIDS diagnosis. Risk was not associated with the duration or frequency of contact. Our data suggest that the potential for sexual transmission from an HIV-infected person may be greater close to or after the onset of disease.

Osmond, D; Bacchetti, P; Chaisson, R E; Kelly, T; Stempel, R; Carlson, J; Moss, A R

1988-01-01

208

Timing and intensity of exposure to interferon-? critically determines the function of monocyte-derived dendritic cells.  

PubMed

A growing body of evidence suggests that inflammatory cytokines have a dualistic role in immunity. In this study, we sought to determine the direct effects of interferon-? (IFN-?) on the differentiation and maturation of human peripheral blood monocyte-derived dendritic cells (moDC). Here, we report that following differentiation of monocytes into moDC with granulocyte-macrophage colony-stimulating factor and interleukin-4, IFN-? induces moDC maturation and up-regulates the co-stimulatory markers CD80/CD86/CD95 and MHC Class I, enabling moDC to effectively generate antigen-specific CD4(+) and CD8(+) T-cell responses for multiple viral and tumour antigens. Early exposure of monocytes to high concentrations of IFN-? during differentiation promotes the formation of macrophages. However, under low concentrations of IFN-?, monocytes continue to differentiate into dendritic cells possessing a unique gene-expression profile, resulting in impairments in subsequent maturation by IFN-? or lipopolysaccharide and an inability to generate effective antigen-specific CD4(+) and CD8(+) T-cell responses. These findings demonstrate that IFN-? imparts differential programmes on moDC that shape the antigen-specific T-cell responses they induce. Timing and intensity of exposure to IFN-? can therefore determine the functional capacity of moDC. PMID:24678989

Kerkar, Sid P; Chinnasamy, Dhanalakshmi; Hadi, Neima; Melenhorst, Jan; Muranski, Pawel; Spyridonidis, Alexandros; Ito, Sawa; Weber, Gerrit; Yin, Fang; Hensel, Nancy; Wang, Ena; Marincola, Francesco M; Barrett, Austin John

2014-09-01

209

Developmental Timing and Continuity of Exposure to Interparental Violence and Externalizing Behavior as Prospective Predictors of Dating Violence  

PubMed Central

This study investigated the prospective pathways of children's exposure to interparental violence (EIPV) in early and middle childhood and externalizing behavior in middle childhood and adolescence as developmental predictors of dating violence perpetration and victimization at ages 23 and 26 years. Participants (N = 168) were drawn from a longitudinal study of low-income families. Path analyses examined whether timing or continuity of EIPV predicted dating violence and whether timing or continuity of externalizing behavior mediated these pathways. Results indicated that EIPV in early childhood directly predicted perpetration and victimization at age 23. There were significant indirect effects from EIPV to dating violence through externalizing behavior in adolescence and life stress at age 23. Independent of EIPV, externalizing behavior in middle childhood also predicted dating violence through externalizing behavior in adolescence and life stress at age 23, but this pathway stemmed from maltreatment. These results highlight that the timing of EIPV and both the timing and continuity of externalizing behavior are critical risks for the intergenerational transmission of dating violence. Findings support a developmental perspective that negative early experiences and children's externalizing behavior are powerful influences for dating violence in early adulthood.

Narayan, Angela J.; Englund, Michelle M.; Egeland, Byron

2014-01-01

210

Evidence that high-dosage zidovudine at time of retrovirus exposure reduces antiviral efficacy.  

PubMed Central

The antiviral efficacy of prophylactic 3'-azido-3'-deoxythymidine (AZT) therapy administered by continuous infusion or intermittent injection was compared in pediatric cats infected with feline leukemia virus. A 4-week treatment regimen of AZT was initiated at -48, 8, or 96 h postinfection (p.i.). For AZT therapy begun at -48 h p.i., significant efficacy was attained when therapy was given by continuous infusion but not by intermittent injection. However, when AZT therapy was delayed until 96 h p.i., both continuous infusion and intermittent injection gave complete protection. The results suggest that intermittent AZT administration is less efficacious than continuous infusion. Higher peak AZT concentrations in plasma associated with intermittent injection compared with those associated with continuous infusion may be immunotoxic, thus reducing the drug-induced vaccine effect. Furthermore, AZT toxicity seemed to be restricted to a window of sensitivity close to the time of virus challenge because delaying the start of AZT therapy until 96 h p.i. was highly efficacious, regardless of the method of administration.

Mathes, L E; Hayes, K A; Kociba, G

1996-01-01

211

Timing of Concussion Diagnosis is Related to Head Impact Exposure Prior to Injury  

PubMed Central

Purpose Concussions are commonly undiagnosed in an athletic environment because the post-injury signs and symptoms may be mild, masked by the subject, or unrecognized. This study compares measures of head impact frequency, location and kinematic response prior to cases of immediate and delayed concussion diagnosis. Methods Football players from eight collegiate and six high school teams wore instrumented helmets during play (n=1,208), of which ninety-five were diagnosed with concussion (105 total cases). Acceleration data recorded by the instrumented helmets was reduced to five kinematic metrics: peak linear and rotational acceleration, GSI, HIC15, and change in head velocity (?v). Additionally, each impact was assigned to one of four general location regions (Front, Back, Side, and Top), and the number of impacts sustained prior to injury was calculated over two time periods (one and seven days). Results All head kinematic measures associated with injury, except peak rotational acceleration (p = 0.284), were significantly higher for cases of immediate diagnosis than delayed diagnosis (p<0.05). Players with delayed diagnosis sustained a significantly higher number of head impacts on the day of injury (32.9 ±24.9; p < 0.001) and within seven days of injury (69.7 ±43.3; p = 0.006) than players with immediate diagnosis (16.5 ±15.1 and 50.2 ±43.6). Impacts associated with concussion occurred most frequently to the Front of the head (46%) followed by the Top (25%), Side (16%), and Back (13%) with the number of impacts by location independent of temporal diagnosis (?2(3) = 4.72; p = 0.19). Conclusions Concussions diagnosed immediately after an impact event are associated with the highest kinematic measures, while those characterized by delayed diagnosis are preceded by a higher number of impacts.

Beckwith, Jonathan G.; Greenwald, Richard M.; Chu, Jeffrey J.; Crisco, Joseph J.; Rowson, Steven; Duma, Stefan M.; Broglio, Steven P.; McAllister, Thomas W.; Guskiewicz, Kevin M.; Mihalik, Jason P.; Anderson, Scott; Schnebel, Brock; Brolinson, P. Gunnar; Collins, Michael W.

2012-01-01

212

Short-time glucose exposure of embryonic carcinoma cells impairs their function as terminally differentiated cardiomyocytes.  

PubMed

The fetal and postnatal phenotype is influenced by developmental conditions experienced prenatally. Among prenatal development metabolic factors are of particular importance as they are supposed to predispose for pathophysiological alterations later in life and to pioneer functional impairment in senescence (metabolic programming). Till now the mechanisms of metabolic programming are not well understood. We have investigated various concentrations of glucose during differentiation of pluripotent P19 embryonic carcinoma cells (ECC) into cardiomyocytes. Undifferentiated P19 cells were exposed to 5mM (low), 25 mM (control), 40 mM or 100mM (high) glucose for 48 h during embryoid body (EB) formation, followed by plating and differentiation into cardiomyocytes in vitro with standard glucose supplementation (25 mM) for 10-15 days. The amount of cardiac clusters, the frequency of spontaneous beatings as well as the expression of metabolic and cardiac marker genes and their promoter methylation were measured. We observed a metabolic programming effect of glucose during cardiac differentiation. Whereas the number of beating clusters and the expression of the cardiac marker alpha myosin heavy chain (?-MHC) were comparable in all groups, the frequencies of beating clusters were significantly higher in the high glucose group compared to low glucose. However, neither the insulin receptor (IR) or insulin like growth factor 1 receptor (IGF1R) nor the metabolic gene glucose transporter 4 (GLUT4) were influenced in RNA expression or in promoter methylation. Our data indicate that a short time glucose stress during embryonic cell determination leads to lasting effects in terminally differentiated cell function. PMID:22405827

Knelangen, Julia M; Kurz, Randy; Schagdarsurengin, Undraga; Fischer, Bernd; Navarrete Santos, Anne

2012-04-01

213

WNT3A Promotes Hematopoietic or Mesenchymal Differentiation from hESCs Depending on the Time of Exposure  

PubMed Central

We investigated the role of canonical WNT signaling in mesoderm and hematopoietic development from human embryonic stem cells (hESCs) using a recombinant human protein-based differentiation medium (APEL). In contrast to prior studies using less defined culture conditions, we found that WNT3A alone was a poor inducer of mesoderm. However, WNT3A synergized with BMP4 to accelerate mesoderm formation, increase embryoid body size, and increase the number of hematopoietic blast colonies. Interestingly, inclusion of WNT3A or a GSK3 inhibitor in methylcellulose colony-forming assays at 4 days of differentiation abrogated blast colony formation but supported the generation of mesospheres that expressed genes associated with mesenchymal lineages. Mesospheres differentiated into cells with characteristics of bone, fat, and smooth muscle. These studies identify distinct effects for WNT3A, supporting the formation of hematopoietic or mesenchymal lineages from human embryonic stem cells, depending upon differentiation stage at the time of exposure.

Gertow, Karin; Hirst, Claire E.; Yu, Qing C.; Ng, Elizabeth S.; Pereira, Lloyd A.; Davis, Richard P.; Stanley, Edouard G.; Elefanty, Andrew G.

2013-01-01

214

Short-term neonatal/prepubertal exposure of dibutyl phthalate (DBP) advanced pubertal timing and affected hypothalamic kisspeptin/GPR54 expression differently in female rats.  

PubMed

Dibutyl phthalate (DBP) had been widely used and its exposure in children has been thought to be one of the reasons causing a trend of advanced pubertal timing in girls. Puberty starts from hypothalamic gonadotropin-releasing hormone release which is controlled by many factors including neurotransmitter kisspeptin and its receptor GPR54. These neural organization or reorganization happens in hypothalamus during neonatal or prepubertal period which may be two target windows of DBP exposure. The present study was designed to determine: (1) the difference between the effects of neonatal and prepubertal DBP exposure on female pubertal timing; (2) whether kisspeptin/GPR54 expression in hypothalamus would respond to neonatal and prepubertal DBP exposure differently. Female Sprague-Dawley rats were exposed by subcutaneous injection of 0.5, 5 and 50mg/kg DBP during Postnatal day (P)1-5 (neonatal) or P26-30 (prepubertal). Physiological data demonstrated that both neonatal and prepubertal DBP exposure could advance pubertal timing significantly accompanied by irregular estrous cycles but only a little gonadal impairment. Exposure-period-related difference was found significant with prepubertal exposure groups having longer estrous cycle duration, heavier at vaginal opening and having higher serum estradiol level compared with neonatal exposure groups. Molecular data showed an up-regulated trend in kisspeptin mRNA and immunoreactivity levels of hypothalamic area arcuate but a down-regulation in GPR54 mRNA expression after P1-5 DBP treatment. In P26-30 groups, kisspeptin mRNA and immunoreactivity levels tended to be lower after DBP treatment. These results demonstrated small dose of DBP could induce earlier pubertal timing in females and both neonatal and prepubertal periods were critical windows for DBP exposure. PMID:24056307

Hu, Jialei; Du, Guizhen; Zhang, Wei; Huang, Hongyu; Chen, Danni; Wu, Di; Wang, Xinru

2013-12-01

215

Bioaccumulation of polychlorinated dibenzo-p-dioxins in sediment by oligochaetes: Influence of exposure pathway and contact time  

SciTech Connect

Oligochaetes (Lumbriculus variegatus) were exposed simultaneously to radiolabeled [{sup 3}H]2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and [{sup 14}C]octachlorodibenzo-p-dioxin (OCDD) in sediment for 28 d, in order to study accumulation processes of hydrophobic substances. Elimination was studied for a further 20 d. The uptake and elimination rate constants and the bioaccumulation factors (BAFs) were determined for TCDD and OCDD in the presence and absence of sediment (overlying water). Steady-state concentrations in oligochaetes were achieved for TCDD but not for OCDD over the 28-d exposure. Biota-sediment accumulation factors (BSAFs) after a 28-d exposure were 1.6 {+-} 0.27 for TCDD and 0.07 {+-} 0.02 for OCDD. Steady-state log BAF values (lipid based) for TCDD and OCDD in oligochaetes in the overlying water were 5.9 and 5.5 L/kg, respectively. The effect of incubation time between sediment and contaminants was investigated by repeating the accumulation study after a contact period of 21 months. BSAFs of sediment-sorbed TCDD and OCDD were 1.5 to 2-fold lower for the long contact time sediment. Based on comparison of predicted accumulation from pore water and observed accumulation by sediment-exposed oligochaetes, it was concluded that 1.4-fold greater accumulation occurred due to assimilation of TCDD and OCDD from ingested sediment. This additional accumulation in the presence of sediment, not accounted for by uptake only from pore waters, was consistent with literature data for other hydrophobic organochlorines.

Loonen, H.; Parsons, J.R.; Govers, H.A.J. [Univ. of Amsterdam (Netherlands). Dept. of Environmental and Toxicological Chemistry; Muir, D.C.G. [Dept. of Fisheries and Oceans, Winnipeg, Manitoba (Canada). Freshwater Inst.

1997-07-01

216

Assessment of radiopacity of restorative composite resins with various target distances and exposure times and a modified aluminum step wedge  

PubMed Central

Purpose ANSI/ADA has established standards for adequate radiopacity. This study was aimed to assess the changes in radiopacity of composite resins according to various tube-target distances and exposure times. Materials and Methods Five 1-mm thick samples of Filtek P60 and Clearfil composite resins were prepared and exposed with six tube-target distance/exposure time setups (i.e., 40 cm, 0.2 seconds; 30 cm, 0.2 seconds; 30 cm, 0.16 seconds, 30 cm, 0.12 seconds; 15 cm, 0.2 seconds; 15 cm, 0.12 seconds) performing at 70 kVp and 7 mA along with a 12-step aluminum stepwedge (1 mm incremental steps) using a PSP digital sensor. Thereafter, the radiopacities measured with Digora for Windows software 2.5 were converted to absorbencies (i.e., A=-log (1-G/255)), where A is the absorbency and G is the measured gray scale). Furthermore, the linear regression model of aluminum thickness and absorbency was developed and used to convert the radiopacity of dental materials to the equivalent aluminum thickness. In addition, all calculations were compared with those obtained from a modified 3-step stepwedge (i.e., using data for the 2nd, 5th, and 8th steps). Results The radiopacities of the composite resins differed significantly with various setups (p<0.001) and between the materials (p<0.001). The best predicted model was obtained for the 30 cm 0.2 seconds setup (R2=0.999). Data from the reduced modified stepwedge was remarkable and comparable with the 12-step stepwedge. Conclusion Within the limits of the present study, our findings support that various setups might influence the radiopacity of dental materials on digital radiographs.

Poorsattar Bejeh Mir, Morvarid

2012-01-01

217

Development of the short time exposure (STE) test: an in vitro eye irritation test using SIRC cells.  

PubMed

Using SIRC (rabbit corneal cell line) cells, we developed an alternative eye irritation test: the short time exposure (STE) test. This STE test is a cytotoxicity test using physiological saline or mineral oil as the test solvent. Evaluation exposure time is short (5 min), which is similar to actual exposure situations, and uses the cell viability (CV) at a constant concentration as the endpoint for irritation potential. First, in order to confirm the usefulness of this STE test in assessing eye irritation potential of chemicals, 51 raw materials were tested and the correlation between CV in the STE test and the eye irritation score in the Draize test was examined. For the undiluted raw materials tested in the Draize test, the 5% test concentration in the STE test gave irritation classes that correlated well with the irritation classes from the Draize test (accuracy: 89.6%). For those materials tested as a 10% solution in the Draize test, STE irritation classes with 0.05% test concentration corresponded well with the Draize irritation classes (accuracy: 80.0%). Next, using the cell viabilities at these two concentrations, the STE prediction model (PM) was developed. A score of 1 or 2 was given for the results from each tested concentration in the STE test and Draize test. The scores from each test were then summed to yield a 3-level (Rank 1: minimally irritant, Rank 2: moderate irritant, Rank 3: severe irritant) eye irritation potential classification. Rank classification in the STE test showed a good correlation mostly to that in the Draize test (irritation class correspondence rate: 70.2%, but after exclusion of data of alcoholic materials, the rate was 91.7%). In most cytotoxicity test, the cytotoxicity of acids and amines is generally underestimated due the use of medium as the solvent. This is the result of the buffering capacity of the media. On the other hand, the STE test could predict the eye irritation potential by evaluating the chemical with a 5% test concentration. Eleven water insoluble materials such as toluene, octanol, and hexanol could be evaluated by using mineral oil as test solvent in the STE test. The STE test demonstrated itself to be simple, promising, have great potential, be of value, and to be an easily standardized alternative eye irritation test. PMID:18248950

Takahashi, Yutaka; Koike, Mirei; Honda, Hiroshi; Ito, Yuichi; Sakaguchi, Hitoshi; Suzuki, Hiroyuki; Nishiyama, Naohiro

2008-04-01

218

Consequences of ethanol exposure on cued and contextual fear conditioning and extinction differ depending on timing of exposure during adolescence or adulthood.  

PubMed

Some evidence suggests that adolescents are more sensitive than adults to ethanol-induced cognitive deficits and that these effects may be long-lasting. The purpose of Exp 1 was to determine if early-mid adolescent [postnatal day (P) 28-48] intermittent ethanol exposure would affect later learning and memory in a Pavlovian fear conditioning paradigm differently than comparable exposures in adulthood (P70-90). In Exp 2 animals were exposed to ethanol during mid-late adolescence (P35-55) to assess whether age of initiation within the adolescent period would influence learning and memory differentially. Male Sprague-Dawley rats were given 4 g/kg i.g. ethanol (25%) or water every 48 h for a total of 11 exposures. After a 22 day non-ethanol period, animals were fear conditioned to a context (relatively hippocampal-dependent task) or tone (amygdala-dependent task), followed by retention tests and extinction (mPFC-dependent) of this conditioning. Despite similar acquisition, a deficit in context fear retention was evident in animals exposed to ethanol in early adolescence, an effect not observed after a comparable ethanol exposure in mid-late adolescence or adulthood. In contrast, animals that were exposed to ethanol in mid-late adolescence or adulthood showed enhanced resistance to context extinction. Together these findings suggest that repeated ethanol imparts long-lasting consequences on learning and memory, with outcomes that differ depending on age of exposure. These results may reflect differential influence of ethanol on the brain as it changes throughout ontogeny and may have implications for alcohol use not only throughout the developmental period of adolescence, but also in adulthood. PMID:23938333

Broadwater, Margaret; Spear, Linda P

2013-11-01

219

Time Course of Microbiologic Outcome and Gene Expression in Candida albicans during and following In Vitro and In Vivo Exposure to Fluconazole†  

PubMed Central

Pharmacodynamics (PD) considers the relationship between drug exposure and effect. The two factors that have been used to distinguish the PD behaviors of antimicrobials are the impact of concentration on the extent of organism killing and the duration of persistent microbiologic suppression (postantibiotic effect). The goals of these studies were (i) to examine the relationship between antimicrobial PD and gene expression and (ii) to gain insight into the mechanism of fluconazole effects persisting following exposure. Microarrays were used to?estimate the transcriptional response of Candida albicans to a supra-MIC F exposure over time in vitro. Fluconazole at four times the MIC was added to a log-phase C. albicans culture, and cells were collected to determine viable growth and for microarray analyses. We identified differential expression of 18% of all genes for at least one of the time points. More genes were upregulated (n = 1,053 [16%]) than downregulated (174 [3%]). Of genes with known function that were upregulated during exposure, most were related to plasma membrane/cell wall synthesis (18%), stress responses (7%), and metabolism (6%). The categories of downregulated genes during exposure included protein synthesis (15%), DNA synthesis/repair (7%), and transport (7%) genes. The majority of genes identified at the postexposure time points were from the protein (17%) and DNA (7%) synthesis categories. In subsequent studies, three genes (CDR1, CDR2, and ERG11) were examined in greater detail (more concentration and time points) following fluconazole exposure in vitro and in vivo. Expression levels from the in vitro and in vivo studies were congruent. CDR1 and CDR2 transcripts were reduced during in vitro fluconazole exposure and during supra-MIC exposure in vivo. However, in the postexposure period, the mRNA abundance of both pumps increased. ERG11 expression increased during exposure and fell in the postexposure period. The expression of the three genes responded in a dose-dependent manner. In sum, the microarray data obtained during and following fluconazole exposure identified genes both known and unknown to be affected by this drug class. The expanded in vitro and in vivo expression data set underscores the importance of considering the time course of exposure in pharmacogenomic investigations.

Lepak, A.; Nett, J.; Lincoln, L.; Marchillo, K.; Andes, D.

2006-01-01

220

The solar UV exposure time required for vitamin D3 synthesis in the human body estimated by numerical simulation and observation in Japan  

NASA Astrophysics Data System (ADS)

After the discovery of Antarctic ozone hole, the negative effect of exposure of human body to harmful solar ultraviolet (UV) radiation is widely known. However, there is positive effect of exposure to UV radiation, i.e., vitamin D synthesis. Although the importance of solar UV radiation for vitamin D3 synthesis in the human body is well known, the solar exposure time required to prevent vitamin D deficiency has not been well determined. This study attempted to identify the time of solar exposure required for vitamin D3 synthesis in the body by season, time of day, and geographic location (Sapporo, Tsukuba, and Naha, in Japan) using both numerical simulations and observations. According to the numerical simulation for Tsukuba at noon in July under a cloudless sky, 2.3 min of solar exposure are required to produce 5.5 ?g vitamin D3 per 600 cm2 skin. This quantity of vitamin D represents the recommended intake for an adult by the Ministry of Health, Labour and Welfare, and the 2010 Japanese Dietary Reference Intakes (DRIs). In contrast, it took 49.5 min to produce the same amount of vitamin D3 at Sapporo in the northern part of Japan in December, at noon under a cloudless sky. The necessary exposure time varied considerably with the time of the day. For Tsukuba at noon in December, 14.5 min were required, but at 09:00 68.7 min were required and at 15:00 175.8 min were required for the same meteorological conditions. Naha receives high levels of UV radiation allowing vitamin D3 synthesis almost throughout the year. According to our results, we are further developing an index to quantify the necessary time of UV radiation exposure to produce required amount of vitamin D3 from a UV radiation data.

Nakajima, Hideaki; Miyauchi, Masaatsu; Hirai, Chizuko

2013-04-01

221

Adult asthma and traffic exposure at residential address, workplace address, and self-reported daily time outdoor in traffic: A two-stage case-control study  

PubMed Central

Background Most epidemiologic studies use traffic at residential address as a surrogate for total traffic exposure when investigating effects of traffic on respiratory health. This study used GIS (Geographical Information Systems) to estimate traffic exposure, not only on residential, but also on workplace address, in addition to survey questions on time spent in traffic during commuting or other daily activities. The aim was to investigate 1) if there is an association between traffic exposure and prevalence of adult asthma and asthma symptoms, and 2) if so, does this association become stronger using more complete traffic exposure information. Methods This study was conducted in two stages: A first cross-sectional survey in Southern Sweden 2004 (n = 24819, 18-80 years, response rate 59%) was followed by a case-control study in 2005 to obtain more detailed exposure and confounder information (n = 2856, asthmatics and controls (1:3), 86% response rate). In the first survey, only residential address was known. In the second survey, questions about workplace addresses and daily time spent in traffic were also included. Residential and workplace addresses were geocoded and linked with GIS to road data and dispersion modelled outdoor concentrations of NOx (annual mean, 250 × 250 m resolution). Results Living within 50 m of a road (measured by GIS) with traffic intensity of >10 cars/minute (compared with no road within this distance) was associated with an increased prevalence of asthma, (OR = 1.8, 95% CI = (1.1-2.8), and with asthma symptoms last 12 months. No statistically significant effects were seen for traffic exposure at workplace address, daily time spent in traffic, or commuting time to work, after adjustment for confounders. A combined total exposure estimate did not give a stronger association with asthma prevalence or asthma symptoms. Conclusions Traffic exposure at close proximity to residential address showed association with asthma prevalence and asthma symptoms last 12 months, among adults in southern Sweden. The associations were not stronger when accounting for total traffic exposure. This could reflect exposure misclassfication at workplace address and for other daily time in traffic, but also that residential address remains the main determinant for traffic exposure among adults.

2010-01-01

222

A quantitative comparison of mechanical blood damage parameters in rotary ventricular assist devices: shear stress, exposure time and hemolysis index.  

PubMed

Ventricular assist devices (VADs) have already helped many patients with heart failure but have the potential to assist more patients if current problems with blood damage (hemolysis, platelet activation, thrombosis and emboli, and destruction of the von Willebrand factor (vWf)) can be eliminated. A step towards this goal is better understanding of the relationships between shear stress, exposure time, and blood damage and, from there, the development of numerical models for the different types of blood damage to enable the design of improved VADs. In this study, computational fluid dynamics (CFD) was used to calculate the hemodynamics in three clinical VADs and two investigational VADs and the shear stress, residence time, and hemolysis were investigated. A new scalar transport model for hemolysis was developed. The results were compared with in vitro measurements of the pressure head in each VAD and the hemolysis index in two VADs. A comparative analysis of the blood damage related fluid dynamic parameters and hemolysis index was performed among the VADs. Compared to the centrifugal VADs, the axial VADs had: higher mean scalar shear stress (sss); a wider range of sss, with larger maxima and larger percentage volumes at both low and high sss; and longer residence times at very high sss. The hemolysis predictions were in agreement with the experiments and showed that the axial VADs had a higher hemolysis index. The increased hemolysis in axial VADs compared to centrifugal VADs is a direct result of their higher shear stresses and longer residence times. Since platelet activation and destruction of the vWf also require high shear stresses, the flow conditions inside axial VADs are likely to result in more of these types of blood damage compared with centrifugal VADs. PMID:22938355

Fraser, Katharine H; Zhang, Tao; Taskin, M Ertan; Griffith, Bartley P; Wu, Zhongjun J

2012-08-01

223

Limitations Placed on the Time Coverage, Isoplanatic Patch Size and Exposure Time for Solar Observations Using Image Selection Procedures in the Presence of Telescope Aberrations  

NASA Astrophysics Data System (ADS)

Image selection, adaptive optics and post-facto image restoration methods are all techniques being used for diffraction limited imaging with ground-based solar and stellar telescopes. Often these techniques are used in a hybrid form like e.g. the application of adaptive optics and/or post-facto image restoration in combination with already good images obtained by image selection in periods of good seeing. Fried (JOSA 56, 1372, 1966), Hecquet and Coupinot (J. Optics/Paris 16, 21, 1985) and Beckers ("Solar and Stellar Granulation", Kluwer, Rutten & Severino Eds, 55, 1988) already discussed the usefulness of image selection, or the "Lucky Observer" mode, for high resolution imaging. All assumed perfect telescope optics. In case of moderate telescope aberrations image selection can still lead to diffraction limited imaging but only when the atmospheric wavefront aberration happens to compensate that of the telescope. In this "Very Lucky Observer" mode the probability of obtaining a good image is reduced over the un-aberrated case, as are the size of the isoplanatic patch and the exposure time. We describe an analysis of these effects for varying telescope aberrations. These result in a strong case for the removal of telescope aberrations either by initial implementation or by the use of slow active optics.

Beckers, J. M.; Rimmele, T. R.

1996-12-01

224

Correlation between pulsed electromagnetic fields exposure time and cell proliferation increase in human osteosarcoma cell lines and human normal osteoblast cells in vitro.  

PubMed

We have exposed cultured bone cells to a pulsed electromagnetic field (PEMF) for different times to find the minimal exposure time necessary to stimulate an increase of DNA synthesis. We used two different human osteosarcoma cell lines, TE-85 and MG-63, and human normal osteoblast cell (NHOC) obtained from surgical bone specimens. The cells were placed in multiwell plates and set in a tissue culture incubator between a pair of Helmoltz coils powered by a pulse generator (1.3-ms pulse, repeated at 75 Hz) for different periods of time. [3H]Thymidine incorporation was used to evaluate cell proliferation. The two osteosarcoma cell lines increase their thymidine incorporation when exposed to a PEMF for at least 30 min, both in a medium containing 10% fetal calf serum and in a serum-free medium. NHOC are known to increase their cell proliferation when exposed to PEMF but only if cultured in the presence of 10% fetal calf serum. In this experimental condition, three of the four cell lineages studied required at least 9 h of PEMF exposure to increase their DNA synthesis, whereas one cell lineage increased its cell proliferation after 6 h of PEMF exposure. Our observations confirm the hypothesis that the proliferative responses of NHOC and human osteosarcoma cell lines to PEMF exposure are quite different. Moreover, NHOC required minimal exposure times to PEMF to increase their cell proliferation, similar to that needed to stimulate bone formation in vivo. PMID:10194560

De Mattei, M; Caruso, A; Traina, G C; Pezzetti, F; Baroni, T; Sollazzo, V

1999-01-01

225

Using Global Positioning Systems (GPS) and temperature data to generate time-activity classifications for estimating personal exposure in air monitoring studies: an automated method  

PubMed Central

Background Personal exposure studies of air pollution generally use self-reported diaries to capture individuals’ time-activity data. Enhancements in the accuracy, size, memory and battery life of personal Global Positioning Systems (GPS) units have allowed for higher resolution tracking of study participants’ locations. Improved time-activity classifications combined with personal continuous air pollution sampling can improve assessments of location-related air pollution exposures for health studies. Methods Data was collected using a GPS and personal temperature from 54 children with asthma living in Montreal, Canada, who participated in a 10-day personal air pollution exposure study. A method was developed that incorporated personal temperature data and then matched a participant’s position against available spatial data (i.e., road networks) to generate time-activity categories. The diary-based and GPS-generated time-activity categories were compared and combined with continuous personal PM2.5 data to assess the impact of exposure misclassification when using diary-based methods. Results There was good agreement between the automated method and the diary method; however, the automated method (means: outdoors?=?5.1%, indoors other =9.8%) estimated less time spent in some locations compared to the diary method (outdoors?=?6.7%, indoors other?=?14.4%). Agreement statistics (AC1?=?0.778) suggest ‘good’ agreement between methods over all location categories. However, location categories (Outdoors and Transit) where less time is spent show greater disagreement: e.g., mean time “Indoors Other” using the time-activity diary was 14.4% compared to 9.8% using the automated method. While mean daily time “In Transit” was relatively consistent between the methods, the mean daily exposure to PM2.5 while “In Transit” was 15.9 ?g/m3 using the automated method compared to 6.8 ?g/m3 using the daily diary. Conclusions Mean times spent in different locations as categorized by a GPS-based method were comparable to those from a time-activity diary, but there were differences in estimates of exposure to PM2.5 from the two methods. An automated GPS-based time-activity method will reduce participant burden, potentially providing more accurate and unbiased assessments of location. Combined with continuous air measurements, the higher resolution GPS data could present a different and more accurate picture of personal exposures to air pollution.

2014-01-01

226

An examination of the time course from human dietary exposure to polycyclic aromatic hydrocarbons to urinary elimination of 1-hydroxypyrene.  

PubMed Central

The significance of diet as an exposure route for polycyclic aromatic hydrocarbons (PAHs) and the associated kinetics of urinary 1-hydroxypyrene (1-OHPY) elimination were examined through a controlled human exposure study. Results showed that a 100 to 250-fold increase in a dietary benzo(a)pyrene (BaP) dose paralleled a four to 12-fold increase in urinary 1-OHPy elimination. Mean elimination rates during minimal exposure periods ranged from 6 to 17 ng/h whereas peak elimination rates of 60 to 189 ng/h were seen after a meal high in PAHs. A biexponential model fitted to a limited number of urinary 1-OHPY elimination points gave mean kinetic parameter estimates for t1/2 of 4.4 hours and tmax of 6.3 hours. It is concluded that dietary exposure to PAHs is potentially as substantial as some occupational exposures and therefore requires consideration in studies of exposure to PAHs. The dietary control strategies and the kinetic parameters defined in this investigation provide data for the control of this exposure route when examining other sources of exposure.

Buckley, T J; Lioy, P J

1992-01-01

227

Time trends in exposure to environmental tobacco smoke and parental educational level for 6-year-old children in Germany  

Microsoft Academic Search

The aim of the study was to investigate the association between exposure to environmental tobacco smoke of 6-year-old children and parental educational level in Germany under the changing socioeconomic conditions after reunification. Logistic regression was used to examine the relationship between tobacco smoke exposure of children (current environmental tobacco smoke, maternal smoking during pregnancy, environmental tobacco smoke during the first

Xianming du Prel; Ursula Krämer; Ulrich Ranft

2006-01-01

228

Homologous Recombination is Activated at Early Time Points Following Exposure to Cobalt Chloride Induced Hypoxic Conditions in Saccharomyces cerevisiae.  

PubMed

DNA repair functions are essential for the maintenance of genetic integrity and are regulated in response to both environmental and chemical stressors in mammalian and yeast cells in culture. The inhibitory effect of limited O2 availability on DNA repair functions in general and on homologous recombination (HR) in particular, correlates with increased chromosomal abnormalities in hypoxic cancer cells. Given the above, we have investigated the effects of CoCl2,--a hypoxia mimetic agent on HR and genetic aberrations in Saccharomyces cerevisiae. Our studies demonstrate that both acute and chronic exposure to CoCl2 activated HR and increased genetic aberrations in S. cerevisiae D7 cells. At early time points following addition of CoCl2 to the growth media, cells were briefly arrested in the G1-S boundary concomitant with a transient increase in Rad52-GFP foci formation and induction of low levels of DNA damage. The mode of action of CoCl2 is thus similar to that of DNA synthesis inhibitors, the later are known to induce HR and cause G1-S arrest. We propose that the activation of HR in the presence of the hypoxia mimetic agent may be attributed to the replication stress and/or DNA damage induced by the stressor. PMID:23729884

Meena, Ramesh Chand; Kumar, Navin; Nath, Surendra; Chakrabarti, Amitabha

2012-06-01

229

Patterns and timing of sunlight exposure and risk of basal cell and squamous cell carcinomas of the skin - a case-control study  

PubMed Central

Background Non-melanoma skin cancer (NMSC), comprised of basal (BCC) and squamous (SCC) cell carcinomas, is the most common cancer in Caucasians. Ultraviolet radiation (UVR) exposure is the most important environmental risk factor for NMSC. However, the precise relationship between UVR and the risk of NMSC is complex, and the relationship may differ by skin cancer type. Methods A case–control study was conducted among Florida residents to investigate measures of patterns (intermittent vs. continuous) and timing (childhood vs. adulthood) of sunlight exposure in BCC and SCC. Participants included 218 BCC and 169 SCC cases recruited from a university dermatology clinic and 316 controls with no history of skin or other cancers. Results A history of blistering sunburn (a measure of intermittent sunlight exposure) was associated with both BCC (OR?=?1.96, 95% CI?=?1.27-3.03) and SCC (OR?=?2.02, 95% CI?=?1.22-3.33). Additionally, having a job in the sun for ?3 months for 10 years or longer (a measure of continuous sunlight exposure) was also associated with both BCC and SCC in our study population. With the exception of younger age at first blistering sunburn, measures of younger age at sunlight exposure tended to be associated with SCC, but not BCC risk. Conclusions Results from the current study suggest that sunlight exposure is associated with both BCC and SCC risk regardless of the pattern in which the exposure was received (i.e. intermittent vs. continuous). The data also suggest that sunlight exposure at a younger age may be more important for SCC but not BCC, however additional studies are needed to further characterize sunlight exposure-response relationships in different types of NMSC.

2012-01-01

230

A Wide-Dynamic-Range CMOS Image Sensor Based on Multiple Short Exposure-Time Readout With Multiple-Resolution Column-Parallel ADC  

Microsoft Academic Search

A wide-dynamic-range CMOS image sensor based on synthesis of one long and multiple short exposure-time signals is proposed. A high-speed, high-resolution column-parallel integration type analog-to-digital converter (ADC) with a nonlinear slope is crucial for this purpose. A prototype wide-dynamic-range CMOS image sensor that captures one long and three short exposure-time signals has been developed using 0.25-mum 1-poly 4-metal CMOS image

Masaaki Sasaki; Mitsuhito Mase; Shoji Kawahito; Yoshiaki Tadokoro

2007-01-01

231

The Eect of Exposure Time to Clean Room Air on Characteristic Parameters of Au /Epilayer n-Si Schottky Diodes  

NASA Astrophysics Data System (ADS)

A study has been made on determination and comparison of current-voltage (I-V) and capacitance-voltage (C-V) characteristics parameters of Au/n-Si Schottky barrier diodes (SBDs) with and without thin native oxide layer fabricated on n-type Si grown by LPE (Liquid-phase Epitaxy) technique. The native oxide layer with different thicknesses on chemically cleaned on Si surface were obtained by exposing the surfaces to clean room air before evaporating metal. The native oxide thicknesses of samples D2, D3, D4 and D5 are in the form D2 < D3 < D4 ? D5, depending on the exposing time. It has been seen that the values of barrier height Fb of samples D2(0.64 eV), D3(0.66 eV), D4(0.69 eV) and D5(0.69 eV) with the interfacial layer increased with increasing the exposure time and tended to that of the initial sample D1 (nonoxidezed sample, 0.74 eV), and thus also their I-V and C-V curves. The reverse current of sample D1 showed slight nonsaturating behavior. This ''soft'' behavior has been ascribed to the spatial inhomogeneity in the barrier heights at the MS interface. In particular, reverse bias curves of samples D2, D3, D4 and D5 have shown excellent saturation which may be attributed to the passivation of the semiconductor surface states by the native oxide layer which reduces the penetration of the wave functions of electron in the metal into the semiconductor. Especially, the I-V characteristics and experimental parameters of our devices are in agreement with recently reported results revealed by the pulsed surface photovoltage technique for the electronic properties of the HF-treated Si surface during initial oxidation in air.

Saðlam, M.; Nuhoðlu, Ç.; Ayyildiz, E.; Türüt, A.; Çetýnkara, H. A.

1998-05-01

232

Arginine supplementation and exposure time affects polyamine and glucose metabolism in primary liver cells isolated from Atlantic salmon.  

PubMed

Arginine has been demonstrated to enhance glucose and lipid oxidation in mammals through activation of polyamine turnover. We aimed to investigate how arginine affects energy utilization through polyamine metabolism and whether this effect is time dependent. Primary liver cells were isolated from Atlantic salmon (2.2 kg body weight) fed diets containing 25.5 (low arginine, LA) or 36.1 (high arginine, HA) g arginine/kg dry matter for 12 weeks, to investigate the effect of long-term arginine supplementation. The cells were cultured for 24 h in L-15 medium to which either alpha-difluoromethylornithine (DFMO) or N (1),N (11)-diethylnorspermine (DENSPM) was added. Analysis of the medium by nuclear magnetic resonance revealed significant differences between the two dietary groups as well as between cells exposed to DFMO and DENSPM, with decreased glucose, fumarate and lactate concentrations in media of the HA cells. Liver cells from fish fed the HA diet had higher spermidine/spermine-N1-acetyltransferase protein abundance and lower adenosine triphosphate concentration as compared to the LA-fed fish, while gene expression was not affected by either diet or treatment. Primary liver cells isolated from salmon fed a commercial diet and cultured in L-15 media with or without arginine supplementation (1.82 or 3.63 mM) for 48 h, representing short-term effect of arginine supplementation, showed differential expression of genes for apoptosis and polyamine synthesis due to arginine supplementation or inhibition by DFMO. Overall, arginine concentration and exposure time affected energy metabolism and gene regulation more than inhibition or activation of key enzymes of polyamine metabolism, suggesting a polyamine-independent influence of arginine on cellular energy metabolism and survival. PMID:24500114

Andersen, Synne Marte; Taylor, Richard; Holen, Elisabeth; Aksnes, Anders; Espe, Marit

2014-05-01

233

The impact of missing data on analyses of a time-dependent exposure in a longitudinal cohort: a simulation study  

PubMed Central

Background Missing data often cause problems in longitudinal cohort studies with repeated follow-up waves. Research in this area has focussed on analyses with missing data in repeated measures of the outcome, from which participants with missing exposure data are typically excluded. We performed a simulation study to compare complete-case analysis with Multiple imputation (MI) for dealing with missing data in an analysis of the association of waist circumference, measured at two waves, and the risk of colorectal cancer (a completely observed outcome). Methods We generated 1,000 datasets of 41,476 individuals with values of waist circumference at waves 1 and 2 and times to the events of colorectal cancer and death to resemble the distributions of the data from the Melbourne Collaborative Cohort Study. Three proportions of missing data (15, 30 and 50%) were imposed on waist circumference at wave 2 using three missing data mechanisms: Missing Completely at Random (MCAR), and a realistic and a more extreme covariate-dependent Missing at Random (MAR) scenarios. We assessed the impact of missing data on two epidemiological analyses: 1) the association between change in waist circumference between waves 1 and 2 and the risk of colorectal cancer, adjusted for waist circumference at wave 1; and 2) the association between waist circumference at wave 2 and the risk of colorectal cancer, not adjusted for waist circumference at wave 1. Results We observed very little bias for complete-case analysis or MI under all missing data scenarios, and the resulting coverage of interval estimates was near the nominal 95% level. MI showed gains in precision when waist circumference was included as a strong auxiliary variable in the imputation model. Conclusions This simulation study, based on data from a longitudinal cohort study, demonstrates that there is little gain in performing MI compared to a complete-case analysis in the presence of up to 50% missing data for the exposure of interest when the data are MCAR, or missing dependent on covariates. MI will result in some gain in precision if a strong auxiliary variable that is not in the analysis model is included in the imputation model.

2013-01-01

234

Estimation of safe exposure time from an ophthalmic operating microscope with regard to ultraviolet radiation and blue-light hazards to the eye  

NASA Astrophysics Data System (ADS)

Hazards from the optical radiation of an operating microscope that cause damage at the corneal, lenticular, and retinal levels were investigated; we considered, in particular, ultraviolet radiation (UVR) and blue light. The spectral irradiance from a Zeiss operation microscope OPMI VISU 200 was measured in the corneal plane between 300 and 1100 nm. Effective irradiance and radiance were calculated with relative spectral effectiveness data from the American Conference for Governmental and Industrial Hygienists. Safe exposure time to avoid UVR injury to the lens and cornea was found to be 2 h without a filter, 4 h with a UVR filter, 200 h with a yellow filter, and 400 h with a filter combination. Safe exposure time to avoid retinal photochemical injury was found to be 3 min without a filter and with a UVR filter, 10 min with a yellow filter, and 49 min with a filter combination. The effective radiance limit for retinal thermal injury was not exceeded. The hazard due to the UVR component from the operating microscope is not critical, and operation time can be safely prolonged with the use of appropriate filters. The retinal photochemical hazard appears critical without appropriate filters, permitting only some minutes of safe exposure time. The calculated safe exposure times are for worst-case conditions and maximal light output and include a safety factor.

Michael, Ralph; Wegener, Alfred

2004-08-01

235

GPS-based microenvironment tracker (MicroTrac) model to estimate time-location of individuals for air pollution exposure assessments: Model evaluation in central North Carolina.  

PubMed

A critical aspect of air pollution exposure assessment is the estimation of the time spent by individuals in various microenvironments (ME). Accounting for the time spent in different ME with different pollutant concentrations can reduce exposure misclassifications, while failure to do so can add uncertainty and bias to risk estimates. In this study, a classification model, called MicroTrac, was developed to estimate time of day and duration spent in eight ME (indoors and outdoors at home, work, school; inside vehicles; other locations) from global positioning system (GPS) data and geocoded building boundaries. Based on a panel study, MicroTrac estimates were compared with 24-h diary data from nine participants, with corresponding GPS data and building boundaries of home, school, and work. MicroTrac correctly classified the ME for 99.5% of the daily time spent by the participants. The capability of MicroTrac could help to reduce the time-location uncertainty in air pollution exposure models and exposure metrics for individuals in health studies. PMID:24619294

Breen, Michael S; Long, Thomas C; Schultz, Bradley D; Crooks, James; Breen, Miyuki; Langstaff, John E; Isaacs, Kristin K; Tan, Yu-Mei; Williams, Ronald W; Cao, Ye; Geller, Andrew M; Devlin, Robert B; Batterman, Stuart A; Buckley, Timothy J

2014-07-01

236

ADAPTATION OF NATURAL MICROBIAL MMUNITIES TO DEGRADATION OF XENOBIOTIC COMPOUNDS: EFFECTS OF CONCENTRATION, EXPOSURE TIME, INOCULUM, AND CHEMICAL STRUCTURE  

EPA Science Inventory

Adaptation of microbial populations to degrade xenobiotic compounds faster after exposure to the compound was studied in eco-cores. Radiolabeled test compounds were added to cores that contained natural water and sediment samples. Adaptation was detected by comparing mineralizati...

237

Timed Maternal Melatonin Treatment Reverses Circadian Disruption of the Fetal Adrenal Clock Imposed by Exposure to Constant Light  

PubMed Central

Surprisingly, in our modern 24/7 society, there is scant information on the impact of developmental chronodisruption like the one experienced by shift worker pregnant women on fetal and postnatal physiology. There are important differences between the maternal and fetal circadian systems; for instance, the suprachiasmatic nucleus is the master clock in the mother but not in the fetus. Despite this, several tissues/organs display circadian oscillations in the fetus. Our hypothesis is that the maternal plasma melatonin rhythm drives the fetal circadian system, which in turn relies this information to other fetal tissues through corticosterone rhythmic signaling. The present data show that suppression of the maternal plasma melatonin circadian rhythm, secondary to exposure of pregnant rats to constant light along the second half of gestation, had several effects on fetal development. First, it induced intrauterine growth retardation. Second, in the fetal adrenal in vivo it markedly affected the mRNA expression level of clock genes and clock-controlled genes as well as it lowered the content and precluded the rhythm of corticosterone. Third, an altered in vitro fetal adrenal response to ACTH of both, corticosterone production and relative expression of clock genes and steroidogenic genes was observed. All these changes were reversed when the mother received a daily dose of melatonin during the subjective night; supporting a role of melatonin on overall fetal development and pointing to it as a ‘time giver’ for the fetal adrenal gland. Thus, the present results collectively support that the maternal circadian rhythm of melatonin is a key signal for the generation and/or synchronization of the circadian rhythms in the fetal adrenal gland. In turn, low levels and lack of a circadian rhythm of fetal corticosterone may be responsible of fetal growth restriction; potentially inducing long term effects in the offspring, possibility that warrants further research.

Mendez, Natalia; Abarzua-Catalan, Lorena; Vilches, Nelson; Galdames, Hugo A.; Spichiger, Carlos; Richter, Hans G.; Valenzuela, Guillermo J.; Seron-Ferre, Maria; Torres-Farfan, Claudia

2012-01-01

238

Effect of moisture content, temperature and exposure time on the physical stability of chitosan powder and tablets.  

PubMed

Abstract Context: Chitosan does not rank highly regarding its employment as tablet filler due to certain limitations. Undesirable properties that limit its utilization as excipient in solid dosage forms include its hydration propensity that negatively affects tablet stability, strength and disintegration. Objective: The objective of this study was to investigate the physical stability of chitosan powder, mixtures, granules and tablets under accelerated conditions such as elevated temperatures and humidity over different periods of time. Methods: Selected physico-chemical properties of pure chitosan powder, physical mixtures of chitosan with Kollidon® VA64 (BASF, Ludwigshafen, Germany), chitosan granules, as well as tablets were evaluated under conditions of elevated humidity and temperature. Results and discussion: The physical stability of chitosan tablets exhibited sensitivity towards varying exposure conditions. It was furthermore evident that the presence of moisture (sorbed water) had a marked influence on the physical stability of chitosan powder and tablets. It was evident that the presence of Kollidon® VA64 as well as the method of inclusion of this binder influenced the properties of chitosan tablets. The physical stability of chitosan powder deteriorated to a greater extent compared to that of the chitosan tablets, which were subjected to the same conditions. Conclusion: It is recommended that tablets containing chitosan should be stored at a temperature not exceeding 25?°C as well as at a relatively low humidity (<60%) to prevent deterioration of physical properties. Direct compression of chitosan granules which contained 5%w/w Kollidon® VA64 produced the best formulation in terms of physical stability at the different conditions. PMID:23596972

Viljoen, Joe M; Steenekamp, Jan H; Marais, Andries F; Kotzé, Awie F

2014-06-01

239

Radiation metabolomics. 2. Dose- and time-dependent urinary excretion of deaminated purines and pyrimidines after sublethal gamma-radiation exposure in mice.  

PubMed

Gamma-radiation exposure of humans is a major public health concern as the threat of terrorism and potential hostile use of radiological devices increases worldwide. We report here the effects of sublethal gamma-radiation exposure on the mouse urinary metabolome determined using ultra-performance liquid chromatography-coupled time-of-flight mass spectrometry-based metabolomics. Five urinary biomarkers of sublethal radiation exposure that were statistically significantly elevated during the first 24 h after exposure to doses ranging from 1 to 3 Gy were unequivocally identified by tandem mass spectrometry. These are deaminated purine and pyrimidine derivatives, namely, thymidine, 2'-deoxyuridine, 2'-deoxyxanthosine, xanthine and xanthosine. Furthermore, the aminopyrimidine 2'-deoxycytidine appeared to display reduced urinary excretion at 2 and 3 Gy. The elevated biomarkers displayed a time-dependent excretion, peaking in urine at 8-12 h but returning to baseline by 36 h after exposure. It is proposed that 2'-deoxyuridine and 2'-deoxyxanthosine arise as a result of gamma irradiation by nitrosative deamination of 2'-deoxycytidine and 2'-deoxyguanosine, respectively, and that this further leads to increased synthesis of thymidine, xanthine and xanthosine. The urinary excretion of deaminated purines and pyrimidines, at the expense of aminopurines and aminopyrimidines, appears to form the core of the urinary radiation metabolomic signature of mice exposed to sublethal doses of ionizing radiation. PMID:19580506

Tyburski, John B; Patterson, Andrew D; Krausz, Kristopher W; Slavík, Josef; Fornace, Albert J; Gonzalez, Frank J; Idle, Jeffrey R

2009-07-01

240

Radiation Metabolomics. 2. Dose- and Time-Dependent Urinary Excretion of Deaminated Purines and Pyrimidines after Sublethal Gamma-Radiation Exposure in Mice  

PubMed Central

Gamma-radiation exposure of humans is a major public health concern as the threat of terrorism and potential hostile use of radiological devices increases worldwide. We report here the effects of sublethal ?-radiation exposure on the mouse urinary metabolome determined using ultra-performance liquid chromatography-coupled time-of-flight mass spectrometry-based metabolomics. Five urinary biomarkers of sublethal radiation exposure that were statistically significantly elevated during the first 24 h after exposure to doses ranging from 1 to 3 Gy were unequivocally identified by tandem mass spectrometry. These are deaminated purine and pyrimidine derivatives, namely, thymidine, 2?-deoxyuridine, 2?-deoxyxanthosine, xanthine and xanthosine. Furthermore, the aminopyrimidine 2?-deoxycytidine appeared to display reduced urinary excretion at 2 and 3 Gy. The elevated biomarkers displayed a time-dependent excretion, peaking in urine at 8–12 h but returning to baseline by 36 h after exposure. It is proposed that 2?-deoxyuridine and 2?-deoxyxanthosine arise as a result of ? irradiation by nitrosative deamination of 2?-deoxycytidine and 2?-deoxyguanosine, respectively, and that this further leads to increased synthesis of thymidine, xanthine and xanthosine. The urinary excretion of deaminated purines and pyrimidines, at the expense of aminopurines and aminopyrimidines, appears to form the core of the urinary radiation metabolomic signature of mice exposed to sublethal doses of ionizing radiation.

Tyburski, John B.; Patterson, Andrew D.; Krausz, Kristopher W.; Slavik, Josef; Fornace, Albert J.; Gonzalez, Frank J.; Idle, Jeffrey R.

2009-01-01

241

Antimycobacterial agents differ with respect to their bacteriostatic versus bactericidal activities in relation to time of exposure, mycobacterial growth phase, and their use in combination  

Microsoft Academic Search

A number of antimycobacterial agents were evaluated with respect to their bacteriostatic activity (growth inhibition) versus the bactericidal activity against a clinical isolate of Mycobacterium avium (Mycobacterium avium complex [MAC] strain 101) in relation to the time of exposure and the growth phase of the mycobacteria. In terms of growth inhibition the MAC in the active phase of growth was

Irma A. J. M. Bakker-Woudenberg; Wim van Vianen; Dick van Soolingen; Henri A. Verbrugh; Agtmael van M. A

2005-01-01

242

Effects of Prolonged Light Exposure Times on Water Sorption, Solubility and Cross-linking Density of Simplified Etch-and-Rinse Adhesives.  

PubMed

Purpose: This study evaluated the effects of light exposure times on water sorption, solubility, and polymer cross-linking density of simplified etch-and-rinse adhesives. Materials and Methods: Four commercial adhesives (XP Bond, Adper Single Bond 2, Tetric N-Bond, and Ambar) were selected, and resin disks 5 mm in diameter and 1.0 mm thick were prepared and light cured for 20, 40, or 80 s using an LED light-curing unit at 1200 mW/cm2. Water sorption and solubility were evaluated over a 28-day period. For polymer cross-linking density, additional specimens were prepared and their Knoop hardness measured before and after immersion in 100% ethanol. The data from each test were evaluated using a two-way ANOVA and Tukey's test (? = 0.05). Results: The XP Bond adhesive showed higher water sorption (similar to Adper Single Bond 2) and solubility (p < 0.05) than did the other materials. Prolonged exposure times did not reduce the water sorption but did reduce the solubility of all tested materials (p < 0.05). For Ambar, the increase in the exposure time resulted in a significantly lower percent reduction in hardness. Conclusion: Water sorption, solubility, and cross-linking density of the materials selected in this study seem to be mainly influenced by the adhesive composition. Prolonged light exposure times reduced the solubility of the materials. PMID:24847490

Wambier, Letícia; Malaquias, Tamirez; Wambier, Denise Stadler; Patzlaff, Rafael T; Bauer, José; Loguercio, Alessandro D; Reis, Alessandra

2014-06-01

243

Development of the murine and human immune system: differential effects of immunotoxicants depend on time of exposure.  

PubMed Central

Fetal and early postnatal life represent critical periods in vertebrate immune system development. Disruption of such development by perinatal immunotoxic chemical exposure has been widely described in experimental animal models. The resultant inhibited postnatal immune responses in such animals are often more dramatic and persistent than those after exposure during adult life. Further, recent reports suggest that prenatal exposure to immunotoxicants may exacerbate postnatal aberrant immune responses (e.g., hypersensitivity disorders and autoimmune disease) in genetically predisposed rodents. Limited information is available regarding the possibility of inhibited postnatal immune capacity in humans as a result of developmental immunotoxicant exposure. The multifactorial nature of hypersensitivity and autoimmune responses will further complicate the elucidation of possible relationships between chemical exposure during ontogeny of the human immune system and immune-mediated disease later in life. Taken together, however, the available animal data suggest the potential for altered postnatal immune function in humans exposed to immunotoxicants (e.g., environmental chemicals and therapeutic agents) during fetal and/or early postnatal life.

Holladay, S D; Smialowicz, R J

2000-01-01

244

Timing of prenatal maternal exposure to severe life events and adverse pregnancy outcomes: A population study of 2.6 million pregnancies  

PubMed Central

Objective To identify the impact of timing of prenatal stress exposure on offspring risk for shortened gestational age (GA), preterm birth (PTB), low birth weight (LBW), and small for gestational age (SGA) using a population-based sample. Methods Swedish longitudinal population registries were linked to study all individuals born in Sweden 1973–2004. Prenatal maternal stress exposure was defined as death of the father of the child or first degree relative of the mother. Using linear and logistic regression, timing of stress exposure was examined across pregnancy, by month, and by novel periods created based on month of stress exposure findings. Results A total of 2,618,777 live-born, singleton infants without congenital anomalies were included; 32,286 exposed to prenatal maternal stress. Examining associations between stress exposure and outcome by the month revealed that risk increases mid-gestation, particularly following months 5 and 6. Combining months 1–4, 5 and 6, and 7–9 as potential periods of differing vulnerability, it was found that stress during period 2 (months 5 and 6) was associated with the greatest risk for shortened GA (?0.52 days, SE=0.15, p=0.0006), PTB (OR=1.24, 99% CI=1.08–1.42), LBW (OR=1.38, 99% CI=1.19–1.61), and SGA (OR=1.25, 99% CI=1.05–1.49). Conclusions Risk for shortened GA, PTB, LBW, and SGA are greater following stress exposure during the 5th and/or 6th month of pregnancy. It may be beneficial to refine future analyses to these months. Possible mechanisms include alterations in the hypothalamic-pituitary-adrenal axis and associated stress-responsive molecular regulators.

Class, Quetzal A.; Lichtenstein, Paul; Langstrom, Niklas; D'Onofrio, Brian M.

2011-01-01

245

Predicting Changes in PM Exposure Over Time at U.S. Trucking Terminals Using Structural Equation Modeling Techniques  

PubMed Central

This study analyzes the temporal variability of occupational and environmental exposures to fine particulate matter in the U.S. trucking industry and tests the predictive ability of a novel multilayer statistical approach to occupational exposure modeling using structural equation modeling (SEM) techniques. For these purposes, elemental carbon mass in PM<1 µm at six U.S. trucking terminals were measured twice during the same season up to 2 years apart, observing concentrations in the indoor loading dock (median EC: period 1 = 0.65 µg/m3; period 2 = 0.94 µg/m3 ) and outdoor background location (median EC: period 1 = 0.46 µg/m3 ; period 2 = 0.67 µg/m3 ), as well as in the truck cabs of local drivers while on the road (median EC: period 1=1.09 µg/m3 ; period 2 = 1.07 µg/m3 ). There was a general trend toward higher exposures during the second sampling trips; however, these differences were statistically significant in only a few cases and were largely attributable to changes in weather patterns (wind speed, precipitation, etc.). Once accounting for systematic prediction errors in background concentrations, the SEM approach provided a strong fit for work-related exposures in this occupational setting.

Davis, Mary E.; Laden, Francine; Hart, Jaime E.; Garshick, Eric; Blicharz, Andrew; Smith, Thomas J.

2009-01-01

246

Sick building syndrome (SBS) and exposure to water-damaged buildings: Time series study, clinical trial and mechanisms  

Microsoft Academic Search

Occupants of water-damaged buildings (WDBs) with evidence of microbial amplification often describe a syndrome involving multiple organ systems, commonly referred to as “sick building syndrome” (SBS), following chronic exposure to the indoor air. Studies have demonstrated that the indoor air of WDBs often contains a complex mixture of fungi, mycotoxins, bacteria, endotoxins, antigens, lipopolysaccharides, and biologically produced volatile compounds. A

Ritchie C. Shoemaker; Dennis E. House

2006-01-01

247

Effect of Exposure Time At 250F ON Stress-Corrosion Crack Growth Rates in 2024-T351 Aluminum.  

National Technical Information Service (NTIS)

The sensitization of 2024-T351 to stress-corrosion cracking after exposure at 250F has been measured using precracked double cantilever beam (DCB) specimens taken in the short-transverse grain direction from 1-in.-thick plate. The susceptibility of the ma...

M. V. Hyatt W. E. Quist

1970-01-01

248

Prenatal Exposure to Nicotine Impairs Performance of the 5Choice Serial Reaction Time Task in Adult Rats  

Microsoft Academic Search

Cigarette smoking is associated with a wide variety of adverse reproductive outcomes, including increased infant mortality and decreased birth weight. Prenatal exposure to tobacco smoke, of which nicotine is a major teratogenic component, has also been linked to the acceleration of the risk for different psychiatric disorders, including conduct disorder and attention deficit hyperactivity disorder (ADHD). Whether this increased risk

Tomasz Schneider; Nicholas Ilott; Giovana Brolese; Lisiane Bizarro; Philip J E Asherson; Ian P Stolerman

2011-01-01

249

A real-time regional adaptive exposure method for saving dose-area product in x-ray fluoroscopy  

SciTech Connect

Purpose: Reduction of radiation dose in x-ray imaging has been recognized as a high priority in the medical community. Here the authors show that a regional adaptive exposure method can reduce dose-area product (DAP) in x-ray fluoroscopy. The authors' method is particularly geared toward providing dose savings for the pediatric population. Methods: The scanning beam digital x-ray system uses a large-area x-ray source with 8000 focal spots in combination with a small photon-counting detector. An imaging frame is obtained by acquiring and reconstructing up to 8000 detector images, each viewing only a small portion of the patient. Regional adaptive exposure was implemented by varying the exposure of the detector images depending on the local opacity of the object. A family of phantoms ranging in size from infant to obese adult was imaged in anteroposterior view with and without adaptive exposure. The DAP delivered to each phantom was measured in each case, and noise performance was compared by generating noise arrays to represent regional noise in the images. These noise arrays were generated by dividing the image into regions of about 6 mm{sup 2}, calculating the relative noise in each region, and placing the relative noise value of each region in a one-dimensional array (noise array) sorted from highest to lowest. Dose-area product savings were calculated as the difference between the ratio of DAP with adaptive exposure to DAP without adaptive exposure. The authors modified this value by a correction factor that matches the noise arrays where relative noise is the highest to report a final dose-area product savings. Results: The average dose-area product saving across the phantom family was (42 {+-} 8)% with the highest dose-area product saving in the child-sized phantom (50%) and the lowest in the phantom mimicking an obese adult (23%). Conclusions: Phantom measurements indicate that a regional adaptive exposure method can produce large DAP savings without compromising the noise performance in the image regions with highest noise.

Burion, Steve; Funk, Tobias [Triple Ring Technologies, Inc., 39655 Eureka Drive, Newark, California 94560 (United States); Speidel, Michael A. [Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States)

2013-05-15

250

A real-time regional adaptive exposure method for saving dose-area product in x-ray fluoroscopy  

PubMed Central

Purpose: Reduction of radiation dose in x-ray imaging has been recognized as a high priority in the medical community. Here the authors show that a regional adaptive exposure method can reduce dose-area product (DAP) in x-ray fluoroscopy. The authors' method is particularly geared toward providing dose savings for the pediatric population. Methods: The scanning beam digital x-ray system uses a large-area x-ray source with 8000 focal spots in combination with a small photon-counting detector. An imaging frame is obtained by acquiring and reconstructing up to 8000 detector images, each viewing only a small portion of the patient. Regional adaptive exposure was implemented by varying the exposure of the detector images depending on the local opacity of the object. A family of phantoms ranging in size from infant to obese adult was imaged in anteroposterior view with and without adaptive exposure. The DAP delivered to each phantom was measured in each case, and noise performance was compared by generating noise arrays to represent regional noise in the images. These noise arrays were generated by dividing the image into regions of about 6 mm2, calculating the relative noise in each region, and placing the relative noise value of each region in a one-dimensional array (noise array) sorted from highest to lowest. Dose-area product savings were calculated as the difference between the ratio of DAP with adaptive exposure to DAP without adaptive exposure. The authors modified this value by a correction factor that matches the noise arrays where relative noise is the highest to report a final dose-area product savings. Results: The average dose-area product saving across the phantom family was (42 ± 8)% with the highest dose-area product saving in the child-sized phantom (50%) and the lowest in the phantom mimicking an obese adult (23%). Conclusions: Phantom measurements indicate that a regional adaptive exposure method can produce large DAP savings without compromising the noise performance in the image regions with highest noise.

Burion, Steve; Speidel, Michael A.; Funk, Tobias

2013-01-01

251

A CROSS-PROVINCE ANALYSIS OF URBAN AND RURAL INDOOR PM2.5 EXPOSURE IN CHINA USING TIME USE SURVEY  

NASA Astrophysics Data System (ADS)

In developing countries in Asia and other parts of the world, most energy sources used in the home are solid fuels such as coal and biomass (firewood, crop residue and animal dung). Particulate matter 2.5, consisting of particles with an aerodynamic diameter of 2.5 um or less, produced through combustion of these fuels inside the residence for cooking and heating has an adverse impact on people's health. We estimated PM2.5 exposure concentration in indoor microenvironment for each cohort of urban and rural area in ten provinces of China, using statistical data on time use survey and domestic energy consumption. The study found that, in each province, the exposure concentration in rural area was higher than in urban area, unemployed women between the ages of 60 and 64 had the highest estimate for exposure concentration at 3027 ?g/m3. The study also found that the exposure concentration for individual cohorts in each province was greatly affected by people's use of time indoors, fuel consumption such as coal or biomass and floor space.

Shimada, Yoko; Guo, Minna; Kurata, Gakuji; Matsuoka, Yuzuru

252

Post-antifungal effect and effects of sub-MIC concentrations on previously treated Candida spp.: influence of exposure time and concentration.  

PubMed

This study evaluates the influence of exposure time and concentration on the post-antifungal effect (PAFE) and the effect of sub-MIC concentrations (1/4 x MIC) on Candida albicans and C. glabrata in the PAFE stage (PAFSE). This stage was induced by pretreatment for 1.5, 3 or 12 h with 1 x, 4 x or 8 x MIC of 4 antifungal agents fundamental to modern candidiasis therapy. The length of the 2 effects studied was dependent on the concentration of the antifungal agent applied during pretreatment, as well as on the exposure time. An increase in the dose and/or longer pretreatment prolonged the duration of the PAFE and PAFSE in both species and with all the antifungal agents. Significant PAFEs were always observed for amphotericin B and 5-fluorocytosine (0.8-13 h and 0.6-10.8 h, respectively). These values were increased (by 2.3-8.7 h and 1.5-7.8 h, respectively) by posterior exposure to 1/4 x MIC of the respective antifungal agent. Neither ketoconazole nor fluconazole were able to induce significant PAFEs, even with exposures of up to 12 h duration and a dose of 8 x MIC. However, treatment with 1/4 x MIC of each of the 2 azoles led to significant PAFSEs in both yeast species, of up to 6.5 h duration with ketoconazole and 1.7 h with fluconazole, if the concentrations and/or exposure times were sufficiently high. PMID:12030393

García, M T; Llorente, M T; Mínguez, F; Prieto, J

2002-01-01

253

Nicotine exposure during adolescence leads to short- and long-term changes in spike timing-dependent plasticity in rat prefrontal cortex.  

PubMed

Adolescence is a critical period of brain development during which maturation of areas involved in cognitive functioning, such as the medial prefrontal cortex (mPFC), is still ongoing. Tobacco smoking during this age can compromise the normal course of prefrontal development and lead to cognitive impairments in later life. Recently, we reported that nicotine exposure during adolescence results in a short-term increase and lasting reduction in synaptic mGluR2 levels in the rat mPFC, causing attention deficits during adulthood. It is unknown how changed synaptic mGluR2 levels after adolescent nicotine exposure affect the ability of mPFC synapses to undergo long-term synaptic plasticity. Here, we addressed this question. To model nicotine exposure, adolescent (P34-P43) or adult (P60-P69) rats were treated with nicotine injections three times per day for 10 d. We found that, both during acute activation of nicotinic receptors in the adolescent mPFC as well as immediately following nicotine treatment during adolescence, long-term plasticity in response to timed presynaptic and postsynaptic activity (tLTP) was strongly reduced. In contrast, in the mPFC of adult rats 5 weeks after they received nicotine treatment during adolescence, but not during adulthood, tLTP was increased. Short- and long-term adaptation of mPFC synaptic plasticity after adolescent nicotine exposure could be explained by changed mGluR2 signaling. Blocking mGluR2s augmented tLTP, whereas activating mGluR2s reduced tLTP. Our findings suggest neuronal mechanisms by which exposure to nicotine during adolescence alters the rules for spike timing-dependent plasticity in prefrontal networks that may explain the observed deficits in cognitive performance in later life. PMID:22855798

Goriounova, Natalia A; Mansvelder, Huibert D

2012-08-01

254

Nicotine Exposure during Adolescence Leads to Short- and Long-Term Changes in Spike Timing-Dependent Plasticity in Rat Prefrontal Cortex  

PubMed Central

Adolescence is a critical period of brain development during which maturation of areas involved in cognitive functioning, such as the medial prefrontal cortex (mPFC), is still ongoing. Tobacco smoking during this age can compromise the normal course of prefrontal development and lead to cognitive impairments in later life. Recently, we reported that nicotine exposure during adolescence results in a short-term increase and lasting reduction in synaptic mGluR2 levels in the rat mPFC, causing attention deficits during adulthood. It is unknown how changed synaptic mGluR2 levels after adolescent nicotine exposure affect the ability of mPFC synapses to undergo long-term synaptic plasticity. Here, we addressed this question. To model nicotine exposure, adolescent (P34–P43) or adult (P60–P69) rats were treated with nicotine injections three times per day for 10 d. We found that, both during acute activation of nicotinic receptors in the adolescent mPFC as well as immediately following nicotine treatment during adolescence, long-term plasticity in response to timed presynaptic and postsynaptic activity (tLTP) was strongly reduced. In contrast, in the mPFC of adult rats 5 weeks after they received nicotine treatment during adolescence, but not during adulthood, tLTP was increased. Short-and long-term adaptation of mPFC synaptic plasticity after adolescent nicotine exposure could be explained by changed mGluR2 signaling. Blocking mGluR2s augmented tLTP, whereas activating mGluR2s reduced tLTP. Our findings suggest neuronal mechanisms by which exposure to nicotine during adolescence alters the rules for spike timing-dependent plasticity in prefrontal networks that may explain the observed deficits in cognitive performance in later life.

Goriounova, Natalia A.; Mansvelder, Huibert D.

2013-01-01

255

Exposure balancing and difference blurring to eliminate seam-lines in a real-time bird's eye view monitor  

Microsoft Academic Search

A Bird's Eye View Monitor usually shows visible seam-lines. Previous seam-line elimination methods limit the dynamic range of mosaicked image and require that the reference images are equal geometrically the regions that overlap. In this paper, we propose a camera model based alternative exposure compensation algorithm which controls brightness of reference images using calculated offset, and a seam-line difference blurring

2010-01-01

256

Time course of congener uptake and elimination in rats after short-term inhalation exposure to an airborne polychlorinated biphenyl (PCB) mixture.  

PubMed

Despite the continued presence of PCBs in indoor and ambient air, few studies have investigated the inhalation route of exposure. While dietary exposure has declined, inhalation of the semivolatile, lower-chlorinated PCBs has risen in importance. We measured the uptake, distribution, and time course of elimination of inhaled PCB congeners to characterize the pulmonary route after short-term exposure. Vapor-phase PCBs were generated from Aroclor 1242 to a nose-only exposure system and characterized for congener levels and profiles. Rats were exposed via inhalation acutely (2.4 mg/m3 for 2 h) or subacutely (8.2 mg/m3, 2 hx10 days), after which pulmonary immune responses and PCB tissue levels were measured. Animals acutely exposed were euthanized at 0, 1, 3, 6, and 12 h post exposure to assess the time course of PCB uptake and elimination. Following rapid absorption and distribution, PCBs accumulated in adipose tissue but decayed in other tissues with half-lives increasing in liver (5.6 h)

Hu, Xin; Adamcakova-Dodd, Andrea; Lehmler, Hans-Joachim; Hu, Dingfei; Kania-Korwel, Izabela; Hornbuckle, Keri C; Thorne, Peter S

2010-09-01

257

Impacts of ocean CO 2 disposal on marine life: II. Probabilistic plume exposure model used with a time?varying dose?response analysis  

Microsoft Academic Search

A method to evaluate aquatic mortality given a pollutant distribution is presented and applied to several sample low pH plumes representing various ocean CO2 disposal schemes. The method is an improvement over current analysis because it integrates the mortality due to time-varying exposure to low pH with the probabilistic experiences of passive organisms subject to turbulent lateral diffusion as they

Jennifer A. Caulfield; E. Eric Adams; David I. Auerbach; Howard J. Herzog

1997-01-01

258

New Automated Method for Determining Postantifungal Effect of Amphotericin B against Candida Species: Effects of Concentration, Exposure Time, and Area under the Curve  

PubMed Central

The postantifungal effect (PAFE) of amphotericin B was determined with a BacT/Alert automated system, which is based on the colorimetric detection of CO2. The levels of accuracy and precision of the automated method were high. Longer PAFEs were obtained for Candida albicans (P < 0.001), C. glabrata (P < 0.01), and C. krusei (P < 0.01) at increasing amphotericin B concentrations and exposure times.

Chryssanthou, Erja; Cars, Otto; Sjolin, Jan

2002-01-01

259

New automated method for determining postantifungal effect of amphotericin B against Candida species: effects of concentration, exposure time, and area under the curve.  

PubMed

The postantifungal effect (PAFE) of amphotericin B was determined with a BacT/Alert automated system, which is based on the colorimetric detection of CO(2). The levels of accuracy and precision of the automated method were high. Longer PAFEs were obtained for Candida albicans (P < 0.001), C. glabrata (P < 0.01), and C. krusei (P < 0.01) at increasing amphotericin B concentrations and exposure times. PMID:12435715

Chryssanthou, Erja; Cars, Otto; Sjölin, Jan

2002-12-01

260

Evaluation and validation of housekeeping genes in response to ionizing radiation and chemical exposure for normalizing RNA expression in real-time PCR  

Microsoft Academic Search

Gene expression changes are used with increasing frequency to assess the effects of exposure to environmental agents. Housekeeping (Hk) genes are essential in these analyses as internal controls for normalizing expression levels evaluated with Real-Time PCR (RT-PCR). Ideal Hk genes are constitutively expressed, do not respond to external stimuli and exhibit little or no sample-to-sample or run-to-run variation. Previous studies

Malathi Banda; Aryamani Bommineni; Robert A. Thomas; Leo S. Luckinbill; James D. Tucker

2008-01-01

261

A method for computing the damage level due to the exposure to an airborne chemical with a time-varying concentration.  

PubMed

The calculation of damage level due to the exposure to a toxic cloud is usually not included in most popular software, or it is included using techniques that do not take into account the variation in concentration over a period of time. In this work, a method is introduced for calculating the temporal evolution of the potential damage level and to obtain a more precise and descriptive estimation of this level. The proposed goal is: to estimate the maximum and minimum damage level experienced by a population due to the exposure to an airborne chemical with a time-varying concentration; to be able to assess the damage level experienced in a progressive way, as the exposure to the airborne chemical occurs. The method relies on transformations of time-concentration pairs on a continuum of damage level curves based on the available guideline levels, obtaining maximum and minimum approximations of the expected damage level for any exposure duration. Consequently, applying this method to transport model output data and demographic information, damage evolution in relation to time and space can be predicted, as well as its effect on the local population, which enables the determination of threat zones. The comparison between the proposed method and the current (Spanish and ALOHA) ones showed that the former can offer a more precise estimation and a more descriptive approach of the potential damage level. This method can be used by atmospheric dispersion models to compute damage level and graphically display the regions exposed to each guideline level on area maps. PMID:21395635

Acquesta, Alejandro D; Sánchez, Erica Yanina; Porta, Andres; Jacovkis, Pablo M

2011-09-01

262

The dissimilar time course of temporary threshold shifts and reduction of inhibition in the inferior colliculus following intense sound exposure.  

PubMed

Excessive noise exposure is known to produce an auditory threshold shift, which can be permanent or transient in nature. Recent studies showed that noise-induced temporary threshold shifts are associated with loss of synaptic connections to the inner hair cells and with cochlear nerve degeneration, which is reflected in a decreased amplitude of wave I of the auditory brainstem response (ABR). This suggests that, despite normal auditory thresholds, central auditory processing may be abnormal. We recorded changes in central auditory processing following a sound-induced temporary threshold shift. Anesthetized guinea pigs were exposed for 1 h to a pure tone of 11 kHz (124 dB sound pressure level). Hearing thresholds, amplitudes of ABR waves I and IV, and spontaneous and tone-evoked firing rates in the inferior colliculus (IC) were assessed immediately, one week, two weeks, and four weeks post exposure. Hearing thresholds were elevated immediately following overexposure, but recovered within one week. The amplitude of the ABR wave I was decreased in all sound-exposed animals for all test periods. In contrast, the ABR wave IV amplitude was only decreased immediately after overexposure and recovered within a week. The proportion of IC units that show inhibitory responses to pure tones decreased substantially up to two weeks after overexposure, especially when stimulated with high frequencies. The proportion of excitatory responses to low frequencies was increased. Spontaneous activity was unaffected by the overexposure. Despite rapid normalization of auditory thresholds, our results suggest an increased central gain following sound exposure and an abnormal balance between excitatory and inhibitory responses in the midbrain up to two weeks after overexposure. These findings may be associated with hyperacusis after a sound-induced temporary threshold shift. PMID:24650953

Heeringa, A N; van Dijk, P

2014-06-01

263

Comparison of physiological changes in carp, Cyprinus carpio, induced by several pollutants at sublethal concentrations. I. The dependency on exposure time  

SciTech Connect

Carp were exposed to 10 different pollutants at sublethal concentrations for 6, 24, or 72 hr. Blood, liver, and white muscle samples were taken after the exposure time together with samples of control handled fish. Serum concentrations of glucose, cortisol protein, and cholesterol were determined. Similarly, the liver and muscle glycogen contents were measured. The effects of the following pollutants were examined: aldrin (100 micrograms/liter), atrazine (100 micrograms/liter), DDT (50 micrograms/liter), dieldrin (20 micrograms/liter), endrin (2 micrograms/liter), hexachlorbenzene (100 micrograms/liter), lindane (100 micrograms/liter), methanol (1 ml/liter), 4-N-phenol (100 micrograms/liter), toluene (100 microliters/liter). The rises in serum glucose and cortisol were the most frequent changes occurring after exposure to the pollutants. A decline in plasma protein and cholesterol content was also often observed. Liver glycogen concentration increased first in most cases and was reduced after longer exposure. Muscle glycogen was affected differently, sometimes reduced by exposure to the pollutants. The experimental design allows for the gradual increase in toxicity of the pollutants used regarding the applied concentrations. Furthermore, the aim of the paper is to evaluate the tests for proof of toxicity of those chemicals. The determination of serum glucose and cortisol levels can be proposed as mostly useful. The clearest changes in all parameters were found after treatment with 100 micrograms/liter atrazine and 50 micrograms/liter DDT. When serum glucose and cortisol concentrations were quickly elevated, signs for exhaustion could be seen after 72 hr of exposure.

Gluth, G.; Hanke, W.

1985-04-01

264

A 1024×1 linear photodiode array sensor with fast readout speed flexible pixel-level integration time and high stability to UV light exposure  

NASA Astrophysics Data System (ADS)

In this paper, we demonstrate two types of new photodiode array (PDA) with fast readout speed and high stability to ultraviolet (UV) light exposure. One is a high full well capacity sensor specialized for absorption spectroscopy, the other one is a high sensitivity sensor for emission spectroscopy. By introducing multiple readout paths along the long side of the rectangle PD, both two PDAs have achieved more than 150 times faster readout speed compared with a general PDA structure with a single readout path along the short side of PD. By introducing a photodiode (PD) structure with a thin and steep dopant profile p+ layer formed on a flattened Si surface, a higher stability of the light sensitivity to UV light exposure was confirmed compared with a general PD structure for conventional PDAs.

Akutsu, Takahiro; Kawada, Shun; Koda, Yasumasa; Nakazawa, Taiki; Kuroda, Rihito; Sugawa, Shigetoshi

2014-03-01

265

A new perspective on human health risk assessment: development of a time dependent methodology and the effect of varying exposure durations.  

PubMed

We present a new Time Dependent Risk Assessment (TDRA) that stochastically considers how joint uncertainty and inter-individual variability (JUV) associated with human health risk change as a function of time. In contrast to traditional, time independent assessments of risk, this new formulation relays information on when the risk occurs, how long the duration of risk is, and how risk changes with time. Because the true exposure duration (ED) is often uncertain in a risk assessment, we also investigate how varying the magnitude of fixed size durations (ranging between 5 and 70 years) of this parameter affects the distribution of risk in both the time independent and dependent methodologies. To illustrate this new formulation and to investigate these mechanisms for sensitivity, an example of arsenic contaminated groundwater is used in conjunction with two scenarios of different environmental concentration signals resulting from rate dependencies in geochemical reactions. Cancer risk is computed and compared using environmental concentration ensembles modeled with sorption as 1) a linear equilibrium assumption (LEA) and 2) first order kinetics (Kin). Results show that the information attained in the new time dependent methodology reveals how the uncertainty in other time-dependent processes in the risk assessment may influence the uncertainty in risk. We also show that individual susceptibility also affects how risk changes in time, information that would otherwise be lost in the traditional, time independent methodology. These results are especially pertinent for forecasting risk in time, and for risk managers who are assessing the uncertainty of risk. PMID:22684123

Siirila, Erica R; Maxwell, Reed M

2012-08-01

266

Time- and state-dependent effects of methanethiosulfonate ethylammonium (MTSEA) exposure differ between heart and skeletal muscle voltage-gated Na(+) channels.  

PubMed

The substituted-cysteine scanning method (SCAM) is used to study conformational changes in proteins. Experiments using SCAM involve site-directed mutagenesis to replace native amino acids with cysteine and subsequent exposure to a methanethiosulfonate (MTS) reagent such as methanethiosulfonate ethylammonium (MTSEA). These reagents react with substituted-cysteines and can provide functional information about relative positions of amino acids within a protein. In the human heart voltage-gated Na(+) channel hNav1.5 there is a native cysteine at position C373 that reacts rapidly with MTS reagents resulting in a large reduction in whole-cell Na(+) current (I(Na)). Therefore, in order to use SCAM in studies in this isoform, this native cysteine is mutated to a non-reactive residue, e.g., tyrosine. This mutant, hNav1.5-C373Y, is resistant to the MTS-mediated decrease in I(Na). Here we show that this resistance is time- and state-dependent. With relatively short exposure times to MTSEA (<4min), there is little effect on I(Na). However, with longer exposures (4-8min), there is a large decrease in I(Na), but this effect is only found when hNav1.5-C373Y is inactivated (fast or slow) - MTSEA has little effect in the closed state. Additionally, this long-term, state-dependent effect is not seen in human skeletal muscle Na(+) channel isoform hNav1.4, which has a native tyrosine at the homologous site C407. We conclude that differences in molecular determinants of inactivation between hNav1.4 and hNav1.5 underlie the difference in response to MTSEA exposure. PMID:22155680

O'Reilly, John P; Shockett, Penny E

2012-03-01

267

Time- and state-dependent effects of methanethiosulfonate ethylammonium (MTSEA) exposure differ between heart and skeletal muscle voltage-gated Na+ channels  

PubMed Central

The substituted-cysteine scanning method (SCAM) is used to study conformational changes in proteins. Experiments using SCAM involve site-directed mutagenesis to replace native amino acids with cysteine and subsequent exposure to a methanethiosulfonate (MTS) reagent such as methanethiosulfonate ethylammonium (MTSEA). These reagents react with substituted-cysteines and can provide functional information about relative positions of amino acids within a protein. In the human heart voltage-gated Na+ channel hNav1.5 there is a native cysteine at position C373 that reacts rapidly with MTS reagents resulting in a large reduction in whole-cell Na+ current (INa). Therefore, in order to use SCAM in studies in this isoform, this native cysteine is mutated to a non-reactive residue, e.g., tyrosine. This mutant, hNav1.5-C373Y, is resistant to the MTS-mediated decrease in INa. Here we show that this resistance is time- and state-dependent. With relatively short exposure times to MTSEA (<4 min), there is little effect on INa. However, with longer exposures (4–8 min), there is a large decrease in INa, but this effect is only found when hNav1.5-C373Y is inactivated (fast or slow) — MTSEA has little effect in the closed state. Additionally, this long-term, state-dependent effect is not seen in human skeletal muscle Na+ channel isoform hNav1.4, which has a native tyrosine at the homologous site C407. We conclude that differences in molecular determinants of inactivation between hNav1.4 and hNav1.5 underlie the difference in response to MTSEA exposure.

O'Reilly, John P.; Shockett, Penny E.

2012-01-01

268

Are variance components of exposure heterogeneous between time periods and factories in the European carbon black industry?  

PubMed

Occupational exposure to chemical agents can vary enormously within- and between-workers, even when carrying out the same jobs. When repeated measurements are available, the variance components can be estimated using random- or mixed-effects models. Pooling the variance components across the fixed effects, in mixed-effects models, reduces the complexity of the models; especially, when there are a large number of fixed effects. The analyses presented in this paper tested the assumptions of homogeneity in the variance components between factories and surveys for inhalable dust exposure in the European carbon black manufacturing industry. In total, 5296 measurements from 1771 workers were available collected during two surveys carried out between 1991 and 1995. Workers were grouped into eight job categories, and for each of these separate mixed-effects models were developed, including factory, survey and in some cases the interaction term as the fixed effects. The likelihood ratio test was used to test the assumptions of homogeneity of the variance components. Statistically significant heterogeneity of the variance components was observed for two of the eight job categories, 'Fitter/Welder' and 'Warehouseman'. The heterogeneity was due mainly to differences in variance between the factories. When estimating the probability of overexposure for all the factories combined, there was little difference between the models with and without heterogeneous variance components for 'Fitters/Welders'. For the 'Warehousemen' the probability of overexposure in the last survey changed marginally from 4% in the pooled model to 6% in the heterogeneous model. Larger differences between the models were observed when estimating the probability of overexposure for individual factories, which was due to over- or under-estimation of the variance components in the pooled models. In conclusion, for most job categories pooling of the variance components appears to be justified in this database. In addition, no large differences were found when determining the industry-wide probability of 'overexposure' when comparing the pooled with the heterogeneous models. However, when evaluating the factory-specific probability of 'overexposure' or when using the models to provide exposure estimates for epidemiological studies heterogeneity in the variance components should be investigated. PMID:16126761

Van Tongeren, Martie; Burstyn, Igor; Kromhout, Hans; Gardiner, Kerry

2006-01-01

269

Transplacental Carcinogenesis with Dibenzo[def,p]chrysene (DBC): Timing of Maternal Exposures Determines Target Tissue Response in Offspring  

PubMed Central

Dibenzo[def,p]chrysene (DBC) is a transplacental carcinogen in mice (15 mg/kg; gestation day (GD) 17). To mimic residual exposure throughout pregnancy, dams received 4 smaller doses of DBC (3.75 mg/kg) on GD 5, 9, 13 and 17. This regimen alleviated the previously established carcinogenic responses in the thymus, lung, and liver. However, there was a marked increase in ovarian tumors (females) and hyperplastic testes (males). [14C]-DBC (GD 17) dosing revealed transplacental distribution to fetal tissues at 10-fold lower concentrations than in paired maternal tissue and residual [14C] 3 weeks post dose. This study highlights the importance of developmental stage in susceptibility to environmental carcinogens.

Shorey, Lyndsey; Castro, David J.; Baird, William; Siddens, Beth; Lohr, Christiane; Matzke, Melissa; Waters, Katrina M.; Corley, Richard A.; Williams, David E.

2011-01-01

270

On the distribution of multicomponent mixtures over generalized exposure time in subsurface flow and reactive transport: Theory and formulations for residence-time-dependent sorption/desorption with memory  

NASA Astrophysics Data System (ADS)

Mass conservation in the extended coordinates of space, time, and one or more exposure-time dimensions is used as a basis for the development of equations that govern the evolution of residence-time distributions of material undergoing convective-dispersive reactive transport to particular phases or states involved in the mass transfer reactions. The validity of using a continuous motion in the new exposure-time coordinate for tracking material residence-time distributions is placed in the context of the no-recrossing rule of transition state theory and arises from the representation of the reaction as a series of Bernoulli trials. A set of constitutive laws are given for describing some of the different ways in which material residence times and thus memory may be accounted. The model approach is illustrated through generalization of the conventional two-site reactive transport model to include memory of phase association. The resulting forms of the two-site model with memory are expressed and examined in light of the no-recrossing assumption.

Ginn, Timothy R.

2000-10-01

271

Vitrification of in vitro mature alpaca oocyte: effect of ethylene glycol concentration and time of exposure in the equilibration and vitrification solutions.  

PubMed

The effect of different ethylene glycol concentrations, times of exposure and vitrification procedure on viability, cleavage and blastocyst rate of in vitro matured alpaca oocytes chemically activated after vitrification was analyzed. In Experiment 1, oocytes were incubated for 12-15 min with different concentrations of ethylene glycol (EG) in the equilibration solution (ES) followed by chemical activation and in vitro cultured for 8 days to determine oocyte viability, cleavage and blastocyst rates. In Experiment 2, oocytes were incubated in the equilibration solution containing 4% of EG for 12-15 min and then randomly assigned to vitrification solutions containing 25, 35 or 45% of EG for 30s, vitrified and stored at -196°C. In Experiment 3, oocytes were incubated in the equilibration solution containing 4% of EG for 12-15 min and then randomly assigned to the vitrification solution containing 35% of EG for 15, 30 or 45s, vitrified and stored at -196°C. For Experiments 2 and 3, non-vitrified and vitrified oocytes were activated and cultured in vitro. In Experiment 1, oocyte viability was lowest at concentrations of 6 or 8%, intermediate at 2 or 4% and highest at 0% of EG. Oocyte viability and cleavage rate were affected by EG concentration, time of exposure in the vitrification solution or vitrification procedure in Experiment 2 and 3. Alpaca oocytes were viable after vitrification, given that oocyte viability, cleavage and blastocyst rate were affected by the vitrification procedure, EG concentration and time of exposure in the equilibration and vitrification solutions. PMID:24231049

Ruiz, J; Landeo, L; Mendoza, J; Artica, M; Correa, J E; Silva, M; Miragaya, M; Ratto, M H

2013-12-01

272

Time Courses of Changes in Phospho- and Total- MAP Kinases in the Cochlea after Intense Noise Exposure  

PubMed Central

Mitogen-activated protein kinases (MAP kinases) are intracellular signaling kinases activated by phosphorylation in response to a variety of extracellular stimuli. Mammalian MAP kinase pathways are composed of three major pathways: MEK1 (mitogen-activated protein kinase kinase 1)/ERK 1/2 (extracellular signal-regulated kinases 1/2)/p90 RSK (p90 ribosomal S6 kinase), JNK (c-Jun amino (N)-terminal kinase)/c-Jun, and p38 MAPK pathways. These pathways coordinately mediate physiological processes such as cell survival, protein synthesis, cell proliferation, growth, migration, and apoptosis. The involvement of MAP kinase in noise-induced hearing loss (NIHL) has been implicated in the cochlea; however, it is unknown how expression levels of MAP kinase change after the onset of NIHL and whether they are regulated by transient phosphorylation or protein synthesis. CBA/J mice were exposed to 120-dB octave band noise for 2 h. Auditory brainstem response confirmed a component of temporary threshold shift within 0–24 h and significant permanent threshold shift at 14 days after noise exposure. Levels and localizations of phospho- and total- MEK1/ERK1/2/p90 RSK, JNK/c-Jun, and p38 MAPK were comprehensively analyzed by the Bio-Plex® Suspension Array System and immunohistochemistry at 0, 3, 6, 12, 24 and 48 h after noise exposure. The phospho-MEK1/ERK1/2/p90 RSK signaling pathway was activated in the spiral ligament and the sensory and supporting cells of the organ of Corti, with peaks at 3–6 h and independently of regulations of total-MEK1/ERK1/2/p90 RSK. The expression of phospho-JNK and p38 MAPK showed late upregulation in spiral neurons at 48 h, in addition to early upregulations with peaks at 3 h after noise trauma. Phospho-p38 MAPK activation was dependent on upregulation of total-p38 MAPK. At present, comprehensive data on MAP kinase expression provide significant insight into understanding the molecular mechanism of NIHL, and for developing therapeutic models for acute sensorineural hearing loss.

Maeda, Yukihide; Fukushima, Kunihiro; Omichi, Ryotaro; Kariya, Shin; Nishizaki, Kazunori

2013-01-01

273

Time courses of changes in phospho- and total- MAP kinases in the cochlea after intense noise exposure.  

PubMed

Mitogen-activated protein kinases (MAP kinases) are intracellular signaling kinases activated by phosphorylation in response to a variety of extracellular stimuli. Mammalian MAP kinase pathways are composed of three major pathways: MEK1 (mitogen-activated protein kinase kinase 1)/ERK 1/2 (extracellular signal-regulated kinases 1/2)/p90 RSK (p90 ribosomal S6 kinase), JNK (c-Jun amino (N)-terminal kinase)/c-Jun, and p38 MAPK pathways. These pathways coordinately mediate physiological processes such as cell survival, protein synthesis, cell proliferation, growth, migration, and apoptosis. The involvement of MAP kinase in noise-induced hearing loss (NIHL) has been implicated in the cochlea; however, it is unknown how expression levels of MAP kinase change after the onset of NIHL and whether they are regulated by transient phosphorylation or protein synthesis. CBA/J mice were exposed to 120-dB octave band noise for 2 h. Auditory brainstem response confirmed a component of temporary threshold shift within 0-24 h and significant permanent threshold shift at 14 days after noise exposure. Levels and localizations of phospho- and total- MEK1/ERK1/2/p90 RSK, JNK/c-Jun, and p38 MAPK were comprehensively analyzed by the Bio-Plex® Suspension Array System and immunohistochemistry at 0, 3, 6, 12, 24 and 48 h after noise exposure. The phospho-MEK1/ERK1/2/p90 RSK signaling pathway was activated in the spiral ligament and the sensory and supporting cells of the organ of Corti, with peaks at 3-6 h and independently of regulations of total-MEK1/ERK1/2/p90 RSK. The expression of phospho-JNK and p38 MAPK showed late upregulation in spiral neurons at 48 h, in addition to early upregulations with peaks at 3 h after noise trauma. Phospho-p38 MAPK activation was dependent on upregulation of total-p38 MAPK. At present, comprehensive data on MAP kinase expression provide significant insight into understanding the molecular mechanism of NIHL, and for developing therapeutic models for acute sensorineural hearing loss. PMID:23484051

Maeda, Yukihide; Fukushima, Kunihiro; Omichi, Ryotaro; Kariya, Shin; Nishizaki, Kazunori

2013-01-01

274

Study on hydrofluoric acid-based clad etching and chemical sensing characteristics of fiber Bragg gratings of different reflectivity fabricated under different UV exposure times  

NASA Astrophysics Data System (ADS)

An experimental study on hydrofluoric acid (HF)-based clad etching and chemical sensing characteristics of fiber Bragg gratings (FBG) of different reflectivity fabricated under different UV (255 nm) exposure times is presented. Two FBGs of reflectivity 11% and 93% were inscribed by phase mask-based exposition of the photosensitive fibers by a 5.5 kHz repetition rate of 255 nm UV pulses for 15 s and 10 min, respectively. These two FBGs, employed in an HF-based clad etching experiment, revealed a much higher etching rate of 2.03 ?m/min for the grating of reflectivity 11% as compared to 1.69 ?m/min for the grating of reflectivity 93%. The performance of these etched FBGs were also studied for refractive index sensing of the chemicals ethanol and ethylene glycol under different fiber etching times, hence of different residual cladding diameter. It was observed that the same refractive index sensitivity for both the chemicals could be achieved under smaller etching time, i.e., larger residual cladding diameter, for the FBG with lower reflectivity. This differentiating behavior of FBGs under etching and sensing may be linked to the different degree of densification in fused silica fiber cladding under different UV fluence exposures.

Kumar, Jitendra; Mahakud, Ramakant; Prakash, Om; Dixit, Sudhir Kumar

2013-05-01

275

Volatile compounds and phenolic composition of virgin olive oil: optimization of temperature and time of exposure of olive pastes to air contact during the mechanical extraction process.  

PubMed

The operative conditions of malaxation such as temperature and time of exposure of olive pastes to air contact (TEOPAC) affect volatile and phenolic composition of virgin olive oil (VOO) and, as a consequence, its sensory and healthy qualities. In this paper, optimal temperature and TEOPAC during malaxation were studied, in lab scale, in two Italian cultivars using phenolic compounds, volatile composition, and sensory analysis of VOO as markers. The optimal temperature and TEOPAC, selected by response surface modeling,were cultivar-dependent being 30 min of TEOPAC at the lowest temperature investigated (22 degrees C) and 0 min of TEOPAC at 26 degrees C for Frantoio and Moraiolo cultivars, respectively. PMID:14690383

Servili, Maurizio; Selvaggini, Roberto; Taticchi, Agnese; Esposto, Sonia; Montedoro, GianFrancesco

2003-12-31

276

Adaptation of Natural Microbial Communities to Degradation of Xenobiotic Compounds: Effects of Concentration, Exposure Time, Inoculum, and Chemical Structure †  

PubMed Central

Adaptation of microbial communities to faster degradation of xenobiotic compounds after exposure to the compound was studied in ecocores. Radiolabeled test compounds were added to cores that contained natural water and sediment. Adaptation was detected by comparing mineralization rates or disappearance of a parent compound in preexposed and unexposed cores. Microbial communities in preexposed cores from a number of freshwater sampling sites adapted to degrade p-nitrophenol faster; communities from estuarine or marine sites did not show any increase in rates of degradation as a result of preexposure. Adaptation was maximal after 2 weeks and was not detectable after 6 weeks. A threshold concentration of 10 ppb (10 ng/ml) was observed; below this concentration no adaptation was detected. With concentrations of 20 to 100 ppb (20 to 100 ng/ml), the biodegradation rates in preexposed cores were much higher than the rates in control cores and were proportional to the concentration of the test compound. In addition, trifluralin, 2,4-dichlorophenoxyacetic acid, and p-cresol were tested to determine whether preexposure affected subsequent biodegradation. Microbial communities did not adapt to trifluralin. Adaptation to 2,4-dichlorophenoxyacetic acid was similar to adaptation to nitrophenol. p-Cresol was mineralized rapidly in both preexposed and unexposed communities.

Spain, Jim C.; Van Veld, P. A.

1983-01-01

277

Adaptation of natural microbial communities to degradation of xenobiotic compounds: effects of concentration, exposure time, inoculum, and chemical structure  

SciTech Connect

Adaptation of microbial communities to faster degradation of xenobiotic compounds after exposure to the compound was studied in ecocores. Radiolabeled test compounds were added to cores that contained natural water and sediment. Adaptation was detected by comparing mineralization rates or disappearance of a parent compound in preexposed and unexposed cores. Microbial communities in preexposed cores from a number of freshwater sampling sites adapted to degrade p-nitrophenol faster; communities from estuarine or marine sites did not show any increase in rates of degradation as a result of preexposure. Adaptation was maximal after 2 weeks and was not detectable after 6 weeks. A threshold concentration of 10 ppb (10 ng/ml) was observed; below this concentration no adaptation was detected. With concentrations of 20 to 100 ppb (20 to 100 ng/ml), the biodegradation rates in preexposed cores were much higher than the rates in control cores and were proportional to the concentration of the test compound. In addition, trifluralin, 2,4-dichlorophenoxyacetic acid, and p-cresol were tested to determine whether preexposure affected subsequent biodegradation. Microbial communities did not adapt to trifluralin. Adaptation to 2,4-dichlorophenoxyacetic acid was similar to adaptation to nitrophenol. p-Cresol was mineralized rapidly in both preexposed and unexposed communities.

Spain, U.C. (U.S. Environmental Protection Agency, Gulf Breeze, FL); Van Veld, P.A.

1983-02-01

278

Time- and tissue-dependent polychlorinated biphenyl residues in hairless mice after exposure to polychlorinated biphenyl-contaminated soil.  

PubMed

Four groups of 16 age-matched female Crl:SKH1-hrBR hairless mice were exposed to either control soil or polychlorinated biphenyl (PCB)-contaminated soil (retrieved from an electrical waste landfill in Southern Illinois) for 11 weeks. The mice were exposed in a study to determine interactions between environmental PCBs and ultraviolet radiation (UVR), but the UVR group did not differ and provided a replicate for the residue study. Ear biopsies were performed immediately after the termination of soil exposure. The mice were maintained in regular bedding for 37 weeks thereafter. The ear-skin, trunk-skin, fat-pad, and liver samples were collected and weighed at the end of the study (week 48) and analyzed for PCB residues. A total of 141 PCB congeners were target analytes. There were significant differences in body weights and food consumption from week 2 to 28. The liver weights of mice treated with PCB only were significantly greater than those of UVR-treated mice. The fat-pad weight did not differ among treated groups. PCB residues in the ear biopsies specimens of mice exposed to contaminated soil were 342.3 and 317.2 ppm in the PCB- and PCB + UVR-treated groups, respectively, and contained both persistent and episodic congeners. After 37 weeks of isolation from soil, the ear PCB residues decreased to 21.5 ppm (PCB group) and 14.5 ppm (PCB + UVR group), and only persistent congeners contributed to the total PCB residues. The accumulation of PCB residues was highest in the fat pad (fat pad > ear skin > trunk skin > liver) in both PCB +/- UVR groups at the end of the study. However, the percentage of individual congeners contributing to total PCBs in these different tissues did not differ. PMID:15981037

Imsilp, K; Wiedenmann, L; Bordson, G O; Morrow, C K; Cope, R; Hansen, L G

2005-07-01

279

Timing and extent of Quaternary glaciations in the Tianger Range, eastern Tian Shan, China, investigated using 10Be surface exposure dating  

NASA Astrophysics Data System (ADS)

Reconstructing glacial chronologies with consistent methods is critical for efforts to examine the timing and pattern of past climate change. Cosmogenic 10Be surface exposure dating has been widely used to constrain the timing of glacial events on the Tibetan Plateau and in Central Asia. However, few such studies have been conducted in the Chinese Tian Shan and available 10Be ages from this region have only provided evidence for glacial events during the global Last Glacial Maximum (gLGM) and Lateglacial. Here, we present 45 10Be surface exposure ages from glacial landforms in the Ala and Daxi valleys, two formerly glaciated valleys draining the Tianger Range, eastern Tian Shan. Combined with previously published 10Be surface exposure ages from the Daxi Valley in the source area of the Urumqi River, the new ages record five major glacial events during Marine Oxygen Isotope Stages (MIS) 6 or older, 4, 3, 2, and 1 (during the Little Ice Age, LIA). Landforms from glacial events since MIS 2 are found on the northern slope of the Tianger Range (Daxi Valley), whereas evidence for the older glacial events is only preserved on its southern slope (Ala Valley). This disparity may be caused by different preservation- and micro-climatic conditions on the northern and southern slopes of this mountain range, due to differences in gradient and aspect. The LIA glacial advances are apparently the only Holocene glacial event recorded in this area. Earlier Holocene glacial events were probably so restricted in extent that they were destroyed by subsequent LIA advances.

Li, Yingkui; Liu, Gengnian; Chen, Yixin; Li, Yanan; Harbor, Jon; Stroeven, Arjen P.; Caffee, Marc; Zhang, Mei; Li, Chuanchuan; Cui, Zhijiu

2014-08-01

280

Time-dependent alterations in growth, photosynthetic pigments and enzymatic defense systems of submerged Ceratophyllum demersum during exposure to the cyanobacterial neurotoxin anatoxin-a.  

PubMed

Recently, aquatic macrophytes have been considered as promising tools for eco-friendly water management with a low running cost. However, only little information is available thus far regarding the metabolic capacity of macrophytes for coping with cyanobacterial toxins (cyanotoxins) in the aquatic environment. Cyanotoxins have become emerging contaminants of great concern due to the high proliferation of cyanobacteria (cyanobacterial bloom) accelerated by eutrophication and climate change. Anatoxin-a, one of the common and major cyanotoxins, is suggested as a high priority water pollutant for regulatory consideration owing to its notoriously rapid mode of action as a neurotoxin. In this study, the time-course metabolic regulation of the submerged macrophyte Ceratophyllum demersum (C. demersum) was investigated during exposure to anatoxin-a at an environmentally relevant concentration (15 ?g/L). Biotransformation and antioxidative systems in C. demersum responded positively to anatoxin-a through the promoted synthesis of most of the involved enzymes within 8h. Maximum enzyme activities were exhibited after 24 or 48 h of exposure to anatoxin-a. However, an apparent decline in enzyme activities was also observed at longer exposure duration (168 and 336 h) in company with high steady-state levels of cell internal H?O?, which showed its highest level after 48 h. Meanwhile, irreversible inhibitory influence on chlorophyll content (vitality) was noticed, whereas the ratio of carotenoids to total chlorophyll was increased with the increase in exposure duration. Consequently, the reduction in growth (biomass) of C. demersum was observed in sub-chronic exposure to anatoxin-a (8 weeks). Overall results clearly indicate, on the one hand, that anatoxin-a causes negative allelopathic effects on the macrophyte by inducing oxidative stress. On the other hand, the macrophyte might have interactions with anatoxin-a, based on the prompt reaction of its enzymatic defense systems to the toxin. The result obtained from the present study could contribute to the improvement of basic knowledge about the ecological impact of anatoxin-a and the environmental fate of the toxin in the aquatic environment. PMID:23685387

Ha, Mi-Hee; Pflugmacher, Stephan

2013-08-15

281

Diverging Experiences during Out-of-School Time: The Race Gap in Exposure to After-School Programs  

ERIC Educational Resources Information Center

There is considerable interest in identifying ways to close the Black-White achievement gap. This study examines race differences in children's participation in after-school programs, an out-of-school time experience that may influence children's achievement. Using nationally representative data spanning 1995-2005, the authors find that African…

Hynes, Kathryn; Sanders, Felicia

2011-01-01

282

Modeling and Simulation of the Time Course of Asenapine Exposure Response and Dropout Patterns in Acute Schizophrenia  

Microsoft Academic Search

Modeling and simulation were utilized to characterize the efficacy dose response of sublingual asenapine in patients with schizophrenia and to understand the outcomes of six placebo-controlled trials in which placebo responses and dropout rates varied. The time course of total Positive and Negative Syndrome Scale (PANSS) scores was characterized for placebo and asenapine treatments in a pharmacokinetic–pharmacodynamic model in which

LE Friberg; R de Greef; T Kerbusch; MO Karlsson

2009-01-01

283

Individual-level PM2.5 exposure and the time course of impaired heart rate variability: the APACR Study  

Microsoft Academic Search

In 106 community-dwelling middle-aged non-smokers we examined the time-course and the acute effects of fine particles (PM2.5) on heart rate variability (HRV), which measures cardiac autonomic modulation (CAM). Twenty-four hours beat-to-beat ECG data were visually examined. Artifacts and arrhythmic beats were removed. Normal beat-to-beat RR data were used to calculate HRV indices. Personal PM2.5 nephelometry was used to estimate 24-h

Fan He; Michele L Shaffer; Xian Li; Sol Rodriguez-Colon; Deborah L Wolbrette; Ronald Williams; Wayne E Cascio; Duanping Liao

2011-01-01

284

Time  

ERIC Educational Resources Information Center

When a teacher gives their time to a student, it is more significant to that student than anything else one could do for him or her. Music teachers deal with time all the time. Someone once said that "time is like money: we never have enough." This may seem true; however, time is not like money. One can make more money, but one cannot "make time."…

Circle, David

2005-01-01

285

Influence of exposure time to saliva and antioxidant treatment on bond strength to enamel after tooth bleaching: an in situ study  

PubMed Central

Objectives This study evaluated the influence of different exposure times to saliva in situ in comparison with an antioxidant treatment on composite resin bond strength to human enamel restored after tooth bleaching. Material and Methods Forty human teeth specimens measuring 5x5 mm were prepared and randomly allocated into 5 groups with 8 specimens each: Gct (control group, restored on unbleached enamel); Gbl (restored immediately after bleaching); Gsa (bleached, treated with 10% sodium ascorbate gel for 60 min and restored); G7d (bleached, exposed to saliva in situ for 7 days and restored); and G14d (bleached, exposed to saliva in situ for 14 days and restored). Restored samples were cut into 0.8 mm2 sticks that were tested in microtensile. Specimens were microscopically analyzed and failure modes were classified as adhesive, cohesive, or mixed. Pretest and cohesive failures were not considered in the statistical analysis, which was performed with one-way ANOVA and Tukey's post-hoc test (?=0.05), with the dental specimen considered as the experimental unit. Results Mean bond strength results found for Gbl in comparison with Gct indicated that bleaching significantly reduced enamel adhesiveness (P<0.01). However, no statistically significant differences were found between Gct, Gsa and G7d (P>0.05). Bond strength found for G14d was significantly higher than for Gsa (P<0.01). Fractures modes were predominantly of a mixed type. Conclusions Bonding strength to bleached enamel was immediately restored with the application of sodium ascorbate and exposure to human saliva in situ for at least 7 days. Best results were obtained with exposure to human saliva in situ for 14 days. Treatment with sodium ascorbate gel for 60 min may be recommended in cases patients cannot wait for at least 7 days for adhesive techniques to be performed.

MIRANDA, Thais Aglaet Matos; MOURA, Sandra Kiss; AMORIM, Vitor Hugo de Oliveira; TERADA, Raquel Sano Suga; PASCOTTO, Renata Correa

2013-01-01

286

Observations on dietary aluminum level, time duration exposure to dietary aluminum, and the influence of specific dietary blocking agents on tissue aluminum accumulation in the rat  

SciTech Connect

Two experiments were conducted to observe the association of dietary aluminum (Al) with tissue Al accumulation. Other objectives included: to determine if alginic acid (AA) and pectin (P) in the diet could inhibit Al accumulation in tissues, and to relate time of exposure of dietary Al to Al tissue accumulation. The first experiment was conducted with a test diet feeding period of 35 days in a factorial arrangement of treatments with 24 rats, six rats per treatment. The dietary treatments were: groups 0 and 1, no added dietary Al (Al < 20 ppm) with or without 5% AA; groups 2 and 3, 400 ppm additional dietary Al with or without 5% AA. Kidney tissue analyzed by neutron activation showed no significant Al accumulation, or influence of the blocking agent. The second experiment was conducted over two time intervals (phase I with 24 rats for 28 days, and phase II with 26 rats for 56 days) and was done with 7 different diets. The diets included a control (basal with no added Al or blocking agent), the basal with 425 or 640 ppm Al added, with 5% AA or 5% P added to each Al test level. The Al source for both experiments was aluminum dibasic acetate. Tissues collected and pooled for analyses by inductively coupled plasma atomic emission spectroscopy included bone, brain, and kidney. The addition of 425 ppm Al to the diets stimulated body weight gain by about 10% relative to the controls. The blocking agents suppressed Al-induced weight gain, although AA stimulated feed intake (P < 0.05). Trends in Al accumulation appeared to occur in bone and brain tissues associated with dietary Al; but independent of blocking agents and independent of time exposure to the dietary Al.

Kettleson, K.C.A.

1986-01-01

287

Heavy equipment maintenance exposure assessment: using a time-activity model to estimate surrogate values for replacement of missing data.  

PubMed

This study on four pieces of heavy construction equipment was conducted to determine the concentration of airborne asbestos fibers during in-frame maintenance and repair activities, which included aggressive techniques that resulted in visible dust from work involving friction products and gaskets. Despite execution of a carefully planned sampling strategy, approximately 10% (47) of the samples collected could not be analyzed due to overloading or filter damage. To include the overloaded samples in the data analysis, surrogate values were estimated following a time-activity model. Twelve long-term personal samples, 2 short-term, 30-min personal samples, and 31 long-term area samples were modeled. Personal and area time-weighted average (TWA) data were analyzed both with and without the estimated surrogate values and compared. A total of 444 samples were collected over 9 days. Four experienced heavy equipment mechanics removed and replaced friction products and gaskets. Samples were analyzed using NIOSH Method 7400 Phase Contrast Microscopy followed by NIOSH Method 7402 Transmission Electron Microscopy. Sample data information including the surrogate values for the full-shift, TWA personal sample results ranged from 0.002 to 0.064 asbestos f/cc. Personal, short-term, 30-min sample results, including the two surrogate values, ranged from 0.038 to 0.561 asbestos f/cc. Full-shift TWA area samples, including the 31 surrogate values, ranged from 0.005 to 0.039 asbestos f/cc. Area air sample results at the end of the project were similar to levels measured before the start of the project. No fiber concentration buildup within the work area was indicated over the 9-day study. All full-shift personal and area TWA sample results were below 0.1 f/cc, and short-term 30-min personal samples were below 1.0 f/cc. Statistical results of the sample data with and without the surrogate values were consistent. Use of the time-activity model reduced the uncertainty associated with this data analysis and provided a consistent logical process for estimating surrogate values to replace missing data. PMID:17503297

Boelter, Fred W; Spencer, John W; Simmons, Catherine E

2007-07-01

288

Identification of genes differentially expressed in clams Ruditapes philippinarum in response to endosulfan after different exposure time.  

PubMed

This study reports molecular biomarkers potentially associated with resistance or sensitivity to the impact of endosulfan in clams, Ruditapes philippinarum. Genomic analysis was made applying suppression subtractive hybridization (SSH) to identify genes up- and down-regulated in calms exposed to 0.5 ?g/L endosulfan for 1d and 10d. Results obtained from the SSH library revealed 360 different sequences regulated by endosulfan, which correspond to nine major physiological functions. To validate the expression profiles from SSH, 13 genes regulated by endosulfan were measured by quantitative real-time PCR. This study provides information for the characterization of potential molecular biomarker that may be used in future environmental monitoring and to investigate the mechanisms of stress to endosulfan in clams/marine invertebrates. PMID:23290617

Tao, Yanxia; Pan, Luqing; Zhang, Hui; Liu, Na

2013-03-01

289

Visualisation and identification of peak exposure events in aluminium smelter pot rooms using hydrogen fluoride and aerosol real-time portable spectrometers.  

PubMed

A recently developed novel portable real-time hydrogen fluoride spectrometer was used with an aerosol PM10 spectrometer under a PIMEX telemetric measurement strategy to visualize and identify simultaneous occupational air peak exposure events to hydrogen fluoride and PM10 aerosol sub-fractions in aluminium smelter pot rooms using Søderberg or Prebake anode technologies. The hydrogen fluoride and the aerosol concentration data measured during different work operations are plotted and evaluated applying the synchronised videos and air concentrations measured by the spectrometers. The main point-emission sources of HF and PM10 were identified and assessed. The major finding in the study was that the main source of PM10 and HF was partly open cells in a Søderberg pot room, whereas in a Prebake pot room, the point emissions of the two contaminants were associated with hot bath residues and hot replaced anodes. In order to prevent the simultaneous exposure to HF and PM10 among pot room workers it is important to prevent workers from being close to these point-sources under unfavourable ventilation. Storage of hot residues outside electrolytic cells without any point source ventilation should not occur. PMID:24622938

Skaugset, Nils Petter; Berlinger, Balázs; Radziuk, Bernhard; Tørring, Håvard; Synnes, Ole; Thomassen, Yngvar

2014-04-22

290

Short-time exposure to mono-n-butyl phthalate (MBP)-induced oxidative stress associated with DNA damage and the atrophy of the testis in pubertal rats.  

PubMed

Phthalates are widely used as plasticizer in various consumer domestic products and are known to disturb the male reproductive function in rodents. This study investigated the involvement of oxidative stress and the atrophy of the testes in pubertal rats exposed to mono-n-butyl phthalate (MBP). Four-week-old pubertal male rats were separated into three groups. In group I, 21 rats were fed rat chow containing 2 % MBP for 3 days. In group II, 21 rats were fed rat chow containing 2 % MBP for 3 days and antioxidant vitamins C (250 mg/kg/day) and E (50 mg/kg/day) were injected daily. In group III, 21 rats were fed standard rat chow and used as controls. After 3 days, each testis was weighed and the germ cell development was evaluated using the Johnsen score. The urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were measured as a biological marker of oxidative DNA damage. The mean testis weight was significantly lower for group I than groups II or III (p?time exposure to MBP may therefore induce oxidative DNA damage in rat testes, while antioxidant vitamins administered during exposure may protect against this stress. PMID:24310901

Shono, Takeshi; Taguchi, Tomoaki

2014-02-01

291

Evaluation and validation of housekeeping genes in response to ionizing radiation and chemical exposure for normalizing RNA expression in real-time PCR.  

PubMed

Gene expression changes are used with increasing frequency to assess the effects of exposure to environmental agents. Housekeeping (Hk) genes are essential in these analyses as internal controls for normalizing expression levels evaluated with Real-Time PCR (RT-PCR). Ideal Hk genes are constitutively expressed, do not respond to external stimuli and exhibit little or no sample-to-sample or run-to-run variation. Previous studies indicate that some commonly used Hk genes including glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and beta-actin have differential expression in various cell lines. Here we examine the expression of 11 Hk genes in four normal human lymphoblastoid cell lines and one T-cell leukemia (Jurkat) cell line following exposure to graded doses of ionizing radiation or to varying ratio concentrations of phytohemagglutinin (PHA) and phorbol myristate acetate (PMA). PHA and PMA are known to have synergistic effects on the expression of some genes and have very different effects from those of radiation. There has been no systematic study performed to ascertain the best control genes for radiation and/or PHA/PMA exposures in lymphoblastoid cells. Using a two-step reverse-transcriptase RT-PCR protocol we show that following radiation doses ranging from 0 to 400 cGy, 18S rRNA, acidic ribosomal protein, beta-actin, cyclophilin, GAPDH, phosphoglycerokinase, beta-2 microglobulin (B2M), beta-glucuronidase, hypoxanthine phosphoribosyltransferase and transferrin receptor showed no significant variation in expression in normal lymphoblastoid cells. In contrast, only 18S rRNA levels were unchanged in Jurkat cells. After PHA/PMA treatment of the same normal cell lines, B2M showed no significant variation and 18S rRNA, GAPDH and transcription binding protein (TBP) were minimally responsive, whereas in Jurkat cells all these genes were unresponsive. While our results suggest that the utility of a particular Hk gene should be determined for each experimental condition, 18S rRNA and B2M appear to be excellent candidates for use as internal controls in RT-PCR in human lymphoblastoid cells because they have the most constant levels of expression across cell lines following exposure to ionizing radiation as well as to PHA/PMA. PMID:17904413

Banda, Malathi; Bommineni, Aryamani; Thomas, Robert A; Luckinbill, Leo S; Tucker, James D

2008-01-01

292

Real-time and integrated measurement of potential human exposure to particle-bound polycyclic aromatic hydrocarbons (PAHs) from aircraft exhaust.  

PubMed

We used real-time monitors and low-volume air samplers to measure the potential human exposure to airborne polycyclic aromatic hydrocarbon (PAH) concentrations during various flight-related and ground-support activities of C-130H aircraft at an Air National Guard base. We used three types of photoelectric aerosol sensors (PASs) to measure real-time concentrations of particle-bound PAHs in a break room, downwind from a C-130H aircraft during a four-engine run-up test, in a maintenance hangar, in a C-130H aircraft cargo bay during cargo-drop training, downwind from aerospace ground equipment (AGE), and in a C-130H aircraft cargo bay during engine running on/off (ERO) loading and backup exercises. Two low-volume air samplers were collocated with the real-time monitors for all monitoring events except those in the break room and during in-flight activities. Total PAH concentrations in the integrated-air samples followed a general trend: downwind from two AGE units > ERO-loading exercise > four-engine run-up test > maintenance hangar during taxi and takeoff > background measurements in maintenance hangar. Each PAH profile was dominated by naphthalene, the alkyl-substituted naphthalenes, and other PAHs expected to be in the vapor phase. We also found particle-bound PAHs, such as fluoranthene, pyrene, and benzo[a]pyrene in some of the sample extracts. During flight-related exercises, total PAH concentrations in the integrated-air samples were 10-25 times higher than those commonly found in ambient air. Real-time monitor mean responses generally followed the integrated-air sample trends. These monitors provided a semiquantitative temporal profile of ambient PAH concentrations and showed that PAH concentrations can fluctuate rapidly from a baseline level < 20 to > 4,000 ng/m(3) during flight-related activities. Small handheld models of the PAS monitors exhibited potential for assessing incidental personal exposure to particle-bound PAHs in engine exhaust and for serving as a real-time dosimeter to indicate when respiratory protection is advisable. PMID:11017890

Childers, J W; Witherspoon, C L; Smith, L B; Pleil, J D

2000-09-01

293

Time-Course of Changes in Inflammatory Response after Whole-Body Cryotherapy Multi Exposures following Severe Exercise  

PubMed Central

The objectives of the present investigation was to analyze the effect of two different recovery modalities on classical markers of exercise-induced muscle damage (EIMD) and inflammation obtained after a simulated trail running race. Endurance trained males (n?=?11) completed two experimental trials separated by 1 month in a randomized crossover design; one trial involved passive recovery (PAS), the other a specific whole body cryotherapy (WBC) for 96 h post-exercise (repeated each day). For each trial, subjects performed a 48 min running treadmill exercise followed by PAS or WBC. The Interleukin (IL) -1 (IL-1), IL-6, IL-10, tumor necrosis factor alpha (TNF-?), protein C-reactive (CRP) and white blood cells count were measured at rest, immediately post-exercise, and at 24, 48, 72, 96 h in post-exercise recovery. A significant time effect was observed to characterize an inflammatory state (Pre vs. Post) following the exercise bout in all conditions (p<0.05). Indeed, IL-1? (Post 1 h) and CRP (Post 24 h) levels decreased and IL-1ra (Post 1 h) increased following WBC when compared to PAS. In WBC condition (p<0.05), TNF-?, IL-10 and IL-6 remain unchanged compared to PAS condition. Overall, the results indicated that the WBC was effective in reducing the inflammatory process. These results may be explained by vasoconstriction at muscular level, and both the decrease in cytokines activity pro-inflammatory, and increase in cytokines anti-inflammatory.

Pournot, Herve; Bieuzen, Francois; Louis, Julien; Fillard, Jean-Robert; Barbiche, Etienne; Hausswirth, Christophe

2011-01-01

294

Impairment of Rat Fetal Beta-Cell Development by Maternal Exposure to Dexamethasone during Different Time-Windows  

PubMed Central

Aim Glucocorticoids (GCs) take part in the direct control of cell lineage during the late phase of pancreas development when endocrine and exocrine cell differentiation occurs. However, other tissues such as the vasculature exert a critical role before that phase. This study aims to investigate the consequences of overexposure to exogenous glucocorticoids during different time-windows of gestation for the development of the fetal endocrine pancreas. Methods Pregnant Wistar rats received dexamethasone acetate in their drinking water (1 µg/ml) during the last week or throughout gestation. Fetuses and their pancreases were analyzed at day 15 and 21 of gestation. Morphometrical analysis was performed on pancreatic sections after immunohistochemistry techniques and insulin secretion was evaluated on fetal islets collected in vitro. Results Dexamethasone given the last week or throughout gestation reduced the beta-cell mass in 21-day-old fetuses by respectively 18% or 62%. This was accompanied by a defect in insulin secretion. The alpha-cell mass was reduced similarly. Neither islet vascularization nor beta-cell proliferation was affected when dexamethasone was administered during the last week, which was however the case when given throughout gestation. When given from the beginning of gestation, dexamethasone reduced the number of cells expressing the early marker of endocrine lineage neurogenin-3 when analyzed at 15 days of fetal age. Conclusions GCs reduce the beta- and alpha-cell mass by different mechanisms according to the stage of development during which the treatment was applied. In fetuses exposed to glucocorticoids the last week of gestation only, beta-cell mass is reduced due to impairment of beta-cell commitment, whereas in fetuses exposed throughout gestation, islet vascularization and lower beta-cell proliferation are involved as well, amplifying the reduction of the endocrine mass.

Dumortier, Olivier; Theys, Nicolas; Ahn, Marie-Therese; Remacle, Claude; Reusens, Brigitte

2011-01-01

295

10Be exposure dating of onset and timing of Neoglacial glacier advances in the Ecrins massif, French Alps  

NASA Astrophysics Data System (ADS)

Alpine glaciers are known to be highly sensitive to change in temperature and precipitation on decadal to centennial time scales. For two decades, numerous studies on Holocene climate revealed a period marked by abrupt cold reversals (e.g. 8.2 ka event) with increasing frequency and magnitude after the Holocene Climatic Optimum, during the so-called Neoglacial period (roughly the last 4 ka). State-of-the-art studies indicate that largest alpine glaciers failed to exceed their Little Ice Age (LIA) extent during these LIA Type-Events, unlike certain smaller glaciers. In the French Alps, very few investigations were conducted to date on Holocene glacier variability. Almost all studies focused on the most glacierized area: the Mont Blanc massif, where suitable organic remains to apply radiocarbon dating and dendrochronology are available. Other glacierized massifs are poorly studied, without any Holocene/Neoglacial glacier chronology up to now. Here, we present the results of a study focusing on six glacier forefields distributed in the Ecrins massif. Detailed geomorphological mapping and in-situ produced 10Be dating were carried on multi-crested so-called "LIA composite moraines". The targeted ridges are located in distal position with respect to late LIA drift in order to identify Holocene cold pulses that have led to (or slightly exceeded) LIA-like glacier extent. The 35 10Be ages obtained revealed that the onset of Neoglacial occurred at ~4.2 ka, and that at least two other advances were recorded at ~3.3 ka and ~0.85 ka. One site has yielded a nearly complete Neoglacial record as four discrete events have been dated. These results highlight the potential of lateral moraine ridge stratigraphy which could yield accurate record when sufficiently preserved, but also the different preservation of landforms along the glacier margin which could censor the record.

Le Roy, Melaine; Deline, Philip; Carcaillet, Julien

2013-04-01

296

Virtual reality exposure therapy  

PubMed Central

It has been proposed that virtual reality (VR) exposure may be an alternative to standard in vivo exposure. Virtual reality integrates real-time computer graphics, body tracking devices, visual displays, and other sensory input devices to immerse a participant in a computer- generated virtual environment. Virtual reality exposure is potentially an efficient and cost-effective treatment of anxiety disorders. VR exposure therapy reduced the fear of heights in the first controlled study of virtual reality in treatment of a psychiatric disorder. A case study supported the efficacy of VR exposure therapy for the fear of flying. The potential for virtual reality exposure treatment for these and other disorders is explored, and therapeutic issues surrounding the delivery of VR exposure are discussed.

Rothbaum, BO; Hodges, L; Kooper, R

1997-01-01

297

Virtual reality exposure therapy.  

PubMed

It has been proposed that virtual reality (VR) exposure may be an alternative to standard in vivo exposure. Virtual reality integrates real-time computer graphics, body tracking devices, visual displays, and other sensory input devices to immerse a participant in a computer-generated virtual environment. Virtual reality exposure is potentially an efficient and cost-effective treatment of anxiety disorders. VR exposure therapy reduced the fear of heights in the first controlled study of virtual reality in treatment of a psychiatric disorder. A case study supported the efficacy of VR exposure therapy for the fear of flying. The potential for virtual reality exposure treatment for these and other disorders is explored, and therapeutic issues surrounding the delivery of VR exposure are discussed. PMID:9185067

Rothbaum, B O; Hodges, L; Kooper, R

1997-01-01

298

Use of microarray technology to assess the time course of liver stress response after confinement exposure in gilthead sea bream (Sparus aurata L.)  

PubMed Central

Background Selection programs for growth and stress traits in cultured fish are fundamental to the improvement of aquaculture production. The gilthead sea bream (Sparus aurata) is the main aquacultured species in the Mediterranean area and there is considerable interest in the genetic improvement of this species. With the aim of increasing the genomic resources in gilthead sea bream and identifying genes and mechanisms underlying the physiology of the stress response, we developed a cDNA microarray for gilthead sea bream that is enriched by suppression substractive hybridization with stress and immunorelevant genes. This microarray is used to analyze the dynamics of gilthead sea bream liver expression profile after confinement exposure. Results Groups of confined and control juvenile fish were sampled at 6, 24, 72 and 120 h post exposure. GeneSpring analyses identified 202 annotated genes that appeared differentially expressed at least at one sampling time (P < 0.05). Gene expression results were validated by quantitative PCR of 10 target genes, and K-means clustering of differently expressed genes identified four major temporal gene expression profiles. Set 1 encompassed a rapid metabolic readjustment with enhanced uptake and intracellular transport of fatty acids as metabolic fuels. Set 2 was associated with a wide variety of tissue repair and remodeling processes that were mostly mediated by the stress response of the endoplasmic reticulum (ER). Sets 3 and 4 encompassed the re-establishment of cellular homeostasis with increased intracellular trafficking and scavenging of reactive oxygen species (ROS), accompanied by a bidirectional regulation of the immune system and a general decline of ROS production. Conclusions Collectively, these findings show the complex nature of the adaptive stress response with a clear indication that the ER is an important control point for homeostatic adjustments. The study also identifies metabolic pathways which could be analyzed in greater detail to provide new insights regarding the transcriptional regulation of the stress response in fish.

2010-01-01

299

MODEL DEVELOPMENT - EXPOSURE MODELS  

EPA Science Inventory

Humans are exposed to mixtures of chemicals from multiple pathways and routes. These exposures may result from a single event or may accumulate over time if multiple exposure events occur. The traditional approach of assessing risk from a single chemical and a single route of e...

300

Personal radiofrequency electromagnetic field measurements in The Netherlands: exposure level and variability for everyday activities, times of day and types of area.  

PubMed

Knowledge of the exposure to radiofrequency electromagnetic fields is necessary for epidemiological studies on possible health effects. The main goal of this study is to determine the exposure level and spatial and temporal variances during 39 everyday activities in 12 frequency bands used in mobile telecommunication and broadcasting. Therefore, 24 h measurements were gathered from 98 volunteers living in or near Amsterdam and Purmerend, The Netherlands. They carried an activity diary to be kept to the minute, a GPS logger sampling at an interval of 1 s, and an EME Spy exposimeter with a detection limit of 0.0066 mW/m(2) sampling at an interval of 10s in 12 frequency bands. The mean exposure over 24 h, excluding own mobile phone use, was 0.180 mW/m(2). During daytime exposure was about the same, but during night it was about half, and in the evening it was about twice as high. The main contribution to environmental exposure (calling by participant not included) is from calling with mobile phones (37.5%), from cordless DECT phones and their docking stations (31.7%), and from the base stations (12.7%). The exposure to mobile phone base stations increases with the percentage of urban ground use, which is an indication for high people density. In agreement, the highest mean exposure relates to the activities with high people density, such as travelling by public transport, visiting social events, pubs or shopping malls. Exposure at home depends mainly on exposure from people calling in the neighbourhood of the participant and thus on the number of persons in a household. In addition just the possession of DECT docking stations leads to exposure as most models transmit continuously in stand-by. Also wireless internet routers continuously transmit in the WiFi band. Though the highest exposure peaks in the WiFi band, up to 0.265 W/m(2), come from stray radiation of microwave ovens. The mean total exposure largely depends on phone calls of a high exposure level and short duration. These calls lead to potentially high contrasts as well in exposure levels between sessions of the same activity as between persons, thus posing a challenge for personal exposure prediction. PMID:22906414

Bolte, John F B; Eikelboom, Tessa

2012-11-01

301

Design, Characterization, and Optimization of a Broadband Mini Exposure Chamber for Studying Catecholamine Release From Chromaffin Cells Exposed to Microwave Radiation: Finite-Difference Time-Domain Technique  

Microsoft Academic Search

A free-space in vitro exposure system for identifying specific microwave (MW) parameters in the frequency range of 1-6 GHz that can induce nonthermal effects on exocytosis, which is the process by which neurotransmitter release occurs, has been designed, constructed, characterized, and optimized. The exposure system is placed within an anechoic chamber and incorporates continuous online monitoring of basal and stimulated

Jihwan Yoon; I. Chatterjee; D. McPherson; G. L. Craviso

2006-01-01

302

Influence of exposure and infusion times on the cytotoxicity and pharmacokinetics of cis - malonato[(4R, 5R )-4,5-bis(aminomethyl)- 2-isopropyl-1,3-dioxolane]platinum(II)  

Microsoft Academic Search

The effect of exposure time on the in vitro cytotoxicity of a new platinum complex, cis-malonato- [(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]platinum(II) (SKI 2053R) and cisplatin (CDDP) toward two human lung-adenocarcinoma\\u000a cell lines (PC-9, PC-14) and two human stomach-adenocarcinoma cell lines (KATO III, MKN-45) was investigated by variation\\u000a of the exposure time (1, 4, 12, and 24?h) and drug concentration to yield a constant product

Hun-Taek Kim; D.-K. Kim; Yong-Baik Cho; Taek-Soo Kim; I. Jung; Key H. Kim; Dae Seog Heo; Yung-Jue Bang; Sang-Goo Shin; Noe Kyeong Kim

1997-01-01

303

Insecticide Exposure in Parkinsonism.  

National Technical Information Service (NTIS)

Behavioral, neurochemical, and immunocytochemical studies characterized the possible role of insecticide exposure in the etiology of Parkinson's disease as it may relate to Gulf War Syndrome. Chlorpyrifos (CP) and permethrin (PM) were given 3 times over a...

J. R. Bloomquist

2002-01-01

304

Effects of Prenatal Exposure to a Low Dose Atrazine Metabolite Mixture on pubertal timing and prostrate Development of Male Long Evans Rats.  

EPA Science Inventory

The present study examines the postnatal reproductive development of male rats following prenatal exposure to an atrazine metabolite mixture (AMM) consisting of the herbicide atrazine and its environmental metabolites diaminochlorotriazine, hydroxyatrazine, deethylatrazine, and d...

305

DEVELOPMENT OF REAL-TIME SITE-SPECIFIC MICROSCALE EMISSION FACTOR MODEL FOR THE ASSESSMENT OF HUMAN EXPOSURE TO MOTOR VEHICLE EMISSIONS  

EPA Science Inventory

The United States Environmental Protection Agency's (EPA) National Expsoure Research Laboratory (NERL) has initiated a project to improve the methodology for modeling urban-scale human exposure to mobile source emissions. The modeling project has started by considering the nee...

306

Radiation exposure during ureteroscopy  

SciTech Connect

Use of fluoroscopy during ureteroscopy increases the risk of radiation exposure to the urologist and patient. Radiation entrance dosages were measured at skin level in 37 patients, and at the neck, trunk and finger of the urologist, and neck and trunk of the circulating nurse. Radiation exposure time was measured in 79 patients, and was related to the purpose of the procedure and the type of ureteroscope used, whether rigid or flexible. Exposure could be minimized by decreasing the fluoroscopy time. A portable C-arm fluoroscopy unit with electronic imaging and last image hold mode should be used to minimize exposure time. Lead aprons and thyroid shields should be used by the urologist and other personnel in the endoscopy room.

Bagley, D.H.; Cubler-Goodman, A. (Thomas Jefferson Univ., Philadelphia, PA (USA))

1990-12-01

307

HUMAN EXPOSURE ASSESSMENT USING IMMUNOASSAY  

EPA Science Inventory

The National Exposure Research Laboratory-Las Vegas is developing analytical methods for human exposure assessment studies. Critical exposure studies generate a large number of samples which must be analyzed in a reliable, cost-effective and timely manner. TCP (3,5,6-trichlor...

308

Inter-laboratory study of short time exposure (STE) test for predicting eye irritation potential of chemicals and correspondence to globally harmonized system (GHS) classification.  

PubMed

Short time exposure (STE) test using rabbit corneal cell line (SIRC) cells was developed as an alternative eye irritation test. STE test uses relative viability as the endpoint after cells are exposed to the test material at constant concentrations for 5 min. In this inter-laboratory study with 3 laboratories, 44 chemicals with a wide range of classes were evaluated for the transferability, between-lab reproducibility and predictive capacity of the STE test as an alternative eye irritation test. Globally harmonized system (GHS) classification based on Draize eye irritation test data was used as the comparative in vivo data. Transferability was assessed using standard chemicals (sodium lauryl sulfate, calcium thioglycolate, and Tween 80) and the coefficient variations (CVs) of relative viabilities between 3 labs were less than 0.13. The irritation category (Irritant or Non irritant) at each test concentration (5% and 0.05%) in STE test was the same in 3 laboratories for all 44 tested chemicals. The predictive capacity irritation category classification between STE test and GHS were compared, and a good correlation was confirmed (accuracy was 90.9% at all laboratories). In addition, the STE rankings of 1, 2, and 3 classified by the prediction model (PM) based on the relative viability at two concentrations (5% and 0.05%) were highly correlated with the GHS ranks of non-irritant, category 1, and category 2, respectively (accuracy was 75.0% at all laboratories). These results suggest that the STE test possessed easy transferability, reproducibility, good predictive performance. PMID:19952497

Takahashi, Yutaka; Hayashi, Takumi; Watanabe, Shinichi; Hayashi, Kazuhiko; Koike, Mirei; Aisawa, Noriko; Ebata, Shinya; Sakaguchi, Hitoshi; Nakamura, Tsuneaki; Kuwahara, Hirofumi; Nishiyama, Naohiro

2009-12-01

309

Advanced Exposure Metrics For Chemical Risk Analysis: Systems Biology and 'Omic-based Biomarkers for Exposure Reconstruction  

EPA Science Inventory

Direct measurement of human exposure to environmental contaminants in real time (when the exposure is actually occurring) is rare and difficult to obtain. This frustrates both exposure assessments and investigations into the linkage between chemical exposure and human disease. ...

310

Methods for analyzing occupational cohort data with application to lung cancer in US uranium miners: Techniques for fitting and checking exposure-time-response models  

SciTech Connect

Two methods were used to examine how lung cancer death rates vary with cumulative exposures to radiation and tobacco among uranium miners. The two methods produced similar results when death rate ratios were taken to be the product of radiation and tobacco effects. The estimates were discrepant when death rate ratios were taken to be the sum of radiation and tobacco effects. Both methods indicated better fit for the multiplicative model. It may be that cumulative exposures are inappropriate measures of the effects of radiation and tobacco on lung cancer death rates, as well as for other pollutants where the assumption of cumulative dose is the basis for risk assessments.

Halpern, J.; Whittemore, A.S.

1987-01-01

311

Different Patterns of Regional Purkinje Cell Loss in the Cerebellar Vermis as a Function of the Timing of Prenatal Ethanol Exposure in an Ovine Model  

PubMed Central

Studies in rat models of fetal alcohol spectrum disorders have indicated that the cerebellum is particularly vulnerable to ethanol-induced Purkinje cell loss during the third trimester-equivalent, with striking regional differences in vulnerability in which early-maturing regions in the vermis show significantly more loss than the late-maturing regions. The current study tested the hypothesis that the sheep model will show similar regional differences in fetal cerebellar Purkinje cell loss when prenatal binge ethanol exposure is restricted to the prenatal period of brain development equivalent to the third trimester and also compared the pattern of loss to that produced by exposure during the first trimester-equivalent. Pregnant Suffolk sheep were assigned to four groups: first trimester-equivalent saline control group, first trimester-equivalent ethanol group (1.75 g/kg/day), third trimester-equivalent saline control group, and third trimester-equivalent ethanol group (1.75 g/kg/day). Ethanol was administered as an intravenous infusion on 3 consecutive days followed by a 4-day ethanol-free interval, to mimic a weekend binge drinking pattern. Animals from all four groups were sacrificed and fetal brains were harvested on gestation day 133. Fetal cerebellar Purkinje cell counts were performed in an early-maturing region (lobules I-X) and a late-maturing region (lobules VIc-VII) from mid-sagittal sections of the cerebellar vermis. As predicted, the third trimester-equivalent ethanol exposure caused a significant reduction in the fetal cerebellar Purkinje cell volume density and Purkinje cell number in the early-maturing region, but not in the late-maturing region. In contrast, the first trimester-equivalent ethanol exposure resulted in significant reductions in both the early and late-maturing regions. These data confirmed the previous findings in rat models that third trimester-equivalent prenatal ethanol exposure resulted in regionally-specific Purkinje cell loss in the early-maturing region of the vermis, and further demonstrated that first trimester ethanol exposure caused more generalized fetal cerebellar Purkinje cell loss, independent of the cerebellar vermal region. These findings support the idea that prenatal ethanol exposure in the first trimester interferes with the genesis of Purkinje cells in an unselective manner, whereas exposure during the third trimester selectively kills post-mitotic Purkinje cells in specific vermal regions during a vulnerable period of differentiation and synaptogenesis.

Sawant, Onkar B.; Lunde, Emilie R.; Washburn, Shannon E.; Chen, Wei-Jung A.; Goodlett, Charles R.; Cudd, Timothy A.

2012-01-01

312

Relative-risk-estimate bias and loss of power in the Mantel test for trend resulting from the use of magnetic-field point-in-time (spot) measurements in epidemiological studies based on an ordinal exposure scale  

SciTech Connect

We assessed the merits of various point-in-time (spot) measurement protocols in case-control studies based on an ordinal exposure scale. After classifying a number of houses on the basis of prolonged monitoring of the ambient, extremely low frequency (ELF) magnetic field, we determined the probability of misclassification for each spot measurement protocol. We calculated the effect of this misclassification on the relative risk estimates and on the Mantel test for trend. We found that classification based on a small group of point-in-time measurements allows an adequate estimate of the relative risk, although the statistical significance of the dose-response gradient may be seriously underestimated. However, the use of automated ambient-field monitors, which results in loss of information on spatial variability, can lead to similar consequences. Therefore, manually collected point-in-time measurements remain a viable option for exposure assessment.

Delpizzo, V.; Salzberg, M.R. (Australian Radiation Laboratory, Yallambie, Victoria (Australia))

1992-01-01

313

Occupational exposure in MRI  

PubMed Central

This article reviews occupational exposure in clinical MRI; it specifically considers units of exposure, basic physical interactions, health effects, guideline limits, dosimetry, results of exposure surveys, calculation of induced fields and the status of the European Physical Agents Directive. Electromagnetic field exposure in MRI from the static field B0, imaging gradients and radiofrequency transmission fields induces electric fields and currents in tissue, which are responsible for various acute sensory effects. The underlying theory and its application to the formulation of incident and induced field limits are presented. The recent International Commission on Non-Ionizing Radiation Protection (ICNIRP) Bundesministerium für Arbeit und Soziales and Institute of Electrical and Electronics Engineers limits for incident field exposure are interpreted in a manner applicable to MRI. Field measurements show that exposure from movement within the B0 fringe field can exceed ICNIRP reference levels within 0.5 m of the bore entrance. Rate of change of field dB/dt from the imaging gradients is unlikely to exceed the new limits, although incident field limits can be exceeded for radiofrequency (RF) exposure within 0.2–0.5 m of the bore entrance. Dosimetric surveys of routine clinical practice show that staff are exposed to peak values of 42±24% of B0, with time-averaged exposures of 5.2±2.8 mT for magnets in the range 0.6–4 T. Exposure to time-varying fields arising from movement within the B0 fringe resulted in peak dB/dt of approximately 2 T s?1. Modelling of induced electric fields from the imaging gradients shows that ICNIRP-induced field limits are unlikely to be exceeded in most situations; however, movement through the static field may still present a problem. The likely application of the limits is discussed with respect to the reformulation of the European Union (EU) directive and its possible implications for MRI.

Mcrobbie, D W

2012-01-01

314

ASSESSING ASTHMATIC CHILDREN'S EXPOSURES TO TOXIC AIR POLLUTANTS AND THE POTENTIAL INHALED DOSES USING TIME ACTIVITY INFORMATION AND ENERGY EXPENDITURE DATA  

EPA Science Inventory

Accurately quantifying human exposures and the potential doses of various populations to environmental pollutants is critical for the U.S. Environmental Protection Agency to assess and manage human health risks. The Tampa Asthmatic Children's Study (TACS) was a pilot research stu...

315

Social Competence in Children at Risk Due to Prenatal Cocaine Exposure: Continuity over Time and Associations with Cognitive and Language Abilities  

ERIC Educational Resources Information Center

The continuity of social competence between 36 months and first grade was examined in a sample of children at risk due to prenatal exposure to cocaine (N = 92). Parent report data on social competence were collected at 36 months of age and both parent and teacher report data were collected when children were in first grade. Regression analyses…

Acra, C. Francoise; Bono, Katherine E.; Mundy, Peter C.; Scott, Keith G.

2009-01-01

316

Altered gene expression by low-dose arsenic exposure in humans and cultured cardiomyocytes: Assessment by real-time PCR array  

EPA Science Inventory

Arsenic contamination in drinking water has become a great public health concern worldwide. Chronic arsenic exposure results in higher risk of skin, lung and bladder cancer, as well as cardiovascular disease and diabetes. The purpose of this study was to investigate the effects o...

317

Turbulent times: effects of turbulence and violence exposure in adolescence on high school completion, health risk behavior, and mental health in young adulthood.  

PubMed

Turbulent social environments are associated with health and developmental risk, yet mechanisms have been understudied. Guided by a life course framework and stress theory, this study examined the association between turbulent life transitions (including frequent residential mobility, school transitions, family structure disruptions, and homelessness) and exposure to violence during adolescence and high school completion, mental health, and health risk behaviors in young adulthood. Participants (n = 4834) from the U.S. National Longitudinal Survey of Youth, 1997 cohort were followed prospectively from age 12-14 years for 10 years. We used structural equation models to investigate pathways between turbulence and cumulative exposure to violence (CEV), and high school completion, mental health, and health risk behaviors, while accounting for early life socio-demographics, family processes, and individual characteristics. Results indicated that turbulence index was associated with cumulative exposure to violence in adolescence. Both turbulence index and cumulative exposure to violence were positively associated with higher health risk behavior, poorer mental health, and inversely associated with high school completion. These findings highlight the importance of considering the cumulative impact of turbulent and adverse social environments when developing interventions to optimize health and developmental trajectory for adolescents transitioning into adulthood. PMID:23063217

Boynton-Jarrett, Renée; Hair, Elizabeth; Zuckerman, Barry

2013-10-01

318

Effects of prenatal exposure to a low dose atrazine metabolite mixture onpubertal timing and prostate development of male Long-Evans rats  

EPA Science Inventory

Atrazine (ATR) is a chlorotriazine herbicide extensively used in the US and other countries. Studies examining the effects of adult or developmental ATR exposure on the mammary gland (MG) have used either the Sprague Dawley (SD) or Long-Evans (LE) rat, but no strain comparisons h...

319

Radiation Risk from Chronic Low Dose-Rate Radiation Exposures: The Role of Life-Time Animal Studies - Workshop October 2005  

SciTech Connect

As a part of Radiation research conference, a workshop was held on life-long exposure studies conducted in the course of irradiation experiements done at Argonne National Laboratory between 1952-1992. A recent review article documents many of the issues discussed at that workshop.

Gayle Woloschak

2009-12-16

320

Chemical Exposure  

MedlinePLUS Videos and Cool Tools

... 2014 Related MedlinePlus Pages Environmental Health Hormones Transcript Phthalates are a group of chemicals used to make ... the ban has helped lower exposure to some phthalates, while opening the door to others. Researchers looked ...

321

Climatic and topographic controls on the style and timing of Late Quaternary glaciation throughout Tibet and the Himalaya defined by 10Be cosmogenic radionuclide surface exposure dating  

USGS Publications Warehouse

Temporal and spatial changes in glacier cover throughout the Late Quaternary in Tibet and the bordering mountains are poorly defined because of the inaccessibility and vastness of the region, and the lack of numerical dating. To help reconstruct the timing and extent of glaciation throughout Tibet and the bordering mountains, we use geomorphic mapping and 10Be cosmogenic radionuclide (CRN) surface dating in study areas in southeastern (Gonga Shan), southern (Karola Pass) and central (Western Nyainqentanggulha Shan and Tanggula Shan) Tibet, and we compare these with recently determined numerical chronologies in other parts of the plateau and its borderlands. Each of the study regions receives its precipitation mainly during the south Asian summer monsoon when it falls as snow at high altitudes. Gonga Shan receives the most precipitation (>2000 mm a-1) while, near the margins of monsoon influence, the Karola Pass receives moderate amounts of precipitation (500-600 mm a-1) and, in the interior of the plateau, little precipitation falls on the western Nyainqentanggulha Shan (???300 mm a -1) and the Tanggula Shan (400-700 mm a-1). The higher precipitation values for the Tanggula Shan are due to strong orographic effects. In each region, at least three sets of moraines and associated landforms are preserved, providing evidence for multiple glaciations. The 10Be CRN surface exposure dating shows that the formation of moraines in Gonga Shan occurred during the early-mid Holocene, Neoglacial and Little Ice Age, on the Karola Pass during the Lateglacial, Early Holocene and Neoglacial, in the Nyainqentanggulha Shan date during the early part of the last glacial cycle, global Last Glacial Maximum and Lateglacial, and on the Tanggula Shan during the penultimate glacial cycle and the early part of the last glacial cycle. The oldest moraine succession in each of these regions varies from the early Holocene (Gonga Shan), Lateglacial (Karola Pass), early Last Glacial (western Nyainqentanggulha Shan), and penultimate glacial cycle (Tanggula Shan). We believe that the regional patterns and timing of glaciation reflect temporal and spatial variability in the south Asian monsoon and, in particular, in regional precipitation gradients. In zones of greater aridity, the extent of glaciation has become increasingly restricted throughout the Late Quaternary leading to the preservation of old (???100 ka) glacial landforms. In contrast, in regions that are very strongly influenced by the monsoon (???1600 mm a-1), the preservation potential of pre-Lateglacial moraine successions is generally extremely poor. This is possibly because Lateglacial and Holocene glacial advances may have been more extensive than early glaciations and hence may have destroyed any landform or sedimentary evidence of earlier glaciations. Furthermore, the intense denudation, mainly by fluvial and mass movement processes, which characterize these wetter environments, results in rapid erosion and re-sedimentation of glacial and associated landforms, which also contributes to their poor preservation potential. ?? 2004 Elsevier Ltd. All rights reserved.

Owen, L. A.; Finkel, R. C.; Barnard, P. L.; Haizhou, Ma.; Asahi, K.; Caffee, M. W.; Derbyshire, E.

2005-01-01

322

Exposure Time Calculations for Calibrating of Vega and G191-B2B in the Optical and Near-Infrared: Ground-based, Airborne, Balloon-based, and Rocket-borne Experiments  

NASA Astrophysics Data System (ADS)

For SNAP to succeed the science program requires an accuracy in supernova color determination over the wavelength range 0.35-1.7 microns of 2% in the optical and 3% in the near infrared. We explore the possibility of the spectrophotometric calibration of standard stars for SNAP mission in the optical and near infrared using 5 different programs. It is important to understand the impact of different calibration programs in the estimated exposure time calculation and the estimated signal to noise (SNR). We have calculated the exposure time required for imaging and spectroscopic observations of spectrophotometric standard stars (Vega and HST standard G191-B2B) using SNAP detectors and filters at specified seeing, airmass, and sky conditions at either ground/space bases.

Allam, S.; Bohlin, R. C.; Deustua, S. E.; Kent, S. M.; Lampton, M. L.; Mostek, N.; Mufson, S. L.; Richmond, M. W.; Smith, J. A.; Tucker, D. L.; Woodgate, B. E.; SNAP

2004-12-01

323

Mapping occupational heat exposure and effects in South-East Asia: ongoing time trends 1980-2011 and future estimates to 2050.  

PubMed

A feature of climate impacts on occupational health and safety are physiological limits to carrying out physical work at high heat exposure. Heat stress reduces a workers work capacity, leading to lower hourly labour productivity and economic output. We used existing weather station data and climate modeling grid cell data to describe heat conditions (calculated as Wet Bulb Globe Temperature, WBGT) in South-East Asia. During the hottest month in this region (March) afternoon WBGT levels are already high enough to cause major loss of hourly work capacity and by 2050 the situation will be extreme for many outdoor jobs. PMID:23411757

Kjellstrom, Tord; Lemke, Bruno; Otto, Matthias

2013-01-01

324

EXPOSURE ANALYSIS  

EPA Science Inventory

This proceedings chapter will discuss the state-of-the-science regarding the evaluation of exposure as it relates to water quality criteria (WQC), sediment quality guidelines (SQG), and wildlife criteria (WC). Throughout this discussion, attempts are made to identify the methods ...

325

Effects of prenatal exposure to a low dose atrazine metabolite mixture on pubertal timing and prostate development of male Long-Evans rats.  

PubMed

The present study examines the postnatal reproductive development of male rats following prenatal exposure to an atrazine metabolite mixture (AMM) consisting of the herbicide atrazine and its environmental metabolites diaminochlorotriazine, hydroxyatrazine, deethylatrazine, and deisopropylatrazine. Pregnant Long-Evans rats were treated by gavage with 0.09, 0.87, or 8.73mg AMM/kg body weight (BW), vehicle, or 100mg ATR/kg BW positive control, on gestation days 15-19. Preputial separation was significantly delayed in 0.87 mg and 8.73mg AMM-exposed males. AMM-exposed males demonstrated a significant treatment-related increase in incidence and severity of inflammation in the prostate on postnatal day (PND) 120. A dose-dependent increase in epididymal fat masses and prostate foci were grossly visible in AMM-exposed offspring. These results indicate that a short, late prenatal exposure to mixture of chlorotriazine metabolites can cause chronic prostatitis in male LE rats. The mode of action for these effects is presently unclear. PMID:20727709

Stanko, Jason P; Enoch, Rolondo R; Rayner, Jennifer L; Davis, Christine C; Wolf, Douglas C; Malarkey, David E; Fenton, Suzanne E

2010-12-01

326

Effects of prenatal exposure to a low dose atrazine metabolite mixture on pubertal timing and prostate development of male Long-Evans rats  

SciTech Connect

The present study examines the postnatal reproductive development of male rats following prenatal exposure to an atrazine metabolite mixture (AMM) consisting of the herbicide atrazine and its environmental metabolites diaminochlorotriazine, hydroxyatrazine, deethylatrazine, and deisopropylatrazine. Pregnant Long-Evans rats were treated by gavage with 0.09, 0.87, or 8.73 mg AMM/kg body weight (BW), vehicle, or 100 mg ATR/kg BW positive control, on gestation days 15 19. Preputial separation was significantly delayed in 0.87 mg and 8.73 mg AMM-exposed males. AMM-exposed males demonstrated a significant treatment-related increase in incidence and severity of inflammation in the prostate on postnatal day (PND) 120. A dose-dependent increase in epididymal fat masses and prostate foci were grossly visible in AMM-exposed offspring. These results indicate that a short, late prenatal exposure to mixture of chlorotriazine metabolites can cause chronic prostatitis in male LE rats. The mode of action for these effects is presently unclear.

Stanko, Jason [National Institute of Environmental Health Sciences (NIEHS); Enoch, Rolondo [North Carolina Central University, Durham; Rayner, Jennifer L [ORNL; Davis, Christine [U.S. Environmental Protection Agency; Wolf, Douglas [U.S. Environmental Protection Agency; Malarkey, David [University of North Carolina, Chapel Hill; Fenton, Suzanne [National Institute of Environmental Health Sciences (NIEHS)

2010-12-01

327

Altered Gene Expression by Low-Dose Arsenic Exposure in Humans and Cultured Cardiomyocytes: Assessment by Real-Time PCR Arrays  

PubMed Central

Chronic arsenic exposure results in higher risk of skin, lung, and bladder cancer, as well as cardiovascular disease and diabetes. The purpose of this study was to investigate the effects on expression of selected genes in the blood lymphocytes from 159 people exposed chronically to arsenic in their drinking water using a novel RT-PCR TaqMan low-density array (TLDA). We found that expression of tumor necrosis factor-? (TNF-?), which activates both inflammation and NF-?B-dependent survival pathways, was strongly associated with water and urinary arsenic levels. Expression of KCNA5, which encodes a potassium ion channel protein, was positively associated with water and toe nail arsenic levels. Expression of 2 and 11 genes were positively associated with nail and urinary arsenic, respectively. Because arsenic exposure has been reported to be associated with long QT intervals and vascular disease in humans, we also used this TLDA for analysis of gene expression in human cardiomyocytes exposed to arsenic in vitro. Expression of the ion-channel genes CACNA1, KCNH2, KCNQ1 and KCNE1 were down-regulated by 1-?M arsenic. Alteration of some common pathways, including those involved in oxidative stress, inflammatory signaling, and ion-channel function, may underlay the seemingly disparate array of arsenic-associated diseases, such as cancer, cardiovascular disease, and diabetes.

Mo, Jinyao; Xia, Yajuan; Wade, Timothy J.; DeMarini, David M.; Davidson, Mercy; Mumford, Judy

2011-01-01

328

On the microwave exposure.  

PubMed

During the last decades the use of microwaves has been common in the industry, medicine, household and armed forces. According to the literature microwaves may especially cause lens opacities and other serious health disturbances. The authors of this paper examined 121 radar workers, but nothing was found which could be connected to microwaves. For example, the amount of lens opacities had correlation only to the age of the patients, but not to the exposure time of microwaves. The exposure duration varied from 0 to 28 years and the age of the patients between 18 and 59 years. PMID:7158323

Castrén, J; Lauteala, L; Antere, E; Aho, J; Torvi, K

1982-08-01

329

Exposure to captan in fruit growing.  

PubMed

This study characterized occupational exposure to pesticides in fruit growing in The Netherlands to assess determinants of exposure. Large-scale exposure surveys were carried out during application of pesticides and during reentry activities. Data on contamination inside the fruit growers' homes were obtained, and total potential exposure for the fruit grower and his family during the growing and harvesting season was estimated. Repeated measurements on the same subject were collected to study components of exposure variability. Relative contribution of the respiratory route and different skin sites to total exposure were assessed. Captan was used as a marker for exposure. Inhalable dust exposure was measured with a personal monitor and potential dermal exposure with skin pads and hand rinsing. Dislodgeable foliar residue was measured by taking leaf punches. For respiratory exposure and potential dermal exposure, differences were observed between several tasks. Workers were categorized according to tasks performed depending on the exposure measure(s) (e.g., hands, forehead, inhalable dust) considered relevant for a specific study purpose. In general, within-worker variability of all exposure measurements was larger than between-worker variability. Variability in dermal exposure on the same body location was small relative to variability between different body locations. Differences in total exposure, including exposure inside the home, between the fruit grower and the son were small. Exposure of the wife was two to three times lower than for the fruit grower and the son. As exposure per unit of time was in the same order of magnitude for different tasks, individual time spent on these tasks is crucial for estimating total potential exposure. Repeated measurements are necessary to estimate individual exposure accurately because of the large within-worker variability. PMID:9530801

de Cock, J; Heederik, D; Kromhout, H; Boleij, J S; Hoek, F; Wegh, H; Tjoe Ny, E

1998-03-01

330

Exposure of the general population to gasoline.  

PubMed Central

This paper summarizes the currently available information on gasoline exposure to the general population. In general, the largest contribution to the time weighted exposures results from exposures while indoors, which are influenced by the outside air, indoor sources, and attached garages. Personal activities, including refueling and commuting, contribute significantly higher exposures but last for only a small portion of the 24-hr time weighted average. The highest exposed group includes those individuals living near large service stations and those with contaminated water supplies.

Akland, G G

1993-01-01

331

Time exposure studies on stress corrosion cracking of aluminum 2014-T6, aluminum 7075-T651, and titanium 6Al-4V  

NASA Technical Reports Server (NTRS)

The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 7075-T651 and titanium 6A1-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 6) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity). Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, a similar observation was not noted for titanium stressed specimens. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl); while they (both alloys) seem to resist stress corrosion cracking in methyl alcohol, ethyl alcohol, iso-propyl alcohol, and demineralized distilled water. Titanium 6A1-4V showed some evidence of susceptibility to SCC in methanol, while no such susceptibility was exhibited in ethanol, iso-propyl alcohol and demineralized distilled water.

Terrell, J.

1972-01-01

332

Time exposure studies on stress corrosion cracking of aluminum 2014-T6, 2219-T87, 2014-T651, 7075-T651, and titanium 6Al-4V  

NASA Technical Reports Server (NTRS)

The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 2219-T87, 2014-T651, 7075-T651 and titanium 6Al-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 7) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity), and demineralized distilled water. Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, titanium stressed specimens showed no reactions to its environment. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 and aluminum 2014-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl), while aluminum 2219-T87 seem to resist stress corrosion cracking in sodium chloride at three levels of stress (25%, 50%, and 75% Y.S.). In organic fluids of methyl, ethyl, and iso-propyl alcohol, 2014-T6 and 7075-T651 did not fail by SCC; but 2014-T651 was susceptible to SCC in methly alcohol, but resistant in ethyl alcohol, iso-propyl alcohol and demineralized distilled water.

Terrell, J.

1973-01-01

333

Criminal exposure.  

PubMed

In August, an HIV-positive man plead guilty to sexually assaulting a 14-year-old boy. The sleeping boy awoke to find [name removed] sexually assaulting him, while watching a pornographic video. [Name removed] plead guilty to the assault with intent to rape a child. In addition, [name removed] received three counts of indecent assault and battery on a child, and exposure of pornographic material to a minor. [Name removed] will remain on probation for five years, although the prosecution had recommended sentencing [name removed] to four or five years in prison. The boy continues to be tested for HIV. PMID:11366904

1999-09-01

334

[The regression time of heat-shock puffs in the polytene chromosomes of Drosophila melanogaster as a criterion for assessing the effect of different stress exposures].  

PubMed

The time of regression of heat shock puffs was studied in the polytene chromosomes of Drosophila melanogaster larvae of mutant stock (1(1)ts403, defective in heat shock protein (HSP) system, and of the wild type stock Canton S after heat shock (37 degrees C), after placing of larvae to anaerobic conditions (dipping into physiological solution), and after combination of these treatments. It is shown that the time of regression of heat shock puffs depends on the specificity of the treatment (heat shock or anaerobic conditions), its duration (13 or 30 min), or on the peculiarity of functioning of HSP system in the cells of different stock larvae. Our results are in accordance with the idea of the HSP genes expression autoregulation, and allow to use the heat shock puff regression time as a criterion for estimation of damaging effects of stress factors. PMID:7571018

Kutskova, Iu A; Mamon, L A

1995-01-01

335

Exposure control for HDR video  

NASA Astrophysics Data System (ADS)

This paper proposes an algorithm for determining the exposure times for High Dynamic Range (HDR) video by adapting them to the current lighting. Due to the limited capability of the sensor used, only two exposures per frame can be taken. For each image, the histogram for the exposure time of the other image is estimated. When this histogram is subtracted from the original, the result can be used to adjust the exposure time to the current lighting situation by standard exposure control algorithms. The subtraction removes the dynamic range already covered by the other image, thus the exposure time can be optimized for the residual dynamic range. The algorithm has been compared with state-of-the-art algorithms for HDR imaging. It is proven to have comparable results in mean squared error to a ground truth gained from real-world data. Furthermore this algorithm is capable of running during the capturing process of a video, since it doesn't require additional exposures than those already taken.

Bürker, M.; Rößing, C.; Lensch, H. P. A.

2014-05-01

336

Development and Application of a “Real Time” Lead-in-Air Analyzer in Controlling Lead Exposure at a Primary Lead Smelter  

Microsoft Academic Search

To assist in locating and quantifying fugitive emissions in a primary lead smelter, a “real time” lead-in-air analyzer has been developed. Dust is collected on paper tape filters and the lead analysed by X-ray fluorescence. The unit has been used successfully to assist in the implementation of an engineering control monitoring program.

W. J. SMITH; D. L. DEKKER; R. GREENWOOD-SMITH

1986-01-01

337

Climatic and topographic controls on the style and timing of Late Quaternary glaciation throughout Tibet and the Himalaya defined by 10Be cosmogenic radionuclide surface exposure dating  

Microsoft Academic Search

Temporal and spatial changes in glacier cover throughout the Late Quaternary in Tibet and the bordering mountains are poorly defined because of the inaccessibility and vastness of the region, and the lack of numerical dating. To help reconstruct the timing and extent of glaciation throughout Tibet and the bordering mountains, we use geomorphic mapping and 10Be cosmogenic radionuclide (CRN) surface

Lewis A. Owen; Robert C. Finkel; Patrick L. Barnard; Ma Haizhou; Katsuhiko Asahi; Marc W. Caffee; Edward Derbyshire

2005-01-01

338

Exposure to toxic environmental agents.  

PubMed

: Reducing exposure to toxic environmental agents is a critical area of intervention for obstetricians, gynecologists, and other reproductive health care professionals. Patient exposure to toxic environmental chemicals and other stressors is ubiquitous, and preconception and prenatal exposure to toxic environmental agents can have a profound and lasting effect on reproductive health across the life course. Prenatal exposure to certain chemicals has been documented to increase the risk of cancer in childhood; adult male exposure to pesticides is linked to altered semen quality, sterility, and prostate cancer; and postnatal exposure to some pesticides can interfere with all developmental stages of reproductive function in adult females, including puberty, menstruation and ovulation, fertility and fecundity, and menopause. Many environmental factors harmful to reproductive health disproportionately affect vulnerable and underserved populations, which leaves some populations, including underserved women, more vulnerable to adverse reproductive health effects than other populations. The evidence that links exposure to toxic environmental agents and adverse reproductive and developmental health outcomes is sufficiently robust, and the American College of Obstetricians and Gynecologists and the American Society for Reproductive Medicine join leading scientists and other clinical practitioners in calling for timely action to identify and reduce exposure to toxic environmental agents while addressing the consequences of such exposure. PMID:24084567

2013-10-01

339

Exposure to toxic environmental agents.  

PubMed

Reducing exposure to toxic environmental agents is a critical area of intervention for obstetricians, gynecologists, and other reproductive health care professionals. Patient exposure to toxic environmental chemicals and other stressors is ubiquitous, and preconception and prenatal exposure to toxic environmental agents can have a profound and lasting effect on reproductive health across the life course.Prenatal exposure to certain chemicals has been documented to increase the risk of cancer in childhood; adult male exposure to pesticides is linked to altered semen quality, sterility, and prostate cancer; and postnatal exposure to some pesticides can interfere with all developmental stages of reproductive function in adult females, including puberty, menstruation and ovulation, fertility and fecundity, and menopause. Many environmental factors harmful to reproductive health disproportionately affect vulnerable and underserved populations,which leaves some populations, including underserved women, more vulnerable to adverse reproductive health effects than other populations. The evidence that links exposure to toxic environmental agents and adverse reproductive and developmental health outcomes is sufficiently robust, and the American College of Obstetricians and Gynecologists and the American Society for Reproductive Medicine join leading scientists and other clinical practitioners in calling for timely action to identify and reduce exposure to toxic environmental agents while addressing the consequences of such exposure. PMID:24070500

2013-10-01

340

Diethylstilbestrol exposure.  

PubMed

Diethylstilbestrol is a synthetic nonsteroidal estrogen that was used to prevent miscarriage and other pregnancy complications between 1938 and 1971 in the United States. In 1971, the U.S. Food and Drug Administration issued a warning about the use of diethylstilbestrol during pregnancy after a relationship between exposure to this synthetic estrogen and the development of clear cell adenocarcinoma of the vagina and cervix was found in young women whose mothers had taken diethylstilbestrol while they were pregnant. Although diethylstilbestrol has not been given to pregnant women in the United States for more than 30 years, its effects continue to be seen. Women who took diethylstilbestrol during pregnancy have a slightly higher risk of breast cancer than the general population and therefore should be encouraged to have regular mammography. Women who were exposed to diethylstilbestrol in utero may have structural reproductive tract anomalies, an increased infertility rate, and poor pregnancy outcomes. However, the majority of these women have been able to deliver successfully. Recommendations for gynecologic examinations include vaginal and cervical digital palpation, which may provide the only evidence of clear cell adenocarcinoma. Initial colposcopic examination should be considered; if the findings are abnormal, colposcopy should be repeated annually. If the initial colposcopic examination is normal, annual cervical and vaginal cytology is recommended. Because of the higher risk of spontaneous abortion, ectopic pregnancy, and preterm delivery, obstetric consultation may be required for pregnant women who had in utero diethylstilbestrol exposure. The male offspring of women who took diethylstilbestrol during pregnancy have an increased incidence of genital abnormalities and a possibly increased risk of prostate and testicular cancer. Routine prostate cancer screening and testicular self-examination should be encouraged. PMID:15168959

Schrager, Sarina; Potter, Beth E

2004-05-15

341

The influence of time of maternal exposure to 2,4,5,2 prime ,4 prime ,5 prime -hexachlorobiphenyl on its accumulation in their nursing offspring  

Microsoft Academic Search

2,4,5,2',4',5'-Hexachlorobiphenyl (6-CB) is mobilized from rodent tissues during the lipid depletion associated with food restriction or lactation, the latter condition resulting in the substantial elimination of the maternal body burden of the chemical to nursing offspring. The present study was undertaken to determine whether the rate and\\/or magnitude of accumulation of 6-CB in nursing offspring differed with time following PCB

L. A. Gallenberg; B. J. Ring; M. J. Vodicnik

1990-01-01

342

Lead exposure at uncovered outdoor firing ranges  

Microsoft Academic Search

Excessive lead exposure in shooting instructors at indoor firing ranges and covered outdoor firing ranges has been documented. The City of Los Angeles assessed exposure of its full-time shooting instructors at uncovered outdoor ranges via air monitoring and blood lead-level measurements. Results of these tests revealed that significant lead exposure and absorption can occur at outdoor firing ranges. The use

Robert Leonard Goldberg; Anthony M. Hicks; L. M. OLeary; Stephanie London

1991-01-01

343

The missing pedicle: a radiodiagnostic challenge  

PubMed Central

The absence of a vertebral pedicle, regardless of location, always merits careful consideration. There are a variety of disease states in addition to intrinsic mechanisms which may influence the development of the spine and hence potentiate pedicular absence. Each of these diseases or processes must be considered when confronted by a missing pedicle. This paper will identify and briefly discuss the most common conditions resulting in pedicular absence. ImagesFigure 1Figure 2Figure 3Figure 4

McLaughlin, KJ; Kogon, PL

1989-01-01

344

Time interval from cigarette smoke exposure to blood donation and markers of inflammation: should a smoking cut-off be designated?  

PubMed

Allogeneic blood transfusion leads to the infusion into the recipient of large amounts of antigens that may create conditions which are related to immune system modulation. The aim of this study was to determine the effects of smoking habit on vascular endothelial growth factor (VEGF) and interleukin 6 (IL-6) levels in the plasma of blood donors. Blood samples from 170 consecutive blood donors was collected and analyzed for serum markers, while questionnaire data was collected. Serum cotinine levels were calculated for non-smokers, while serum cytokine IL-6 and VEGF concentrations were also calculated among 88 randomly selected subjects. Controlling for the donors age and gender, a strong tendency was found for smoking within 24 h of the blood donation to be associated with a higher VEGF concentration of the donated blood (ß = 141.13, p = 0.06), while the donor age was independently related to VEGF levels (p = 0.001). Additionally the IL-6 levels in the transfused blood were independently associated with the donors age (p = 0.001) and gender (p = 0.002) but not with their smoking status. Further research is needed so as to assess the need of updating blood donation guide lines to regulate the time intervals between the time from the last cigarette and blood donation. PMID:20602565

Symvoulakis, Emmanouil K; Vardavas, Constantine I; Fountouli, Popi; Stavroulaki, Aimilia; Antoniou, Katerina M; Duijker, George; Tzatzarakis, Manolis N; Sfiridaki, Katerina; Bolonaki, Eirini; Alegakis, Thanasis; Tsatsakis, Aristidis M

2010-09-01

345

Exposure chamber  

DOEpatents

A chamber for exposing animals, plants, or materials to air containing gases or aerosols is so constructed that catch pans for animal excrement, for example, serve to aid the uniform distribution of air throughout the chamber instead of constituting obstacles as has been the case in prior animal exposure chambers. The chamber comprises the usual imperforate top, bottom and side walls. Within the chamber, cages and their associated pans are arranged in two columns. The pans are spaced horizontally from the walls of the chamber in all directions. Corresponding pans of the two columns are also spaced horizontally from each other. Preferably the pans of one column are also spaced vertically from corresponding pans of the other column. Air is introduced into the top of the chamber and withdrawn from the bottom. The general flow of air is therefore vertical. The effect of the horizontal pans is based on the fact that a gas flowing past the edge of a flat plate that is perpendicular to the flow forms a wave on the upstream side of the plate. Air flows downwardly between the chamber walls and the outer edges of the pan. It also flows downwardly between the inner edges of the pans of the two columns. It has been found that when the air carries aerosol particles, these particles are substantially uniformly distributed throughout the chamber.

Moss, Owen R. (Kennewick, WA)

1980-01-01

346

59 FR- Disease Not Associated With Exposure to Certain Herbicide Agents  

Federal Register 2010, 2011, 2012, 2013

...that time, between exposure to herbicides containing...comparison group, determine exposure, evaluate clinical...1984. Human health effects of 2,4,5-T and...neuropathy and herbicide exposure outweighs the credible...Likewise, studies of exposures generally found...

1994-01-04

347

Age-associated alterations in the time-dependent profile of pro- and anti-inflammatory proteins within the hippocampus in response to acute exposure to interleukin-1?.  

PubMed

The pro-inflammatory cytokine IL-1? is known to play a role in several models of aging, neuroinflammation, and neurodegenerative diseases. Here, we document a detailed time- and age-dependent pattern of pro- and anti-inflammatory biomarkers following bilateral intrahippocampal injection of interleukin-1?. During the first 12h several pro- and anti-inflammatory cytokines increased in the aged (24 mo old) rats, some of which returned to baseline levels by 24h post-injection while others remained elevated for 72 h post-injection. In contrast, no such increases were observed in the young (3 mo old) rats. Interestingly, young rats up-regulated mRNA of two pro-inflammatory cytokines, interleukin-1? and tumor necrosis factor-?, but did not translate these transcripts into functional proteins, which may be related to expression of suppressor of cytokine signaling type-2. These results contribute to our understanding of how neuroinflammation may contribute to the pathogenesis of age-related neurodegenerative disorders due to an age-related bias towards a hyper-reactive immune response that is not selective for a pro- or anti-inflammatory phenotype following an inflammatory stimulus. PMID:24393520

Hopp, Sarah C; Royer, Sarah; Brothers, Holly M; Kaercher, Roxanne M; D'Angelo, Heather; Bardou, Isabelle; Wenk, Gary L

2014-02-15

348

Solar UVA exposures  

NASA Astrophysics Data System (ADS)

Exposures to UVA radiation (320 - 400 nm) have been linked to increasing the risk of skin cancer, premature skin photoageing and skin wrinkling. The relative proportion of the UVA irradiances in the solar spectrum changes with time of day and season. Material such as window glass found in offices, homes and motor vehicles acts as a barrier to the shorter solar UVB wavelengths (280 - 320 nm) and transmits some of the longer UVA wavelengths (dependent on the type of glass). As a result, the spectrum of the filtered UV transmitted through the material may be substantially different from that of the unfiltered solar UV spectrum. This results in a change in the relative ratio of UVA to UVB irradiances and a consequent change in the biologically damaging UV exposures. For these environments where the UVB wavelengths have been removed and the UVA wavelengths are still present, it is necessary to consider the erythemal irradiances due to these UVA wavelengths only. This paper investigates the times taken for an exposure of 1 SED (standard erythemal dose) due to the UVA wavelengths.

Parisi, Alfio V.; Kimlin, Michael G.

2005-08-01

349

Regression models for the effects of exposure rate and cumulative exposure.  

PubMed

Epidemiologic studies that collect detailed exposure histories often incorporate this information into a regression model through a time-dependent cumulative exposure metric. This summary metric obscures variations in exposure rates among people and within persons over time. To disentangle the effects of cumulative exposure and exposure rate, one standard approach is to simultaneously model both cumulative exposure and average exposure rate. We propose an alternative regression model that uses a person's detailed exposure history information to describe the effect of the history of exposure increments on the relative hazard function. We illustrate this approach using data from a cohort study of radon exposure and lung cancer mortality among uranium miners. Compared with a standard cumulative exposure-average exposure rate model, our proposed approach yielded somewhat stronger evidence that the radon-lung cancer mortality association is modified by exposure rate. At low exposure rates, the estimated excess relative hazard per 100 working-level months was 0.63 (95% confidence interval = 0.32-1.37) under the standard approach, whereas under the proposed approach it was 1.23 (0.53-3.76). The proposed approach may provide better understanding of relationships between a protracted exposure and disease and is readily implemented using existing statistical software. PMID:23007044

Richardson, David B; Cole, Stephen R; Langholz, Bryan

2012-11-01

350

An in vitro evaluation of effect of eugenol exposure time on the shear bond strength of two-step and one-step self-etching adhesives to dentin  

PubMed Central

Objectives: To evaluate the effect of the eugenol exposure time of an eugenol-based provisional restorative material on the shear bond strength of two-step and one-step self-etching adhesives to dentin, at three different time intervals of 24 h, 7 days, and 14 days. Materials and Methods: Forty extracted human posterior teeth were sectioned mesiodistally to obtain two halves and the resulting 80 halves were randomly assigned into four groups of 20 specimens each (Group-I, -II, -III, and -IV). Cavities of specified dimensions were prepared to expose dentin surface. In Group-I, temporarization was carried out with noneugenol cement (Orafil-G) for 24 h (control group). In Group-II, -III, and -IV, temporarization was carried out with eugenol cement (intermediate restorative material (IRM)) for 24 h, 7 days, and 14 days, respectively. Each group was further divided into two subgroups of 10 teeth each for two-step (Adper SE Plus) and one-step (Adper Easy One) self-etch adhesive systems, respectively. A plastic tube loaded with microhybrid composite resin (Filtek Z-350, 3M) was placed over the dentin surface and light cured. The specimens were subjected to shear stress in universal testing machine. Results: Group-II yielded low shear bond strength values compared with Group-III, -IV, and Group-I, which was statistically significant. Conclusions: The prior use of eugenol containing temporary restorative material reduced the bond strength of self-etch adhesive systems at 24-h period. No reduction in bond strength at 7 or 14 days exposure was observed with either two-step or one-step self-etch adhesive.

Nasreen, Farhat; Guptha, Anila Bandlapalli Sreenivasa; Srinivasan, Raghu; Chandrappa, Mahesh Martur; Bhandary, Shreetha; Junjanna, Pramod

2014-01-01

351

The influence of time of maternal exposure to 2,4,5,2 prime ,4 prime ,5 prime -hexachlorobiphenyl on its accumulation in their nursing offspring  

SciTech Connect

2,4,5,2',4',5'-Hexachlorobiphenyl (6-CB) is mobilized from rodent tissues during the lipid depletion associated with food restriction or lactation, the latter condition resulting in the substantial elimination of the maternal body burden of the chemical to nursing offspring. The present study was undertaken to determine whether the rate and/or magnitude of accumulation of 6-CB in nursing offspring differed with time following PCB administration to the maternal animal. Female ICR mice were administered two doses of 6-CB. Group I animals received (14C)-6-CB as weanlings (15-20 g) followed by unlabeled 6-CB 5 weeks later, after mating, on Day 1 of gestation. Group II received unlabeled 6-CB as weanlings and (14C)-6-CB on Day 1 of gestation. Thus, 14C identified the mobilization and elimination of either the first or the second dose of 6-CB in the treatment groups (I = (14C)-6-CB, 6-CB; II = 6-CB, (14C)-6-CB). Both groups of animals retained approximately 80% of the administered radiolabeled dose. The tissue distribution of (14C)-6-CB in group II as a percentage of the body burden was not different from that in group I as determined from maternal tissue concentrations on Day 14 of gestation. The percentage of the maternal body burden of (14C)-6-CB accumulated in suckling offspring of group II mothers was significantly greater than that in group I offspring on Day 1 (I, 2.2 +/- 0.5%; II, 3.5 +/- 0.4%), Day 3 (I, 14.8 +/- 1.9%; II, 24.6 +/- 2.7%), Day 5 (I, 16.8 +/- 1.4%; II, 24.8 +/- 0.8%), and Day 12 (I, 32.3 +/- 0.5%; II, 45.5 +/- 1.7%) postpartum. This differential elimination was reflected in the t1/2 of elimination of the radiolabeled dose from parametrial fat during lactation, which was significantly longer in group I (14 days) than group II maternal animals (9 days).

Gallenberg, L.A.; Ring, B.J.; Vodicnik, M.J. (Medical College of Wisconsin, Milwaukee (USA))

1990-06-01

352

Gray-scale lithography using mask-less exposure system  

Microsoft Academic Search

A fabrication process of precisely controlled three-dimensional patterns using a gray-scale lithography is presented. Multi-layered exposure patterns digitally generated by a mask-less exposure system are superposed on a photoresist-coated substrate layer by layer. Changing the exposure patterns and the exposure time of each exposure make the precise control of the profile of ultraviolet dose possible. The mask-less exposure system realizes

Kentaro Totsu; Kenta Fujishiro; Shuji Tanaka; Masayoshi Esashi

2005-01-01

353

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...

354

Phthalate Exposure and Children's Health  

PubMed Central

Purpose of Review Phthalates are multifunctional chemicals used in personal care products, medications, and plastics. We reviewed the epidemiological literature examining the relationship between early life phthalate exposure and pediatric health outcomes. Recent Findings Five studies from Asia, Europe, and the US suggest that childhood exposure to di-2-ethylhexyl phthalate (DEHP) and butylbenzyl phthalate (BBzP) may increase the risk of allergic diseases including asthma and eczema. Six studies from four different prospective cohorts report that gestational BBzP, DEHP, di-butyl phthalate (DBP), and di-ethyl phthalate (DEP) exposures are associated with alterations in infant/toddler physical development as well as parent-reported externalizing, internalizing, and autistic-like child behavior. However, there are inconsistencies related to the specific phthalates and behavioral domains. Two small studies report shorter anogenital distance among male infants with higher gestational phthalate exposure. Summary Several epidemiological studies suggest fetal and childhood exposure to some phthalates may perturb normal development, with several studies consistently reporting increased risk of allergic diseases with DEHP and BBzP exposure. While anticipatory guidance is not evidence-based at this time, providers can counsel concerned patients to reduce phthalate exposures in order to protect the developing fetus and child from potential adverse health outcomes.

Braun, Joseph M.; Sathyanarayana, Sheela; Hauser, Russ

2013-01-01

355

On the Accuracy of the Signal-to-Noise Estimates Obtained with the Exposure-Time Calculator of the Wide Field Planetary Camera 2 on Board the Hubble Space Telescope  

NASA Astrophysics Data System (ADS)

We have studied the accuracy and reliability of the exposure-time calculator (ETC) of the Wide Field Planetary Camera 2 (WFPC2) on board the Hubble Space Telescope (HST) with the objective of determining how well it represents actual observations and therefore how much confidence can be invested in it and in similar software tools. We have found, for example, that the ETC gives, in certain circumstances, very optimistic values for the signal-to-noise ratio (S/N) of point sources. These values overestimate by up to a factor of 2 the HST performance when simulations are needed to plan deep-imaging observations, thus bearing serious implications on observing-time allocation. For this particular case, we calculate the corrective factors to compute the appropriate S/N and detection limits, and we show how these corrections vary with field crowding and sky background. We also compare the ETC of the WFPC2 with a more general ETC tool, which takes into account the real effects of pixel size and charge diffusion. Our analysis indicates that similar problems may afflict other ETCs in general, showing the limits to which they are bound and the caution with which their results must be taken.

Li Causi, Gianluca; De Marchi, Guido; Paresce, Francesco

2002-07-01

356

The Short Time Exposure (STE) test for predicting eye irritation potential: intra-laboratory reproducibility and correspondence to globally harmonized system (GHS) and EU eye irritation classification for 109 chemicals.  

PubMed

Short Time Exposure (STE) test is an easy in vitro eye irritation test that assesses cytotoxicity in SIRC cells (rabbit corneal cell line) following a 5 min dose treatment. To assess intra-laboratory reproducibility, medium control, three vehicles (saline, saline containing 5% (w/w) dimethyl sulfoxide, and mineral oil) and three standard chemicals (sodium lauryl sulfate, calcium thioglycolate, and Tween 80) were evaluated. Assessments were repeated 30 times for vehicles and 18 times for standard chemicals; resulting in almost the same cell viability and a low coefficient of variation value. In addition, the STE eye irritation rankings of three standard chemicals, as calculated on the cell viabilities in 5% and 0.05% solutions were in agreement in all tests. Based on these results, high intra-laboratory reproducibility was confirmed. In addition, the irritation category (irritant and non-irritant) was evaluated for 109 chemicals with STE test, globally harmonized system (GHS) classification, and European Union (EU) classification. The results of the evaluation found the STE classification to have an accuracy with GHS classification of 87% and with EU classification of 83%, which confirmed the excellent correspondence. The correspondence of STE rankings (1, 2, and 3) based on the prediction model by STE test with the eye irritation rankings by GHS (non-irritant, categories 2 and 1) and EU (non-irritant, R36, and R41) was 76% and 71%, respectively. Based on the above results, STE test was considered to be a promising alternative method for assessing eye irritation that has high intra-laboratory reproducibility as well as an excellent predictability of eye irritation. PMID:21513790

Takahashi, Yutaka; Hayashi, Kazuhiko; Abo, Takayuki; Koike, Mirei; Sakaguchi, Hitoshi; Nishiyama, Naohiro

2011-10-01

357

Modeling Cadmium Exposures in Low- and High-Exposure Areas in Thailand  

PubMed Central

Background: Previous U.S. population modeling studies have reported that urinary cadmium (Cd) excretion patterns differ with age, sex, and dietary exposure; associations between Cd exposures and health outcomes also have differed by age and sex. Therefore, it is important to test models used to estimate Cd exposures across an expanded Cd-exposure range. Objectives: We estimated relative Cd exposures from both diet and smoking in low- and high-exposure scenarios to provide data for improving risk assessment calculations. Methods: We used a Cd toxicokinetic–based model to estimate Cd exposures based on urinary Cd levels measured for 399 persons in a low-exposure area (Bangkok) and 6,747 persons in a high-exposure area (Mae Sot) in Thailand. Results: In Bangkok, we estimated dietary Cd exposures of 50–56 µg/day for males and 21–27 µg/day for females 20–59 years of age who never smoked. In Mae Sot, we estimated dietary Cd exposures of 188–224 µg/day for males and 99–113 µg/day for females 20–59 years of age who never smoked. In Bangkok, we estimated Cd exposures from smoking to be 5.5–20.4 µg/day for male smokers 20–59 years of age. In Mae Sot, we estimated Cd exposures from smoking to be 9.8–26 µg/day for male heavy smokers and 26 µg/day for female heavy smokers. Conclusion: This study provides estimates of Cd exposures from diet and smoking in low- and high-exposure scenarios. Our findings suggest a relatively small safety margin between the established tolerable Cd reference exposure of 62 µg/day and exposure levels previously associated with evidence of kidney and bone effects in Mae Sot residents, where dietary Cd exposures among women were only 1.6–2.1 times the reference value.

Swaddiwudhipong, Witaya; Ruangyuttikarn, Werawan; Nishijo, Muneko; Ruiz, Patricia

2013-01-01

358

Reference Gene Selection for Quantitative Real-Time RT-PCR Normalization in the Half-Smooth Tongue Sole (Cynoglossus semilaevis) at Different Developmental Stages, in Various Tissue Types and on Exposure to Chemicals  

PubMed Central

Quantitative real time RT-PCR has been described as the most sensitive method for the detection of low abundance mRNA. To date, no reference genes have been screened in the half-smooth tongue sole (Cynoglossus semilaevis). The aim of this study was to select the most stable genes for quantitative real-time RT-PCR. Eight housekeeping genes (18S, TUBA, B2M, ACTB, EF1A, GAPDH, RPL17 and UBCE) were tested at different developmental stages, in different tissues, and following exposure to the drug SB-431542. Using geNorm, BestKeeper and NormFinder software, GAPDH/B2M, GAPDH/18S and UBCE/GAPDH were identified as the most suitable genes from samples taken of different developmental stages while 18S/RPL17 were consistently ranked as the best reference genes for different tissue types. Furthermore, TUBA/B2M, TUBA/UBCE and B2M/TUBA were found to be the most suitable genes in samples treated with the drug, SB-431542 by geNorm, BestKeeper and NormFinder respectively. Across both different developmental stages and tissue types, the combination of 18S and GAPDH was the most stable reference gene analyzed by Ref-Finder. To test and verify the screened reference genes, the expression profiles of LEFTY-normalized to the combination of GAPDH/18S and ACTB were presented. These results will be useful for future gene-expression studies in the half-smooth tongue sole.

Liu, Conghui; Xin, Nian; Zhai, Yi; Jiang, Liming; Zhai, Jieming; Zhang, Quanqi; Qi, Jie

2014-01-01

359

Reference gene selection for quantitative real-time RT-PCR normalization in the half-smooth tongue sole (Cynoglossus semilaevis) at different developmental stages, in various tissue types and on exposure to chemicals.  

PubMed

Quantitative real time RT-PCR has been described as the most sensitive method for the detection of low abundance mRNA. To date, no reference genes have been screened in the half-smooth tongue sole (Cynoglossus semilaevis). The aim of this study was to select the most stable genes for quantitative real-time RT-PCR. Eight housekeeping genes (18S, TUBA, B2M, ACTB, EF1A, GAPDH, RPL17 and UBCE) were tested at different developmental stages, in different tissues, and following exposure to the drug SB-431542. Using geNorm, BestKeeper and NormFinder software, GAPDH/B2M, GAPDH/18S and UBCE/GAPDH were identified as the most suitable genes from samples taken of different developmental stages while 18S/RPL17 were consistently ranked as the best reference genes for different tissue types. Furthermore, TUBA/B2M, TUBA/UBCE and B2M/TUBA were found to be the most suitable genes in samples treated with the drug, SB-431542 by geNorm, BestKeeper and NormFinder respectively. Across both different developmental stages and tissue types, the combination of 18S and GAPDH was the most stable reference gene analyzed by Ref-Finder. To test and verify the screened reference genes, the expression profiles of LEFTY-normalized to the combination of GAPDH/18S and ACTB were presented. These results will be useful for future gene-expression studies in the half-smooth tongue sole. PMID:24667563

Liu, Conghui; Xin, Nian; Zhai, Yi; Jiang, Liming; Zhai, Jieming; Zhang, Quanqi; Qi, Jie

2014-01-01

360

Ultraviolet exposure enhanced silicon direct bonding  

Microsoft Academic Search

Ultraviolet (UV) exposure, as an additional technique following the traditional wet chemical activation processes, is applied\\u000a to enhance hydrophilic silicon direct bonding. The effects of UV exposure on silicon wafers’ nano-topography and bonding strength\\u000a are studied. It is found that the surface roughness of silicon wafers initially decreases and then increases with UV exposure\\u000a time, and the bonding strength increases

Guanglan Liao; Xuekun Zhang; Xiaohui Lin; Canghai Ma; Lei Nie; Tielin Shi

2010-01-01

361

Lead exposure at uncovered outdoor firing ranges.  

PubMed

Excessive lead exposure in shooting instructors at indoor firing ranges and covered outdoor firing ranges has been documented. The City of Los Angeles assessed exposure of its full-time shooting instructors at uncovered outdoor ranges via air monitoring and blood lead-level measurements. Results of these tests revealed that significant lead exposure and absorption can occur at outdoor firing ranges. The use of copper-jacketed ammunition may decrease air lead levels and decrease lead absorption by range instructors. PMID:1865252

Goldberg, R L; Hicks, A M; O'Leary, L M; London, S

1991-06-01

362

Lead exposure at uncovered outdoor firing ranges  

SciTech Connect

Excessive lead exposure in shooting instructors at indoor firing ranges and covered outdoor firing ranges has been documented. The City of Los Angeles assessed exposure of its full-time shooting instructors at uncovered outdoor ranges via air monitoring and blood lead-level measurements. Results of these tests revealed that significant lead exposure and absorption can occur at outdoor firing ranges. The use of copper-jacketed ammunition may decrease air lead levels and decrease lead absorption by range instructors.

Goldberg, R.L.; Hicks, A.M.; O'Leary, L.M.; London, S. (University of Southern California School of Medicine, Los Angeles (USA))

1991-06-01

363

DEMONSTRATION OF HUMAN EXPOSURE TOOLS  

EPA Science Inventory

The Human Exposure and Atmospheric Sciences Division (HEASD) of the National Exposure Research Laboratory (NERL) conducts research on exposure measurements, human activity patterns, exposure and dose models, and cumulative exposures critical for the Agency to make scientificall...

364

Preschool Teachers' Exposure to Classroom Noise  

ERIC Educational Resources Information Center

This research examined exposure to classroom noise of 25 full-time teaching staff in 14 preschool settings located across Western Sydney. The results indicated that one teacher exceeded the maximum permissible level of daily noise exposure for employees under the health and safety legislation. Three staff approached this level and 92% of teachers…

Grebennikov, Leonid

2006-01-01

365

Integrated Exposure Assessment Monitoring.  

ERIC Educational Resources Information Center

Integrated Exposure Assessment Monitoring is the coordination of environmental (air, water, land, and crops) monitoring networks to collect systematically pollutant exposure data for a specific receptor, usually man. (Author/BB)

Behar, Joseph V.; And Others

1979-01-01

366

Hypotension during Bromotrifluoromethane Exposure.  

National Technical Information Service (NTIS)

Cardiac output and mean arterial blood pressure measurements were performed on anesthetized dogs during exposure to bromotrifluoromethane. Left ventricular end diastolic pressure was recorded from anesthetized open-chested dogs and monkeys during exposure...

E. W. Van Stee K. C. Back

1971-01-01

367

CHAPTER ONE: EXPOSURE MEASUREMENTS.  

EPA Science Inventory

Determining human exposure to suspended particualte concentrations requires measurements that quantify different particle properties in microenvironments where people live, work, and play. Particle mass, size, and chemical composition are important exposure variables, and these ...

368

SUPERFUND EXPOSURE ASSESSMENT MANUAL  

EPA Science Inventory

Manual provides a framework for the assessment of exposure to contaminants at or migrating from uncontrolled hazardous waste sites, covering the application of both monitoring and modeling procedures to the exposure assessment process. This process considers all contaminant relea...

369

IDENTIFYING CRITICAL WINDOWS OF EXPOSURE FOR CHILDREN'S HEALTH  

EPA Science Inventory

Several authors have considered the importance of exposure timing and how this affects the outcomes observed, but no one has systematically compiled preconceptional, prentatal, and postnatal developmental exposures and subsequent outcomes. Efforts were undertaken to examine the ...

370

Understanding Greek Primary School Children's Comprehension of Sun Exposure.  

ERIC Educational Resources Information Center

Assesses Greek primary school children's understanding of sun exposure during summer vacation. Results indicate that children know the damaging effects of long time exposure and the precautions that should be taken during summer bathing. (Author/SOE)

Piperakis, Stylianos M.; Papadimitriou, Vasiliki; Piperakis, Michael M.; Zisis, Panagiotis

2003-01-01

371

Long Duration Exposure Facility  

NASA Technical Reports Server (NTRS)

This is an onboard photo of the deployment of the Long Duration Exposure Facility (LDEF) from the cargo bay of the Space Shuttle Orbiter Challenger STS-41C mission, April 7, 1984. After a five year stay in space, the LDEF was retrieved during the STS-32 mission by the Space Shuttle Orbiter Columbia in January 1990 and was returned to Earth for close examination and analysis. The LDEF was designed by the Marshall Space Flight Center (MSFC) to test the performance of spacecraft materials, components, and systems that have been exposed to the environment of micrometeoroids, space debris, radiation particles, atomic oxygen, and solar radiation for an extended period of time. Proving invaluable to the development of both future spacecraft and the International Space Station (ISS), the LDEF carried 57 science and technology experiments, the work of more than 200 investigators, 33 private companies, 21 universities, 7 NASA centers, 9 Department of Defense laboratories, and 8 forein countries.

1984-01-01

372

The patient with asbestos exposure.  

PubMed

Attention to the hazards of asbestos has aroused concern among many healthy persons who have been exposed at some time to one of the world's most versatile materials. Present standards for exposure to asbestos, however, may not fully protect workers from asbestos-induced pulmonary malignancy. To evaluate the patient who has had some asbestos exposure, the physician should focus on the pulmonary system, take a thorough occupational history, conduct a physical examination and pulmonary function studies, and obtain chest films. In managing the patient with asbestosis, removal from further occupational exposure is advisable. For workers with only pleural changes, it is unclear whether removal from the work place is of any value. PMID:3941302

McCunney, R J

1986-01-01

373

GUIDELINES FOR EXPOSURE ASSESSMENT  

EPA Science Inventory

The Guidelines for Exposure Assessment describe the general concepts of exposure assessment including definitions and associated units, and by providing guidance on the planning and conducting of an exposure assessment. Guidance is also provided on presenting the results of the e...

374

IR Detector Timing and Persistence  

NASA Astrophysics Data System (ADS)

The IR detector on WFC3 exhibits after images, known as persistence, following exposure to light that exceeds half saturation of individual pixels of the detector. The IR channel of WFC3 has no shutter and therefore light from bright objects reaches the detector between science exposures. For estimating persistence, the time that is important is the time between pixel resets. In intervals between science exposures, all pixels are discharged or reset every 2.91 s. For full-frame exposures, the time between resets is the science exposure time (EXPTIME) plus 5.82 s. Since fullframe exposures are usually much longer than 5.82 s, the difference between the time between resets and the science exposure time is usually not a significant problem for estimating persistence in full-frame exposures. However, the science exposure time for certain sub-array sequences can be considerably shorter than the time between resets, and in these cases, the persistence can be much greater than one expects if the time between resets is not correctly calculated. Here we discusses details of detector timing in order to allow a more accurate estimate of the effective persistence exposure time during an observation.

Long, Knox S.; Wheeler, Thomas; Bushouse, Howard

2011-04-01

375

Biological Response to SPE Exposures  

NASA Technical Reports Server (NTRS)

It has long been recognized that a single solar particle event (SPE) can produce, over a short period of time, exposures on the order of LD50 for humans under normal physiological conditions. It is further recognized that recovery from injury over the period of exposure would greatly increase the chances of survival (dose rate effects) although such effects were left unquantified. In the present report we use the bioresponse model derived from a broad range of animal and human exposure data for evaluation of troop readiness in tactical nuclear warfare to evaluate the biological risk posed by the solar event of 4 August 1972. The astronaut blood forming organ (BFO) exposure in deep space would have been 2.2 Sv (1.6 Gy) in a space suit, 1.8 Sv (1.3 Gy) in an aluminum pressure vessel, and 0.7 Sv (0.5 Gy) in an equipment room compared to an X-ray mortality threshold of 1.5 Gy (assuming high dose rate). We find BFO dose rate effectiveness factors for this SPE on the order of 3 to 4, greatly reducing the mortality risks for this event. There is an approximate 3 percent chance that an even larger event may occur for which exposures could be 2-4 times higher. Assured survival of the astronaut requires added shelter shielding and a warning system for this event. The required mass of the shelter shield can be greatly reduced by using hydrogenous materials such as polymers, water, food, and other biological materials in its construction. Limitations of the current bioresponse model arise from the exposures taking place in the microgravity environment wherein the immune system is already challenged and the effective mortality threshold may be reduced by a factor of two. Such microgravity effects could greatly affect astronaut risks.

Wilson, J. W.; Cucinotta, F. A.; Kim, M.; Shinn, J. L.; Jones, T. D.; Chang, C. K.

2004-01-01

376

Thermal Spore Exposure Vessels  

NASA Technical Reports Server (NTRS)

Thermal spore exposure vessels (TSEVs) are laboratory containers designed for use in measuring rates of death or survival of microbial spores at elevated temperatures. A major consideration in the design of a TSEV is minimizing thermal mass in order to minimize heating and cooling times. This is necessary in order to minimize the number of microbes killed before and after exposure at the test temperature, so that the results of the test accurately reflect the effect of the test temperature. A typical prototype TSEV (see figure) includes a flat-bottomed stainless-steel cylinder 4 in. (10.16 cm) long, 0.5 in. (1.27 cm) in diameter, having a wall thickness of 0.010 plus or minus 0.002 in. (0.254 plus or minus 0.051 mm). Microbial spores are deposited in the bottom of the cylinder, then the top of the cylinder is closed with a sterile rubber stopper. Hypodermic needles are used to puncture the rubber stopper to evacuate the inside of the cylinder or to purge the inside of the cylinder with a gas. In a typical application, the inside of the cylinder is purged with dry nitrogen prior to a test. During a test, the lower portion of the cylinder is immersed in a silicone-oil bath that has been preheated to and maintained at the test temperature. Test temperatures up to 220 C have been used. Because the spores are in direct contact with the thin cylinder wall, they quickly become heated to the test temperature.

Beaudet, Robert A.; Kempf, Michael; Kirschner, Larry

2006-01-01

377

Loud noise exposure and acoustic neuroma.  

PubMed

The results from studies of loud noise exposure and acoustic neuroma are conflicting. A population-based case-control study of 451 acoustic neuroma patients and 710 age-, sex-, and region-matched controls was conducted in Sweden between 2002 and 2007. Occupational exposure was based on historical measurements of occupational noise (321 job titles summarized by a job exposure matrix) and compared with self-reported occupational noise exposure. We also evaluated self-reported noise exposure during leisure activity. Conditional logistic regression was used to estimate odds ratios. There was no statistically significant association between acoustic neuroma and persistent occupational noise exposure, either with or without hearing protection. Exposure to loud noise from leisure activity without hearing protection was more common among acoustic neuroma cases (odds ratio = 1.47, 95% confidence interval: 1.06, 2.03). Statistically significant odds ratios were found for specific leisure activities including attending concerts/clubs/sporting events (odds ratio = 1.82, 95% confidence interval: 1.09, 3.04) and participating in workouts accompanied by loud music (odds ratio = 2.84, 95% confidence interval: 1.37, 5.89). Our findings do not support an association between occupational exposure to loud noise and acoustic neuroma. Although we report statistically significant associations between leisure-time exposures to loud noise without hearing protection and acoustic neuroma, especially among women, we cannot rule out recall bias as an alternative explanation. PMID:24786799

Fisher, James L; Pettersson, David; Palmisano, Sadie; Schwartzbaum, Judith A; Edwards, Colin G; Mathiesen, Tiit; Prochazka, Michaela; Bergenheim, Tommy; Florentzson, Rut; Harder, Henrik; Nyberg, Gunnar; Siesjö, Peter; Feychting, Maria

2014-07-01

378

Some limitations of aggregate exposure metrics.  

PubMed

Aggregate exposure metrics based on sums or weighted averages of component exposures are widely used in risk assessments of complex mixtures, such as asbestos-associated dusts and fibers. Allowed exposure levels based on total particle or fiber counts and estimated ambient concentrations of such mixtures may be used to make costly risk-management decisions intended to protect human health and to remediate hazardous environments. We show that, in general, aggregate exposure information alone may be inherently unable to guide rational risk-management decisions when the components of the mixture differ significantly in potency and when the percentage compositions of the mixture exposures differ significantly across locations. Under these conditions, which are not uncommon in practice, aggregate exposure metrics may be "worse than useless," in that risk-management decisions based on them are less effective than decisions that ignore the aggregate exposure information and select risk-management actions at random. The potential practical significance of these results is illustrated by a case study of 27 exposure scenarios in El Dorado Hills, California, where applying an aggregate unit risk factor (from EPA's IRIS database) to aggregate exposure metrics produces average risk estimates about 25 times greater - and of uncertain predictive validity - compared to risk estimates based on specific components of the mixture that have been hypothesized to pose risks of human lung cancer and mesothelioma. PMID:17511710

Cox, Louis Anthony; Popken, Douglas A

2007-04-01

379

Skin Exposure and Asthma  

PubMed Central

Numerous occupational and environmental exposures that increase asthma risk have been identified. Research and prevention have focused primarily on the respiratory tract. However, recent studies suggest that the skin may also be an important route of exposure and site of sensitization that contributes to asthma development. Factors that impair skin barrier function, such as filaggrin gene mutations or skin trauma, may facilitate allergen entry and promote Th2-like sensitization and subsequent asthma. Animal studies demonstrate that skin exposure to chemical and protein allergens is highly effective at inducing sensitization, with subsequent inhalation challenge eliciting asthmatic responses. A similar role for human skin exposure to certain sensitizing agents, such as isocyanates, is likely. Skin exposure methodologies are being developed to incorporate skin exposure assessment into epidemiology studies investigating asthma risk factors.

Redlich, Carrie A.

2010-01-01

380

Exposure and time dependent DNA strand breakage in hepatopancreas of green-lipped mussels (Perna viridis) exposed to Aroclor 1254, and mixtures of B[a]P and Aroclor 1254.  

PubMed

Green-lipped mussels (Perna viridis) were exposed to Aroclor 1254 (0.5, 5 and 50 microgl(-1)) and a mixture of benzo[a]pyrene (B[a]P) and Aroclor 1254 (0.3+0.5 and 3+5 microgl(-1)) for 12 days. On day 0, 1, 3, 6 and 12, the levels of DNA strand breaks in the mussel hepatopancreas were monitored using an alkaline unwinding assay. The results were compared to the findings of a previous study in which the levels of DNA strand breakage in the same species were measured following exposure to various concentrations of B[a]P (0.3, 3 and 30 microgl(-1)). The results indicated that Aroclor 1254 at a concentration exposure, followed by an apparent rapid recovery. In contrast, exposure to 30 microgl(-1) B[a]P caused no increase in DNA strand breaks over the exposure period. This was postulated to be due to an early elicitation of the DNA repair system by the relatively high exposure level of B[a]P. This hypothesis was tested in the present study, and the results suggest that exposure to the high B[a]P concentration might have elicited the defense mechanism within the mussels, resulting in no observed increase in DNA strand breaks. An increase in strand breaks was, however, evident when the mussels were exposed to lower B[a]P levels. The levels of DNA strand breaks were correlated with the body burden of B[a]P and Aroclor 1254 but no significant relationship was observed, possibly owing to the rapid metabolism of the toxicant and/or an effective DNA repair mechanism. As a result, DNA strand breakage in the hepatopancreas of green-lipped mussels may not be a suitable biomarker of exposure to the above toxicants in the marine environment. Our findings also suggest that it would be instructive to investigate (1) the role of DNA repair enzymes in the exposed mussels; and (2) the correlation between the activity of these enzymes and the body burden of specific toxicants. PMID:14550341

Siu, W H L; Hung, C L H; Wong, H L; Richardson, B J; Lam, P K S

2003-10-01

381

BATSE sky exposure  

SciTech Connect

Angular sky exposure is presented for a number of published BATSE gamma-ray burst catalogs. A new algorithm was required due to telemetry gaps resulting from onboard tape recorder failures; the new algorithm improves the 1B Catalog exposure calculation. The most influential effects limiting BATSE's exposure are (1) deadtime due to triggering, (2) sky blockage by the Earth, and (3) trigger disabling when the spacecraft is in the SAA and over other specific Earth locations. Exposure has improved during the Compton Gamma-Ray Observatory (CGRO) mission as a result of decreased Solar flares and magnetospheric particle events.

Hakkila, Jon [Mankato State University, Mankato Minnesota 56002-8400 (United States); Meegan, Charles A. [NASA/Marshall Space Flight Center, Huntsville, Alabama 35812 (United States); Pendleton, Geoffrey N.; Briggs, Michael S. [University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Henze, William [Teledyne Brown at NASA/MSFC, Huntsville, Alabama 35812 (United States); McCollough, Michael [USRA at NASA/MSFC, Huntsville, Alabama 35812 (United States); Kommers, Jefferson M. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

1998-05-16

382

Coded exposure photography: motion deblurring using fluttered shutter  

Microsoft Academic Search

In a conventional single-exposure photograph, moving objects or moving cameras cause motion blur. The exposure time defines a temporal box filter that smears the moving object across the image by convolution. This box filter destroys important high-frequency spatial details so that deblurring via deconvolution becomes an ill- posed problem. Rather than leaving the shutter open for the entire exposure du-

Ramesh Raskar; Amit K. Agrawal; Jack Tumblin

2006-01-01

383

Occupational Exposure to Metalworking Fluid Mist and Sump Fluid Contaminants  

Microsoft Academic Search

This paper summarizes the analytical and occupational hygiene findings from a recent survey of occupational exposure to metalworking fluids (MWFs) in the engineering industry. The aim of the survey was to link MWF mist exposure measurements with particular engineering processes and controls, and utilize the data obtained to develop exposure standards. At the same time the opportunity was taken to

A. T. SIMPSON; M. STEAR; J. A. GROVES; M. PINEY; S. D. BRADLEY; S. STAGG; B. CROOK

2003-01-01

384

Latency models for analyses of protracted exposures.  

PubMed

The effect of an increment of exposure on disease risk may vary with time-since-exposure. If the pattern of temporal variation is simple (eg, a peak and then a decline in excess risk of disease) then this may be modeled efficiently via a parametric latency function. Estimation of the parameters for such a model can be difficult because the parameters are not a function of a simple summary of the exposure history. Typically, such parameters are estimated via an iterative search that requires calculating a different time-weighted exposure for each combination of the latency function parameters. This article describes a simple approach to fitting logistic regression models that include a parametric latency function. This approach is illustrated using data from a study of the association between radon exposure and lung cancer mortality among underground uranium miners. This approach should facilitate fitting models to assess variation with time since exposure in the effect of a protracted environmental or occupational exposure. PMID:19262389

Richardson, David B

2009-05-01

385

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

PubMed Central

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

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

1993-01-01

386

Exposures from headset interference tones  

NASA Astrophysics Data System (ADS)

This study evaluated the acoustic characteristics of interference tones as experienced by FAA Air Traffic Control Specialists (ATCS's) and pilots who wear headsets with insert type ear pieces. The sound pressure levels (SPL's) of generated tones were measured through the headset at five randomly selected ATCS positions in each of seven Air Route Traffic Control Centers (ARTCC's). The SPL's were compared within and between four frequencies (.5, 1, 2, and 3 KHz) over ten discrete signal power levels. The comparisons demonstrated that SPL's of tones could not be predicted for ARTCC's or for positions within an ARTCC, and that the durations of exposure were brief, i.e., limited to the time needed to remove the headset earpiece from the ear canal. Potential amounts of temporary threshold shifts (TTS's) also were evaluated in a laboratory by checking hearing levels following exposures to tones played with ATCS/pilot communication through the same headset. Audiometric checks of 20 volunteer subjects indicated TTS could be detected following 1 KHz/114 dB/60 and 145 seconds, 2 KHz/108 dB/60 and 145 seconds, and 3 KHz/99 dB/145 seconds exposures, when hearing checks were made within the first 15 minutes. Such extended durations are highly unlikely for pilots and ATCS's and no TTS was detectable following exposures to shorter durations or to other frequencies with equivalent durations.

May, Noal D.

1992-01-01

387

Modeling community asbestos exposure near a vermiculite processing facility: Impact of human activities on cumulative exposure.  

PubMed

Contaminated vermiculite ore from Libby, Montana was processed in northeast Minneapolis from 1936 to 1989 in a densely populated urban residential neighborhood, resulting in non-occupational exposure scenarios from plant stack and fugitive emissions as well as from activity-based scenarios associated with use of the waste rock in the surrounding community. The objective of this analysis was to estimate potential cumulative asbestos exposure for all non-occupationally exposed members of this community. Questionnaire data from a neighborhood-exposure assessment ascertained frequency of potential contact with vermiculite processing waste. Monte Carlo simulation was used to develop exposure estimates based on activity-based concentration estimates and contact durations for four scenarios: S1, moved asbestos-contaminated waste; S2, used waste at home, on lawn or garden; S3, installed/removed vermiculite insulation; S4, played in or around waste piles at the plant. The simulation outputs were combined with air-dispersion model results to provide total cumulative asbestos exposure estimates for the cohort. Fiber emissions from the plant were the largest source of exposure for the majority of the cohort, with geometric mean cumulative exposures of 0.02 fibers/cc × month. The addition of S1, S2 and S3 did not significantly increase total cumulative exposure above background exposure estimates obtained from dispersion modeling. Activity-based exposures were a substantial contributor to the upper end of the exposure distribution: 90th percentile S4 exposure estimates are ?10 times higher than exposures from plant emissions. Pile playing is the strongest source of asbestos exposure in this cohort, with other activity scenarios contributing less than from plant emissions. PMID:21343955

Adgate, John L; Cho, Sook Ja; Alexander, Bruce H; Ramachandran, Gurmurthy; Raleigh, Katherine K; Johnson, Jean; Messing, Rita B; Williams, A L; Kelly, James; Pratt, Gregory C

2011-01-01

388

Thermal Evaluation of a Polyvinylchloride Exposure Suit (Empress) and Comparison with Present Submarine Deck Exposure Suit.  

National Technical Information Service (NTIS)

The study determined the general performance and survival times afforded by the 'Empress' polyvinylchloride exposure suit (PVES) and the present submarine deck exposure suit in 44F water, 32F air, and 20 MPH wind speed. Tests were also conducted utilizing...

D. A. Hall J. J. Nobel

1968-01-01

389

Sufficient vitamin D from casual sun exposure?  

PubMed

Next to the adverse effects of solar UV exposure, the beneficial effects mediated by vitamin D(3) have come into the limelight. The question then is "how much sun exposure do we actually need?" Estimates have been made, but the data are not quite adequate. The groups of Drs. Rhodes and Webb bridged the gap between experiments and everyday life by a study in which 109 volunteers were exposed in mid-winter to simulated solar UV radiation in summertime clothing at dosages of 1.3 SED three times a week. Thus, 90% reached sufficiently high vitamin D statuses (>50 nmol L(-1)). In this issue, these researchers transpose these experimental exposures in a cabinet to summertime noon exposures of people walking around for about half an hour in open terrain on a clear day in Manchester, UK. This result is an improvement over earlier estimates and shows that casual mid-day summer sun exposure should indeed suffice. PMID:21388384

de Gruijl, Frank R

2011-01-01

390

Avian inhalation exposure chamber  

DOEpatents

An exposure system for delivering gaseous material ranging in particle size from 0.4 micrometers to 20.0 micrometers uniformly to the heads of experimental animals, primarily birds. The system includes a vertical outer cylinder and a central chimney with animal holding bottles connected to exposure ports on the vertical outer cylinder.

Briant, James K. (P.O. Box 999, Richland, WA 99352); Driver, Crystal J. (P.O. Box 999, Richland, WA 99352)

1992-01-01

391

A Revealing Exposure.  

ERIC Educational Resources Information Center

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…

Evans, Kenneth H.

1992-01-01

392

Radiation Exposure Compensation Program  

NSDL National Science Digital Library

This is the Justice Department's Radiation Exposure Compensation Pro