Note: This page contains sample records for the topic radiodiagnostic exposure time from
While these samples are representative of the content of,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of
to obtain the most current and comprehensive results.
Last update: November 12, 2013.

Major Radiodiagnostic Imaging in Pregnancy and the Risk of Childhood Malignancy: A Population-Based Cohort Study in Ontario  

PubMed Central

Background The association between fetal exposure to major radiodiagnostic testing in pregnancy—computed tomography (CT) and radionuclide imaging—and the risk of childhood cancer is not established. Methods and Findings We completed a population-based study of 1.8 million maternal-child pairs in the province of Ontario, from 1991 to 2008. We used Ontario's universal health care–linked administrative databases to identify all term obstetrical deliveries and newborn records, inpatient and outpatient major radiodiagnostic services, as well as all children with a malignancy after birth. There were 5,590 mothers exposed to major radiodiagnostic testing in pregnancy (3.0 per 1,000) and 1,829,927 mothers not exposed. The rate of radiodiagnostic testing increased from 1.1 to 6.3 per 1,000 pregnancies over the study period; about 73% of tests were CT scans. After a median duration of follow-up of 8.9 years, four childhood cancers arose in the exposed group (1.13 per 10,000 person-years) and 2,539 cancers in the unexposed group (1.56 per 10,000 person-years), a crude hazard ratio of 0.69 (95% confidence interval 0.26–1.82). After adjusting for maternal age, income quintile, urban status, and maternal cancer, as well as infant sex, chromosomal or congenital anomalies, and major radiodiagnostic test exposure after birth, the risk was essentially unchanged (hazard ratio 0.68, 95% confidence interval 0.25–1.80). Conclusions Although major radiodiagnostic testing is now performed in about 1 in 160 pregnancies in Ontario, the absolute annual risk of childhood malignancy following exposure in utero remains about 1 in 10,000. Since the upper confidence limit of the relative risk of malignancy may be as high as 1.8 times that of an unexposed pregnancy, we cannot exclude the possibility that fetal exposure to CT or radionuclide imaging is carcinogenic. Please see later in the article for the Editors' Summary

Ray, Joel G.; Schull, Michael J.; Urquia, Marcelo L.; You, John J.; Guttmann, Astrid; Vermeulen, Marian J.



Radiodiagnostic Imaging in Pregnancy and the Risk of Childhood Malignancy: Raising the Bar  

Microsoft Academic Search

Eduardo Franco and Guy-Anne Turgeon discuss new findings from Joel Ray and colleagues on the cancer risk following prenatal exposure to radiodiagnostic imaging, and where new research needs to be focused.

Eduardo L. Franco; Guy-Anne Turgeon



Report of an image quality and dose audit according to Directive 97\\/43\\/Euratom at Spanish private radiodiagnostics facilities  

Microsoft Academic Search

An audit of Spanish private medicine radiodiagnostics facilities has been carried out, based partly on Spanish legislation relating to European Directives on health protection against ionizing radiation risks in medical exposure. The study included an appraisal of infrastructure and equipment, and aspects of quality assurance and radiation protection, by means of data col- lected through surveys. Of the 51 centres



AETC: Advanced Exposure Time Calculator  

NASA Astrophysics Data System (ADS)

We describe a tool (AETC: Advanced Exposure Time Calculator) to simulate images of astrophysical objects obtained with any combination of telescope, instrument and given pass band using a suitable set of parameters that define the configuration of the equipment used for the observations. The tool provides count rates and its distribution over the focal plane, through the proper definition of the PSF, of virtually any telescope equipped with an imager provided that its configuration is assessed. Effects of non-uniform PSF over the Field of View can also be modeled. Moreover, detailed simulation of the observed fields can be simulated including stars, galaxies and more complex objects providing template of the targets. The tool is available at:

Falomo, Renato; Fantinel, Daniela; Uslenghi, Michela



Predicting Survival Time for Cold Exposure.  

National Technical Information Service (NTIS)

The prediction of survival time (ST) for cold exposure is speculative as reliable controlled data of deep hypothermia are unavailable. At best, guidance can be obtained from case histories of accidental exposure. This study describes the development of a ...

P. Tikuisis



ETC++: Advanced Exposure-Time Calculations  

NASA Astrophysics Data System (ADS)

ETC++ is a exposure-time calculator that considers the effect of cosmic rays, undersampling, dithering, and imperfect pixel response functions. Errors on astrometry and galaxy shape measurements can be predicted as well as photometric errors.

Bernstein, Gary



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



Comparison of the kinetics of methylene-diphosphonate (MDP) and dicarboxypropan-diphosphonic acid (DPD), two radio-diagnostics for bone scintigraphy  

Microsoft Academic Search

Two 99mTc-labelled radio-diagnostics for bone scintigraphy, dicarboxypropan-diphosphonic acid (DPD) and methylene-diphosphonate (MDP) were compared. The test parameters were the time-activity curves of serum and of deproteinised serum, time-activity curves in regions of interest above the femur, the sacrum and the soft tissue medial of the femur, and the urinary excretion. The ratio of bone lesion to normal bone was compared

Hans-Joachim Schroth; Franz Hausinger; Herbert Garth; Erich Oberhausen



Predicting survival time for cold exposure  

NASA Astrophysics Data System (ADS)

The prediction of survival time (ST) for cold exposure is speculative as reliable controlled data of deep hypothermia are unavailable. At best, guidance can be obtained from case histories of accidental exposure. This study describes the development of a mathematical model for the prediction of ST under sedentary conditions in the cold. The model is based on steady-state heat conduction in a single cylinder comprised of a core and two concentric annular shells representing the fat plus skin and the clothing plus still boundary layer, respectively. The ambient condition can be either air or water; the distinction is made by assigning different values of insulation to the still boundary layer. Metabolic heat production ( M) is comprised of resting and shivering components with the latter predicted by temperature signals from the core and skin. Where the cold exposure is too severe for M to balance heat loss, ST is largely determined by the rate of heat loss from the body. Where a balance occurs, ST is governed by the endurance time for shivering. End of survival is marked by the deep core temperature reaching a value of 30° C. The model was calibrated against survival data of cold water (0 to 20° C) immersion and then applied to cold air exposure. A sampling of ST predictions for the nude exposure of an average healthy male in relatively calm air (1 km/h wind speed) are the following: 1.8, 2.5, 4.1, 9.0, and >24 h for -30, -20, -10, 0, and 10° C, respectively. With two layers of loose clothing (average thickness of 1 mm each) in a 5 km/h wind, STs are 4.0, 5.6, 8.6, 15.4, and >24 h for -50, -40, -30, -20, and -10° C. The predicted STs must be weighted against the extrapolative nature of the model. At present, it would be prudent to use the predictions in a relative sense, that is, to compare or rank-order predicted STs for various combinations of ambient conditions and clothing protection.

Tikuisis, Peter




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...


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.



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



Time–activity relationships to VOC personal exposure factors  

Microsoft Academic Search

Social and demographic factors have been found to play a significant role in differences between time–activity patterns of population subgroups. Since time–activity patterns largely influence personal exposure to compounds as individuals move across microenvironments, exposure subgroups within the population may be defined by factors that influence daily activity patterns. Socio-demographic and environmental factors that define time–activity subgroups also define quantifiable

Rufus D. Edwards; Christian Schweizer; Vito Llacqua; Hak Kan Lai; Matti Jantunen; Lucy Bayer-Oglesby; Nino Künzli



Time course of tinnitus development following noise exposure in mice  

PubMed Central

Gap-induced prepulse inhibition of acoustic startle (GPIAS) has been used in rats and mice to study the problem of tinnitus. The current study demonstrates that similar methods can be used to study the temporal development of tinnitus over time in middle-aged mice. Six-month-old mice on a mixed C57Bl6×129 background were anesthetized with isoflurane and exposed to unilateral noise (n=15), or sham exposure for controls (n=8), for one hour (16 kHz octave band signal, 116 dB SPL). Tinnitus was tested in eight different sound frequency bands before and at post-exposure time points of 1, 3–4, 7, 14, 21, and 30 days, and monthly thereafter until 7 months post exposure. Noise-exposed mice displayed a number of changes in GPIAS consistent with the presence of hyperacusis and tinnitus. Noise exposure was associated with acute tinnitus measured one day later at several frequencies at and above the exposure frequency center. Consistent, chronic tinnitus then emerged in the 24 kHz range. Several time points following noise exposure suggested evidence of hyperacusis, often followed temporally by the development of deficits in GPIAS (reflecting tinnitus). Temporal development of these changes following noise exposure are discussed in the context of the interactions between aging, noise exposure and the associated neurochemical changes that occur at early stages of auditory processing.

Turner, Jeremy; Larsen, Deb; Hughes, Larry; Moechars, Diederik; Shore, Susan



Time-distributed effect of exposure and infectious outbreaks  

PubMed Central

SUMMARY Extreme weather affects the timing and intensity of infectious outbreaks, the resurgence and redistribution of infections, and it causes disturbances in human-environment interactions. Environmental stressors with high thermoregulatory demands require susceptible populations to undergo physiological adaptive processes potentially compromising immune function and increasing susceptibility to infection. In assessing associations between environmental exposures and infectious diseases, failure to account for a latent period between time of exposure and time of disease manifestation may lead to severe underestimation of the effects. In a population, health effects of an episode of exposure are distributed over a range of time lags. To consider such time-distributed lags is a challenging task given that the length of a latent period varies from hours to months and depends on the type of pathogen, individual susceptibility to the pathogen, dose of exposure, route of transmission, and many other factors. The two main objectives of this communication are to introduce an approach to modeling time-distributed effect of exposures to infection cases and to demonstrate this approach in an analysis of the association between high ambient temperature and daily incidence of enterically transmitted infections. The study is supplemented with extensive simulations to examine model sensitivity to response magnitude, exposure frequency, and extent of latent period.

Naumova, Elena N.; MacNeill, Ian B.



Journey-time exposure to particulate air pollution  

Microsoft Academic Search

Journey-time exposures to particulate air pollution were investigated in Leicester, UK, between January and March 2005. Samples of TSP, PM10, PM2.5, and PM1 were simultaneously collected using light scattering devices whilst journeys were made by walking an in-car. Over a period of two months, 33 pairs of walking and in-car measurements were collected along two circular routes. Average exposures while

John Gulliver; David J. Briggs



Report of an image quality and dose audit according to directive 97/43/Euratom at Spanish private radiodiagnostics facilities.  


An audit of Spanish private medicine radiodiagnostics facilities has been carried out, based partly on Spanish legislation relating to European Directives on health protection against ionizing radiation risks in medical exposure. The study included an appraisal of infrastructure and equipment, and aspects of quality assurance and radiation protection, by means of data collected through surveys. Of the 51 centres audited, a sample of 24 X-ray rooms was chosen, then an external evaluation with regard to image quality and patient dose was performed, by an advisory board of radiologists and medical physicists. The methodology used was similar to that of the group of European Union experts in European dose evaluation and image quality trials. Chest, abdomen, lumbar spine and breast examinations were monitored. Doses were measured with thermoluminescent dosimeters. A third of the X-ray rooms evaluated reached or exceeded dose reference values, and in a third of the cases the image quality left considerable room for improvement. Breast and chest examinations showed themselves to be the hardest to perform, not only as a result of exceeding the reference doses, but also due to failure to meet good image quality standards. PMID:10365071

González, L; Vañó, E; Oliete, S; Manrique, J; Hernáez, J M; Lahuerta, J; Ruiz, J



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



Residence time and exposure time of sinking phytoplankton in the euphotic layer.  


The residence time of a sinking particle in the euphotic layer is usually defined as the time taken by this particle to reach for the first time the bottom of the euphotic layer. According to this definition, the concept of residence time does not take into account the fact that many cells leaving the euphotic layer at some time can re-enter the euphotic layer at a later time. Therefore, the exposure time in the surface layer, i.e. the total time spent by the particles in the euphotic layer irrespective of their possible excursions outside the surface layer, is a more relevant concept to diagnose the effect of diffusion on the survival of phytoplankton cells sinking through the water column. While increasing the diffusion coefficient can induce both a decrease or an increase of the residence time, the exposure time in the euphotic layer increases monotonically with the diffusion coefficient, at least when the settling velocity does not increase with depth. Turbulence is therefore shown to increase the total time spent by phytoplankton cells in the euphotic layer. The generalization of the concept of exposure time to take into account the variations of the light intensity with depth or the functional response of phytoplankton cells to irradiance leads to the definition of the concepts of light exposure and effective light exposure. The former provides a measure of the total light energy received by the cells during their cycling through the water column while the latter diagnose the potential growth rate. The exposure time, the light exposure and the effective light exposure can all be computed as the solution of a differential problem that generalizes the adjoint approach introduced by Delhez et al. (2004) for the residence time. A general analytical solution of the 1D steady-state version of this equation is derived from which the properties of the different diagnostic tools can be obtained. PMID:19825378

Delhez, Eric J M; Deleersnijder, Eric



Volatile dose and exposure time impact perception in neighboring plants.  


Volatiles emitted from stressed plants can induce resistance in healthy neighbors. It remains unknown, however, how plants perceive volatiles and convert them into internal signals. We exposed lima bean (Phaseolus lunatus L.) to different concentrations of either of two volatiles, nonanal and methyl salicylate (MeSA), over 6 or 24 h. Plant resistance to the bacterial pathogen, Pseudomonas syringae, was increased significantly after exposure to a headspace with two concentrations of nonanal for 6 h, and the same pattern emerged after an exposure over 24 h. By contrast, exposure to a low concentration of MeSA over 6 h did not significantly reduce bacterial infections, whereas exposure to the same concentration over 24 h significantly enhanced resistance. The dose-response relation that was apparent after 6 h of MeSA exposure disappeared in the 24 h treatment, in which the three tested concentrations caused indistinguishable, high levels of resistance to P. syringae. A low concentration of a potentially resistance-enhancing volatile sufficed to cause resistance to pathogens in the receiver plant only after long exposure time. Plant-plant signaling appears to involve the accumulation of volatiles in the receiver. PMID:22327276

Girón-Calva, P Saraí; Molina-Torres, Jorge; Heil, Martin




EPA Science Inventory

Accurate exposure classification tools are required to link exposure with health effects in epidemiological studies. Long-term, time-integrated exposure measures would be desirable to address the problem of developing appropriate residential childhood exposure classifications. ...


Novel monitor paradigm for real-time exposure assessment.  


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



Use of time to pregnancy to study environmental exposures  

SciTech Connect

There is need in reproductive epidemiology for sensitive and convenient screening tools that can be used to study environmental and occupational exposures. The measurement of fecundability (the probability of pregnancy in each cycle) by ascertaining how long it takes couples to conceive, may be useful for this purpose. Theoretically, exposures that interfere with any of the biologic processes involved in achieving pregnancy could lower fecundability among exposed men or women. To evaluate problems with collecting data on time to pregnancy, telephone interviews were conducted with nearly 700 pregnant women who reported having planned their pregnancies. Power curves were developed based on the distribution of time to pregnancy in the interviewed population. These curves indicate that relatively small sample sizes are sufficient for investigating an exposure. For example, the authors estimate that to detect a given 50% drop in mean fecundability with 80% power would require data from 55 exposed and 55 unexposed women who are pregnant. Disadvantages of using time to pregnancy as a reproductive endpoint include susceptibility to selection bias and need for data on several potential confounding variables. The next step in evaluating time to pregnancy as a reproductive endpoint is to apply it in studies of environmental or occupational exposures.

Baird, D.D.; Wilcox, A.J.; Weinberg, C.R.



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)



Time activity modelling of domestic exposures to radon.  


Radon gas occurs naturally in the environment with a variable distribution. In some areas radon concentrates sufficiently within the built environment that it is considered as a public health risk. It is possible, successfully, to reduce radon levels in the built environment, and it has been shown that such remediation programmes can be justified in terms of the costs and benefits accruing. However, the estimated dose received by people in their homes depends on the time spent indoors. The research presented here uses data derived from time activity surveys in Northamptonshire, together with radon data from a representative home, to model potential exposures for different population sub-groups. Average home occupancy ranged from 14.8h (probable error 2.5h) for students to 17.7 (3.1) h for adults; schoolchildren spent an average of 14.9 (1.2) h at home. Over a quarter of adults, however, were in the home for 22 h on more. These differences in occupancy patterns lead to substantial differences in radon exposure. In a home with an average hourly ground floor radon concentration of 467 Bqm(-3), modelled hourly average exposures ranged from ca. 250 Bqm(-3) for students and school children, to over 340 Bqm(-3), for women based at home. Modelled exposures show a non-linear association with total time spent at home, suggesting that exposure estimates based on linear models may provide misleading estimates of health risks from radon and the potential benefits of radon remediation. Highest hourly exposures are likely to be experienced by people with highly occupancy, living in single-storey, ground floor accommodation (for example, the elderly the infirm and non-working young mothers). Since these may be least aware of radon risks, and least able to take up remediation measures, they should be specifically targeted for radon monitoring and for assistance in remediation schemes. PMID:12654272

Briggs, D J; Denman, A R; Gulliver, J; Marley, R F; Kennedy, C A; Philips, P S; Field, K; Crockett, R M



Exposure Time Change Attack on Image Watermarking Systems  

NASA Astrophysics Data System (ADS)

We propose an effective attack based on exposure time change and image fusion, called ETC attack. First, the ETC attack simulates a set of images with different exposure time using the watermarked image. Then it applies an image fusion method to blend the multiple images mentioned above and thus generates a new image similar to the original one. In this paper, we describe the rationale of the attack. To illustrate the effect of the ETC attack, we present the results of the ETC attack against one watermarking scheme Iterative Watermarking Embedding. It can be shown that the ETC attack has an important impact on watermark decoding and detection, while not severely reducing the quality of the image.

Li, Kaituo; Zhang, Dan; Chen, De-Ren



EPA Science Inventory

Accurate exposure classification tools are required to link exposure with health effects in epidemiological studies. Although long-term integrated exposure measurements are a critical component of exposure assessment, the ability to include these measurements into epidemiologic...


The Real-Time Dust Exposures of Sodium Borate Workers: Examination of Exposure Variability  

Microsoft Academic Search

As part of an epidemiologic study of acute respiratory irritation, an assessment of the short term (TWA-0.25 hr) and daily (TWA-6 hr) dust and boron exposures of workers in a sodium borate production facility was undertaken. A real-time continuous aerosol monitor was used in an active mode with an in-line filter to collect a TWA-6 gravimetric sample with a datalogger

Susan R. Woskie; Peter Shen; Ellen A. Eisen; Martin H. Finkel; Thomas J. Smith; Ralph Smith; David H. Wegman



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.  


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



ETC-42: A VO Compliant Exposure Time Calculator  

NASA Astrophysics Data System (ADS)

We developed at CeSAM (Centre de donnéeS Astrophysiques de Marseille) from LAM a new Virtual Observatory compliant Exposure Time Calculator. This new ETC has been designed to facilitate the integration of new sites, instruments and sources by the user. It is not instrument-specific, but is based on generic XML input data. It is used in several project implementations (EUCLID, EELTs, OPTIMOS) covering a wide wavelength range (from NIR to UV). This paper focuses on the spectroscopic aspects of the tool and defines the structure of the application. It emphasizes the interoperability of the ETC and shows the added value for end users. Equations will be described in another paper in preparation

Surace, C.; Chabaud, P.-Y.; Leleu, G.; Apostolakos, N.; Lam Scientists



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



Children's Television Exposure and Behavioral and Social Outcomes at 5.5 Years: Does Timing of Exposure Matter?  

Microsoft Academic Search

BACKGROUND. The American Academy of Pediatrics recommends children 2 years of age limit daily media exposure to 1 to 2 hours and not have a television set in children's bedrooms. However, there are limited prospective studies to address how timing of media exposure influences children's health. OBJECTIVE. Our goal was to examine relations among children's early, concurrent, and sustained television

Kamila B. Mistry; Cynthia S. Minkovitz; Donna M. Strobino; Dina L. G. Borzekowski



Variations with time and age in the relative risks of solid cancer incidence after radiation exposure  

Microsoft Academic Search

The Japanese atomic bomb survivor cancer incidence dataset and data on five groups exposed to radiation for medical reasons in childhood are analysed and evidence found for a reduction in the radiation-induced relative risk of cancers other than leukaemia with increasing time since exposure and age at exposure. The rate of the reductions in relative risk with time since exposure

M. P. Little; F. de Vathaire; M. W. Charles; M. M. Hawkins; C. R. Muirhead



Using NIR spectroscopy to predict weathered wood exposure times  


... at quantifying the biodegradation process of wood during exposure to natural weathering. ... An additional 90 specimens were stored indoor to serve as controls. ... Multivariate statistical tools were used to further analyze NIR spectra data.


Adjusting timing of weathering test to account for seasonal variations in UV exposure  

Microsoft Academic Search

Satellite-derived UV climatology has been used to design a timetable for the outdoor UV exposure of polymeric material specimens. By pre-exposure computation, fixed time increments are transformed into a schedule with a predicted average accumulation of UV dose. The method was applied to produce a timetable for an ongoing exposure programme in a network of seven European test sites over

A. Heikkilä; A. Tanskanen; P. Kärhä; K. Hanhi



Understanding Online Interruption-Based Advertising: Impacts of Exposure Timing, Advertising Intent, and Brand Image  

Microsoft Academic Search

Interruption-based advertising has gained prominence in the online channel. Yet, little attention has been paid to deriving design principles and conceptualizations for online interruption-based advertising. This paper examines three novel design factors related to this phenomenon, namely, exposure timing, advertising intent, and brand image. Exposure timing pertains to the time by which the advertisement (ad) is launched within a website.

Jason C. F. Chan; Zhenhui Jiang; Bernard C. Y. Tan



Measuring potential exposure to environmental pollutants: time spent with soil and time spent outdoors.  


In 1994-1995, the Electric Power Resource Institute (EPRI) undertook a major national survey of time in microenvironments with 1200 respondents aged 18 and older. It did so using a methodology that minimized the problems of respondent recall and reporting by the use of a "time diary," in which survey respondents reported in detail about their actual activities "yesterday" including time spent outdoors. In addition, respondents were asked questions about the extent of contact with soil they had on that day. Significant proportions (20%) of the American public reported coming in direct contact with soil on a typical day and those who did come in contact were exposed for about 1.7 h per day; some 6% of the public reported being exposed for more than 2 h on the day in question, mainly by hand (although 3% of respondents reported soil contact with their head or face). As expected, men reported far more soil contact than women; surprisingly few consistent differences were found by age, or by marital status, parental status or employment status. Contrary to expectations, higher contact was not reported by minorities, or by less educated or less affluent respondents. Moreover, these patterns generally remained unchanged after adjustment for other demographic predictors. More as expected, higher exposure was reported in the Spring months, on weekends, and in rural areas and in the South and West regions of the country, patterns again largely unaffected by multivariate controls for other predictors. In general, while certain predictors of soil exposure were much the same for time spent outdoors, there were some notable exceptions. PMID:10981728

Robinson, J P; Silvers, A


Pre-exposure chemoprophylaxis for HIV: It is time  

PubMed Central

The HIV-1 plague continues unabatedly across sub-Saharan Africa. In Botswana and Swaziland, nearly 40% of the entire adult population is already infected. No current program is capable of slowing the advancing tide. An effective vaccine and widespread treatment are years, if not, decades away. In this most urgent situation, I propose that pre-exposure chemoprophylaxis be studied as a means to reduce the spread of HIV-1 among at-risk individuals.

Smith, Stephen M



Farmworker Children's Residential Non-Dietary Exposure Estimates from Micro-Level Activity Time Series  

PubMed Central

Farmworkers’ children may have increased pesticide exposure through dermal absorption and non-dietary ingestion, routes that are difficult to measure and model. The Cumulative Aggregate Simulation of Exposure (CASE) model, integrates the complexity of human behavior and variability of exposure processes by combining micro-level activity time series (MLATS) and mechanistic exposure equations. CASE was used to estimate residential non-dietary organophosphate pesticide exposure (i.e., inhalation, dermal, and non-dietary ingestion) to California farmworker children and evaluate the micro-activity approach. MLATS collected from children and distributions developed from pesticide measurements in farmworkers’ residences served as inputs. While estimated diazinon exposure was greater for inhalation, chlorpyrifos exposure was greater for the other routes. Greater variability existed between children (?B2=0.22?0.39) than within each child’s simulations (?W2=0.01?0.02) for dermal and non-dietary ingestion. Dermal exposure simulations were not significantly different than measured values from dosimeters worn by the children. Non-dietary ingestion exposure estimates were comparable to duplicate diet measurements, indicating this route may contribute substantially to aggregate exposure. The results suggest the importance of the micro-activity approach for estimating non-dietary exposure. Other methods may underestimate exposure via these routes. Model simulations can be used to identify at-risk children and target intervention strategies.




Influence of temperature and storage time after light exposure on the quinine monohydrochloride chemical actinometric system.  


The ICH guideline on photostability has proposed quinine monohydrochloride chemical actinometric system as a standard method for measuring light exposure during photostability testing. A change in the absorption at 400 nm of quinine monohydrochloride after light exposure corresponds to a defined dose of light. The present work investigated the effect of temperature, light exposure level and the dark reactions following light exposure on the change of absorbance obtained. The change in the absorbance was linear with respect to time, the rate increased threefold in the temperature range of 25-52 degrees C, and the calculated activation energy was 30 kJ/mol as calculated by the Arrhenius equation. For the dark reactions the change in absorbance was non-linear with respect to time. The rate of the dark reactions was smaller than during light exposure and dependent on the light exposure level prior to the dark reactions. The calculated activation energy of the dark reactions was 18 kJ/mol when calculated by the Arrhenius equation on the initial reaction rates. The different activation energy of the light reaction and the dark reactions indicated different degradation patterns of the two reactions. The present study shows that the absorbance change of quinine monohydrochloride chemical actinometric system is dependent on temperature during light exposure and on storage time and storage temperature after light exposure. The method proposed in the ICH guideline should therefore be optimized in terms of definition of temperature and limitations in storage time after light exposure. PMID:10594390

Christensen, K L; Christensen, J O; Frokjaer, S; Langballe, P; Hansen, L L



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


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



The role of CO2 variability and exposure time for biological impacts of ocean acidification  

NASA Astrophysics Data System (ADS)

impacts of ocean acidification have mostly been studied using future levels of CO2 without consideration of natural variability or how this modulates both duration and magnitude of CO2 exposure. Here we combine results from laboratory studies on coral reef fish with diurnal in situ CO2 data from a shallow coral reef, to demonstrate how natural variability alters exposure times for marine organisms under increasingly high-CO2 conditions. Large in situ CO2 variability already results in exposure of coral reef fish to short-term CO2 levels higher than laboratory-derived critical CO2 levels (~600 µatm). However, we suggest that the in situ exposure time is presently insufficient to induce negative effects observed in laboratory studies. Our results suggest that both exposure time and the magnitude of CO2 levels will be important in determining the response of organisms to future ocean acidification, where both will increase markedly with future increases in CO2.

Shaw, Emily C.; Munday, Philip L.; McNeil, Ben I.



Estimating sampling frequency in pollen exposure assessment over time.  


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. PMID:16951756

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



Time course of airway remodelling after an acute chlorine gas exposure in mice  

PubMed Central

Accidental chlorine (Cl2) gas inhalation is a common cause of acute airway injury. However, little is known about the kinetics of airway injury and repair after Cl2 exposure. We investigated the time course of airway epithelial damage and repair in mice after a single exposure to a high concentration of Cl2 gas. Mice were exposed to 800 ppm Cl2 gas for 5 minutes and studied from 12 hrs to 10 days post-exposure. The acute injury phase after Cl2 exposure (? 24 hrs post-exposure) was characterized by airway epithelial cell apoptosis (increased TUNEL staining) and sloughing, elevated protein in bronchoalveolar lavage fluid, and a modest increase in airway responses to methacholine. The repair phase after Cl2 exposure was characterized by increased airway epithelial cell proliferation, measured by immunoreactive proliferating cell nuclear antigen (PCNA), with maximal proliferation occurring 5 days after Cl2 exposure. At 10 days after Cl2 exposure the airway smooth muscle mass was increased relative to controls, suggestive of airway smooth muscle hyperplasia and there was evidence of airway fibrosis. No increase in goblet cells occurred at any time point. We conclude that a single exposure of mice to Cl2 gas causes acute changes in lung function, including pulmonary responsiveness to methacholine challenge, associated with airway damage, followed by subsequent repair and airway remodelling.

Tuck, Stephanie A; Ramos-Barbon, David; Campbell, Holly; McGovern, Toby; Karmouty-Quintana, Harry; Martin, James G



The Multi-Motion-Overlap Strategy to Minimize Time between Continuous Exposure Scans for Wafer Stage  

Microsoft Academic Search

During the exposure process, the transitional time between continuous scans does not produce production efficiency in which no scanning occurs. This inefficiency increases the total time to manufacture a chip on a wafer and limits the productivity of wafer in a production process. To optimize the transitional step time, we investigated the motion trajectory planning along the scanning direction for

Hai-Hong Pan; Xiao-Qing Li; Yun-Fei Zhou



Influence of Exposure Time and Pupil Size on a Shack-Hartmann Metric of Forward Scatter  

PubMed Central

PURPOSE: To determine the influence of exposure time and pupil size on a Shack-Hartmann (S/H) derived metric of forward scatter (MAX_SD) using a physical model of nuclear cataract. METHODS: A physical model eye was developed and mounted to a S/H wavefront sensor. The eye model consisted of a lens, variable pupil, simulated cataract, and retina. Located behind the pupil, a cuvette contained one of five polystyrene microsphere solutions simulating five levels of nuclear cataract severity. Cataract severity was described using a S/H derived metric of forward scatter (MAX_SD), which measures aspects of forward scatter contained in the S/H lenslet point spread functions (PSF). To determine the impact of exposure time and pupil size, measurements of MAX_SD were regressed against cataract severity for three different exposure times and three different pupil sizes. RESULTS: MAX_SD was well correlated to cataract severity. Exposure time had the largest influence, and pupil size had the smallest influence on the forward scatter metric. When pupil size and exposure time were allowed to vary and image saturation was allowed to occur, MAX_SD explained 83% of the variance in cataract severity. Excluding images where saturation occurred, holding optimal exposure time constant, and varying pupil size, MAX_SD explained 97% of the variance in cataract severity. CONCLUSIONS: The ability of the forward scatter metric derived from S/H measurements to predict cataract severity for a longitudinal study is optimized by selecting a patient-specific exposure at the initial cataract assessment to avoid saturation and maximize the dynamic range of the system. This patient-specific exposure should be used in all future visits.

Donnelly, William J.; Applegate, Raymond A.



Graphic-processing-unit-accelerated real-time exposure fusion method using pixel-level optimal exposure criterion  

NASA Astrophysics Data System (ADS)

High dynamic range (HDR) imaging is an important and challenging research topic in computational photography. A simple but effective image fusion method is proposed to accomplish the multi-exposure image composition in both static and dynamic scenes. The foundation of the proposed method is an experiential criterion that optimizes the exposure that occurs at a dramatic alteration point in the low dynamic range image sequence (LDRI). To extract these well-exposed pixel vectors, each pixel curve formed by the pixel vectors at same position along all frames in the LDRIs is first preprocessed by the chord length parameterization. Then a single high-quality pseudo-HDR image can be extracted directly and efficiently from the LDRIs using a pixel-level fusion index matrix derived from the first- and second-order difference quotients of the preprocessed pixel curves. The main advantage of the proposed method is its use of a single independent pixel in computing. It is highly parallel, allowing a graphic processing unit-based, real-time implementation. The experiments on various scenes discussed here indicate that the proposed exposure fusion method can combine a large image sequence with 10 megapixels into a visually compelling pseudo-HDR image at a rate of 30 frames/s on a consumer hardware.

Zhang, Jun; Hu, Shiqiang



Long time exposure digital in-line holography for 3-D particle trajectography.  


One advantage of digital in-line holography is the ability for a user to know the 3-D location of a moving particle recorded at a given time. When the time exposure is much larger than the time required for grabbing the particle image at a given location, the diffraction pattern is spread along the trajectory of this particle. This can be seen as a convolution between the diffraction pattern and a blurring function resulting from the motion of the particle during the camera exposure. This article shows that the reconstruction of holograms recorded under such conditions exhibit traces that could be processed for extracting 3D trajectories. PMID:24104265

Lebrun, D; Méès, L; Fréchou, D; Coëtmellec, S; Brunel, M; Allano, D



Residence time and exposure time of sinking phytoplankton in the euphotic layer  

Microsoft Academic Search

The residence time of a sinking particle in the euphotic layer is usually defined as the time taken by this particle to reach for the first time the bottom of the euphotic layer. According to this definition, the concept of residence time does not take into account the fact that many cells leaving the euphotic layer at some time can

Éric J. M. Delhez; Eric Deleersnijder



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...


Time to pregnancy and occupational exposure to pesticides in fruit growers in The Netherlands.  

PubMed Central

OBJECTIVES--Although pesticides are regularly used in agriculture, relatively little is known about possible adverse health effects, especially reproductive effects, due to occupational exposure. This explorative study investigates the relation between exposure of the fruit grower to pesticides and fecundability (probability of pregnancy) in a population of fruit growers. METHODS--The analysis is based on self reported data and includes 91 pregnancies during 1978-1990 of 43 couples. Cox' proportional hazards model was used to analyse time to pregnancy after correction for gravidity and consultation with a physician for fertility problems. RESULTS AND CONCLUSIONS--Application of pesticides solely by the owner was associated with a long time to pregnancy, resulting in a fecundability ratio of 0.46 (95% confidence interval (95% CI) 0.28-0.77). Similarly a low spraying velocity (< or = 1.5 hectares/h) resulted in a fecundability ratio of 0.47 (95% CI 0.29-0.76) and is associated with the use of older spraying techniques and tractors without a cabin. These factors were assumed to cause high exposure, which was confirmed by exposure measurements in the field. The effect of high exposure was mainly apparent if the couple had intended to become pregnant in the period from March-November (fecundability ratio 0.42, 95% CI 0.20-0.92). This is the period in which pesticides are applied. Out of the spraying season the effect of a high exposure was absent (fecundability ratio 0.82, 95% CI 0.33-2.02). In the high exposure group 28% of the pregnancies had been preceded by consulting a physician because of fertility problems, compared with 8% in the low exposure group. These findings indicate that an adverse effect of exposure to pesticides on fecundability is likely.

de Cock, J; Westveer, K; Heederik, D; te Velde, E; van Kooij, R



Recurrent studies of chloride ingress in uncracked marine concrete at various exposure times and elevations  

SciTech Connect

Uncracked reinforced concrete slabs were field exposed mounted on a floating pontoon and partly submerged for 5 years at the Swedish west coast. The total chloride ingress was analyzed at various exposure times at 3 elevations representing a submerged, a splash, and an atmospheric exposure zone. The concrete mixtures varied in w/c ratio, type of cement, and amount and type of pozzolan used in the binder. The data is unique as it represents recurrently measured total chloride penetration profiles at various exposure ages, providing a foundation for the prediction of chloride ingress in concrete in a given environment. The results after 5 years of exposure confirmed the expected inverse relationship between water-to-binder ratio and chloride ingress. The use of 5--10% silica fume in the binder had a very positive effect on reducing the chloride ingress, but little or no benefit at all was found for concrete with fly ash in the binder as compared to the use of 5% silica fume. The chloride penetration rate as expressed by a calculated effective chloride diffusivity has a tendency to decrease over time. High-performance concrete with w/c {le} 0.4 and a minimum of 5% silica fume added as a well dispersed slurry exhibited an effective chloride diffusivity in the range of 1 {times} 10{sup {minus}13} to 5 {times} 10{sup {minus}13} m{sup 2}/s after 5 years exposure in the splash zone.

Sandburg, P. [Lund Inst. of Tech. (Sweden). Div. of Building Materials; Tang, L. [Swedish National Testing and Research Inst., Boraes (Sweden); Andersen, A. [Chalmers Univ., Goeteborg (Sweden). Div. of Building Materials



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.



Highly time-variable exposure to chemicals--toward an assessment strategy.  


Organisms in the environment experience fluctuating, pulsed, or intermittent exposure to pollutants. Accounting for effects of such exposures is an important challenge for environmental risk assessment, particularly given the simplified design of standard ecotoxicity tests. Dynamic simulation using toxicokinetic-toxicodynamic (TK-TD) models describes the processes that link exposure with effects in an organism and provides a basis for extrapolation to a range of exposure scenarios. In so doing, TK-TD modeling makes the risk assessment more robust and aids use and interpretation of experimental data. Toxicokinetic-toxicodynamic models are well-developed for predicting survival of individual organisms and are increasingly applied to sublethal endpoints. In the latter case particularly, linkage to individual-based models (IBMs) allows extrapolation to population level as well as accounting for differences in effects of toxicant exposure at different stages in the life cycle. Extrapolation between species remains an important constraint because there is currently no systematic understanding of species traits that cause differences in the relevant processes. Toxicokinetic-toxicodynamic models allow interrogation of exposure profiles to determine intrinsic toxicity potential rather than using absolute maximum concentrations or time-weighted averages as surrogates. A decision scheme is proposed to guide selection of risk assessment approaches using dose extrapolation based on Haber's Law, TK-TD models, and/or IBMs depending on the nature of toxic effect and timing in relation to life history. PMID:23564608

Ashauer, Roman; Brown, Colin D



Assessing the effects of exposure timing on biomarker expression using 17beta-estradiol.  


Temporal and spatial variability in estrogenicity has been documented for many treated wastewater effluents with the consequences of this variability on the expression of biomarkers of endocrine disruption being largely unknown. Laboratory exposure studies usually utilize constant exposure concentrations which may produce biological effects that differ from those observed in organisms exposed in natural environments. In this study, we investigated the effects of differential timing of exposures with 17beta-estradiol (E2) on a range of fathead minnow biomarkers to simulate diverse environmentally relevant exposure profiles. Two 21-day, replicate experiments were performed exposing mature male fathead minnows to E2 at time-weighted mean concentrations (similar average exposure to the contaminant during the 21-day exposure period; 17ng E2/L experiment 1; 12ng E2/L experiment 2) comparable to E2 equivalency values (EEQ) reported for several anthropogenically altered environments. A comparable time-weighted mean concentration of E2 was applied to five treatments which varied in the daily application schema: E2 was either applied at a steady rate (ST), in a gradual decreasing concentration (HI), a gradual increasing concentration (LO), applied intermittently (IN), or at a randomly varying concentration (VA). We assessed a range of widely used physiological (vitellogenin mRNA induction and plasma concentrations), anatomical (body and organ indices, secondary sex characteristics, and histopathology), and behavioral (nest holding) biomarkers reported to change following exposure to endocrine active compounds (EACs). All treatments responded with a rise in plasma vitellogenin concentration when compared with the ethanol carrier control. Predicatively, vitellogenin mRNA induction, which tracked closely with plasma vitellogenin concentrations in most treatments was not elevated in the HI treatment, presumably due to the lack of E2 exposure immediately prior to analysis. The ability of treatment male fish to hold nest sites in direct competition with control males was sensitive to E2 exposure and did yield statistically significant differences between treatments and carrier control. Other biological endpoints assessed in this study (organosomatic indices, secondary sex characteristics) varied little between treatments and controls. This study indicates that a broad suite of endpoints is necessary to fully assess the biological consequences of fish exposure to estrogens and that for at least field studies, a combination of vitellogenin mRNA and plasma vitellogenin analysis are most promising in deciphering exposure histories of wild-caught and caged fishes. PMID:20005582

Hyndman, K M; Biales, A; Bartell, S E; Schoenfuss, H L



Risk of thyroid cancer after adult radiation exposure: time to re-assess?  


To protect workers and the public from the harmful effects of radiation exposure, it is important that regulatory bodies and advisory organizations have as complete an understanding as possible of the risks according to gender, age at exposure, time since exposure, health status and other related variables. The 2011 disaster at the Fukushima Daiichi nuclear power plant complex again alerted the world to the possibility that large groups, including many adults, can be exposed to (131)I, it reminds us that it is important to understand the effect of age at exposure on cancer risk to achieve effective radiation protection and to plan for responses to future nuclear accidents or terrorist events involving radiation. PMID:23252377

Mabuchi, Kiyohiko; Hatch, Maureen; Little, Mark P; Linet, Martha S; Simon, Steven L



Time lines and computer-based visual editing: new techniques for assessing exposure in epidemiologic studies  

Microsoft Academic Search

We describe a time-line-based methodology for collecting exposure data for epidemiologic studies and for processing these data for statistical analysis with readily available software for the personal computer. The four components to this approach are: (1) collecting data in a memory-enhancing time-line format; (2) entering data from time lines into a computer database and editing them; (3) making a quantitative




Effects of exposure time, material type, and granular pesticide on glove contamination.  


Chemical-resistant gloves are recommended for pesticide applicators to reduce their exposure to agricultural chemicals. In this research, three chemical-resistant glove materials-nitrile, neoprene, and barrier laminate-were studied in relation to contamination with granular terbufos and tefluthrin. Surfaces of specimens backed with alpha cellulose were contaminated with 300 mg of either granular terbufos or tefluthrin for 1-, 2-, 4-, 8-, 16-, and 24-h time periods in petri dishes in the laboratory. Residues were extracted using ethyl acetate for terbufos and iso-octane for tefluthrin in test tubes for 24 h. Analysis of extracts by gas chromatograph and statistical analysis of the data showed that contamination levels varied with the time of exposure, material type, and pesticide used. Pesticide was not detected in the alpha cellulose even after 24 h contamination time. A linear relationship was found between contamination level and exposure time for terbufos in the three materials, with longer exposure times causing higher contamination levels. Contamination of nitrile was significantly less than neoprene or barrier laminate. Exposed glove materials contained higher levels of contamination of terbufos than tefluthrin. PMID:11598792

Guo, C; Stone, J; Stahr, H M; Shelley, M



Guidelines on the Risk and Time to Frostbite during Exposure to Cold Winds  

Microsoft Academic Search

The objective of the present study was to define the risk and the time required to develop frostnip on the face during exposure to cold winds. Twelve subjects (6 males and 6 females) were exposed to sixteen 45 min tests where the wind intensity varied between 0, 16 and 32 km\\/h. The tests were conducted at 0, -10, -20, -30,

Michel B. Ducharme; Dragan Brajkovic


First experiences with a high sensitive videocamera with internal multiframe exposure time  

NASA Astrophysics Data System (ADS)

This is a short report about the use of the high sensitive black-white video camera MTV-12V1-EX that allows to increase the sensitivity about 2 magnitudes in normal video mode and about 4 magnitudes by using the internal selectable multiframe exposure time with 0.3 sec time resolution (compared with sensitivity of simple black-white video cameras). A video record demonstrates some occultation events and starfields.

Rothe, Wolfgang



Effect of ceramic veneer opacity and exposure time on the polymerization efficiency of resin cements.  


The objective of this study was to determine the degree of conversion (DC), hardness (H), and modulus of elasticity (E) of a dual-cured resin cement, a light-cured resin cement, and a flowable resin cured through opaque or translucent ceramic with different exposure times. RelyX ARC (dual), RelyX Veneer (light-cured), and Filtek Z350 Flow resin specimens 0.5 mm thick were cured for 40, 80, and 120 seconds through 1-mm thick translucent or opaque feldspathic ceramic disks (n=10). The specimens were stored at 37°C for 24 hours. Half of each specimen was used to test the DC and the other half to test H and E. The DC was determined in a Fourier transform infrared spectrometer in absorbance mode at peaks of 1638 cm(-1) and 1610 cm(-1). H and E were determined using nanoindentation with one loading cycle and a maximum load of 400 mN. The data were analyzed with three-way analysis of variance (ANOVA), the Games-Howell test, and the Pearson correlation test (?=0.05). Statistically significant differences were found for all three factors (material, opacity, and exposure time), as well as interaction between them. The opaque ceramic resulted in lower DC, H, and E than the translucent ceramic for an exposure time of 40 seconds. An exposure time of 120 seconds resulted in a similar DC for all materials, irrespective of the opacity of the ceramic. Materials cured for 120 seconds had higher H and E than those cured for 40 seconds. The exposure time and opacity of the ceramic exerted an influence on the DC, H, and E of the materials evaluated. PMID:22313282

Archegas, Lucí Regina Panka; de Menezes Caldas, Danillo Biazzetto; Rached, rodrigo Nunes; Soares, Paulo; Souza, Evelise Machado



Time course of permeability changes and PMN flux in rat trachea following O3 exposure  

SciTech Connect

Changes in rat tracheal epithelial permeability and polymorphonuclear leukocyte (PMN) populations during a 24-hr time period following a 3-hr exposure to 0.8 ppm ozone (O3) were investigated. An increase in permeability to 99mTc-diethylene-triaminepentaacetate (DTPA) occurred immediately after the exposure, peaked at the 8-hr time point and decreased to control level by 24 hr. For correlation with tracheal permeability, tracheal cross sections were stained with naphthol AS-D chloroacetate and PMNs were scored by their location as well as staining characteristics (positive or negative). The total PMN population remained at the control value at the 0-, 4-, and 8-hr time points, and increased at 12 hr, followed by a rapid decline to below the control value for the remaining time points. There was a shift at the 8-hr time point in the population location, from the vasculature to the interstitium, which returned to control values at 12 hr. The percentage stained PMNs increased significantly at 16 hr while remaining at control values for all other time points. The data reveal that there is a significant increase in tracheal epithelial permeability immediately after the exposure, but the overall increase in the PMN population is preceded by a lag phase. A decrease in the vascular pool of PMNs concomitant with an increase in the interstitial pool of PMNs suggests their migration from blood to the interstitium after ozone exposure. These data indicate that while PMNs may play a role in permeability changes of tracheal epithelium, the initiation is most likely due to other factors.

Young, C.; Bhalla, D.K. (Community and Environmental Medicine, University of California, Irvine (United States))



Seasonal and geographic effects on predicting personal exposure to nitrogen dioxide by time-weighted microenvironmental model  

NASA Astrophysics Data System (ADS)

The purposes of this study were to investigate the impact of microenvironment concentrations on personal exposure by season and city, and to develop statistical models to predict personal exposure to nitrogen dioxide (NO2). Personal exposures, residential indoor, residential outdoor and workplace indoor levels of NO2 were measured in four cities in Korea (Seoul, Daegu, Asan and Suncheon) using a passive sampler for five weekdays. The measurements were conducted in summer and winter during 2008-2009. Average personal NO2 exposures were 20.5 ppb in summer and 18.6 ppb in winter. The average personal exposures of NO2 and residential indoor levels were the highest in Seoul and the lowest in Suncheon both summer and winter. Personal exposure was significantly different by season. Personal exposure was significantly correlated with residential indoor concentration in all cities. The personal exposure estimated by residential indoor, workplace indoor and outdoor levels explained 38% and 41% of the measured personal exposure variance in summer and winter, respectively. The low correlation may be due to the longer time spent in other microenvironments in the Korean population. Personal exposure was significantly correlated with working day and city. Correlation between the estimated personal exposure and measured personal exposure was significantly associated with the season and city. The model can provide reasonable estimation of population exposure with appropriate microenvironmental concentrations and time activity data. However, season- and city-specific models should be considered.

Lee, Kiyoung; Yeom, Jiseon; Yoon, Chungsik; Yang, Wonho; Son, Bu-Soon; Jeon, Jun Min; Yu, Seung-Do; Park, Choong-Hee



Attenuation of hypoxic ventilation by hyperbaric O2: effects of pressure and exposure time.  


Hyperoxia affects O2 chemoreception in the highly perfused carotid bodies and causes a reduction of the ventilatory hypoxic drive (HD) as was shown for anesthetized cats and awake rats. We looked for a quantitative description of such an effect on HD as a function of both O2 pressure and exposure duration. Ventilation of rats was measured using the barometric method before and after hyperbaric O2 (HBO) exposure, at either air, 80% O2, or 4% O2. We used three exposure durations: 180, 550 and 900 min. The O2 pressure ranged between 1.2 and 3.0 ATA. At each time duration we used four to five groups of rats at a range of O2 pressures that yielded the full scale of effect on HD but avoided obvious lasting difficulties in breathing. HBO caused a reduction of breathing frequency and elevation of tidal volume in both air and 80% O2 but almost no change in minute ventilation. Hypoxic minute ventilation (4% O2) decreased after HBO, mainly through reduced frequency. HD was described by a power function of O2 pressure for each HBO duration. HD did not decline below 20% of the full control response. Ventilatory HD diminution is pictured as a function of both O2 pressure and HBO duration. The dependency of HD on exposure time and on pressure is similar to other known toxic effects of HBO. PMID:2708214

Liberzon, I; Arieli, R; Kerem, D



Intimate Partner Violence Exposure and Change in Women's Physical Symptoms Over Time  

PubMed Central

OBJECTIVE To examine the change in women’s self-reported physical symptoms over 2 time points in relation to intimate partner violence (IPV) exposure. DESIGN Prospective interview study of 267 women recruited from 8 health care settings and surrounding communities in Metropolitan Boston. METHODS We created sums of somatic symptoms at 2 separate time points (a mean of 9.5 months apart) using items from a modified PHQ-15. A measure of symptom change was computed to measure the net change in symptoms over time. A negative score indicated reduction in total symptoms, or improvement. Exposure to IPV was measured at both time points. RESULTS Women who reported ongoing IPV across both time points experienced an increase in their overall physical symptoms compared to women with past abuse (p?=?.0054) and no abuse (p?=?.0006). In multivariate regression analysis, ongoing IPV at both time points was a statistically significant predictor of symptom change. This relationship persisted even after controlling for age, race, education, depression, self-report of co-morbid illness, and history of child abuse and prior sexual assault (p?=?.0076). CONCLUSIONS Women exposed to ongoing IPV report increased physical symptoms over time. Clinicians should consider the possibility of IPV in patients who remain persistently symptomatic over time in addition to employing more traditional means of detecting IPV.

Wittenberg, Eve; Ganz, Michael L.; Williams, Corrine M.; McCloskey, Laura A.



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.



Parathyroid hormone exerts disparate effects on osteoblast differentiation depending on exposure time in rat osteoblastic cells.  

PubMed Central

It has been reported that PTH exerts bone-forming effects in vivo when administered intermittently. In the present study, the anabolic effects of PTH(1-34) on osteoblast differentiation were examined in vitro. Osteoblastic cells isolated from newborn rat calvaria were cyclically treated with PTH(1-34) for the first few hours of each 48-h incubation cycle. When osteoblastic cells were intermittently exposed to PTH only for the first hour of each 48-h incubation cycle and cultured for the remainder of the cycle without the hormone, osteoblast differentiation was inhibited by suppressing alkaline phosphatase activity, bone nodule formation, and mRNA expression of alkaline phosphatase, osteocalcin, and PTH/PTHrP receptor. Experiments using inhibitors and stimulators of cAMP/protein kinase A (PKA) and Ca2+/PKC demonstrated that cAMP/PKA was the major signal transduction system in the inhibitory action of PTH. In contrast, the intermittent exposure to PTH for the first 6 h of each 48-h cycle stimulated osteoblast differentiation. Both cAMP/ PKA and Ca2+/PKC systems appeared to be involved cooperatively in this anabolic effect. Continuous exposure to PTH during the 48-h incubation cycle strongly inhibited osteoblast differentiation. Although both cAMP/PKA and Ca2+/PKC were involved in the effect of continuous exposure to PTH, they appeared to act independently. A neutralizing antibody against IGF-I blocked the stimulatory effect on alkaline phosphatase activity and the expression of osteocalcin mRNA induced by the 6-h intermittent exposure. The inhibitory effect induced by the 1-h intermittent exposure was not affected by anti-IGF-I antibody. These results suggest that PTH has diverse effects on osteoblast differentiation depending on the exposure time in vitro mediated through different signal transduction systems. These in vitro findings explain at least in part the in vivo action of PTH that varies with the mode of administration.

Ishizuya, T; Yokose, S; Hori, M; Noda, T; Suda, T; Yoshiki, S; Yamaguchi, A



Acid Diffusion Length Corresponding to Post Exposure Bake Time and Temperature  

NASA Astrophysics Data System (ADS)

The post exposure bake (PEB) step in lithography is important for fabricating good patterns when a chemically amplified resist is used. Hydrogen ions or acid is generated by a photoacid generator through light exposure. The generated acid diffuses and acts as a catalyst for chemical amplification during the PEB step. Acid diffusion length (ADL) affects the deprotection of a resist polymer, such that linewidth is affected by ADL. The common parameter that determines ADL is the acid diffusion coefficient D; thus, we must determine D accurately in order to obtain the actual linewidth. However, D cannot be unambiguously determined for the actual PEB temperature and time. ADL has become a critical factor for 100 nm patterns and below. Thus, the accurate ADL determination becomes an important issue for better linewidth prediction by simulation. To match ADL and PEB time and temperature, we attempted to determine the relationship between the PEB parameters and ADL. As a result, we obtained a reasonable ADL.

Park, Jin-Back; Kim, Sung-Hyuck; Kim, Sung-Jin; Cho, Jung-Hyuk; Oh, Hye-Keun



Hepatitis C virus epitope exposure and neutralization by antibodies is affected by time and temperature  

PubMed Central

A recent study with flaviviruses suggested that structural dynamics of the virion impact antibody neutralization via exposure of ostensibly cryptic epitopes. To determine whether this holds true for the distantly related hepatitis C virus (HCV), whose neutralizing epitopes may be obscured by a glycan shield, apolipoprotein interactions, and the hypervariable region on the E2 envelope protein, we assessed how time and temperature of pre-incubation altered monoclonal antibody (MAb) neutralization of HCV. Notably, several MAbs showed increased inhibitory activity when pre-binding was performed at 37°C or after longer pre-incubation periods, and a corresponding loss-of-neutralization was observed when pre-binding was performed at 4°C. A similar profile of changes was observed with acute and chronic phase sera from HCV-infected patients. Our data suggest that time and temperature of incubation modulate epitope exposure on the conformational ensembles of HCV virions and thus, alter the potency of antibody neutralization.

Sabo, Michelle C.; Luca, Vincent C.; Ray, Stuart C.; Bukh, Jens; Fremont, Daved H.; Diamond, Michael S.



Changes in organic matter–mineral interactions for marine sediments with varying oxygen exposure times  

Microsoft Academic Search

Density fractionation, X-ray photoelectron spectroscopy (XPS) and amino acid analyses were used to evaluate the physical form of preserved organic carbon (OC) in sediments from transects in the north east Pacific Ocean off the Mexican (Mazatlan) and Washington coasts. Low density (i.e. mineral-free) organic material dominated the OC in sediments with very short oxygen exposure times (OET <1 yr; total

Thorarinn S. Arnarson; Richard G. Keil



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



Visualisation of blood and lymphatic vessels with increasing exposure time of the detector  

NASA Astrophysics Data System (ADS)

We describe the laser speckle contrast method for simultaneous noninvasive imaging of blood and lymphatic vessels of living organisms, based on increasing detector exposure time. In contrast to standard methods of fluorescent angiography, this technique of vascular bed imaging and lymphatic and blood vessel demarcation does not employ toxic fluorescent markers. The method is particularly promising with respect to the physiology of the cardiovascular system under in vivo conditions.

Kalchenko, V. V.; Kuznetsov, Yu L.; Meglinski, I. V.



Real-time measurement of dust in the workplace using video exposure monitoring: Farming to pharmaceuticals  

NASA Astrophysics Data System (ADS)

Real-time, photometric, portable dust monitors have been employed for video exposure monitoring (VEM) to measure and highlight dust levels generated by work activities, illustrate dust control techniques, and demonstrate good practice. Two workplaces, presenting different challenges for measurement, were used to illustrate the capabilities of VEM: (a) poultry farming activities and (b) powder transfer operations in a pharmaceutical company. For the poultry farm work, the real-time monitors were calibrated with respect to the respirable and inhalable dust concentrations using cyclone and IOM reference samplers respectively. Different rankings of exposure for typical activities were found on the small farm studied here compared to previous exposure measurements at larger poultry farms: these were mainly attributed to the different scales of operation. Large variations in the ratios of respirable, inhalable and real-time monitor TWA concentrations of poultry farm dust for various activities were found. This has implications for the calibration of light-scattering dust monitors with respect to inhalable dust concentration. In the pharmaceutical application, the effectiveness of a curtain barrier for dust control when dispensing powder in a downflow booth was rapidly demonstrated.

Walsh, P. T.; Forth, A. R.; Clark, R. D. R.; Dowker, K. P.; Thorpe, A.



Stellar scintillation in the short exposure regime and atmospheric coherence time evaluation  

NASA Astrophysics Data System (ADS)

Aims: Accurately measuring the atmospheric coherence time is still a significant problem despite a variety of applicable methods. The Multi-Aperture Scintillation Sensor (MASS) designed for the vertical profiling of optical turbulence also provides a measurements of coherence time, but its results were found to be biased. Hence there is a need for a more robust method to determine ?0. Methods: The effect of smoothing the stellar scintillation by a finite exposure of the detector is considered. The short exposure regime is described and its limits are defined. The re-analysis of previous measurements with the MASS is performed to test the applicability of this approach in real data processing. It is shown that most of the actual measurements satisfy the criteria of short exposures. Results: The expressions for the mean wind speeds bar V_2 in the free atmosphere from the measurement of the scintillation indices are derived for this regime. These values provide an estimate of the atmospheric coherence time ?0 without the need of empirical calibration. The verification of the method based on real measurements of the resulting ?0 agree well with independent methods.

Kornilov, V.



Phase contrast imaging with conventional x-ray sources at acceptable dose levels and exposure times  

NASA Astrophysics Data System (ADS)

X-ray Phase Contrast imaging (XPCi) generates image contrast from interference and refraction effects (instead of x-ray attenuation), which leads to enhanced visibility of all details and to the detection of features classically considered ``x-ray invisible.'' XPCi thus has great potential in a wide range of applications, from the earlier diagnosis of lesions in medical imaging to the detection of faint blemishes in non-destructive testing. However, XPCi seemed to require a high level of (at least spatial) coherence, which restricted its use to synchrotron facilities. Microfocal sources can be used but, due to low emitted flux, result in exposure times too long (hours) for most practical applications. Other attempts were based on aperturing/collimating the focal spot of a conventional source to create sufficient spatial coherence, again limiting the source output and resulting in excessive exposure times and/or delivered dose. This talk will present a method, based on appropriately designed x-ray masks, which works with unapertured and uncollimated conventional sources, at acceptable exposure times and delivered doses. It will describe how the method works, explain how quantitative features can be extracted from the images, and provide examples of application in various fields.

Olivo, Alessandro



Different effects of PM 10 exposure on preterm birth by gestational period estimated from time-dependent survival analyses  

Microsoft Academic Search

Purpose  We conducted this study to determine if the preterm risks due to PM10 exposure vary with the exposure periods during pregnancy. This study was also conducted to estimate the different effects\\u000a of PM10 exposure on preterm birth by exposure periods using the extended Cox model with PM10 exposure as a time-dependent covariate.\\u000a \\u000a \\u000a \\u000a Methods  We studied birth data obtained from the Korea

Young Ju Suh; Ho Kim; Ju Hee Seo; Hyesook Park; Young Ju Kim; Yun Chul Hong; Eun Hee Ha



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

Microsoft Academic Search

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

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



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


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



Demonstration of real-time monitoring of a photolithographic exposure process using chemical ionization mass spectrometry  

SciTech Connect

Silicon wafers are coated with photoresist and exposed to ultraviolet (UV) light in a laboratory to simulate typical conditions expected in an actual semiconductor manufacturing process tool. Air is drawn through the exposure chamber and analyzed using chemical ionization mass spectrometry (CI/MS). Species that evaporate or outgas from the wafer are thus detected. The purpose of such analyses is to determine the potential of CI/MS as a real-time process monitoring tool. Results demonstrate that CI/MS can remotely detect the products evolved before, during, and after wafer UV exposure; and that the quantity and type of products vary with the photoresist coated on the wafer. Such monitoring could provide semiconductor manufacturers benefits in quality control and process analysis. Tool and photoresist manufacturers could also realize benefits from this measurement technique with respect to new tool, method, or photoresist development. The benefits realized can lead to improved device yields and reduced product and development costs.

Mowry, C.D. [Sandia National Labs., Albuquerque, NM (United States). Analytical Chemistry Dept.



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

PubMed Central

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 of birth control. Toxicological effects on spermatogenesis in humans and animals have been described after exposure to several pesticides. The aim of this study was to examine time to pregnancy among farmers who used pesticides (traditional farmers) and farmers who did not (organic farmers). METHODS: A total of 904 (84%) men, selected from the Danish Ministry of Agriculture lists of traditional and organic farmers, participated in telephone interviews. Information was collected on time to pregnancy for the youngest child, exposure to pesticides, and potential confounders. RESULTS: With the discrete analogue of the Cox regression model (including potential confounders: male and female smoking, female age, parity, and contraceptive method), the fecundability ratio between traditional farmers who used pesticides and organic farmers was 1.03 (95% confidence interval (95% CI) 0.75 to 1.40). In the group of farmers who sprayed with pesticides, none of the characteristics related to the use of pesticides could account for the variation in time to pregnancy. CONCLUSIONS: No overall effect of pesticides on male fecundability was found in this retrospective study among Danish farmers. Also, we found no evidence of higher male fecundability in organic farmers.  

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



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


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



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



Irradiation Records, Cosmic-Ray Exposure Ages, and Transfer Times of Meteorites  

NASA Astrophysics Data System (ADS)

During the 4.56-G.y. history of the solar system, every meteorite experienced at least one exposure to cosmic rays as a meter-sized meteoroid. The cosmic-ray exposure (CRE) age of a meteorite measures the integral time of exposure to galactic cosmic rays (GCRs). A fraction of meteoritic material was also irradiated by cosmic rays before ejection from kilometer-sized parent bodies (preirradiation); studies of preirradiation effects yield information about surface processes on planetary objects. In this review we discuss some methods of calculation for CRE ages of meteorites and present CRE age histograms for asteroidal, martian, and lunar meteorites. Compositional, formation-age, and CRE records indicate that probably the ~18,000 meteorites in our collections come from about 100 different asteroids. Stone meteorites exhibit CRE ages ?120 m.y., while those of iron meteorites are generally, but not always, longer (up to 1500 m.y.); these CRE ages also show evidence for long-term GCR flux variations in the solar neighborhood. The CRE age differences of the various classes either signal different source regions, variability in the size of the Yarkovsky effect, or different resistance against crushing. Rocks blasted off the Moon and Mars by asteroidal or cometary impacts represent surface areas unlikely to be sampled by manned or automated missions; their CRE ages indicate that they come from some eight different sites on the Moon and also on Mars.

Eugster, O.; Herzog, G. F.; Marti, K.; Caffee, M. W.


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.



Exploratory study on a statistical method to analyse time resolved data obtained during nanomaterial exposure measurements  

NASA Astrophysics Data System (ADS)

Most of the measurement strategies that are suggested at the international level to assess workplace exposure to nanomaterials rely on devices measuring, in real time, airborne particles concentrations (according different metrics). Since none of the instruments to measure aerosols can distinguish a particle of interest to the background aerosol, the statistical analysis of time resolved data requires special attention. So far, very few approaches have been used for statistical analysis in the literature. This ranges from simple qualitative analysis of graphs to the implementation of more complex statistical models. To date, there is still no consensus on a particular approach and the current period is always looking for an appropriate and robust method. In this context, this exploratory study investigates a statistical method to analyse time resolved data based on a Bayesian probabilistic approach. To investigate and illustrate the use of the this statistical method, particle number concentration data from a workplace study that investigated the potential for exposure via inhalation from cleanout operations by sandpapering of a reactor producing nanocomposite thin films have been used. In this workplace study, the background issue has been addressed through the near-field and far-field approaches and several size integrated and time resolved devices have been used. The analysis of the results presented here focuses only on data obtained with two handheld condensation particle counters. While one was measuring at the source of the released particles, the other one was measuring in parallel far-field. The Bayesian probabilistic approach allows a probabilistic modelling of data series, and the observed task is modelled in the form of probability distributions. The probability distributions issuing from time resolved data obtained at the source can be compared with the probability distributions issuing from the time resolved data obtained far-field, leading in a quantitative estimation of the airborne particles released at the source when the task is performed. Beyond obtained results, this exploratory study indicates that the analysis of the results requires specific experience in statistics.

Clerc, F.; Njiki-Menga, G.-H.; Witschger, O.



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


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



Long term compulsivity on the 5-choice serial reaction time task after acute Chlorpyrifos exposure.  


Pesticide exposure has been associated with neuropsychological and psychiatric impairments and neurodegenerative disorders. Pesticide exposure commonly causes a deficit in inhibitory control behaviours. In the present study, we investigated whether acute exposure to organophosphate (OP) chlorpyrifos (CPF) is related to long-term lack of inhibitory control; we also examined the possible neurochemical basis of this association. Lister Hooded rats were exposed to an acute dose of CPF (250 mg/kg). Seven months later, we tested inhibitory control with the 5-choice serial reaction time task (5-CSRTT). We manipulated the baseline conditions of this task and also systemically pre-administered d-amphetamine, quinpirole, dizocilpine (MK-801) or ketanserin. We also analysed the post-mortem baseline levels of monoamines and amino acids in different brain regions. On the 5-CSRT task, CPF-exposed rats showed elevated perseverative responses that persisted across manipulation of baseline conditions of the task and under most of the pharmacological challenges tested. Only D-amphetamine induced a dose-dependent amelioration of the increased perseverative responses in the CPF group. The CPF group also exhibited increased levels of dopamine metabolism in the hippocampus and decreased levels of gamma-aminobutyric acid (GABA) and glutamate in the striatum compared to the vehicle group. These findings suggest that CPF induced a long-term compulsivity that was apparent in the 5-CSRT task and associated with changes in monoaminergic and amino acid brain systems of inhibitory control function. Exposure to high doses of OP should be taken into account in studies of environmental causes for neurodegenerative, neuropsychological and neuropsychiatric disorders. PMID:23194828

Montes de Oca, Lara; Moreno, Margarita; Cardona, Diana; Campa, Leticia; Suñol, Cristina; Galofré, Mireia; Flores, Pilar; Sánchez-Santed, Fernando



Estimation of exposure time to GSM900 radiation causing auditory brainstem response changes in rabbits using neuro-fuzzy system  

Microsoft Academic Search

The wide and growing usage of cellular phones has raised questions about the possible health risks associated with radio frequency (RF) electromagnetic fields. Since it is very difficult to accurately measure and quantify the RF exposure level for all individuals, it would be helpful for epidemiologists and cellular phone users to obtain a time estimate of specific radiation exposure generating

T. N. Kapetanakis; A. Kaprana; I. O. Vardiambasis; M. P. Ioannidou



Validation study of the Short Time Exposure (STE) test to assess the eye irritation potential of chemicals  

Microsoft Academic Search

Short Time Exposure (STE) test is a cytotoxicity test in SIRC cells (rabbit corneal cell line) that assesses eye irritation potential following a 5-min chemical exposure. This validation study assessed transferability, intra- and inter-laboratory reproducibility, and predictive capacity of STE test in five laboratories (supported by Japanese Society for Alternatives to Animal Experiments). Sodium lauryl sulfate, calcium thioglycolate, and Tween

Hitoshi Sakaguchi; Naoko Ota; Takashi Omori; Hirofumi Kuwahara; Takashi Sozu; Yumi Takagi; Yutaka Takahashi; Kouko Tanigawa; Miki Nakanishi; Tsuneaki Nakamura; Takashi Morimoto; Shinobu Wakuri; Yuko Okamoto; Mayumi Sakaguchi; Takumi Hayashi; Takayuki Hanji; Shinichi Watanabe




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...


Dose, exposure time, and resolution in Serial X-ray Crystallography  

SciTech Connect

Using detailed simulation and analytical models, the exposure time is estimated for serial crystallography, where hydrated laser-aligned proteins are sprayed across a continuous synchrotron beam. 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 fluxes of molecules and X-rays. Orientation of the diffracting molecules is achieved by laser alignment. We evaluate the incident X-ray fluence (energy/area) required to obtain a given resolution from (1) an analytical model, giving the count rate at the maximum scattering angle for a model protein, (2) explicit simulation of diffraction patterns for a GroEL-GroES protein complex, and (3) the frequency cut off of the transfer function following iterative solution of the phase problem, and reconstruction of a density map in the projection approximation. These calculations include counting shot noise and multiple starts of the phasing algorithm. The results indicate the number of proteins needed within the beam at any instant for a given resolution and X-ray flux. We confirm an inverse fourth power dependence of exposure time on resolution, with important implications for all coherent X-ray imaging. We find 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 {angstrom} should be possible with short (below 100 s) exposures.

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



Application of alternative spatiotemporal metrics of ambient air pollution exposure in a time-series epidemiological study in Atlanta.  


Exposure error in studies of ambient air pollution and health that use city-wide measures of exposure may be substantial for pollutants that exhibit spatiotemporal variability. Alternative spatiotemporal metrics of exposure for traffic-related and regional pollutants were applied in a time-series study of ambient air pollution and cardiorespiratory emergency department visits in Atlanta, GA, USA. Exposure metrics included daily central site monitoring for particles and gases; daily spatially refined ambient concentrations obtained from regional background monitors, local-scale dispersion, and hybrid air quality models; and spatially refined ambient exposures from population exposure models. Health risk estimates from Poisson models using the different exposure metrics were compared. We observed stronger associations, particularly for traffic-related pollutants, when using spatially refined ambient concentrations compared with a conventional central site exposure assignment approach. For some relationships, estimates of spatially refined ambient population exposures showed slightly stronger associations than corresponding spatially refined ambient concentrations. Using spatially refined pollutant metrics, we identified socioeconomic disparities in concentration-response functions that were not observed when using central site data. In some cases, spatially refined pollutant metrics identified associations with health that were not observed using measurements from the central site. Complexity and challenges in incorporating modeled pollutant estimates in time-series studies are discussed. PMID:23963512

Sarnat, Stefanie Ebelt; Sarnat, Jeremy A; Mulholland, James; Isakov, Vlad; Ozkaynak, Halûk; Chang, Howard H; Klein, Mitchel; Tolbert, Paige E



Self-Tuning Laser Speckle Contrast Analysis Based on Multiple Exposure Times with Enhanced Temporal Resolution  

NASA Astrophysics Data System (ADS)

Laser Speckle Contrast Analysis (LASCA) was introduced in 1981. Since then, several enhancements were applied to it. Nowadays, thetechnique can provide relatively high accuracy as well as high temporal and spatial resolution during the examination of ocular or cerebraltissues. However, in the case of skin, the results are highly affected by the intensive scattering on the skin surface, as the scattering onthe non-moving parts of the sample lead to the detrimental decrease of the accuracy. We present a LASCA method based on the use ofmultiple exposure times, combined with the switching-mode control of the light intensity and a special sampling technique to achieve nearto real-time measurement of the skin perfusion. The system based on our method is able to automatically handle the destructive effect ofthe skin surface and re-tune itself according to the changes of the sample, while it provides full-field perfusion maps with high accuracy,without the need of any precalibrations.

Zölei, D.; Smausz, T.; Hopp, B.; Bari, F.



Change of Exposure Response over Time and Long-Term Risk of Silicosis among a Cohort of Chinese Pottery Workers  

PubMed Central

An analysis was conducted on a cohort of Chinese pottery workers to estimate the exposure-response relationship between respirable crystalline silica dust exposure and the incidence of radiographically diagnosed silicosis, and to estimate the long-term risk of developing silicosis until the age of 65. The cohort comprised 3,250 employees with a median follow-up duration of around 37 years. Incident cases of silicosis were identified via silicosis registries (Chinese X-ray stage I, similar to International Labor Organisation classification scheme profusion category 1/1). Individual exposure to respirable crystalline silica dust was estimated based on over 100,000 historical dust measurements. The association between dust exposure, incidence and long-time risk of silicosis was quantified by Poisson regression analysis adjusted for age and smoking. The risk of silicosis depended not only on the cumulative respirable crystalline silica dust exposures, but also on the time-dependent respirable crystalline silica dust exposure pattern (long-term average concentration, highest annual concentration ever experienced and time since first exposure). A long-term “excess” risk of silicosis of approximately 1.5/1,000 was estimated among workers with all annual respirable crystalline silica dust concentration estimates less than 0.1 mg/m3, using the German measurement strategy. This study indicates the importance of proper consideration of exposure information in risk quantification in epidemiological studies.

Sun, Yi; Bochmann, Frank; Morfeld, Peter; Ulm, Kurt; Liu, Yuewei; Wang, Heijiao; Yang, Lei; Chen, Weihong



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.



Changes in soft tissue concentrations of plutonium and americium with time after human occupational exposure  

SciTech Connect

Concentrations of {sup 239+240}Pu and {sup 241}Am in human soft tissues (testes, thyroid gland, kidneys, spleen, heart, skeletal muscle, brain, and pancreas) were compared to those in the livers of the same subject. The subjects were volunteer donors with occupational exposures to plutonium and americium autopsied as part of the United States Transuranium and Uranium Registries program. The temporal distributions of tissue-to-liver ratios were compared to liver uptake fractions assumed on the basis of current models to estimate the initial uptake fractions for each tissue studied. Regressions of the ratios were used to compare tissue retention half-times of those of the liver. Effective half-times for plutonium and americium in the tissues studied were similiar to those for the liver with three exceptions: (1) the clearance half-time for plutonium in kidneys is shorter that that of liver; (2) the retention half-time for plutonium is testes is longer that that of liver; and (3) the retention half-time for americium in skeletal muscle was longer than in the liver. Next to liver, the greatest initial uptake of systemic actinides was in skeletal muscle and the greatest initial concentrations were in the spleen. The uptake fraction of plutonium in the testes proposed by the ICRP was verified. 20 refs., 2 figs., 5 tabs.

Filipy, R.E.; Kathren, R.L. [Washington State Univ., Richland, VA (United States)




EPA Science Inventory

Because of fluctuations in levels of industrial air pollution linked to weather and other factors, a joint U.S.-Soviet research team studied differences in the effect of time in exposures of air-breathing animals to controlled varied concentrations of air pollutants. An experimen...


Real-Time RF Exposure Setup Based on a Multiple Electrode Array (MEA) for Electrophysiological Recording of Neuronal Networks  

Microsoft Academic Search

Real-time investigations on the effects of mo- bile-phone exposure on neuronal activity are considered the highest priority in the health risk assessment of RF fields. There- fore, this paper describes a new real-time exposure setup for electrophysiology recordings, combining an open transverse electro-magnetic cell with a multiple electrode array. The system was numerically and experimentally characterized at a frequency of

Caterina Merla; Nicolas Ticaud; Delia Arnaud-Cormos; Bernard Veyret; Philippe Leveque



[Characteristics of the design of power supply devices for radiodiagnostic apparatus].  


Basic features specific for the X-ray power supply facilities feeding modern roentgenological units, which became necessary after the introduction of automatic exposure, decreasing-load conditions and X-ray image intensification relays. Classification of the feeding devices, depending upon the purpose of the apparatus is presented and recommendations for the adoption of suitable patterns for the main circuitry of the apparatus and methods of its calculation are given. PMID:1152655

Blinov, N N


Changes in organic matter mineral interactions for marine sediments with varying oxygen exposure times  

NASA Astrophysics Data System (ADS)

Density fractionation, X-ray photoelectron spectroscopy (XPS) and amino acid analyses were used to evaluate the physical form of preserved organic carbon (OC) in sediments from transects in the north east Pacific Ocean off the Mexican (Mazatlan) and Washington coasts. Low density (i.e. mineral-free) organic material dominated the OC in sediments with very short oxygen exposure times (OET <1 yr; total wt% OC 7.9-9.3, ˜70% in ? < 1.9 fractions). Quantities of low density OC decreased with increasing OET, suggesting that organic-rich debris was oxygen-sensitive. As OET increased from years to decades, OC was found predominately in the form of organic-mineral aggregates (58-77% of total OC was in the 1.9-2.2 ? mesodensity fraction). Aggregated OC then decreased in abundance as a function of OET, suggesting that long-term oxygen exposure leads to destruction of organic-mineral aggregates. At OET values of centuries to millennia, the dominant forms of organic matter were OC sorbed to mineral surfaces (˜50% of total) and OC locked within biogenic diatom frustules (˜22% of total). These two physical forms of OC in marine sediments may provide the best long-term protection for OC.

Arnarson, Thorarinn S.; Keil, Richard G.



Prior exposure to hypoxic-induced apnea impairs protective responses of newborn rats in an exposure-dependent fashion: influence of normoxic recovery time  

Microsoft Academic Search

ABSTRACT Experiments,were,carried out to determineif prior exposure,to hypoxic-induced apnea impairs protective responses of newborn rats. Ninety-five, 5 to 6 day-old rat pups were instrumented,for respiratory measurements and ,placed ,prone ,in a ,metabolic ,chamber regulated,to 37.0,C. The time to first and ,last gasp as ,well as the ,number ,of gasps were,determined,upon,exposure,to unrelenting hypoxia,after each pup had experienced 0,1, 2, 3, 4,

James E. Fewell; Vienna K. Y. Ng; Chunfen Zhang



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


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




Microsoft Academic Search

Aim of present study was to investigate whether radio frequency electromagnetic field (RF-EMF) exposure induces reversible effects on brain microcirculation observable only during exposure. Using our developed ''8''-shaped loop

H. Masuda; A. Ushiyama; S. Hirota; S. Watanabe; Y. Yamanaka; C. Ohkubo


Do time in child care and peer group exposure predict poor socioemotional adjustment in Norway?  


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 emerge in Norway, a country with a different child-care system. The children's externalizing problems and social competence were unrelated to their child-care experience. More time spent in child care during the first 4.5 years of life and experiencing peer groups of < 16 or > 18 children predicted greater caregiver-child conflict. The effect sizes were small. The results are discussed in terms of cross-national child-care differences. PMID:23461755

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



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



Gold nanoparticles cellular toxicity and recovery: effect of size, concentration and exposure time.  


Gold nanoparticles (AuNPs) are used in many applications; however, their interactions with cells and potential health risk(s) are not fully known. In this manuscript, we describe the interactions of AuNPs with human dermal fibroblasts and show that they can penetrate the plasma membrane and accumulate in large vacuoles. We also demonstrate that the uptake of the AuNPs is a function of time, their size and concentration. Specifically, we demonstrate that 45 nm AuNPs penetrate cells via clathrin-mediated endocytosis, while the smaller 13 nm enter mostly via phagocytosis. Furthermore, we provide evidence of cytoskeleton filament disruption as a result of AuNPs exposure and reconstitution during recovery (following AuNP removal), despite no changes in actin or beta-tubulin protein levels. In contrast, the expression of the extracellular matrix (ECM) proteins, collagen and fibronectin, was diminished in the cells exposed to AuNPs. We also examined the proliferation rates of cells exposed to AuNPs and show that its diminution is a function of apoptosis and speculate that apoptosis results from the number of vacuoles present in the cells, which is probably the main factor that disrupts the cytoskeleton causing cell area contraction and decreases in motility. Lastly, we also present data that indicates that AuNPs' damage to cells is not permanent and that the cells can completely recover as a function of AuNPs' size, concentration and exposure time. Taken together, our data suggest that AuNPs exert detrimental effects on cell function that could reverse following AuNPs removal. PMID:20795906

Mironava, Tatsiana; Hadjiargyrou, Michael; Simon, Marcia; Jurukovski, Vladimir; Rafailovich, Miriam H



Bayesian estimation of hourly exposure functions by crash type and time of day.  


The study describes an investigation of the relationship between crash occurrence and hourly volume counts for small samples of highway segments from two states: Michigan and Connecticut. We used a hierarchical Bayesian framework to fit binary regression models for predicting crash occurrence for each of four crash types: (1) single-vehicle, (2) multi-vehicle same direction, (3) multi-vehicle opposite direction, and (4) multi-vehicle intersecting direction, as a function of the hourly volume, segment length, speed limit and pavement width. The results reveal how the relationship between crashes and hourly volume varies by time of day, thus improving the accuracy of crash occurrence predictions. The results show that even accounting for time of day, the disaggregate exposure measure - hourly volume - is indeed non-linear for each of the four crash types. This implies that at any time of day, the crash occurrence is not proportional to the hourly volume. These findings help us to further understand the relationship between crash occurrence and hourly volume, segment length and other risk factors, and facilitate more meaningful comparisons of the safety record of seemingly similar highway locations. PMID:16782038

Qin, Xiao; Ivan, John N; Ravishanker, Nalini; Liu, Junfeng; Tepas, Donald



Association of Established Smoking Among Adolescents With Timing of Exposure to Smoking Depicted in Movies  

PubMed Central

Background It is not known whether exposure to smoking depicted in movies carries greater influence during early or late adolescence. We aimed to quantify the independent relative contribution to established smoking of exposure to smoking depicted in movies during both early and late adolescence. Methods We prospectively assessed 2049 nonsmoking students recruited from 14 randomly selected public schools in New Hampshire and Vermont. At baseline enrollment, students aged 10–14 years completed a written survey to determine personal, family, and sociodemographic characteristics and exposure to depictions of smoking in the movies (early exposure). Seven years later, we conducted follow-up telephone interviews to ascertain follow-up exposure to movie smoking (late exposure) and smoking behavior. We used multiple regression models to assess associations between early and late exposure and development of established smoking. Results One-sixth (17.3%) of the sample progressed to established smoking. In analyses that controlled for covariates and included early and late exposure in the same model, we found that students in the highest quartile for early exposure had 73% greater risk of established smoking than those in the lowest quartile for early exposure (27.8% vs 8.6%; relative risk for Q4 vs Q1 = 1.73, 95% confidence interval = 1.14 to 2.62). However, late exposure to depictions of smoking in movies was not statistically significantly associated with established smoking (22.1% vs 14.0%; relative risk for Q4 vs Q1 = 1.13, 95% confidence interval = 0.89 to 1.44). Whereas 31.6% of established smoking was attributable to early exposure, only an additional 5.3% was attributable to late exposure. Conclusions Early exposure to smoking depicted in movies is associated with established smoking among adolescents. Educational and policy-related interventions should focus on minimizing early exposure to smoking depicted in movies.

Longacre, Meghan R.; Beach, Michael L.; Adachi-Mejia, Anna M.; Titus, Linda J.; Dalton, Madeline A.



Role of time as a factor in the toxicity of chemical compounds in intermittent and continuous exposures. part I. effects of continuous exposure  

Microsoft Academic Search

Because of fluctuations in levels of industrial air pollution linked to weather and other factors, a joint U.S.?Soviet research team studied differences in the effect of time in exposures of air?breathing animals to controlled varied concentrations of air pollutants. An experimental model environment was used to investigate the effects of nitrogen dioxide (NO2), sulfur dioxide (SO2), and benzene (C6H6) in

D. E. Gardner; D. L. Coffin; M. A. Pinigin; G. I. Sidorenko



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.



Monitoring of 1-min personal particulate matter exposures in relation to voice-recorded time-activity data.  


Recent studies on the association between exposures to airborne particulate matter (PM) and disease have identified short-term peaks in PM exposures as posing especial health threats. Lightweight personal instruments are needed to characterize short-term exposures to PM and to identify the most important sources of high PM excursions. In this study, we measured exposure to fine PM using a small personal nephelometer (pDR; MIE, Inc) to investigate the utility of this instrument in identifying activities and microenvironments most associated with high PM exposures and the magnitude and duration of peaks in PM exposures. Ten adult volunteers wore a pDR recording PM concentrations at 1-min time intervals for 1 week each. PM concentrations were measured by the pDR in units of microg/m(3) based on light scatter. The use of a time-stamped voice recorder enabled activity and location to be continuously documented in real time. In addition, a small, inexpensive light intensity logger was affixed to the pDR to evaluate the potential of this instrument to assist in verifying wearer- recorded data. For each person, patterns of PM exposure were remarkably consistent over daily activities and showed large excursions associated with specific indoor and outdoor microenvironments and activities, such as cooking. When the magnitude and duration of excursions in PM were analyzed, we found that high PM levels occurred in relatively few of the minutes measured but comprised a substantial fraction of the total exposure to PM. Fifteen-minute averaged PM levels were found to be as much as 10 times the daily average. When the data were analyzed with a generalized estimating equation model to account for effects of autocorrelation and clustering, PM exposure was significantly higher during subject-reported events including barbeque, yard work, being near pets or construction activities, cooking, and environmental tobacco smoke exposure, as compared with periods with no pollution events. When light intensity data were explored to determine whether these loggers could be of potential use in establishing or verifying indoor vs outdoor location for future PM studies, we found that personal light intensity measurements differed among indoor, outdoor, and in-car environments (P<0.001). Overlap between measured values implies that light intensity cannot be used to absolutely predict location; however, a sudden increase or decrease in light intensity was highly associated with participant report of location change between indoors and outdoors. This study demonstrates the utility of the pDR in identifying patterns of personal exposures to particulate matter and especially in registering the magnitude and duration of excursions in PM in relation to location and activity. PMID:11771933

Quintana, P J; Valenzia, J R; Delfino, R J; Liu, L J



Effect of heat exposure on thermoregulation and hockey-specific response time in field hockey goalkeepers.  


This study examined the thermoregulatory responses in field hockey goalkeepers during games (Part A), and assessed the effect of heat stress on hockey-specific response time (Part B). In Part A, core temperature (T(c)), skin temperature (T(sk)), body mass, fluid consumption and heart rate (HR) responses of six goalkeepers during two premier level club games in the Western Australian (winter) hockey season were recorded. Part B assessed the same measures, plus a response time test on four goalkeepers playing a simulated game inside a climate chamber in cool (COOL: 20 degrees C, 40% RH) and hot (HOT: 35 degrees C, 40% RH) conditions. In Part A, the mean (+/-SD) T(c) and T(sk) measured in games was 38.49+/-0.20 degrees C and 34.99+/-0.99 degrees C, with increases from baseline of 1.34+/-0.19 degrees C and 1.08+/-0.30 degrees C, respectively. Most of the increase in T(c) resulted from the pre-game warm-up. In Part B, T(c) and T(sk) only increased significantly (p<0.05) from baseline in the HOT condition (0.62+/-0.18 degrees C and 1.61+/-0.82 degrees C, respectively). Response time was significantly slower (0.87+/-0.14s, p<0.01) after heat exposure, compared to COOL (0.75+/-0.15s), but the number of correct responses was not affected. For optimal performance, careful attention should be given to strategies to limit T(c) increases in field hockey goalkeepers during matches. PMID:19574100

Malan, Marcelle; Dawson, Brian; Goodman, Carmel; Peeling, Peter



Effects of time-varying exposures adjusting for time-varying confounders: the case of alcohol consumption and risk of incident human immunodeficiency virus infection  

Microsoft Academic Search

Objective  Discuss issues related to time-varying exposures using as an example the recently meta-analyzed literature (Baliunas et al.\\u000a in Int J Public Health, 2009) on alcohol consumption and risk of HIV infection.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Cataloged sources of bias and imprecision in the context of time-varying exposures.\\u000a \\u000a \\u000a \\u000a Results  Confounding, selection, or measurement bias may occur when standard regression approaches are used to estimate effects of

Chanelle J. Howe; Petra M. Sander; Michael W. Plankey; Stephen R. Cole



Time-patterns of antibiotic exposure in poultry production--a Markov chains exploratory study of nature and consequences.  


This article describes the use of Markov chains to explore the time-patterns of antimicrobial exposure in broiler poultry. The transition in antimicrobial exposure status (exposed/not exposed to an antimicrobial, with a distinction between exposures to the different antimicrobial classes) in extensive data collected in broiler chicken flocks from November 2003 onwards, was investigated. All Markov chains were first-order chains. Mortality rate, geographical location and slaughter semester were sources of heterogeneity between transition matrices. Transitions towards a 'no antimicrobial' exposure state were highly predominant, whatever the initial state. From a 'no antimicrobial' exposure state, the transition to beta-lactams was predominant among transitions to an antimicrobial exposure state. Transitions between antimicrobial classes were rare and variable. Switches between antimicrobial classes and repeats of a particular class were both observed. Application of Markov chains analysis to the database of the nation-wide antimicrobial resistance monitoring programme pointed out that transition probabilities between antimicrobial exposure states increased with the number of resistances in Escherichia coli strains. PMID:17386950

Chauvin, C; Clement, C; Bruneau, M; Pommeret, D



Task and Time-Dependent Weighting Factors in a Retrospective Exposure Assessment of Chemical Laboratory Workers  

Microsoft Academic Search

A chemical exposure assessment was conducted for a cohort mortality study of 6157 chemical laboratory workers employed between 1943 and 1998 at four Department of Energy sites in Oak Ridge, Tennessee, and Aiken, South Carolina. Previous studies of chemical laboratory workers have included members within professional societies where exposure assessment was either limited or not feasible, or chemical processing employees

Scott A. Henn; David F. Utterback; Kathleen M. Waters; Andrea M. Markey; William G. Tankersley



Performance of a 512 x 512 Gated CMOS Imager with a 250 ps Exposure Time  

SciTech Connect

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, A T; Moody, J D; Hsing, W W; Brown, C G; Griffin, M; Mead, A S



Exposure time to hepatitis B virus and associated risk factors among children in Edirne, Turkey.  


Hepatitis B virus (HBV) infection is endemic in Turkey, but the main routes of transmission were not well established. This study aims to detect the exposure time to HBV and associated risk factors among children. In a sampling group of children aged 0-19 years living in Edirne, antiHBc, antiHBs and HBsAg were screened by the microELISA method. A questionnaire was also completed for each child. In 717 children that were included in the study, the total antiHBc seropositivity was 5.4% and was 1.8, 0.8, 1.7, 6.8, 11.8% in 0-1, 2-5, 6-10, 11-14, 15-19 years age groups respectively. The overall HBsAg seropositivity was 1.7%. The risk of HBV infection increased after the age of 10 years (OR 7.79, 95% CI 3.01-20.16). Collective circumcision was the only independent factor according to regression analysis. Children living in Edirne should be vaccinated against HBV before reaching 11 years of age. PMID:15962558

Otkun, M; Erdogan, M S; Tatman-Otkun, M; Akata, F



Exposure time to hepatitis B virus and associated risk factors among children in Edirne, Turkey.  

PubMed Central

Hepatitis B virus (HBV) infection is endemic in Turkey, but the main routes of transmission were not well established. This study aims to detect the exposure time to HBV and associated risk factors among children. In a sampling group of children aged 0-19 years living in Edirne, antiHBc, antiHBs and HBsAg were screened by the microELISA method. A questionnaire was also completed for each child. In 717 children that were included in the study, the total antiHBc seropositivity was 5.4% and was 1.8, 0.8, 1.7, 6.8, 11.8% in 0-1, 2-5, 6-10, 11-14, 15-19 years age groups respectively. The overall HBsAg seropositivity was 1.7%. The risk of HBV infection increased after the age of 10 years (OR 7.79, 95% CI 3.01-20.16). Collective circumcision was the only independent factor according to regression analysis. Children living in Edirne should be vaccinated against HBV before reaching 11 years of age.

Otkun, M.; Erdogan, M. S.; Tatman-Otkun, M.; Akata, F.



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


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



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



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



A Cohort study evaluation of maternal PCB exposure related to time to pregnancy in daughters  

PubMed Central

Background Polychlorinated biphenyls (PCBs) remain ubiquitous environmental contaminants. Developmental exposures are suspected to impact reproduction. Analysis of mixtures of PCBs may be problematic as components have a complex correlation structure, and along with limited sample sizes, standard regression strategies are problematic. We compared the results of a novel, empirical method to those based on categorization of PCB compounds by (1) hypothesized biological activity previously proposed and widely applied, and (2) degree of ortho- substitution (mono, di, tri), in a study of the relation of maternal serum PCBs and daughter’s time to pregnancy. Methods We measured PCBs in maternal serum samples collected in the early postpartum in 289 daughters in the Child Health and Development Studies birth cohort. We queried time to pregnancy in these daughters 28–31 years later. We applied a novel weighted quantile sum approach to find the bad-actor compounds in the PCB mixture found in maternal serum. The approach includes empirical estimation of the weights through a bootstrap step which accounts for the variation in the estimated weights. Results Bootstrap analyses indicated the dominant functionality groups associated with longer TTP were the dioxin-like, anti-estrogenic group (average weight, 22%) and PCBs not previously classified by biological activity (54%). In contrast, the unclassified PCBs were not important in the association with shorter TTP, where the anti-estrogenic groups and the PB-inducers group played a more important role (60% and 23%, respectively). The highly chlorinated PCBs (average weight, 89%) were mostly associated with longer TTP; in contrast, the degree of chlorination was less discriminating for shorter TTP. Finally, PCB 56 was associated with the strongest relationship with TTP with a weight of 47%. Conclusions Our empirical approach found some associations previously identified by two classification schemes, but also identified other bad actors. This empirical method can generate hypotheses about mixture effects and mechanisms and overcomes some of the limitations of standard regression techniques.



Optimal combination of number of participants and number of repeated measurements in longitudinal studies with time-varying exposure.  


In the context of observational longitudinal studies, we explored the values of the number of participants and the number of repeated measurements that maximize the power to detect the hypothesized effect, given the total cost of the study. We considered two different models, one that assumes a transient effect of exposure and one that assumes a cumulative effect. Results were derived for a continuous response variable, whose covariance structure was assumed to be damped exponential, and a binary time-varying exposure. Under certain assumptions, we derived simple formulas for the approximate solution to the problem in the particular case in which the response covariance structure is assumed to be compound symmetry. Results showed the importance of the exposure intraclass correlation in determining the optimal combination of the number of participants and the number of repeated measurements, and therefore the optimized power. Thus, incorrectly assuming a time-invariant exposure leads to inefficient designs. We also analyzed the sensitivity of results to dropout, mis-specification of the response correlation structure, allowing a time-varying exposure prevalence and potential confounding impact. We illustrated some of these results in a real study. In addition, we provide software to perform all the calculations required to explore the combination of the number of participants and the number of repeated measurements. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23740818

Barrera-Gómez, Jose; Spiegelman, Donna; Basagaña, Xavier



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



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


Exposure to time varying magnetic fields associated with magnetic resonance imaging reduces fentanyl-induced analgesia in mice  

SciTech Connect

The effects of exposure to clinical magnetic resonance imaging (MRI) on analgesia induced by the mu opiate agonist, fentanyl, was examined in mice. During the dark period, adult male mice were exposed for 23.2 min to the time-varying (0.6 T/sec) magnetic field (TVMF) component of the MRI procedure. Following this exposure, the analgesic potency of fentanyl citrate (0.1 mg/kg) was determined at 5, 10, 15, and 30 min post-injection, using a thermal test stimulus (hot-plate 50 degrees C). Exposure to the magnetic-field gradients attenuated the fentanyl-induced analgesia in a manner comparable to that previously observed with morphine. These results indicate that the time-varying magnetic fields associated with MRI have significant inhibitory effects on the analgesic effects of specific mu-opiate-directed ligands.

Teskey, G.C.; Prato, F.S.; Ossenkopp, K.P.; Kavaliers, M.



Timing of Initial Exposure to Cereal Grains and the Risk of Wheat Allergy  

Microsoft Academic Search

OBJECTIVE.Early exposure to solid foods in infancy has been associated with the development of allergy. The aim of this study was to examine the association between cereal-grain exposures (wheat, barley, rye, oats) in the infant diet and development of wheat allergy. METHODS.A total of 1612 children were enrolled at birth and followed to the mean age of 4.7 years. Questionnaire

Jill A. Poole; Kathy Barriga; Donald Y. M. Leung; Michelle Hoffman; George S. Eisenbarth; Marian Rewers; Jill M. Norris


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

Microsoft Academic Search

This study was designed to determine the ideal manner (schedule and duration) of intravesical chemotherapy using pirarubicin\\u000a (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\\u000a first exposure, at various intervals (3, 6, 12, and 24 h), a second exposure to THP was performed under the same condition

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



Comparison of four mobility particle sizers with different time resolution for stationary exposure measurements  

Microsoft Academic Search

Exposure to airborne ultrafine and nanoparticles has raised increased interest over the recent years as they may cause adverse\\u000a health effects. A common way to quantify exposure to airborne particles is to measure particle number size distributions through\\u000a electrical mobility analysis. Four mobility particle sizers have been subject to a detailed intercomparison study, a TSI Fast\\u000a Mobility Particle Sizer (FMPS),

Christof Asbach; Heinz Kaminski; Heinz Fissan; Christian Monz; Dirk Dahmann; Sonja Mülhopt; Hanns R. Paur; Heinz J. Kiesling; Friedhelm Herrmann; Matthias Voetz; Thomas A. J. Kuhlbusch



Influence of Exposure Time on Gene Expression by Human Intestinal Epithelial Cells Exposed to Lactobacillus acidophilus  

PubMed Central

Analysis of global temporal gene expression by human intestinal cells when exposed to Lactobacillus acidophilus revealed induction of immune-related pathways and NF-?B target genes after a 1-h exposure, compared to a 4- or 8-h exposure. Additionally, an L. acidophilus derivative expressing covalently bound flagellin resulted in increased induction of il8, cxc1, and cxcl2 compared to the parent L. acidophilus.

O'Flaherty, Sarah



BiodosEPR-2006 consensus committee report on biodosimetric methods to evaluate radiation doses at long times after exposure  

Microsoft Academic Search

The requirements for biodosimetric techniques used at long times after exposure, i.e., 6 months to more than 50 years, are unique compared to the requirements for methods used for immediate dose estimation. In addition to the fundamental requirement that the assay measures a physical or biologic change that is proportional to the energy absorbed, the signal must be highly stable

Steven L. Simon; Ian Bailiff; André Bouville; Paola Fattibene; Ruth A. Kleinerman; David C. Lloyd; Stephen W. S. McKeever; Alexander Romanyukha; Alexander V. Sevan’kaev; James D. Tucker; Albrecht Wieser




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, ...


Protease Inhibitor (PIS) Exposure Time And Risk Of Cardiovascular Disease (CVD) In Human Immunodeficiency Virus (HIV) Infected Patients  

Microsoft Academic Search

Background: Some PIs are associated with hyperlipidemia, insulin resistance, hypertension (HTN) and diabetes mellitus (DM), which in turn are risk factors for CVD. Our objective was to quantify the effect of PI exposure time on subsequent CVD events. Methods: The study population was derived from the HIV InsightTM database with data collection from centers funded by the HIV Outpatient Study,

U Iloeje; Y Yuan; G L'Italien; J Mauskopf; S Holmberg; A Moorman; K Wood; R Moore


A Critical Review of Time-Weighted Average as an Index of Exposure and Dose, and of Its Key Elements  

Microsoft Academic Search

Time-weighted average (TWA) is widely used in research and practice, in occupational health, as an index of exposure and dose. Its key element, CT, where C is concentration of contaminant and T is duration of contamination, is recognizable as Haber's rule. Neither TWA nor similar measurements have been scientifically validated, and it does not seem appropriately named. In the late




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.



The microstructural changes and their effect on CCGR after long time thermal exposure in DA718 and STD718  

Microsoft Academic Search

Samples of forged and heat treated DA718 and STD718 were examined to determine the effects of long time thermal exposures at 1200 and 1250°F on microstructures and mechanical properties. In addition to the coalescence of ??\\/?? and the amount increasing of ? phase, the existence of a bcc chromium enriched ?-Cr phase was confirmed by XRD and SEM. The weight

Wang Gailian; Wu Cuiwei; Zhang Maicang; Dong Jianxin; Xie Xishan; John Radavich; Bruce A. Lindsley; Gangshu Shen



Erosion of dentine and enamel in vitro by dietary acids: the effect of temperature, acid character, concentration and exposure time.  


Sales of soft drinks has been increasing by 56% over the last 10 years and are estimated to keep rising at about 2-3% a year. Further, the reported incidence of tooth erosion has been increasingly documented. Whilst these factors could well be linked, many individuals with erosive diets are not presenting with erosion. This would suggest the effects of many variables, hence the aim of these investigations. Methodologies included preparing enamel and dentine samples from unerupted human third molars. Groups of five specimens were placed in citric acid over a temperature range of 5-60 degrees C for 10-min exposures; placed in citric, lactic, malic or phosphoric acid (0.05, 0.1, 0.5, and 1% (w/v)) for 10-min exposures; and placed in the same three organic hydroxy acids at 0.3% (w/v) or phosphoric acid at 0.1% (w/v) for 3 x 10-min exposures. Tissue loss was determined by profilometry. Results showed that increasing temperature, concentration and exposure time increased the erosion of dentine and enamel. This study has shown that under highly controlled conditions, erosion of dentine and enamel by dietary acids can be greatly influenced in vitro by temperature, concentration, type of acid and exposure time. These factors could be employed in order to reduce the erosivity of soft acidic drinks. PMID:11065022

West, N X; Hughes, J A; Addy, M



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



The second phases in Ti40 burn resistant alloy after high temperature exposure for a long time  

Microsoft Academic Search

The Ti40 (Ti–25V–15Cr–0.2Si) alloy is a burn resistant ? titanium alloy. Second phase precipitation after high temperature exposure for a long time has been studied. The second phases, i.e. Ti5Si3 and ?, precipitate from the ? matrix after the Ti40 alloy has been exposed at high temperature for a long time. The Ti5Si3 phase distributes discontinuously along the grain boundary

Y. Q Zhao; H. L Qu; K. Y Zhu; H Wu; C. L Liu; L Zhou



Clutch morphology and the timing of exposure impact the susceptibility of aquatic insect eggs to esfenvalerate.  


We investigated Baetis spp. (mayfly), Hesperoperla pacifica (stonefly), and Brachycentrus americanus (caddisfly) susceptibility at the egg stage to esfenvalerate, a synthetic pyrethroid insecticide. Eggs were obtained from the field or from field-collected gravid females at sites near Corvallis (OR, USA) and the Metolius River at Camp Sherman (OR, USA) for static exposures under controlled conditions for temperature and light. Eggs were exposed to esfenvalerate for 48 h at concentrations ranging from 0.025 to 4.0 microg/L. No effect on mortality or posthatch growth was detected in H. pacifica eggs exposed to esfenvalerate concentrations up to 1.0 microg/L. Exposure to 0.07 microg/L of esfenvalerate, however, caused a significant increase in Baetis spp. egg mortality, and exposure of near-eclosion eggs to lower concentrations (0.025 and 0.05 microg/L) resulted in behavioral effects and reduced survivorship in newly hatched Baetis nymphs. Early stage B. americanus eggs were 10-fold more sensitive to esfenvalerate when removed from the gelatinous clutch before exposure, an indication that the gelatin affords protection from toxicant exposure. Exposures of near-hatch B. americanus clutches to esfenvalerate concentrations ranging between 0.035 and 0.2 microg/L, however, resulted in significant clutch death within clutches resulting from behavioral aberrations of first-instar larvae. The results of the present study suggest that aquatic insect egg clutch morphology can be a strong influence on susceptibility of embryos to esfenvalerate exposure. PMID:18616380

Palmquist, Katherine R; Jenkins, Jeffrey J; Jepson, Paul C



One-time screening to define the problem: Legionella exposure in an electric power company  

SciTech Connect

An electric utility screened 1455 production employees for job exposure to Legionella pneumophila sources, illness history, and antibodies to L pneumophila serotypes I-IV. L pneumophila-associated illness outbreaks had occurred in a neighboring electric utility district; bacteria serocompatible with L pneumophila had been detected in all four plants participating in an environmental survey, and the company was concerned about the implications of these findings for their employees and the public living near power plants with large cooling towers. The survey revealed a prevalence of antibodies in employees consistent with general population surveys. Within the employee group, antibody titer was not associated with either reports of recent illness or work exposure to potential L pneumophila sources. Inability to detect a relationship between exposure to potential L pneumophila sources and specific antibody results was used to define L pneumophila as a historic nonproblem for this company and to rationally advise against the need for an ongoing screening program.

Deubner, D.C.; MacCormack, J.N.; Kleeman, K.; Muhlbaier, L.H.



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.



Coincident timing by nondisabled, mentally retarded, and traumatic brain-injured individuals under varying target-exposure conditions.  


Coincident timing by 15 nondisabled individuals, 15 mentally retarded and 15 traumatically brain injured was measured under varying target-exposure conditions. Absolute constant error, constant error, and variable error were analyzed in separate repeated-measures analyses of variance for early performance (first block of practice), late performance (last block of practice), and retention (last block of retention). Subjects with mental retardation displayed the least accurate and most variable coincident-timing responses. Nondisabled subjects were most influenced by target-exposure time; subjects with traumatic brain injury were most influenced by target-viewing distance; and subjects with mental retardation were most influenced by a combination of target velocity and target-viewing distance. Subjects with mental retardation displayed a too-early response bias, while nondisabled subjects tended to have a too-late response bias. Individuals with traumatic brain injury had a variable response bias. PMID:7675579

Croce, R; Horvat, M; Roswal, G



Relation of concentration and exposure time to the efficacy of niclosamide against larval sea lampreys (Petromyzon marinus)  

USGS Publications Warehouse

The efficacy of 2', 5-dichloro-4'-nitrosalicylanilide (niclosamide) at various concentrations and exposure times was tested against free-swimming larval sea lampreys (Petromyzon marinus) at 72°C and 17°C in Lake Huron water. Concentrations of niclosamide in test solutions ranged from 0.46 to 4.7 mg/L with pH 7.8 to 8.3, total alkalinity 78 to 88 mg/L as CaCO3, and total hardness 95 to 105 mg/L as CaCO3. In each test, six groups of larvae were exposed to a single concentration of niclosamide for times ranging from 30 s to 30 min. Exposure time was treated as the dose and, for each concentration tested, the exposure time necessary to kill 50 and 99.9% of larvae (ET50 and ET99.9) was determined. Linear regressions of the log10-transformed ET50 and ET99.9 on the log10- transformed niclosamide concentrations were significant at both temperatures with r2 ranging from 0.94 to 0.98. The predicted ET50 ranged from 58 sec to 21.7 min and the ET99.9 ranged from 2.5 to 43.5 min across the concentrations and temperatures tested. Niclosamide required a significantly longer time to kill larvae at 12°C than at 17°C.

Scholefield, R. J.; Bergstedt, R. A.; Bills, T. D.



Exposure to Situations Conducive to Delinquent Behavior: The Effects of Time Use, Income, and Transportation  

ERIC Educational Resources Information Center

Multilevel cross-sectional data from the National Longitudinal Study of Adolescent Health were used to test predictions based on Osgood and colleagues' extension of routine activity theory to individual offending. Specifically, the authors examined the associations between delinquent behavior and three variables hypothesized to increase exposure

Anderson, Amy L.; Hughes, Lorine A.




EPA Science Inventory

After exposure for 21 d to sediment spiked with Cd, Pb, Cu, or Zn, oligochaetes held in clean water depurated metal rapidly over the first few hours, but much more slowly from 8 h up to 32 h. Results are consistent with previous work suggresting a 6-h depuration period as general...


Effect of exposure time on the sorption of pesticide emulsifiable concentrates through microporous fabrics  

Microsoft Academic Search

applications and handlers has been a topic of concern for over two decades. Research conducted by Maibach (1971) indicates that dermal sorption could account for up to 87% of the total sorption by the human body. AI though researcher s have proved that use of protective clotbing can reduce dermal exposure, there is stil 1 a need for clothing that

Anugrah Shaw; Kenneth R. Hill



Development and Seed Number in Indeterminate Soybean as Affected by Timing and Duration of Exposure to Long Photoperiods after Flowering  

PubMed Central

Background and Aims Long photoperiods from flowering to maturity have been found to delay reproductive development in soybean (Glycine max) and to increase the number of seeds per unit land area. This study was aimed to evaluate whether sensitivity to photoperiod after flowering (a) is quantitatively related to the length of exposure to long days and (b) persists throughout the whole pod-setting period. It was also evaluated whether seed number was related to changes in the duration of post-flowering phenophases. Methods Two field experiments were conducted with an indeterminate cultivar of soybean of maturity group V. In expt 1, photoperiods 2 h longer than natural daylength were applied during different numbers of days from the beginning pod stage (R3) onwards, while in expt 2 these photoperiod extensions were imposed during 9 consecutive days starting at different times between R3 and R6 (full seed) stages. Key Results There was a quantitative response of development to the number of cycles with a long photoperiod. The exposure to long photoperiods from R3 to R5 (beginning of seed growth) increased the duration of R3–R6 regardless of the timing of exposure. The stages of development comprised in the R3–R6 phase were delayed by current as well as by previous exposure to long days. A positive relationship was found between seed number and the duration of R3–R6, irrespective of the timing and length of exposure to the long photoperiod. Conclusions Sensitivity to photoperiod remained high during the reproductive period and was highly and positively coupled with the processes of generation of yield.

Kantolic, Adriana G.; Slafer, Gustavo A.



Direct and indirect tasks on assessment of dose and time distributions and thresholds of acute radiation exposure.  


Mathematical methods were developed to construct dose and time distributions and their associated risks and threshold values for lethal and non-lethal effects of acute radiation exposure to include mortality and incidence, prodromal vomiting, and agranulocytosis. A new distribution (T-model) was obtained to describe time parameters of acute radiation syndrome such as the latency period, time to onset of vomiting, and time to initiation of agranulocytosis. Based on the dose and time distributions, the parameter translation method was defined using an orthogonal regression, which allows one to solve for these distributions in the case of acute radiation exposure. The assessment of threshold doses was performed for some effects of acute radiation syndrome: for the latency period, ?6-8 Gy absorbed dose and ?0.7-0.9 h time to onset of vomiting; and for incidence (agranulocytosis), ?2-3 Gy absorbed dose and ?2-3 h time to onset of vomiting. The obtained new formula for assessment of radiation risk is applicable to the time parameters of acute radiation syndrome. PMID:22217591

Osovets, S V; Azizova, T V; Day, R D; Wald, N; Moseeva, M B



The significance of the Druckrey-Küpfmüller equation for risk assessment--the toxicity of neonicotinoid insecticides to arthropods is reinforced by exposure time.  


The essence of the Druckrey-Küpfmüller equation dtn = constant (where d = daily dose and t = exposure time-to-effect, with n > 1) for chemical carcinogens is that the total dose required to produce the same effect decreases with decreasing exposure levels, even though the exposure times required to produce the same effect increase with decreasing exposure levels. Druckrey and Küpfmüller inferred that if both receptor binding and the effect are irreversible, exposure time would reinforce the effect. The Druckrey-Küpfmüller equation explains why toxicity may occur after prolonged exposure to very low toxicant levels. Recently, similar dose-response characteristics have been established for the toxicity of the neonicotinoid insecticides imidacloprid and thiacloprid to arthropods. This observation is highly relevant for environmental risk assessment. Traditional approaches that consider toxic effects at fixed exposure times are unable to allow extrapolation from measured endpoints to effects that may occur at other times of exposure. Time-to-effect approaches that provide information on the doses and exposure times needed to produce toxic effects on tested organisms are required for prediction of toxic effects for any combination of concentration and time in the environment. PMID:20803795

Tennekes, Henk A



German health-related environmental monitoring: assessing time trends of the general population's exposure to heavy metals.  


The German system of a health-related environmental monitoring is based upon two instruments: The German Environmental Survey (GerES) and the Environmental Specimen Bank (ESB). The ESB is a tool to describe time trends of human exposure. Each year approx. 500 students from 4 sampling locations are analysed for their heavy metal contents in blood, blood plasma, and urine. GerES is a nationwide representative cross-sectional study that has been conducted four times up to now. Both instruments have been used to measure heavy metals over the last decades and thus provide complementary information. Both instruments are useful to describe time trends. However, combining the two has an added value, which is demonstrated for heavy metals for the first time in this paper. Major results and the changing importance of sources of exposure to heavy metals (Pb, Cd, Hg, Au, Pt, U and Ni) are shown. This leads to the following conclusion about the today's relevance of exposure in Germany. For the study participants of the city of Muenster, lead in whole blood decreased from about 70 ?g/l in 1981 to levels below 15 ?g/l in 2009. GerES data of young adults confirmed this time trend and GerES IV on children revealed the decreasing relevance of lead in outdoor air and in drinking water. The concentrations of mercury in urine decreased because in Germany it is no longer recommended to use amalgam fillings for children. However, GerES IV and ESB data also demonstrate that despite the decline of these heavy metals exposures to nickel and uranium originating from drinking water are still of importance. PMID:23410801

Becker, K; Schroeter-Kermani, C; Seiwert, M; Rüther, M; Conrad, A; Schulz, C; Wilhelm, M; Wittsiepe, J; Günsel, A; Dobler, L; Kolossa-Gehring, M



Microstructural changes during long time service exposure of udimet 500 and nimonic 115  

Microsoft Academic Search

The effects of long term service exposure on the microstructure of Udimet 500 and Nimonic 115 turbine engine components has\\u000a been studied. Sigma (?) phase was detected in both alloys, and its formation could be predicted using critical electron vacancy\\u000a concentrations computed by the revised method of Barrows and Newkirk and the experimental ? phase composition, ?? coarsening\\u000a was quite

A. K. Koul; W. Wallace



Time course of response to ozone exposure in healthy adult females.  


Ozone exposure causes acute decrements in pulmonary function, increases airway responsiveness, and changes the breathing pattern. We examined these responses in 19 ozone-responsive (DeltaFEV(1) > 5%) young females exposed to both air and 0.35 ppm ozone. The randomized 75-min exposures included two 30-min exercise periods at V(E) approximately 40 L/min. Responses were measured before, during, and after exposure and at 18 and 42 h postexposure. FVC, FEV(1), and FIV(0.5) decreased (p <.01) immediately postexposure by 13.2%, 19.9%, and 20.8%, respectively, and the airway responsiveness was significantly increased. Raw increased (p <.05), while TGV remained essentially unchanged. At 18 h postexposure, the airways were still hyperresponsive and FEV(1) and FIV(0.5) were still 5% below the preexposure levels. There were no residual effects in any of the variables at 42 h postexposure. During exercise in ozone the tidal volume was decreased (-14%) and respiratory frequency increased (+15%). The changes in airway responsiveness were not related to changes in spirometric measurements. We found no significant differences between postair and postozone mouth occlusion pressure (Pm(0.1)) and the hypercapnic response to CO(2) rebreathing. We conclude that ozone induced typical acute changes in airway responsiveness and that ventilatory (exercise), spirometric (inspiratory and expiratory), and plethysmographic pulmonary function may show some residual effects for up to 18 h after exposure. The ozone-induced alteration in breathing pattern during exercise does not appear to be related to a change in ventilatory drive. PMID:10715622

Folinsbee, L J; Hazucha, M J



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

Microsoft Academic Search

Ten highly trained endurance athletes were studied to determine the effects of exposure to low ozone (Oâ) 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 Oâ while performing a 1 h competitive simulation protocol on a bicycle ergometer. Endurance




Impact of host exposure time on mass-rearing of Psyttalia concolor (Hymenoptera Braconidae) on Ceratitis capitata (Diptera Tephritidae)  

Microsoft Academic Search

The efficiency of the Psyttalia concolor (Szépligeti) - Ceratitis capitata (Wiedemann) mass-rearing system was investigated. A series of experimental parameters were fixed in order to reproduce in a small-scale, the mass-rearing conditions. Four different parasitization time exposure values were set to study the impacts of these parameters on the parasitization levels and on the para- sitoid fitness. Larvae superparasitized with

Augusto LONI



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

Microsoft Academic Search

Few studies have examined the effects of early life conditions on the timing of the onset of heart disease. We use the remarkable\\u000a example of a representative sample of the population of older Puerto Ricans aged 60– 74 who lived in the countryside during\\u000a childhood (n = 1,438) to examine the effects of seasonal exposures to poor nutrition and infectious

Mary Mceniry; Alberto Palloni



Older adults and visual impairment: what do exposure times and accuracy tell us about performance gains associated with multimodal feedback?  

Microsoft Academic Search

This study examines the effects of multimodal feedback on the performance of older adults with different visual abilities. Older adults possessing normal vision (n=29) and those who have been diagnosed with Age-Related Macular Degeneration (n=30) performed a series of drag-and-drop tasks under varying forms of feedback. User performance was assessed with measures of feedback exposure times and accuracy. Results indicated

Julie A. Jacko; Ingrid U. Scott; Francois Sainfort; Leon Barnard; Paula J. Edwards; V. Kathlene Emery; Thitima Kongnakorn; Kevin P. Moloney; Brynley S. Zorich



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


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. PMID:23509409

Du, Shichuan; Martinez, Aleix M



Real-time measurement of individual occupational radon exposures in tombs of the Valley of the Kings, Egypt.  


The active radon exposure meter developed recently at the German Research Center for Environmental Health (Helmholtz Zentrum München) was used to measure radon concentrations in 12 tombs located in the Valley of the Kings, Egypt. Radon concentrations in air between 50 ± 7 and 12 100 ± 600 Bq m(-3) were obtained. The device was also used to measure individual radon exposures of those persons working as safeguards inside the tombs. For a measurement time of 2-3 d, typical individual radon exposures ranged from 1800 ± 400 to 240 000 ± 13 000 Bq h m(-3), depending on the duration of measurement and radon concentration in the different tombs. Based on current ICRP dose conversion conventions for workers and on equilibrium factors published in the literature for these tombs, individual effective dose rates that range from 1.5 ± 0.3 to 860 ± 50 µSv d(-1) were estimated. If it is assumed that the climatic conditions present at the measurement campaign persist for about half a year, in this area, then effective doses up to ? 66 mSv could be estimated for half a year, for some of the safeguards of tombs where F-values were known. To reduce the exposure of the safeguards, some recommendations are proposed. PMID:21183552

Gruber, E; Salama, E; Rühm, W



Timing and route of exposure affects crystal formation in melamine and cyanuric exposed male and female rats: gavage vs. feeding.  


Effects of the dosing matrix and timing on the onset of renal crystal formation were evaluated in male and non-pregnant female rats (Fisher 344) exposed to both melamine (MEL) and cyanuric acid (CYA) for 28 days. Rats were fed ground feed containing 60 ppm MEL and 60 ppm CYA, (5 mg/kg bw/day equivalent), or exposed via oral gavage to carboxymethylcellulose containing 5 mg/kg bw MEL followed by 5 mg/kg bw CYA either consecutively (<1 min apart) or delayed 45 min after MEL. Staggered gavage exposure to MEL/CYA caused extensive renal crystal formation as compared to when the two compounds were administered consecutively or in feed. Treatment related effects included reduced weight gain, feed consumption, and testicular weight and increased kidney weight, water consumption and urine output. Animals from the staggered MEL/CYA gavage exposure group became ill and were removed after 9 days of exposure. Approximately 1 week after the initiation of exposure microscopic urinalysis revealed MEL/CYA crystals in both groups of gavaged animals but not in the MEL/CYA feed treatment groups. Urinary crystals were smaller (10 ?m) in animals consecutively gavaged. In contrast the urinary crystals were larger (20-40 ?m) and frequently clumped in the animals in the staggered gavage group. PMID:22963836

Sprando, Robert L; Reimschuessel, Renate; Stine, Cynthia B; Black, Thomas; Olejnik, Nicholas; Scott, Michael; Keltner, Zachary; Bandele, Omari; Ferguson, Martine; Nemser, Sarah M; Tkachenko, Andriy; Evans, Eric; Crosby, Tina; Woodling, Kellie; Loukotková, Lucie; da Costa, Gonçalo Gamboa



Effects of time-variable exposure regimes of the insecticide chlorpyrifos on freshwater invertebrate communities in microcosms.  


The present study compared the effects of different time-variable exposure regimes having the same time-weighted average (TWA) concentration of the organophosphate insecticide chlorpyrifos on freshwater invertebrate communities to enable extrapolation of effects across exposure regimes. The experiment was performed in outdoor microcosms by introducing three different regimes: a single application of 0.9?µg active ingredients (a.i.)/L; three applications of 0.3?µg a.i./L, with a time interval of 7?d; and continuous exposure to 0.1?µg a.i./L for 21?d. Measurements showed that the TWA(21d) concentration in the continuous-exposure treatment (0.098?µg/L) was slightly lower than in the three-application (0.116?µg/L) and single-application (0.126?µg/L) treatments. The application of chlorpyrifos resulted in decreased abundances in the arthropod community, with the largest adverse effects reported for the mayfly Cloeon dipterum and cladocerans Daphnia gr. longispina and Alona sp., while smaller effects were observed for other insects, copepods, and amphipods. At the population level, however, the mayfly C. dipterum only responded to the single-application treatment, which could be explained by the toxicokinetics of chlorpyrifos in this species. At the end of the experimental period the invertebrate community showed approximately the same effect magnitude for all treatment regimes. These results suggest that for this combination of concentrations and duration of the TWA, the TWA concentration is more important for most species than the peak concentration for the assessment of long-term risks of chlorpyrifos. PMID:21351295

Zafar, Mazhar Iqbal; Van Wijngaarden, Rene P A; Roessink, Ivo; Van den Brink, Paul J



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



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


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



Risk factors for asthma and timing of exposure among first generation Arab immigrants: a pilot effort to elucidate the role of exposure to risk factors over multiple life stages  

EPA Science Inventory

Considerable controversy exists over the role of aero-allergens in asthma etiology. Some studies show increased risk with microbe and allergen exposure, while others show decreased risk. These discrepancies may be explained by timing of exposure. Previous research suggests that e...


Microstructural changes during long time service exposure of udimet 500 and nimonic 115  

NASA Astrophysics Data System (ADS)

The effects of long term service exposure on the microstructure of Udimet 500 and Nimonic 115 turbine engine components has been studied. Sigma (?) phase was detected in both alloys, and its formation could be predicted using critical electron vacancy concentrations computed by the revised method of Barrows and Newkirk and the experimental ? phase composition, ?' coarsening was quite pronounced in Nimonic 115 turbine blades and varied as a strong function of the temperature distribution along the blade airfoil, ? phase precipitation had no effect on ?' coarsening rates.

Koul, A. K.; Wallace, W.



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


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



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.



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


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



Post-Exposure Sleep Deprivation Facilitates Correctly Timed Interactions Between Glucocorticoid and Adrenergic Systems, which Attenuate Traumatic Stress Responses  

PubMed Central

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.

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



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.



Exposure to peer delinquency as a mediator between self-report pubertal timing and delinquency: A longitudinal study of mediation  

PubMed Central

This study examined exposure to peer delinquency as a mediator between pubertal timing and self-reported delinquency longitudinally and whether this mediational model was moderated by either gender or maltreatment experience. Data were obtained from Time 1, 2, and 3 of a longitudinal study of maltreatment and development. At Time 1 the sample comprised 454 children aged 9–13 years. Analyses via structural equation modeling supported full mediation. Gender did not moderate this mediational relationship, but maltreatment experience did. The results show that early maturing males and females are both at risk for being exposed to peers that may draw them into delinquent behavior. Additionally, the mechanism linking early pubertal timing to delinquency differs depending on maltreatment experience.

Negriff, Sonya; Ji, Juye; Trickett, Penelope K.



Differential gene expression profiling of mouse skin after sulfur mustard exposure: Extended time response and inhibitor effect.  


Sulfur mustard (HD, SM), is a chemical warfare agent that within hours causes extensive blistering at the dermal-epidermal junction of skin. To better understand the progression of SM-induced blistering, gene expression profiling for mouse skin was performed after a single high dose of SM exposure. Punch biopsies of mouse ears were collected at both early and late time periods following SM exposure (previous studies only considered early time periods). The biopsies were examined for pathological disturbances and the samples further assayed for gene expression profiling using the Affymetrix microarray analysis system. Principal component analysis and hierarchical cluster analysis of the differently expressed genes, performed with ArrayTrack showed clear separation of the various groups. Pathway analysis employing the KEGG library and Ingenuity Pathway Analysis (IPA) indicated that cytokine-cytokine receptor interaction, cell adhesion molecules (CAMs), and hematopoietic cell lineage are common pathways affected at different time points. Gene ontology analysis identified the most significantly altered biological processes as the immune response, inflammatory response, and chemotaxis; these findings are consistent with other reported results for shorter time periods. Selected genes were chosen for RT-PCR verification and showed correlations in the general trends for the microarrays. Interleukin 1 beta was checked for biological analysis to confirm the presence of protein correlated to the corresponding microarray data. The impact of a matrix metalloproteinase inhibitor, MMP-2/MMP-9 inhibitor I, against SM exposure was assessed. These results can help in understanding the molecular mechanism of SM-induced blistering, as well as to test the efficacy of different inhibitors. PMID:18955075

Gerecke, Donald R; Chen, Minjun; Isukapalli, Sastry S; Gordon, Marion K; Chang, Yoke-Chen; Tong, Weida; Androulakis, Ioannis P; Georgopoulos, Panos G



Timing of Fetal Exposure to Stress Hormones: Effects on Newborn Physical and Neuromuscular Maturation  

PubMed Central

The purpose of the study was to determine the specific periods during pregnancy in which human fetal exposure to stress hormones affects newborn physical and neuromuscular maturation. Blood was collected from 158 women at 15, 19, 25, and 31 weeks’ gestation. Levels of placental corticotropin-releasing hormone (CRH) and maternal cortisol were determined from plasma. Newborns were evaluated with the New Ballard Maturation Score. Results indicated that increases in maternal cortisol at 15, 19, and 25 weeks and increases in placental CRH at 31 weeks were significantly associated with decreases in infant maturation among males (even after controlling for length of gestation). Results also suggested that increases in maternal cortisol at 31 weeks were associated with increases in infant maturation among females, although these results were not significant after controlling for length of gestation. Findings suggest that stress hormones have effects on human fetal neurodevelopment that are independent of birth outcome.

Schetter, Christine Dunkel; Hobel, Calvin J.; Chicz-DeMet, Aleksandra; Glynn, Laura M.; Sandman, Curt A.



A time to tan: proximal and distal effects of mortality salience on sun exposure intentions.  


According to the dual defense model of terror management, proximal defenses are engaged to reduce the conscious impact of mortality salience, whereas thoughts of death outside of conscious awareness motivate distal defenses aimed at maintaining self-esteem. Two experiments examined these ideas by assessing women's intentions to engage in tanning-related behavior. In Study 1, when concerns about death (relative to dental pain) were in focal attention, participants increased intentions to protect themselves from dangerous sun exposure. In contrast, when thoughts about death were outside of focal attention, participants decreased interest in sun protection. In Study 2, participants primed to associate tanned skin with an attractive appearance responded to mortality concerns outside of focal attention with increased interest in tanning products and services. These findings are discussed in relation to the dual-defense model of terror management, societal determinants of self-esteem, and implications for health risk and promotion. PMID:15466606

Routledge, Clay; Arndt, Jamie; Goldenberg, Jamie L



Ecological impacts of time-variable exposure regimes to the fungicide azoxystrobin on freshwater communities in outdoor microcosms.  


This paper evaluates the effects of different time-varying exposure patterns of the strobilurin fungicide azoxystrobin on freshwater microsocosm communities. These exposure patterns included two treatments with a similar peak but different time-weighted average (TWA) concentrations, and two treatments with similar TWA but different peak concentrations. The experiment was carried out in outdoor microcosms under four different exposure regimes; (1) a continuous application treatment of 10 ?g/L (CAT(10)) for 42 days (2), a continuous application treatment of 33 ?g/L (CAT(33)) for 42 days (3), a single application treatment of 33 ?g/L (SAT(33)) and (4) a four application treatment of 16 ?g/L (FAT(16)), with a time interval of 10 days. Mean measured 42-d TWA concentrations in the different treatments were 9.4 ?g/L (CAT(10)), 32.8 ?g/L (CAT(33)), 14.9 ?g/L (SAT(33)) and 14.7 ?g/L (FAT(16)). Multivariate analyses demonstrated significant changes in zooplankton community structure in all but the CAT(10) treated microcosms relative to that of controls. The largest adverse effects were reported for zooplankton taxa belonging to Copepoda and Cladocera. By the end of the experimental period (day 42 after treatment), community effects were of similar magnitude for the pulsed treatment regimes, although the magnitude of the initial effect was larger in the SAT(33) treatment. This indicates that for long-term effects the TWA is more important for most zooplankton species in the test system than the peak concentration. Azoxystrobin only slightly affected some species of the macroinvertebrate, phytoplankton and macrophyte assemblages. The overall no observed ecologically adverse effect concentrations (NOEAEC) in this study was 10 µg/L. PMID:22278367

Zafar, Mazhar Iqbal; Belgers, J Dick M; Van Wijngaarden, Rene P A; Matser, Arriënne; Van den Brink, Paul J




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...


Effects of Exposure to Part-time Faculty on Community College Transfer  

Microsoft Academic Search

Over the past several decades, one of the most significant changes in the delivery of postsecondary education involves the\\u000a dramatic increase in the use of contingent or part-time faculty. Although the increased use of part-time faculty within higher\\u000a education makes sense from an administrative point of view, its use does not come without criticism. With community colleges\\u000a representing a more

M. Kevin Eagan Jr; Audrey J. Jaeger



Dental Pulp Reaction to Exposure at Different Time Intervals in Open Apex Canine Teeth of Cats  

PubMed Central

INTRODUCTION: Open-apex teeth with irreversible pulpitis require complex and difficult treatment. Providing the right environment for apexogenesis and pulp protection is vital for their long term prognosis. The young pulp of open apex tooth, however, is better equipped against irritation and assault. The aim of this study was to evaluate pulp inflammation in open apex canine teeth of cats. MATERIALS AND METHODS: In this in vivo study, twelve cats with open apex canines were used. Pulps were iatrogenically exposed and the animals were sacrificed at one, seven, thirty and ninety days after pulp exposure. Samples were prepared for histological evaluations. RESULTS: During the first and seventh day, changes were limited to acute inflammation in the coronal pulp. During the first month pulp changes in 45.5% of samples were similar to the seventh day. In the other samples necrosis and abscess spread to the end of the root, and internal resorption and periapical abscess were observed. In 45.5% of samples in the apical region vital tissue was barely observed (during 90 days); in 54.5% of samples however, complete pulp necrosis, internal resorption and a large periapical lesion was observed. CONCLUSION: In one and seven-day periods pulp tissue was vital, however, in the thirty and ninety-day periods, minority of the pulp samples were vital.

Moradi, Saeed; Bidar, Maryam; Zarrabi, Mohammad Hasan; Talati, Ali



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.




EPA Science Inventory

The question What information may be obtained from a time-series regression of health effects on ambient PM concentration?, is of interest to exposure analysts and epidemiologists, especially since exposure analysts find low and frequently non-significant correlations betw...


Microarray Analysis of Gene Expression Patterns in Human Proximal Tubule Cells Over a Short and Long Time Course of Cadmium Exposure  

Microsoft Academic Search

Numerous studies showed that renal proximal tubules cells are the cell type critically affected by chronic exposure to cadmium (Cd). The aim of the present study was to apply global gene expression technology and a human renal epithelial cell culture model (HPT) to determine whether time of exposure to Cd exerts a major influence on the resulting pattern of global

Scott H. Garrett; Seema Somji; Mary Ann Sens; Kurt Zhang; Donald A. Sens



Fluorescence spectrophotometer for the real time detection of cytosolic free calcium from cell suspensions during exposure to extremely low frequency magnetic fields  

Microsoft Academic Search

We have previously observed that cytosolic free calcium ([Ca2+]i) is increased in HL-60 cells after exposure to an extremely low frequency (ELF) magnetic field. To facilitate the investigation of the time dependence of this effect, we built a magnetic field exposure system in which four samples of cells could be kept at constant temperature and maintained in suspension with constant

Jeffrey J. L. Carson; Frank S. Prato



DNA methylation differences after exposure to prenatal famine are common and timing- and sex-specific  

Microsoft Academic Search

Prenatal famine in humans has been associated with various later-life consequences depending on the gestational timing of the insult and the sex of the exposed individual. Epigenetic mechanisms have been proposed to underlie these associations. Indeed, animal studies and our early human data on the imprinted IGF2 locus indicated a link between prenatal nutritional and DNA methylation. However, it remains

Elmar W. Tobi; L. H. Lumey; Rudolf P. Talens; Dennis Kremer; Hein Putter; Aryeh D. Stein; P. E. Slagboom; Bastiaan T. Heijmans



Effect of heat exposure on thermoregulation and hockey-specific response time in field hockey goalkeepers  

Microsoft Academic Search

This study examined the thermoregulatory responses in field hockey goalkeepers during games (Part A), and assessed the effect of heat stress on hockey-specific response time (Part B). In Part A, core temperature (Tc), skin temperature (Tsk), body mass, fluid consumption and heart rate (HR) responses of six goalkeepers during two premier level club games in the Western Australian (winter) hockey

Marcelle Malan; Brian Dawson; Carmel Goodman; Peter Peeling



Timing of brain-derived neurotrophic factor exposure affects life expectancy of new neurons  

Microsoft Academic Search

The high vocal center (HVC) of adult male canaries, Serinus canaria, is necessary for the production of learned song. New neurons are added to HVC every day, where they replace older neurons that have died, but the length of their survival depends on the time of year when they are born. A great number of HVC neurons born in the

Benjamín Alvarez-Borda; Bhagwattie Haripal; Fernando Nottebohm



A Novel Methodology to Evaluate Health Impacts Caused by VOC Exposures Using Real-Time VOC and Holter Monitors  

PubMed Central

While various volatile organic compounds (VOCs) are known to show neurotoxic effects, the detailed mechanisms of the action of VOCs on the autonomic nervous system are not fully understood, partially because objective and quantitative measures to indicate neural abnormalities are still under development. Nevertheless, heart rate variability (HRV) has been recently proposed as an indicative measure of the autonomic effects. In this study, we used HRV as an indicative measure of the autonomic effrects to relate their values to the personal concentrations of VOCs measured by a real-time VOC monitor. The measurements were conducted for 24 hours on seven healthy subjects under usual daily life conditions. The results showed HF powers were significantly decreased for six subjects when the changes of total volatile organic compound (TVOC) concentrations were large, indicating a suppression of parasympathetic nervous activity induced by the exposure to VOCs. The present study indicated these real-time monitoring was useful to characterize the trends of VOC exposures and their effects on autonomic nervous system.

Mizukoshi, Atsushi; Kumagai, Kazukiyo; Yamamoto, Naomichi; Noguchi, Miyuki; Yoshiuchi, Kazuhiro; Kumano, Hiroaki; Yanagisawa, Yukio



Toxicogenomic Studies of the Rat Brain at an Early Time Point Following Acute Sarin Exposure  

Microsoft Academic Search

We have studied sarin-induced global gene expression patterns at an early time point (2 h: 0.5×LD50) using Affymetrix Rat Neurobiology U34 chips and male Sprague–Dawley rats. A total of 46 genes showed statistically significant alterations from control levels. Three gene categories contained more of the altered genes than any other groups: ion channel (8 genes) and calcium channel and binding proteins

Tirupapuliyur V. Damodaran; Stephen T. Greenfield; Anand G. Patel; Holly K. Dressman; Siomon K. Lin; Mohamed B. Abou-Donia




PubMed Central

Metaplasticity, the adaptive changes of long-term potentiation (LTP) and long-term depression (LTD) in response to fluctuations in neural activity is well documented in visual cortex, where dark rearing shifts the frequency threshold for the induction of LTP and LTD. Here we studied metaplasticity affecting spike-timing dependent plasticity (STDP), in which the polarity of plasticity is determined not by the stimulation frequency, but by the temporal relationship between near coincidental pre- and post-synaptic firing. We found that in mouse visual cortex the same regime of deprivation that restricts the frequency range for inducing rate-dependent LTD extends the integration window for inducing timing-dependent LTD, enabling LTD induction with random pre-and postsynaptic firing. Notably the underlying mechanism for the changes in both rate-dependent and time –dependent LTD appears to be an increase of NR2b-containing NMDAR at the synapse. Thus, the rules of metaplasticity might manifest in opposite directions depending on the plasticity induction paradigms.

Guo, Yatu; Huang, Shiyong; de Pasquale, Roberto; McGehrin, Kevin; Lee, Hey-Kyoung; Zhao, Kanxing; Kirkwood, Alfredo




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...


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


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



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



Fos expression in the prefrontal cortex and nucleus accumbens following exposure to retrospective timing tasks.  


The dorsal striatum and prefrontal cortex have been implicated in interval timing. We examined whether performance of temporal discrimination tasks is associated with increased neuronal activation in these areas, as revealed by Fos expression, a marker for neuronal activation. In Experiment 1, rats were trained on a discrete-trials temporal discrimination task in which a light (22 cd/m²) was presented for a variable time, t (2.5-47.5 s), after which levers A and B were presented. A response on lever A was reinforced if t < 25 s, and a response on lever B was reinforced if t > 25 s. A second group was trained on a light-intensity discrimination procedure, in which a light of variable intensity, i (3.6-128.5 cd/m²) was presented for 25 s. A response on lever A was reinforced if i < 22 cd/m², and a response on lever B was reinforced if i > 22 cd/m². In Experiment 2, bisection procedures were used to assess temporal (200-800 ms, 22 cd/m²) and light-intensity (3.6-128.5 cd/m², 400 ms) discrimination. The increase in proportional choice of lever B as a function of stimulus duration or intensity conformed to a two-parameter logistic equation. Fos expression in the prefrontal cortex and nucleus accumbens was higher in rats performing temporal discrimination tasks than in those performing light-intensity discrimination tasks, indicating greater neuronal activation in these areas during temporal discrimination tasks. Fos expression in the dorsal striatum did not differ between rats performing temporal and light-intensity discrimination tasks. These results suggest that the prefrontal cortex and nucleus accumbens are involved in temporal discrimination. PMID:21341886

Valencia Torres, L; Olarte Sánchez, C M; Body, S; Fone, K C F; Bradshaw, C M; Szabadi, E



Time profile of cosmic radiation exposure during the EXPOSE-E mission: the R3DE instrument.  


The aim of this paper is to present the time profile of cosmic radiation exposure obtained by the Radiation Risk Radiometer-Dosimeter during the EXPOSE-E mission in the European Technology Exposure Facility on the International Space Station's Columbus module. Another aim is to make the obtained results available to other EXPOSE-E teams for use in their data analysis. Radiation Risk Radiometer-Dosimeter is a low-mass and small-dimension automatic device that measures solar radiation in four channels and cosmic ionizing radiation as well. The main results of the present study include the following: (1) three different radiation sources were detected and quantified-galactic cosmic rays (GCR), energetic protons from the South Atlantic Anomaly (SAA) region of the inner radiation belt, and energetic electrons from the outer radiation belt (ORB); (2) the highest daily averaged absorbed dose rate of 426 ?Gy d(-1) came from SAA protons; (3) GCR delivered a much smaller daily absorbed dose rate of 91.1 ?Gy d(-1), and the ORB source delivered only 8.6 ?Gy d(-1). The analysis of the UV and temperature data is a subject of another article (Schuster et al., 2012 ). PMID:22680687

Dachev, Tsvetan; Horneck, Gerda; Häder, Donat-Peter; Schuster, Martin; Richter, Peter; Lebert, Michael; Demets, Rene



Time-dependent effects of exposure to static magnetic field on glucose and lipid metabolism in rat.  


In the following study, we investigate the effects of static magnetic field (SMF) (128 mT, 1 h/day during 5 or 15 consecutive days) on anthropometric parameters, glucose and lipid metabolism in rats. Exposure to SMF during 5 days induced a decrease (-8%, p < 0.05) in relative liver weight and serum insulin concentration (-56%, p < 0.001), while blood glucose level was increased (+10%, p < 0.001). By contrast, the same treatment failed to alter body weight, relative kidney weight and levels of lactate, cholesterol, triglycerides and phospholipids. Exposure to SMF during 15 days induced a decrease (-15 %, p < 0.001) in body weight, liver weight (-15 %, p < 0.05), insulin concentration (-63%, p < 0.001), plasmatic lactate level (-55%, p < 0.05) and increased glucose (+24%, p < 0.001), cholesterol (+30%, p < 0.01,) and phospholipids levels (+58%, p < 0.001), whereas, triglycerides decreased (-28%, p < 0.001). These results showed that SMF effects on glucose and lipid metabolism are time-dependent. PMID:21157002

Lahbib, Aida; Elferchichi, Myriam; Ghodbane, Soumaya; Belguith, Hatem; Chater, Sihem; Sakly, Mohsen; Abdelmelek, Hafedh



Evaluation of real-time techniques to measure hydrogen peroxide in air at the permissible exposure limit.  


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 0.5 ppm to 5 ppm. The results of this laboratory evaluation suggest that two of the four methods evaluated (the ion mobility spectrometer [IMS] and Polytron) will approximate the National Institute for Occupational Safety and Health +/- 25% accuracy requirements for measuring the concentration of VHP at and near the Occupational Safety and Health Administration permissible exposure limit of 1.0 ppm. Over the range of 0.5 ppm to 5.1 ppm VHP, the IMS had an approximate pooled method accuracy of +/- 21%, while the Polytron had a pooled method accuracy of +/- 22%. However, both instruments had false readings when exposed to nominal concentrations of methanol, bleach, and sulfur dioxide. The two additional VHP monitoring techniques evaluated (the single point monitor [SPM] and Draeger tube) were unable to accurately measure the concentration of VHP when the relative humidity was below 20%. PMID:8865593

Puskar, M A; Plese, M R



Fates of CD4+ T Cells in a Tolerant Environment Depend on Timing and Place of Antigen Exposure  

PubMed Central

In experimental organ transplantation, tolerance is induced by administration of anti-CD40L mAb in conjunction with donor-specific splenocyte transfusion. Multiple, sometimes conflicting mechanisms of action resulting from this treatment have been reported. To resolve these issues, this study assessed the fates of graft reactive cells at different times and locations in the tolerant environment. Alloantigen-specific CD4+ T cells transferred at time of tolerance induction (7 days before transplantation) became activated, expressed CD69 and CD44, and proliferated. Importantly, a large subset of this population became Foxp3+, more so in the lymph nodes than spleen, indicative of differentiation to a regulatory phenotype. In contrast, graft reactive CD4+ T cells transferred to tolerogen-treated recipients at the time of transplantation failed either to proliferate or to differentiate, and instead were deleted via apoptosis. In untreated rejecting recipients graft reactive CD4+ T cells became activated, proliferated and differentiated mainly in the spleen, and many of these cells were eventually deleted. These data resolve many apparent contradictions in the literature by showing that the timing of antigen exposure, the immunologic status of the recipients and secondary lymphoid organ location act together as key factors to determine the fate of graft reactive CD4+ T cells.

Burrell, B. E.; Bromberg, J. S.



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



Preparation and characterization of thin films by plasma polymerization of glycidoxypropyltrimethoxysilane at different plasma powers and exposure times  

NASA Astrophysics Data System (ADS)

This study aims to form a functional film on the glass substrates by plasma polymerization of glycidoxypropyltrimethoxysilane (?-GPS). Low frequency plasma generator was used to prepare plasma polymer thin films of ?-GPS (PlzP-?-GPS) on glass substrates at different plasma powers (30, 60 and 90 W) and exposure times (5, 15 and 30 min). XPS analyses were utilized to reveal the presence of functional groups in plasma polymer films. When higher plasma powers are applied, relative amount of Si-C bonds decreases and the amount of Si-O bonds increases. Contact angle measurements were performed to evaluate surface characteristics. Atomic force microscopy (AFM) studies were carried out to elucidate morphological changes. From AFM observations, it was obtained that the surface roughness slightly increased with the increase of plasma power from 30 to 90 W.

Sever, K.; Seki, Y.; Güleç, H. Ali; Sarikanat, M.; Mutlu, M.; Tavman, I.



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.



Epidermal barrier: Adverse and beneficial changes induced by ultraviolet B irradiation depending on the exposure dose and time (Review)  

PubMed Central

Exposure of the skin to ultraviolet (UV) radiation induces various harmful effects in the tissues, particularly disruption of the epidermal barrier. However, ultraviolet B (UVB) irradiation has been applied in the treatment of atopic dermatitis, a skin disease in which the epidermal barrier is defective. We reviewed the homeostasis of the epidermal barrier and several studies investigating the adverse and beneficial effects caused by different doses of UVB irradiation in the epidermal barrier. It may be concluded that, despite the harmful effects of UVB irradiation on the skin, UVB irradiation is able to exert beneficial effects in the epidermal barrier when administered in suberythemal doses and over a relatively short period of time, with no clinically evident inflammation or barrier disruption. This may be a useful therapeutic strategy for the use of UVB irradiation in the treatment of skin diseases with a disrupted epidermal barrier, such as atopic dermatitis, while reducing or avoiding the side-effects.




Reduced inter-exposure time in dual-energy imaging: a technological and image processing cooperative approach  

NASA Astrophysics Data System (ADS)

Dual-energy imaging increases the possibility of pulmonary nodule detection by reducing the bone structure noise. Dual-shot techniques are limited by structural artefacts due to patient and natural movement during the switch of voltage between energies. A new acquisition approach for dual-energy imaging was envisioned in order to reduce this inter-exposure time. The idea is to keep the tube voltage constant, switch a filter in front of the patient and thus modulate the outgoing x-ray spectrum. The drawback of this method is a poorer spectral separation between low and high energy images leading to a higher sensitivity to noise. On the other hand, noise in the reconstructed image is mainly controlled by high-energy image noise, allowing the use of noise suppression algorithms without loosing high-frequency information present in the low-energy image. The first part of this paper is a simulation study presenting system optimisation that includes noise reduction in the HE image. Exposure times and filter thickness are chosen when optimising the signal difference to noise ratio (SDNR) and dose. Results show better SDNR (9 %) for similar dose than state-of-art dual-shot switching voltage technique. Thicker filters could lead to better results, but would demand more tube charge. In the second part is presented experimental validation and implemented noise suppression algorithm. As radiographs of anatomical phantoms are structured, anisotropic algorithm have been considered. Nodule and anthropomorphic phantoms were used to measure detail suppression after image processing. Results are shown in terms of noise suppression in the reconstructed image as well as in detail preservation.

Coello, Christopher S.; Dinten, Jean-Marc; Arques, Marc; Rohr, Pierre; Odet, Christophe



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.



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



Changes in language usage of Puerto Rican mothers and their children: Do gender and timing of exposure to English matter?  

PubMed Central

This longitudinal study investigated changes in reported language usage between Puerto Rican mothers and their preschoolers over a 4-year period. It also examined whether differences in language usage occurred depending on the timing of children’s exposure to English and children’s gender. Seventy-six mothers reported the languages they and their children used when talking to each other during 2 years in Head Start, kindergarten, and first grade. Mothers of children who were exposed to Spanish and English prior to preschool entry reported using more English to their children than mothers of children who were not exposed to English until after preschool entry. The language usage of the children followed the same patterns as their mothers. The difference between the groups was maintained over the 4 years, although both groups increased their English usage. A gender effect was observed. Mothers of girls were five times more likely to use “More or All Spanish” than mothers of sons. In addition, girls who were exposed to Spanish only prior to preschool entry were six times more likely to speak to their mothers in “More or All Spanish” than other participating children. The bidimensional model of acculturation is used to present and interpret the findings.




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


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 4g/kg i.g. ethanol (25%) or water every 48h 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



Timing of deglaciation of the Gotthard Pass area, Central Swiss Alps, based on surface exposure dating with cosmogenic 10Be  

NASA Astrophysics Data System (ADS)

Mapping of glacial trimlines in the Central Swiss Alps showed the existence of two ice domes during the Last Glacial Maximum (LGM), one in the upper Rhone catchment and one in the upper Rhine catchment [1]. Between these ice domes there was an area of major ice accumulation and through-flow at the Urseren Valley. Ice from the Rhone glacier flowed down westward along the Rhone Valley but also eastward over Furka Pass towards the Urseren area. In an LGM-paleoglaciation model Gotthard Pass is a central corridor (pathway) for mass transport from north to south. Highly polished granitic rocks, crescentic gouges and other small scale glacial erosional features show that ice flowed southward from the Urseren area over the Gotthard Pass (2106 m a.s.l.) towards the Leventina Valley and the Ticino glacier. This is also shown by the continuous decrease of the trimline elevation from north to south, from about 2600 m at the Gotthard Pass to about 2500 m in the Leventina Valley. In the pass a minimum ice thickness of 480-500 m was calculated [1]. We apply surface exposure dating using cosmogenic 10Be to determine when the southward ice flow over Gotthard Pass ceased. This will show when the elevation of ice in the Urseren accumulation area was lower than the Gotthard Pass. We will present surface exposure ages from different altitudes sampled along a transect at the western Pass area. This data will be compared to exposure ages from the nearby Grimsel Pass that indicate that this Pass was ice free no later than ~14 ka BP [2]. Radiocarbon data from the Rhone Valley also suggest a deglaciation by 14 590-14 020 cal. yr BP [3]. Only slightly older (~15 000-14 300 cal. yr BP) are radiocarbon ages from the Simplon Pass [4]. Our data will be discussed within the scope of the collapse of the LGM ice domes in the Central Swiss Alps and the timing of the initial Alpine catastrophic deglaciation after the LGM. References: [1] Florineth & Schlüchter (1998), Eclogae geol. Helv. 91, 391-407. [2] Kelly et al. (2006), Boreas 35, 634-643. [3] Welten (1982), Denkschrift Schw. Naturforsch. Ges. 95, 105 pp. [4] Müller (1984), Küng: Näfels, 205 pp.

Hippe, Kristina; Ivy-Ochs, Susan; Kober, Florian; Wieler, Rainer; Schlüchter, Christian



Exposure to a Mixture of Polychlorinated Biphenyls and Polychlorinated Dibenzofurans Resulted in a Prolonged Time to Pregnancy in Women  

PubMed Central

Background Polychlorinated biphenyls (PCBs), dibenzofurans (PCDFs), and dibenzodioxins (PCDDs) may affect the female reproductive system in animals and humans. In 1978–1979, a mass poisoning occurred in central Taiwan due to PCB/PCDF-contaminated cooking oil; this incident was called Yucheng (“oil disease” in Chinese). Objective The purpose of our study was to determine whether PCB/PCDF exposure affected fertility in exposed women. Methods After the event, we followed the exposed individuals and a reference group who were sex-, age-, and community-matched. In 2003, we obtained fertility histories from Yucheng and reference women by telephone interview. We used Kaplan–Meier survival curves and multivariable Cox regression to compare time to pregnancy (TTP) between Yucheng and reference women, and we performed multiple logistic regression to determine whether PCB/PCDF exposure caused infertility. Results In total, 412 women responded, with a median TTP of 4 months in Yucheng women and 3 months in reference women (p = 0.019). After adjusting for confounders by Cox regression, we found a fecundability ratio of 0.90 [95% confidence interval (CI), 0.80–1.00] for Yucheng women. Among the 408 women who had noncontraceptive sexual activity for > 12 months, 19.7% of Yucheng women and 9.7% of reference women did not become pregnant (i.e., they were infertile). After we adjusted for confounders by logistic regression, the infertility odds ratio was 2.34 (95% CI, 1.23–4.59) for Yucheng women compared with the reference group. Conclusions We found prolonged TTP and reduced fertility among women previously exposed to PCBs/PCDFs. Because of the limited sample size and the relatively small decrease in the fertility rate, these effects require cautious interpretation and further investigation for confirmation.

Yang, Chiu-Yueh; Wang, Ying-Jan; Chen, Pau-Chung; Tsai, Shaw-Jenq; Guo, Yueliang Leon



Effect of acute bull exposure around the time of artificial insemination on serum oxytocin and progesterone concentrations and pregnancy rates in dairy cows.  


This study examined the effect of acute bull exposure around the time of artificial insemination (AI) on oxytocin and progesterone concentrations, and pregnancy rates in dairy cows. Ninety six dairy cows, stratified according to parity into primiparous and pluriparous, were divided into three groups; short bull exposure (SBE; 10 min, n = 32), long bull exposure (LBE; 4 h, n = 32) or no bull exposure (NBE; n = 32). On day 45 post-partum, all cows were treated with PGF2? on three occasions 11-14 days apart to synchronize oestrus. They were submitted to fixed time AI 80 h after the third PGF2? injection. Cows in the SBE and LBE groups were artificially inseminated 5 min after the introduction of the bull. From a subset of cows (n = 6 per group; three primiparous and three pluriparous), blood samples were collected once every 5 min starting 15 min before AI until 15 min after AI and analysed for oxytocin concentrations. Additional blood samples were collected for measurements of progesterone (P4) concentrations once daily for 4 days starting on the day of AI and once every 3 days thereafter until day 22. The effects of bull exposure, time, parity, difficulty of AI, and pregnancy on oxytocin and P4 concentrations were analysed using the mixed linear model procedure. Mean oxytocin concentrations or change in oxytocin concentrations after bull exposure or AI were not different among groups. Pregnancy rates for the NBE, SBE and LBE groups were 55.5%, 33.3% and 44.4%, respectively, and were not different among groups. In conclusion, acute bull exposure around the time of AI did not affect oxytocin and progesterone concentrations and did not improve pregnancy rates in dairy cattle under these farms conditions. PMID:22712677

Ababneh, M M; Obeidat, I N; Husein, M Q; Talafha, A Q



Air pollution exposure during critical time periods in gestation and alterations in cord blood lymphocyte distribution: a cohort of livebirths  

Microsoft Academic Search

BACKGROUND: Toxic exposures have been shown to influence maturation of the immune system during gestation. This study investigates the association between cord blood lymphocyte proportions and maternal exposure to air pollution during each gestational month. METHODS: Cord blood was analyzed using a FACSort flow cytometer to determine proportions of T lymphocytes (CD3+ cells and their subsets, CD4+ and CD8+), B

Caroline EW Herr; Miroslav Dostal; Rakesh Ghosh; Paul Ashwood; Michael Lipsett; Kent E Pinkerton; Radim Sram; Irva Hertz-Picciotto



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



The varying impact of type, timing and frequency of exposure to childhood adversity on its association with adult psychotic disorder  

PubMed Central

Background Childhood adversity has been associated with onset of psychosis in adulthood but these studies have used only general definitions of this environmental risk indicator. Therefore, we sought to explore the prevalence of more specific adverse childhood experiences amongst those with and without psychotic disorders using detailed assessments in a large epidemiological case-control sample (ÆSOP). Method Data were collected on 182 first-presentation psychosis cases and 246 geographically-matched controls in two UK centres. Information relating to the timing and frequency of exposure to different types of childhood adversity (neglect, antipathy, physical and sexual abuse, local authority care, disrupted living arrangements and lack of supportive figure) was obtained using the Childhood Experience of Care and Abuse Questionnaire. Results Psychosis cases were three times more likely to report severe physical abuse from mother that commenced prior to 12 years of age, even after adjustment for other significant forms of adversity and demographic confounders. A non-significant trend was also evident for greater prevalence of reported severe maternal antipathy amongst those with psychosis. Associations with maternal neglect and childhood sexual abuse disappeared after adjusting for maternal physical abuse and antipathy. Paternal maltreatment and other forms of adversity were not associated with psychosis nor was there evidence of a dose-response effect. Conclusions These findings suggest that only specific adverse childhood experiences are associated with psychotic disorders and only in a minority of cases. If replicated, this greater precision will ensure that research into the mechanisms underlying the pathway from childhood adversity to psychosis is more fruitful.

Fisher, Helen L.; Jones, Peter B.; Fearon, Paul; Craig, Thomas K.; Dazzan, Paola; Morgan, Kevin; Hutchinson, Gerard; Doody, Gillian A.; McGuffin, Peter; Leff, Julian; Murray, Robin M.; Morgan, Craig



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.



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  

PubMed Central

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 susceptible to clarithromycin, ethambutol, rifampin, amikacin, and the quinolones moxifloxacin, ciprofloxacin, and sparfloxacin. In terms of bactericidal activity in relation to the time of exposure these agents differed substantially with respect to the killing rate. An initial high killing capacity at low concentration was observed for amikacin, which in this respect was superior to the other agents. The bactericidal activity of clarithromycin and ethambutol was only seen at relatively high concentrations and increased with time. Killing by rifampin was concentration dependent as well as time dependent. The bactericidal activity of moxifloxacin was marginally dependent on the concentration or the time of exposure. The activity of clarithromycin in combination with ethambutol was not significantly enhanced compared to single-agent exposure. Only an additive effect was observed. The addition of rifampin or moxifloxacin as a third agent only marginally effected increased killing of MAC. However, by addition of amikacin the activity of the clarithromycin-ethambutol combination was significantly improved. The combination of amikacin and amoxicillin-clavulanic acid exhibited synergistic antimycobacterial activity. Towards MAC at low growth rates, only the quinolones exhibited a bactericidal effect.

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



Infection of the malaria mosquito, Anopheles gambiae, with two species of entomopathogenic fungi: effects of concentration, co-formulation, exposure time and persistence  

PubMed Central

Background Entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana isolates have been shown to infect and reduce the survival of mosquito vectors. Methods Here four different bioassays were conducted to study the effect of conidia concentration, co-formulation, exposure time and persistence of the isolates M. anisopliae ICIPE-30 and B. bassiana I93-925 on infection and survival rates of female Anopheles gambiae sensu stricto. Test concentrations and exposure times ranged between 1 × 107 - 4 × 1010 conidia m-2 and 15 min - 6 h. In co-formulations, 2 × 1010 conidia m-2 of both fungus isolates were mixed at ratios of 4:1, 2:1, 1:1,1:0, 0:1, 1:2 and 1:4. To determine persistence, mosquitoes were exposed to surfaces treated 1, 14 or 28 d previously, with conidia concentrations of 2 × 109, 2 × 1010 or 4 × 1010. Results Mosquito survival varied with conidia concentration; 2 × 1010 conidia m-2 was the concentration above which no further reductions in survival were detectable for both isolates of fungus. The survival of mosquitoes exposed to single and co-formulated treatments was similar and no synergistic or additive effects were observed. Mosquitoes were infected within 30 min and longer exposure times did not result in a more rapid killing effect. Fifteen min exposure still achieved considerable mortality rates (100% mortality by 14 d) of mosquitoes, but at lower speed than with 30 min exposure (100% mortality by 9 d). Conidia remained infective up to 28 d post-application but higher concentrations did not increase persistence. Conclusion Both fungus isolates are effective and persistent at low concentrations and short exposure times.




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...


The protective effect of a 17°C holding time on boar sperm plasma membrane fluidity after exposure to 5°C.  


The holding time (HT) is the period during which an ejaculate, either in a raw or diluted state, is held at 17°C before further processing for cold-storage. In boars, the HT positively influences select sperm quality parameters of semen cooled from 15 to 5°C, a range in temperature during which plasma membrane remodeling occurs. Objective insight into the effect of HT on plasma membrane organization remains unknown. Therefore, the present work sought to elucidate if HT contributes to minimizing alterations in boar sperm plasma membrane fluidity at the initial step of the cooling process in a cryopreservation practice (holding at 5°C) and in relation with select sperm quality parameters. Nineteen ejaculates from five boars were collected and processed according to different treatments: T1) Fresh diluted semen, 0h at 17°C; T2) Fresh diluted semen, 24h at 17°C (HT); T3) Sperm from T1 in a lactose-egg yolk (LEY) extender, 3h at 5°C; T4) Sperm from T2 in LEY, 3h at 5°C; T5) Sperm from T1 in LEY, 24h at 5°C; T6) Sperm from T2 in LEY, 24h at 5°C. Sperm motility was assessed using CASA, and sperm plasma membrane integrity and fluidity were evaluated by flow cytometry with dual labeling (M540/YO-PRO®-1). Results demonstrated that the lack of exposure to a HT (T5) results in reduced sample motility compared to those having a HT (T6), with sperm exposed to HT exhibiting less plasma membrane fluidity. Collectively, these results provide empirical evidence that incorporation of a HT in semen processing protects boar sperm against cold injury through maintenance of lipid architecture of the plasma membrane. PMID:23219919

Casas, I; Althouse, G C



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




EPA Science Inventory

Real-time monitors and low-volume air samplers were used 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. Three...


Effects of exposure time on variations in the structure and hydrophobicity of polyvinylidene fluoride membranes prepared via vapor-induced phase separation  

NASA Astrophysics Data System (ADS)

The present investigation revealed how the surface morphology and hydrophobicity of polyvinylidene fluoride (PVDF) membranes, which were prepared via a vapor-induced phase separation (VIPS) method, were affected by the exposure time. The mass variation of the cast film was recorded. Membrane morphologies were observed by scanning electron microscopy (SEM) and thermal behaviors of membranes were examined by differential scanning calorimetry (DSC). Wide angle X-ray diffraction (WAXD) was employed to analyze the crystalline structures of the overall membranes and the surface layers. The results showed that different membrane morphologies and hydrophobicities could be obtained by changing the exposure time. A long exposure time facilitated the crystallization process, resulting in the formation of a porous skin and particle morphology, which increased the hydrophobicity of the surface. A short exposure time favored the formation of a digitate macrovoid and dense skin resulting from liquid-liquid phase separation in the immersion process, which reduced surface hydrophobicity. The water permeate flux in vacuum membrane distillation was greatly affected by the membrane porosity and surface hydrophobicity.

Peng, Yuelian; Fan, Hongwei; Dong, Yajun; Song, Yanna; Han, Hua



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  

Microsoft Academic Search

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

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



Antibacterial activity of oregano oil against antibiotic resistant Salmonella enterica on organic leafy greens at varying exposure times and storage temperatures  

Technology Transfer Automated Retrieval System (TEKTRAN)

The objective of this study was to evaluate the effectiveness of oregano oil on four organic leafy greens (iceberg and romaine lettuces and mature and baby spinaches) inoculated with Salmonella Newport as a function of treatment exposure times as well as storage temperatures. Leaf samples were wash...


Effects of exposure time and cognitive operations on facial identification accuracy: a meta-analysis of two variables associated with initial memory strength  

Microsoft Academic Search

In the present study, we conducted two separate meta-analyses in order to quantify the influence on facial identification accuracy of two variables related to initial memory strength for an unfamiliar face, specifically, length of exposure at the time of encounter and encoding operations as manipulated via stimulus processing instructions. Proportion correct was significantly higher for longer (M = 0.66) as

Brian H. Bornstein; Kenneth A. Deffenbacher; Steven D. Penrod; E. Kiernan McGorty



Effects of exposure time and cognitive operations on facial identification accuracy: a meta-analysis of two variables associated with initial memory strength  

Microsoft Academic Search

In the present study, we conducted two separate meta-analyses in order to quantify the influence on facial identification accuracy of two variables related to initial memory strength for an unfamiliar face, specifically, length of exposure at the time of encounter and encoding operations as manipulated via stimulus processing instructions. Proportion correct was significantly higher for longer (M = 0.66) as

Brian H. Bornstein; Kenneth A. Deffenbacher; Steven D. Penrod; E. Kiernan McGorty



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.



Regularly scheduled, day-time, slow-onset 60 Hz electric and magnetic field exposure does not depress serum melatonin concentration in nonhuman primates  

SciTech Connect

Experiments conducted with laboratory rodents indicate that exposure to 60 Hz electric fields or magnetic fields can suppress nocturnal melatonin concentrations in pineal gland and blood. In three experiments employing three field-exposed and three sham-exposed nonhuman primates, each implanted with an indwelling venous cannula to allow repeated blood sampling, the authors studied the effects of either 6 kV/m and 50 {micro}T (0.5 G) or 30 kV/m and 100 {micro}T (1.0 G) on serum melatonin patterns. The fields were ramped on and off slowly, so that no transients occurred. Extensive quality control for the melatonin assay, computerized control and monitoring of field intensities, and consistent exposure protocols were used. No changes in nocturnal serum melatonin concentration resulted from 6 weeks of day-time exposure with slow field onset/offset and a highly regular exposure protocol. These results indicate that, under the conditions tested, day-time exposure to 60 Hz electric and magnetic fields in combination does not result in melatonin suppression in primates.

Rogers, W.R.; Smith, H.D.; Orr, J.L. [Southwest Research Inst., San Antonio, TX (United States); Reiter, R.J.; Barlow-Walden, L. [Univ. of Texas Health Science Center, San Antonio, TX (United States)



Effect of an acute 900MHz GSM exposure on glia in the rat brain: a time-dependent study.  


Because of the increasing use of mobile phones, the possible risks of radio frequency electromagnetic fields adverse effects on the human brain has to be evaluated. In this work we measured GFAP expression, to evaluate glial evolution 2, 3, 6 and 10 days after a single GSM exposure (15min, brain averaged SAR=6W/kg, 900MHz signal) in the rat brain. A statistically significant increase of GFAP stained surface area was observed 2 days after exposure in the frontal cortex and the caudate putamen. A smaller statistically significant increase was noted 3 days after exposure in the same areas and in the cerebellum cortex. Our results confirm the Mausset-Bonnefont et al. study [Mausset-Bonnefont, A.L., Hirbec, H., Bonnefont, X., Privat, A., Vignon, J., de Seze, R., 2004. Acute exposure to GSM 900MHz electromagnetic fields induces glial reactivity and biochemical modifications in the rat brain. Neurobiol. Dis. 17, 445-454], showing the existence of glial reactivity after a 15min GSM acute exposure at a brain averaged SAR of 6W/kg. We conclude to a temporary effect, probably due to a hypertrophy of glial cells, with a temporal and a spatial modulation of the effect. Whether this effect could be harmful remains to be studied. PMID:17624651

Brillaud, Elsa; Piotrowski, Aleksandra; de Seze, René



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



Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae) HP88 for biological control of Rhipicephalus microplus (Acari: Ixodidae): the effect of different exposure times of engorged females to the nematodes.  


The aim of this study was to assess the influence of different exposure times of engorged female the Rhipicephalus microplus to infective juveniles of Heterorhabditis bacteriophora isolate HP88. The engorged females were divided into seven groups (six treatments and one control) of 20 ticks each with statistically similar average weights (p>0.05) and exposed to concentrations of 300 nematodes/tick for periods of 3, 6, 12, 24, 48 and 72 h. The following biological parameters were monitored: pre-oviposition period; egg mass weight; hatching percentage; and efficacy of treatment. There was no influence of the exposure time on the pre-oviposition period (p>0.05), while there were significant differences (p<0.05) between the groups exposed for 24, 48 and 72 h and the control group with respect to the egg mass weight, and 24h for hatching percentage. Treatment efficacy reached 100% after exposure for 48 and 72 h. These results demonstrate that infective juveniles of H. bacteriophora HP88, under laboratory conditions, interfere in the majority of the biological parameters of the non-parasitic phase of engorged R. microplus females when the exposure time is greater than or equal to 24h. PMID:22093907

Monteiro, Caio Márcio de Oliveira; Prata, Márcia Cristina de Azevedo; Faza, Aline; Batista, Elder Simões de Paula; Dolinski, Cláudia; Furlong, John



Air pollution exposure during critical time periods in gestation and alterations in cord blood lymphocyte distribution: a cohort of livebirths  

PubMed Central

Background Toxic exposures have been shown to influence maturation of the immune system during gestation. This study investigates the association between cord blood lymphocyte proportions and maternal exposure to air pollution during each gestational month. Methods Cord blood was analyzed using a FACSort flow cytometer to determine proportions of T lymphocytes (CD3+ cells and their subsets, CD4+ and CD8+), B lymphocytes (CD19+) and natural killer (NK) cells. Ambient air concentrations of 12 polycyclic aromatic hydrocarbons (PAH) and particulate matter < 2.5 micrometer in diameter (PM2.5) were measured using fixed site monitors. Arithmetic means of these pollutants, calculated for each gestational month, were used as exposure metrics. Data on covariates were obtained from medical records and questionnaires. Multivariable linear regression models were fitted to estimate associations between monthly PAH or PM2.5 and cord blood lymphocytes, adjusting for year of birth and district of residence and, in further models, gestational season and number of prior live births. Results The adjusted models show significant associations between PAHs or PM2.5 during early gestation and increases in CD3+ and CD4+ lymphocytes percentages and decreases in CD19+ and NK cell percentages in cord blood. In contrast, exposures during late gestation were associated with decreases in CD3+ and CD4+ fractions and increases in CD19+ and NK cell fractions. There was no significant association between alterations in lymphocyte distribution and air pollution exposure during the mid gestation. Conclusions PAHs and PM2.5 in ambient air may influence fetal immune development via shifts in cord blood lymphocytes distributions. Associations appear to differ by exposure in early versus late gestation.



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.



Real-time measurement of cytosolic free calcium concentration in HL-60 cells during static magnetic field exposure and activation by ATP.  


Calcium ions are involved in a number of important signal transduction pathways in cells. Cytosolic calcium concentration ([Ca(2+)](c)) can be affected by the activation of Ca(2+) channels through the action of ligands such as ATP. The response of [Ca(2+)](c) to ligands may be affected by external factors like magnetic fields. The purpose of this study was to determine if exposure to a static magnetic field (SMF) for 800 s altered the [Ca(2+)](c) response to ATP in undifferentiated HL-60 cells. We sham exposed or field exposed fura-2 loaded HL-60 cells to a SMF of 1, 10, and 100 mT. Cells were activated with ATP 300 s into the exposure. The level of [Ca(2+)](c) was followed before, during, and after field or sham exposure with a ratiometric fluorescence spectroscopy system. It was found that high concentrations of ATP resulted in greater [Ca(2+)](c) responses, but faster recovery to near basal levels. The application of 1, 10, or 100 mT SMF did not affect the [Ca(2+)](c) response to ATP. Future work could examine the effect of a longer SMF exposure on the [Ca(2+)](c) response to ATP. Longer exposures might provide sufficient time for morphological changes in the plasma membrane to occur. PMID:18338328

Belton, Michelle; Commerford, Kristy; Hall, Justin; Prato, Frank S; Carson, Jeffrey J L



The relationship between daytime exposure to light and night-time sleep in 6-12-week-old infants  

Microsoft Academic Search

SUMMARY This project investigated the relationship between exposure to light and 24-h patterns of sleep and crying in young, healthy, full-term babies living at home and following a normal domestic routine. Measures included an ankle worn activity monitor, an external light monitor and the Barr Baby Day Diary in which parents recorded periods of sleep, crying, feeding and other behaviours

Yvonne Harrison



Predicting changes in PM exposure over time at U.S. trucking terminals using structural equation modeling techniques.  


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 microm 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 microg/m(3); period 2 = 0.94 microg/m(3)) and outdoor background location (median EC: period 1 = 0.46 microg/m(3); period 2 = 0.67 microg/m(3)), as well as in the truck cabs of local drivers while on the road (median EC: period 1 = 1.09 microg/m(3); period 2 = 1.07 microg/m(3)). 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. PMID:19367483

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



The measurement of the isoflavone daidzein by time resolved fluorescent immunoassay: a method for assessment of dietary soya exposure  

Microsoft Academic Search

We report a novel method for the measurement of urinary daidzein that is suitable for assessment of dietary soya exposure. The method incorporates the following features: (i) a highly specific monoclonal antibody to daidzein (clone 4E4) raised through the 7 position of daidzein and (ii) a europium labeled ovalbumin daidzein conjugate. In the present format, dilute urine samples of subjects

F. Kohen; S. Lichter; B. Gayer; J. DeBoever; L. J. W. Lu



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.



Transfer of indoxacarb among workers of Coptotermes formosanus (Isoptera: Rhinotermitidae): effects of dose, donor:recipient ratio and post-exposure time.  


Horizontal transfer of indoxacarb among workers of the Formosan subterranean termite, Coptotermes formosanus Shiraki, was examined under laboratory conditions. The effects of dose (0, 10, 20, 50, 100 or 200 ng AI per donor), donor:recipient ratio (1:1, 1:4 or 1:9) and post-exposure time (2, 4, 8, 16, 20 and 24 days) on lethal transfer of indoxacarb were investigated using a donor/recipient model in groups of 100 workers. Transfer of lethal doses from donors to recipients was evidenced by significant recipient mortality in 13 out of 15 treatments within 24 days post-exposure. Dosage significantly affected indoxacarb transfer. Higher doses resulted in greater recipient mortality than lower doses. The highest dose tested resulted in 100% death of recipients and donors within 20 days. A dose of 100 ng resulted in recipient mortalities ranging from 68 to 100%, whereas doses < or =50 ng killed <60% of recipients within 24 days. Donor:recipient ratio also had considerable effect on indoxacarb transfer. At 24 days post-exposure, greater recipient mortalities were observed at ratios > or =1:4 at doses > or =20 ng, but only at a ratio 1:1 at dose 10 ng. Recipient mortality increased significantly as post-exposure time increased. The higher the doses applied on donors, the shorter were the times required for the onset of recipient mortality to occur and for recipients to reach maximum mortality. Significantly greater recipient mortalities were not observed at doses 20 and 50 ng until more than 20 days post-exposure, indicating a delayed activity of indoxacarb. Possible transfer mechanisms are discussed. PMID:16235268

Hu, Xing Ping; Song, Dunlun; Scherer, Clay W



Effects of indoxacarb concentration and exposure time on onset of abnormal behaviors, morbundity, and death in eastern subterranean termite (Isoptera: Rhinotermitidae).  


Onset of abnormal behaviors, morbundity, and death was evaluated in eastern subterranean termites, Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), exposed to several concentrations (45, 90, 135, and 180 ppm) of indoxacarb and to several (5, 10, 20, 40, 80, and 160 min) exposure periods. Abnormal behaviors, morbundity, and death occurred in a predictable sequence: disorientation, ataxia, and morbundity followed by death. In general, higher concentrations and longer exposure periods resulted in faster onset of abnormal behaviors, morbundity, and death. The average onset time of abnormal behaviors, morbundity, and death was faster for groups of termites compared with individuals exposed to similar concentrations and periods of contact. The importance of onset times of abnormal behaviors as another important measure of the toxicity of slow-acting toxicants is discussed. PMID:20568622

Quarcoo, Franklin Y; Appel, Arthur G; Hu, Xing Ping



Effects of brief cutaneous JP-8 jet fuel exposures on time course of gene expression in the epidermis.  


The jet fuel jet propulsion fuel 8 (JP-8) has been shown to cause an inflammatory response in the skin, which is characterized histologically by erythema, edema, and hyperplasia. Studies in laboratory animal skin and cultured keratinocytes have identified a variety of changes in protein levels related to inflammation, oxidative damage, apoptosis, and cellular growth. Most of these studies have focused on prolonged exposures and subsequent effects. In an attempt to understand the earliest responses of the skin to JP-8, we have investigated changes in gene expression in the epidermis for up to 8 h after a 1-h cutaneous exposure in rats. After exposure, we separated the epidermis from the rest of the skin with a cryotome and isolated total mRNA. Gene expression was studied with microarray techniques, and changes from sham treatments were analyzed and characterized. We found consistent twofold increases in gene expression of 27 transcripts at 1, 4, and 8 h after the beginning of the 1-h exposure that were related primarily to structural proteins, cell signaling, inflammatory mediators, growth factors, and enzymes. Analysis of pathways changed showed that several signaling pathways were increased at 1 h and that the most significant changes at 8 h were in metabolic pathways, many of which were downregulated. These results confirm and expand many of the previous molecular studies with JP-8. Based on the 1-h changes in gene expression, we hypothesize that the trigger of the JP-8-induced, epidermal stress response is a physical disruption of osmotic, oxidative, and membrane stability which activates gene expression in the signaling pathways and results in the inflammatory, apoptotic, and growth responses that have been previously identified. PMID:17085751

McDougal, James N; Garrett, Carol M; Amato, Carol M; Berberich, Steven J



Use of bull exposure in a Gonadotropin-releasing hormone-based estrous synchronization protocol that included fixed-time artificial insemination in first- calf suckled beef cows  

Microsoft Academic Search

The objective was to evaluate whether exposing primiparous suckled beef cows to the biostimulatory effect of bulls alters breeding performance associated with an estrous synchronization (ES) protocol that included GnRH, PGF2? (PG), and fixed-time AI. This is a composite analysis of 3 experiments that evaluated: 1) effects of bull exposure at different d after calving (Yr 1); 2) biostimulatory effects

James G. Berardinelli


Analysis of real-time variables affecting children's exposure to diesel-related pollutants during school bus commutes in Los Angeles  

Microsoft Academic Search

Variables affecting children's exposure during school bus commutes were investigated using real-time measurements of black carbon (BC), particle-bound polycyclic aromatic hydrocarbons (PB-PAH) and nitrogen dioxide (NO2) inside 3 conventional diesel school buses, a particle trap-outfitted (TO) diesel school bus and a compressed natural gas (CNG) school bus, while traveling along an urban Los Angeles Unified School District bus route. A

Lisa D. Sabin; Kathleen Kozawa; Eduardo Behrentz; Arthur M. Winer; Dennis R. Fitz; David V. Pankratz; Steven D. Colome; Scott A. Fruin



Evaluation of reaction time performance and subjective workload during whole-body vibration exposure while seated in upright and twisted postures with and without armrests  

Microsoft Academic Search

There is little knowledge on performance during vibration exposure combined with occupational hazards such as bent or twisted postures. In addition, little information is available on the effective use of armrests during performance-related tasks. This paper investigates the influence of sitting in different working postures on the reaction time and perceived workload of subjects exposed to whole-body vibration. Twenty-one subjects

Geraldine S. Newell; Neil J. Mansfield



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.



Subsidized childcare and child development in Colombia: Effects of Hogares Comunitarios de Bienestar as a function of timing and length of exposure.  


Rigorous evidence regarding the impact of early care and education on children's development comes primarily from high-income nations. A few studies from Latin America and the Caribbean have identified benefits of conditional cash transfer and home visiting programs on children's development. However, there is still controversy around the impact and cost-effectiveness of childcare approaches. Further research is needed to understand how scaled-up childcare settings may support the development of low-income children in Latin America. To that end, the present study sought to identify the effects of exposure to a subsidized childcare program in Colombia on children's nutritional status, cognitive and socioemotional development. This community-based program, known as Hogares Comunitarios de Bienestar (HCB), serves 800 thousand low-income children under age 6, delivering home-based childcare, supplementary nutrition, and psychosocial stimulation. We analyzed data on 10,173 program beneficiary children (ages 3-6) collected in 2007. We compared beneficiary children who had been in the program for a long time with beneficiary children who had been in the program for a month or less, by age group, to estimate program exposure effects. We used a matching estimator to correct for self-selection into different exposure levels. Results indicated that cognitive development improved 0.15 to 0.3 of a standard deviation (SD) after at least 15 months of exposure for children between 3 and 6 years of age. Socioemotional skills improved 0.12 to 0.3 SD for children older than 3 after at least 15 months of program exposure. No significant gains were found for nutritional status. The estimated benefit-cost ratio ranged from 1.0 to 2.7, depending upon varying discount rates. Findings lend support for a potentially effective strategy to promote the development of low-income children in Colombia and other developing nations. PMID:23312302

Bernal, Raquel; Fernández, Camila



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.



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.



Effect of exposure time on the accuracy and reliability of cone beam computed tomography in the assessment of dental implant site dimensions in dry skulls  

PubMed Central

Objectives To investigate the accuracy and reliability of implant site measurements, recorded from low-dose cone beam computed tomography (CBCT) images. Methods CBCT reformatted images of five skulls were obtained using 40, 20 and 7 s exposure protocols. From these protocols, edentulous ridge dimensions were recorded by two observers and compared with measurements recorded directly from the bone. The measurement errors and intra- and inter-examiner reliability were calculated for each exposure protocol and compared with each other. Results The mean absolute errors from the 40, 20 and 7 s protocols were 0.50, 0.46, and 0.51 mm, respectively. The intra-examiner reliability scores were 0.996, 0.995 and 0.998, respectively. The inter-examiner reliability scores were 0.993, 0.998 and 0.994, respectively. There was no significant difference in accuracy or reliability between the three protocols. Conclusions In imaging of dry skulls, lowering the CBCT exposure time from 40 s to 20 or 7 s does not affect the reliability or accuracy of implant site measurements.

Al-Ekrish, Asmaa A.



Individual-Level PM2.5 Exposure and the Time Course of Impaired Heart Rate Variability--The APACR Study  

PubMed Central

We examined, in 106 community-dwelling middle-aged non-smokers, the time-course and the acute effects of fine particles (PM2.5) on heart rate variability (HRV), which measures cardiac autonomic modulation (CAM). 24-hour 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-hour individual-level real-time PM2.5 exposures. We use linear mixed-effects models to assess autocorrelation- and other major confounder-adjusted regression coefficients between 1-6 hour moving averages of PM2.5 and HRV indices. The increases in preceding 1-6 hour moving averages of PM2.5 was significantly associated with lower HF, LF, and SDNN, with the largest effect size at 4-6 hour moving averages and smallest effects size at 1 hour moving average. For example, a 10 ?g/m3 increase in 1-hour and 6-hour 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). PM2.5 exposures are associated with immediate impairment of CAM. With a time-course of within 6 hours after elevated PM2.5 exposure, with the largest effects around 4-6 hours.

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



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.  


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



Acute exposure to mercury from amalgam: no short-time effect on the peripheral blood lymphocytes in healthy individuals.  


Mercury, released from dental amalgam, has been considered to adversely affect the human immune system. This study has been performed in order to evaluate if an acute low-dose mercury exposure, achieved by total amalgam removal in 10 healthy individuals, would affect the immunocompetent cells in human blood when the mercury level in blood and plasma was increasing. Induction of lymphocyte proliferation, measured as spontaneous de novo DNA synthesis, and total T cells, CD4+ T cells, CD8+ T cells, and B cells, was studied prior to and 7, 31, and 48 h after amalgam removal. In addition, the levels of interleukin-6 (IL-6) and C-reactive protein (CRP) in serum/plasma were measured. Despite a significant increase of the plasma mercury levels within 24 h after intervention, no significant influence on the peripheral blood lymphocytes could be detected during the first 48 h. The serum IL-6 levels increased significantly within 48 h after intervention, but were still low and within normal range. No influence on the CRP levels up to 7 d after amalgam removal was detected. PMID:9726779

Loftenius, A; Sandborgh-Englund, G; Ekstrand, J




ERIC Educational Resources Information Center

Presents brief annotations of 41 children's books that explore the concept of time from varied perspectives to elucidate some of its meanings for children. Groups books to focus on milestones in children's lives; how they enjoy spending their time; visiting the past in suspending time; recognizing different ways to mark time; celebrating special…

Matthews, Susan; Reid, Rebecca; Sylvan, Anne; Woolard, Linda; Freeman, Evelyn B.



Real-time in situ electron spin resonance measurements on fungal spores of Penicillium digitatum during exposure of oxygen plasmas  

NASA Astrophysics Data System (ADS)

We report the kinetic analysis of free radicals on fungal spores of Penicillium digitatum interacted with atomic oxygen generated plasma electric discharge using real time in situ electron spin resonance (ESR) measurements. We have obtained information that the ESR signal from the spores was observed and preliminarily assignable to semiquinone radical with a g-value of around 2.004 and a line width of approximately 5G. The decay of the signal is possibly linked to the inactivation of the fungal spore. The real-time in situ ESR has proven to be a useful method to elucidate plasma-induced surface reactions on biological specimens.

Ishikawa, Kenji; Mizuno, Hiroko; Tanaka, Hiromasa; Tamiya, Kazuhiro; Hashizume, Hiroshi; Ohta, Takayuki; Ito, Masafumi; Iseki, Sachiko; Takeda, Keigo; Kondo, Hiroki; Sekine, Makoto; Hori, Masaru



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



Antimicrobial activity of oregano oil against antibiotic-resistant Salmonella enterica on organic leafy greens at varying exposure times and storage temperatures.  


The objective of this study was to evaluate the effectiveness of oregano oil on four organic leafy greens (Iceberg and Romaine lettuces and mature and baby spinaches) inoculated with Salmonella Newport as a function of treatment exposure times as well as storage temperatures. Leaf samples were washed, dip inoculated with S. Newport (6-log CFU/ml) and dried. Oregano oil was prepared at 0.1, 0.3, and 0.5% concentrations in sterile phosphate buffered saline (PBS). Inoculated leaves were immersed in the treatment solution for 1 or 2 min, and individually incubated at 4 or 8 °C. Samples were taken at day 0, 1, and 3 for enumeration of survivors. The results showed that oregano oil was effective against S. Newport at all concentrations. S. Newport showed reductions from the PBS control of 0.7-4.8 log CFU/g (Romaine lettuce), 0.8-4.8 log CFU/g (Iceberg lettuce), 0.8-4.9 log CFU/g (mature spinach), and 0.5-4.7 log CFU/g (baby spinach), respectively. The antibacterial activity also increased with exposure time. Leaf samples treated for 2 min generally showed greater reductions (by 1.4-3.2 log CFU/g), than those samples treated for 1 min; however, there was minimal difference in antimicrobial activity among samples stored under refrigeration and abuse temperatures. This study demonstrates the potential of oregano oil to inactivate S. Newport on organic leafy greens. PMID:23498188

Moore-Neibel, Katherine; Gerber, Colin; Patel, Jitendra; Friedman, Mendel; Jaroni, Divya; Ravishankar, Sadhana



Exposure to hot and cold temperatures and ambulance attendances in Brisbane, Australia: a time-series study  

PubMed Central

Objectives To investigate the effect of hot and cold temperatures on ambulance attendances. Design An ecological time-series study. Setting and participants The study was conducted in Brisbane, Australia. The authors collected information on 783?935 daily ambulance attendances, along with data of associated meteorological variables and air pollutants, for the period of 2000–2007. Outcome measures The total number of ambulance attendances was examined, along with those related to cardiovascular, respiratory and other non-traumatic conditions. Generalised additive models were used to assess the relationship between daily mean temperature and the number of ambulance attendances. Results There were statistically significant relationships between mean temperature and ambulance attendances for all categories. Acute heat effects were found with a 1.17% (95% CI 0.86% to 1.48%) increase in total attendances for 1°C increase above threshold (0–1?days lag). Cold effects were delayed and longer lasting with a 1.30% (0.87% to 1.73%) increase in total attendances for a 1°C decrease below the threshold (2–15?days lag). Harvesting was observed following initial acute periods of heat effects but not for cold effects. Conclusions This study shows that both hot and cold temperatures led to increases in ambulance attendances for different medical conditions. Our findings support the notion that ambulance attendance records are a valid and timely source of data for use in the development of local weather/health early warning systems.

Turner, Lyle R; Connell, Des



Choline supplementation attenuates learning deficits associated with neonatal alcohol exposure in the rat: effects of varying the timing of choline administration.  


Despite the harmful effects of fetal alcohol exposure, some pregnant women continue to drink alcohol. Thus, it is imperative to pursue safe, effective treatments for children with fetal alcohol spectrum disorders. Using an animal model, our laboratory has demonstrated that choline, an essential nutrient, effectively reduces the severity of some fetal alcohol effects, even when administered after the ethanol insult is complete. The present study investigated whether there is a critical developmental period when choline is most effective in attenuating ethanol's teratogenic effects. Sprague-Dawley rats were exposed to 5.25 g/kg/day ethanol during the third trimester equivalent brain growth spurt (postnatal days (PD) 4-9) via intubation. A non-intubation control group and a sham intubation control group were included. Following ethanol exposure, pups received subcutaneous injections of saline vehicle or choline chloride (100 mg/kg/day) from PD 11-20, PD 21-30, or PD 11-30. Beginning on PD 45, subjects were tested on a Morris water maze spatial learning task. Performance of both the ethanol-exposed group that did not receive choline and the ethanol-exposed group treated with choline from PD 21-30 was significantly impaired compared to controls during acquisition of the Morris water maze task. Performance of ethanol-exposed groups treated with choline from PD 11-20 or PD 11-30 was intermediate, not differing significantly from any other groups. However, during the probe trial, ethanol exposure produced significant deficits in spatial memory which were mitigated by all choline treatments, regardless of the timing of administration. These findings suggest that choline's therapeutic window may be very large, or spans across the two developmental periods examined in this study. Importantly, these findings indicate that choline supplementation may effectively reduce some alcohol-related learning impairments, even when administered in later childhood. PMID:18786517

Ryan, S Hunter; Williams, Jennifer K; Thomas, Jennifer D



Effect of concentration and exposure time on treatment efficacy against Varroa mites (Acari: Varroidae) during indoor winter fumigation of honey bees (Hymenoptera: Apidae) with formic acid.  


The combination of the concentration of formic acid and the duration of fumigation (CT product) during indoor treatments of honey bee, Apis mellifera L., colonies to control the varroa mite, Varroa destructor Anderson & Trueman, determines the efficacy of the treatment. Because high concentrations can cause queen mortality, we hypothesized that a high CT product given as a low concentration over a long exposure time rather than as a high concentration over a short exposure time would allow effective control of varroa mites without the detrimental effects on queens. The objective of this study was to assess different combinations of formic acid concentration and exposure time with similar CT products in controlling varroa mites while minimizing the effect on worker and queen honey bees. Treated colonies were exposed to a low, medium, or high concentration of formic acid until a mean CT product of 471 ppm*d in room air was realized. The treatments consisted of a long-term low concentration of 19 ppm for 27 d, a medium-term medium concentration of 42 ppm for 10 d, a short-term high concentration of 53 ppm for 9 d, and an untreated control. Both short-term high-concentration and medium-term medium-concentration fumigation with formic acid killed varroa mites, with averages of 93 and 83% mortality, respectively, but both treatments also were associated with an increase in mortality of worker bees, queen bees, or both. Long-term low-concentration fumigation had lower efficacy (60% varroa mite mortality), but it did not increase worker or queen bee mortality. This trend differed slightly in colonies from two different beekeepers. Varroa mite mean abundance was significantly decreased in all three acid treatments relative to the control. Daily worker mortality was significantly increased by the short-term high concentration treatment, which was reflected by a decrease in the size of the worker population, but not an increase in colony mortality. Queen mortality was significantly greater under the medium-term medium concentration and the short-term high concentration treatments than in controls. PMID:16539097

Underwood, Robyn M; Currie, Robert W



Microbial activity and community diversity in a variable charge soil as affected by cadmium exposure levels and time*  

PubMed Central

Effects of cadmium (Cd) on microbial biomass, activity and community diversity were assessed in a representative variable charge soil (Typic Aquult) using an incubation study. Cadmium was added as Cd(NO3)2 to reach a concentration range of 0~16 mg Cd/kg soil. Soil extractable Cd generally increased with Cd loading rate, but decreased with incubation time. Soil microbial biomass was enhanced at low Cd levels (0.5~1 mg/kg), but was inhibited consistently with increasing Cd rate. The ratio of microbial biomass C/N varied with Cd treatment levels, decreasing at low Cd rate (<0.7 mg/kg available Cd), but increasing progressively with Cd loading. Soil respiration was restrained at low Cd loading (<1 mg/kg), and enhanced at higher Cd levels. Soil microbial metabolic quotient (MMQ) was generally greater at high Cd loading (1~16 mg/kg). However, the MMQ is also affected by other factors. Cd contamination reduces species diversity of soil microbial communities and their ability to metabolize different C substrates. Soils with higher levels of Cd contamination showed decreases in indicator phospholipids fatty acids (PLFAs) for Gram-negative bacteria and actinomycetes, while the indicator PLFAs for Gram-positive bacteria and fungi increased with increasing levels of Cd contamination.

Shentu, Jia-li; He, Zhen-li; Yang, Xiao-e; Li, Ting-qiang



Combination of a higher-tier flow-through system and population modeling to assess the effects of time-variable exposure of isoproturon on the green algae Desmodesmus subspicatus and Pseudokirchneriella subcapitata.  


A flow-through system was developed to investigate the effects of time-variable exposure of pesticides on algae. A recently developed algae population model was used for simulations supported and verified by laboratory experiments. Flow-through studies with Desmodesmus subspicatus and Pseudokirchneriella subcapitata under time-variable exposure to isoproturon were performed, in which the exposure patterns were based on the results of FOrum for Co-ordination of pesticide fate models and their USe (FOCUS) model calculations for typical exposure situations via runoff or drain flow. Different types of pulsed exposure events were realized, including a whole range of repeated pulsed and steep peaks as well as periods of constant exposure. Both species recovered quickly in terms of growth from short-term exposure and according to substance dissipation from the system. Even at a peak 10 times the maximum predicted environmental concentration of isoproturon, only transient effects occurred on algae populations. No modified sensitivity or reduced growth was observed after repeated exposure. Model predictions of algal growth in the flow-through tests agreed well with the experimental data. The experimental boundary conditions and the physiological properties of the algae were used as the only model input. No calibration or parameter fitting was necessary. The combination of the flow-through experiments with the algae population model was revealed to be a powerful tool for the assessment of pulsed exposure on algae. It allowed investigating the growth reduction and recovery potential of algae after complex exposure, which is not possible with standard laboratory experiments alone. The results of the combined approach confirm the beneficial use of population models as supporting tools in higher-tier risk assessments of pesticides. PMID:22328269

Weber, Denis; Schaefer, Dieter; Dorgerloh, Michael; Bruns, Eric; Goerlitz, Gerhard; Hammel, Klaus; Preuss, Thomas G; Ratte, Hans Toni



Real-time and time-integrated PM2.5 and CO from prescribed burns in chipped and non-chipped plots: firefighter and community exposure and health implications.  


In this study, smoke data were collected from two plots located on the Francis Marion National Forest in South Carolina during prescribed burns on 12 February 2003. One of the plots had been subjected to mechanical chipping, the other was not. This study is part of a larger investigation of fire behavior related to mechanical chipping, parts of which are presented elsewhere. The primary objective of the study reported herein was to measure PM(2.5) and CO exposures from prescribed burn smoke from a mechanically chipped vs. non-chipped site. Ground-level time-integrated PM(2.5) samplers (n=9/plot) were placed at a height of 1.5 m around the sampling plots on the downwind side separated by approximately 20 m. Elevated time-integrated PM(2.5) samplers (n=4/plot) were hung atop approximately 30 ft poles at positions within the interior of each of the plots. Real-time PM(2.5) and CO data were collected at downwind locations on the perimeter of each plot. Time-integrated perimeter 12-h PM(2.5) concentrations in the non-chipped plot (AVG 519.9 microg/m(3), SD 238.8 microg/m(3)) were significantly higher (1-tail P-value 0.01) than those at the chipped plot (AVG 198.1 microg/m(3), SD 71.6 microg/m(3)). Similarly, interior time-integrated 8-h PM(2.5) concentrations in the non-chipped plot (AVG 773.4 microg/m(3), SD 321.8 microg/m(3)) were moderately higher (1-tail P-value 0.06) than those at the chipped plot (AVG 460.3 microg/m(3), SD 147.3 microg/m(3)). Real-time PM(2.5) and CO data measured at a position in the chipped plot were uniformly lower than those observed at the same position in the non-chipped plot over the same time period. These results demonstrate that smoke exposures resulting from burned chipped plots are considerably lower than from burned non-chipped plots. These findings have potentially important implications for both firefighters working prescribed burnings at chipped vs. non-chipped sites, as well as nearby communities who may be impacted from smoke traveling downwind from these sights. PMID:16736059

Naeher, Luke P; Achtemeier, Gary L; Glitzenstein, Jeff S; Streng, Donna R; Macintosh, David



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.



The Size and Distribution of Midbrain Dopaminergic Populations are Permanently Altered by Perinatal Glucocorticoid Exposure in a Sex Region and Time-Specific Manner  

Microsoft Academic Search

Central dopaminergic (DA) systems appear to be particularly vulnerable to disruption by exposure to stressors in early life, but the underlying mechanisms are poorly understood. As endogenous glucocorticoids (GCs) are implicated in other aspects of neurobiological programming, this study aimed to characterize the effects of perinatal GC exposure on the cytoarchitecture of DA populations in the substantia nigra pars compacta

Simon McArthur; Emily McHale; Glenda E Gillies



Human exposure to styrene  

Microsoft Academic Search

An industrial hygiene study of 10 glassfiber reinforced polyester plants (including 90 workers) was undertaken to investigate the styrene exposure in this industry and to estimate biological limit values (BLV's) for the urinary metabolites of styrene: mandelic (MA) and phenylglyoxylic acids (PGA). Time weighted average (TWA) styrene exposures were found ranging from 2 to 200 ppm. The urinary elimination of

Michel P. Guillemin; Daniel Bauer; Brigitte Martin; Alfio Marazzi




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...


A tiered approach combining the short time exposure (STE) test and the bovine corneal opacity and permeability (BCOP) assay for predicting eye irritation potential of chemicals.  


For the evaluation of eye irritation, one in vitro alternative test may not completely replace the Draize test. Therefore, a tiered approach combining several in vitro assays, including cytotoxicity assays, is proposed in order to estimate the eye irritation potential of a wide range of chemical classes. The Short Time Exposure (STE) test, a relatively newer alternative eye irritation test, involves exposing Statens seruminstitut rabbit cornea (SIRC) cells for 5 min to two concentrations (5% and 0.05%) of test material. In the present study, we examined the predictive capacity of a tiered approach analyzing the results from the STE test and then the results of the bovine corneal opacity and permeability (BCOP) assay for assessing globally harmonized system (GHS) eye irritation rankings of various chemicals. The accuracy of predicting the GHS rankings was slightly improved when the tiered approach combination of STE test and BCOP assay was used compared to when the STE test irritation rank classification was used alone. Moreover, the under prediction rate was substantially improved when this tiered approach was used. From these results, the tiered approach of combining the data analysis of the STE test and BCOP assay might be a promising alternative eye irritation test strategy. PMID:22467017

Hayashi, Kazuhiko; Mori, Taeko; Abo, Takayuki; Koike, Mirei; Takahashi, Yutaka; Sakaguchi, Hitoshi; Nishiyama, Naohiro



The Relative Timing of Exposure to Phagocytosable Particulates and to Osteoclastogenic Cytokines Is Critically Important in the Determination of Myeloid Cell Fate  

PubMed Central

During granulomatous inflammatory reactions, myeloid cells can differentiate into activated phagocytic macrophages, wound-healing macrophages, foreign body giant cells, and bone-resorbing osteoclasts. Although it is appreciated that a variety of stimuli, including cytokines, cell–matrix interactions, and challenge with foreign materials can influence myeloid cell fate, little is known of how these signals integrate during this process. In this study, we have investigated the cross talk between receptor activator of NF-?B ligand (RANKL)-induced osteoclastogenesis and particle phagocytosis-induced activation of human monocytes. Understanding interconnected signals is of particular importance to disorders, such as periprosthetic osteolysis, in which granulomatous inflammation is initiated by particle phagocytosis in proximity to bone and leads to inflammatory bone loss. Using cell-based osteoclastogenesis and phagocytosis assays together with expression analysis of key regulators of osteoclastogenesis, we show in this study that phagocytosis of disease-relevant particles inhibits RANKL-mediated osteoclastogenesis of human monocytes. Mechanistically, phagocytosis mediates this effect by downregulation of RANK and c-Fms, the receptors for the essential osteoclastogenic cytokines RANKL and M-CSF. RANKL pretreatment of monocytes generates preosteoclasts that are resistant to RANK downregulation and committed to osteoclast formation, even though they retain phagocytic activity. Thus, the relative timing of exposure to phagocytosable particulates and to osteoclastogenic cytokines is critically important in the determination of myeloid cell fate.

James, Douglas E.; Nestor, Bryan J.; Sculco, Thomas P.; Ivashkiv, Lionel B.; Ross, F. Patrick; Goldring, Steven R.; Purdue, P. Edward



Stomatal response and leaf injury of Pisum sativum L. with SO/sub 2/ and O/sub 3/ exposures. II. Influence of moisture stress and time of exposure  

SciTech Connect

Stomatal response during exposure to SO/sub 2/ and O/sub 3/ and subsequent leaf injury were examined in plants of Pisum sativum L. Alsweet grown in a peat-vermiculite medium in controlled environment chambers. Plants developing under moisture stress, induced by drying the medium to 50% of field capacity, exhibited greater stomatal closure during exposures and less than one-fourth the necrosis compared to plants developing in a medium maintained at field capacity. Plants under moisture stress had only a slightly more negative plant water potential (approx. = 4.0 bars) than at field capacity (approx. = 3.4 bars). Plants exposed to pollutants for 2 hours near the beginning or end of a 16-hour light period had greater stomatal closure during exposures and less leaf necrosis than plants exposed during the middle of the light period.

Olszyk, D.M.; Tibbitts, T.W.



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



Derivation of 2,3,7,8TCDD toxic equivalence factors (TEFs) for selected dioxins, furans and PCBs with rainbow trout and rat liver cell lines and the influence of exposure time  

Microsoft Academic Search

The effect of exposure time on the induction of 7-ethoxyresorufin O-deethylase (EROD) by 2,3,7,8-tetrachlorobenzo-p-dioxin (TCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), and 3,3?,4,4?-tetrachlorobiphenyl (PCB 77) was examined in two liver cell lines: rainbow trout RTL-W1 and rat H4IIE. In RTL-W1, exposure time had no effect on induction EC50s and derivation of TCDD- toxic equivalency factors (TEFs). In H4IIE, EC50s for TCDD also were unchanged.

Janine H. Clemons; D. George Dixon; Niels C. Bols



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



Cosmogenic isotope ( 36Cl) surface exposure dating of the Norber erratics, Yorkshire Dales: Further constraints on the timing of the LGM deglaciation in Britain  

Microsoft Academic Search

Cosmogenic isotope (36Cl) surface exposure dating of four of the erratic boulders at Norber in the Yorkshire Dales National Park, northwest England, yielded mean ages of ?22.2±2.0ka BP and ?18.0±1.6ka BP for their emplacement. These two mean values derive from different 36Cl production rates used for exposure age calculation. The ages are uncorrected for temporal variations in production rates and

Peter J. Vincent; Peter Wilson; Tom C. Lord; Christoph Schnabel; Klaus M. Wilcken



A spatially disaggregated time-series analysis of the short-term effects of particulate matter exposure on mortality in Chennai, India  

Microsoft Academic Search

The global burden of disease due to air pollution is concentrated in the rapidly developing counties of Asia, but a recent\\u000a meta-analysis found that relatively few studies on short-term exposure to air pollution and mortality have been performed\\u000a in these countries, including India. Local evidence on the effects of short-term exposures to air pollutants on mortality\\u000a and cardio-respiratory morbidity in

Kalpana Balakrishnan; Bhaswati Ganguli; Santu Ghosh; Sankar Sambandam; Sugata Sen Roy; Aditya Chatterjee



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...


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.  


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 that 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. PMID:23195754

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



Biomarkers of pesticide exposure.  


Incorporation of biomarkers in studies of occupational exposure hazards is now recognized as a highly useful adjunct to the surrogate measures employed in the past, for example, time worked, ambient air data, interview responses. Application to studies of workers potentially exposed to pesticides has barely begun and provides many challenges to chemist/epidemiologist teams. This review indicates several excellent studies employing multiple-exposure measures to document the validity of specific biomarkers for particular exposure situations. In general, exposure reflected by urinary assays of specific pesticides is a low percentage of that indicated by dermal or breathing zone measures. Markers for many of the pesticides in current usage have yet to be developed and validated, and information on population variability is generally lacking for existing markers. The challenge provided by the complexity of multiple, and often unknown, exposures to individuals in pesticide environments has begun to be addressed employing cytogenetic or urinary measures that attempt to integrate these complex exposures. The lack of data regarding sensitivity and specificity of biomarkers, especially in complex exposure situations, is a major problem that perhaps will best be addressed by studies combining nonspecific measures with specific ones, utilizing stored sample banks created for that purpose. Expanding the repertoire of available biomarkers of pesticide exposure and employing multiple ones in well-designed study protocols will provide critical tools in the evaluation of pesticide safety and design of appropriate measures to minimize adverse exposures. Ironically, one of the problems that biological markers of exposure can help overcome, reliance on poorly measured ambient exposure data, hampers the evaluation of the markers themselves. Therefore, the combination of in vitro, animal, and human data will give the best picture of a marker's performance. (Wilcosky 1990). PMID:1410687

Brewster, M A; Hulka, B S; Lavy, T L



Environmental Exposures and Development  

PubMed Central

Structured Abstract Purpose of Review Summarize recent studies exploring the relationship between paternal and maternal environmental exposures to chemicals before, at the time of and after conception to adverse developmental outcomes including; preterm birth, death, structural and functional abnormalities and growth restriction. Recent Findings Recent studies have demonstrated that human pregnancy and development is vulnerable to environmental exposures of the father and mother to chemical, biological and physical agents. Exposures associated with adverse developmental outcomes include; air and water pollution, chemicals in foods, occupational exposures, agricultural chemicals, metals, persistent and volatile organics. Developmental endpoints which are linked with these exposures include; growth restriction, functional abnormalities, structural abnormalities, preterm delivery and death. Despite this general understanding we still have incomplete knowledge concerning most exposures and the biological interactions responsible for impaired development and preterm delivery. Summary While single genes and individual chemical exposures are responsible for some instances of adverse pregnancy outcome or developmental disease, gene-environment interactions are responsible for the majority. These gene-environment interactions may occur in the father, mother, placenta or fetus suggesting that critical attention be given to maternal and paternal exposures and gene expression as they relate to the mode of action of the putative developmental toxicant both prior to and during pregnancy.

Mattison, Donald R.



Growth factor plus preemptive ('just-in-time') plerixafor successfully mobilizes hematopoietic stem cells in multiple myeloma patients despite prior lenalidomide exposure.  


Lenalidomide is associated with suboptimal autologous hematopoietic stem cell (AHSC) mobilization. We hypothesized that growth factor plus preemptive plerixafor is an effective strategy for AHSC mobilization in multiple myeloma (MM) despite prior exposure to lenalidomide. We retrospectively reviewed patient characteristics and mobilization outcomes of 89 consecutive MM patients undergoing first mobilization with filgrastim or pegfilgrastim +/- preemptive plerixafor using a previously validated algorithm based on day 4 peripheral blood CD34+ cell count (PB-CD34+) and mobilization target. Outcomes were analyzed according to the extent of prior exposure to lenalidomide: no prior exposure (group A, n=40), 1- 4 cycles (group B, n=30) and >4 cycles (group C, n=19). Multivariate analysis yielded only age and number of cycles of lenalidomide as negatively associated, and mobilization with pegfilgrastim as positively associated with higher PB-CD34+. Only 45% of patients in group A required plerixafor vs 63% in groups B and 84% in C, P=0.01. A higher proportion of patients in group A (100%) met the mobilization target than in groups B (90%) or C (79%), P=0.008. All patients yielded at least 2 × 10(6)?CD34+/kg. Growth factor mobilization with preemptive plerixafor is an adequate upfront mobilization strategy for MM patients regardless of prior exposure to lenalidomide. PMID:22484324

Costa, L J; Abbas, J; Hogan, K R; Kramer, C; McDonald, K; Butcher, C D; Littleton, A; Shoptaw, K; Kang, Y; Stuart, R K



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



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...


Mobile Internet Monetization: A Methodology to Monitor in Real Time the Cellular Subscriber Transactional Itinerary, from Mobile Advertising Exposure to Actual Purchase  

Microsoft Academic Search

The deployment of broadband mobile networks and the surging sales of Smartphones, tablets and 3G data keys are boosting mobile Internet usage among much wider audiences. Obtaining reliable information on mobile Internet traffic, online user behavior and mobile advertising exposure has become critical for the industry, notably the telecom and media sectors. The Network Intelligence Solution (NIS) is a new

Gerard Hermet; Jacques Combet



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.



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


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



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.



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



NOTE: Modeling time variation of blood temperature in a bioheat equation and its application to temperature analysis due to RF exposure  

Microsoft Academic Search

The present study discusses a scheme to take into account core temperature variation in a well-known bioheat equation. First, the limitation in conventional modeling of the bioheat equation was investigated for a problem in which the whole-body phantom should be taken into account. Then, schemes for varying body-core temperature in the bioheat equation were discussed for radio-frequency exposures. The computational

Akimasa Hirata; Osamu Fujiwara



A novel waveguide-based radio frequency\\/microwave exposure system for studying nonthermal effects on neurotransmitter Release-finite-difference time-domain modeling  

Microsoft Academic Search

A research effort is underway to identify specific radio frequency\\/microwave parameters in the frequency range 0.75-1.12 GHz that can produce nonthermal effects on the release of catecholamines from cultured bovine adrenal medullary chromaffin cells, an established in vitro model of neural-type cells. A well-characterized exposure system is crucial for interpreting the biological outcomes of experiments. This paper describes a novel

Todd Hagan; Indira Chatterjee; Dana McPherson; Gale L. Craviso



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  

Microsoft Academic Search

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 5min 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.

Yutaka Takahashi; Kazuhiko Hayashi; Takayuki Abo; Mirei Koike; Hitoshi Sakaguchi; Naohiro Nishiyama



Inhaled cationic amphiphilic drug-induced pulmonary phospholipidosis in rats and dogs: time-course and dose-response of biomarkers of exposure and effect.  


This study compares the pulmonary response to an inhaled highly soluble hydrochloride (CAD-HCl) with a low soluble sulphate salt (CAD-SO4) of a dicationic amphiphilic drug (CAD). These salts are known to accumulate in the lung. The bioavailability through gastrointestinal uptake is poor. Wistar rats and beagle dogs received repeated 1 h/day inhalation exposures over 1-4 weeks. The focus of this analysis is to appraise the correlation of markers of effects related to pulmonary phospholipidosis and cytotoxicity relative to the concentration of CAD in the lung tissue, alveolar macrophages and serum. Rats and dogs are known to experience remarkable differences in their respiratory minute volumes and respiratory patterns. In order to facilitate dosimetric comparisons, identical exposure paradigms and methodological procedures were selected. Over a wide range of cumulative dosages, the CADs bound to lung tissue and cells in bronchoalveolar lavage (BAL) paralleled, whilst no clear association existed in terms of plasma concentrations. This suggests that analysis of the fractional loading of BAL-cells (mainly alveolar macrophages) with CAD or CAD-surfactant complexes is amenable to monitor the accumulation of CADs in the lung. In terms of the comparative phospholipidosis-inducing potency, the CAD-HCl was more potent as compared to CAD-SO4. Following dosimetric adjustments, rats and dogs appeared to be equally susceptible to phospholipidosis. In summary, when exposed to equivalent concentrations of CADs, dogs did not demonstrate a markedly different susceptibility than rats. With regard to the relative intensity of changes, the increase of phospholipids in BAL-fluid and especially BAL-cells correlated with the cumulative exposure dose. Thus, with regard to probing the extent of CAD-induced 'overloading' of alveolar macrophages pharmacokinetic determinations in BAL-cells are considered superior to determinations in plasma. Additional advantages of using the alveolar macrophage as denominator to normalize pulmonary drug concentrations include comparisons across species, and exposure regimens are feasible based on almost readily available endpoints in both pre-clinical and selected clinical studies. PMID:15590122

Pauluhn, Jürgen



NOTE: Modeling time variation of blood temperature in a bioheat equation and its application to temperature analysis due to RF exposure  

NASA Astrophysics Data System (ADS)

The present study discusses a scheme to take into account core temperature variation in a well-known bioheat equation. First, the limitation in conventional modeling of the bioheat equation was investigated for a problem in which the whole-body phantom should be taken into account. Then, schemes for varying body-core temperature in the bioheat equation were discussed for radio-frequency exposures. The computational uncertainty in the core temperature elevation was found to be reasonable when a proper scheme for computing the net rate of heat acquisition by blood from body tissue was introduced.

Hirata, Akimasa; Fujiwara, Osamu



Mapping occupational heat exposure and effects in South-East Asia: ongoing time trends 1980-2011 and future estimates to 2050.  


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



[Radiodiagnostic evaluation in osseointegrated dental implants].  


The Authors examine the various radiological techniques indispensable to pre- and postsurgical evaluation in endosseous dental implantology. Of each technique the choice criteria and diagnostic potentialities are suggested. PMID:1925767

Andreoli, G L; Di Maggio, A; Sanna, C


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


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



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)



Contamination of polychlorinated biphenyls and organochlorine pesticides in breast milk in Korea: Time-course variation, influencing factors, and exposure assessment.  


Breast milk is a noninvasive specimen to assess maternal and infant exposure to polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). In this study, 206 breast milk samples were collected from 87 participants during lactation, at <7, 15, 30, or 90days postpartum in four cities in Korea. The total concentrations of PCBs (?PCB) and OCPs (?OCP) ranged from exposure of Korean infants to chlordanes via breast milk had a potential health risk which deserves further investigation. PMID:24112654

Lee, Sunggyu; Kim, Sunmi; Lee, Hyun-Kyung; Lee, In-Seok; Park, Jeongim; Kim, Hai-Joong; Lee, Jeong Jae; Choi, Gyuyeon; Choi, Sooran; Kim, Sungjoo; Kim, Su Young; Choi, Kyungho; Kim, Sungkyoon; Moon, Hyo-Bang



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



Techniques for Predicting Fallout Radiation Exposures from Exposure and Exposure Rate Measurements.  

NASA Astrophysics Data System (ADS)

Techniques have been derived for predicting future exposures to fallout radiations from exposure rate measurements obtained soon after the cessation of fallout due to one or more nuclear detonations. Computerized and manual techniques have been derived for predicting exposures within about 20% - 40% error, depending on the time interval of the exposure and the time of prediction. Both systematic and random sources of error have been considered. The computer technique proposed is based on an iterative, weighted least squares fit to early exposure rate measurements. The manual technique proposed is based on the average half-life of the fallout mixture at the time of prediction, as characterized by two single exposure rate measurements. Rules of thumb are proposed to determine when after fallout cessation special exposure prediction techniques would no longer be needed. The proposed techniques are based on exposure rate measurements one would obtain in either unsheltered or protected locations. No information is required on the number or timing of detonations contributing fallout at the location. The only reference times needed are the start of exposure accumulation and the time of the last major exposure rate peak, both which could be determined from exposure rate measurements. The many variables that affect the accuracy and validity of exposure prediction techniques are researched and discussed in this study, including fractionation of fallout due to selective condensation of fallout elements, the type of fissile and fissionable material employed in the weapon, neutron activation of materials in or near the weapon, weathering of fallout particles, shielding of fallout gamma radiation, the mixture of different aged fallout from multiple, non-simultaneous detonations, and other characteristics of weapon design and deployment, such as the energy fluence of neutrons emitted during the detonation.

French, Clayton Sumner, Jr.


Dynamic effects of free chlorine concentration, organic load, and exposure time on the inactivation of Salmonella, Escherichia coli O157:H7, and non-O157 Shiga toxin-producing E. coli.  


This study evaluated the dynamic effects of free-chlorine (FC) concentration, contact time, and organic load on the inactivation of Salmonella, Escherichia coli O157:H7, and non-O157 Shiga toxin-producing E. coli (STEC) in suspension. Bacterial cells from four strains each of Salmonella, E. coli O157:H7, and non-O157 STEC were inoculated separately or as a multistrain cocktail into solutions with varying FC concentrations. Lettuce or tomato extract was used to simulate the organic matter present during commercial fresh and fresh-cut produce wash operations. After exposure to FC for various lengths of time, the bacterial survival and water-quality changes were determined. In the absence of organic matter in a wash solution, pathogen inactivation is primarily a function of initial FC concentration (P < 0.0001), exposure time (P < 0.0001), and pathogen strains (P < 0.0001). In general, an over 4.5-log CFU/ml pathogen reduction was found after exposure to >0.5 mg/liter FC for over 30 s, or to >1.0 mg/liter FC for over 5 s. When the combination of FC concentration and contact time were less than or equal to the above conditions, survival of pathogens was strain dependant and ranked as: Salmonella > E. coli O157:H7 > non-O157 STEC. When organic matter was present in the wash solution, pathogen inactivation efficacy was specifically dependent on the residual FC concentration, which directly relates to both the initial FC concentration and the organic load. Prevention of pathogen survival in chlorinated produce wash solutions can be achieved by maintaining sufficient FC concentration and reducing the accumulation of organic matter. PMID:23462074

Shen, Cangliang; Luo, Yaguang; Nou, Xiangwu; Wang, Qin; Millner, Patricia



Concentration- and time-dependent genomic changes in the mouse urinary bladder following exposure to arsenate in drinking water for up to 12 weeks.  


Inorganic arsenic (As(i)) is a known human bladder carcinogen. The objective of this study was to examine the concentration dependence of the genomic response to As(i) in the urinary bladders of mice. C57BL/6J mice were exposed for 1 or 12 weeks to arsenate in drinking water at concentrations of 0.5, 2, 10, and 50 mg As/l. Urinary bladders were analyzed using gene expression microarrays. A consistent reversal was observed in the direction of gene expression change: from predominantly decreased expression at 1 week to predominantly increased expression at 12 weeks. These results are consistent with evidence from in vitro studies of an acute adaptive response that is suppressed on longer exposure due to downregulation of Fos. Pathways with the highest enrichment in gene expression changes were associated with epithelial-to-mesenchymal transition, inflammation, and proliferation. Benchmark dose (BMD) analysis determined that the lowest median BMD values for pathways were above 5 mg As/l, despite the fact that pathway enrichment was observed at the 0.5 mg As/l exposure concentration. This disparity may result from the nonmonotonic nature of the concentration-responses for the expression changes of a number of genes, as evidenced by the much fewer gene expression changes at 2 mg As/l compared with lower or higher concentrations. Pathway categories with concentration-related gene expression changes included cellular morphogenesis, inflammation, apoptosis/survival, cell cycle control, and DNA damage response. The results of this study provide evidence of a concentration-dependent transition in the mode of action for the subchronic effects of As(i) in mouse bladder cells in the vicinity of 2 mg As(i)/l. PMID:21795629

Clewell, H J; Thomas, R S; Kenyon, E M; Hughes, M F; Adair, B M; Gentry, P R; Yager, J W



40Ar/39Ar dating and cosmic-ray exposure time of desert meteorites: Dhofar 300 and Dhofar 007 eucrites and anomalous achondrite NWA 011  

NASA Astrophysics Data System (ADS)

We performed high-resolution 40Ar-39Ar dating of mineral separates and whole-rock samples from the desert meteorites Dhofar 300, Dhofar 007, and Northwest Africa (NWA) 011. The chronological information of all samples is dominated by plagioclase of varying grain size. The last total reset age of the eucrites Dhofar 300 and Dhofar 007 is 3.9 ± 0.1 Ga, coeval with the intense cratering period on the Moon. Some large plagioclase grains of Dhofar 007 possibly inherited Ar from a 4.5 Ga event characteristic for other cumulate eucrites. Due to disturbances of the age spectrum of NWA 011, only an estimate of 3.2-3.9 Ga can be given for its last total reset age. Secondary events causing partial 40Ar loss ?3.4 Ga ago are indicated by all age spectra. Furthermore, Ar extractions from distinct low temperature phases define apparent isochrons for all samples. These isochron ages are chronologically irrelevant and most probably caused by desert alterations, in which radiogenic 40Ar and K from the meteorite and occasionally K induced by weathering are mixed, accompanied by incorporation of atmospheric Ar. Additional uptake of atmospheric Ar by the alteration phase(s) was observed during mineral separation (i.e., crushing and cleaning in ultrasonic baths). Consistent cosmic-ray exposure ages were obtained from plagioclase and pyroxene exposure age spectra of Dhofar 300 (25 ± 1 Ma) and Dhofar 007 (13 ± 1 Ma) using the mineral's specific target element chemistry and corresponding 38Ar production rates.

Korochantseva, Ekaterina V.; Trieloff, Mario; Buikin, Alexei I.; Hopp, Jens; Meyer, Hans-Peter



Exposure to Bioaerosols in Poultry Houses at Different Stages of Fattening; Use of Real-time PCR for Airborne Bacterial Quantification  

PubMed Central

Previous studies have demonstrated that poultry house workers are exposed to very high levels of organic dust and consequently have an increased prevalence of adverse respiratory symptoms. However, the influence of the age of broilers on bioaerosol concentrations has not been investigated. To evaluate the evolution of bioaerosol concentration during the fattening period, bioaerosol parameters (inhalable dust, endotoxin and bacteria) were measured in 12 poultry confinement buildings in Switzerland, at three different stages of the birds’ growth; samples of air taken from within the breathing zones of individual poultry house employees as they caught the chickens ready to be transported for slaughter were also analysed. Quantitative polymerase chain reaction (Q-PCR) was used to assess the quantity of total airborne bacteria and total airborne Staphylococcus species. Bioaerosol levels increased significantly during the fattening period of the chickens. During the task of catching mature birds, the mean inhalable dust concentration for a worker was 26 ± 1.9 mg m?3 and endotoxin concentration was 6198 ± 2.3 EU m?3 air, >6-fold higher than the Swiss occupational recommended value (1000 EU m?3). The mean exposure level of bird catchers to total bacteria and Staphylococcus species measured by Q-PCR is also very high, respectively, reaching values of 53 (±2.6) × 107 cells m?3 air and 62 (±1.9) × 106 m?3 air. It was concluded that in the absence of wearing protective breathing apparatus, chicken catchers in Switzerland risk exposure beyond recommended limits for all measured bioaerosol parameters. Moreover, the use of Q-PCR to estimate total and specific numbers of airborne bacteria is a promising tool for evaluating any modifications intended to improve the safety of current working practices.

Oppliger, Anne; Charriere, Nicole; Droz, Pierre-Olivier; Rinsoz, Thomas




Microsoft Academic Search

An exact surface integral derived from the Green's theorem in the time domain, combined with the finite-differences time-domain method (FDTD) is used to simulate an actual base-station antenna that illuminates a place where people can stand. Moreover, as large scattering objects can be in the surroundings, near the antenna and\\/or the person, high frequency techniques in the time domain are

L. Nonídez; M. Martínez; A. Martín; R. Villar



Real-Time and Integrated Measurement of Potential Human Exposure to Particle-Bound Polycyclic Aromatic Hydrocarbons (PAHs) from Aircraft Exhaust  

Microsoft Academic Search

We used real-time monitors and low-volume air samplers to measure the potential human expo- sure 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

Jeffrey W. Childers; Carlton L. Witherspoon; Leslie B. Smith; Joachim D. Pleil


Saline drinking water in broiler and Leghorn chicks and the effect in broilers of increasing levels and age at time of exposure  

PubMed Central

The purpose of this research was to assess the effect of increasing levels of salt and 5 g/L of salt (0.20% extra sodium) in the drinking water in broiler chickens at various ages up to five weeks of age and to compare the response of broiler chickens and White Leghorns to saline water (0.20% sodium). The effect was measured by the response of the right ventricle to pulmonary hypertension. The results indicated that broiler chickens under three weeks are more susceptible to saline water containing 0.20% sodium than those over three weeks of age, and that broilers given increasing levels of dietary salt may be more resistant to excess dietary salt than those that have had no previous exposure. The results also demonstrated that broiler chickens are more susceptible than White Leghorns to 0.20% extra dietary sodium in drinking water. We conclude that Leghorn chicks are more resistant to excess dietary sodium than broilers and that broilers become more resistant to saline water containing 0.20% sodium after three weeks of age. ImagesFigure 1.

Mirsalimi, S. Mehdi; Julian, Richard J.



Exposure chamber  


An exposure chamber includes an imperforate casing having a fluid inlet at the top and an outlet at the bottom. A single vertical series of imperforate trays is provided. Each tray is spaced on all sides from the chamber walls. Baffles adjacent some of the trays restrict and direct the flow to give partial flow back and forth across the chambers and downward flow past the lowermost pan adjacent a central plane of the chamber.

Moss, Owen R. (Kennewick, WA); Briant, James K. (Pasco, WA)



The effects of free chlorine concentration, organic load, and exposure time on the inactivation of Salmonella, Escherichia coli O157:H7 and non-O157 STEC  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study evaluated the effects of free chlorine (FC) concentration, contact time, and organic load on the inactivation of Salmonella, E. coli O157:H7, and non-O157 STEC in suspension. Four strains each of Salmonella, E. coli O157:H7, or non-O157 STEC cells were inoculated separately or as a multi-...


Predicting Personal Nitrogen Dioxide Exposure in an Elderly Population: Integrating Residential Indoor and Outdoor Measurements, Fixed-Site Ambient Pollution Concentrations, Modeled Pollutant Levels, and Time–Activity Patterns  

Microsoft Academic Search

Predicting chronic exposure to air pollution at the intra-urban scale has been recognized as a priority area of research for environmental epidemiology. Exposure assessment models attempt to predict and proxy for individuals' personal exposure to ambient air pollution, and there are no studies to date that explicitly attempt to compare and cross-validate personal exposure concentrations with pollutants modeled at the

Talar Sahsuvaroglu; Jason G. Su; Jeffery Brook; Richard Burnett; Mark Loeb; Michael Jerrett



Wide beam reconstruction for half-dose or half-time cardiac gated SPECT acquisitions: optimization of resources and reduction in radiation exposure  

Microsoft Academic Search

Purpose  A new iterative reconstruction algorithm (WBR™) has been recently proposed for cardiac single photon emission computed tomography\\u000a (SPECT). The WBR™ technology is designed to reduce noise, improving lesion identification without affecting the image resolution,\\u000a allowing SPECT studies with reduced count statistic. This allows for either half-time (HT) or half-dose (HD) cardiac SPECT,\\u000a with image quality and quantitative data comparable to

Claudio Marcassa; Riccardo Campini; Orazio Zoccarato; Paolo Calza



Mechanism of ?-Cr precipitation and crystallographic relationships between ?-Cr and ? phases in Inconel 718 alloy after long-time thermal exposure  

Microsoft Academic Search

To study the precipitation mechanism of ?-Cr phase in Inconel 718 alloy, the samples after long-time aging at 650 and 677°C\\u000a were examined by microstructural observations and chemical phase analysis methods. Combining the thermodynamics and kinetics\\u000a calculation results, ?-Cr always precipitates in the vicinity of ? phase, because ? phase rejects Cr into the ?-matrix when\\u000a growing. The selected area

Zhong-nan Bi; Jian-xin Dong; Mai-cang Zhang; Lei Zheng; Xi-shan Xie



Tryptophan dynamics in the exploration of micro-conformational changes of refolded ?-lactoglobulin after thermal exposure: a steady state and time-resolved fluorescence approach.  


Refolding intermediates of proteins, including molten globules, are likely to undergo dynamic conformational transitions. In this work, thermal unfolding and refolding of bovine ?-lactoglobulin (?-lg) have been revisited to encounter such intermediate states. Lower thermal range (< 80°C) was selected to avoid irreversible aggregate formation. The gross kinetic refolding as monitored with the fluorophore, Trp19, was likely to be reversible but alteration in time resolved fluorescence parameters ruled out the possibility of micro-structural reversibility for the refolded partner. Time resolved fluorescence showed that the refolded protein still lacks some intact native conformation. Far-UV CD signals lack the signature of any secondary structural distortion in global structural context whereas near-UV CD signals were strongly indicative of perturbation in micro-structure surrounding the aromatic moieties which hardly revives after cooling. Steady state anisotropy results showed successfully the break-down of dimer to monomer form of ?-lg within 50°C temperature range and augmentation in anisotropy up on further thermal stress reflected the reorganization of tryptophan residues into more restricted and rigid micro-environment as well as irreversible disulfide-linked dimer formation. Reliability of conformational reversibility in the thermal unfolding-refolding is still enigmatic on micro and global structural perspectives. Intermediate state prior to the completion of refolding of thermally exposed ?-lg was identified through fluorescence studies. PMID:22342029

Halder, Umesh C; Chakraborty, Jishnu; Das, Niloy; Bose, Sayantan



Example Exposure Scenarios.  

National Technical Information Service (NTIS)

Exposure scenarios are a tool to help the assessor develop estimates of exposure, dose, and risk. An exposure scenario generally includes facts, data, assumptions, inferences, and sometimes professional judgment about how the exposure takes place. The hum...



Exposure guidelines for magnetic fields  

SciTech Connect

The powerful magnetic fields produced by a controlled fusion experiment at Lawrence Livermore National Laboratory (LLNL) necessitated the development of personnel-exposure guidelines for steady magnetic fields. A literature search and conversations with active researchers showed that it is currently possible to develop preliminary exposure guidelines for steady magnetic fields. An overview of the results of past research into the bioeffects of magnetic fields was compiled, along with a discussion of hazards that may be encountered by people with sickle-cell anemia or medical electronic and prosthetic implants. The LLNL steady magnetic-field exposure guidelines along with a review of developments concerning the safety of time-varying fields were also presented in this compilation. Guidelines developed elsewhere for time varying fields were also given. Further research is needed to develop exposure standards for both steady or time-varying fields.

Miller, G.



Evaluation of emotional behaviors in young offspring of C57BL/6J mice after gestational and/or perinatal exposure to nicotine in six different time-windows.  


Nicotine replacement treatments are being alternatively applied as an aid to smoking cessation during pregnancy. However, the effects of nicotine exposed at the prenatal stage on the emotional behaviors in offspring are not well understood due to the lack of systematic investigations. The current study has therefore initially aimed to evaluate emotional behaviors in young mouse offspring (postnatal day 28-36) which experienced gestational and/or perinatal nicotine exposure (GPNE) in six different time-windows. Pregnant C57BL/6J mice were exposed to nicotine via sweetened (2% sucrose) drinking water during 6 different time-windows including gestational day 0-day 13 (G0-G13), G14-perinatal day 0 (P0), G0-P0, G14-P7, G0-P7, and P0-P7. During P28-P36 days, both male and female offspring were given a battery of behavioral tests including light and dark box test, marble burying behavior test, novelty-suppressed feeding test, sociability and social novelty preference test, social avoidance tube test, and elevated plus maze test. GPNE during G0-P0, G14-P0, G14-P7, and G0-P7 induced abnormal behaviors in male and female offspring to different extent. Results indicated that nicotine at any time points of gestational and/or perinatal period impairs emotional behaviors in offspring, and suggested certain time-windows for further neurochemical or molecular studies in relation with GPNE-induced emotional abnormalities. PMID:23142610

Alkam, Tursun; Kim, Hyoung-Chun; Hiramatsu, Masayuki; Mamiya, Takayoshi; Aoyama, Yuki; Nitta, Atsumi; Yamada, Kiyofumi; Nabeshima, Toshitaka



Personal carbon monoxide exposure in Helsinki, Finland  

NASA Astrophysics Data System (ADS)

Personal exposure concentrations of carbon monoxide (CO) were measured for the adult urban population of Helsinki, Finland, as part of the multi-centre European EXPOLIS study. The arithmetic mean of the 48 h average personal CO exposure concentration was 1.3 mg m -3 for participants not exposed to environmental tobacco smoke (ETS) and 1.6 mg m -3 for those exposed to ETS at any time and in any microenvironment. The maximum 8 and 1 h exposure values were 2.0 and 2.6 mg m -3, and 4.3 and 5.7 mg m -3, respectively. As tobacco smoke is one of the major sources of CO, therefore the personal mean exposures of ETS participants were higher than the non-ETS participants for all averaging times. The long- and short-term personal exposures were higher in winter than in summer for all participants. In order to analyse in more detail the correlation between the time-activity patterns and exposure levels, cluster analysis was performed using 24 h personal exposure profiles of 1 h moving averages. The results showed clearly that the major source of CO for non-ETS exposed participants are traffic emissions. The majority of the diurnal exposure profiles showed two notable exposure peaks corresponding to the morning and evening traffic rush hours. The time spent in street traffic was the most relevant factor for describing the short-term personal exposures. The more time was spent commuting by car the higher were the exposures. The long-term exposure levels were linked both to the time spent commuting and home location. People living in low-traffic suburban areas and working in downtown spent more time commuting and ended up experiencing similar long-term exposure levels than people who lived in heavy-traffic downtown areas, but spent little time commuting. For ETS exposed participants the personal exposure profiles were dominated by both tobacco smoke and traffic emissions.

Scotto di Marco, Greta; Kephalopoulos, Stylianos; Ruuskanen, Juhani; Jantunen, Matti


Response of a diuron-degrading community to diuron exposure assessed by real-time quantitative PCR monitoring of phenylurea hydrolase A and B encoding genes.  


A real-time quantitative PCR method was developed to detect and quantify phenlylurea hydrolase genes' (puhA and puhB) sequences from environmental DNA samples to assess diuron-degrading genetic potential in some soil and sediment microbial communities. In the soil communities, mineralization rates (determined with [ring-¹?C]-labeled diuron) were linked to diuron-degrading genetic potentials estimated from puhB number copies, which increased following repeated diuron treatments. In the sediment communities, mineralization potential did not depend solely on the quantity of puhB copies, underlining the need to assess gene expression. In the sediment samples, both puhB copy numbers and mineralization capacities were highly conditioned by whether or not diuron-treated soil was added. This points to transfers of degradative potential from soils to sediments. No puhA gene was detected in soil and sediment DNA extracts. Moreover, some sediments exhibited high diuron mineralization potential even though puhB genes were not detected, suggesting the existence of alternative diuron degradation pathways. PMID:22854895

Pesce, Stéphane; Beguet, Jérémie; Rouard, Nadine; Devers-Lamrani, Marion; Martin-Laurent, Fabrice



The influence of age at time of exposure to sup 226 Ra or sup 239 Pu on distribution, retention, postinjection survival, and tumor induction in beagle dogs  

SciTech Connect

The influence of age at injection of 226Ra or 239Pu on skeletal deposition and local distribution, the pattern of bone tumor formation, and postinjection survival was assessed in parallel short-term studies of mechanisms and lifetime toxicity. Beagles received a single intravenous injection of 226Ra or 239Pu at 3 months (juveniles), 17-19 months (young adults) or 60 months (mature). Data from short-term studies of mechanisms and dosimetry and from one dosage level of each of the toxicity experiments were compared. Skeletal growth and turnover produced differential initial deposition and distribution patterns typical for each age group. At 1 week after injection, skeletal retention of 226Ra or 239Pu was 68 and 68%, respectively, in the juveniles, 32 and 46% in the young adults, and 31 and 43% in the mature dogs. Comparing individual bones in the juveniles, gradients in the concentration of 239Pu were small since all bones were actively growing, but substantial gradients, corresponding to centers of ossification, were present within individual bones. In other age groups, local concentration gradients were less pronounced, but much larger differences were present among the various bones. In the toxicity study all animals injected with either 41 kBq 226Ra/kg or 11 kBq 239Pu/kg have died. The cumulative average skeletal doses to the presumed time of start of tumor growth (1 year before death) were 25 and 4 Gy, respectively, for the juveniles, 22 and 5 Gy for the young adults, and 15 and 4 Gy for the mature dogs. The highest bone tumor incidence was seen in the young adult groups. Differences were observed in location of bone tumors between dogs in the same age group given radium or plutonium and among age groups injected with either radionuclide, some of which could be explained by differences in local dose distributions.

Bruenger, F.W.; Lloyd, R.D.; Miller, S.C. (Univ. of Utah, Salt Lake City (USA))



A new electronic personal exposure meter for radon gas  

Microsoft Academic Search

A new electronic meter for personal radon exposures was developed and several prototypes were built. The exposure meter is optimized with respect to short-term (days) and long-term (>1y) measurements of indoor radon concentrations and personal radon exposure. The exposure meter records measured concentration levels in adjustable time intervals allowing a time resolved analysis.

F. L. Karinda; B. Haider; W. Rühm



Latency Models for Analyses of Protracted Exposures  

PubMed Central

The effect of an increment of exposure on disease risk may vary with time since exposure. If the pattern of temporal variation is simple (e.g., a peak then 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 paper 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.

Richardson, David B.



Exposure chamber  


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)



Regression models for the effects of exposure rate and cumulative exposure.  


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



Environmental exposure tracking sensor  

NASA Astrophysics Data System (ADS)

Cornerstone Research Group Inc. (CRG) has developed environmental exposure tracking (EET) sensors using shape memory polymer (SMP) to monitor the degradation of perishable items, such as munitions, medicines or foods, by measuring the cumulative exposure to temperature and moisture. SMPs are polymers whose qualities have been altered to give them dynamic shape "memory" properties. Under thermal or moisture stimuli, SMP exhibits a radical change from a rigid thermoset to a highly flexible, elastic state. The dynamic response of the SMP can be tailored to match the degradation profile of the perishable item. SMP-based EET sensors require no digital memory or internal power supply and provide the capability of inexpensive, long-term life cycle monitoring thermal and moisture exposure over time. In a Phase I and II SBIR effort with the Navy, CRG demonstrated the feasibility of SMP-based EET sensor with two material systems. These material systems required different activation stimuli, heat or water vapor pressure. CRG developed the ability to tailor these materials to customize the dynamic response to match various degradation profiles of munitions. CRG optimized and characterized the SMP formulations and sensor design configuration to develop a suite of data from which any degradation profile can be met. CRG's EET sensors are capable of monitoring temperatures from -30 °C to 260 °C. The prototypes monitor cumulative thermal exposure and provide real-time information in a visually readable or a remotely interrogated version. CRG is currently scaling up the manufacture of the sensors for munitions reliability applications with the Navy.

Havens, Teresa; Everhart, Joel; McFerran, Jace



Radiation Exposure  


Radiation is energy that travels in the form of waves or high-speed particles. It occurs naturally in sunlight. Man-made radiation is used in X-rays, nuclear weapons, nuclear power plants and cancer treatment. If you are exposed to small amounts of radiation over a long time, it raises ...


Effect of short- and long-term antibiotic exposure on the viability of Mycobacterium avium subsp. paratuberculosis as measured by propidium monoazide F57 real time quantitative PCR and culture.  


Mycobacterium avium subsp. paratuberculosis (MAP), the causative agent of paratuberculosis in ruminants, has a lipid-rich cell wall which facilitates its survival and persistence in the environment. This property of the organism is exploited when it is cultured as decontaminating agents and antibiotics are used to suppress the growth of contaminating microflora, but such treatments can also negatively affect the isolation of MAP itself. The objective of this study was to assess the effect of the 'VAN' antibiotics (vancomycin, amphotericin B and nalidixic acid) on the viability of MAP using a propidium monoazide real time quantitative PCR (PMA qPCR) and culture. Long-term (5 week) treatment with VAN antibiotics resulted in a larger decrease in bacterial numbers compared to short-term (3 day) exposure. The PMA qPCR assay indicated that 50 ?g/mL of vancomycin, 50 ?g/mL of nalidixic acid, and 200 ?g/mL of amphotericin B were 'threshold' concentrations, respectively, above which the decline in the viability of MAP was statistically significant. Using culture, these threshold concentrations were 100 ?g/mL of vancomycin, 50-100 ?g/mL of nalidixic acid, and 100 ?g/mL of amphotericin B, respectively. Given that the two methods were found to be comparable, the PMA qPCR is a potentially more convenient and effective alternative to culture in detecting MAP. PMID:22704136

Pribylova, Radka; Kubickova, Lucie; Babak, Vladimir; Pavlik, Ivo; Kralik, Petr



Exposure of the general population to gasoline.  


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. PMID:8020446

Akland, G G




Microsoft Academic Search

A quality industrial hygiene program must include the collection and management of workplace exposure information. For many industrial hygienists, however, exposure monitoring data are the only exposure information available. Often, there is no attempt to qualitatively estimate and document all known exposures because mechanisms for doing so are not widely available. Industrial hygienists and other occupational health professionals generally lack

Christopher L. Holzner; Richard B. Hirsh; Janet B. Perper



Medium wave exposure characterisation using exposure quotients.  


One of the aspects considered in the International Commission on Non-Ionizing Radiation Protection guidelines is that, in situations of simultaneous exposure to fields of different frequencies, exposure quotients for thermal and electrical stimulation effects should be examined. The aim of the present work was to analyse the electromagnetic radiation levels and exposure quotients for exposure to multiple-frequency sources in the vicinity of medium wave radio broadcasting antennas. The measurements were made with a spectrum analyser and a monopole antenna. Kriging interpolation was used to prepare contour maps and to estimate the levels in the towns and villages of the zone. The results showed that the exposure quotient criterion based on electrical stimulation effects to be more stringent than those based on thermal effects or power density levels. Improvement of dosimetry evaluations requires the spectral components of the radiation to be quantified, followed by application of the criteria for exposure to multiple-frequency sources. PMID:20159912

Paniagua, Jesús M; Rufo, Montaña; Jiménez, Antonio; Antolín, Alicia; Pinar, Iván



Survival attributable to an exposure  

PubMed Central

SUMMARY In the survival analysis context, when an intervention either reduces a harmful exposure or introduces a beneficial treatment, it seems useful to quantify the gain in survival attributable to the intervention as an alternative to the reduction in risk. To accomplish this we introduce two new concepts, the attributable survival and attributable survival time, and study their properties. Our analysis includes comparison with the attributable risk function as well as hazard-based alternatives. We also extend the setting to the case where the intervention takes place at discrete points in time, and may either eliminate exposure or introduce a beneficial treatment in only a proportion of the available group. This generalization accommodates the more realistic situation where the treatment or exposure is dynamic. We apply these methods to assess the effect of introducing highly active antiretroviral therapy for the treatment of clinical AIDS at the population level.

Cox, Christopher; Chu, Haitao; Munoz, Alvaro



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))




Microsoft Academic Search

Exposure to silica dust was studied in the grinding of castings in a steel foundry that used conventional personal sampling methods and new real-time sampling techniques developed for the identification of high-exposure tasks and tools. Approximately one-third of the personal samples exceeded the National Institute for Occupational Safety and Health recommended exposure limit for crystalline silica, a fraction similar to

Dennis OBrien; Phillip A. Froehlich; Michael G. Gressel; Ronald M. Hall; Nancy J. Clark; Patrick Bost; Thomas Fischbach




EPA Science Inventory

The average American spends an overwhelming portion of his/her time indoors. t is probable that the majority of ones exposure to pollutants will also occur indoors. ampling aerosols for risk assessment in the indoor environment present peculiar problems because of the relatively ...



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...



EPA Science Inventory

Anticipated results include the following. (1) We will estimate intake fraction (i.e., the fraction of emissions that are inhaled) for major source categories, over time, and by spatial location. Higher intake fraction indicates a greater exposure reduction per emission reduct...


Adolescent Exposure to Food Advertising on Television  

Microsoft Academic Search

Results: The results showed that among total nonprogram content time, food-related products accounted for roughly one fifth of advertising exposure. Excluding TV promotions and public service announcements, as a proportion of all product advertising, total food-related advertising made up 26% of advertised products viewed by adolescents. By race, the proportion of advertising exposure to food products was 14% greater for

Lisa M. Powell; Glen Szczypka; Frank J. Chaloupka



Occupational exposure to environmental tobacco smoke and health risk assessment.  

PubMed Central

This article addresses concepts of environmental tobacco smoke (ETS) exposure assessment relevant for health risk assessment based on human studies. We present issues that should be considered when selecting a method for ETS exposure assessment for the purposes of health risk assessment and review data on ETS exposure levels in the workplace and in home environments. Two types of estimates are needed for a quantitative risk assessment of the health effects resulting from occupational ETS exposure: (italic)a(/italic)) an unbiased estimate of the exposure-effect (or dose-response) relation between ETS and the health effect of interest, and (italic)b(/italic)) estimates of the distribution of ETS exposure in different workplaces. By combining the estimated exposure-effect relation with information on exposure distribution for a population of interest, we can calculate the proportions of disease cases attributable to occupational ETS exposure as well as the excess number of cases due to specified exposure conditions. Several dimensions of the exposure profile should be considered when assessing ETS exposure for estimating the exposure-effect relation, including the magnitude of exposure and the biologically relevant time specificity of exposure. The magnitude of exposure is determined by the ETS source strength, environmental factors modifying concentrations, and duration of exposure. Time specificity considerations include the latency period for each health outcome of interest, the time-exposure profile relevant for different disease mechanisms, and the sensitive age period with regard to health effects. The most appropriate indicator of ETS exposure depends on these factors and on the time period that can be assessed with different methods. Images Figure 1 Figure 3 Figure 4

Jaakkola, M S; Samet, J M



Exposure Analysis Modeling System  

EPA Science Inventory

The Exposure Analysis Modeling System (EXAMS) is an interactive software application for formulating aquatic ecosystem models and evaluating the fate, transport, and exposure concentrations of synthetic organic chemicals including pesticides, industrial materials, and leachates f...



EPA Science Inventory

Research collaborations between the National Health and Environmental Effects Research Laboratory (NHEERL) and the National Exposure Research Laboratory (NERL) centered on the development and application of exposure analysis tools in environmental epidemiology include the El Paso...


Dangers of Radiation Exposure  

NSDL National Science Digital Library

In the first part of the lesson, students calculate their yearly exposure rate to harmful high-energy radiation and cumulative effects over time. They then use the information to evaluate the various sources of radiation that are of greatest concern for them. In the second part of the lesson, students learn that spacecraft and other objects in space must be concerned with the same kinds of radiation to which humans are exposed. The MESSENGER spacecraft will orbit Mercury and be subjected to much more intense solar radiation than it would near Earth. Students discuss the notion that even though some of the radiation is needed to study the properties of the planet, too much of it can be quite damaging.

American Association for the Advancement of Science (AAAS;)



Swimmer Exposure Assessment Model  

EPA Science Inventory

The SWIMODEL is a screening tool for conducting an exposure assessment of pesticides found in indoor swimming pools and spas. The SWIMODEL uses well-accepted screening exposure assessment equations to calculate the total worst-case exposure for swimmers expressed as a mass-based...



EPA Science Inventory

This research constitutes the MCEARD base dietary exposure research program and is conducted to complement the NERL total human exposure program. The research builds on previous work to reduce the level of uncertainty in exposure assessment by improving NERL's ability to evaluat...



EPA Science Inventory

Human activity/uptake rate data are necessary to estimate potential human exposure and intake dose to environmental pollutants and to refine human exposure models. Personal exposure monitoring studies have demonstrated the critical role that activities play in explaining and pre...


Opioid Antagonist Impedes Exposure  

Microsoft Academic Search

Exposure is a rapid and effective treatment for simple phobias. This study tested the assumption that endorphin release may be involved in exposure to a feared situation. Thirty spider-phobic Ss underwent exposure to 17 phobic-related, graded performance tasks. Half the Ss were randomly assigned to naltrexone, an opioid antagonist, and half to a placebo. Measures of heart rate, blood pressure,

Thomas V. Merluzzi; C. Barr Taylor; Michael Boltwood; K. Gunnar Götestam



Opioid Antagonist Impedes Exposure.  

ERIC Educational Resources Information Center

|Thirty spider-phobic adults underwent exposure to 17 phobic-related, graded performance tests. Fifteen subjects were assigned to naltrexone, an opioid antagonist, and 15 were assigned to placebo. Naltrexone had a significant effect on exposure, with naltrexone subjects taking significantly longer to complete first 10 steps of exposure and with…

Merluzzi, Thomas V.; And Others



Biomarkers of environmental benzene exposure  

SciTech Connect

Environmental exposures to benzene result in increases in body burden that are reflected in various biomarkers of exposure, including benzene in exhaled breath, benzene in blood and urinary trans-trans-muconic acid and S-phenylmercapturic acid. A review of the literature indicates that these biomarkers can be used to distinguish populations with different levels of exposure (such as smokers from nonsmokers and occupationally exposed from environmentally exposed populations) and to determine differences in metabolism. Biomarkers in humans have shown that the percentage of benzene metabolized by the ring-opening pathway is greater at environmental exposures than that at higher occupational exposures, a trend similar to that found in animal studies. This suggests that the dose-response curve is nonlinear; that potential different metabolic mechanisms exist at high and low doses; and that the validity of a linear extrapolation of adverse effects measured at high doses to a population exposed to lower, environmental levels of benzene is uncertain. Time-series measurements of the biomarker, exhaled breath, were used to evaluate a physiologically based pharmacokinetic (PBPK) model. Biases were identified between the PBPK model predictions and experimental data that were adequately described using an empirical compartmental model. It is suggested that a mapping of the PBPK model to a compartmental model can be done to optimize the parameters in the PBPK model to provide a future framework for developing a population physiologically based pharmacokinetic model. 44 refs., 3 figs., 1 tab.

Weisel, C.; Yu, R.; Roy, A.; Georgopoulos, P. [Environmental and Occupational Health Sciences Institute, Piscataway, NJ (United States)



Industrial hygienist's view: relationships between industrial hygiene sampling, human exposure standards and experimental toxicology  

Microsoft Academic Search

The practical consequences of implicit workplace exposure variability is discussed. The relationship between toxicodynamic time constants and the proper selection of both short-term and long-term exposure standards is discussed. The variability of airborne workplace contaminant concentrations is the feature which most clearly distinguishes occupational exposures from the typical exposure protocols of experimental toxicology. Nevertheless, permissible exposure limits are usually set





EPA Science Inventory

Exposure scenarios are a tool to help the assessor develop estimates of exposure, dose, and risk. An exposure scenario generally includes facts, data, assumptions, inferences, and sometimes professional judgment about how the exposure takes place. The human physiological and beh...


Study of temperature distributions in wafer exposure process  

NASA Astrophysics Data System (ADS)

During the exposure process of photolithography, wafer absorbs the exposure energy, which results in rising temperature and the phenomenon of thermal expansion. This phenomenon was often neglected due to its limited effect in the previous generation of process. However, in the new generation of process, it may very likely become a factor to be considered. In this paper, the finite element model for analyzing the transient behavior of the distribution of wafer temperature during exposure was established under the assumption that the wafer was clamped by a vacuum chuck without warpage. The model is capable of simulating the distribution of the wafer temperature under different exposure conditions. The flowchart of analysis begins with the simulation of transient behavior in a single exposure region to the variation of exposure energy, interval of exposure locations and interval of exposure time under continuous exposure to investigate the distribution of wafer temperature. The simulation results indicate that widening the interval of exposure locations has a greater impact in improving the distribution of wafer temperature than extending the interval of exposure time between neighboring image fields. Besides, as long as the distance between the field center locations of two neighboring exposure regions exceeds the straight distance equals to three image fields wide, the interacting thermal effect during wafer exposure can be ignored. The analysis flow proposed in this paper can serve as a supporting reference tool for engineers in planning exposure paths.

Lin, Zone-Ching; Wu, Wen-Jang


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.



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 Deterministic Mathematical Model for Quantitative Estimation of Historical Exposure  

Microsoft Academic Search

A deterministic mathematical model has been developed for quantitative reconstruction of historical exposure. The model takes into account the causal variables actually responsible for changes in exposure and the interdependence between mean exposures in consecutive time periods. The effects of causal variables are described by step functions. In contrast, statistical modeling, a popular alternative strategy, often employs ad hoc exploratory




Computing transient exposure to indoor pollutants  

SciTech Connect

A computer code, CORRAL, is used to compute the transient levels of gases and respirable particulates in a residence. Predictions of time-varying exposure to radon (from the outside air, soil and well water) and respirable particulates (from outside air, wood stove operation and cigarette smoke) for a mother and child over 24 hours are made. Average 24-hour radon exposures are 13 times background (0.75 pCi/l) for the child and 4.5 times background for the mother. Average 24-hour respirable particulate exposures are 5.6 times background (100 3/) for the mother and 4.2 times background for the child. The controlling parameters examined are source location, flow rates between rooms, air infiltration rate and lifestyle. The first three are shown to influence the formation of local pockets of high concentration of radon and particulates, and the last parameter shows that lifestyle patterns ultimately govern individual exposure to these pockets of high concentrations. The code is useful for examination of mitigation measures to reduce exposure and examination of the effects that the controlling parameters have on exposure to indoor pollutants.

Owczarski, P.C.; Parker, G.B.



Exposing fetal drug exposure.  


Pregnancy neither protects women from susceptibility to illness nor generally decreases drug dosage requirements of preexisting pharmacotherapy. Thus, a major concern of drug use during pregnancy is maintenance of maternal health while minimizing fetal drug exposure. Important assumptions in reproductive medicine are that fetal exposure to any medication can present risks in pregnancy--because not all risks are known, as little exposure as possible is desirable. PMID:21593755

DeVane, L; Goetzl, L M; Ramamoorthy, S



Pesticide exposure assessment  

Microsoft Academic Search

Unintended, accidental, or unavoidable human exposures may result from pesticide use. Risk Characterization provides registrants, regulators, and the public a means to assess relative risks of pesticide use. Exposure Assessments are less standardized. Potential Dermal Exposure (PDE; mg\\/kg) is the amount of contact with the potential for dermal absorption (DA). Mixer\\/loader\\/applicator data developed using passive dosimetry and skin washing forms

Robert I. Krieger



Modelling of Operator Exposure  

Microsoft Academic Search

\\u000a The methodologies are reviewed for predicting exposure to pesticides of agricultural operators, in the context of pre-registration\\u000a risk assessment, with specific focus on the European registration. Exposure modelling allows predictions of exposure doses,\\u000a which may be used in risk assessment for decision-making. Relevant targets for risk assessment are mixers, loaders, applicators,\\u000a workers and bystanders. Risk can be described as a

Antonella Fait; Bengt S. Iversen


Wrestling with rep exposure  

Microsoft Academic Search

A central methodological problem in programming with multiple levels of abstractionsis the loosely defined problem of rep exposure. This paper traces the problemof rep exposure to the precisely defined notion of abstract aliasing. The paper alsooutlines a statically-enforceable discipline for avoiding abstract aliasing, but theoutline is incomplete.0 IntroductionThe danger of rep exposure arises when a reference to a mutable component

David L. Detlefs; Rustan Leino; Greg Nelson



Latency models for analyses of protracted exposures.  


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



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


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

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



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



Subjective ratings of upper extremity exposures: Inter-method agreement with direct measurement of exposures  

Microsoft Academic Search

This study examined the agreement of subjective ratings of upper extremity exposures with corresponding direct measurements obtained simultaneously from workers. Psychophysical ratings of exposure, based on the Borg CR-10 scale, were obtained for the period of time in which direct measurements were acquired using electrogoniometers (wrist), electroinclinometers (shoulder) and electromyography (grip force). Subjects were selected from workers at two automobile

Bryan Buchholz; Jung-Soon Park; Judith E. Gold; Laura Punnett



Sufficient vitamin D from casual sun exposure?  


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



Models for human exposure to air pollution  

SciTech Connect

Four models for human exposure to air pollution are discussed and compared. Simple microenvironment monitoring measures pollutant concentrations at fixed locations, regarded as proxies for similar locations or microenvironments. This model does not require pollutant measurements on the individual level, therefore is easy to implement. However, the model can be used only to estimate the average exposure in a population and does not provide any estimate of the variability and distribution of individual exposures. Replicated microenvironment monitoring provides some estimates of the variability and distribution. However, because of the possible discrepancy between the microenvironment concentration distribution and the individual concentration distribution, some adjustment might be necessary. Integrated personal monitoring allows direct estimation of the average exposure as well as the variability and distribution of individual exposures. Coupled with the appropriate time budget data, a regression analysis can be applied to estimate the contribution from each microenvironment type.

Duan, N.




EPA Science Inventory

This presentation provides a general overview of SHEDS model features, describes algorithms in the SHEDS-Air Toxics model that focus on mobile source exposures and multipathway exposures, and presents examples of results from application of the SHEDS-Air Toxics model to benzene i...


Avian inhalation exposure chamber  


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)



Avian inhalation exposure chamber  


An exposure system is designed 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. 2 figs.

Briant, J.K.; Driver, C.J.



Radiation Exposure Compensation Program  

NSDL National Science Digital Library

This is the Justice Department's Radiation Exposure Compensation Program homepage. This site features information about the Radiation Exposure Compensation Act, including claimant categories, claim forms, and the Energy Employees Occupational Illness Compensation Program Act. This site also provides a table illustrating a summary of all claims received and compensation paid to date.

Program, U. S.



Microsoft Academic Search

A model of exposure to isocyanates, based on knowledge of industrial processes and starting materials and the results of industrial hygiene surveys, is proposed. This model of exposure suggests the concentration and physical form of airborne isocyanate monomers and oligomers. A new sampling and analytical system was developed that is capable of determining the physical and chemical characteristics of occupational

Jacques Lesage; Nicole Goyer; France Desjardins; Jean-Yves Vincent; Guy Perrault




EPA Science Inventory

The development of the latest version of the Exposure Factors Handbook (EFH): 2011 Edition (EPA/600/R-09/052F) has maintained the need for a more comprehensive program that addresses issues related to exposure factors. Since the first version of the EFH was r...



EPA Science Inventory

The planned interagency National Children's Study (NCS) will be studying a number of exposure issues in the context of health and well-being of infants and young children from pre-conception to age 21. Some of the important environmental exposure questions for NCS, include: how c...


Exposure assessment in auto collision repair shops.  


Workers in auto collision shops are exposed to a variety of chemical and physical hazards. Previous studies have focused on measuring levels of isocyanates, but little is known about exposures to dust, noise, and solvents. In preparation for an intervention effectiveness study in small collision repair businesses, sampling was conducted on 3 consecutive days in four representative businesses with three to seven employees. Full-shift and task-specific exposures were measured for dust and solvents (for operations other than painting and spray gun cleaning). Full-shift personal exposures and tool-specific noise levels were also evaluated. Samples of banded earplugs were distributed to employees and feedback was collected after 1 week of wear time. Dust and solvent exposures did not exceed the OSHA PELs. Noise exposure doses were below the OSHA PEL; however, 4 of the 18 measurements were in excess of the ACGIH® threshold limit value. The majority of tools generated noise levels above 85 dBA. Air guns, wrenches, cutoff wheels, and air drills generated noise levels with the 5th percentile above 90 dBA. Mean noise levels generated by hammers, grinders, and ratchets were also above 95 dBA. Three pairs of banded earplugs had the best reviews in terms of comfort of use. This study was conducted during a time when all shops reported relatively low production levels. Noise exposure results suggest that it is likely that technicians' 8-hr time-weighted average exposures may be in excess of 85 dBA during periods of higher production, but exposures to dust and solvents are unlikely to approach OSHA exposure limits. These pilot test results will be useful when developing recommendations and technical assistance materials for health and safety interventions in auto collision repair businesses. PMID:21660833

Bejan, Anca; Brosseau, Lisa M; Parker, David L



Prenatal cocaine exposure and infant cognition  

PubMed Central

The present study examined the relationship of prenatal cocaine exposure to infant information processing in the first year of life. In a prospective, longitudinal study of 177 cocaine-exposed and 175 non-exposed infants, the Fagan Test of Infant Intelligence (FTII) was used to measure attention, visual recognition memory and information processing speed at 6.5 and 12 months of age. Groups were compared over time using mixed linear model analyses. Prenatal cocaine exposure predicted poorer visual recognition memory at 12 months, with exposed infants obtaining lower mean scores and a higher percentage of scores in the risk range. Across exposure groups, information processing speed increased with age, demonstrating a developmental effect. Tobacco and marijuana exposures were related to faster looking times, which did not relate to visual recognition memory. Cognitive deficits and attentional problems noted in prior studies of cocaine-exposed children at later ages may be detectable in infancy.

Singer, Lynn T.; Eisengart, Laurie J.; Minnes, Sonia; Noland, Julia; Jey, Arthur; Lane, Courtney; Min, Meeyoung O.



Tetrachloroethylene Emissions and Exposure in Dry Cleaning  

Microsoft Academic Search

Tetrachloroethylene (PCE) emissions and the exposure of workers in six commercial and three industrial dry-cleaning establishments that use dry-to-dry machines were determined. The personal samples and area samples [8-hr time-weighted average (TWA) and short-term exposure] were collected with charcoal tubes and passive monitors. The temporal variation of PCE concentration in the workplace air was monitored using a Fourier transform infrared

J. Räisänen; R. Niemelä; C. Rosenberg



Estimating equations for biomarker based exposure estimation under non-steady-state conditions.  


Unrealistic steady-state assumptions are often used to estimate toxicant exposure rates from biomarkers. A biomarker may instead be modeled as a weighted sum of historical time-varying exposures. Estimating equations are derived for a zero-inflated gamma distribution for daily exposures with a known exposure frequency. Simulation studies suggest that the estimating equations can provide accurate estimates of exposure magnitude at any reasonable sample size, and reasonable estimates of the exposure variance at larger sample sizes. PMID:21668990

Bartell, Scott M; Johnson, Wesley O



Nuclear Energy: Radiation Exposure  

NSDL National Science Digital Library

This lesson provides an overview of the sources and potential effects of radiation exposure. Topics include the history of the United States' domestic nuclear power program, the concept of ionizing radiation, and how radiation dosage is measured. There is also discussion of what constitutes a lethal dose of radiation and potential sources of exposure. The lesson includes an activity in which students measure their individual yearly exposures to radiation by making an inventory of lifestyle factors that affect their potential dosage and using an online calculator to sum up the contributions from the various sources.

Pratte, John


Personal exposure of children to air pollution  

NASA Astrophysics Data System (ADS)

Changes over recent decades in outdoor concentrations of air pollutants are well documented. However, the impacts of air pollution on an individual's health actually relate not to these outdoor concentrations but to their personal exposure in the different locations in which they spend time. Assessing how personal exposures differ from outdoor concentrations, and how they have changed over recent decades, is challenging. This review focuses on the exposure of children, since they are a particularly sensitive group. Much of children's time is spent indoors, and childhood exposure is closely related to concentrations in the home, at school, and in transport. For this reason, children's personal exposures to air pollutants differ significantly from both those of adults and from outdoor concentrations. They depend on a range of factors, including urbanisation, energy use, building design, travel patterns, and activity profiles; analysis of these factors can identify a wider range of policy measures to reduce children's exposure than direct emission control. There is a very large variation in personal exposure between individual children, caused by differences in building design, indoor and outdoor sources, and activity patterns. Identifying groups of children with high personal exposure, and their underlying causes, is particularly important in regions of the world where emissions are increasing, but there are limited resources for environmental and health protection. Although the science of personal exposure assessment, with the associated measurement and modelling techniques, has developed to maturity in North America and western Europe over the last 50 years, there is an urgent need to apply this science in other parts of the world where the effects of air pollution are now much more serious.

Ashmore, M. R.; Dimitroulopoulou, C.


Risk assessment using exposure intensity: an application to vermiculite mining.  

PubMed Central

Estimation of exposure-response relations from epidemiological data is complicated by the fact that exposures usually vary in intensity over time. Cumulative exposure indices, which do not separate the effects of intensity and duration, are commonly used to circumvent this problem. In this paper the estimation of relative risk for specific ranges of exposure intensity from such data is considered using existing statistical methods for fitting multivariate relative risk models. This has the advantage that it does not assume that exposure intensity and duration have equivalent effects on risk. It also throws light on the possible existence of a threshold. The procedure was applied to data from a cohort of 406 vermiculite miners to examine the lung cancer risk associated with exposure to fibrous tremolite, which contaminated the vermiculite. The pattern of exposure-response differed substantially from that obtained using a cumulative exposure index to assess risk.

Vacek, P M; McDonald, J C



Estimating Exposure of Terrestrial Wildlife to Contaminants  

SciTech Connect

This report presents a general model for exposure of terrestrial wildlife to contaminants (Sect. 2), methods for estimating parameters of the model (Sect. 3), species specific parameters for endpoint species on the Oak Ridge Reservation (ORR) (Sect. 4), and a sample application (Sect. 5). Exposure can be defined as the coincidence in both space and time of a receptor and a stressor, such that the receptor and stressor come into contact and interact (Risk Assessment Forum 1992). In the context of ecological risk assessment, receptors include all endpoint species or communities identified for a site [see Suter (1989) and Suter et al. (1994) for discussions of ecological endpoints for waste sites]. In the context of waste site assessments, stressors are chemical contaminations, and the contact and interaction are uptake of the contaminant by the receptor. Without sufficient exposure of the receptor to the contaminants, there is no ecological risk. Unlike some other endpoint assemblages, terrestrial wildlife are significantly exposed to contaminants in multiple media. They may drink or swim in contaminated water, ingest contaminated food and soil, and breath contaminated air. In addition, because most wildlife are mobile, moving among and within habitats, exposure is not restricted to a single location. They may integrate contamination from several spatially discrete sources. Therefore, exposure models for terrestrial wildlife must include multiple media. This document provides models and parameters for estimating exposure of birds and mammals. Reptiles and amphibians are not considered because few data exist with which to assess exposure to these organisms. In addition, because toxicological data are scarce for both classes, evaluation of the significance of exposure estimates is problematic. However, the general exposure estimation procedure developed herein for birds and mammals is applicable to reptiles and amphibians. Exposure models must be appropriate to the assessment endpoints. The models presented herein are models of the exposure of individual organisms, but except for threatened and endangered species, all the wildlife endpoints for the ORR are for populations (Suter et al. 1994). The use of organism exposures is appropriate because of the need to integrate exposure estimates with exposure-response information which is expressed as organism-level responses. The conversion of individual exposure to population effects occurs in the risk characterization. Conceptually, the conversion of organism-level exposures to the population level can be made in two ways. First, it may be assumed that there is a distinct population on the site so that the exposure of the population is the exposure of all the individuals. This assumption is appropriate for small organisms on large sites, particularly if the site constitutes a distinct habitat that is surrounded by inappropriate habitat. For example, a grassy site surrounded by forest or industrial development might support a distinct population of voles. The risks to that population can be estimated directly from the exposures of the individual organisms. Second, it may be assumed that a certain number of individuals are exposed to contaminants out of a larger population. For example, a certain proportion of a deer herd may forage on a site or a pair of hawks may hunt on a site. The estimated exposure of these individuals will result in estimation of certain effects on those individuals, and the resulting population risks will need to be characterized. In either case, the organism level exposure models are appropriate.

Sample, B.E.



Benzene and total hydrocarbons exposures in the downstream petroleum industries.  


A review of studies, including both articles published in peer-reviewed journals and reports that were not peer reviewed, regarding occupational exposure to benzene and total hydrocarbons in the downstream petroleum industry operations was performed. The objective was to provide a broad estimate of exposures by compiling exposure data according to the following categories: refinery, pipeline, marine, rail, bulk terminals and trucks, service stations, underground storage tanks, tank cleaning, and site remediations. The data in each category was divided into personal occupational long-term and short-term samples. The summarized data offers valuable assistance to hygienists by providing them with an estimate and range of exposures. The traditional 8-hour time-weighted average (TWA) exposure and the 40-hour workweek do not generally coincide with exposure periods applicable to workers in marine, pipeline, railcar, and trucking operations. They are more comparable with short-term exposure or task-based exposure assessments. The marine sector has a large number of high exposures. Although relatively few workers are exposed, their exposures to benzene and total hydrocarbons are sometimes an order of magnitude higher than the respective exposure limits. It is recommended that in the future, it would be preferable to do more task-based exposure assessments and fewer traditional TWA long-term exposure assessments within the various sectors of the downstream petroleum industry. PMID:11331990

Verma, D K; Johnson, D M; Shaw, M L; des Tombe, K


[Dermal exposure and absorption].  


Dermal exposure assessment explores the dynamic interaction between environmental contaminants and the skin. The measure of skin exposure can be made using direct methods (interception techniques, removal techniques from skin, in situ detection) or indirect methods (biological monitoring, removal techniques from surfaces). The selection of the appropriate sampling method will depend on a range of factors (the sampling objectives, the compartment or transport process of interest, the nature of the agent and the analytical methods to be used) and should be part of a coherent and documented sampling strategy. In this work we describe the processes leading to exposure, in relation to the presence of clothing or protective garments, discuss on factors that influence skin penetration (both the physiologic characteristics of the skin and the physico-chemical nature of the compound that comes into contact with the skin) with the purpose to assess and manage the risk of skin exposure. PMID:21438233

Aprea, M C


Occupational Exposure to Lead  


... Headaches Stomachaches and cramps What is my employer's responsibility for lead in the workplace? The Lead Standard is a federal and state regulation (law) that requires employers to follow guidelines to protect workers from harmful lead exposure. An important part ...



EPA Science Inventory

The Exposure Assessment Facility Core will continue to collect environmental measures including personal and indoor air monitoring and repeat collection of dust samples from the home and biologic measures including urine and blood samples collected from the mother during pregn...


Insecticide Exposure in Parkinsonism.  

National Technical Information Service (NTIS)

A series of behavioral, neurochemical, and immunocytochemical studies were undertaken to characterize the possible role of insecticide exposure in the etiology of Parkinson's disease as it may relate to Gulf War Syndrome. The insecticides under study are ...

J. R. Bloomquist




EPA Science Inventory

This system is a listing of persons (general population) with documented exposure to select hazardous substances (superfund related). All adverse health outcomes are monitored prospectively. Retrospective identification of adverse health outcomes (usually verified by medical reco...


Exposure Assessment in Risk Assessment.  

National Technical Information Service (NTIS)

The assessment of exposure is an important component of the risk assessment process. Exposure information is used in risk assessment in at least two ways: (1) in the identification of hazards and the epidemiologic research investigating exposure-response ...

R. F. Herrick



Modeling Indoor Concentrations and Exposures.  

National Technical Information Service (NTIS)

The paper discusses the use of an indoor air quality model, EXPOSURE, to predict pollutant concentrations and exposures. The effects of indoor air pollutants depend on the concentrations of the pollutants and the exposure of individuals to the pollutants....

L. E. Sparks



Changes in Television and Magazine Exposure and Eating Disorder Symptomatology  

Microsoft Academic Search

The relationship between girls' media exposure and their development of eating disorder symptomatology was assessed. At Time 1 and Time 2 (16 months later), participants (N = 374; M age = 12.0) completed a questionnaire that assessed eating disorder sympto-matology and television and fashion magazine exposure. Girls were divided into 3 groups: increased, decreased, or no change in eating disorder

Kimberley K. Vaughan; Gregory T. Fouts



Leisure noise exposure in adolescents and young adults  

Microsoft Academic Search

Many efforts have been made in recent times to combat occupational noise exposure, and noise preventive measures in many industries seem promising. Less positive, however, are noise exposure situations during leisure time activities. New noisy leisure activities are cropping up, and sound levels appear to have increased over the years. There is thus reason for concern over such noisy activities

A. Axelsson



Cancer and developmental exposure to endocrine disruptors.  

PubMed Central

Developing organisms have increased susceptibility to cancer if they are exposed to environmental toxicants during rapid growth and differentiation. Human studies have demonstrated clear increases in cancer after prenatal exposure to ionizing radiation, and there is suggestive evidence that brain tumors and leukemia are associated with parental exposures to chemicals. Animal experiments have demonstrated increased tumor formation induced by prenatal or neonatal exposure to a variety of chemicals, including direct-acting carcinogens and drugs. Recently, natural estrogens have been classified as known human carcinogens. Prenatal exposure to natural and synthetic estrogens is associated with increases in breast and vaginal tumors in humans as well as uterine tumors in animals. Synthetic halogenated chemicals increase liver tumors after early life-stage exposure. Recently, a prototypical endocrine-disrupting compound, 2,3,7,8-tetrachlorodibenzo-p-dioxin, has been shown to be a developmental toxicant of the mammary gland in rodents. Dioxin alters multiple endocrine systems, and its effects on the developing breast involve delayed proliferation and differentiation of the mammary gland, as well as an elongation of the window of sensitivity to potential carcinogens. Implications of these new findings suggest that causes of endocrine-related cancers or susceptibility to cancer may be a result of developmental exposures rather than exposures existing at or near the time of tumor detection.

Birnbaum, Linda S; Fenton, Suzanne E



Reviewing the exposure meter constant: improving the exposure equation  

NASA Astrophysics Data System (ADS)

A careful mathematical analysis of the meaning of variables and equations used in standards for exposure meters and the determination of sensitivities S demonstrates that standards and authors of many photographic texts have erred in interpretations and applications of the common exposure equation. This article concludes that it is inappropriate to use the exposure meter constant Ks as an exposure meter calibration constant because it is essentially a label for a product of characteristics of the photosensitive array employed (the reference exposure Ho = Hsp/S and the midtone shift M = Hmid/Hsp). It also concludes that the sensitivity and the common exposure equation ultimately depend on the midtone photosensitive exposure target Hmid. This midtone exposure equation can be generalized by including a shift to a arbitrary (non-midtone) photosensitive exposure target in its derivation. This more general exposure equation includes the exposure compensation and eliminates the need for exposure indices. Analysis of the exposure equation for incidentlight exposure meters shows that these meters avoid the vagaries of the current scene by calculating exposure for a potentially very different standard scene and often can be, in effect, less accurate in exposure calculations than reflectedlight exposure meters.

Prais, Michael G.



Time After Time  

NSDL National Science Digital Library

Students use a variety of strategies and techniques to develop an understanding of telling time. They use estimation to tell time, using seconds, hours, and minutes in order to choose reasonable time estimates for given activities. Students use pictures, words, and symbols in order to read, write, and represent time to the nearest minute. Students determine elapsed time when given a start time, counting up using minutes and hours.

Service, National S.



Statistical methods for describing occupational exposure measurements.  


An important step in studies relating worker health to industrial exposure is the estimation of mean exposure levels. The investigator frequently has to rely on industrial hygiene measurements collected for other purposes. Samples may have been taken at several companies on different dates, and on each occasion multiple individual samplers may have been employed. Often it is not recognized that readings from such a hierarchical arrangement are correlated; for example, samples taken at the same time and location are more alike than samples taken on different days. This correlation invalidates the commonly used standard errors of sample means and the usual sample standard deviation. A component of variance analysis is suggested which quantifies within-day, between-day and between-company variation. Estimators of mean exposure are presented with correct standard errors. The techniques are illustrated by a small set of data and by a recent study of exposures to styrene in 36 companies manufacturing reinforced plastics. PMID:4050679

Samuels, S J; Lemasters, G K; Carson, A



Fetal alcohol exposure: consequences, diagnosis, and treatment.  


Maternal alcohol use during pregnancy is prevalent, with as many as 12% of pregnant women consuming alcohol. Alcohol intake may vary from an occasional drink, to weekly binge drinking, to chronic alcohol use throughout pregnancy. Whereas there are certain known consequences from fetal alcohol exposure, such as fetal alcohol syndrome, other effects are less well defined. Craniofacial dysmorphologies, abnormalities of organ systems, behavioral and intellectual deficits, and fetal death have all been attributed to maternal alcohol consumption. This review article considers the theoretical mechanisms of how alcohol affects the fetus, including the variable susceptibility to fetal alcohol exposure and the implications of ethanol dose and timing of exposure. Criteria for diagnosis of fetal alcohol syndrome are discussed, as well as new methods for early detection of maternal alcohol use and fetal alcohol exposure, such as the use of fatty acid ethyl esters. Finally, current and novel treatment strategies, both in utero and post utero, are reviewed. PMID:23322082

Pruett, Dawn; Waterman, Emily Hubbard; Caughey, Aaron B



Asbestos exposure in buildings  

SciTech Connect

Asbestos-related diseases are dose-related. Among these, asbestosis has occurred only with the heavy exposures of the past, is a disappearing disease, and is of no concern with the very small exposures from building occupancy. A possibly increased incidence of lung cancer has been included in risk analysis, but probably is also related to high exposure in that both epidemiologic and experimental data suggest a link between the process of alveolar inflammation and fibrogenesis and carcinogenesis. The major concern has been mesothelioma in that it has occurred with much lower household and neighborhood exposure. Additionally, anxiety concerning buildings with ACM has been heightened by finding of friable asbestos in about 20% of public buildings, discovery of environmental asbestos fibers and asbestos bodies in autopsies, and demonstration of a linear relationship between exposure and lung cancer risk in occupational groups, inviting extrapolation to a much lower dose. Legislative and regulatory mandates, promotional activities of abatement companies, adverse court decisions placing the onus of repairs on asbestos manufacturers, and a pandemic of mediagenic disease' all have contributed to panic among building owners, school boards, insurers, and others. In that there is neither clinical nor epidemiologic support for asbestos-related disease from building occupancy, risk estimates have been based on extrapolation from past experience with generally high-dose occupational exposure. However, only a few epidemiologic studies have contained quantitative estimates of exposure, and these have been measured in terms of all particles, with conversion to asbestos fibers uncertain and the fiber type and dimension largely unknown.

Gaensler, E.A. (Department of Surgery, Boston University School of Medicine, MA (United States))



Exposure Assessment and Modeling of Quartz in Swedish Iron Foundries for a Nested Case-Control Study on Lung Cancer  

Microsoft Academic Search

Exposure assessment of quartz in Swedish iron foundries was performed based on historical and present measurement data. To evaluate the exposure-response relationship between quartz exposure and lung cancer, we modeled quartz exposure from our database of measurements using determinants job title, time period, and company. Based on these modeled exposure data, we conducted a nested case-control evaluation. In our database,

Lena Andersson; Ing-Liss Bryngelsson; Yen Ngo; Carl-Göran Ohlson; Håkan Westberg



Variability in Endotoxin Exposure Levels and Consequences for Exposure Assessment  

Microsoft Academic Search

Objectives: Workers in many industries are exposed to endotoxins, which may cause adverse health effects. In exposure assessment, information about exposure variability is essential. However, variability in exposure has rarely been investigated for biological agents and more specifically for endotoxin. Therefore, variance components and determinants of exposure were studied in a large database with >2000 endotoxin measurements. Methods: Data from




Acute and chronic respiratory effects of sodium borate particulate exposures.  

PubMed Central

This study examined work-related chronic abnormality in pulmonary function and work-related acute irritant symptoms associated with exposure to borate dust in mining and processing operations. Chronic effects were examined by pulmonary function at the beginning and end of a 7-year interval. Time-specific estimates of sodium borate particulate exposures were used to estimate cumulative exposure during the study interval. Change in pulmonary function over the 7 years was found unrelated to the estimate of cumulative exposure during that interval. Exposure-response associations also were examined with respect to short-term peak exposures and incidence of five symptoms of acute respiratory irritation. Hourly measures of health outcome and continuous measures of particulate exposure were made on each subject throughout the day. Whenever a subject reported one of the irritant symptoms, a symptom intensity score was also recorded along with the approximate time of onset. The findings indicated that exposure-response relationships were present for each of the specific symptoms at several symptom intensity levels. The associations were present when exposure was estimated by both day-long and short-term (15-min) time-weighted average exposures. Associations persisted after taking account of smoking, age, and the presence of a common cold. No significant difference in response rate was found between workers exposed to different types of sodium borate dusts.

Wegman, D H; Eisen, E A; Hu, X; Woskie, S R; Smith, R G; Garabrant, D H



Americans' Average Radiation Exposure  

SciTech Connect

We live with radiation every day. We receive radiation exposures from cosmic rays, from outer space, from radon gas, and from other naturally radioactive elements in the earth. This is called natural background radiation. It includes the radiation we get from plants, animals, and from our own bodies. We also are exposed to man-made sources of radiation, including medical and dental treatments, television sets and emission from coal-fired power plants. Generally, radiation exposures from man-made sources are only a fraction of those received from natural sources. One exception is high exposures used by doctors to treat cancer patients. Each year in the United States, the average dose to people from natural and man-made radiation sources is about 360 millirem. A millirem is an extremely tiny amount of energy absorbed by tissues in the body.




Biomarkers of semen exposure.  


Biomarkers of semen exposure have historically played their most important role in forensics, i.e., determining whether ejaculation took place in the course of a crime. However, it is becoming increasingly recognized that biomarkers of semen exposure can be useful in the development of new vaginal methods of HIV/sexually transmitted infections (STI) prevention and contraception. This review is based on the presentations of Drs. Michael Coppola (ContraVac, Inc.), Maurizio Macaluso (Centers for Disease Control and Prevention), Andrezej Kulczycki (University of Alabama at Birmingham), Christine Mauck (CONRAD), Robin Maguire (Population Council), and the subsequent discussion led by Drs. Susan Ballagh (CONRAD) and Johan Melendez (Johns Hopkins University) during a session entitled "Biomarkers of semen exposure" held during the conference entitled "Biomarkers for evaluation of vaginal microbicides and contraceptives: Discovery and early validation," organized by CONRAD and the Alliance for Microbicide Development in November of 2006. PMID:19218891

Mauck, Christine K



Exposure to atmospheric radon.  

PubMed Central

We measured radon (222Rn) concentrations in Iowa and Minnesota and found that unusually high annual average radon concentrations occur outdoors in portions of central North America. In some areas, outdoor concentrations exceed the national average indoor radon concentration. The general spatial patterns of outdoor radon and indoor radon are similar to the spatial distribution of radon progeny in the soil. Outdoor radon exposure in this region can be a substantial fraction of an individual's total radon exposure and is highly variable across the population. Estimated lifetime effective dose equivalents for the women participants in a radon-related lung cancer study varied by a factor of two at the median dose, 8 mSv, and ranged up to 60 mSv (6 rem). Failure to include these doses can reduce the statistical power of epidemiologic studies that examine the lung cancer risk associated with residential radon exposure. Images Figure 1 Figure 2 Figure 3 Figure 4

Steck, D J; Field, R W; Lynch, C F



Factors affecting outdoor exposure in winter: population-based study.  


The extent of outdoor exposure during winter and factors affecting it were examined in a cross-sectional population study in Finland. Men and women aged 25-74 years from the National FINRISK 2002 sub-study (n=6,591) were queried about their average weekly occupational, leisure-time and total cold exposure during the past winter. The effects of gender, age, area of residence, occupation, ambient temperature, self-rated health, physical activity and education on cold exposure were analysed. The self-reported median total cold exposure time was 7 h/week (8 h men, 6 h women),<1 h/week (2 h men, 0 h women) at work, 4 h/week (5 h men, 4 h women) during leisure time and 1 h/week (1 h men, 1.5 h women) while commuting to work. Factors associated with increased occupational cold exposure among men were: being employed in agriculture, forestry and industry/mining/construction or related occupations, being less educated and being aged 55-64 years. Factors associated with increased leisure-time cold exposure among men were: employment in industry/mining/construction or related occupations, being a pensioner or unemployed, reporting at least average health, being physically active and having college or vocational education. Among women, being a housewife, pensioner or unemployed and engaged in physical activity increased leisure-time cold exposure, and young women were more exposed than older ones. Self-rated health was positively associated with leisure time cold exposure in men and only to a minor extent in women. In conclusion, the subjects reported spending 4% of their total time under cold exposure, most of it (71%) during leisure time. Both occupational and leisure-time cold exposure is greater among men than women. PMID:16788837

Mäkinen, Tiina M; Raatikka, Veli-Pekka; Rytkönen, Mika; Jokelainen, Jari; Rintamäki, Hannu; Ruuhela, Reija; Näyhä, Simo; Hassi, Juhani



Sarcoma risk after radiation exposure.  


Sarcomas were one of the first solid cancers to be linked to ionizing radiation exposure. We reviewed the current evidence on this relationship, focusing particularly on the studies that had individual estimates of radiation doses. There is clear evidence of an increased risk of both bone and soft tissue sarcomas after high-dose fractionated radiation exposure (10?+?Gy) in childhood, and the risk increases approximately linearly in dose, at least up to 40?Gy. There are few studies available of sarcoma after radiotherapy in adulthood for cancer, but data from cancer registries and studies of treatment for benign conditions confirm that the risk of sarcoma is also increased in this age-group after fractionated high-dose exposure. New findings from the long-term follow-up of the Japanese atomic bomb survivors suggest, for the first time, that sarcomas can be induced by acute lower-doses of radiation (<5?Gy) at any age, and the magnitude of the risk is similar to that observed for other solid cancers. While there is evidence that individuals with certain rare familial genetic syndromes predisposing to sarcoma, particularly Nijmegen Breakage Syndrome, are particularly sensitive to the effects of high dose radiation, it is unclear whether this is also true in very low-dose settings (<0.1?Gy). The effects of common low-penetrance alleles on radiosensitivity in the general population have not been well-characterized. Some evidence suggests that it may be possible to identify radiation-induced sarcomas by a distinct molecular signature, but this work needs to be replicated in several dose settings, and the potential role of chemotherapy and tumor heterogeneity needs to be examined in more detail. In summary, radiation exposure remains one of the few established risk factors for both bone and soft tissue sarcomas. Similar to many other cancers children have the highest risks of developing a radiation-related sarcoma. Efforts to limit unnecessary high-dose radiation exposure, particularly in children, therefore remain important given the high fatality rates associated with this disease. PMID:23036235

Berrington de Gonzalez, Amy; Kutsenko, Alina; Rajaraman, Preetha



Ultra-accelerated natural sunlight exposure testing  

SciTech Connect

Process and apparatus are disclosed for providing ultra accelerated natural sunlight exposure testing of samples under controlled weathering without introducing unrealistic failure mechanisms in exposed materials and without breaking reciprocity relationships between flux exposure levels and cumulative dose that includes multiple concurrent levels of temperature and relative humidity at high levels of natural sunlight comprising: (a) concentrating solar flux uniformly; (b) directing the controlled uniform sunlight onto sample materials in a chamber enclosing multiple concurrent levels of temperature and relative humidity to allow the sample materials to be subjected to accelerated irradiance exposure factors for a sufficient period of time in days to provide a corresponding time of about at least a years worth of representative weathering of the sample materials.

Jorgensen, G.J.; Bingham, C.; Goggin, R.; Lewandowski, A.A.; Netter, J.C.




EPA Science Inventory

A large segment of the population uses small, gasoline powered engines on a regular basis. These small engines include lawn mowers, string trimmers, chainsaws, and snow blowers. Since emissions from many of these engines are not regulated, human exposures may be high, especiall...


Food Exposures to Lead  

PubMed Central

Exposures to lead have emanated from various sources, including food, throughout human history. Occupational and environmental exposures (especially pica) appear to account for much of the identified human disease, however, food-borne exposures deserve further investigation. Lead residues in food can result from: biological uptake from soils into plants consumed by food animals or man, usage of lead arsenate pesticides, inadvertent addition during food processing, and by leaching them improperly glazed pottery used as food storage or dining utensils. Estimates of total dietary exposure should reflect frequency distribution data on lead levels in specific food commodities in relation to the quantities actually ingested by various sample populations to distinguish degrees of risk associated with particular dietary habits. Earlier estimates of average total dietary intake of lead by adults have been reported to range from above 500 ?g/day downward with more recent estimates suggesting averages of 200 ?g/day or lower. The strengths and weaknesses of these data are discussed along with analytical and sampling considerations. FDA programs related to food surveillance, epidemiology, and toxicological investigation are briefly described.

Kolbye, Albert C.; Mahaffey, Kathryn R.; Fiorino, John A.; Corneliussen, Paul C.; Jelinek, Charles F.



Occupational lead exposure  

Microsoft Academic Search

Quantitative measures of saccadic eye movements were examined in 52 lead exposed autobody shop workers and 52 age matched controls with no history of occupational lead exposure. Three characteristics of saccadic eye movements were studied: 1) saccade accuracy; 2) number of overshoots; and 3) maximum velocity. The results indicated that workers exposed to inorganic lead showed a decrease in saccade

Linda Glickman; José A. Valciukas; Ruth Lilis; Irving Weisman



Hydrofluoric acid dermal exposure.  


A retrospective review of 237 consecutive cases of dermal exposure to dilute (6-11%) hydrofluoric acid (HF)- containing rust stain remover consumer products reported to the Rocky Mountain Poison and Drug Center during 1986 was done to evaluate the toxicity of these agents and the efficacy of topical treatment with calcium gluconate gel. In 148 cases (62%), failure to follow manufacturers' recommended safety procedures was the likely cause of exposure. 219 patients developed the following symptoms: dermal swelling, redness, or both (131, 55%); blistering (12, 5%); black discoloration under fingernails (12, 5%); or pain without reported dermal changes (64, 27%). Local complications were noted in 7 cases (3%) (infection, 4 cases; fingertip dermal necrosis, 3 cases). No systemic toxicity was noted. 116 patients (49%) received treatment with topical calcium gluconate gel; 53 were followed until complete resolution of symptoms. There appeared to be a relationship between earlier initial gel application and more rapid resolution of signs and symptoms. Some degree of dermal injury may be quite common following exposure to dilute (6-11%) HF-containing rust stain remover consumer products. Failure to follow manufacturers' recommended safety procedures may be responsible for many exposures. Treatment with topical calcium gluconate gel may be effective, and more rapid resolution of signs and symptoms may occur with earlier initiation of this therapy. PMID:2741315

el Saadi, M S; Hall, A H; Hall, P K; Riggs, B S; Augenstein, W L; Rumack, B H



Methadone exposure during lactation  

PubMed Central

ABSTRACT QUESTION One of my patients is currently using methadone for maintenance of opioid dependence. She wants to breastfeed. Is breastfeeding safe for her infant? ANSWER The exposure of infants to methadone through their mothers’ breast milk is minimal. Women using methadone for treatment of opioid dependence should not be discouraged from breastfeeding. The benefits of breastfeeding largely outweigh any theoretical minimal risks.

Glatstein, Miguel Marcelo; Garcia-Bournissen, Facundo; Finkelstein, Yaron; Koren, Gideon



Scale economies in hedging foreign exchange cash flow exposures  

Microsoft Academic Search

This study finds that a sample of U.S.-based multinational corporations (MNCs) with heavy involvement in Europe is less frequently exposed to European currency risk than to non-European currency risk. Furthermore, 60% of the time, the MNCs without European exposure are found to have non-European exposure. These results are likely due to scale economies in foreign exchange exposure hedging that recently

Anna D. Martin; Laurence J. Mauer



Systematically Controlling for the Influence of Age, Sex, Hertz and Time Post-Whole-Body Vibration Exposure on Four Measures of Physical Performance in Community-Dwelling Older Adults: A Randomized Cross-Over Study  

PubMed Central

Though popular, there is little agreement on what whole-body vibration (WBV) parameters will optimize performance. This study aimed to clarify the effects of age, sex, hertz and time on four physical function indicators in community-dwelling older adults (N = 32). Participants were exposed to 2?min WBV per session at either 2?Hz or 26?Hz and outcome measures were recorded at 2, 20 and 40?min post-WBV. Timed get up-and-go and chair sit-and-reach performances improved post-WBV for both sexes, were significantly different between 2?Hz and 26?Hz treatments (P ? 0.05) and showed statistically significant interactions between age and gender (P ? 0.01). Counter movement jump and timed one-legged stance performances showed a similar but non-significant response to 2?Hz and 26?Hz treatments, though male subjects showed a distinct trended response. Age and gender should be statistically controlled and both 2?Hz and 26?Hz exert a treatment effect.

Merriman, Harold L.; Brahler, C. Jayne; Jackson, Kurt



Proteomic Analyses of Corneal Tissue Subjected to Alkali Exposure  

PubMed Central

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

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



Golfer exposure to chlorpyrifos and carbaryl following application to turfgrass.  


Exposure of golfers to pesticides following their application to turfgrass is of concern to regulators, turfgrass professionals, and consumers. Multipathway exposures were evaluated for golfers on turfgrass treated with chlorpyrifos and carbaryl. Air concentrations and transferable foliar residues (TFRs) were measured to assess potential respiratory and dermal exposures, respectively. At the same time, exposure to individuals simulating the play of golf was determined by dosimetry and urinary biomonitoring. Individual golfer exposure was determined in 76 rounds of golf following eight applications of chlorpyrifos and two applications of carbaryl. Estimated exposures to golfers following full course and full rate applications of chlorpyrifos and carbaryl were 19-68 times below current U.S. EPA acute reference dose (Rfd) values, indicating safe exposures under U.S. EPA hazard quotient criteria. Dermal exposure was determined to be the dominant exposure pathway to golfers, accounting for approximately 60% of the chlorpyrifos absorbed dose and 100% of the carbaryl absorbed dose. This study also provides a set of transfer factors (TFs) that may be used to determine dermal exposure of golfers to pesticides using transferable residue data. PMID:18598045

Putnam, Raymond A; Doherty, Jeffery J; Clark, J Marshall



Silica dust exposures during selected construction activities.  


This study characterized exposure for dust-producing construction tasks. Eight common construction tasks were evaluated for quartz and respirable dust exposure by collecting 113 personal task period samples for cleanup; demolition with handheld tools; concrete cutting; concrete mixing; tuck-point grinding; surface grinding; sacking and patching concrete; and concrete floor sanding using both time-integrating filter samples and direct-reading respirable dust monitors. The geometric mean quartz concentration was 0.10 mg/m(3) (geometric standard deviation [GSD]=4.88) for all run time samples, with 71% exceeding the threshold limit value. Activities with the highest exposures were surface grinding, tuck-point grinding, and concrete demolition (GM[GSD] of 0.63[4.12], 0.22[1.94], and 0.10[2.60], respectively). Factors recorded each minute were task, tool, work area, respiratory protection and controls used, estimated cross draft, and whether anyone nearby was making dust. Factors important to exposure included tool used, work area configuration, controls employed, cross draft, and in some cases nearby dust. More protective respirators were employed as quartz concentration increased, although respiratory protection was found to be inadequate for 42% of exposures. Controls were employed for only 12% of samples. Exposures were reduced with three controls: box fan for surface grinding and floor sanding, and vacuum/shroud for surface grinding, with reductions of 57, 50, and 71%, respectively. Exposures were higher for sweeping compound, box fan for cleanup, ducted fan dilution, and wetted substrate. Construction masons and laborers are frequently overexposed to silica. The usual protection method, respirators, was not always adequate, and engineering control use was infrequent and often ineffective. PMID:12809537

Flanagan, Mary Ellen; Seixas, Noah; Majar, Maria; Camp, Janice; Morgan, Michael


Retrospective exposure assessment for a cohort study into respiratory effects of acid anhydrides  

PubMed Central

OBJECTIVES: To estimate past exposure to phthalic (PA), trimellitic (TMA) and maleic anhydride (MA) in three alkyd resin and one cushioned flooring factory to estimate exposure-response relations in a retrospective cohort study. METHODS: Personal exposure measurements were carried out in 1992 and quantitative and qualitative information on past exposure and production processes were collected. Job titles were ranked by decreasing exposure and amalgamated into job categories and exposure groups. Multiplication factors for back calculating past exposure levels were estimated with past exposure data, or if no such data were available these factors were estimated by a panel of occupational hygienists. Exposure levels were back calculated starting with the exposure levels in 1992. RESULTS: High exposures to PA were estimated to have occurred among workers operating the PA melting pots in factory 1 (estimated exposure in 1960-9 was 2480 micrograms.m-3). Highest concentrations of TMA were estimated to have occurred among the ink mixers in factory 2 from 1979 to 1986 (554 micrograms.m-3). Exposure in most other job titles was thought to be fairly constant over time for PA, TMA, and MA. CONCLUSIONS: Exposure to acid anhydride at these factories has fallen during the period covered by the study. However, it is estimated that in only one job in factory 2 did past exposure to acid anhydride exceed the current occupational exposure standard. Accuracy of the estimated exposure is limited by a paucity of reliable past exposure data.  

van Tongeren, M. J.; Barker, R. D.; Gardiner, K.; Harris, J. M.; Venables, K. M.; Harrington, J. M.; Newman, T



Magnetic-field Exposures in the Workplace: Reference Distribution and Exposures in Occupational Groups.  


Exposures to extremely-low-frequency magnetic fields were assessed by taking personal measurements with a dosimeter calibrated at 50 Hz with a bandwidth of 40-400 Hz. The study group was a population-based random sample of 1,098 Swedish men. Exposures were determined as workday mean, median, maximum, and standard deviation, and the time fraction of the day when exposures exceeded 0.20 µT. For workday means, the 50th percentile was 0.17 µT, and the 75th percentile was 0.27 µT. For median values, the 50th percentile was 0.11 µT and the 75th percentile was 0.16 µT. The strongest correlation (Spearman rank correlation = r&infs;) found was between the workday mean and the fraction of time above 0.20 µT (r&infs; = 0.89). The authors used the same data to estimate exposures for the 100 most common occupations according to the 1990 Swedish census. A minimum of four independent measurements for each occupation was required. Among occupations with low workday mean values were earth-moving machine operator, health care worker, and concrete worker. Among occupations with high workday mean exposures were welder and electrical or electronics engineer or technician. High exposure levels were also found in occupations outside the study base, such as train engine driver and glass, ceramic, or brick worker. Exposures to magnetic fields vary widely, since levels of exposure are strongly affected by factors such as duration of exposure and distance from the source. Large variations often found between individuals within occupations could reflect variations in tasks across different workdays for the particular occupations and/or local conditions such as tools and installations, and/or how the work is organized and performed. PMID:9933877

Floderus; Persson; Stenlund



Perinatal Bisphenol A Exposure and Adult Glucose Homeostasis: Identifying Critical Windows of Exposure  

PubMed Central

Bisphenol A (BPA) is a widespread endocrine-disrupting chemical used as the building block for polycarbonate plastics. Epidemiological evidence has correlated BPA exposure with higher risk of heart disease and type 2 diabetes. However, it remains unknown whether there are critical windows of susceptibility to BPA exposure on the development of dysglycemia. This study was an attempt to investigate the critical windows and the long-term consequences of perinatal exposure to BPA on glucose homeostasis. Pregnant mice were given either vehicle or BPA (100 µg/kg/day) at different time of perinatal stage: 1) on days 1–6 of pregnancy (P1–P6, preimplantation exposure); 2) from day 6 of pregnancy until postnatal day (PND) 0 (P6–PND0, fetal exposure); 3) from lactation until weaning (PND0–PND21, neonatal exposure); and 4) from day 6 of gestation until weaning (P6–PND21, fetal and neonatal exposure). At 3, 6 and 8 months of age, offspring in each group were challenged with glucose and insulin tolerance tests. Then islet morphometry and ?-cell function were measured. The glucose homeostasis was impaired in P6-PND0 mice from 3 to 6 months of age, and this continued to 8 months in males, but not females. While in PND0-PND21 and P6-PND21 BPA-treated groups, only the 3-month-old male offspring developed glucose intolerance. Moreover, at the age of 3 months, perinatal exposure to BPA resulted in the increase of ?-cell mass mainly due to the coordinate changes in cell replication, neogenesis, and apoptosis. The alterations of insulin secretion and insulin sensitivity, rather than ?-cell mass, were consistent with the development of glucose intolerance. Our findings suggest that BPA may contribute to metabolic disorders relevant to glucose homeostasis and the effects of BPA were dose, sex, and time-dependent. Fetal development stage may be the critical window of susceptibility to BPA exposure.

Liu, Jingli; Yu, Pan; Qian, Wenyi; Li, Yan; Zhao, Jingjing; Huan, Fei; Wang, Jun; Xiao, Hang



Exposure to o-toluidine, aniline, and nitrobenzene in a rubber chemical manufacturing plant: a retrospective exposure assessment update.  


The National Institute for Occupational Safety and Health previously conducted a retrospective cancer incidence and mortality study of workers employed at a rubber chemical manufacturing plant. Compared with New York State incidence, the bladder cancer risk was 6.5 times higher for workers considered to have definite exposure to ortho-toluidine and aniline, and 4 times higher for workers with possible exposure. Exposure characterization in the original study utilized a surrogate measure based only on departments in which each worker was ever employed. As part of an update of that study, some departments in the three original exposure groups were reclassified based on a follow-up site visit; interviews with employees, management, and union representatives; and review of records including exposure data. An additional evaluation of department-job combinations, rather than only departments, was used to stratify exposure into four categories. An approximate rank of "relative" exposure level for each department-job-year combination was also assigned using a ranking scale of 0 to 10. The ranks were supported by quantitative exposure levels and by professional judgment. The numerical ranking scale was applied to each worker by multiplying the exposure rank by duration for each job held based on comprehensive individual work histories. The cumulative rank scores for this cohort ranged from 0 to 300 unit-years. The medians of the cumulative rank scores for the exposure categories showed very good agreement with increasing exposure classifications (e.g., 0.72, 4.6, 11, 14 unit-years for the four exposure categories). Workers' breathing zone air sampling data collected at this plant from 1976-2004 were well below published occupational exposure limits for these chemicals, but additional cases of bladder cancer have been reported. The exposure assessment revisions and rank estimates will be used to analyze the updated bladder cancer incidence data. PMID:22708702

Hanley, Kevin W; Viet, Susan M; Hein, Misty J; Carreón, Tania; Ruder, Avima M



Imagination or exposure causes imagination inflation  

Microsoft Academic Search

To examine the effects of exposure to complex autobiographical events on imagination inflation, subjects took part in a three stage procedure. First, they rated their confidence that a list of events had happened in their childhood. Second, subjects