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Sample records for exposure experimental studies

  1. Real versus Simulated Mobile Phone Exposures in Experimental Studies

    PubMed Central

    Panagopoulos, Dimitris J.; Johansson, Olle; Carlo, George L.

    2015-01-01

    We examined whether exposures to mobile phone radiation in biological/clinical experiments should be performed with real-life Electromagnetic Fields (EMFs) emitted by commercially available mobile phone handsets, instead of simulated EMFs emitted by generators or test phones. Real mobile phone emissions are constantly and unpredictably varying and thus are very different from simulated emissions which employ fixed parameters and no variability. This variability is an important parameter that makes real emissions more bioactive. Living organisms seem to have decreased defense against environmental stressors of high variability. While experimental studies employing simulated EMF-emissions present a strong inconsistency among their results with less than 50% of them reporting effects, studies employing real mobile phone exposures demonstrate an almost 100% consistency in showing adverse effects. This consistency is in agreement with studies showing association with brain tumors, symptoms of unwellness, and declines in animal populations. Average dosimetry in studies with real emissions can be reliable with increased number of field measurements, and variation in experimental outcomes due to exposure variability becomes less significant with increased number of experimental replications. We conclude that, in order for experimental findings to reflect reality, it is crucially important that exposures be performed by commercially available mobile phone handsets. PMID:26346766

  2. Real versus Simulated Mobile Phone Exposures in Experimental Studies.

    PubMed

    Panagopoulos, Dimitris J; Johansson, Olle; Carlo, George L

    2015-01-01

    We examined whether exposures to mobile phone radiation in biological/clinical experiments should be performed with real-life Electromagnetic Fields (EMFs) emitted by commercially available mobile phone handsets, instead of simulated EMFs emitted by generators or test phones. Real mobile phone emissions are constantly and unpredictably varying and thus are very different from simulated emissions which employ fixed parameters and no variability. This variability is an important parameter that makes real emissions more bioactive. Living organisms seem to have decreased defense against environmental stressors of high variability. While experimental studies employing simulated EMF-emissions present a strong inconsistency among their results with less than 50% of them reporting effects, studies employing real mobile phone exposures demonstrate an almost 100% consistency in showing adverse effects. This consistency is in agreement with studies showing association with brain tumors, symptoms of unwellness, and declines in animal populations. Average dosimetry in studies with real emissions can be reliable with increased number of field measurements, and variation in experimental outcomes due to exposure variability becomes less significant with increased number of experimental replications. We conclude that, in order for experimental findings to reflect reality, it is crucially important that exposures be performed by commercially available mobile phone handsets.

  3. Systemic Effects of Wood Smoke in a Short-Term Experimental Exposure Study of Atopic Volunteers

    PubMed Central

    Bønløkke, Jakob Hjort; Riddervold, Ingunn Skogstad; Grønborg, Therese Koops; Skogstrand, Kristin; Hougaard, David M.; Barregard, Lars; Sigsgaard, Torben

    2014-01-01

    Objective: To investigate whether short-term systemic effects of wood smoke occurred in atopic subjects after experimental wood smoke exposures. Methods: A double-blind climate chamber study was conducted on 20 healthy atopic subjects with exposures to filtered air and wood smoke. Pneumoproteins, coagulation and adhesion factors, and cytokines were measured. Heart rate was monitored with pulse monitors. Data were analyzed with mixed models. Results: Few differences in the outcomes were observed. Plasma tissue factor remained elevated during filtered air exposure (P = 0.002). P-selectin declined independent of exposure (P = 0.0006). Interleukin-6 increased after filtered air (P = 0.03). Conclusions: The study confirmed previous observations among nonatopics of limited changes after a 3-hour wood smoke exposure. PMID:24451613

  4. Changing the environment to improve population health: a framework for considering exposure in natural experimental studies.

    PubMed

    Humphreys, David K; Panter, Jenna; Sahlqvist, Shannon; Goodman, Anna; Ogilvie, David

    2016-09-01

    There is renewed optimism regarding the use of natural experimental studies to generate evidence as to the effectiveness of population health interventions. Natural experimental studies capitalise on environmental and policy events that alter exposure to certain social, economic or environmental factors that influence health. Natural experimental studies can be useful for examining the impact of changes to 'upstream' determinants, which may not be amenable to controlled experiments. However, while natural experiments provide opportunities to generate evidence, they often present certain conceptual and methodological obstacles. Population health interventions that alter the physical or social environment are usually administered broadly across populations and communities. The breadth of these interventions means that variation in exposure, uptake and impact may be complex. Yet many evaluations of natural experiments focus narrowly on identifying suitable 'exposed' and 'unexposed' populations for comparison. In this paper, we discuss conceptual and analytical issues relating to defining and measuring exposure to interventions in this context, including how recent advances in technology may enable researchers to better understand the nature of population exposure to changes in the built environment. We argue that when it is unclear whether populations are exposed to an intervention, it may be advantageous to supplement traditional impact assessments with observational approaches that investigate differing levels of exposure. We suggest that an improved understanding of changes in exposure will assist the investigation of the impact of complex natural experiments in population health.

  5. Experimental and modeling study of thermal exposure of a self-contained breathing apparatus (SCBA).

    PubMed

    Donnelly, Michelle K; Yang, Jiann C

    2015-08-01

    An experimental apparatus designed to study firefighter safety equipment exposed to a thermal environment was developed. The apparatus consisted of an elevated temperature flow loop with the ability to heat the air stream up to 200°C. The thermal and flow conditions at the test section were characterized using thermocouples and bi-directional probes. The safety equipment examined in this study was a self-contained breathing apparatus (SCBA), including a facepiece and an air cylinder. The SCBA facepiece was placed on a mannequin headform and coupled to a breathing simulator that was programmed with a prescribed breathing pattern. The entire SCBA assembly was placed in the test section of the flow loop for these thermal exposure experiments. Three air stream temperatures, 100°C, 150°C, and 200°C, were used with the average air speed at the test section set at 1.4m/s and thermal exposure durations up to 1200 s. Measurements were made using type-K bare-bead thermocouples located in the mannequin's mouth and on the outer surface of the SCBA cylinder. The experimental results indicated that increasing the thermal exposure severity and duration increased the breathing air temperatures supplied by the SCBA. Temperatures of breathing air from the SCBA cylinder in excess of 60°C were observed over the course of the thermal exposure conditions used in most of the experiments. A mathematical model for transient heat transfer was developed to complement the thermal exposure experimental study. The model took into consideration forced convective heat transfer, quasi-steady heat conduction through the composite layers of the SCBA cylinder wall, the breathing pattern and action of the breathing simulator, and predicted air temperatures from the thermally exposed SCBA cylinder and temperatures at the outer surface of the SCBA cylinder. Model predictions agreed reasonably well with the experimental measurements.

  6. Auditory brainstem response changes during exposure to GSM-900 radiation: an experimental study.

    PubMed

    Kaprana, Antigoni E; Chimona, Theognosia S; Papadakis, Chariton E; Velegrakis, Stylianos G; Vardiambasis, Ioannis O; Adamidis, Georgios; Velegrakis, George A

    2011-01-01

    The objective of the present study was to investigate the possible electrophysiological time-related changes in auditory pathway during mobile phone electromagnetic field exposure. Thirty healthy rabbits were enrolled in an experimental study of exposure to GSM-900 radiation for 60 min and auditory brainstem responses (ABRs) were recorded at regular time-intervals during exposure. The study subjects were radiated via an adjustable power and frequency radio transmitter for GSM-900 mobile phone emission simulation, designed and manufactured according to the needs of the experiment. The mean absolute latency of waves III-V showed a statistically significant delay (p < 0.05) after 60, 45 and 15 min of exposure to electromagnetic radiation of 900 MHz, respectively. Interwave latency I-III was found to be prolonged after 60 min of radiation exposure in correspondence to wave III absolute latency delay. Interwave latencies I-V and III-V were found with a statistically significant delay (p < 0.05) after 30 min of radiation. No statistically significant delay was found for the same ABR parameters in recordings from the ear contralateral to the radiation source at 60 min radiation exposure compared with baseline ABR. The ABR measurements returned to baseline recordings 24 h after the exposure to electromagnetic radiation of 900 MHz. The prolongation of interval latencies I-V and III-V indicates that exposure to electromagnetic fields emitted by mobile phone can affect the normal electrophysiological activity of the auditory system, and these findings fit the pattern of general responses to a stressor. Copyright © 2010 S. Karger AG, Basel.

  7. An experimental study on the effects of exposure to magazine advertising on children's food choices.

    PubMed

    Jones, Sandra C; Kervin, Lisa

    2011-08-01

    The present study sought to determine the feasibility of an experimental research design to investigate the effects of exposure to magazine advertising on children's food choices. Children were randomized to read either a magazine with food advertisements or a magazine with no food advertisements. They then chose two food items from the intervention 'store' to eat after the session. Data were also collected on attitudes to advertising and snack food preferences. Finally, participants' parents were provided with a self-completion survey on food choices and other variables (n 24). Three vacation care centres in regional New South Wales, Australia. Children aged 5-12 years (n 47). Children in the experimental condition were more likely to choose advertised foods than those in the control group. Interestingly, the majority reported taste and healthiness as the most important factors in snack food choices; however, when faced with the actual food choice, they predominantly chose unhealthy foods (eighty-two unhealthy and only twelve healthy items were chosen). This was the first study to assess the effects on children of exposure to food advertising within the context of reading a child-targeted magazine. Importantly, even with the small sample size and venue limitations, we found that exposure to magazine advertising influenced food choices. Children's magazines are an under-researched and poorly regulated medium, with considerable potential to influence children's food choices. The present study shows that the methodology is feasible, and future studies could replicate this with larger samples.

  8. An experimental system for the study of ultrasound exposure of isolated blood vessels

    NASA Astrophysics Data System (ADS)

    Tokarczyk, Anna; Rivens, Ian; van Bavel, E.; Symonds-Tayler, Richard; ter Haar, Gail

    2013-04-01

    An experimental system designed for the study of the effects of diagnostic or therapeutic ultrasound exposure on isolated blood vessels in the presence or absence of intraluminal contrast agent is described. The system comprised several components. A microscope was used to monitor vessel size (and thus vessel functionality), and potential leakage of intraluminal 70 kDa FITC-dextran fluorescence marker. A vessel chamber allowed the mounting of an isolated vessel whilst maintaining its viability, with pressure regulation for the control of intraluminal pressure and induction of flow for the infusion of contrast microbubbles. A fibre-optic hydrophone sensor mounted on the vessel chamber using a micromanipulator allowed pre-exposure targeting of the vessel to within 150 µm, and monitoring of acoustic cavitation emissions during exposures. Acoustic cavitation was also detected using changes in the ultrasound drive voltage and by detection of audible emissions using a submerged microphone. The suitability of this system for studying effects in the isolated vessel model has been demonstrated using a pilot study of 6 sham exposed and 18 high intensity focused ultrasound exposed vessels, with or without intraluminal contrast agent (SonoVue) within the vessels.

  9. An experimental system for the study of ultrasound exposure of isolated blood vessels.

    PubMed

    Tokarczyk, Anna; Rivens, Ian; van Bavel, E; Symonds-Tayler, Richard; ter Haar, Gail

    2013-04-07

    An experimental system designed for the study of the effects of diagnostic or therapeutic ultrasound exposure on isolated blood vessels in the presence or absence of intraluminal contrast agent is described. The system comprised several components. A microscope was used to monitor vessel size (and thus vessel functionality), and potential leakage of intraluminal 70 kDa FITC-dextran fluorescence marker. A vessel chamber allowed the mounting of an isolated vessel whilst maintaining its viability, with pressure regulation for the control of intraluminal pressure and induction of flow for the infusion of contrast microbubbles. A fibre-optic hydrophone sensor mounted on the vessel chamber using a micromanipulator allowed pre-exposure targeting of the vessel to within 150 µm, and monitoring of acoustic cavitation emissions during exposures. Acoustic cavitation was also detected using changes in the ultrasound drive voltage and by detection of audible emissions using a submerged microphone. The suitability of this system for studying effects in the isolated vessel model has been demonstrated using a pilot study of 6 sham exposed and 18 high intensity focused ultrasound exposed vessels, with or without intraluminal contrast agent (SonoVue) within the vessels.

  10. Exposure to polychlorinated biphenyls and prostate cancer: population-based prospective cohort and experimental studies.

    PubMed

    Ali, Imran; Julin, Bettina; Glynn, Anders; Högberg, Johan; Berglund, Marika; Johansson, Jan-Erik; Andersson, Swen-Olof; Andrén, Ove; Giovannucci, Edward; Wolk, Alicja; Stenius, Ulla; Åkesson, Agneta

    2016-12-01

    Polychlorinated biphenyls (PCBs) are highly persistent environmental pollutants and are undesirable components of our daily food. PCBs are classified as human carcinogens, but the evidence for prostate cancer is limited and available data are inconsistent. We explored the link between non-dioxin-like PCB and grade of prostate cancer in a prospective cohort as well as in cell experiments. A population-based cohort of 32496 Swedish men aged 45-79 years was followed prospectively through 1998-2011, to assess the association between validated estimates of dietary PCB exposure and incidence of prostate cancer by grade (2789 cases, whereof 1276 low grade, 756 intermediate grade, 450 high grade) and prostate cancer mortality (357 fatal cases). In addition, we investigated a non-dioxin-like PCB153-induced cell invasion and related markers in normal prostate stem cells (WPE-stem) and in three different prostate cancer cell lines (PC3, DU145 and 22RV1) at exposure levels relevant to humans. After multivariable-adjustment, dietary PCB exposure was positively associated with high-grade prostate cancer, relative risk (RR) 1.35 [95% confidence interval (CI): 1.03-1.76] and with fatal prostate cancer, RR 1.43 (95% CI: 1.05-1.95), comparing the highest tertile with the lowest. We observed no association with low or intermediate grade of prostate cancer. Cell invasion and related markers, including MMP9, MMP2, Slug and Snail, were significantly increased in human prostate cancer cells as well as in prostate stem cells after exposure to PCB153. Our findings both from the observational and experimental studies suggest a role of non-dioxin-like PCB153 in the development of high-grade and fatal prostate cancer. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. The ethics of human volunteer studies involving experimental exposure to pesticides: unanswered dilemmas

    PubMed Central

    2010-01-01

    The controversy about the use of data from human volunteer studies involving experimental exposure to pesticides as part of regulatory risk assessment has been widely discussed, but the complex and interrelated scientific and ethical issues remain largely unresolved. This discussion paper, generated by authors who comprised a workgroup of the ICOH Scientific Committee on Rural Health, reviews the use of human experimental studies in regulatory risk assessment for pesticides with a view to advancing the debate as to when, if ever, such studies might be ethically justifiable. The discussion is based on three elements: (a) a review of discussion papers on the topic of human testing of pesticides and the positions adopted by regulatory agencies in developed countries; (b) an analysis of published and unpublished studies involving human testing with pesticides, both in the peer-reviewed literature and in the JMPR database; and (c) application of an ethical analysis to the problem. The paper identifies areas of agreement which include general principles that may provide a starting point on which to base criteria for judgements as to the ethical acceptability of such studies. However, the paper also highlights ongoing unresolved differences of opinion inherent in ethical analysis of contentious issues, which we propose should form a starting point for further debate and the development of guidelines to achieve better resolution of this matter. PMID:20718963

  12. Exposure to movie smoking, antismoking ads and smoking intensity: an experimental study with a factorial design

    PubMed Central

    Harakeh, Zeena; Engels, Rutger C M E; Vohs, Kathleen; van Baaren, Rick B; Sargent, James

    2013-01-01

    Background This study examines whether smoking portrayal in movies or antismoking advertisements affect smoking intensity among young adults. Methods We conducted an experimental study in which 84 smokers were randomly assigned using a two (no-smoking versus smoking portrayal in the movie) by three (two prosocial ads, two antismoking ads or one of each) factorial design. Participants viewed a 60-minute movie with two commercial breaks and afterwards completed a questionnaire. Smoking during the session was allowed and observed. Results Exposure to the movie with smoking had no effect on smoking intensity. Those who viewed two antismoking ads had significantly lower smoking intensity compared with those who viewed two prosocial ads. There was no interaction between movie smoking and antismoking ads. Baseline CO (carbon monoxide) level had the largest effect on smoking intensity. Conclusion These findings provide further evidence to support antismoking ads placed with movies because of their possible effect on young adult smoking behaviour. However, caution is warranted, because nicotine dependence appears to be the primary predictor of smoking intensity among young adult smokers in this study. PMID:20008155

  13. Exposure to movie smoking, antismoking ads and smoking intensity: an experimental study with a factorial design.

    PubMed

    Harakeh, Zeena; Engels, Rutger C M E; Vohs, Kathleen; van Baaren, Rick B; Sargent, James

    2010-06-01

    This study examines whether smoking portrayal in movies or antismoking advertisements affect smoking intensity among young adults. We conducted an experimental study in which 84 smokers were randomly assigned using a two (no-smoking versus smoking portrayal in the movie) by three (two prosocial ads, two antismoking ads or one of each) factorial design. Participants viewed a 60-minute movie with two commercial breaks and afterwards completed a questionnaire. Smoking during the session was allowed and observed. Exposure to the movie with smoking had no effect on smoking intensity. Those who viewed two antismoking ads had significantly lower smoking intensity compared with those who viewed two prosocial ads. There was no interaction between movie smoking and antismoking ads. Baseline CO (carbon monoxide) level had the largest effect on smoking intensity. These findings provide further evidence to support antismoking ads placed with movies because of their possible effect on young adult smoking behaviour. However, caution is warranted, because nicotine dependence appears to be the primary predictor of smoking intensity among young adult smokers in this study.

  14. Exposure to Air Ions in Indoor Environments: Experimental Study with Healthy Adults.

    PubMed

    Wallner, Peter; Kundi, Michael; Panny, Michael; Tappler, Peter; Hutter, Hans-Peter

    2015-11-10

    Since the beginning of the 20th century there has been a scientific debate about the potential effects of air ions on biological tissues, wellbeing and health. Effects on the cardiovascular and respiratory system as well as on mental health have been described. In recent years, there has been a renewed interest in this topic. In an experimental indoor setting we conducted a double-blind cross-over trial to determine if higher levels of air ions, generated by a special wall paint, affect cognitive performance, wellbeing, lung function, and cardiovascular function. Twenty healthy non-smoking volunteers (10 female, 10 male) participated in the study. Levels of air ions, volatile organic compounds and indoor climate factors were determined by standardized measurement procedures. Air ions affected the autonomous nervous system (in terms of an increase of sympathetic activity accompanied by a small decrease of vagal efferent activity): In the test room with higher levels of air ions (2194/cm³ vs. 1038/cm³) a significantly higher low to high frequency ratio of the electrocardiography (ECG) beat-to-beat interval spectrogram was found. Furthermore, six of nine subtests of a cognitive performance test were solved better, three of them statistically significant (verbal factor, reasoning, and perceptual speed), in the room with higher ion concentration. There was no influence of air ions on lung function and on wellbeing. Our results indicate slightly activating and cognitive performance enhancing effects of a short-term exposure to higher indoor air ion concentrations.

  15. Exposure to Air Ions in Indoor Environments: Experimental Study with Healthy Adults

    PubMed Central

    Wallner, Peter; Kundi, Michael; Panny, Michael; Tappler, Peter; Hutter, Hans-Peter

    2015-01-01

    Since the beginning of the 20th century there has been a scientific debate about the potential effects of air ions on biological tissues, wellbeing and health. Effects on the cardiovascular and respiratory system as well as on mental health have been described. In recent years, there has been a renewed interest in this topic. In an experimental indoor setting we conducted a double-blind cross-over trial to determine if higher levels of air ions, generated by a special wall paint, affect cognitive performance, wellbeing, lung function, and cardiovascular function. Twenty healthy non-smoking volunteers (10 female, 10 male) participated in the study. Levels of air ions, volatile organic compounds and indoor climate factors were determined by standardized measurement procedures. Air ions affected the autonomous nervous system (in terms of an increase of sympathetic activity accompanied by a small decrease of vagal efferent activity): In the test room with higher levels of air ions (2194/cm3 vs. 1038/cm3) a significantly higher low to high frequency ratio of the electrocardiography (ECG) beat-to-beat interval spectrogram was found. Furthermore, six of nine subtests of a cognitive performance test were solved better, three of them statistically significant (verbal factor, reasoning, and perceptual speed), in the room with higher ion concentration. There was no influence of air ions on lung function and on wellbeing. Our results indicate slightly activating and cognitive performance enhancing effects of a short-term exposure to higher indoor air ion concentrations. PMID:26569277

  16. Effects of exposure of the ear to GSM microwaves: in vivo and in vitro experimental studies.

    PubMed

    Aran, Jean-Marie; Carrere, Nathalie; Chalan, Yan; Dulou, Pierre-Emmanuel; Larrieu, Sophie; Letenneur, Luc; Veyret, Bernard; Dulon, Didier

    2004-10-01

    The effects of mobile phone (GSM) microwaves on the ears of guinea pigs were investigated in two in vivo experiments and one in vitro experiment. In the first experiment, three groups of eight guinea pigs had their left ear exposed for 1 h/day, 5 days/week, for 2 months, to GSM microwaves (900 MHz. GSM modulated) at specific absorption rates (SARs) of 1, 2 and 4 W/kg respectively, and a fourth group was sham-exposed. Distortion-product otoacoustic emissions (DPOAEs) were measured for each ear before exposure, at the end of the 2-month exposure period, and 2 months later. In the second experiment, the same protocol was applied to eight sham-exposed and 16 exposed guinea pigs at 4W/kg, but the auditory brainstem response (ABR) thresholds were monitored. Repeated-measures ANOVA showed no difference in DPOAE amplitudes or in ABR thresholds between the exposed and non-exposed ears and between the sham-exposed and exposed groups In the course of the second experiment, acute effects were also investigated by measuring once, in all animals, ABR thresholds just before and just after the 1-h exposure: no statistically significant difference was observed. In vitro, the two organs of Corti (OCs) of newborn rats (n=15) were isolated and placed in culture. For each animal, one OC was exposed for 24-48 h to 1 W/kg GSM microwaves, and the other was sham-exposed. After 2-3 days of culture, all OCs were observed under light microscopy. They all appeared normal to naive observers at this stage of development. These results provided no evidence that microwave radiation, at the levels produced by mobile phones, caused damage to the inner ear or the auditory pathways in our experimental animals.

  17. 1800 MHz in vitro exposure device for experimental studies on the effects of mobile communication systems.

    PubMed

    Ardoino, L; Lopresto, V; Mancini, S; Pinto, R; Lovisolo, G A

    2004-01-01

    A wire patch cell (WPC) operating at the uplink frequency band of GSM 1800 MHz has been designed for in vitro experiments with the aim of investigating the possible biological effects of electromagnetic radiation associated with cellular phones. The 1800 MHz WPC design is a direct descendant of the original 900 MHz WPC introduced by Laval et al. This system provides a homogeneous specific absorption rate distribution, using four 3.5 cm petri dishes simultaneously. Numerical dosimetry has been performed using a commercial code (CST Microwave Studio), in order to evaluate accurately the efficiency of the structure (in terms of W kg(-1) per 1 W input power) and the distribution in the chosen biological target. The numerical results have been confirmed by experimental measurements performed by measuring thermal increase due to a high power impulse. The efficiency of the structure is 1.25 +/- 25% W kg(-1) per 1 W input power higher than the efficiency of the 900 MHz WPC. A few adjustments have been made in order to use the WPC in a standard incubator and to avoid thermal increases related to the radio frequency exposure. This exposure system has been adopted for the experiments scheduled in the RAMP and GUARD projects (VFPE).

  18. Experimental studies of first mirror exposure and surface recovery on EAST

    NASA Astrophysics Data System (ADS)

    Yan, R.; Ding, R.; Chen, J. L.; Chen, L. W.

    2015-08-01

    Systematic studies of first mirrors (FMs) contamination, deposition mitigation and cleaning have been performed in EAST and laboratory. It turned out that the auxiliary systems such as gas puffing, wall conditioning and limiters could lead to a serious deposition on FMs and result in at least 60% degradation of the reflectivity. Besides, the exposure environment and depth-diameter ratios (DDRs) of the protective ducts will influence the degree of deposition mitigation and homogeneity of deposition. The reflectivity of the FM protected with duct at the wavelength of 240-400 nm could sharply decrease at the beginning of the exposure, which differs from that in the wavelength range more than 400 nm. In addition, the total and specular reflectivity of FM cleaned by radio frequency magnetron sputtering plasma (RFMSP) could be recovered by up to 90% and 80 % respectively in the wavelength range of 300-800 nm.

  19. [Clinical and experimental studies of metabolic response to chronic exposure to coal dust].

    PubMed

    Fomenko, D V; Gorokhova, L G; Panev, N I; Kazitskaia, A S; Bondarev, O I

    2011-01-01

    In miners anthracosilicosis is caused by chronic exposure to coal dust and is characterized by progressive development of the inflammatory process, the expressed disorders of lipid metabolism, and immunodeficiency. In the experiment we revealed the stages of anthracosilicosis development according to which adequate measures of prevention and correction of the disorders caused by long exposure of an organism to coal dust are recommended.

  20. An Experimental Model Using Cultured Cardiac Myocytes for a Study of the Generation of Premature Ventricular Contractions Under Ultrasound Exposure

    NASA Astrophysics Data System (ADS)

    Kudo, Nobuki; Yamamoto, Masaya

    2011-09-01

    It is known that use of a contrast agents in echocardiography increases the probability of generation of premature ventricular contractions (PVCs). As a basic study to elucidate the mechanisms and to reduce adverse effects, the generation of PVCs was investigated using cultured cardiac myocytes instead of the intact heart in vivo. Cardiac myocytes were isolated from neonatal rats and cultured on a cover slip. The myocyte sample was exposed to pulsed ultrasound with microbubbles adjacent to the myocytes, and generation of PVCs was examined with ultrasound exposure at various delay times after onset of myocyte contraction. The experimental results showed that generation of PVCs had a stable threshold delay time and that PVCs were generated only when myocytes were exposed to ultrasound with delay times longer than the threshold. The results indicate that the model used in this study is useful for revealing the mechanisms by which PVCs are induced by ultrasound exposure.

  1. Effects of aluminium exposure on brain glutamate and GABA systems: an experimental study in rats.

    PubMed

    Nayak, P; Chatterjee, A K

    2001-12-01

    It has been postulated that the neurotoxic effects of aluminium could be mediated through glutamate, an excitatory amino acid. Hence the effects of aluminium administration (at a dose of 4.2mg/kg body weight daily as aluminium chloride, hexahydrate, intraperitoneally, for 4 weeks) on glutamate and gamma-amino butyrate (GABA), an inhibitory amino acid, and related enzyme activities in different regions of the brain were studied in albino rats. The glutamate level increased significantly in the cerebrum, thalamic area, midbrain-hippocampal region and cerebellum in response to in vivo aluminium exposure. The aluminium insult also caused significant increases in glutamate alpha-decarboxylase activity in all the brain regions. However, on aluminium insult, the GABA content was not significantly changed except in the thalamic area, where it was elevated. On the contrary, the GABA-T activities of all the regions were reduced significantly in all regions except the midbrain-hippocampal region. However, the succinic semi-aldehyde content of all brain regions increased, often significantly. The aluminium-induced modification of the enzyme activities may be either due to the direct impact of aluminium or due to aluminium-induced changes in the cellular environment. The aluminium-induced differential regional accumulation of glutamate or other alterations in enzymes of the glutamate-GABA system may be one of the causes of aluminium-induced neurotoxicity.

  2. The upper airway response to pollen is enhanced by exposure to combustion particulates: a pilot human experimental challenge study.

    PubMed

    Hauser, Russ; Rice, Timothy M; Krishna Murthy, G G; Wand, Matt P; Lewis, Daniel; Bledsoe, Toni; Paulauskis, Joseph

    2003-04-01

    Although human experimental studies have shown that gaseous pollutants enhance the inflammatory response to allergens, human data on whether combustion particulates enhance the inflammatory response to allergen are limited. Therefore, we conducted a human experimental study to investigate whether combustion particulates enhance the inflammatory response to aeroallergens. "Enhancement" refers to a greater-than-additive response when combustion particulates are delivered with allergen, compared with the responses when particulates and allergen are delivered alone. Eight subjects, five atopic and three nonatopic, participated in three randomized exposure-challenge sessions at least 2 weeks apart (i.e., clean air followed by allergen, particles followed by no allergen, or particles followed by allergen). Each session consisted of nasal exposure to combustion particles (target concentration of 1.0 mg/m3) or clean air for 1 hr, followed 3 hr later by challenge with whole pollen grains or placebo. Nasal lavage was performed immediately before particle or clean air exposure, immediately after exposure, and 4, 18 and 42 hr after pollen challenge. Cell counts, differentials, and measurement of cytokines were performed on each nasal lavage. In atopic but not in nonatopic subjects, when allergen was preceded by particulates, there was a significant enhancement immediately after pollen challenge in nasal lavage leukocytes and neutrophils (29.7 X 10(3) cells/mL and 25.4 X 10(3) cells/mL, respectively). This represents a 143% and 130% enhancement, respectively. The enhanced response for interleukin-4 was 3.23 pg/mL (p = 0.06), a 395% enhancement. In atopic subjects there was evidence of an enhanced response when particulates, as compared to clean air, preceded the allergen challenge.

  3. Ophthalmic effects of petroleum dispersant exposure on common murres (Uria aalge): An experimental study.

    PubMed

    Fiorello, Christine V; Freeman, Kate; Elias, Becky A; Whitmer, Emily; Ziccardi, Michael H

    2016-12-15

    The safety of chemical dispersants used during oil spill responses is largely unknown in birds. We captured common murres in Monterey Bay, CA and exposed them to Corexit EC9500a, crude oil, or a combination in artificial seawater. We performed ophthalmic examinations and measured intraocular pressures and tear production before and after exposure. Loglinear analysis found that exposure to oil or dispersant was related to the development of conjunctivitis and corneal ulcers. Odds ratios for birds exposed to oil or dispersant were positive and significant for the development of conjunctivitis, while odds ratios for the development of corneal ulcers were positive and significant only for birds exposed to a high concentration of oil. Ocular exposure to dispersants and petroleum in seabirds may cause conjunctivitis and may play a role in the development of corneal ulcers. These results have implications for policymakers who develop protocols for the use of dispersants during marine oil spills. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Effects on the nervous system by exposure to electromagnetic fields: experimental and clinical studies

    SciTech Connect

    Hansson, H.A.

    1988-01-01

    Exposure to electromagnetic fields may cause various types of effects on nervous tissue, in severe cases even irreversible damage. The exposure conditions, i.e. frequency including type and extent of modulation, time, intensity, wave form, as well as shape, size and position of exposed subject and possible treatment with drugs, are factors determining if damage, acute or chronic, ultimately result. Long term exposure of newborn rabbits, rats and mice to electromagnetic fields of power frequency (10-14 kV/m; 50 or 60 Hz; sinusoidal wave form; 21-24 h per day) may cause affection and even damage to the nervous system. Large nerve cells showed reactive changes such as lamellar bodies and cytoskeletal alteration to an extent varying with exposure conditions. Reactive neuroglial changes as well as increase in neuroglial marker proteins could concomitantly be demonstrated. The changes seemed to be reversible although we only have incomplete data available. Exposure in vitro of frog sciatic nerve to 16-60 Hz sinusoidal low current (50-1000 nA) for 17 h induced cytoskeletal changes. Exposure of rabbits to pulsed microwaves of moderate to high intensity during 1 h per day during three days resulted in no obvious initial changes in behavior. Minimal acute damage could be demonstrated. However, after two to four months and later on both structural, immunohistochemical and biochemical changes could be documented. Radar technicians accidently and/or occupationally exposed to microwaves showed psychoneurological signs of affection as well as changes in cerebrospinal fluid protein pattern. No related changes have been noticed among matched controls.

  5. Experimental setup for radon exposure and first diffusion studies using gamma spectroscopy

    NASA Astrophysics Data System (ADS)

    Maier, Andreas; van Beek, Patrick; Hellmund, Johannes; Durante, Marco; Schardt, Dieter; Kraft, Gerhard; Fournier, Claudia

    2015-11-01

    In order to measure the uptake and diffusion of 222Rn in biological material, an exposure chamber was constructed where cell cultures, biological tissues and mice can be exposed to 222Rn-activities similar to therapy conditions. After exposure, the material is transferred to a gamma spectrometer and the decay of 214Pb and 214Bi is analyzed. From the time kinetics of these decays the total amount of the initial 222Rn concentration can be calculated. In this paper the design and construction as well as first test measurements are reported.

  6. Effects on the nervous system by exposure to electromagnetic fields: experimental and clinical studies.

    PubMed

    Hansson, H A

    1988-01-01

    Exposure to electromagnetic fields may cause various types of effects on nervous tissue, in severe cases even irreversible damage. The exposure conditions, i.e. frequency including type and extent of modulation, time, intensity, wave form, as well as shape, size and position of exposed subject and possible treatment with drugs, are factors determining if damage, acute or chronic, ultimately result. Long term exposure of newborn rabbits, rats and mice to electromagnetic fields of power frequency (10-14 kV/m; 50 or 60 Hz; sinusoidal wave form; 21-24 h per day) may cause affection and even damage to the nervous system. Large nerve cells showed reactive changes such as lamellar bodies and cytoskeletal alteration to an extent varying with exposure conditions. Reactive neuroglial changes as well as increase in neuroglial marker proteins could concomitantly be demonstrated. The changes seemed to be reversible although we only have incomplete data available. Exposure in vitro of frog sciatic nerve to 16-60 Hz sinusoidal low current (50-1000 nA) for 17 h induced cytoskeletal changes. Exposure of rabbits to pulsed microwaves of moderate to high intensity (3.1 GHz; 300 Hz modulation; peak duration 1.4 usec with maximal peak intensity about 1000 times average; 55 mW/cm; SAR in the brain cortex about 20 W/kg; increase of temperature as measured by lightguide-equipped instruments in right brain hemisphere about 1-2 degrees C) during 1 h per day during three days resulted in no obvious initial changes in behaviour. Minimal acute dam- age could be demonstrated. However, after two to four months and later on both structural, immunohistochemical and biochemical changes could be documented. Radar technicians accidently and/or occupationally exposed to microwaves showed psychoneurological signs of affection as well as changes in cerebrospinal fluid protein pattern. No related changes have been noticed among matched controls. Exposure of nervous tissue to electromagnetic fields ranging

  7. A Study to Interpret the Biological Significance of Behavior Associated with 3S Experimental Sonar Exposures

    DTIC Science & Technology

    2015-09-30

    J. O. (submitted). Biological significance of sperm whale responses to sonar: comparison with anti-predator responses. Submitted to Endangered Species Research. ... species ; 2.) quantitative comparison of behavior, and behavioral changes, during sonar presentation and playback of killer whale sounds across the 3S... species ; and 3.) quantification of the possible impacts of sonar exposure on energy expenditure by linking respiration behavior and underwater activity

  8. Divergent effects of urban particulate air pollution on allergic airway responses in experimental asthma: a comparison of field exposure studies

    PubMed Central

    2012-01-01

    Background Increases in ambient particulate matter of aerodynamic diameter of 2.5 μm (PM2.5) are associated with asthma morbidity and mortality. The overall objective of this study was to test the hypothesis that PM2.5 derived from two distinct urban U.S. communities would induce variable responses to aggravate airway symptoms during experimental asthma. Methods We used a mobile laboratory to conduct community-based inhalation exposures to laboratory rats with ovalbumin-induced allergic airways disease. In Grand Rapids exposures were conducted within 60 m of a major roadway, whereas the Detroit was located in an industrial area more than 400 m from roadways. Immediately after nasal allergen challenge, Brown Norway rats were exposed by whole body inhalation to either concentrated air particles (CAPs) or filtered air for 8 h (7:00 AM - 3:00 PM). Both ambient and concentrated PM2.5 was assessed for mass, size fractionation, and major component analyses, and trace element content. Sixteen hours after exposures, bronchoalveolar lavage fluid (BALF) and lung lobes were collected and evaluated for airway inflammatory and mucus responses. Results Similar CAPs mass concentrations were generated in Detroit (542 μg/m3) and Grand Rapids (519 μg/m3). Exposure to CAPs at either site had no effects in lungs of non-allergic rats. In contrast, asthmatic rats had 200% increases in airway mucus and had more BALF neutrophils (250% increase), eosinophils (90%), and total protein (300%) compared to controls. Exposure to Detroit CAPs enhanced all allergic inflammatory endpoints by 30-100%, whereas inhalation of Grand Rapids CAPs suppressed all allergic responses by 50%. Detroit CAPs were characterized by high sulfate, smaller sized particles and were derived from local combustion sources. Conversely Grand Rapids CAPs were derived primarily from motor vehicle sources. Conclusions Despite inhalation exposure to the same mass concentration of urban PM2.5, disparate health

  9. Health effects of exposure to nano-TiO2: a meta-analysis of experimental studies

    NASA Astrophysics Data System (ADS)

    Chang, Xuhong; Zhang, Yu; Tang, Meng; Wang, Bei

    2013-01-01

    The paper is aimed to investigate the toxicity of nano-TiO2 and its potential harmful impact on human health using meta-analysis of in vitro and short-time animal studies. Data were retrieved according to included and excluded criteria from 1994 to 2011. The combined toxic effects of nano-TiO2 were calculated by the different endpoints by cell and animal models. From analysis of the experimental studies, more than 50% showed positive statistical significance except the apoptosis group, and the cytotoxicity was in a dose-dependent but was not clear in size-dependent manner. Nano-TiO2 was detained in several important organs including the liver, spleen, kidney, and brain after entering the blood through different exposure routes, but the coefficient of the target organs was altered slightly from animal models. It is possible that nano-TiO2 can induce cell damage related to exposure size and dose. Further studies will be needed to demonstrate that nanoparticles have toxic effects on human body, especially in epidemiological studies.

  10. Exposure to soda commercials affects sugar-sweetened soda consumption in young women. An observational experimental study.

    PubMed

    Koordeman, Renske; Anschutz, Doeschka J; van Baaren, Rick B; Engels, Rutger C M E

    2010-06-01

    The present study examines the direct effects of television commercials advertising soda on actual sugar-sweetened soda consumption among young women. An experimental-observational study design was used, in which 51 female students (ages 18-29) were exposed to a 35-min movie clip, interrupted by two commercial breaks consisting of soda or water commercials. Their actual soda consumption while watching the movie clip was examined. An analysis of variance was used to examine the effects of commercial condition on soda consumption. Thirst and first glass consumed before the first commercial break were added as covariates in the analyses. Results indicated that participants assigned to the condition with soda commercials consumed 1.3 ounces more soda than participants in the water commercial condition. Exposure to soda commercials while watching a movie can have a strong influence on increasing sugar-sweetened soda consumption in young women.

  11. Experimentally Switching from Factory Made to Self-Made Cigarettes: A Preliminary Study of Perceptions, Toxicant Exposure and Smoking Behavior.

    PubMed

    Koszowski, Bartosz; Rosenberry, Zachary R; Strasser, Andrew A; Pickworth, Wallace B

    2014-04-01

    There is currently the potential for a great deal of transition and product switching among cigarette smokers. Studies on the transition when cigarette smokers switch from one type of nicotine delivery product to another are needed to understand subsequent toxicant exposure. A preliminary study was performed to determine the feasibility of experimentally replicating the transition from factory made (FM) to personal machine made (PMM) cigarette smoking. The adaptability and perceptions of the consumer and the consequent exposure to cigarette-delivered toxins were assessed. Six adults (4 men) were recruited for four laboratory visits (V1-V4) on study days 1, 5, 10 and 15, respectively. All of the participants agreed to switch from exclusive FM smoking to exclusive PMM cigarette smoking for the duration of the study. Compliance was very high among these participants. Participants progressively accepted the PMM cigarettes and became efficient producers of PMMs as evidenced in the reduced time to make 5 PMMs in the laboratory. Participants reported a preference for FM at visit 2 (V2), but had stated no preference by the fourth visit. Compared to the FMs, the PMMs at V3 (p<0.05) and V4 (p<0.10) had lower CO boost (7.3 vs. 4.1 ppm; p<0.05). Over all conditions, nicotine plasma levels averaged 18.0±2.4 ng/ml before smoking (for both FM and PMM) and 34.0±5.3 ng/mL after smoking; there were no significant differences in the plasma nicotine boost (average 17.7 and 15.4ng/ml after FM and PMM smoking, respectively). Although there were differences between individual subjects' filter butt levels of deposited solanesol the within-subject levels were remarkably similar. Puff topography measures did not vary across visits or cigarette type. Although interpretation of study results must be conservative because of the small sample size, this study demonstrates that experimentally-induced transition from FM to PMM smoking is feasible for laboratory study and the subsequent toxicant

  12. Characterization of exposure and dose of man made vitreous fiber in experimental studies.

    PubMed Central

    Hamilton, R D; Miiller, W C; Christensen, D R; Anderson, R; Hesterberg, T W

    1994-01-01

    The use of fibrous test materials in in vivo experiments introduces a number of significant problems not associated with nonfibrous particulates. The key to all aspects of the experiment is the accurate characterization of the test material in terms of fiber length, diameter, particulate content, and chemistry. All data related to fiber properties must be collected in a statistically sound manner to eliminate potential bias. Procedures similar to those outlined by the National Institute of Occupational Safety and Health (NIOSH) or the World Health Organization (WHO) must be the basis of any fiber characterization. The test material to which the animal is exposed must be processed to maximize the amount of respirable fiber and to minimize particulate content. The complex relationship among the characteristics of the test material, the properties of the delivery system, and the actual dose that reaches the target tissue in the lung makes verification of dose essential. In the case of man-made vitreous fibers (MMVF), dose verification through recovery of fiber from exposed animals is a complex task. The potential for high fiber solubility makes many of the conventional techniques for tissue preservation and digestion inappropriate. Processes based on the minimum use of aggressive chemicals, such as cold storage and low temperature ashing, are potentially useful for a wide range of inorganic fibers. Any processes used to assess fiber exposure and dose must be carefully validated to establish that the chemical and physical characteristics of the fibers have not been changed and that the dose to the target tissue is completely and accurately described. PMID:7882912

  13. Visual exposure to large and small portion sizes and perceptions of portion size normality: Three experimental studies.

    PubMed

    Robinson, Eric; Oldham, Melissa; Cuckson, Imogen; Brunstrom, Jeffrey M; Rogers, Peter J; Hardman, Charlotte A

    2016-03-01

    Portion sizes of many foods have increased in recent times. In three studies we examined the effect that repeated visual exposure to larger versus smaller food portion sizes has on perceptions of what constitutes a normal-sized food portion and measures of portion size selection. In studies 1 and 2 participants were visually exposed to images of large or small portions of spaghetti bolognese, before making evaluations about an image of an intermediate sized portion of the same food. In study 3 participants were exposed to images of large or small portions of a snack food before selecting a portion size of snack food to consume. Across the three studies, visual exposure to larger as opposed to smaller portion sizes resulted in participants considering a normal portion of food to be larger than a reference intermediate sized portion. In studies 1 and 2 visual exposure to larger portion sizes also increased the size of self-reported ideal meal size. In study 3 visual exposure to larger portion sizes of a snack food did not affect how much of that food participants subsequently served themselves and ate. Visual exposure to larger portion sizes may adjust visual perceptions of what constitutes a 'normal' sized portion. However, we did not find evidence that visual exposure to larger portions altered snack food intake. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. Effect of modifying the information and training structure on the occupational safety of health care workers in exposure to blood and body fluids: A quasi-experimental study.

    PubMed

    Sarbaz, Masoumeh; Kimiafar, Khalil; Taherzadeh, Zhila; Naderi, HamidReza; Eslami, Saeid

    2017-01-01

    This study was a quasi-experimental design to assess the effect of a Web-based information system on the occupational exposure to blood and body fluids (BBFs) among health care workers (HCWs). The outcome was the number of exposure incidents with BBFs among HCWs in both hospital A (intervention) and hospital B (control). The findings showed that the implementation of the Web-based information system about infection prevention and control in hospital A decreased exposure incidents with BBFs among the HCWs (P < .001).

  15. Critical windows of exposure for children's health: cancer in human epidemiological studies and neoplasms in experimental animal models.

    PubMed Central

    Anderson, L M; Diwan, B A; Fear, N T; Roman, E

    2000-01-01

    In humans, cancer may be caused by genetics and environmental exposures; however, in the majority of instances the identification of the critical time window of exposure is problematic. The evidence for exposures occurring during the preconceptional period that have an association with childhood or adulthood cancers is equivocal. Agents definitely related to cancer in children, and adulthood if exposure occurs in utero, include: maternal exposure to ionizing radiation during pregnancy and childhood leukemia and certain other cancers, and maternal use of diethylstilbestrol during pregnancy and clear-cell adenocarcinoma of the vagina of their daughters. The list of environmental exposures that occur during the perinatal/postnatal period with potential to increase the risk of cancer is lengthening, but evidence available to date is inconsistent and inconclusive. In animal models, preconceptional carcinogenesis has been demonstrated for a variety of types of radiation and chemicals, with demonstrated sensitivity for all stages from fetal gonocytes to postmeiotic germ cells. Transplacental and neonatal carcinogenesis show marked ontogenetic stage specificity in some cases. Mechanistic factors include the number of cells at risk, the rate of cell division, the development of differentiated characteristics including the ability to activate and detoxify carcinogens, the presence of stem cells, and possibly others. Usefulness for human risk estimation would be strengthened by the study of these factors in more than one species, and by a focus on specific human risk issues. Images Figure 1 PMID:10852857

  16. Do hunger and exposure to food affect scores on a measure of hedonic hunger? An experimental study.

    PubMed

    Witt, Ashley A; Raggio, Greer A; Butryn, Meghan L; Lowe, Michael R

    2014-03-01

    Research suggests that visceral bodily states, such as hunger, can affect participants' responses on self-report measures of eating behavior. The present study evaluated the influence of hunger and exposure to palatable food on self-reported hedonic appetite, measured using the Power of Food Scale (PFS). A secondary aim was to evaluate the effects of these manipulations on self-reported external eating and disinhibition. Participants (N=67) ate a standardized meal followed by a 4-h fast. Participants were randomized to one of four groups (Fasted/Food Absence, Fasted/Food Exposure, Fed/Food Absence, or Fed/Food Exposure). In Phase I of the experiment (Hunger Manipulation), participants randomized to the "Fed" group drank a protein shake, while those in the "Fasted" group did not receive a shake. In Phase II (Palatable Food Exposure), participants in the "Food Exposure" group were visually exposed to palatable food items, while "Food Absence" participants were not. All participants completed the PFS, Dutch Eating Behavior Questionnaire External Eating subscale, and the Disinhibition subscale from the Eating Inventory during Phase II. Results showed no significant main or interactive effects of Hunger condition or Food Exposure condition on PFS, External Eating, or Disinhibition scores (all p's<.33). All effect sizes were small (partial etas squared ⩽.015). Manipulation checks confirmed that the intended hunger and exposure interventions were successful. Results suggest that relatively short fasting periods (e.g., 4h) analogous to typical breaks between meals are not associated with changes in scores on the PFS, External Eating, or Disinhibition scales. Hedonic hunger, at least as measured by the PFS, may represent a relatively stable construct that is not substantially affected by daily variations in hunger. In addition, individual differences in exposure to food in the immediate environment are unlikely to confound research using these measures.

  17. Experimental strategy for translational studies of organophosphorus pesticide neurotoxicity based on real-world occupational exposures to chlorpyrifos

    PubMed Central

    Lein, Pamela J.; Bonner, Matthew R.; Farahat, Fayssal M.; Olson, James R.; Rohlman, Diane S.; Fenske, Richard A.; Lattal, K. Matthew; Lasarev, Michael R.; Galvin, Kit; Farahat, Taghreed M.; Anger, W. Kent

    2012-01-01

    Translational research is needed to understand and predict the neurotoxic consequences associated with repeated occupational exposures to organophosphorus pesticides (OPs). In this report, we describe a research strategy for identifying biomarkers of OP neurotoxicity, and we characterize pesticide application workers in Egypt’s Menoufia Governorate who serve as our anchor human population for developing a parallel animal model with similar exposures and behavioral deficits and for examining the influence of human polymorphisms in cytochrome P450 (CYP) and paraoxonase 1 (PON1) enzymes on OP metabolism and toxicity. This population has previously been shown to have high occupational exposures and to exhibit a broad range of neurobehavioral deficits. In addition to observational studies of work practices in the field, questionnaires on demographics, lifestyle and work practices were administered to 146 Egyptian pesticide application workers applying pesticides to the cotton crop. Survey results indicated that the application workforce uses standard operating procedures and standardized equipment provided by Egypt’s Ministry of Agriculture, which provides a workforce with a stable work history. We also found that few workers report using personal protective equipment (PPE), which likely contributes to the relatively high exposures reported in these application workers. In summary, this population provides a unique opportunity for identifying biomarkers of OP-induced neurotoxicity associated with occupational exposure. PMID:22240005

  18. Experimental strategy for translational studies of organophosphorus pesticide neurotoxicity based on real-world occupational exposures to chlorpyrifos.

    PubMed

    Lein, Pamela J; Bonner, Matthew R; Farahat, Fayssal M; Olson, James R; Rohlman, Diane S; Fenske, Richard A; Lattal, K Matthew; Lasarev, Michael R; Galvin, Kit; Farahat, Taghreed M; Anger, W Kent

    2012-08-01

    Translational research is needed to understand and predict the neurotoxic consequences associated with repeated occupational exposures to organophosphorus pesticides (OPs). In this report, we describe a research strategy for identifying biomarkers of OP neurotoxicity, and we characterize pesticide application workers in Egypt's Menoufia Governorate who serve as our anchor human population for developing a parallel animal model with similar exposures and behavioral deficits and for examining the influence of human polymorphisms in cytochrome P450 (CYP) and paraoxonase 1 (PON1) enzymes on OP metabolism and toxicity. This population has previously been shown to have high occupational exposures and to exhibit a broad range of neurobehavioral deficits. In addition to observational studies of work practices in the field, questionnaires on demographics, lifestyle and work practices were administered to 146 Egyptian pesticide application workers applying pesticides to the cotton crop. Survey results indicated that the application workforce uses standard operating procedures and standardized equipment provided by Egypt's Ministry of Agriculture, which provides a workforce with a stable work history. We also found that few workers report using personal protective equipment (PPE), which likely contributes to the relatively high exposures reported in these application workers. In summary, this population provides a unique opportunity for identifying biomarkers of OP-induced neurotoxicity associated with occupational exposure.

  19. Cardiac Repolarization and Autonomic Regulation during Short-Term Cold Exposure in Hypertensive Men: An Experimental Study

    PubMed Central

    Hintsala, Heidi; Kenttä, Tuomas V.; Tulppo, Mikko; Kiviniemi, Antti; Huikuri, Heikki V.; Mäntysaari, Matti; Keinänen-Kiukaannemi, Sirkka; Bloigu, Risto; Herzig, Karl-Heinz; Antikainen, Riitta; Rintamäki, Hannu; Jaakkola, Jouni J. K.; Ikäheimo, Tiina M.

    2014-01-01

    Objectives The aim of our study was to assess the effect of short-term cold exposure, typical in subarctic climate, on cardiac electrical function among untreated middle-aged hypertensive men. Methods We conducted a population-based recruitment of 51 hypertensive men and a control group of 32 men without hypertension (age 55–65 years) who underwent whole-body cold exposure (15 min exposure to temperature −10°C, wind 3 m/s, winter clothes). Conduction times and amplitudes, vectorcardiography, arrhythmias, and heart rate variability (autonomic nervous function) were assessed. Results Short-term cold exposure increased T-peak to T-end interval from 67 to 72 ms (p<0.001) and 71 to 75 ms (p<0.001) and T-wave amplitude from 0.12 to 0.14 mV (p<0.001) and from 0.17 to 0.21 mV (p<0.001), while QTc interval was shortened from 408 to 398 ms (p<0.001) and from 410 to 401 ms (p<0.001) among hypertensive men and controls, respectively. Cold exposure increased both low (from 390 to 630 ms2 (p<0.001) and 380 to 700 ms2 (p<0.001), respectively) and high frequency heart rate variability (from 90 to 190 ms2 (p<0.001) and 150 to 300 ms2 (p<0.001), respectively), while low-to-high frequency-ratio was reduced. In addition, the frequency of ventricular ectopic beats increased slightly during cold exposure. The cold induced changes were similar between untreated hypertensive men and controls. Conclusions Short-term cold exposure with moderate facial and mild whole body cooling resulted in prolongation of T-peak to T-end interval and higher T-wave amplitude while QTc interval was shortened. These changes of ventricular repolarization may have resulted from altered cardiac autonomic regulation and were unaffected by untreated hypertension. Trial Registration ClinicalTrials.gov NCT02007031 PMID:24983379

  20. Exposure to hydrogen fluoride: an experimental study in humans of concentrations of fluoride in plasma, symptoms, and lung function.

    PubMed Central

    Lund, K; Ekstrand, J; Boe, J; Søstrand, P; Kongerud, J

    1997-01-01

    OBJECTIVES: To study the absorption of inhaled hydrogen fluoride (HF) by measuring plasma fluorides and HF concentrations in the breathing zone during exposure to HF. A possible dose-effect relation was investigated by following airway symptoms and lung function-that is, forced expiratory volume in one second (FEV1) and forced vital capacity (FVC)-during and after exposure to HF. METHODS: 20 healthy, male volunteers were exposed for one hour to constant HF concentrations that ranged from 0.2 to 5.2 mg/m3; these concentrations are known to occur among potroom workers in the primary aluminium industry. Plasma fluorides were analysed before, during, and after exposure. Symptoms from the eyes and the upper and lower airways were registered and graded from 1 to 5 with a standardised questionnaire. RESULTS: The total symptom score was significantly increased at the end of exposure for all the subjects as a group (P < 0.01) and for the group exposed to HF below the present Norwegian standard for total fluorides 0.6 mg/m3 (P = 0.05). No change was detected in FEV15 although a significant decrease was found in FVC in the group exposed to fluorides below the hygienic standard (n = 9) and for the entire group (n = 23). Almost all the symptoms had disappeared four hours after the end of exposure. Symptom scores from the upper airways were significantly correlated with the HF concentration (r = 0.62, P = 0.002), the change in plasma fluoride concentration (delta C) (r = 0.51, P = 0.01), and the maximum plasma fluoride concentration (Cmax) (r = 0.42, P = 0.05). A significant correlation was also found between the total symptom score for airways and the HF concentration. CONCLUSIONS: The present study showed a strong relation between inhaled HF and concentrations of fluoride in plasma. Upper airway and eye symptoms occurred after one hour of exposure to HF even when below the Norwegian hygienic standard for fluorides. PMID:9072031

  1. Mercury Reduces Avian Reproductive Success and Imposes Selection: An Experimental Study with Adult- or Lifetime-Exposure in Zebra Finch

    PubMed Central

    Varian-Ramos, Claire W.; Swaddle, John P.; Cristol, Daniel A.

    2014-01-01

    Mercury is a global pollutant that biomagnifies in food webs, placing wildlife at risk of reduced reproductive fitness and survival. Songbirds are the most diverse branch of the avian evolutionary tree; many are suffering persistent and serious population declines and we know that songbirds are frequently exposed to mercury pollution. Our objective was to determine the effects of environmentally relevant doses of mercury on reproductive success of songbirds exposed throughout their lives or only as adults. The two modes of exposure simulated philopatric species versus dispersive species, and are particularly relevant because of the heightened mercury-sensitivity of developing nervous systems. We performed a dosing study with dietary methylmercury in a model songbird species, the zebra finch (Taeniopygia guttata), at doses from 0.3 – 2.4 parts per million. Birds were exposed to mercury either as adults only or throughout their lives. All doses of mercury reduced reproductive success, with the lowest dose reducing the number of independent offspring produced in one year by 16% and the highest dose, representing approximately half the lethal dose for this species, causing a 50% reduction. While mercury did not affect clutch size or survivorship, it had the most consistent effect on the proportion of chicks that fledged from the nest, regardless of mode of exposure. Among birds exposed as adults, mercury caused a steep increase in the latency to re-nest after loss of a clutch. Birds exposed for their entire lifetimes, which were necessarily the offspring of dosed parents, had up to 50% lower reproductive success than adult-exposed birds at low doses of methylmercury, but increased reproductive success at high doses, suggesting selection for mercury tolerance at the highest level of exposure. Our results indicate that mercury levels in prey items at contaminated sites pose a significant threat to populations of songbirds through reduced reproductive success. PMID

  2. Mercury reduces avian reproductive success and imposes selection: an experimental study with adult- or lifetime-exposure in zebra finch.

    PubMed

    Varian-Ramos, Claire W; Swaddle, John P; Cristol, Daniel A

    2014-01-01

    Mercury is a global pollutant that biomagnifies in food webs, placing wildlife at risk of reduced reproductive fitness and survival. Songbirds are the most diverse branch of the avian evolutionary tree; many are suffering persistent and serious population declines and we know that songbirds are frequently exposed to mercury pollution. Our objective was to determine the effects of environmentally relevant doses of mercury on reproductive success of songbirds exposed throughout their lives or only as adults. The two modes of exposure simulated philopatric species versus dispersive species, and are particularly relevant because of the heightened mercury-sensitivity of developing nervous systems. We performed a dosing study with dietary methylmercury in a model songbird species, the zebra finch (Taeniopygia guttata), at doses from 0.3 - 2.4 parts per million. Birds were exposed to mercury either as adults only or throughout their lives. All doses of mercury reduced reproductive success, with the lowest dose reducing the number of independent offspring produced in one year by 16% and the highest dose, representing approximately half the lethal dose for this species, causing a 50% reduction. While mercury did not affect clutch size or survivorship, it had the most consistent effect on the proportion of chicks that fledged from the nest, regardless of mode of exposure. Among birds exposed as adults, mercury caused a steep increase in the latency to re-nest after loss of a clutch. Birds exposed for their entire lifetimes, which were necessarily the offspring of dosed parents, had up to 50% lower reproductive success than adult-exposed birds at low doses of methylmercury, but increased reproductive success at high doses, suggesting selection for mercury tolerance at the highest level of exposure. Our results indicate that mercury levels in prey items at contaminated sites pose a significant threat to populations of songbirds through reduced reproductive success.

  3. Exposure to alcohol commercials in movie theaters affects actual alcohol consumption in young adult high weekly drinkers: an experimental study.

    PubMed

    Koordeman, Renske; Anschutz, Doeschka J; Engels, Rutger C M E

    2011-01-01

    The present pilot study examined the effects of alcohol commercials shown in movie theaters on the alcohol consumption of young adults who see these commercials. A two (alcohol commercials vs. nonalcohol commercials) by two (high weekly alcohol consumption vs. low weekly alcohol consumption) between-participant design was used, in which 184 young adults (age: 16-28 years) were exposed to a movie that was preceded by either alcohol commercials or nonalcohol commercials. Participants' actual alcohol consumption while watching the movie ("Watchmen") was examined. An analysis of variance (ANOVA) was conducted to examine the effects of the commercial condition on alcohol consumption. An interaction effect was found between commercial condition and weekly alcohol consumption (p < .001). Alcohol consumption among high weekly alcohol drinkers was higher in the alcohol commercial condition than in the nonalcohol commercial condition, whereas no differences were found in alcohol consumption between commercial conditions among low weekly alcohol drinkers. No gender differences were found in the association between exposure to alcohol commercials, weekly drinking, and alcohol use. Thus, exposure to alcohol commercials prior to a movie in a movie theater can directly influence alcohol consumption among high weekly alcohol consumers. © American Academy of Addiction Psychiatry.

  4. Correlation between Prenatal Exposure to Polybrominated Diphenyl Ethers (PBDEs) and Infant Birth Outcomes: A Meta-Analysis and an Experimental Study

    PubMed Central

    Zhao, Xuemin; Peng, Shiqiao; Xiang, Yang; Yang, Yali; Li, Jing; Shan, Zhongyan; Teng, Weiping

    2017-01-01

    Only a few epidemiological studies have focused on the correlation between prenatal exposure to polybrominated diphenyl ethers (PBDEs) and infant birth outcomes (IBO), and the results of these epidemiological studies are contradictory. The objective of this study was to assess the correlation between prenatal exposure to PBDEs (PEP) and IBO (i.e., birth weight) in an analysis of epidemiological studies and an experimental animals study. We searched databases of the medical literature (PubMed, Excerpta Medica Database, Cochrane Library, and China National Knowledge Infrastructure) for articles and pooled the results of the included epidemiological studies. In parallel, birth outcomes (i.e., birth weights of pups) were collected from female Sprague-Dawley (SD) rats exposed to decabromodiphenyl ether (DecaBDE) in the diet from five weeks of age to delivery. A significant negative relationship was found between human PBDE burden and birth weight in the analysis of seven epidemiological studies based on a random-effects model (β = −50.598; 95% confidence interval (CI) −95.914, −5.282; I2 = 11.8%; p = 0.029). In the experimental animal study, a significant decrease in birth weight in the DecaBDE-treated group was also observed (5.26 ± 0.39 vs. 5.8 ± 0.58, p = 0.0132). The results of our study contribute to increasing evidence suggesting that PEP adversely impacts IBO, especially birth weight. PMID:28272363

  5. IMMUNOASSAY HUMAN EXPOSURE STUDIES

    EPA Science Inventory

    The Human Exposure Research Branch has developed several enzyme-linked immunosorbent assay (ELISA) methods to support human exposure assessment studies. Immunoassays to detect low levels (<10 ng/mL) of chlorpyrifos in food, track-in dirt and house dust have been applied to sam...

  6. IMMUNOASSAY HUMAN EXPOSURE STUDIES

    EPA Science Inventory

    The Human Exposure Research Branch has developed several enzyme-linked immunosorbent assay (ELISA) methods to support human exposure assessment studies. Immunoassays to detect low levels (<10 ng/mL) of chlorpyrifos in food, track-in dirt and house dust have been applied to sam...

  7. The effects of rumination on mood and intrusive memories after exposure to traumatic material: An experimental study

    PubMed Central

    Zetsche, Ulrike; Ehring, Thomas; Ehlers, Anke

    2009-01-01

    Correlational studies have shown that trauma-related rumination predicts chronic post-traumatic stress disorder (PTSD). This study aimed to experimentally test the hypothesis that rumination is causally involved in the development and maintenance of PTSD symptoms. A video depicting the aftermath of serious road traffic accidents was used as an analogue stressor. After having watched the video, N = 101 healthy participants were randomly assigned to a guided thinking task designed to induce (a) rumination, (b) memory integration and (c) distraction. In line with the hypotheses, rumination led to less recovery from sad mood triggered by the video than the other two conditions. In addition, self-reported state levels of rumination during the guided thinking task predicted subsequent intrusive memories in the session. However, no significant main effect of the experimental manipulation on intrusive memories of the video was found. Results of exploratory analyses suggested possible sex differences in the way the processing manipulations were effective. Taken together, the results partially support the hypothesis that rumination is involved in the maintenance of negative mood and post-traumatic stress symptoms. PMID:19665693

  8. Early life exposure to artificial light at night affects the physiological condition: An experimental study on the ecophysiology of free-living nestling songbirds.

    PubMed

    Raap, Thomas; Casasole, Giulia; Pinxten, Rianne; Eens, Marcel

    2016-11-01

    Light pollution or artificial light at night (ALAN) is increasingly recognised to be an important anthropogenic environmental pressure on wildlife, affecting animal behaviour and physiology. Early life experiences are extremely important for the development, physiological status and health of organisms, and as such, early exposure to artificial light may have detrimental consequences for organism fitness. We experimentally manipulated the light environment of free-living great tit nestlings (Parus major), an important model species in evolutionary and environmental research. Haptoglobin (Hp) and nitric oxide (NOx), as important indicators of immunity, health, and physiological condition, were quantified in nestlings at baseline (13 days after hatching) and after a two night exposure to ALAN. We found that ALAN increased Hp and decreased NOx. ALAN may increase stress and oxidative stress and reduce melatonin which could subsequently lead to increased Hp and decreased NOx. Haptoglobin is part of the immune response and mounting an immune response is costly in energy and resources and, trade-offs are likely to occur with other energetically demanding tasks, such as survival or reproduction. Acute inhibition of NOx may have a cascading effect as it also affects other physiological aspects and may negatively affect immunocompetence. The consequences of the observed effects on Hp and NOx remain to be examined. Our study provides experimental field evidence that ALAN affects nestlings' physiology during development and early life exposure to ALAN could therefore have long lasting effects throughout adulthood.

  9. Biliary ochratoxin A as a biomarker of ochratoxin exposure in laying hens: An experimental study after administration of contaminated diets.

    PubMed

    Armorini, Sara; Al-Qudah, Khaled Mefleh; Altafini, Alberto; Zaghini, Anna; Roncada, Paola

    2015-06-01

    To evaluate the levels of ochratoxin (OTA) in kidney, liver and bile of laying hens, forty-five laying hens were enrolled in this study and divided into three equal groups: a control group D₀, and two experimental groups, D₁ fed with 10 µg/kg OTA diet and D₂ fed with 200 µg/kg OTA diet for 6 weeks. Kidneys, livers, and bile from all hens were collected and analyzed by HPLC method for the presence of OTA. Eggs collected 2 days before the start of the experiment and 2 days after its end were also analyzed for the presence of OTA. Results show a relevant biliary excretion of the mycotoxin, with high levels of OTA in the bile after administration of the toxin. OTA level in eggs was below the limit of detection (LOD). These results suggest the suitability of using bile as a matrix for screening measurements of OTA in laying hens.

  10. Experimental exposure of cattle to a precise aerosolised challenge of Mycobacterium bovis: a novel model to study bovine tuberculosis.

    PubMed

    Rodgers, J D; Connery, N L; McNair, J; Welsh, M D; Skuce, R A; Bryson, D G; McMurray, D N; Pollock, J M

    2007-09-01

    Non-aerosol models of bovine tuberculosis are limited in reproducibility and relevance to natural cases seen in farmed animals. Therefore, there is a need for aerosol models of infection in cattle that can reproduce bovine tuberculosis as seen in natural cases of the disease. This manuscript describes a cattle tuberculosis model based on the inhalation of a precisely defined dose of Mycobacterium bovis in aerosol form, and defines those sites of M. bovis deposition following aerosol inhalation. The dissemination of bacilli and the resultant pathological change following infection is also described. Cattle aged 4-5 months, were infected with approximately 10(4) colony forming units (CFU), using a Madison chamber that had been modified to deliver aerosols to calves. In Experiment 1, calves were examined for gross pathology at post mortem (PM) examination at 93 and 132 days post-infection (PI), respectively. In Experiment 2, pairs of calves were examined for gross pathology at PM examination at 1 day PI and 7 days PI, respectively. At PM examination, samples were taken for bacteriology. Retrospective counts showed that the calves inhaled between 3 x 10(4) and 8 x 10(4)CFU of M. bovis. In Experiment 1, pathology indicative of tuberculosis and detection of M. bovis by qualitative bacteriology was found throughout the lower respiratory tract (LRT). In Experiment 2, pathology was only observed in a single site of one calf at day 7 PI. Samples positive for M. bovis by bacteriology were predominantly in the LRT. The numbers of M. bovis CFU recovered and the distributions of positive sites were greater at day 7 PI than day 1 PI. This study describes an aerosol exposure method that can deliver a defined dose of M. bovis almost exclusively to the LRT. The distribution of M. bovis and lesions indicative of tuberculosis suggests this aerosol method replicates the primary mode of tuberculosis transmission in cattle.

  11. Eggshell Appearance Does Not Signal Maternal Corticosterone Exposure in Japanese Quail: An Experimental Study with Brown-Spotted Eggs

    PubMed Central

    Duval, Camille; Cassey, Phillip; Lovell, Paul G.; Mikšík, Ivan; Reynolds, S. James; Spencer, Karen A.

    2013-01-01

    Reproduction is a critical period for birds as they have to cope with many stressful events. One consequence of an acute exposure to stress is the release of corticosterone, the avian stress hormone. Prolonged stress can have negative impacts on the immune system, resulting in, for example, increased oxidative stress. Through maternal effects, females are known to modulate their investment in eggs content according to their own physiological condition. Less is known about maternal investment in eggshells, especially in pigments. The two main eggshell pigments may possess opposite antioxidant properties: protoporphyrin (brown) is a pro-oxidant, whereas biliverdin (blue-green) is an antioxidant. In Japanese quail, we know that the deposition of both pigments is related to female body condition. Thus, a chronic stress response may be reflected in eggshell coloration. Using female Japanese quails that lay brown-spotted eggs, we explored whether physiological exposure to corticosterone induces a change in female basal stress and antioxidant factors, and eggshell pigment concentration, spectrophotometric reflectance, and maculation coverage. We supplemented adult females over a 2 week period with either peanut oil (control) or corticosterone (treatment). We collected pre- and post-supplementation eggs and analysed the effect of corticosterone treatment on female physiology and eggshell appearance parameters. Except for corticosterone-fed birds which laid eggs with brighter spots, supplementation had no significant effect on female physiology or eggshell pigment concentration, reflectance and maculation. The change in eggshell spot brightness was not detected by a photoreceptor noise-limited color opponent model of avian visual perception. Our data confirms that eggshell reflectance in spotted eggs varies over the laying sequence, and spot reflectance may be a key factor that is affected by females CORT exposure, even if the changes are not detected by an avian visual

  12. Eggshell appearance does not signal maternal corticosterone exposure in Japanese quail: an experimental study with brown-spotted eggs.

    PubMed

    Duval, Camille; Cassey, Phillip; Lovell, Paul G; Mikšík, Ivan; Reynolds, S James; Spencer, Karen A

    2013-01-01

    Reproduction is a critical period for birds as they have to cope with many stressful events. One consequence of an acute exposure to stress is the release of corticosterone, the avian stress hormone. Prolonged stress can have negative impacts on the immune system, resulting in, for example, increased oxidative stress. Through maternal effects, females are known to modulate their investment in eggs content according to their own physiological condition. Less is known about maternal investment in eggshells, especially in pigments. The two main eggshell pigments may possess opposite antioxidant properties: protoporphyrin (brown) is a pro-oxidant, whereas biliverdin (blue-green) is an antioxidant. In Japanese quail, we know that the deposition of both pigments is related to female body condition. Thus, a chronic stress response may be reflected in eggshell coloration. Using female Japanese quails that lay brown-spotted eggs, we explored whether physiological exposure to corticosterone induces a change in female basal stress and antioxidant factors, and eggshell pigment concentration, spectrophotometric reflectance, and maculation coverage. We supplemented adult females over a 2 week period with either peanut oil (control) or corticosterone (treatment). We collected pre- and post-supplementation eggs and analysed the effect of corticosterone treatment on female physiology and eggshell appearance parameters. Except for corticosterone-fed birds which laid eggs with brighter spots, supplementation had no significant effect on female physiology or eggshell pigment concentration, reflectance and maculation. The change in eggshell spot brightness was not detected by a photoreceptor noise-limited color opponent model of avian visual perception. Our data confirms that eggshell reflectance in spotted eggs varies over the laying sequence, and spot reflectance may be a key factor that is affected by females CORT exposure, even if the changes are not detected by an avian visual

  13. [A comparative analysis of healing mandibular defects due to exposure to different plastic materials (experimental morphological study)].

    PubMed

    Fedorovskaya, L N; Grigor'ian, A S; Kulakov, A A; Khamraev, T K

    2001-01-01

    Autogenous bone grafts are the most effective factor able to activate osteogenesis in bone defects, as shown by our experiments. Experimental biomaterials such as Bio-Oss and KP-3 have a high osteogenesis potential, too. However the callus initiated in jaw defects by those biomaterials underwent partial reduction during secondary rebuilding, thus becoming a less authentic bone formation.

  14. Neurobehavioural effects of experimental isopropanol exposure.

    PubMed

    Sethre, T; Läubli, T; Berode, M; Krueger, H

    2000-03-01

    The study investigated the acute effects of isopropanol exposure at the maximum allowable concentration (MAC) level on the performance of neurobehavioural functions. In an exposure chamber 20 healthy subjects aged between 21 and 30 years were exposed to isopropanol at a concentration of 400 ppm (Swiss MAC value) for 8 h. A control group of another 20 subjects of the same age range, gender and education as used in a previous study with methylformate were subjected to the same test procedures without exposure. Mood was measured with the profile of mood states (POMS) in the morning, at noon and in the evening. Neurobehavioural performance tests were administered using the Wiener Test System (Wiener reaction test, Stroop, nonverbal learning, Wiener determination test, "Konturtracking" test), and the digit span test of the Neurobehavioural evaluation system (NES2). A test for postural sway was also conducted. During the POMS and the Wiener determination test the electromyography of the forehead and the left neck muscle as well as the pulse were registered. In the morning and evening spirometry (FVC, FEV, MEF and PEF) and odour threshold were measured. Only postural sway in bipedal standing at noon showed stronger deterioration in the exposed than in the control group when compared with the morning values. The evening values of monopedal standing were also more impaired in the exposed than the control group. In the other tests, no solvent effect could be established. It can be assumed, that, similar to other alcohols, isopropanol affects postural balance. Our results point to such a disturbance, but because it is the only study so far using the MAC value, any conclusions about safety risks would be premature.

  15. Minimizing the exposure of airborne pathogens by upper-room ultraviolet germicidal irradiation: an experimental and numerical study

    PubMed Central

    Yang, Y.; Chan, W. Y.; Wu, C. L.; Kong, R. Y. C.; Lai, A. C. K.

    2012-01-01

    There has been increasing interest in the use of upper-room ultraviolet germicidal irradiation (UVGI) because of its proven effectiveness in disinfecting airborne pathogens. An improved drift flux mathematical model is developed for optimizing the design of indoor upper-room UVGI systems by predicting the distribution and inactivation of bioaerosols in a ventilation room equipped with a UVGI system. The model takes into account several bacteria removal mechanisms such as convection, turbulent diffusion, deposition and UV inactivation. Before applying the model, the natural die-off rate and susceptibility constants of bioaerosols were measured experimentally. Two bacteria aerosols, Escherichia coli and Serratia marcescens, were tested for this purpose. It was found out that the general decay trend of the bioaerosol concentration predicted by the numerical model agrees well with the experimental measurements. The modelling results agree better with experimental observations for the case when the UVGI inactivation mechanism dominates at the upper-room region than for the case without UVGI. The numerical results also illustrate that the spatial distribution of airborne bacteria was influenced by both air-flow pattern and irradiance distribution. In addition to predicting the local variation of concentration, the model assesses the overall performance of an upper-room UVGI system. This model has great potential for optimizing the design of indoor an upper-room UVGI systems. PMID:22809847

  16. Evaporite Caprock Integrity. An experimental study of reactive mineralogy and pore-scale heterogeneity during brine-CO2 exposure

    DOE PAGES

    Smith, Megan M.; Sholokhova, Yelena; Hao, Yue; ...

    2012-07-25

    Characterization and geochemical data are presented from a core-flooding experiment on a sample from the Three Fingers evaporite unit forming the lower extent of caprock at the Weyburn-Midale reservoir, Canada. This low-permeability sample was characterized in detail using X-ray computed microtomography before and after exposure to CO 2-acidified brine, allowing mineral phase and voidspace distributions to be quantified in three dimensions. Solution chemistry indicated that CO 2-acidified brine preferentially dissolved dolomite until saturation was attained, while anhydrite remained unreactive. Dolomite dissolution contributed to increases in bulk permeability through the formation of a localized channel, guided by microfractures as well asmore » porosity and reactive phase distributions aligned with depositional bedding. An indirect effect of carbonate mineral reactivity with CO 2-acidified solution is voidspace generation through physical transport of anhydrite freed from the rock matrix following dissolution of dolomite. The development of high permeability fast pathways in this experiment highlights the role of carbonate content and potential fracture orientations in evaporite caprock formations considered for both geologic carbon sequestration and CO 2-enhanced oil recovery operations.« less

  17. Evaporite caprock integrity: an experimental study of reactive mineralogy and pore-scale heterogeneity during brine-CO2 exposure.

    PubMed

    Smith, Megan M; Sholokhova, Yelena; Hao, Yue; Carroll, Susan A

    2013-01-02

    We present characterization and geochemical data from a core-flooding experiment on a sample from the Three Fingers evaporite unit forming the lower extent of caprock at the Weyburn-Midale reservoir, Canada. This low-permeability sample was characterized in detail using X-ray computed microtomography before and after exposure to CO(2)-acidified brine, allowing mineral phase and voidspace distributions to be quantified in three dimensions. Solution chemistry indicated that CO(2)-acidified brine preferentially dissolved dolomite until saturation was attained, while anhydrite remained unreactive. Dolomite dissolution contributed to increases in bulk permeability through the formation of a localized channel, guided by microfractures as well as porosity and reactive phase distributions aligned with depositional bedding. An indirect effect of carbonate mineral reactivity with CO(2)-acidified solution is voidspace generation through physical transport of anhydrite freed from the rock matrix following dissolution of dolomite. The development of high permeability fast pathways in this experiment highlights the role of carbonate content and potential fracture orientations in evaporite caprock formations considered for both geologic carbon sequestration and CO(2)-enhanced oil recovery operations.

  18. Looking for boomerang effects: a pre-post experimental study of the effects of exposure of youth to television advertising for nicotine replacement therapy and Zyban.

    PubMed

    Durkin, Sarah; Wakefield, Melanie; Spittal, Matt

    2006-12-01

    In the context of concerns about unintended "boomerang" influences of advertising, this study aimed to examine effects of nicotine replacement therapy (NRT) and Zyban advertising on youth perceptions of the ease of quitting, health risks of smoking and future intentions to smoke. 718 youth aged 14-16years were randomly allocated to view four television ads promoting either: NRT; Zyban; non-pharmaceutical cessation services (telephone Quitline); or non-cessation messages on sun protection. Questionnaire measures were administered before and after viewing ads. There were no effects of advertising exposure on perceived health effects of smoking or intentions to smoke. Compared with the sun protection ads, but not the Quitline ads, those exposed to NRT ads reported stronger perceptions about the ease of quitting, but non-susceptible non-smokers primarily drove this difference. This study suggests that exposure to NRT and Zyban advertising in an experimental context does not reliably influence youth smoking-related beliefs, especially those vulnerable to becoming regular smokers.

  19. Subchronic Toluene Exposure alters Retinal Function in Long Evans Rats: Experimental Evidence Supporting Observations from Studies of Exposed Humans.

    EPA Science Inventory

    Studies of humans chronically exposed to volatile organic solvents commonly report impaired visual functions, including low contrast sensitivity and reduced color discrimination. These reports have been controversial, however, in part due to a lack of confirmation from controlled...

  20. ELECTRORETINOGRAMS ARE ALTERED BY SUBCHRONIC TOLUENE EXPOSURE TO LONG EVANS RATS: EXPERIMENTAL EVIDENCE SUPPORTING OBSERVATIONS FROM STUDIES OF EXPOSED HUMANS

    EPA Science Inventory

    Impaired visual functions, including low contrast sensitivity and reduced color discrimination, have been reported in studies of humans chronically exposed to several volatile organic solvents. These reports remain controversial, however, in part due to a lack of confirmation fro...

  1. Subchronic Toluene Exposure alters Retinal Function in Long Evans Rats: Experimental Evidence Supporting Observations from Studies of Exposed Humans.

    EPA Science Inventory

    Studies of humans chronically exposed to volatile organic solvents commonly report impaired visual functions, including low contrast sensitivity and reduced color discrimination. These reports have been controversial, however, in part due to a lack of confirmation from controlled...

  2. ELECTRORETINOGRAMS ARE ALTERED BY SUBCHRONIC TOLUENE EXPOSURE TO LONG EVANS RATS: EXPERIMENTAL EVIDENCE SUPPORTING OBSERVATIONS FROM STUDIES OF EXPOSED HUMANS

    EPA Science Inventory

    Impaired visual functions, including low contrast sensitivity and reduced color discrimination, have been reported in studies of humans chronically exposed to several volatile organic solvents. These reports remain controversial, however, in part due to a lack of confirmation fro...

  3. Prediction of experimental data for an independent variable using the experimental data collected for other independent variables in a study of skin cancer caused by exposure to UV radiation.

    PubMed

    Hashemi, Ray R; Bahar, Mahmood; Tang, Nan; Tyler, Alexander A; Hinson, William

    2003-05-01

    In this study, two algorithms (ONE and TWO) are introduced to determine the position of the t-distribution of variable V(i) (with 95% confidence) in the treated group in reference to the t-distribution of variable V(i) (with 95% confidence) in the control group of an experimental study involving UV radiation exposure of a group of rodents. The outcome of applying the two algorithms is two discretized files. A reduct of each file is generated using the rough sets methodology and then the measurements for one independent variable are predicted using the measurements of the other independent variables in the same reduct. The rough sets methodology and the fuzzy-rough classifier are used for this prediction. The results reveal that (1) algorithm TWO is the best, (2) the values for non-core variables are predicted with minimum accuracy of 87%, and (3) the prediction of values for core variables is not successful.

  4. Effects of artificial light at night on human health: A literature review of observational and experimental studies applied to exposure assessment.

    PubMed

    Cho, YongMin; Ryu, Seung-Hun; Lee, Byeo Ri; Kim, Kyung Hee; Lee, Eunil; Choi, Jaewook

    2015-01-01

    It has frequently been reported that exposure to artificial light at night (ALAN) may cause negative health effects, such as breast cancer, circadian phase disruption and sleep disorders. Here, we reviewed the literature assessing the effects of human exposure to ALAN in order to list the health effects of various aspects of ALAN. Several electronic databases were searched for articles, published through August 2014, related to assessing the effects of exposure to ALAN on human health; these also included the details of experiments on such exposure. A total of 85 articles were included in the review. Several observational studies showed that outdoor ALAN levels are a risk factor for breast cancer and reported that indoor light intensity and individual lighting habits were relevant to this risk. Exposure to artificial bright light during the nighttime suppresses melatonin secretion, increases sleep onset latency (SOL) and increases alertness. Circadian misalignment caused by chronic ALAN exposure may have negative effects on the psychological, cardiovascular and/or metabolic functions. ALAN also causes circadian phase disruption, which increases with longer duration of exposure and with exposure later in the evening. It has also been reported that shorter wavelengths of light preferentially disturb melatonin secretion and cause circadian phase shifts, even if the light is not bright. This literature review may be helpful to understand the health effects of ALAN exposure and suggests that it is necessary to consider various characteristics of artificial light, beyond mere intensity.

  5. Experimental study and evaluation of radioprotective drugs

    NASA Technical Reports Server (NTRS)

    Smith, D. E.; Thomson, J. F.

    1968-01-01

    Experimental study evaluates radioprotective drugs administered before exposure either orally or intravenously. Specifically studied are the sources of radiation, choice of radiation dose, choice of animals, administration of drugs, the toxicity of protective agents and types of protective drug.

  6. Experimental exposure to methylformate and its neurobehavioral effects.

    PubMed

    Sethre, T; Läubli, T; Berode, M; Hangartner, M; Krueger, H

    2000-08-01

    The aim of the study was to investigate the acute effects of experimental methylformate exposure on the nervous system. In an exposure chamber, 20 subjects were exposed to methylformate at 100 ppm [Swiss maximum allowable concentration (MAC)] for 8 h. The same number of subjects with the same ages (between 20 and 30 years), gender and education level (university) were examined by the same procedure as a control group. The subjects did not know if they were exposed or not. Three times (morning, noon, evening) during these 8 h, mood [Profile of Mood States (POMS)], neurobehavioral performance (reaction, Stroop, nonverbal learning, determination, tracking; Wiener Test System), vision (visual acuity, contrast sensitivity, color sensitivity) and postural sway were tested. During an undemanding test (POMS) and a demanding performance task (determination test), pulse, electromyography (EMG) of the forehead and of the neck were recorded. In the morning and evening spirometry [forced vital capacity (FVC), forced one-second expiration volume (FEV), medium expiration flow (MEF) and peak expiration flow (PEF)] and the odor perception threshold were measured. In the evening, in the exposed group, fatigue was significantly increased and the EMG of the forehead during a demanding task showed a different development during exposure. The other tests showed no significant solvent effect, but 16 of 43 test parameters showed a significant effect of time. The results of this study indicate a possible effect of methylformate exposure on the subjective feeling of fatigue after 8 h exposure at 100 ppm in young and healthy subjects, without measurable impairment of neurobehavioral performance. We assume that a similar effect in normal work, combined with a heavy workload and shift work, can lead to an impairment of productivity, and increase the risk of accidents.

  7. Effects of exposure of youths at risk for smoking to television advertising for nicotine replacement therapy and Zyban: an experimental study.

    PubMed

    Wakefield, Melanie; Durrant, Russil

    2006-01-01

    Television advertising for nicotine replacement therapy (NRT) and Zyban exposes the entire population, including adolescents, to persuasive messages about these smoking-cessation products. There is a risk that adolescents exposed to the advertising might underestimate addictiveness or perceive an unintended message that it is easy to quit smoking. This is of concern because optimism about quitting is a major predictor of trial and progression to heavier smoking among youths. We randomly allocated 492 youths age 12 to 14 years to one of three viewing conditions in which they viewed either (a) 4 NRT ads, (b) 4 Zyban ads, or (c) 4 ads promoting nonpharmacologic cessation services, such as telephone quitlines. After viewing each ad twice, participants completed a 1-page rating form. After all ads had been viewed, youths completed a questionnaire that measured intentions to smoke in the future, perceived addictiveness of smoking, perceived risks and benefits of smoking, and perceived need for pharmaceutical products and services. There were no differences in the composition of groups by age, gender, or smoking uptake. Youths were more likely to agree that the NRT and Zyban ads, compared with the quitline ads, made it seem easy to quit smoking (p < .001). However, there were no systematic differences between groups in perceived addictiveness of smoking, intentions to smoke, or other outcomes. This study suggests that although ads for NRT and Zyban may create "face value" impressions that it is easier to quit, at least in an experimental context in which exposure to ads for telephone quitlines is equal, such appraisals do not undermine more enduring perceptions about smoking. Field research taking into account the relatively high volume of pharmaceutical cessation product advertising is needed.

  8. A far-field radio-frequency experimental exposure system with unrestrained mice.

    PubMed

    Hansen, Jared W; Asif, Sajid; Singelmann, Lauren; Khan, Muhammad Saeed; Ghosh, Sumit; Gustad, Tom; Doetkott, Curt; Braaten, Benjamin D; Ewert, Daniel L

    2015-01-01

    Many studies have been performed on exploring the effects of radio-frequency (RF) energy on biological function in vivo. In particular, gene expression results have been inconclusive due, in part, to a lack of a standardized experimental procedure. This research describes a new far field RF exposure system for unrestrained murine models that reduces experimental error. The experimental procedure includes the materials used, the creation of a patch antenna, the uncertainty analysis of the equipment, characterization of the test room, experimental equipment used and setup, power density and specific absorption rate experiment, and discussion. The result of this research is an experimental exposure system to be applied to future biological studies.

  9. An experimental investigation on thermal exposure during bone drilling.

    PubMed

    Lee, Jueun; Ozdoganlar, O Burak; Rabin, Yoed

    2012-12-01

    This study presents an experimental investigation of the effects of spindle speed, feed rate, and depth of drilling on the temperature distribution during drilling of the cortical section of the bovine femur. In an effort to reduce measurement uncertainties, a new approach for temperature measurements during bone drilling is presented in this study. The new approach is based on a setup for precise positioning of multiple thermocouples, automated data logging system, and a computer numerically controlled (CNC) machining system. A battery of experiments that has been performed to assess the uncertainty and repeatability of the new approach displayed adequate results. Subsequently, a parametric study was conducted to determine the effects of spindle speed, feed rate, hole depth, and thermocouple location on the measured bone temperature. This study suggests that the exposure time during bone drilling far exceeds the commonly accepted threshold for thermal injury, which may prevail at significant distances from the drilled hole. Results of this study suggest that the correlation of the thermal exposure threshold for bone injury and viability should be further explored.

  10. Writing in Kindergarten Classrooms: A Report of an Experimental Study of the Effects of Independent Writing Time and Exposure to a Writing Role Model on Selected Kindergarten Children.

    ERIC Educational Resources Information Center

    Holmes, Julia Goolsby

    A study examined whether there were any differences in the concepts about print, writing vocabulary, and prereading performance of selected kindergarten children who were provided with (1) independent writing time and exposure to a writing model in the school environment, (2) independent writing time without the writing role model, and (3) neither…

  11. Writing in Kindergarten Classrooms: A Report of an Experimental Study of the Effects of Independent Writing Time and Exposure to a Writing Role Model on Selected Kindergarten Children.

    ERIC Educational Resources Information Center

    Holmes, Julia Goolsby

    A study examined whether there were any differences in the concepts about print, writing vocabulary, and prereading performance of selected kindergarten children who were provided with (1) independent writing time and exposure to a writing model in the school environment, (2) independent writing time without the writing role model, and (3) neither…

  12. Magnetohydrodynamic generator experimental studies

    NASA Technical Reports Server (NTRS)

    Pierson, E. S.

    1972-01-01

    The results for an experimental study of a one wavelength MHD induction generator operating on a liquid flow are presented. First the design philosophy and the experimental generator design are summarized, including a description of the flow loop and instrumentation. Next a Fourier series method of treating the fact that the magnetic flux density produced by the stator is not a pure traveling sinusoid is described and some results summarized. This approach appears to be of interest after revisions are made, but the initial results are not accurate. Finally, some of the experimental data is summarized for various methods of excitation.

  13. AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY

    EPA Science Inventory

    The Agricultural Health Study (AHS) is a prospective epidemiologic study of a large cohort of pesticide applicators and their spouses in Iowa and North Carolina. The Pesticide Exposure Study is a sub-study to evaluate exposure factors and to provide data to assess exposure cla...

  14. AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY

    EPA Science Inventory

    The Agricultural Health Study (AHS) is a prospective epidemiologic study of a large cohort of pesticide applicators and their spouses in Iowa and North Carolina. The Pesticide Exposure Study is a sub-study to evaluate exposure factors and to provide data to assess exposure cla...

  15. Study protocol: psychological and physiological consequences of exposure to mass media in young women - an experimental cross-sectional and longitudinal study and the role of moderators.

    PubMed

    Munsch, Simone

    2014-01-01

    Repeated exposure to thin beauty ideals is part of the daily routine. Exposure to thin ideals via mass media plays an important role in the development and maintenance of eating disorders (EDs), low self-esteem, depressive or anxious feelings in young females. It is important to elucidate the circumstances under which exposure to thin ideals develops its detrimental impact and to investigate whether these features are more pronounced in EDs than in other mental disorders also related to negative body image. We investigate the following key questions: (1) Does laboratory induced exposure to thin ideals (waiting room design) relate to impairments in terms of body image, affect and eating behavior and biological stress response (salivary alpha-amylase, salivary cortisol, heart rate and heart rate variability) in 18 to 35 year old female suffering from anorexia and bulimia nervosa (AN, BN) compared to female healthy controls and to a sample of females suffering from mixed mental disorders (depression, anxiety and somatic symptom disorder (SSD) disorders)? (2) How do moderators such as cognitive distortions ("Thought-Shape Fusion, TSF"), and correlates of emotion regulation (ER) moderate the influence of the exposure? (3) Are these characteristics amenable to change after treatment? Altogether 250 female participants including patients with AN, BN, depressive, anxiety and SSD disorders, and healthy women will be recruited in Switzerland and Germany. The findings will provide knowledge about the role of moderators influencing the effects of exposure to thin ideals promoted by mass media in eating disorder (ED) patients, patients suffering from mixed mental disorders and healthy controls. Evaluating their differential susceptibility will contribute to a better understanding of the role of negative body image in the maintenance of not only symptoms of ED, but also of depression, anxiety and SSD. Additionally our results will shed light on the stability of effects in

  16. Exposure to cotton dust in an experimental cardroom.

    PubMed Central

    Haglind, P; Rylander, R

    1984-01-01

    Changes in respiratory function (FEV1) and polymorphonuclear neutrophils (PMN) on nasal epithelium were studied in 68 students and 39 cotton mill workers in an experimental cardroom. The exposure was characterised by the vertical elutriator dust and endotoxin levels. A dose related decrease was found for FEV1 which was more pronounced in smoking workers. The thresholds for no FEV1 reaction were 0.58 mg/m3 dust and 0.17 micrograms/m3 endotoxin for students and 0.43 mg/m3 and 0.08 micrograms/m3 for smoking workers. The PMN increased in most of the experiments but no dose response relationship could be shown. In experiments with smoking workers or when washed cotton was carded a better correlation was obtained between FEV1 decrease and endotoxin levels than for dust levels. PMID:6743581

  17. How does airway exposure of aflatoxin B1 affect serum albumin adduct concentrations? Evidence based on epidemiological study and animal experimentation.

    PubMed

    Mo, Xianwei; Lai, Hao; Yang, Yang; Xiao, Jun; He, Ke; Liu, Chao; Chen, Jiansi; Lin, Yuan

    2014-08-01

    Aflatoxin B1 (AFB1) airway inhalation represents an additional route of exposure to this toxin. However, the association between AFB1 inhalation and serum AFB1 albumin adducts remains unclear. The aim of this study was to explore the association between airway exposure to AFB1 and serum AFB1 albumin adduct concentrations via an epidemiological study, as well as in an AFB1 airway exposure animal model. Our epidemiological study was conducted in a sugar factory in the Guangxi Autonomous Region of China. In order to examine fungal contamination, air samples were obtained in the workshop and areas outside the workshop, such as the office and nearby store. Dust samples were also collected from the bagasse warehouse and presser workshop, and were analyzed using an indirect competitive enzyme-linked immunosorbent assay (ELISA). Additionally, blood samples were collected from a total of 121 workshop workers, and a control group (n = 80) was comprised of workers who undertook administrative tasks or other work outside the workshop. The animal experiment was conducted in the laboratory animal center of Guangxi Medical University, where a total of 60 adult male rabbits were involved in this study. By intubation, AFB1 was administered in three groups of rabbits daily, at dose rates of 0.075, 0.05 and 0.025 mg/kg/day for a period of 7 days. Blood samples were collected on day 1, day 3, day 7 and day 21, and the measurements of the AFB1 albumin adducts in the serum were performed by a double antibody sandwich ELISA. The epidemiological study showed that serum albumin adducts were detected in 67 workshop workers (55.37%), and the values ranged 6.4 pg/mg albumin to 212 pg/mg albumin (mean value: 51 ± 4.62 pg/mg albumin). In contrast, serum albumin adducts were detected in only 7 control group participants, with the values ranging from 9 pg AFB1/mg albumin to 59 pg/mg albumin (mean value: 20 ± 13.72 pg/mg albumin). The animal experiment revealed that the rabbits had detectable

  18. The impact of exposure to images of ideally thin models in TV commercials on eating behavior: an experimental study with women diagnosed with bulimia nervosa.

    PubMed

    Rühl, Ilka; Legenbauer, Tanja; Hiller, Wolfgang

    2011-09-01

    This study investigates whether eating behavior in women with diagnosed bulimia nervosa is influenced by prior exposure to images of ideally thin models. Twenty-six participants diagnosed with bulimia nervosa (BN) and 30 normal controls (NC) were exposed to body-related and neutral TV commercials; then food that typically triggers binge eating was provided, and the amount of food eaten was measured. No significant difference for food intake between NC and BN could be found, but food intake for BN was predicted by the degree of thoughts related to eating behaviors during exposure to the thin ideal. No impact of general body image or eating pathology on food intake could be found. The results emphasize the importance of action-relevance of dysfunctional cognitions for the maintenance of eating-disordered behaviors in women with bulimia nervosa, when exposed to eating-disorder-specific triggers.

  19. Design issues for evaluating seedling exposure studies.

    Treesearch

    E. Charles Peterson; A. Robert. Mickler

    1993-01-01

    Tree seedling studies, covering a wide range of experimental conditions in pollutant treatment, species, facilities, and exposure regimes, have become commonplace in forestry research for assessing the actual and potential environmental effects of air pollutants on forest ecosystems. While assuring a wide breadth of scientific information, sufficient consideration has...

  20. TOLUENE EXPERIMENTAL EXPOSURES IN HUMANS: PHARMACOKINETICS AND BEHAVIOR

    EPA Science Inventory

    Toluene Experimental Exposures in Humans:
    Pharmacokinetics and Behavioral Effects
    (Ongoing Research)

    Vernon A. Benignus1, Philip J. Bushnell2 and William K. Boyes2

    Human subjects will be exposed to 250 and 500 ppm toluene for one hour in the Human St...

  1. TOLUENE EXPERIMENTAL EXPOSURES IN HUMANS: PHARMACOKINETICS AND BEHAVIOR

    EPA Science Inventory

    Toluene Experimental Exposures in Humans:
    Pharmacokinetics and Behavioral Effects
    (Ongoing Research)

    Vernon A. Benignus1, Philip J. Bushnell2 and William K. Boyes2

    Human subjects will be exposed to 250 and 500 ppm toluene for one hour in the Human St...

  2. Experimental study on the survival of the water hyacinth (Eichhornia crassipes (Mart.) Solms--Pontederiaceae) under different oil doses and times of exposure.

    PubMed

    Lopes, Aline; Piedade, Maria Teresa Fernandez

    2014-12-01

    In the last decades, petroleum activities have increased in the Brazilian Amazon where there is oil exploration on the Urucu River, a tributary of the Amazon River, about 600 km from the city of Manaus. Particularly, transportation via the Amazon River to reach the oil refinery in Manaus may compromise the integrity of the large floodplains that flank hundreds of kilometers of this major river. In the Amazon floodplains, plant growth and nutrient cycling are related to the flood pulse. When oil spills occur, floating oil on the water surface is dispersed through wind and wave action in the littoral region, thus affecting the vegetation of terrestrial and aquatic environments. If pollutants enter the system, they are absorbed by plants and distributed in the food chain via plant consumption, mortality, and decomposition. The effect of oil on the growth and survival of vegetation in these environments is virtually unknown. The water hyacinth [Eichhornia crassipes (Mart.) Solms] has a pantropical distribution but is native to the Amazon, often growing in high-density populations in the floodplains where it plays an important role as shelter and food source for aquatic and terrestrial biota. The species is well known for its high capacity to absorb and tolerate high levels of heavy metal ions. To study the survival and response of water hyacinth under six different oil doses, ranging from 0 to 150 ml l(-1), and five exposure times (1, 5, 10, 15, and 20 days), young individuals distributed in a completely randomized design experiment composed of vessels with a single individual each were followed over a 50-day period (30-day acclimatization, 20 days under oil treatments). Growth parameters, biomass, visual changes in the plants, and pH were recorded at 1, 5, 10, 15, and 20 days. Increasing the time of oil exposure caused a decrease in biomass, ratio of live/dead biomass and length of leaves, and an increase in the number of dead leaves. Dose of oil and time of exposure

  3. Cadmium osteotoxicity in experimental animals: Mechanisms and relationship to human exposures

    SciTech Connect

    Bhattacharyya, Maryka H.

    2009-08-01

    Extensive epidemiological studies have recently demonstrated increased cadmium exposure correlating significantly with decreased bone mineral density and increased fracture incidence in humans at lower exposure levels than ever before evaluated. Studies in experimental animals have addressed whether very low concentrations of dietary cadmium can negatively impact the skeleton. This overview evaluates results in experimental animals regarding mechanisms of action on bone and the application of these results to humans. Results demonstrate that long-term dietary exposures in rats, at levels corresponding to environmental exposures in humans, result in increased skeletal fragility and decreased mineral density. Cadmium-induced demineralization begins soon after exposure, within 24 h of an oral dose to mice. In bone culture systems, cadmium at low concentrations acts directly on bone cells to cause both decreases in bone formation and increases in bone resorption, independent of its effects on kidney, intestine, or circulating hormone concentrations. Results from gene expression microarray and gene knock-out mouse models provide insight into mechanisms by which cadmium may affect bone. Application of the results to humans is considered with respect to cigarette smoke exposure pathways and direct vs. indirect effects of cadmium. Clearly, understanding the mechanism(s) by which cadmium causes bone loss in experimental animals will provide insight into its diverse effects in humans. Preventing bone loss is critical to maintaining an active, independent lifestyle, particularly among elderly persons. Identifying environmental factors such as cadmium that contribute to increased fractures in humans is an important undertaking and a first step to prevention.

  4. Acute effects of cigarette smoke exposure on experimental skin flaps

    SciTech Connect

    Nolan, J.; Jenkins, R.A.; Kurihara, K.; Schultz, R.C.

    1985-04-01

    Random vascular patterned caudally based McFarlane-type skin flaps were elevated in groups of Fischer 344 rats. Groups of rats were then acutely exposed on an intermittent basis to smoke generated from well-characterized research filter cigarettes. Previously developed smoke inhalation exposure protocols were employed using a Maddox-ORNL inhalation exposure system. Rats that continued smoke exposure following surgery showed a significantly greater mean percent area of flap necrosis compared with sham-exposed groups or control groups not exposed. The possible pathogenesis of this observation as well as considerations and correlations with chronic human smokers are discussed. Increased risks of flap necrosis by smoking in the perioperative period are suggested by this study.

  5. Human environmental and occupational exposures to boric acid: reconciliation with experimental reproductive toxicity data.

    PubMed

    Bolt, Hermann M; Başaran, Nurşen; Duydu, Yalçın

    2012-01-01

    The reproductive toxicity of boric acid and borates is a matter of current regulatory concern. Based on experimental studies in rats, no-observed-adverse-effect levels (NOAELs) were found to be 17.5 mg boron (B)/kg body weight (b.w.) for male fertility and 9.6 mg B/kg b.w. for developmental toxicity. Recently, occupational human field studies in highly exposed cohorts were reported from China and Turkey, with both studies showing negative results regarding male reproduction. A comparison of the conditions of these studies with the experimental NOAEL conditions are based on reported B blood levels, which is clearly superior to a scaling according to estimated B exposures. A comparison of estimated daily B exposure levels and measured B blood levels confirms the preference of biomonitoring data for a comparison of human field studies. In general, it appears that high environmental exposures to B are lower than possible high occupational exposures. The comparison reveals no contradiction between human and experimental reproductive toxicity data. It clearly appears that human B exposures, even in the highest exposed cohorts, are too low to reach the blood (and target tissue) concentrations that would be required to exert adverse effects on reproductive functions.

  6. Considerations for evaluating controlled exposure studies of tree seedlings.

    Treesearch

    E. Charles Peterson; A. Robert. Mickler

    1994-01-01

    Tree seedling exposure studies, covering a wide range of experimental conditions in pollutant treatments, species, facilities, and exposure regimes, have been conducted during the past several years to determine acute effects and relative sensitivity of tree species in response to simulated acid precipitation and gaseous pollutants. Because of tile difficulties...

  7. Sensor Exposure, Exploitation, and Experimentation Environment (SE4)

    NASA Astrophysics Data System (ADS)

    Buell, D.; Duff, F.; Goding, J.; Bankston, M.; McLaughlin, T.; Six, S.; Taylor, S.; Wootton, S.

    2011-09-01

    As the resident space object population increases from new launches and events such as the COSMOS/IRIDIUM collision, the maintenance of high-level Space Situational Awareness (SSA) has become increasingly difficult. To maintain situational awareness of the changing environment, new systems and methods must be developed. The Sensor Exposure, Exploitation and Experimentation Environment (SE4) provides a platform to illustrate “The Art of the Possible” that shows the potential benefit of enriched sensor data collections and real-time data sharing. Through modeling and simulation, and a net-centric architecture, SE4 shows the added value of sharing data in real-time and exposing new types of sensor data. The objective of SE4 is to develop an experimentation and innovation environment for sensor data exposure, composable sensor capabilities, reuse, and exploitation that accelerates the delivery of needed Command and Control, Intelligence, Surveillance, and Reconnaissance capabilities to the warfighter. Through modeling, simulation and rapid prototyping, the art of the possible for a fully-connected, net-centric space Command and Control (C2) and sensor enterprise can be demonstrated. This paper provides results that demonstrate the potential for faster cataloging of breakup events and additional event monitoring that are possible with data available today in the Space Surveillance Network (SSN). Demonstrating the art of the possible for the enterprise will guide net-centric requirements definition and facilitate discussions with stakeholder organizations on the Concept of Operations (CONOPS), policy, and Tactics, Techniques, and Procedures (TTP) evolution necessary to take full advantage of net-centric operations. SE4 aligns with direction from Secretary Gates and the Chairman Joint Chief of Staff that emphasizes the need to get the most out of our existing systems. Continuing to utilize SE4 will enable the enterprise by demonstrating the benefits of applying

  8. Experimental approaches for exposure to sized glass fibers.

    PubMed Central

    Bernstein, D M; Drew, R T; Kuschner, M

    1980-01-01

    A number of studies have shown that glass fibers induce both malignant mesothelioma and fibrosis in rats and that these reactions may be primarily a function of the physical properties of the fiber. However, these studies were carried out with fibers having broad size distributions and used methods of administration which bear little resemblance to the way man is exposed. To better characterize the health effects of glass fibers, techniques have been developed to expose rats to glass fibers of defined sizes by intratracheal instillation of aqueous suspensions and by "nose only" inhalation exposure, and to determine the deposition, translocation, and ultimate fate of these fibers in the rat. The fibers have known size distributions with geometric mean diameters of 1.5 micrometers (sigma g = 1.1) and lengths of either 5 micrometers (sigma g = 1.49) or 60 micrometers (sigma g = 3.76). The fibers have been activated with neutron irradiation. Of the several resulting radionuclides, 65Zn appeared to be the most suitable for long-term clearance studies by use of in vivo whole body radioassay techniques. A fluidized bed aerosol generator has been developed to expose rats by "nose only" inhalation to approximately 500 fibers/cm3. The generator and exposure system permits reuse of fibers which pass through the exposure chamber and produces no significant alteration of the fiber size distribution. Rats were exposed by intratracheal instillations to 20 mg of the longer fibers and to equal numbers (2 mg) and equal mass (20 mg) of the shorter fibers. Through approximately 19 weeks little difference was observed in the whole rat clearance rate of long versus short fibers in the initial exposure group. Histopathology, however, showed differences at this time with the short fibers apparently successfully phagocytized by alveolar macrophages and cleared to the lymph nodes, while the long fibers were not. Images FIGURE 3. FIGURE 6. FIGURE 7. FIGURE 8. FIGURE 9. FIGURE 10. PMID

  9. Evaporite Caprock Integrity. An experimental study of reactive mineralogy and pore-scale heterogeneity during brine-CO2 exposure

    SciTech Connect

    Smith, Megan M.; Sholokhova, Yelena; Hao, Yue; Carroll, Susan A.

    2012-07-25

    Characterization and geochemical data are presented from a core-flooding experiment on a sample from the Three Fingers evaporite unit forming the lower extent of caprock at the Weyburn-Midale reservoir, Canada. This low-permeability sample was characterized in detail using X-ray computed microtomography before and after exposure to CO 2-acidified brine, allowing mineral phase and voidspace distributions to be quantified in three dimensions. Solution chemistry indicated that CO 2-acidified brine preferentially dissolved dolomite until saturation was attained, while anhydrite remained unreactive. Dolomite dissolution contributed to increases in bulk permeability through the formation of a localized channel, guided by microfractures as well as porosity and reactive phase distributions aligned with depositional bedding. An indirect effect of carbonate mineral reactivity with CO 2-acidified solution is voidspace generation through physical transport of anhydrite freed from the rock matrix following dissolution of dolomite. The development of high permeability fast pathways in this experiment highlights the role of carbonate content and potential fracture orientations in evaporite caprock formations considered for both geologic carbon sequestration and CO 2-enhanced oil recovery operations.

  10. 40 CFR 158.250 - Experimental use permit data requirements for human exposure.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Experimental use permit data requirements for human exposure. 158.250 Section 158.250 Protection of Environment ENVIRONMENTAL PROTECTION... Experimental use permit data requirements for human exposure. No data for applicator exposure and...

  11. 40 CFR 158.250 - Experimental use permit data requirements for human exposure.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Experimental use permit data requirements for human exposure. 158.250 Section 158.250 Protection of Environment ENVIRONMENTAL PROTECTION... Experimental use permit data requirements for human exposure. No data for applicator exposure and...

  12. 40 CFR 158.250 - Experimental use permit data requirements for human exposure.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Experimental use permit data requirements for human exposure. 158.250 Section 158.250 Protection of Environment ENVIRONMENTAL PROTECTION... Experimental use permit data requirements for human exposure. No data for applicator exposure and post...

  13. 40 CFR 158.250 - Experimental use permit data requirements for human exposure.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Experimental use permit data requirements for human exposure. 158.250 Section 158.250 Protection of Environment ENVIRONMENTAL PROTECTION... Experimental use permit data requirements for human exposure. No data for applicator exposure and post...

  14. 40 CFR 158.250 - Experimental use permit data requirements for human exposure.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... requirements for human exposure. 158.250 Section 158.250 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS DATA REQUIREMENTS FOR PESTICIDES Experimental Use Permits § 158.250 Experimental use permit data requirements for human exposure. No data for applicator exposure and post...

  15. 8-isoprostane in exhaled breath condensate after experimental exposure to wood smoke in humans.

    PubMed

    Murgia, N; Barregard, L; Sallsten, G; Almstrand, A C; Montuschi, P; Ciabattoni, G; Olin, A C

    2016-01-01

    Wood smoke, a well-known indoor and outdoor air pollutant, may cause adverse health effects through oxidative stress. In this study 8-isoprostane, a biomarker of oxidative stress, was measured in exhaled breath condensate (EBC) and urine before and after experimental exposure to wood smoke. The results were compared with measurements of other biomarkers of oxidative stress and inflammation. Thirteen subjects were exposed first to clean air and then, after 1 week, to wood smoke in an exposure chamber during 4-hour sessions. Exhaled breath condensate, exhaled nitric oxide, blood and urine were sampled before and at various intervals after exposure to wood smoke and clean air. Exhaled breath condensate was examined for 8-isoprostane and malondialdehyde (MDA), while exhaled air was examined for nitric oxide, serum for Clara cell protein (CC16) and urine for 8-isoprostane. 8-isoprostane in EBC did not increase after wood smoke exposure and its net change immediately after exposure was inversely correlated with net changes in MDA (r(s)= -0.57, p= 0.041) and serum CC16 (S-CC16) (r(p)= -0.64, p= 0.020) immediately after the exposure. No correlation was found between 8-isoprostane in urine and 8-isoprostane in EBC. In this study controlled wood smoke exposure in healthy subjects did not increase 8-isoprostane in EBC.

  16. RESULTS FROM THE AHS PESTICIDE EXPOSURE STUDY

    EPA Science Inventory

    The Agricultural Health Study/Pesticide Exposure Study (AHS/PES) measured exposures resulting from agricultural use of 2,4-D and chlorpyrifos for a subset of applicators in the AHS cohort. Through on-farm measurements and observations, data collected in the exposure study will...

  17. RESULTS FROM THE AHS PESTICIDE EXPOSURE STUDY

    EPA Science Inventory

    The Agricultural Health Study/Pesticide Exposure Study (AHS/PES) measured exposures resulting from agricultural use of 2,4-D and chlorpyrifos for a subset of applicators in the AHS cohort. Through on-farm measurements and observations, data collected in the exposure study will...

  18. EXPERIMENTAL STUDIES ON INFLAMMATION

    PubMed Central

    Wolf, Elizabeth Pauline

    1921-01-01

    1. Wright's method for the study of chemotaxis of leucocytes in vitro, slightly modified, has been found to be most satisfactory in the estimation of the degree of chemotaxis of various substances, because it is possible to make an exact quantitative determination of the leucocytes that have migrated from the blood clot and adhere to the surfaces containing the tested substance. 2. The calcium ion is the only inorganic ion per se which is found to be positively chemotactic under the conditions of these experiments. It is markedly chemotactic in all concentrations and in all combinations, except the citrate. Here the negative chemotaxis of the citrate ion neutralizes the positive chemotaxis of the calcium ion, and neutrality of chemotactic effect results. 3. The sodium and magnesium ions themselves are neutral. Magnesium and sodium salts are dependent upon the negative ion with which the magnesium or sodium is combined for such positive or negative chemotaxis as is exhibited. All the phosphates of sodium, whether tri-, di-, or monobasic salts, are markedly positively chemotactic, and when combined with other reagents which are themselves neutral or negatively chemotactic, produce marked positive chemotaxis. The blood of a person who has taken phosphates either by mouth or intravenously shows a great increase in chemotaxis with sodium phosphate, with calcium chloride, and even with sodium chloride which is ordinarily neutral. 4. All potassium salts are negatively chemotactic. 5. Many substances act synergistically as regards chemotaxis; e.g., when strontium and magnesium salts are mixed there is a marked increase in chemotaxis. Sodium phosphate acts synergistically with calcium chloride. 6. Mercury salts fix the leucocytes in this method so that their influence on chemotaxis cannot be determined. 7. Morphine and morphine salts are positively chemotactic; this is contrary to the results obtained by others with different methods. 8. Substances which produce a very

  19. Y-12 Uranium Exposure Study

    SciTech Connect

    Eckerman, K.F.; Kerr, G.D.

    1999-08-05

    Following the recent restart of operations at the Y-12 Plant, the Radiological Control Organization (RCO) observed that the enriched uranium exposures appeared to involve insoluble rather than soluble uranium that presumably characterized most earlier Y-12 operations. These observations necessitated changes in the bioassay program, particularly the need for routine fecal sampling. In addition, it was not reasonable to interpret the bioassay data using metabolic parameter values established during earlier Y-12 operations. Thus, the recent urinary and fecal bioassay data were interpreted using the default guidance in Publication 54 of the International Commission on Radiological Protection (ICRP); that is, inhalation of Class Y uranium with an activity median aerodynamic diameter (AMAD) of 1 {micro}m. Faced with apparently new workplace conditions, these actions were appropriate and ensured a cautionary approach to worker protection. As additional bioassay data were accumulated, it became apparent that the data were not consistent with Publication 54. Therefore, this study was undertaken to examine the situation.

  20. Smoke-Free School Policy and Exposure to Secondhand Smoke: A Quasi-Experimental Analysis

    PubMed Central

    Kennedy, Ryan David; Baskerville, Neill Bruce

    2016-01-01

    Introduction: Tobacco control prevention efforts are important to protect people from exposure to dangerous tobacco smoke, support cessation, and reduce tobacco-use initiation. While smoke-free laws have been a widespread tobacco control strategy, little work has been done to examine the impact of smoke-free school policies. The objective of this study is to evaluate the impact of provincial smoke-free school ground policies on youth-reported exposure to secondhand smoke (SHS) on school property. Methods: This study used a nationally representative sample of 20 388 youth aged 15–18 from the 2005–2012 Canadian Tobacco Use Monitoring Survey. A quasi-experimental design was used to evaluate the impact of smoke-free school policies on SHS exposure. Results: Approximately over half (52%) of respondents reported SHS exposure on a school property in the past month. Smoke-free school policy had a statistically significant effect on SHS exposure. Specifically, the adoption of smoke-free school reduced the probability of SHS exposure by about 8 percentage points. Respondents who were smokers were more likely to report being exposed to SHS than nonsmokers. Likewise, those living in urban areas had higher probability of being exposed to SHS than those living in rural parts of Canada. Conclusions: Reported exposure to tobacco smoke did decrease after the introduction of smoke-free ground policies; however, almost half of high-school aged youth report exposure in the last month. Across Canada, provincial health authorities as well as school administers may need to assess the implementation of these smoke-free policies and improve enforcement strategies to further reduce exposure to dangerous SHS. PMID:25847291

  1. Smoke-Free School Policy and Exposure to Secondhand Smoke: A Quasi-Experimental Analysis.

    PubMed

    Azagba, Sunday; Kennedy, Ryan David; Baskerville, Neill Bruce

    2016-02-01

    Tobacco control prevention efforts are important to protect people from exposure to dangerous tobacco smoke, support cessation, and reduce tobacco-use initiation. While smoke-free laws have been a widespread tobacco control strategy, little work has been done to examine the impact of smoke-free school policies. The objective of this study is to evaluate the impact of provincial smoke-free school ground policies on youth-reported exposure to secondhand smoke (SHS) on school property. This study used a nationally representative sample of 20 388 youth aged 15-18 from the 2005-2012 Canadian Tobacco Use Monitoring Survey. A quasi-experimental design was used to evaluate the impact of smoke-free school policies on SHS exposure. Approximately over half (52%) of respondents reported SHS exposure on a school property in the past month. Smoke-free school policy had a statistically significant effect on SHS exposure. Specifically, the adoption of smoke-free school reduced the probability of SHS exposure by about 8 percentage points. Respondents who were smokers were more likely to report being exposed to SHS than nonsmokers. Likewise, those living in urban areas had higher probability of being exposed to SHS than those living in rural parts of Canada. Reported exposure to tobacco smoke did decrease after the introduction of smoke-free ground policies; however, almost half of high-school aged youth report exposure in the last month. Across Canada, provincial health authorities as well as school administers may need to assess the implementation of these smoke-free policies and improve enforcement strategies to further reduce exposure to dangerous SHS. © The Author 2015. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco.

  2. Air Pollution Exposure Modeling for Health Studies

    EPA Science Inventory

    Dr. Michael Breen is leading the development of air pollution exposure models, integrated with novel personal sensor technologies, to improve exposure and risk assessments for individuals in health studies. He is co-investigator for multiple health studies assessing the exposure ...

  3. Cadmium Osteotoxicity in Experimental Animals: Mechanisms and Relationship to Human Exposures

    PubMed Central

    Bhattacharyya, Maryka H.

    2009-01-01

    Extensive epidemiological studies have recently demonstrated increased cadmium exposure correlating significantly with decreased bone mineral density and increased fracture incidence in humans at lower exposure levels than ever before evaluated. Studies in experimental animals have addressed whether very low concentrations of dietary cadmium can negatively impact the skeleton. This overview evaluates results in experimental animals regarding mechanisms of action on bone and the application of these results to humans. Results demonstrate that long-term dietary exposures in rats, at levels corresponding to environmental exposures in humans, result in increased skeletal fragility and decreased mineral density. Cadmium-induced demineralization begins soon after exposure, within 24 hours of an oral dose to mice. In bone culture systems, cadmium at low concentrations acts directly on bone cells to cause both decreases in bone formation and increases in bone resorption, independent of its effects on kidney, intestine, or circulating hormone concentrations. Results from gene expression microarray and gene knock-out mouse models provide insight into mechanisms by which cadmium may affect bone. Application of the results to humans is considered with respect to cigarette smoke exposure pathways and direct vs. indirect effects of cadmium. Clearly, understanding the mechanism(s) by which cadmium causes bone loss in experimental animals will provide insight into its diverse effects in humans. Preventing bone loss is critical to maintaining an active, independent lifestyle, particularly among elderly persons. Identifying environmental factors such as cadmium that contribute to increased fractures in humans is an important undertaking and a first step to prevention. PMID:19463839

  4. Correlative Ultratructural Investigations of Airway Epithelium Following Experimental Exposure to Defined Air Pollutants and Lifestyle Exposure to Tobacco Smoke

    EPA Science Inventory

    Context: Investigations of cell/molecular level effects of in vivo exposure of airway mucosa of experimental animals to common irritant gases have demonstrated structural and physiological changes reflective of breaches in epithelial barrier function, presence of inflammatory cel...

  5. Correlative Ultratructural Investigations of Airway Epithelium Following Experimental Exposure to Defined Air Pollutants and Lifestyle Exposure to Tobacco Smoke

    EPA Science Inventory

    Context: Investigations of cell/molecular level effects of in vivo exposure of airway mucosa of experimental animals to common irritant gases have demonstrated structural and physiological changes reflective of breaches in epithelial barrier function, presence of inflammatory cel...

  6. Experimental studies: randomized clinical trials.

    PubMed

    Gjorgov, A N

    1998-01-01

    There are two major approaches to medical investigations: observational studies and experimental trials. The classical application of the experimental design to studies of human populations is the randomized clinical trial of the efficacy of a new drug or treatment. A further application of the experimental studies is to the testing of hypotheses about the etiology of a disease, already tested and corroborated from various forms of observational studies. Ethical considerations and requirements for consent of the experimental subjects are of primary concern in the clinical trials, and those concerns set the first and final limits for implementing a trial. General moral principles in research with human and animal beings, defined by the "Nuremberg Code," deal with strict criteria for approval, endorsement and evaluation of a clinical trial.

  7. Australian work exposures studies: occupational exposure to pesticides.

    PubMed

    Jomichen, Jasmine; El-Zaemey, Sonia; Heyworth, Jane S; Carey, Renee N; Darcey, Ellie; Reid, Alison; Glass, Deborah C; Driscoll, Tim; Peters, Susan; Abramson, Michael; Fritschi, Lin

    2017-01-01

    Pesticides are widely used in some occupational settings. Some pesticides have been classified as carcinogens; however, data on the number of workers exposed to pesticides are not available in Australia. The main aim of this study was to estimate the current prevalence of pesticide exposure in Australian workplaces. The analysis used data from the Australian Work Exposures Study, a series of nationwide telephone surveys which investigated work-related prevalence and exposure to carcinogens and asthmagens, including pesticides, among current Australian workers. Information about the respondents' current job and various demographic factors was collected in a telephone interview using the web-based tool OccIDEAS. Workers were considered exposed to pesticides if they reported applying or mixing pesticides in their current job. Of the 10 371 respondents, 410 (4%) respondents were assessed as being exposed to pesticides in the workplace, with exposure being more likely among males, individuals born in Australia, individuals with lower education level and those residing in regional or remote areas. Glyphosate was the most common active ingredient used by workers. This is the first study to describe the prevalence of occupational pesticide exposure in Australia and one of the few recent studies internationally. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  8. Long-term electromagnetic exposure of developing neuronal networks: A flexible experimental setup.

    PubMed

    Oster, Stefan; Daus, Andreas W; Erbes, Christian; Goldhammer, Michael; Bochtler, Ulrich; Thielemann, Christiane

    2016-05-01

    Neuronal networks in vitro are considered one of the most promising targets of research to assess potential electromagnetic field induced effects on neuronal functionality. A few exposure studies revealed there is currently no evidence of any adverse health effects caused by weak electromagnetic fields. Nevertheless, some published results are inconsistent. Particularly, doubts have been raised regarding possible athermal biological effects in the young brain during neuronal development. Therefore, we developed and characterized a flexible experimental setup based on a transverse electromagnetic waveguide, allowing controlled, reproducible exposure of developing neuronal networks in vitro. Measurement of S-parameters confirmed very good performance of the Stripline in the band of 800-1000 MHz. Simulations suggested a flexible positioning of cell culture dishes throughout a large exposure area, as specific absorption rate values were quite independent of their position (361.7 ± 11.4 mW/kg) at 1 W, 900 MHz. During exposure, thermal drift inside cellular medium did not exceed 0.1 K. Embryonic rat cortical neurons were cultivated on microelectrode array chips to non-invasively assess electrophysiological properties of electrogenic networks. Measurements were taken for several weeks, which attest to the experimental setup being a reliable system for long-term studies on developing neuronal tissue.

  9. Prenatal tobacco exposure: is it a risk factor for early tobacco experimentation?

    PubMed

    Cornelius, M D; Leech, S L; Goldschmidt, L; Day, N L

    2000-02-01

    Few studies have considered the etiological role of the fetal environment on the offspring's substance use. This prospective study examines the relations between the mother's prenatal and current smoking and the offspring's smoking experimentation. A low SES birth cohort of 589 10-year-olds, who have been followed since their gestation, completed a self-report questionnaire about their substance use. Half were female, and 52% were African-American. Detailed data on exposure to tobacco and other substances in the prenatal and postnatal periods were collected from the mothers. During pregnancy, 52.6% of the mothers were smokers; 59.7% were smokers when their children were 10. Six per cent of the children (37/589) reported ever smoking cigarettes, 3% had had one full alcoholic drink, and none had started to use other drugs. Maternal smoking during pregnancy was significantly associated with an increased risk of the child's tobacco experimentation. Offspring exposed to more than 1/2 pack per day during gestation had a 5.5-fold increased risk for early experimentation. Structural equation modeling showed that prenatal tobacco exposure had a direct and significant effect on the child's smoking and that maternal current smoking was not significant. Prenatal tobacco exposure also predicted child anxiety/depression and externalizing behaviors, and these outcomes affected child smoking through the mediating effect of peer tobacco use.

  10. Arsenic Exposure and Type 2 Diabetes: A Systematic Review of the Experimental and Epidemiologic Evidence

    PubMed Central

    Navas-Acien, Ana; Silbergeld, Ellen K.; Streeter, Robin A.; Clark, Jeanne M.; Burke, Thomas A.; Guallar, Eliseo

    2006-01-01

    Chronic arsenic exposure has been suggested to contribute to diabetes development. We performed a systematic review of the experimental and epidemiologic evidence on the association of arsenic and type 2 diabetes. We identified 19 in vitro studies of arsenic and glucose metabolism. Five studies reported that arsenic interfered with transcription factors involved in insulin-related gene expression: upstream factor 1 in pancreatic β-cells and peroxisome proliferative-activated receptor γ in preadipocytes. Other in vitro studies assessed the effect of arsenic on glucose uptake, typically using very high concentrations of arsenite or arsenate. These studies provide limited insight on potential mechanisms. We identified 10 in vivo studies in animals. These studies showed inconsistent effects of arsenic on glucose metabolism. Finally, we identified 19 epidemiologic studies (6 in high-arsenic areas in Taiwan and Bangladesh, 9 in occupational populations, and 4 in other populations). In studies from Taiwan and Bangladesh, the pooled relative risk estimate for diabetes comparing extreme arsenic exposure categories was 2.52 (95% confidence interval, 1.69–3.75), although methodologic problems limit the interpretation of the association. The evidence from occupational studies and from general populations other than Taiwan or Bangladesh was inconsistent. In summary, the current available evidence is inadequate to establish a causal role of arsenic in diabetes. Because arsenic exposure is widespread and diabetes prevalence is reaching epidemic proportions, experimental studies using arsenic concentrations relevant to human exposure and prospective epidemiologic studies measuring arsenic biomarkers and appropriately assessing diabetes should be a research priority. PMID:16675414

  11. Glazed clay pottery and lead exposure in Mexico: Current experimental evidence.

    PubMed

    Diaz-Ruiz, Araceli; Tristán-López, Luis Antonio; Medrano-Gómez, Karen Itzel; Torres-Domínguez, Juan Alejandro; Ríos, Camilo; Montes, Sergio

    2017-11-01

    Lead exposure remains a significant environmental problem; lead is neurotoxic, especially in developing humans. In Mexico, lead in human blood is still a concern. Historically, much of the lead exposure is attributed to the use of handcrafted clay pottery for cooking, storing and serving food. However, experimental cause-and-effect demonstration is lacking. The present study explores this issue with a prospective experimental approach. We used handcrafted clay containers to prepare and store lemonade, which was supplied as drinking water to pregnant rats throughout the gestational period. We found that clay pots, jars, and mugs leached on average 200 µg/l lead, and exposure to the lemonade resulted in 2.5 µg/dl of lead in the pregnant rats' blood. Neonates also showed increased lead content in the hippocampus and cerebellum. Caspase-3 activity was found to be statistically increased in the hippocampus in prenatally exposed neonates, suggesting increased apoptosis in that brain region. Glazed ceramics are still an important source of lead exposure in Mexico, and our results confirm that pregnancy is a vulnerable period for brain development.

  12. Experimental exposure to diesel exhaust increases arterial stiffness in man

    PubMed Central

    Lundbäck, Magnus; Mills, Nicholas L; Lucking, Andrew; Barath, Stefan; Donaldson, Ken; Newby, David E; Sandström, Thomas; Blomberg, Anders

    2009-01-01

    Introduction Exposure to air pollution is associated with increased cardiovascular morbidity, although the underlying mechanisms are unclear. Vascular dysfunction reduces arterial compliance and increases central arterial pressure and left ventricular after-load. We determined the effect of diesel exhaust exposure on arterial compliance using a validated non-invasive measure of arterial stiffness. Methods In a double-blind randomized fashion, 12 healthy volunteers were exposed to diesel exhaust (approximately 350 μg/m3) or filtered air for one hour during moderate exercise. Arterial stiffness was measured using applanation tonometry at the radial artery for pulse wave analysis (PWA), as well as at the femoral and carotid arteries for pulse wave velocity (PWV). PWA was performed 10, 20 and 30 min, and carotid-femoral PWV 40 min, post-exposure. Augmentation pressure (AP), augmentation index (AIx) and time to wave reflection (Tr) were calculated. Results Blood pressure, AP and AIx were generally low reflecting compliant arteries. In comparison to filtered air, diesel exhaust exposure induced an increase in AP of 2.5 mmHg (p = 0.02) and in AIx of 7.8% (p = 0.01), along with a 16 ms reduction in Tr (p = 0.03), 10 minutes post-exposure. Conclusion Acute exposure to diesel exhaust is associated with an immediate and transient increase in arterial stiffness. This may, in part, explain the increased risk for cardiovascular disease associated with air pollution exposure. If our findings are confirmed in larger cohorts of susceptible populations, this simple non-invasive method of assessing arterial stiffness may become a useful technique in measuring the impact of real world exposures to combustion derived-air pollution. PMID:19284640

  13. Experimental exposure to diesel exhaust increases arterial stiffness in man.

    PubMed

    Lundbäck, Magnus; Mills, Nicholas L; Lucking, Andrew; Barath, Stefan; Donaldson, Ken; Newby, David E; Sandström, Thomas; Blomberg, Anders

    2009-03-13

    Exposure to air pollution is associated with increased cardiovascular morbidity, although the underlying mechanisms are unclear. Vascular dysfunction reduces arterial compliance and increases central arterial pressure and left ventricular after-load. We determined the effect of diesel exhaust exposure on arterial compliance using a validated non-invasive measure of arterial stiffness. In a double-blind randomized fashion, 12 healthy volunteers were exposed to diesel exhaust (approximately 350 mug/m3) or filtered air for one hour during moderate exercise. Arterial stiffness was measured using applanation tonometry at the radial artery for pulse wave analysis (PWA), as well as at the femoral and carotid arteries for pulse wave velocity (PWV). PWA was performed 10, 20 and 30 min, and carotid-femoral PWV 40 min, post-exposure. Augmentation pressure (AP), augmentation index (AIx) and time to wave reflection (Tr) were calculated. Blood pressure, AP and AIx were generally low reflecting compliant arteries. In comparison to filtered air, diesel exhaust exposure induced an increase in AP of 2.5 mmHg (p = 0.02) and in AIx of 7.8% (p = 0.01), along with a 16 ms reduction in Tr (p = 0.03), 10 minutes post-exposure. Acute exposure to diesel exhaust is associated with an immediate and transient increase in arterial stiffness. This may, in part, explain the increased risk for cardiovascular disease associated with air pollution exposure. If our findings are confirmed in larger cohorts of susceptible populations, this simple non-invasive method of assessing arterial stiffness may become a useful technique in measuring the impact of real world exposures to combustion derived-air pollution.

  14. Malathion immunotoxicity in the American lobster (Homarus americanus) upon experimental exposure.

    PubMed

    De Guise, Sylvain; Maratea, Jennifer; Perkins, Christopher

    2004-03-10

    A lobster die-off reduced the 1999 fall landings in western Long Island Sound by up to more then 99%. The die-off corresponded in time with the application of pesticides for the control of mosquitoes that carried West Nile virus, a new emerging disease in North America at the time. In order to determine the possible implication of pesticide application as a direct cause or contributing factor in the die-off, we studied the effects of experimental exposure to malathion on the health of lobsters. Lobsters were exposed in 20 gallon tanks, and the direct toxicity as well as sub-lethal effects on the immune system were determined. The 96 h LC50 for malathion upon single exposure was 38 microg/l. Malathion degraded rapidly in sea water, with 65-77% lost after 1 day and 83-96% lost after 3 days. Phagocytosis was significantly decreased 3 days after a single exposure to initial water concentrations as low as 5 ppb, when measured water concentrations were as low as 0.55 ppb. Similarly, effects on phagocytosis were observed at 1, 2 and 3 weeks after the initiation of weekly exposures. Cell counts did not differ significantly upon exposure to malathion. Malathion was not detected in muscle and hepatopancreas of exposed lobsters. Evaluation of phagocytosis is a sensitive indicator of subtle sub-lethal effects of malathion, and relatively small concentrations of malathion (6-7 times lower than the LC50) can affect lobster defense mechanisms.

  15. Considerations for evaluating controlled exposure studies of tree seedlings

    SciTech Connect

    Peterson, C.E. Jr.; Mickler, R.A.

    1994-03-01

    Tree seedling exposure studies, covering a wide range of experimental conditions in pollutant treatments, species, facilities, and exposure regimes, have been conducted during the past several years to determine acute effects and relative sensitivity of tree species in response to simulated acid precipitation and gaseous pollutants. Because of the difficulties inherent in conducting controlled exposures with mature trees (e.g., size, variability among experimental units, and costs associated with replication of treatments), seedling exposure studies have been initiated as the quickest way to address these issues. However, sufficient consideration has not been given to either the comparability of seedling studies or to their appropriate inference. The statistical power of any given analysis is rarely discussed when the outcomes are published. Appropriate and documented statistics of experimenter bias are often not reported, and variability in the exposure regime (ie., treatment target levels) and the measurement of experimental variables is assumed to be zero, rather than quantified. FInally, the populations of seedlings for which seedling experiments have inferences the extent to which seedling responses are applicable to mature trees and forest condition, and the limitations in national or regional generalizations are crucial issues often left to an individual reader`s interpretation without the benefit of adequate quantitative information presented by the authors. 31 refs., 8 figs., 1 tab.

  16. TIME-INTEGRATED EXPOSURE MEASURES TO IMPROVE THE PREDICTIVE POWER OF EXPOSURE CLASSIFICATION FOR EPIDEMIOLOGIC STUDIES

    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...

  17. TIME-INTEGRATED EXPOSURE MEASURES TO IMPROVE THE PREDICTIVE POWER OF EXPOSURE CLASSIFICATION FOR EPIDEMIOLOGIC STUDIES

    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...

  18. APPROACHES FOR MEASURING APPLICATOR EXPOSURE IN THE AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY

    EPA Science Inventory

    The Agricultural Health Study (AHS) is a prospective epidemiologic study of a large cohort of pesticide applicators and their spouses in Iowa and North Carolina. The Pesticide Exposure Study is a sub-study to evaluate exposure factors and to provide data to assess exposure cla...

  19. Neurobiological effects of microwave exposure: a review focused on morphological findings in experimental animals.

    PubMed

    Orendácová, J; Orendác, M; Raceková, E; Marsala, J

    2007-01-01

    The possible risk of electromagnetic radiation (EMR) for nervous system is regularly published from the middle of 20th century. Numbers of neurobiological studies demonstrate that various EMR frequencies induce changes in nervous tissue of experimental animals but the evidence for health effect of EMR to the nervous system remains uncertain. To solve the fundamental questions about possible health hazard of modern technologies, the main producers of EMR, further intensive experimental studies on animals are needed. This review, focused on morphological findings achieved in various experimental animals, demonstrates that blood-brain barrier is the most studied morpho-functional unit of CNS in experiments with EMR. The morphological findings in experimental animals, in many cases controversial, put some evidence on nervous tissue structural damage after the EMR exposure. In spite of numerous literary data a wide range of contemporary neuro-morphological methods waits to be utilized in the EMR experimental paradigm. Using these methods could play an important role in answering the question about possible adverse effects of microwaves on nervous system.

  20. DETROIT EXPOSURE AND AEROSOL RESEARCH STUDY

    EPA Science Inventory

    The DEARS is a three-year field monitoring study that will be conducted in Detroit, Michigan and is designed to measure exposure and describe exposure relationships for air toxics, PM components, PM from specific sources, and criteria pollutants. Detroit, Michigan was considered ...

  1. DETROIT EXPOSURE AND AEROSOL RESEARCH STUDY

    EPA Science Inventory

    The DEARS is a three-year field monitoring study that will be conducted in Detroit, Michigan and is designed to measure exposure and describe exposure relationships for air toxics, PM components, PM from specific sources, and criteria pollutants. Detroit, Michigan was considered ...

  2. Experimental animal studies of radon and cigarette smoke

    SciTech Connect

    Cross, F.T.; Dagle, G.E.; Gies, R.A.; Smith, L.G.; Buschbom, R.L.

    1992-12-31

    Cigarette-smoking is a dominant cause of lung cancer and confounds risk assessment of exposure to radon decay products. Evidence in humans on the interaction between cigarette-smoking and exposure to radon decay products, although limited, indicates a possible synergy. Experimental animal data, in addition to showing synergy, also show a decrease or no change in risk with added cigarette-smoke exposures. This article reviews previous animal data developed at Compagnie Generale des Matieres Nucleaires and Pacific Northwest Laboratory (PNL) on mixed exposures to radon and cigarette smoke, and highlights new initiation-promotion-initiation (IPI) studies at PNL that were designed within the framework of a two-mutation carcinogenesis model. Also presented are the PNL exposure system, experimental protocols, dosimetry, and biological data observed to date in IPI animals.

  3. BIOMONITORING OF EXPOSURE IN FARMWORKER STUDIES

    EPA Science Inventory

    Though biomonitoring has been used in many occupational and environmental health and exposure studies, we are only beginning to understand the complexities and uncertainties involved with the biomonitoring process -- from study design, to sample collection, to chemical analysis -...

  4. BIOMONITORING OF EXPOSURE IN FARMWORKER STUDIES

    EPA Science Inventory

    Though biomonitoring has been used in many occupational and environmental health and exposure studies, we are only beginning to understand the complexities and uncertainties involved with the biomonitoring process -- from study design, to sample collection, to chemical analysis -...

  5. AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY DESIGN

    EPA Science Inventory

    The Agricultural Health Study (AHS) is a prospective epidemiologic study of a large cohort of pesticide applicators and their spouses in Iowa and North Carolina. The Pesticide Exposure Study is a sub-study to evaluate exposure factors and to provide data to assess exposure cla...

  6. AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY DESIGN

    EPA Science Inventory

    The Agricultural Health Study (AHS) is a prospective epidemiologic study of a large cohort of pesticide applicators and their spouses in Iowa and North Carolina. The Pesticide Exposure Study is a sub-study to evaluate exposure factors and to provide data to assess exposure cla...

  7. Effects of Copper Exposure on Photosynthesis and Growth of the Seagrass Cymodocea nodosa: An Experimental Assessment.

    PubMed

    Llagostera, Izaskun; Cervantes, Daniel; Sanmartí, Neus; Romero, Javier; Pérez, Marta

    2016-09-01

    Seagrasses form some of the most important coastal habitats. They may be negatively affected by trace metal contamination in certain coastal areas. In this study we experimentally assessed selected morphological and physiological traits of the seagrass Cymodocea nodosa, with increasing concentrations of copper (Cu) under controlled laboratory conditions. Short term (21 days) sub-lethal effects such as decreased maximum quantum yield, increased leaf necrosis and decreased shoot growth and shoot recruitment were clearly observed at the highest Cu exposure (5 mg L(-1)), while the effects were weaker at the intermediate concentration (2.5 mg L(-1)) and almost absent at the lowest concentration (1 mg L(-1)), indicating that this species is highly tolerant to copper exposure, at least in the short term. This fact could help to explain its distribution in relatively polluted coastal waters.

  8. Effect of chronic carbon monoxide exposure on experimental alcoholic liver injury in rats

    SciTech Connect

    Nanji, A.A. ); Jui, L.T.; French, S.W. )

    1989-01-01

    Two groups of experimental animals with pair-fed controls were studied to evaluate the effect of chronic carbon monoxide (CO) exposure on progression of experimental alcoholic liver injury. Eight pairs of male Wistar rats were continuously infused liquid diet and ethanol or isocaloric dextrose for four months. Four pairs were also exposed to CO. Liver damage was followed monthly by serum ALT and morphologic assessment of liver biopsy. Serum levels of ALT were significantly higher in the CO-ethanol group compared to other groups. Electron microscopy revealed a greater degree of cell necrosis in the CO exposed group which explained the significantly higher ALT activity in these animals. Both experimental groups had significantly greater liver damage than controls. Carboxyhemoglobin levels were not different in the ethanol-fed and control group. Our results show that chronic CO exposure enhances liver cell necrosis in ethanol-fed rats thereby lending support to the hypothesis that ethanol and hypoxia enhance cellular disruption in the liver which could be important in the pathogenesis of alcoholic liver disease in rats.

  9. Experimental Studies on Rutile Solubility

    NASA Astrophysics Data System (ADS)

    Rapp, J. F.; Klemme, S.; Butler, I. B.; Harley, S. L.

    2007-12-01

    Rutile (TiO2) is an important high field strength element (HFSE) sequestering mineral, and has been implicated in the observed depletion of HFSE in arc magmas. It is thought that rutile is insoluble in slab-derived fluids, and remains residual in the subducted slab. Indeed, experimental data indicates a very low solubility of rutile in pure H2O (Tropper and Manning, 2005), and this low solubility may result in HFSE depleted fluids imparting a depleted signature to arc magmas. However, there is scant experimental data available on rutile solubility in fluids of more complex compositions (Ayers and Watson, 1993). We are carrying out a systematic experimental study into the effect of specific chemical components on rutile solubility in fluids and also silicate melts. This should further our understanding of HFSE mobility in metamorphic rocks within subduction zones. References: J. C. Ayers and E. B. Watson (1993) Rutile solubility in supercritical aqueous fluids and the high P-T mobility of elements it concentrates. Contrib. Mineral. Petrol. 114, 321-330. P. Tropper and C. E. Manning (2005) Very low solubility of rutile in H2O at high pressure and temperature, and its implications for Ti mobility in subduction zones. American Mineralogist 90(2-3), 502-505.

  10. [Histopathologic studies in experimental uveitis].

    PubMed

    Misiuk-Hojło, Marta; Woźniak, Zdzisław; Szymaniec, Stanisław; Lugowski, Czesław; Agopsowicz, Karolina

    2004-01-01

    Experimental uveitis is one of the main models in the diseases of autoimmunological background. The purpose of this paper was to analyze the quantitative histological changes in the experimental uveitis, induced by different types of homogenous endotoxin salts of Havnia alvei. We studied 74 eyes of Lewis rats (males) divided into 4 groups. Each group received a homogenous salt of Havnia alvei in a single subcutaneous injection. In the 1 group-LPS Ca++, in 2 group-LPS Na++, in 3 group-LPS 981, in 4 group physiological salt (control group). The histologic and immunocitochemical examinations were performed after 24, 48 hours, and after 4 and 7 days following the injection. The histologic changes were analyzed (he intensity of inflammatory reaction) using a Highly Optimazed Microscope Enviroment system. The most intensive inflammation was observed in experimental group after 24 hours (n the LPS 981D group in 5 rats out of 6, in LPS Ca++ group in 3 rats out of 6). After 48 hours the intensity of inflammatory reaction visibly decreased. On the fourth day the inflammation revealed a minimal intensity and after 7 days was practically absent. In the control group minimal inflammation was observed only in a few rats. Cilliary body hypermia was present for 48 hours in most of the experimental rats. Only a few of them had hyperemia on the fourth day. In the posterior segment minimal inflammation was noted at the end of the first day (I and II-nd group after 24 hours); this process continued until the fourth day, on the 7th day disappeared. The most intensive inflammation of the anterior and posterior choroidal segment is caused by homogenous salts of Havnia alvei 981.

  11. Formaldehyde exposure and acute health effects study

    SciTech Connect

    Quackenboss, J.J.; Lebowitz, M.D.; Michaud, J.P.; Bronnimann, D. )

    1989-01-01

    To assess the effects of formaldehyde exposures on health, exposure groups were defined using baseline exposure and health questionnaires. Formaldehyde concentrations were poorly correlated with these exposure classifications, perhaps due to the time delay between classification and monitoring. The 151 households reported here had a mean HCHO concentration of 35 (S.E. 1.5 and median 30) {mu}g/m{sup 3}. Passive samplers prepared in our lab were calibrated in a chamber to derive an estimated sampling rate of 0.311 {mu}g/(mg {center dot} m{sup {minus}3} {center dot} hr). They were also compared to commercially available samplers inside of the homes, with a correlation coefficient of 0.896 and mean difference of 2.6 {mu}g/m{sup 3}. In this report of initial findings from an ongoing study, daily symptoms and peak expiratory flow measurements were compared with an HCHO exposure classification based on the median measured concentrations. None of the symptoms groups were related to HCHO exposure when controlling for age and sex. There was a significant relationship between HCHO exposure and variability in peak expiratory flows that was dependent on age group. It may be especially important to assess the variability in reactive individuals and children to determine the short-term effects of HCHO exposures and possible long-term consequences.

  12. Community Engagement in Observational Human Exposure Studies

    EPA Science Inventory

    Although observational human exposure studies do not deliberately expose participants to chemicals or environmental conditions, merely involving people as research participants and conducting research inside homes raises ethical issues. Community engagement offers a promising st...

  13. Community Engagement in Observational Human Exposure Studies

    EPA Science Inventory

    Although observational human exposure studies do not deliberately expose participants to chemicals or environmental conditions, merely involving people as research participants and conducting research inside homes raises ethical issues. Community engagement offers a promising st...

  14. Experimental study of vortex diffusers

    SciTech Connect

    Shakerin, S.; Miller, P.L.

    1995-11-01

    This report documents experimental research performed on vortex diffusers used in ventilation and air-conditioning systems. The main objectives of the research were (1) to study the flow characteristics of isothermal jets issuing from vortex diffusers, (2) to compare the vortex diffuser`s performance with that of a conventional diffuser, and (3) to prepare a report that disseminates the results to the designers of ventilation and air-conditioning systems. The researchers considered three diffusers: a conventional round ceiling diffuser and two different styles of vortex diffusers. Overall, the vortex diffusers create slightly more induction of ambient air in comparison to the conventional diffuser.

  15. Experimental studies of glass refining

    NASA Technical Reports Server (NTRS)

    Subramanian, R. S.; Cole, R.; Kondos, P.

    1984-01-01

    The basic components of the experimental apparatus were selected and acquired. Techniques were developed for the fabrication of the special crucibles necessary for the experiments. Arrangements were made for the analysis of glass and gas bubble samples for composition information. Donations of major equipment were received for this project from Owens, Illinois where a similar study had been conducted a few year ago. Decisions were made regarding the actual glass composition to be used, the gas to be used in the first experiments, and the temperatures at which the experiments should be conducted. A microcomputer was acquired, and work was begun on interfacing the video analyzer to it.

  16. The Effect of Exposure to Pro-Tobacco Advertising on Experimentation with Emerging Tobacco Products among U.S. Adolescents

    ERIC Educational Resources Information Center

    Agaku, Israel T.; Ayo-Yusuf, Olalekan A.

    2014-01-01

    Introduction: This study assessed the influence of exposure to pro-tobacco advertisements on experimentation with emerging tobacco products among U.S. adolescents aged =9 years, in Grades 6 to 12. Method: Data were obtained from the 2011 National Youth Tobacco Survey. Multivariate logistic regression was used to measure the association between…

  17. The Effect of Exposure to Pro-Tobacco Advertising on Experimentation with Emerging Tobacco Products among U.S. Adolescents

    ERIC Educational Resources Information Center

    Agaku, Israel T.; Ayo-Yusuf, Olalekan A.

    2014-01-01

    Introduction: This study assessed the influence of exposure to pro-tobacco advertisements on experimentation with emerging tobacco products among U.S. adolescents aged =9 years, in Grades 6 to 12. Method: Data were obtained from the 2011 National Youth Tobacco Survey. Multivariate logistic regression was used to measure the association between…

  18. [Experimental study of vestibular neurectomy].

    PubMed

    Pech, A; Cannoni, M; Appaix, M; Cahier, S; Lacour, M; Roll, J P

    1976-06-01

    The authors describe an experimental study carried out on baboons. After unilateral vestibular neurectomy, the behaviour disorders on the one hand, and on the other, modifications and temporal development of reflex muotatic excitability of the spine using Hoffmann's reflex method are analyzed. As far as behaviour is concerned, a four-day period of motor restriction following the operation causes more marked residual disorders in comparison with controls. From the neurophysiological point of view, neurectomy results in seriously disordered spinal reflexes characterized by ipsilateral hypo-excitability developing in there stages: a tw-day initial critical phase during which the disorders are at their worst, a four-day recuperative stage with partial regression of the disorders, finally a chronic compensation stage in which spinal excitability returns to normal after several months.

  19. No delayed behavioral and phenotypic responses to experimental early-life lead exposure in great tits (Parus major).

    PubMed

    Ruuskanen, Suvi; Eeva, Tapio; Kotitalo, Päivi; Stauffer, Janina; Rainio, Miia

    2015-02-01

    Early-life exposure to pollutants, such as lead, may have long-lasting consequences on health, behavior, and cognition. However, experiments on delayed effects of specific pollutants are very rare in wild animals. We experimentally exposed wild nestling great tits (Parus major) to dietary lead (high, low, or control group) in levels relevant to exposure levels of wild populations in Europe and studied delayed effects on phenotypic and behavioral traits in captivity. We also included a group of birds from a vicinity of a copper smelter, exposed to a mixture of toxic metals and altered food supply during development. This experimental setup allowed us to compare the strength of direct (exposure to lead per se) and indirect (pollution-related changes in diet) effects of pollutants. Our experimental lead treatment significantly increased lead levels in bone and feces compared with controls. However, we found no carry-over effect of early-life dietary lead on morphology, plumage coloration, or heat shock proteins. Treatment did not affect activity, exploration, neophobia, or success in learning and spatial memory task. We conclude that with the exposure levels and relatively short exposure period used, delayed effects on the measured traits were not found. However, it is important to further study other types of behavioral traits and ultimately fitness effects.

  20. A numerical and experimental investigation of crystalline silica exposure control during tuck pointing.

    PubMed

    Heitbrink, William; Bennett, James

    2006-07-01

    National Institute for Occupational Safety and Health researchers investigated control measures for the removal of mortar between bricks, using a grinder. This task, "tuck pointing," is associated with crystalline silica exposures many times greater than the permissible exposure limit enforced by the Occupational Safety and Health Administration. Previous studies showed that local exhaust ventilation (LEV) of the grinding wheel through a shroud was often ineffective. Tuck pointing occurs on a scaffold. For practical purposes, this limits the size and power of the LEV system. Thus, the goal of this study was to develop a recommended flow rate for exposure control. Flow induced by the rotating grinding wheel, flow induced by the mortar particle stream, and particle momentum are potential control challenges. Computational fluid dynamic (CFD) simulation of the grinder, supported by some experimental measurements, showed the relative importance of these factors through varying parameters and tracking particles. In a simulation of the shroud and grinding wheel, with the wheel inserted to a cutting depth of 0.750 inch flush into the brick wall, -0.461 cubic feet per meter (0.461 into the exhaust takeoff) was induced by the rotating wheel. The more realistic situation of the wheel in a cut in the wall 1.25 inches deep (forming a trench circumferentially 0.500 inch below the wheel edge) induced an airflow of 8.24 cfm out of the shroud exhaust. Experimental measurements taken for validation were 7.3% lower than the CFD value. The trench effect disappeared when a stream of 10-mu m particles was launched from the grinding wheel edge, as the simulations with and without the trench had nearly identical induced flow rates, 10.8 cfm and 10.9 cfm. We thus interpreted the particle stream as more important than the wheel in inducing flow. This insight was possible because of the power of CFD, compared to intuition and classical boundary layer analysis. In this situation of no forced

  1. Experimental effects of exposure to pornography: the moderating effect of personality and mediating effect of sexual arousal.

    PubMed

    Hald, Gert Martin; Malamuth, Neil N

    2015-01-01

    Using a randomly selected community sample of 200 Danish young adult men and women in a randomized experimental design, the study investigated the effects of a personality trait (agreeableness), past pornography consumption, and experimental exposure to non-violent pornography on attitudes supporting violence against women (ASV). We found that lower levels of agreeableness and higher levels of past pornography consumption significantly predicted ASV. In addition, experimental exposure to pornography increased ASV but only among men low in agreeableness. This relationship was found to be significantly mediated by sexual arousal with sexual arousal referring to the subjective assessment of feeling sexually excited, ready for sexual activities, and/or bodily sensations associated with being sexually aroused. In underscoring the importance of individual differences, the results supported the hierarchical confluence model of sexual aggression and the media literature on affective engagement and priming effects.

  2. Experimental Infrasound Studies in Nevada

    NASA Astrophysics Data System (ADS)

    Herrin, E. T.; Negraru, P. T.; Golden, P.; Williams, A.

    2009-12-01

    An experimental propagation study was carried out in Nevada in June 2009 on Julian days 173-177. During this field experiment we deployed 16 single channel digital infrasound recorders to monitor the munitions disposal activities near Hawthorne, NV. The sensors were deployed in a single line and placed approximately 12 km apart at distances ranging from 2 to 177 km. A four element semi-permanent infrasound array named FNIAR was installed approximately 154 km north of the detonation site in line with the individual temporary recorders. Tropospheric arrivals were observed during all days of the experiment, but during day 176 the observed arrivals had very large amplitudes. A large signal was observed at 58 km from the detonation site with amplitude as large as 4 Pascals, while at 94 km no signal was observed. At FNIAR the amplitude of the tropospheric arrival was 1 Pascal. During this day meteorological data acquired in the propagation path showed a strong jet stream to the north. On day 177 we were not able to identify tropospheric arrivals beyond 34 km, but at stations beyond 152 km we observed stratospheric arrivals. Continuous monitoring of these signals at FNIAR shows that stratospheric arrivals are the most numerous. In a two month period, from 06/15/2009 to 08/15/2009 there were 35 operational days at the Hawthorne disposal facility resulting in 212 explosions with known origin times. Based on the celerity values there were 115 explosions that have only stratospheric arrivals (celerities of 300-275 m/s), 72 explosions with both tropospheric (celerities above 330 m/s) and stratospheric arrivals, 20 explosions that were not detected and five explosions that have only tropospheric arrivals.

  3. Protobacco Media Exposure and Youth Susceptibility to Smoking Cigarettes, Cigarette Experimentation, and Current Tobacco Use among US Youth.

    PubMed

    Fulmer, Erika B; Neilands, Torsten B; Dube, Shanta R; Kuiper, Nicole M; Arrazola, Rene A; Glantz, Stanton A

    2015-01-01

    Youth are exposed to many types of protobacco influences, including smoking in movies, which has been shown to cause initiation. This study investigates associations between different channels of protobacco media and susceptibility to smoking cigarettes, cigarette experimentation, and current tobacco use among US middle and high school students. By using data from the 2012 National Youth Tobacco Survey, structural equation modeling was performed in 2013. The analyses examined exposure to tobacco use in different channels of protobacco media on smoking susceptibility, experimentation, and current tobacco use, accounting for perceived peer tobacco use. In 2012, 27.9% of respondents were never-smokers who reported being susceptible to trying cigarette smoking. Cigarette experimentation increased from 6.3% in 6th grade to 37.1% in 12th grade. Likewise, current tobacco use increased from 5.2% in 6th grade to 33.2% in 12th grade. Structural equation modeling supported a model in which current tobacco use is associated with exposure to static advertising through perception of peer use, and by exposure to tobacco use depicted on TV and in movies, both directly and through perception of peer use. Exposure to static advertising appears to directly increase smoking susceptibility but indirectly (through increased perceptions of peer use) to increase cigarette experimentation. Models that explicitly incorporate peer use as a mediator can better discern the direct and indirect effects of exposure to static advertising on youth tobacco use initiation. These findings underscore the importance of reducing youth exposure to smoking in TV, movies, and static advertising.

  4. Protobacco Media Exposure and Youth Susceptibility to Smoking Cigarettes, Cigarette Experimentation, and Current Tobacco Use among US Youth

    PubMed Central

    Fulmer, Erika B.; Neilands, Torsten B.; Dube, Shanta R.; Kuiper, Nicole M.; Arrazola, Rene A.; Glantz, Stanton A.

    2015-01-01

    Purpose Youth are exposed to many types of protobacco influences, including smoking in movies, which has been shown to cause initiation. This study investigates associations between different channels of protobacco media and susceptibility to smoking cigarettes, cigarette experimentation, and current tobacco use among US middle and high school students. Methods By using data from the 2012 National Youth Tobacco Survey, structural equation modeling was performed in 2013. The analyses examined exposure to tobacco use in different channels of protobacco media on smoking susceptibility, experimentation, and current tobacco use, accounting for perceived peer tobacco use. Results In 2012, 27.9% of respondents were never-smokers who reported being susceptible to trying cigarette smoking. Cigarette experimentation increased from 6.3% in 6th grade to 37.1% in 12th grade. Likewise, current tobacco use increased from 5.2% in 6th grade to 33.2% in 12th grade. Structural equation modeling supported a model in which current tobacco use is associated with exposure to static advertising through perception of peer use, and by exposure to tobacco use depicted on TV and in movies, both directly and through perception of peer use. Exposure to static advertising appears to directly increase smoking susceptibility but indirectly (through increased perceptions of peer use) to increase cigarette experimentation. Models that explicitly incorporate peer use as a mediator can better discern the direct and indirect effects of exposure to static advertising on youth tobacco use initiation. Conclusions These findings underscore the importance of reducing youth exposure to smoking in TV, movies, and static advertising. PMID:26308217

  5. Transcriptomic response of Argopecten purpuratus post-larvae to copper exposure under experimental conditions.

    PubMed

    Zapata, Manuel; Tanguy, Arnaud; David, Elise; Moraga, Dario; Riquelme, Carlos

    2009-08-01

    Few studies have described the molecular response of mollusk larvae to heavy metal exposure. We investigated the response of Chilean scallop Argopecten purpuratus post-larvae to copper exposure under experimental conditions. Post-larvae were maintained with and without copper stress in tanks containing netlon collectors with biofilms that were formed by the bacterium Halomonas sp. and the diatom Amphora sp., known to increase larval settlement. We focused on the analysis of the differential expression patterns of genes associated with copper response. A suppression subtractive hybridization method was used to identify copper-specific up- and down-regulated genes in the post-larvae following 4 days and 8 days exposure to 2.5 and 10 microg/l Cu(+2). This method revealed 145 different sequences corresponding to 10 major physiological functions. The expression of 15 potentially regulated genes was analyzed by real-time PCR in post-larvae at different sampling times during the copper stress. The genes chosen were alpha tubulin, elongation factor 1-alpha (EF1A), tributylin binding protein type 1 (TBT), NADH dehydrogenase subunit 2 (NADH2), cavortin, glutathione peroxidase (GPx), ferritin, heat shock protein 70 (HSP70), Pam highwire rpm1 (Phr1), insulin-like growth factor 1 (IGF1), cellulase, and ribosomal proteins: L18, L44, S3a and S15. This study contributes to the characterization of potential genetic markers that could be used in future environmental monitoring and to explore new mechanisms of stress tolerance in marine mollusk species, especially in early stages of development.

  6. LC–MS-MS Analysis of Urinary Biomarkers of Imazalil Following Experimental Exposures

    PubMed Central

    Faniband, Moosa H.; Littorin, Margareta; Ekman, Eva; Jönsson, Bo A.G.; Lindh, Christian H.

    2015-01-01

    Imazalil (IMZ) is a fungicide used in the cultivation of vegetables, such as cucumbers, in green houses or post-harvest on fruit to avoid spoilage due to fungal growth. Agricultural workers can be occupationally exposed to IMZ and the general public indirectly by the diet. The purpose of this study was to develop and validate an LC–MS-MS method for the analysis of IMZ in human urine. The method used electrospray ionization and selected reaction monitoring in the positive mode. Excellent linearity was observed in the range 0.5–100 ng/mL. The limit of detection of the method was 0.2 ng/mL, and the limit of quantitation 0.8 ng/mL. The method showed good within-run, between-run and between-batch precision, with a coefficient of variation <15%. The method was applied to analyze urine samples obtained from two human volunteers following experimental oral and dermal exposure. The excretion of IMZ seemed to follow a two-compartment model and first-order kinetics. In the oral exposure, the elimination half-life of IMZ in the rapid excretion phase was 2.6 and 1.9 h for the female and the male volunteer, respectively. In the slower excretion phase, it was 7.6 and 13 h, respectively. In the dermal exposure, the excretion seemed to follow a single-compartment model and first-order kinetics. The elimination half-life was 10 and 6.6 h for the female and the male volunteer, respectively. Although the study is limited to two volunteers, some information on basic toxicokinetics and metabolism of IMZ in humans is presented. PMID:26324206

  7. Estimating exposure using kriging: a simulation study.

    PubMed Central

    Wartenberg, D; Uchrin, C; Coogan, P

    1991-01-01

    Retrospective studies of disease often are limited by the resolution of the exposure measurements. For example, in a typical study of adverse health effects from contaminated groundwater, the number of wells sampled may range from only a few to as many as several dozen, while the number of cases and controls may be in the hundreds or more. To derive individual estimates of exposure for wells that were not sampled, investigators must extrapolate. In this study, we compare three methods of extrapolating from a limited number of observations to estimate individual exposures. Using two naive models of groundwater contamination, we compare nearest neighbor interpolation, inverse distance squared weighting, and kriging for estimating exposure based on a limited number of measurements. Our results show that although kriging is a statistically optimal method, it is not markedly better than simpler interpolation algorithms, though it is considerably more complex to use. Aberrant well measurements and discontinuities are problematic for all methods. We provide some guidance in interpolating data and outline a more comprehensive comparison of methodology. PMID:1954944

  8. Retinal hemorrhages associated with in utero exposure to cocaine. Experimental and clinical findings.

    PubMed

    Silva-Araújo, A; Tavares, M A; Patacao, M H; Carolino, R M

    1996-01-01

    The use of drugs of abuse--e.g., cocaine--during pregnancy has been associated with abnormalities of the visual system. The authors studied the effects of prenatal exposure to drugs of abuse, especially cocaine, on the vascular system of the retina in newborn infants and in an experimental model in the rat. The animal study was conducted in pregnant Wistar rats injected subcutaneously with cocaine hydrochloride (60 mg/kg body weight/day) from gestation days 8 to 22. Male offspring were killed at postnatal days 7, 14, and 30 and perfused with fixative, and the retinas were dissected and processed for microscopic observation. The ophthalmologic observations were conducted in a population of newborn infants born to women who abused many drugs during pregnancy and in a control group of women with no history of illicit drug use. Vascular disruptive lesions were seen after prenatal exposure to cocaine in the rat: round intraretinal hemorrhages, ischemic and hypoperfused areas located at the temporal part and often extending from the posterior pole to the periphery of the retina. The ophthalmologic observation of the newborns showed a higher incidence of vascular disruptive lesions in infants in whom exposure to drugs of abuse was affirmative during pregnancy. In the cases in which cocaine consumption was reported, they consisted in blot full-thickness hemorrhages with rounded domed contours suggestive of venous occlusion and retinal ischemia, very similar to the lesions seen in the animal model. These hemorrhagic lesions, morphologically similar to neonatal retinal hemorrhages, had a higher incidence than in controls; they also took longer to resolve when compared with the reabsorption time of the neonatal hemorrhages due to birth trauma and the hemorrhagic lesions in newborns of mothers in whom consumption of other drugs--but not cocaine--were reported. A topographic and morphologic parallelism can be established between the retinal vascular alterations found in humans

  9. Industrial Noise and Tooth Wear - Experimental Study

    PubMed Central

    Cavacas, Maria Alzira; Tavares, Vitor; Borrecho, Gonçalo; Oliveira, Maria João; Oliveira, Pedro; Brito, José; Águas, Artur; dos Santos, José Martins

    2015-01-01

    Tooth wear is a complex multifactorial process that involves the loss of hard dental tissue. Parafunctional habits have been mentioned as a self-destructive process caused by stress, which results in hyperactivity of masticatory muscles. Stress manifests itself through teeth grinding, leading to progressive teeth wear. The effects of continuous exposure to industrial noise, a “stressor” agent, cannot be ignored and its effects on the teeth must be evaluated. Aims: The aim of this study was to ascertain the effects of industrial noise on dental wear over time, by identifying and quantifying crown area loss. Material and Methods: 39 Wistar rats were used. Thirty rats were divided in 3 experimental groups of 10 animals each. Animals were exposed to industrial noise, rich in LFN components, for 1, 4 and 7 months, with an average weekly exposure of 40 hours (8h/day, 5 days/week with the weekends in silence). The remaining 9 animals were kept in silence. The areas of the three main cusps of the molars were measured under light microscopy. Statistical analysis used: A two-way ANOVA model was applied at significance level of 5%. Results: The average area of the molar cusps was significantly different between exposed and non-exposed animals. The most remarkable differences occurred between month 1 and 4. The total crown loss from month 1 to month 7 was 17.3% in the control group, and 46.5% in the exposed group, and the differences between these variations were significant (p<0.001). Conclusions: Our data suggest that industrial noise is an important factor in the pathogenesis of tooth wear. PMID:25798052

  10. Cancer promotion in a mouse-skin model by a 60-Hz magnetic field: I. Experimental design and exposure system

    SciTech Connect

    Stuchly, M.A.; Lecuyer, D.W.; McLean, J. )

    1991-01-01

    The rationale for selection of an animal model, the experimental design, and the design and evaluation of an exposure system used in studies of 60-Hz magnetic fields are described. The studies were conceived to assay development of cancer and immune responsiveness in mice exposed to magnetic fields. The exposure system utilized a quadrupole-coil configuration to minimize stray magnetic fields. Four square-wound coil provided a uniform field within a volume occupied by 16 animal cages. The magnetic field had a mean flux density of 2 mT that varied less than {plus minus} 10% within the volume occupied by animals' cages. The flux density decreased to less than 0.1 microT at a distance of 2 m from the coils. In each exposure system 32 animals could be housed in plastic cages.

  11. Experimental determination of safe atmospheric exposure concentrations of JP-10 jet fuel. Final technical report

    SciTech Connect

    Haun, C.C.; Kinkead, E.R.; Vernot, E.H.; MacEwen, J.D.; Bruner, R.H.

    1985-11-01

    Four animal species were exposed for 1 year to 100 ppm (556 cu mg/m) JP-10 to determine its long-term toxic and oncogenic effects. Rats, mice, and hamsters were maintained for 1 year poste posure, while dogs were held for 5 years post exposure. Mean body weights of exposed hamsters and make rats were lower than controls during exposure. Weight recovery occurred in hamsters, but not in male rats during post exposure phase of the study. Significant JP-10 exposure-related effects were renal tubular nephrosis together with an increase in benign and malignant renal-cell tumors in male rats.

  12. Behavioral Outcomes of Young Children with Prenatal Exposure to Alcohol: Review and Analysis of Experimental Literature.

    ERIC Educational Resources Information Center

    Williams, Rosanne C.; Carta, Judith J.

    1996-01-01

    Analysis of 51 studies of developmental effects of prenatal exposure to alcohol in children from birth to 72 months found that, although adverse outcomes were found within each domain, age grouping, and exposure category, they comprised fewer than 50% of all outcomes measured. Most adverse outcomes were found in the neurobehavioral domain with…

  13. [Experimental study of proflavine acetate phototransformation processes].

    PubMed

    Zholdakova, Z I; Sinitsyna, O O; Lebedev, A T; Kharchevnikova, N V

    2009-01-01

    Changes in proflavine acetate phototransformation processes upon exposure to visible-range irradiation were studied by high performance liquid chromatography. Proflavine acetate was offered as a photosensitizer during photodynamic water disinfection. Dye transformation products upon time-varying exposure to irradiation were identified. By using structure-activity relationships and information from toxicity databases, the authors evaluated the hazard of the identified products and identified the most hazardous ones.

  14. Pathologic changes associated with experimental exposure of rats to coal dust

    SciTech Connect

    Busch, R.H.; Filipy, R.E.; Karagianes, M.T.; Palmer, R.F.

    1981-02-01

    Male Wistar rats were exposed to bituminous coal dust considered to have high potential for induction of coal workers' pneumoconiosis. They developed lesions similar to simple CWP as described in human subjects. Comparable lesions observed were macules which were of increased size, altered shape, and increased density in animals experiencing chronic exposures. More advanced lesion types, i.e., micronodule, macronodule, silicotic nodule, Caplan's lesion, and infective granuloma, were not observed in the experimental animals. Focal bronchiolization occurred in animals receiving at least 20 months' exposure. In the literature reviewed, this pathologic change is not described as a component of CWP.

  15. Assessment of exposure to TDI and MDI during polyurethane foam production in Poland using integrated theoretical and experimental data.

    PubMed

    Kupczewska-Dobecka, Małgorzata; Czerczak, Sławomir; Brzeźnicki, Sławomir

    2012-09-01

    The aim of this study was to develop an optimal strategy for the assessment of inhalation exposure to isocyanates such as TDI and MDI in the production of polyurethane foam by integration of theoretical and experimental data. ECETOC TRA and EASE predictive models were used to determine the estimated levels of exposure to isocyanates. The results of our study suggest that both applications EASE and ECETOC TRA can be used as a screening 1st Tier tool in this case study. PROC12 ECETOC TRA category can be linked to exposure on TDI during polyurethane foam manufacturing because it is working properly and exceeds 90th percentile measured concentration with factor 3 and the maximum measured value with factor 1, 5. The value estimated by using category PROC2 is underestimated so this category should not be linked to this scenario. At the same time, the applications of EASE overstate the expected concentrations although the scenario "Use in closed process" seems to underestimate the exposure at the "lower end". For MDI the both models estimate exposure in a conservative manner.

  16. INFLUENCE OF EXPOSURE ASSESSMENT METHOD IN AN EPIDEMIOLOGIC STUDY OF TRIHALOMETHANE EXPOSURE AND SPONTANEOUS ABORTION

    EPA Science Inventory

    Trihalomethanes are common contaminants of chlorinated drinking water. Studies of their health effects have been hampered by exposure misclassification, due in part to limitations inherent in using utility sampling records. We used two exposure assessment methods, one based on ut...

  17. INFLUENCE OF EXPOSURE ASSESSMENT METHOD IN AN EPIDEMIOLOGIC STUDY OF TRIHALOMETHANE EXPOSURE AND SPONTANEOUS ABORTION

    EPA Science Inventory

    Trihalomethanes are common contaminants of chlorinated drinking water. Studies of their health effects have been hampered by exposure misclassification, due in part to limitations inherent in using utility sampling records. We used two exposure assessment methods, one based on ut...

  18. Virtual Reality Exposure and Imaginal Exposure in the Treatment of Fear of Flying: A Pilot Study

    ERIC Educational Resources Information Center

    Rus-Calafell, Mar; Gutierrez-Maldonado, Jose; Botella, Cristina; Banos, Rosa M.

    2013-01-01

    Fear of flying (FF) is an impairing psychological disorder that is extremely common in developed countries. The most effective treatment for this particular type of phobia is exposure therapy. However, there are few studies comparing imaginal exposure (IE) and virtual reality (VR) exposure for the treatment of FF. The present study compared the…

  19. Virtual Reality Exposure and Imaginal Exposure in the Treatment of Fear of Flying: A Pilot Study

    ERIC Educational Resources Information Center

    Rus-Calafell, Mar; Gutierrez-Maldonado, Jose; Botella, Cristina; Banos, Rosa M.

    2013-01-01

    Fear of flying (FF) is an impairing psychological disorder that is extremely common in developed countries. The most effective treatment for this particular type of phobia is exposure therapy. However, there are few studies comparing imaginal exposure (IE) and virtual reality (VR) exposure for the treatment of FF. The present study compared the…

  20. REPEATED EXPOSURE TO EXPERIMENTAL PAIN DIFFERENTIATES COMBAT TBI WITH AND WITHOUT PTSD.

    PubMed

    Strigo, Irina A; Spadoni, Andrea D; Inslicht, Sabra S; Simmons, Alan N

    2017-09-20

    Mild traumatic brain injury(mTBI) and posttraumatic stress disorder(PTSD) are highly comorbid conditions that often co-occur with chronic pain. We have shown that women with PTSD following intimate partner violence show attenuated brain response to repeated experimental pain that was related to symptoms of avoidance. The aim of this study was to extend our prior findings to males with combat trauma and to examine brain response to experimental pain in men with and without PTSD who sustained mTBI during combat. Seventy male Veterans performed an experimental pain paradigm during fMRI. Of the 70 total subjects, 46 self-reported a history of mTBI during combat(46/70). Of those with mTBI, 26 also met criteria for PTSD(26/46) .  As in our prior study, we examined change in brain activity to repeated heat pain with linear mixed effects modeling for group by administration interaction effects. We observed a significant group by administration interaction to repeated heat pain within insular, frontal and parietal cortices such that the control group showed increased activation over time, while mTBI groups(mTBI-only, mTBI+PTSD) showed decreased activation within bilateral anterior insulas(AI) between administrations. Importantly, change in the right AI response was inversely correlated with avoidance symptoms, but only in those with co-morbid mTBI+PTSD. Furthermore, in the comorbid group greater AI attenuation was associated with decreased connectivity with anterior cingulate(ACC). The current study provides further evidence that repeated exposure to brief painful stimuli results in attenuation of insula activation over time in traumatized individuals. Furthermore, in PTSD, AI shows greatest attenuation in those with the highest level of avoidance - a finding that was replicated across diverse samples.  Thus, this mechanism may be a generalized mechanism of maladaptive response to experimental pain in those with significant trauma.

  1. Experimental study of relationship between biological hazards of low-dose radiofrequency exposure and energy flow density in Spirostomum ambiguum infusoria exposed at a mobile connection frequency (1 GHz).

    PubMed

    Sarapultseva, E I; Igolkina, J V

    2011-08-01

    Radiofrequency exposure at the mobile connection frequency (1 GHz) at different energy flow densities, 5 μW/cm(2)(2-fold below the maximum permissible level) and 50 μW/cm(2)(5-fold surpassing this level), caused a reduction of motor activity in unicellular hydrobionts Spirostomum ambiguum Ehrbg infusoria. In all cases, the effect was similar by the intensity and developed in a jump-wise manner after exposure of a certain duration, after which did not increase with prolongation of the exposure. The duration of radiofrequency exposure safe for the object varied significantly: 8-9 h and 10 min at 5 and 50 μW, respectively. These innovation data on harmful biological effects of very low radiofrequency exposure (5 μW/cm(2)), the threshold form of biological reaction, presence of "safe" periods of exposure, and the data demonstrating a clear-cut relationship between these periods and energy flow density are interesting from theoretical viewpoint and in connection with the problem of evaluating permissible levels of radiofrequency exposure of biological objects.

  2. Experimental Methods for Studying Generations.

    ERIC Educational Resources Information Center

    Wieting, Stephen G.

    This paper represents two intentions: to discuss the need for theoretical advance in generational studies, and to make suggestions about expanding the design repertoire of generational studies in the interests of these theory developments. First, because generational phenomena on the face seem intransigent to experiment, a comment on…

  3. Susceptibility of Koi and Yellow Perch to infectious hematopoietic necrosis virus by experimental exposure

    USGS Publications Warehouse

    Palmer, Alexander D.; Emmenegger, Eveline J.

    2014-01-01

    Infectious hematopoietic necrosis virus (IHNV) is a novirhabdoviral pathogen that originated in western North America among anadromous Pacific salmonids. Severe disease epidemics in the late 1970s resulting from IHNV's invasion into farmed Rainbow Trout Oncorhynchus mykiss in North America, Asia, and Europe emphasized IHNV's ability to adapt to new hosts under varying rearing conditions. Yellow Perch Perca flavescens and Koi Carp Cyprinus carpio (hereafter, “Koi”) are aquaculture-reared fish that are highly valued in sport fisheries and the ornamental fish trade, respectively, but it is unknown whether these fish species are vulnerable to IHNV infection. In this study, we exposed Yellow Perch, Koi, and steelhead (anadromous Rainbow Trout) to IHNV by intraperitoneal injection (106 PFU/fish) and by immersion (5.7×105 PFU/mL) for 7 h, and monitored fish for 28 d. The extended immersion exposure and high virus concentrations used in the challenges were to determine if the tested fish had any level of susceptibility. After experimental exposure, Yellow Perch and Koi experienced low mortality (35%). Virus was found in dead fish of all species tested and in surviving Yellow Perch by plaque assay and quantitative reverse transcription polymerase chain reaction (qPCR), with a higher prevalence in Yellow Perch than Koi. Infectious virus was also detected in Yellow Perch out to 5 d after bath challenge. These findings indicate that Yellow Perch and Koi are highly resistant to IHNV disease under the conditions tested, but Yellow Perch are susceptible to infection and may serve as possible virus carriers.

  4. Susceptibility of Koi and Yellow Perch to infectious hematopoietic necrosis virus by experimental exposure.

    PubMed

    Palmer, Alexander D; Emmenegger, Eveline J

    2014-06-01

    Infectious hematopoietic necrosis virus (IHNV) is a novirhabdoviral pathogen that originated in western North America among anadromous Pacific salmonids. Severe disease epidemics in the late 1970s resulting from IHNV's invasion into farmed Rainbow Trout Oncorhynchus mykiss in North America, Asia, and Europe emphasized IHNV's ability to adapt to new hosts under varying rearing conditions. Yellow Perch Perca flavescens and Koi Carp Cyprinus carpio (hereafter, "Koi") are aquaculture-reared fish that are highly valued in sport fisheries and the ornamental fish trade, respectively, but it is unknown whether these fish species are vulnerable to IHNV infection. In this study, we exposed Yellow Perch, Koi, and steelhead (anadromous Rainbow Trout) to IHNV by intraperitoneal injection (10(6) PFU/fish) and by immersion (5.7×10(5) PFU/mL) for 7 h, and monitored fish for 28 d. The extended immersion exposure and high virus concentrations used in the challenges were to determine if the tested fish had any level of susceptibility. After experimental exposure, Yellow Perch and Koi experienced low mortality (<6%) compared with steelhead (>35%). Virus was found in dead fish of all species tested and in surviving Yellow Perch by plaque assay and quantitative reverse transcription polymerase chain reaction (qPCR), with a higher prevalence in Yellow Perch than Koi. Infectious virus was also detected in Yellow Perch out to 5 d after bath challenge. These findings indicate that Yellow Perch and Koi are highly resistant to IHNV disease under the conditions tested, but Yellow Perch are susceptible to infection and may serve as possible virus carriers.

  5. FURTHER STUDIES IN EXPERIMENTAL ATHEROSCLEROSIS

    PubMed Central

    Adler, I.

    1917-01-01

    by the very extensive but more or less intermittent blocking of the pulmonary circulation by the oil. The musculature of the artery appears to be the main force applied to overcome the resistance in the circulation. In no case has hypertrophy of the right heart been found. The lesions in the pulmonary arteries of the dogs produced experimentally are closely analogous to atherosclerosis of the human pulmonary artery. PMID:19868168

  6. A Crew Exposure Study. Volume I. Offshore.

    DTIC Science & Technology

    1982-03-15

    AD-Alil 178 A CREW EXPOSURE STUDY VOLUME I OFFSNORE(U) SOUTHWEST- 1/4 RESEARCH INST SAN ANTONIO TX ENGINEERING SCIENCES DIV U J ASTLEFORD ET AL. 5...Research Institute Division of Engineering Sciences 11. Contract or Grant No. P. 0. Drawer 28510 DOT-CG23-80-C-20015 San Antonio, Texas 78284 13. Type of...accumulated gas in gas compressor rooms as a result of fugitive emissions from the compressor and fuel gas engine . The accumulated information from this

  7. An experimental system for controlled exposure of biological samples to electrostatic discharges.

    PubMed

    Marjanovič, Igor; Kotnik, Tadej

    2013-12-01

    Electrostatic discharges occur naturally as lightning strokes, and artificially in light sources and in materials processing. When an electrostatic discharge interacts with living matter, the basic physical effects can be accompanied by biophysical and biochemical phenomena, including cell excitation, electroporation, and electrofusion. To study these phenomena, we developed an experimental system that provides easy sample insertion and removal, protection from airborne particles, observability during the experiment, accurate discharge origin positioning, discharge delivery into the sample either through an electric arc with adjustable air gap width or through direct contact, and reliable electrical insulation where required. We tested the system by assessing irreversible electroporation of Escherichia coli bacteria (15 mm discharge arc, 100 A peak current, 0.1 μs zero-to-peak time, 0.2 μs peak-to-halving time), and gene electrotransfer into CHO cells (7 mm discharge arc, 14 A peak current, 0.5 μs zero-to-peak time, 1.0 μs peak-to-halving time). Exposures to natural lightning stroke can also be studied with this system, as due to radial current dissipation, the conditions achieved by a stroke at a particular distance from its entry are also achieved by an artificial discharge with electric current downscaled in magnitude, but similar in time course, correspondingly closer to its entry. © 2013.

  8. AN APPROACH TO METHODS DEVELOPMENT FOR HUMAN EXPOSURE ASSESSMENT STUDIES

    EPA Science Inventory

    Human exposure assessment studies require methods that are rapid, cost-effective and have a high sample through-put. The development of analytical methods for exposure studies should be based on specific information for individual studies. Human exposure studies suggest that di...

  9. AN APPROACH TO METHODS DEVELOPMENT FOR HUMAN EXPOSURE ASSESSMENT STUDIES

    EPA Science Inventory

    Human exposure assessment studies require methods that are rapid, cost-effective and have a high sample through-put. The development of analytical methods for exposure studies should be based on specific information for individual studies. Human exposure studies suggest that di...

  10. [Experimental studies in Polish psychiatric journals].

    PubMed

    Małyszczak, Krzysztof; Sieradzki, Adrian; Kiejna, Andrzej

    2003-01-01

    Scientific studies in psychiatry from a methodological point of view could be divided into correlational and experimental. Experimental studies are based on active selection of independent and dependent variables, attributing values of the independent variable to persons under study and measuring values of dependent variables. An example of the experimental study is a comparison of two therapeutic methods. Experiments are feeble to selection, informational and confounding bias. This review comprises experimental papers published in journals: "Psychiatria Polska", "Postepy Psychiatrii i Neurologii", "Farmakoterapia w Psychiatrii i Neurologii", "Rocznik Psychogeriatryczny", "Wiadomości Psychiatryczne" oraz "Alkoholizm i Narkomania" from January 1998 to December 2002. 11 experimental publications, 6 randomised, 2 probably randomised and 3 case-control studies were found. The smallest study included 14 persons, the largest 180 persons. The number of experimental groups varied from 2 to 4. 9 studies evaluated features of specific methods of therapy and rehabilitation, among them 6 evaluated efficacy of medications. 2 studies evaluated relations between psychopathological and physiological variables. Experiments were based on groups of patients with a diagnosis of schizophrenia (3), alcohol and drug dependence (2), depression (3), insomnia (1), bronchial asthma (1), and hypertension (1). The review showed that experimental studies do not form a main-stream in Polish psychiatric journals.

  11. Examination of Different Exposure Metrics in an Epidemiological Study

    EPA Science Inventory

    Epidemiological studies of air pollution have traditionally relied upon measurements of ambient concentration from central-site monitoring stations as surrogates of population exposures. However, depending on the epidemiological study design, this approach may introduce exposure...

  12. Examination of Different Exposure Metrics in an Epidemiological Study

    EPA Science Inventory

    Epidemiological studies of air pollution have traditionally relied upon measurements of ambient concentration from central-site monitoring stations as surrogates of population exposures. However, depending on the epidemiological study design, this approach may introduce exposure...

  13. Experimental study of visual accommodation

    NASA Technical Reports Server (NTRS)

    Cornsweet, T. N.; Crane, H. D.

    1972-01-01

    A summary report of a research effort related to the human visual accommodation system is presented. A theoretical study of the accommodation system was made. Subsequent effort was aimed at the development of specialized instrumentation for experiments designed to lead to understanding the nature of the control system in human accommodation. The necessary instrumentation consisted primarily of: (1) an automatic optometer to measure the state of eye focus, (2) a focus stimulator device to control the apparent optical distance to any target, and (3) a two-dimensional eye tracker. The concepts and designs of the first two instruments have been published in the open literature, but this report contains the first detailed treatment of the Purkinje eye tracker developed under this program. The report also discusses an accommodation lag model to explain the ability of the eye to apparently know the polarity of focus error even though the blur on the retina is to a first-approximation an even function. The interaction of the accommodation and eye movement systems is also discussed, as is the ability to train the visual accommodation system to a surprisingly responsive condition in only a few hours of training.

  14. Study of heat exposure during Hajj (pilgrimage).

    PubMed

    Noweir, Madbuli H; Bafail, Abdullah O; Jomoah, Ibrahim M

    2008-12-01

    Heat stress presents a main problem to Muslim Hajeej (pilgrims) during Hajj (pilgrimage) season, particularly in summer. Records of the Saudi Ministry of Health show close relation between heat casualties and climatic heat load through consequent Hajj seasons. The present study was conducted to evaluate the climatic heat load in Hajj locations during summer of 1995 as well as just before and during the Hajj season of 1997. Heat measurements including: T (a), T (w), T (g), WBGT, relative humidity and air velocity were conducted through July-September 1995, and on March/April 1997, in 10 Hajj locations at morning, noon, afternoon and night. The highest WBGTs were at Haram court, Ghazzah area and Muna housing area, followed by Arafat areas and Muzdalefah, and the lowest at Azizia area. However, all the WBGTs were considerably higher than the ACGIH-TLV for safe heat exposure, particularly during daytime; meanwhile, heat exposure considerably exceeded the ASHRAE comfort zone at all locations all times. The natural climatic condition is a major contributing factor to the overall heat load; moreover, potentiated by heat dissipated from Hajj activities, including Hajeej crowds, human activities, and the vehicles' masses exhaust. This situation is further synergized by some pilgrims' misbehavior (e.g. living in open sunny areas, using vehicles without roofs) and lack of awareness of the seriousness of heat exposure among them. An outline for a control strategy has been suggested based on planting open areas of Arafat and Muna, provision of air conditioned housing and tents in Muna, segregation of pedestrians from vehicles and their provision of shaded roads and rest areas, establishing more water spatters in Arafat and Muna, checking the performance of large vehicles before issuing their permits for operation during Hajj, providing vehicles parking isolated areas away from Hajeej tents, provision of ample amounts of quality drinking water in all Hajj locations, provision of

  15. Farm Family Exposure Study: methods and recruitment practices for a biomonitoring study of pesticide exposure.

    PubMed

    Baker, Beth A; Alexander, Bruce H; Mandel, Jack S; Acquavella, John F; Honeycutt, Richard; Chapman, Pamela

    2005-11-01

    The Farm Family Exposure Study was initiated to characterize pesticide exposure to farm family members around the time of one pesticide application in a manner that will facilitate exposure assessment in epidemiologic studies of pesticides. A sample of farm families with children was recruited by randomly selecting farmers from lists of licensed pesticide applicators in Minnesota and South Carolina. Eligible families were selected from among those who planned to apply one of three chemicals, glyphosate, 2,4-D, or chlorpyrifos, as part of their normal operations. The applicator, spouse, and all children in the family ages 4-17 years were included in the study. The applicator and spouse completed self-administered questionnaires addressing demographics, farming practices and potential exposures to them and their children. Field observers documented the application, recorded application practices, equipment, potential exposures, and the presence of children or spouses in the immediate vicinity of pesticide activities. All study participants were asked to collect each urine void for 5 days, 1 day before through 3 days after the application. Pesticides were measured in 24-h composite urine samples with a one part per billion limit of detection. Of 11,164 applicators screened, 994 families met the inclusion criteria. Of these, 95 families were enrolled. Enrollees were similar in most characteristics to their peers who were not participants in the study. In total, there were 106 applications, 10 of which involved more than one chemical. This resulted in urinary data for 48 farmers and spouses and their 79 children for glyphosate, 34 farmers and spouses and their 50 children for chlorpyrifos, and 34 farmers and spouses and their 53 children for 2,4-D. Compliance with the 24-h urine collection was particularly good for the adult participants. There were more missing samples for children than for adults, but overall compliance was high. The Farm Family Exposure Study should

  16. Visual exposure to obesity: Experimental effects on attraction toward overweight men and mate choice in females.

    PubMed

    Robinson, E; Christiansen, P

    2015-09-01

    Cultural differences in ideal body weight are well established, but less research has examined attraction toward potential mates of heavier body weights. We examined whether exposure to obesity increases physical attraction toward overweight men. In Studies 1 and 2, we examined the effect that exposure to obese vs healthy weight men had on female attraction toward an overweight man. Study 3 examined whether females who are regularly exposed to males of heavier body weights reported a greater attraction toward overweight men. Study 4 tested whether females in an online dating study were more likely to choose to date an overweight man, after having been exposed to obesity. Exposure to obesity altered visual perceptions of what normal and therefore healthy body weights were and this resulted in greater attraction toward an overweight man (Studies 1 and 2). Females regularly exposed to men of heavier body weight reported a greater attraction toward overweight men (Study 3). After exposure to obesity, females in an online dating study were more likely to choose to date an overweight man ahead of a healthy weight man (Study 4). Exposure to male obesity increases female attraction toward overweight men and may affect mate choice.

  17. THE 1998 BALTIMORE PARTICULATE MATTER EPIDEMIOLOGY-EXPOSURE STUDY: PART 2-PERSONAL EXPOSURE ASSESSMENT ASSOCIATED WITH AN ELDERLY STUDY POPULATION

    EPA Science Inventory

    An integrated epidemiological-exposure panel study was conducted during the summer of 1998 which focused upon establishing relationships between potential human exposures to particulate matter (PM) and related co-pollutants with detectable health effects. The study design incor...

  18. THE 1998 BALTIMORE PARTICULATE MATTER EPIDEMIOLOGY-EXPOSURE STUDY: PART 2-PERSONAL EXPOSURE ASSESSMENT ASSOCIATED WITH AN ELDERLY STUDY POPULATION

    EPA Science Inventory

    An integrated epidemiological-exposure panel study was conducted during the summer of 1998 which focused upon establishing relationships between potential human exposures to particulate matter (PM) and related co-pollutants with detectable health effects. The study design incor...

  19. Psychiatric epidemiologic study of occupational lead exposure

    SciTech Connect

    Parkinson, D.K.; Ryan, C.; Bromet, E.J.; Connell, M.M.

    1986-02-01

    The association of occupational lead exposure with neuropsychiatric functioning was evaluated using data collected in 1982 in eastern Pennsylvania from 288 lead-exposed workers and 181 nonexposed subjects. Both current and cumulative exposure indices were used. After controlling for age, education, and income, few meaningful differences between exposed and control workers were found on either neuropsychologic or psychosocial variables. Dose-response analyses indicated that among lead-exposed workers, cumulative and current exposure were unrelated to neuropsychologic performance. The only meaningful associations occurred between exposure and level of conflict in interpersonal relationships. The results thus give evidence against hypotheses suggesting adverse neuropsychologic effects.

  20. ALVEOLAR BREATH SAMPLING AND ANALYSIS IN HUMAN EXPOSURE ASSESSMENT STUDIES

    EPA Science Inventory

    Alveolar breath sampling and analysis can be extremely useful in exposure assessment studies involving volatile organic compounds (VOCs). Over recent years scientists from the EPA's National Exposure Research Laboratory have developed and refined an alveolar breath collection ...

  1. USE OF EXHALED BREATH CONDENSATE IN A HUMAN EXPOSURE STUDY

    EPA Science Inventory

    Exhaled breath condensate (EBC) is a noninvasive, repeatable collection technique to sample biomarkers of lung inflammation, oxidative stress, and environmental exposure. It is unclear whether EBC is an effective tool in human environmental exposure studies with multi-day samplin...

  2. USE OF EXHALED BREATH CONDENSATE IN A HUMAN EXPOSURE STUDY

    EPA Science Inventory

    Exhaled breath condensate (EBC) is a noninvasive, repeatable collection technique to sample biomarkers of lung inflammation, oxidative stress, and environmental exposure. It is unclear whether EBC is an effective tool in human environmental exposure studies with multi-day samplin...

  3. ALVEOLAR BREATH SAMPLING AND ANALYSIS IN HUMAN EXPOSURE ASSESSMENT STUDIES

    EPA Science Inventory

    Alveolar breath sampling and analysis can be extremely useful in exposure assessment studies involving volatile organic compounds (VOCs). Over recent years scientists from the EPA's National Exposure Research Laboratory have developed and refined an alveolar breath collection ...

  4. EXPOSURE ASSESSMENT METHODS DEVELOPMENT PILOTS FOR THE NATIONAL CHILDREN'S STUDY

    EPA Science Inventory

    Accurate exposure classification tools are needed to link exposure with health effects. EPA began methods development pilot studies in 2000 to address general questions about exposures and outcome measures. Selected pilot studies are highlighted in this poster. The “Literature Re...

  5. EXPOSURE ASSESSMENT METHODS DEVELOPMENT PILOTS FOR THE NATIONAL CHILDREN'S STUDY

    EPA Science Inventory

    Accurate exposure classification tools are needed to link exposure with health effects. EPA began methods development pilot studies in 2000 to address general questions about exposures and outcome measures. Selected pilot studies are highlighted in this poster. The “Literature Re...

  6. Urinary Polycyclic Aromatic Hydrocarbon Metabolites as Biomarkers to Woodsmoke Exposure – Results from a Controlled Exposure Study

    PubMed Central

    Li, Zheng; Trinidad, Debra; Pittman, Erin N.; Riley, Erin A.; Sjodin, Andreas; Dills, Russell L.; Paulsen, Michael; Simpson, Christopher D.

    2015-01-01

    Woodsmoke contains harmful components—such as fine particulate matter (PM2.5) and polycyclic aromatic hydrocarbons (PAHs)—and impacts more than half of the global population. We investigated urinary hydroxylated PAH metabolites (OH-PAHs) as woodsmoke exposure biomarkers in nine non-smoking volunteers experimentally exposed to a wood fire. Individual urine samples were collected from 24-h before to 48-h after the exposure and personal PM2.5 samples were collected during the 2-h woodsmoke exposure. Concentrations of nine OH-PAHs increased by 1.8–7.2 times within 2.3–19.3 h, and returned to baseline approximately 24 h after the exposure. 2-Naphthol (2-NAP) had the largest post-exposure increase and exhibited a clear excretion pattern in all participants. The level of urinary OH-PAHs, except 1-hydroxypyrene (1-PYR), correlated with those of PM2.5, levoglucosan and PAHs in personal PM2.5 samples. This finding suggests that several urinary OH-PAHs, especially 2-NAP, are potential exposure biomarkers to woodsmoke; by contrast, 1-PYR may not be a suitable biomarker. Compared to levoglucosan and methoxyphenols–two other urinary woodsmoke biomarkers that were measured in the same study and reported previously–OH-PAHs might be better biomarkers based on sensitivity, robustness and stability, particularly under suboptimal sampling and storage conditions, like in epidemiological studies carried out in less-developed areas. PMID:25605446

  7. Immunotoxicology of arc welding fume: worker and experimental animal studies.

    PubMed

    Zeidler-Erdely, Patti C; Erdely, Aaron; Antonini, James M

    2012-01-01

    Arc welding processes generate complex aerosols composed of potentially hazardous metal fumes and gases. Millions of workers worldwide are exposed to welding aerosols daily. A health effect of welding that is of concern to the occupational health community is the development of immune system dysfunction. Increased severity, frequency, and duration of upper and lower respiratory tract infections have been reported among welders. Specifically, multiple studies have observed an excess mortality from pneumonia in welders and workers exposed to metal fumes. Although several welder cohort and experimental animal studies investigating the adverse effects of welding fume exposure on immune function have been performed, the potential mechanisms responsible for these effects are limited. The objective of this report was to review both human and animal studies that have examined the effect of welding fume pulmonary exposure on local and systemic immune responses.

  8. Immunotoxicology of arc welding fume: Worker and experimental animal studies

    PubMed Central

    Zeidler-Erdely, Patti C.; Erdely, Aaron; Antonini, James M.

    2015-01-01

    Arc welding processes generate complex aerosols composed of potentially hazardous metal fumes and gases. Millions of workers worldwide are exposed to welding aerosols daily. A health effect of welding that is of concern to the occupational health community is the development of immune system dysfunction. Increased severity, frequency, and duration of upper and lower respiratory tract infections have been reported among welders. Specifically, multiple studies have observed an excess mortality from pneumonia in welders and workers exposed to metal fumes. Although several welder cohort and experimental animal studies investigating the adverse effects of welding fume exposure on immune function have been performed, the potential mechanisms responsible for these effects are limited. The objective of this report was to review both human and animal studies that have examined the effect of welding fume pulmonary exposure on local and systemic immune responses. PMID:22734811

  9. Exposure Measurement Error in PM2.5 Health Effects Studies: A Pooled Analysis of Eight Personal Exposure Validation Studies

    EPA Science Inventory

    Background: Exposure measurement error is a concern in long-term PM2.5 health studies using ambient concentrations as exposures. We assessed error magnitude by estimating calibration coefficients as the association between personal PM2.5 exposures from validation studies and typ...

  10. Exposure Measurement Error in PM2.5 Health Effects Studies: A Pooled Analysis of Eight Personal Exposure Validation Studies

    EPA Science Inventory

    Background: Exposure measurement error is a concern in long-term PM2.5 health studies using ambient concentrations as exposures. We assessed error magnitude by estimating calibration coefficients as the association between personal PM2.5 exposures from validation studies and typ...

  11. The Australian Work Exposures Study: Occupational Exposure to Polycyclic Aromatic Hydrocarbons.

    PubMed

    Driscoll, Timothy R; Carey, Renee N; Peters, Susan; Glass, Deborah C; Benke, Geza; Reid, Alison; Fritschi, Lin

    2016-01-01

    The aims of this study were to produce a population-based estimate of the prevalence of work-related exposure to polycyclic aromatic hydrocarbons (PAHs), to identify the main circumstances of exposure and to describe the use of workplace control measures designed to decrease those exposures. The analysis used data from the Australian Workplace Exposures Study, a nationwide telephone survey which investigated the current prevalence and exposure circumstances of work-related exposure to 38 known or suspected carcinogens, including PAHs, among Australian workers aged 18-65 years. Using the web-based tool OccIDEAS, semi-quantitative information was collected about exposures in the current job held by the respondent. Questions were addressed primarily at tasks undertaken rather than about self-reported exposures. Of the 4,993 included respondents, 297 (5.9%) were identified as probably being exposed to PAHs in their current job [extrapolated to 6.7% of the Australian working population-677 000 (95% confidence interval 605 000-757 000) workers]. Most (81%) were male; about one-third were farmers and about one-quarter worked in technical and trades occupations. In the agriculture industry about half the workers were probably exposed to PAHs. The main exposure circumstances were exposure to smoke through burning, fighting fires or through maintaining mowers or other equipment; cleaning up ash after a fire; health workers exposed to diathermy smoke; cooking; and welding surfaces with a coating. Where information on control measures was available, their use was inconsistent. Workers are exposed to PAHs in many different occupational circumstances. Information on the exposure circumstances can be used to support decisions on appropriate priorities for intervention and control of occupational exposure to PAHs, and estimates of burden of cancer arising from occupational exposure to PAHs. © The Author 2015. Published by Oxford University Press on behalf of the British

  12. The Australian Work Exposures Study: Prevalence of Occupational Exposure to Formaldehyde.

    PubMed

    Driscoll, Timothy R; Carey, Renee N; Peters, Susan; Glass, Deborah C; Benke, Geza; Reid, Alison; Fritschi, Lin

    2016-01-01

    The aims of this study were to produce a population-based estimate of the prevalence of work-related exposure to formaldehyde, to identify the main circumstances of exposure and to describe the use of workplace control measures designed to decrease those exposures. The analysis used data from the Australian Workplace Exposures Study, a nationwide telephone survey, which investigated the current prevalence and exposure circumstances of work-related exposure to 38 known or suspected carcinogens, including formaldehyde, among Australian workers aged 18-65 years. Using the web-based tool OccIDEAS, semi-quantitative information was collected about exposures in the current job held by the respondent. Questions were addressed primarily at tasks undertaken rather than about self-reported exposures. Of the 4993 included respondents, 124 (2.5%) were identified as probably being exposed to formaldehyde in the course of their work [extrapolated to 2.6% of the Australian working population-265 000 (95% confidence interval 221 000-316 000) workers]. Most (87.1%) were male. About half worked in technical and trades occupations. In terms of industry, about half worked in the construction industry. The main circumstances of exposure were working with particle board or plywood typically through carpentry work, building maintenance, or sanding prior to painting; with the more common of other exposures circumstances being firefighters involved in fighting fires, fire overhaul, and clean-up or back-burning; and health workers using formaldehyde when sterilizing equipment or in a pathology laboratory setting. The use of control measures was inconsistent. Workers are exposed to formaldehyde in many different occupational circumstances. Information on the exposure circumstances can be used to support decisions on appropriate priorities for intervention and control of occupational exposure to formaldehyde, and estimates of burden of cancer arising from occupational exposure to formaldehyde

  13. Experimental evaluation of skin carcinogenicity associated with chronic exposure to synthetic petroleums

    SciTech Connect

    Holland, J. M.

    1980-01-01

    Most fossil liquids, whether natural or synthetic, possess some degree of skin carcinogenic activity if applied at high enough concentration for sufficient time to genetically responsive experimental animals. Whether a synthetic petroleum shown to be capable of eliciting skin cancer in the mouse will have similar capability in exposed humans depends upon the potency of the material, the dosage and the person's individual susceptibility. This presentation describes the approach being taken to quantitiate skin carcinogenic potency. In addition to potency estimation, exposure conditions that could have an important bearing upon extrapolation of experimental animal data are investigated. These factors include the capacity of the material to induce skin irritation, and physical-chemical characteristics that influence skin localization and persistence of potentially carcinogenic components.

  14. 40 CFR 159.170 - Human epidemiological and exposure studies.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Human epidemiological and exposure... Information § 159.170 Human epidemiological and exposure studies. Information must be submitted which concerns... that a correlation may exist between exposure to a pesticide and observed adverse effects in...

  15. 40 CFR 159.170 - Human epidemiological and exposure studies.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Human epidemiological and exposure... Information § 159.170 Human epidemiological and exposure studies. Information must be submitted which concerns... that a correlation may exist between exposure to a pesticide and observed adverse effects in...

  16. 40 CFR 159.170 - Human epidemiological and exposure studies.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Human epidemiological and exposure... Information § 159.170 Human epidemiological and exposure studies. Information must be submitted which concerns... that a correlation may exist between exposure to a pesticide and observed adverse effects in humans...

  17. USE OF DISPOSABLE DIAPERS TO COLLECT URINE IN EXPOSURE STUDIES

    EPA Science Inventory

    Large studies of children's health as it relates to exposures to chemicals in the environment often require measurements of biomarkers of chemical exposures or effects in urine samples. But collection of urine samples from infants and toddlers is difficult. For large exposure s...

  18. 40 CFR 159.170 - Human epidemiological and exposure studies.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Human epidemiological and exposure... Information § 159.170 Human epidemiological and exposure studies. Information must be submitted which concerns... that a correlation may exist between exposure to a pesticide and observed adverse effects in...

  19. USE OF DISPOSABLE DIAPERS TO COLLECT URINE IN EXPOSURE STUDIES

    EPA Science Inventory

    Large studies of children's health as it relates to exposures to chemicals in the environment often require measurements of biomarkers of chemical exposures or effects in urine samples. But collection of urine samples from infants and toddlers is difficult. For large exposure s...

  20. Air Pollution Exposure Modeling for Health Studies | Science ...

    EPA Pesticide Factsheets

    Dr. Michael Breen is leading the development of air pollution exposure models, integrated with novel personal sensor technologies, to improve exposure and risk assessments for individuals in health studies. He is co-investigator for multiple health studies assessing the exposure and effects of air pollutants. These health studies include participants with asthma, diabetes, and coronary artery disease living in various U.S. cities. He has developed, evaluated, and applied novel exposure modeling and time-activity tools, which includes the Exposure Model for Individuals (EMI), GPS-based Microenvironment Tracker (MicroTrac) and Exposure Tracker models. At this seminar, Dr. Breen will present the development and application of these models to predict individual-level personal exposures to particulate matter (PM) for two health studies in central North Carolina. These health studies examine the association between PM and adverse health outcomes for susceptible individuals. During Dr. Breen’s visit, he will also have the opportunity to establish additional collaborations with researchers at Harvard University that may benefit from the use of exposure models for cohort health studies. These research projects that link air pollution exposure with adverse health outcomes benefit EPA by developing model-predicted exposure-dose metrics for individuals in health studies to improve the understanding of exposure-response behavior of air pollutants, and to reduce participant

  1. Prenatal drug exposure, behavioral problems and drug experimentation among African American urban adolescents

    PubMed Central

    Wang, Yan; Buckingham-Howes, Stacy; Nair, Prasanna; Zhu, Shijun; Magder, Larry; Black, Maureen M.

    2014-01-01

    Purpose To examine how prenatal heroin/cocaine exposure (PDE) and behavioral problems relate to adolescent drug experimentation. Methods The sample included African American adolescents (mean age=14.2 yr, SD=1.2) with PDE (n=73) and a non-exposed community comparison (n=61). PDE status was determined at delivery through toxicology analysis and maternal-report. Internalizing/externalizing problems were assessed during adolescence with the Behavior Assessment System for Children, Second Edition. Drug experimentation was assessed by adolescent-report and urine analysis. Logistic regression evaluated the likelihood of drug experimentation related to PDE and behavioral problems, adjusting for age, gender, prenatal tobacco/alcohol exposure, perceived peer drug use and caregiver drug use. Interaction terms examined gender modification. Results 67 (50%) used drugs. 25 (19%) used tobacco/alcohol only and 42 (31%) used marijuana/illegal drugs. 94 (70%) perceived peer drug use. PDE significantly increased the risk of tobacco/alcohol experimentation (OR=3.07, 95% CI: 1.09–8.66, p=0.034), but not after covariate adjustment (aOR=1.31, 95% CI: 0.39–4.36, p>0.05). PDE was not related to overall or marijuana/illegal drug experimentation. The likelihood of overall drug experimentation was doubled per Standard Deviation (SD) increase in externalizing problems (aOR=2.28, 95% CI: 1.33–3.91, p=0.003) and, among girls, 2.82 times greater (aOR=2.82, 95% CI: 1.34–5.94, p=0.006) per SD increase in internalizing problems. Age and perceived peer drug use were significant covariates. Conclusions Drug experimentation was relatively common (50%), especially in the context of externalizing problems, internalizing problems (girls only), age, and perceived peer drug use. Findings support Problem Behavior Theory and suggest that adolescent drug prevention address behavioral problems and promote prosocial peer groups. PMID:24768161

  2. METHYLMERCURY AND NUTRITION: ADULT EFFECTS OF FETAL EXPOSURE IN EXPERIMENTAL MODELS

    PubMed Central

    Paletz, Elliott M.; Reed, Miranda N.

    2008-01-01

    Human exposure to the life-span developmental neurotoxicant, methylmercury (MeHg), is primarily via the consumption of fish or marine mammals. Fish are also excellent sources of important nutrients, including selenium and n-3 polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA). Laboratory models of developmental MeHg exposure can be employed to assess the roles of nutrients and MeHg and to identify potential mechanisms of action if the appropriate exposure measures are used. In describing chronic exposures, relationships between daily intake and brain mercury are consistent and orderly across species, even when large differences in blood:brain ratios exist. It is well-established that low level developmental MeHg produces sensory deficits. Recent studies also show that perseveration in reversal-learning tasks occurs after gestational exposures that produce low micromolar concentrations in the brain. A no-effect level has not been identified for this effect. These exposures do not affect the acquisition or performance of discrimination learning, set shifting (extra-dimensional shift), or memory. Reversal learning deficits may be related to enhanced impact of reinforcers as measured using progressive ratio reinforcement schedules, an effect that could result in perseveration. Also reported is enhanced sensitivity to dopamine reuptake inhibitors and diminished sensitivity to pentobarbital, a GABAA agonist. Diets rich in PUFAs or selenium do not protect against MeHg's effects on reversal learning but, by themselves, may diminish variability in performance, enhance attention or psychomotor function and may confer some protection against age-related deficits in these areas. It is hypothesized that altered reward processing, dopamine and GABAergic neurotransmitter systems, and cortical regions associated with choice and perseveration are especially sensitive to developmental MeHg at low exposure levels. Human testing for MeHg's neurotoxicity should

  3. Methylmercury and nutrition: adult effects of fetal exposure in experimental models.

    PubMed

    Newland, M Christopher; Paletz, Elliott M; Reed, Miranda N

    2008-09-01

    Human exposure to the life-span developmental neurotoxicant, methylmercury (MeHg), is primarily via the consumption of fish or marine mammals. Fish are also excellent sources of important nutrients, including selenium and n-3 polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA). Laboratory models of developmental MeHg exposure can be employed to assess the roles of nutrients and MeHg and to identify potential mechanisms of action if the appropriate exposure measures are used. When maternal exposure is protracted, relationships between daily intake and brain mercury are consistent and orderly across species, even when large differences in blood:brain ratios exist. It is well established that low-level developmental MeHg produces sensory deficits. Recent studies also show that perseveration in reversal-learning tasks occurs after gestational exposures that produce low micromolar concentrations in the brain. A no-effect level has not been identified for this effect. These exposures do not affect the acquisition or performance of discrimination learning, set shifting (extradimensional shift), or memory. Reversal-learning deficits may be related to enhanced impact of reinforcers as measured using progressive ratio reinforcement schedules, an effect that could result in perseveration. Also reported is enhanced sensitivity to dopamine reuptake inhibitors and diminished sensitivity to pentobarbital, a GABA(A) agonist. Diets rich in PUFAs or selenium do not protect against MeHg's effects on reversal learning but, by themselves, may diminish variability in performance, enhance attention or psychomotor function and may confer some protection against age-related deficits in these areas. It is hypothesized that altered reward processing, dopamine and GABAergic neurotransmitter systems, and cortical regions associated with choice and perseveration are especially sensitive to developmental MeHg at low exposure levels. Human testing for MeHg's neurotoxicity

  4. Bioaccumulation and metallothionein response in the Asiatic clam (Corbicula fluminea) after experimental exposure to cadmium and inorganic mercury

    SciTech Connect

    Baudrimont, M.; Metivaud, J.; Maury-Brachet, R.; Ribeyre, F.; Boudou, A.

    1997-10-01

    The involvement of metallothioneins (MTs) in cadmium (Cd) and inorganic mercury (Hg[II]) bioaccumulation by the freshwater bivalve Corbicula fluminea was experimentally investigated after 0, 15, 30 and 45 d of exposure from the water column source. Three levels of contamination were studied for each metal: 0, 5, and 35 {micro}g Cd/L and 0, 1.45, and 5 {micro}g Hg/L, with two replicates per condition. Forty eight experimental units (EUs) were conducted simultaneously. The mollusks were fed twice a week by additions of phytoplanktonic algae. Quantification of MTs was done by Hg-saturation assay, using cold Hg(II). A partial purification of these proteins was conducted by gel-filtration chromatography, followed by Cd determinations in the different eluted fractions. Results at the whole organism (soft tissues) and organ or tissue group (gills, mantle, foot, visceral mass) levels show high metal concentrations, with a fourfold greater accumulation of inorganic Hg than Cd after 30 d exposure at the same concentration of 5 {micro}g/L. Gills and visceral mass were the principal storage compartments. A significant increase in MT concentrations was revealed in these two organs after exposure to Cd: ratios between the MT concentrations in contaminated and control mollusks were 2.4 and 2.8, respectively, for 5 and 35 {micro}g Cd/L. Cd burdens in the cytosol and in {le}18-kDa protein fractions, similar to purified mammal MTs, correspond to 30 and 14% of the total Cd accumulated in the whole organisms. No significant increase in MT biosynthesis was observed after exposure to inorganic Hg, despite the high metal concentrations in the organs.

  5. Neonatal Idiotypic Exposure Alters Subsequent Cytokine, Pathology, and Survival Patterns in Experimental Schistosoma mansoni Infections

    PubMed Central

    Angela Montesano, M.; Colley, Daniel G.; Eloi-Santos, Silvana; Freeman, George L.; Secor, W. Evan

    1999-01-01

    Exposure to maternal idiotypes (Ids) or antigens might predispose a child to develop an immunoregulated, asymptomatic clinical presentation of schistosomiasis. We have used an experimental murine system to address the role of Ids in this immunoregulation. Sera from mice with 8-wk Schistosoma mansoni infection, chronic (20-wk infection) moderate splenomegaly syndrome (MSS), or chronic hypersplenomegaly syndrome (HSS) were passed over an S. mansoni soluble egg antigen (SEA) immunoaffinity column to prepare Ids (8WkId, MSS Id, HSS Id). Newborn mice were injected with 8WkId, MSS Id, HSS Id, or normal mouse immunoglobulin (NoMoIgG) and infected with S. mansoni 8 wk later. Mice exposed to 8WkId or MSS Id as newborns had prolonged survival and decreased morbidity compared with mice that received HSS Id or NoMoIgG. When stimulated with SEA, 8WkId, or MSS Id, spleen cells from mice neonatally injected with 8WkId or MSS Id produced more interferon γ than spleen cells from mice neonatally injected with HSS Id or NoMoIgG. Furthermore, neonatal exposure to 8WkId or MSS Id, but not NoMoIgG or HSS Id, led to significantly smaller granuloma size and lower hepatic fibrosis levels in infected mice. Together, these results indicate that perinatal exposure to appropriate anti-SEA Ids induces long-term effects on survival, pathology, and immune response patterns in mice subsequently infected with S. mansoni. PMID:9989978

  6. Clinical Outcomes of Occupational Exposure to N,N-Dimethylformamide: Perspectives from Experimental Toxicology

    PubMed Central

    Kim, Tae Hyun

    2011-01-01

    N,N-Dimethylformamide (DMF) is globally used as an organic solvent in the production of synthetic leather and resins because of its low volatility, making it an attractive industrial material. Despite its excellent property as a chemical solvent, utilization of DMF is somewhat controversial nowadays due to its hazardous effects on exposed workers in work places. Many toxification cases are being reported globally and the number of cases of liver damage is still increasing in developing countries. On account of this, a series of epidemiologic surveys are being conducted to understand the degrees of liver damage caused by DMF exposure. Furthermore, many investigations have been performed to clarify the mechanism of DMF-induced liver toxicity using both human and experimental animal models. This review summarizes the current occupational cases reported on liver damage from workers exposed to DMF in industrial work places and the research results that account for DMF-induced liver failure and possible carcinogenesis. The findings reviewed here show the synergistic toxicity of DMF exposure with other toxicants, which might occur through complicated but distinct mechanisms, which may extend our knowledge for establishing risk assessments of DMF exposure in industrial work places. PMID:22953193

  7. An Experimental Study of Thrust Augmenting Ejectors

    DTIC Science & Technology

    1983-12-01

    A , AN EXPERIMENTAL STUDY OF THRUST AUG’XENTING EJECTORS THESIS William D. Lewis Captain 11. S. Army AFIT/GAE/Ai/83D- 13 1 DTIC Li~i ELECTE JANI...83D-13 AN LEPERIMENTAL STUDY OF THRUST AUG-M..TING EJECTORS "l•HSIS William D. Levis Captain U. S. Army AF1T/GAAE/AA/$3D- 13 ’jK Approved for public...release; distribution unliaited I V .,, AFIT/GAE/AA/83D- 13 AN EXPERIMENTAL STUDY OF THRUST AUGMENTING EJECTORS THESIS Presented to *he Faculty of the

  8. Exposure indices for the National Children's Study: application to inhalation exposures in Queens County, NY

    PubMed Central

    Isukapalli, Sastry S.; Brinkerhoff, Christopher J.; Xu, Shu; Dellarco, Michael; Landrigan, Philip J.; Lioy, Paul J.; Georgopoulos, Panos G.

    2014-01-01

    Characterization of environmental exposures to population subgroups within the National Children's Study (NCS), or other large-scale human environmental health studies is essential for developing a high-quality data platform for subsequent investigations. A computational formulation utilizing the tiered exposure ranking framework is presented for calculating inhalation exposure indices (EIs) for population subgroups. This formulation employs a probabilistic approach and combines information from diverse, publicly available exposure-relevant databases and information on biological mechanisms, for ranking study locations or population subgroups with respect to potential for specific end point-related environmental exposures. These EIs capture and summarize, within a set of numerical values/ranges, complex distributions of potential exposures to multiple airborne contaminants. These estimates capture spatial and demographic variability within each study segment, and allow for the relative comparison of study locations based on different statistical metrics of exposures. The EI formulation was applied to characterize and rank segments within Queens County, NY, which is one of the Vanguard centers for the NCS. Inhalation EI estimates relevant to respiratory outcomes, and potentially to pregnancy outcomes (low birth weight and preterm birth rates) were calculated at the study segment level. Results indicate that there is substantial variability across the study segments in Queens County, NY, and within segments, and showed an exposure gradient across the study segments that can help guide and target environmental and personal exposure sampling efforts in this county. The results also serve as an example application of the EI for use in other exposure and outcome studies. PMID:23072768

  9. Effects of Exposure to Ozone on the Ocular Surface in an Experimental Model of Allergic Conjunctivitis

    PubMed Central

    Lee, Hun; Kim, Eung Kweon; Kim, Hee Young; Kim, Tae-im

    2017-01-01

    Based on previous findings that ozone can induce an inflammatory response in the ocular surface of an animal model and in cultured human conjunctival epithelial cells, we investigated whether exposure to ozone exacerbates symptoms of allergic conjunctivitis. We evaluated the effects of exposure to ozone on conjunctival chemosis, conjunctival injection, corneal and conjunctival fluorescein staining scores, production of inflammatory cytokines in tears, and aqueous tear production in a mouse model of allergic conjunctivitis. To validate our in vivo results, we used interleukin (IL)-1α-pretreated conjunctival epithelial cells as an in vitro substitute for the mouse model. We evaluated whether exposure to ozone increased the inflammatory response and altered oxidative status and mitochondrial function in IL-1α-pretreated conjunctival epithelial cells. In the in vivo study, ozone induced increases in conjunctival chemosis, conjunctival injection, corneal and conjunctival fluorescein staining scores, and production of inflammatory cytokines, accompanied by a decrease in tear volume. In the in vitro study, exposure to ozone led to additional increases in IL-6 and tumor necrosis factor-α mRNA levels, which were already induced by treatment with IL-1α. Ozone did not induce any changes in cell viability. Pretreatment with IL-1α increased the expression of manganese superoxide dismutase, and exposure to ozone led to additional increments in the expression of this antioxidant enzyme. Ozone did not induce any changes in mitochondrial activity or expression of mitochondrial enzymes and proteins related to mitochondrial function, with the exception of phosphor-mammalian target of rapamycin. Treatment with butylated hydroxyanisole, a free radical scavenger, attenuated the ozone-induced increases in IL-6 expression in IL-1α-pretreated conjunctival epithelial cells. Therefore, we conclude that exposure to ozone exacerbates the detrimental effects on the integrity of the ocular

  10. Effects of Exposure to Ozone on the Ocular Surface in an Experimental Model of Allergic Conjunctivitis.

    PubMed

    Lee, Hun; Kim, Eung Kweon; Kim, Hee Young; Kim, Tae-Im

    2017-01-01

    Based on previous findings that ozone can induce an inflammatory response in the ocular surface of an animal model and in cultured human conjunctival epithelial cells, we investigated whether exposure to ozone exacerbates symptoms of allergic conjunctivitis. We evaluated the effects of exposure to ozone on conjunctival chemosis, conjunctival injection, corneal and conjunctival fluorescein staining scores, production of inflammatory cytokines in tears, and aqueous tear production in a mouse model of allergic conjunctivitis. To validate our in vivo results, we used interleukin (IL)-1α-pretreated conjunctival epithelial cells as an in vitro substitute for the mouse model. We evaluated whether exposure to ozone increased the inflammatory response and altered oxidative status and mitochondrial function in IL-1α-pretreated conjunctival epithelial cells. In the in vivo study, ozone induced increases in conjunctival chemosis, conjunctival injection, corneal and conjunctival fluorescein staining scores, and production of inflammatory cytokines, accompanied by a decrease in tear volume. In the in vitro study, exposure to ozone led to additional increases in IL-6 and tumor necrosis factor-α mRNA levels, which were already induced by treatment with IL-1α. Ozone did not induce any changes in cell viability. Pretreatment with IL-1α increased the expression of manganese superoxide dismutase, and exposure to ozone led to additional increments in the expression of this antioxidant enzyme. Ozone did not induce any changes in mitochondrial activity or expression of mitochondrial enzymes and proteins related to mitochondrial function, with the exception of phosphor-mammalian target of rapamycin. Treatment with butylated hydroxyanisole, a free radical scavenger, attenuated the ozone-induced increases in IL-6 expression in IL-1α-pretreated conjunctival epithelial cells. Therefore, we conclude that exposure to ozone exacerbates the detrimental effects on the integrity of the ocular

  11. Experimental and Modeling Studies of Massif Anorthosites

    NASA Technical Reports Server (NTRS)

    Longhi, John

    1999-01-01

    This termination report covers the latter part of a single research effort spanning several grant cycles. During this time there was a single title, "Experimental and Modeling Studies of Massif Anorthosites", but there were several contract numbers as the mode and location of NASA contract administration changed. Initially, the project was funded as an increment to the PI's other grant, "Early Differentiation of the Moon: Experimental and Modeling Studies", but subsequently it became an independent grant. Table 1 contains a brief summary of the dates and contract numbers.

  12. Experimental and computational studies of dynamic stall

    NASA Technical Reports Server (NTRS)

    Carr, L. W.; Platzer, M. F.; Chandrasekhara, M. S.; Ekaterinaris, J.

    1989-01-01

    A review of dynamic stall research in progress under the Navy-NASA Joint Institute of Aeronautics is presented. This effort, which includes both experimental and computational studies of the dynamic stall process, is directed toward better understanding and modeling of the fluid flow that occurs on helicopters and aircraft flying in conditions that induce dynamic stall. The results of research now in progress are presented, with discussion of the experimental program on compressibility effects on dynamic stall, related CFD studies of the stall process based on Navier-Stokes modeling, and viscous-inviscid flow modeling of the incipient stall process.

  13. DISTRIBUTIONS, ASSOCIATIONS, AND PARTIAL AGGREGATE EXPOSURE OF PESTICIDES AND POLYNUCLEAR AROMATIC HYDROCARBONS IN THE MINNESOTA CHILDREN'S PESTICIDE EXPOSURE STUDY (MNCPES)

    EPA Science Inventory

    The Minnesota Children's Pesticide Exposure Study (MNCPES) provides exposure, environmental, and biologic data relating to multi-pathway exposures of children for four primary pesticides (chlorpyrifos, malathion, diazinon, and atrazine), 14 secondary pesticides, and 13 polynucl...

  14. DISTRIBUTIONS, ASSOCIATIONS, AND PARTIAL AGGREGATE EXPOSURE OF PESTICIDES AND POLYNUCLEAR AROMATIC HYDROCARBONS IN THE MINNESOTA CHILDREN'S PESTICIDE EXPOSURE STUDY (MNCPES)

    EPA Science Inventory

    The Minnesota Children's Pesticide Exposure Study (MNCPES) provides exposure, environmental, and biologic data relating to multi-pathway exposures of children for four primary pesticides (chlorpyrifos, malathion, diazinon, and atrazine), 14 secondary pesticides, and 13 polynucl...

  15. Epizootic pneumonia of bighorn sheep following experimental exposure to Mycoplasma ovipneumoniae.

    PubMed

    Besser, Thomas E; Cassirer, E Frances; Potter, Kathleen A; Lahmers, Kevin; Oaks, J Lindsay; Shanthalingam, Sudarvili; Srikumaran, Subramaniam; Foreyt, William J

    2014-01-01

    Bronchopneumonia is a population limiting disease of bighorn sheep (Ovis canadensis). The cause of this disease has been a subject of debate. Leukotoxin expressing Mannheimia haemolytica and Bibersteinia trehalosi produce acute pneumonia after experimental challenge but are infrequently isolated from animals in natural outbreaks. Mycoplasma ovipneumoniae, epidemiologically implicated in naturally occurring outbreaks, has received little experimental evaluation as a primary agent of bighorn sheep pneumonia. In two experiments, bighorn sheep housed in multiple pens 7.6 to 12 m apart were exposed to M. ovipneumoniae by introduction of a single infected or challenged animal to a single pen. Respiratory disease was monitored by observation of clinical signs and confirmed by necropsy. Bacterial involvement in the pneumonic lungs was evaluated by conventional aerobic bacteriology and by culture-independent methods. In both experiments the challenge strain of M. ovipneumoniae was transmitted to all animals both within and between pens and all infected bighorn sheep developed bronchopneumonia. In six bighorn sheep in which the disease was allowed to run its course, three died with bronchopneumonia 34, 65, and 109 days after M. ovipneumoniae introduction. Diverse bacterial populations, predominantly including multiple obligate anaerobic species, were present in pneumonic lung tissues at necropsy. Exposure to a single M. ovipneumoniae infected animal resulted in transmission of infection to all bighorn sheep both within the pen and in adjacent pens, and all infected sheep developed bronchopneumonia. The epidemiologic, pathologic and microbiologic findings in these experimental animals resembled those seen in naturally occurring pneumonia outbreaks in free ranging bighorn sheep.

  16. Experimental Studies on Biosensing by SPR

    NASA Astrophysics Data System (ADS)

    Sun, Xiaochun; Shiokawa, Showko; Matsui, Yosikazu

    1989-09-01

    Biosensing using surface plasmon resonance is experimentally studied. The results obtained by detecting the bioresponse of the α-Feto protein system and cyclic experiments show that this technique has potential application in the field of biosensing. The effects of an organic layer on detecting sensitivity and restoration of sensors are also discussed.

  17. Experimental Approaches to Studying Biological Electron Transfer.

    ERIC Educational Resources Information Center

    Scott, Robert A.; And Others

    1985-01-01

    Provides an overview on biological electron-transfer reactions, summarizing what is known about how distance, spatial organization, medium, and other factors affect electron transfer. Experimental approaches, including studies of bimolecular electron transfer reactions (electrostatic effects and precursor complexes), are considered. (JN)

  18. EBTS:DESIGN AND EXPERIMENTAL STUDY.

    SciTech Connect

    PIKIN,A.; ALESSI,J.; BEEBE,E.; KPONOU,A.; PRELEC,K.; KUZNETSOV,G.; TIUNOV,M.

    2000-11-06

    Experimental study of the BNL Electron Beam Test Stand (EBTS), which is a prototype of the Relativistic Heavy Ion Collider (RHIC) Electron Beam Ion Source (EBIS), is currently underway. The basic physics and engineering aspects of a high current EBIS implemented in EBTS are outlined and construction of its main systems is presented. Efficient transmission of a 10 A electron beam through the ion trap has been achieved. Experimental results on generation of multiply charged ions with both continuous gas and external ion injection confirm stable operation of the ion trap.

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

    PubMed

    Xu, Jin; Bigelow, Timothy A

    2011-11-01

    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. Copyright © 2011 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  20. STUDIES OF PRESCHOOL CHILDREN'S EXPOSURES TO PESTICIDES

    EPA Science Inventory

    Young children, especially those of the preschool ages, are hypothesized to have greater exposures than do older children or adults to persistent organic pesticides and other persistent organic pollutants, including some compounds that may have endocrine-disrupting effects or d...

  1. STUDIES OF PRESCHOOL CHILDREN'S EXPOSURES TO PESTICIDES

    EPA Science Inventory

    Young children, especially those of the preschool ages, are hypothesized to have greater exposures than do older children or adults to persistent organic pesticides and other persistent organic pollutants, including some compounds that may have endocrine-disrupting effects or d...

  2. Temperature, hydric environment, and prior pathogen exposure alter the experimental severity of chytridiomycosis in boreal toads

    USGS Publications Warehouse

    Murphy, Peter J.; St-Hilaire, Sophie; Corn, Paul Stephen

    2011-01-01

    Prevalence of the pathogen Batrachochytrium dendrobatidis (Bd), implicated in amphibian population declines worldwide, is associated with habitat moisture and temperature, but few studies have varied these factors and measured the response to infection in amphibian hosts. We evaluated how varying humidity, contact with water, and temperature affected the manifestation of chytridiomycosis in boreal toads Anaxyrus (Bufo) boreas boreas and how prior exposure to Bd affects the likelihood of survival after re-exposure, such as may occur seasonally in long-lived species. Humidity did not affect survival or the degree of Bd infection, but a longer time in contact with water increased the likelihood of mortality. After exposure to ~106 Bd zoospores, all toads in continuous contact with water died within 30 d. Moreover, Bd-exposed toads that were disease-free after 64 d under dry conditions, developed lethal chytridiomycosis within 70 d of transfer to wet conditions. Toads in unheated aquaria (mean = 15°C) survived less than 48 d, while those in moderately heated aquaria (mean = 18°C) survived 115 d post-exposure and exhibited behavioral fever, selecting warmer sites across a temperature gradient. We also found benefits of prior Bd infection: previously exposed toads survived 3 times longer than Bd-naïve toads after re-exposure to 106 zoospores (89 vs. 30 d), but only when dry microenvironments were available. This study illustrates how the outcome of Bd infection in boreal toads is environmentally dependent: when continuously wet, high reinfection rates may overwhelm defenses, but periodic drying, moderate warming, and previous infection may allow infected toads to extend their survival.

  3. Experimental and numerical modeling of chloride diffusivity in hardened cement concrete considering the aggregate shapes and exposure-duration effects

    NASA Astrophysics Data System (ADS)

    Jie, Wu; Dassekpo, Jean-Baptiste Mawulé; Wan, Chengyong; Zha, Xiaoxiong

    This paper presents an experimental and numerical model describing the effects of the aggregate shapes and exposure duration of chloride diffusion into cement-based materials. A simple chloride diffusion test was performed on a concrete specimen composed of a mixture of cement mortar with crushed granites and round gravels. A simulation was done and the numerical model developed was applied to the matrix at the meso-scale level and the chloride diffusivity was investigated at 30, 60, and 90 days. The experimental and simulation results showed that the aggregate shape and the exposure duration of chloride diffusing into concrete are of high significance. It was indicated that the model with crushed granite presents a good resistance against chloride ingress, while the model with rounded gravels shows some sensitivity to the chloride penetration. It was also found out that when the time dependence of the diffusion coefficient is not taken into account, the diffusion rate will be overestimated. The meso-scale model developed in this study also provides a new method applied in the analysis of the chloride and water transport that causes damage to concrete considering the particle inclusion and the diffusion duration.

  4. The Effect of Exposure to Pro-Tobacco Advertising on Experimentation With Emerging Tobacco Products Among U.S. Adolescents.

    PubMed

    Agaku, Israel T; Ayo-Yusuf, Olalekan A

    2014-06-01

    This study assessed the influence of exposure to pro-tobacco advertisements on experimentation with emerging tobacco products among U.S. adolescents aged ≥9 years, in Grades 6 to 12. Data were obtained from the 2011 National Youth Tobacco Survey. Multivariate logistic regression was used to measure the association between experimentation with snus and e-cigarettes and exposure to pro-tobacco advertisements from three sources: over the Internet, in newspapers/magazines, and at retail stores. After controlling for sociodemographic characteristics and current use of other tobacco products, the odds of experimenting with snus were 1.36 (95% confidence interval [CI] = 0.88-3.16), 2.03 (95% CI = 1.30-3.17), and 3.24 (95% CI = 2.07-5.07), among students exposed to one, two, or all three types of pro-tobacco advertisements, respectively, compared with those exposed to none. Similar results were obtained for e-cigarettes. Stronger restrictions on tobacco advertisements, in concert with increased tobacco taxes and warning about the dangers of tobacco, use may help reduce youth tobacco use. © 2013 Society for Public Health Education.

  5. Trend tests for the evaluation of exposure-response relationships in epidemiological exposure studies

    PubMed Central

    Hothorn, Ludwig A; Vaeth, Michael; Hothorn, Torsten

    2009-01-01

    One possibility for the statistical evaluation of trends in epidemiological exposure studies is the use of a trend test for data organized in a 2 × k contingency table. Commonly, the exposure data are naturally grouped or continuous exposure data are appropriately categorized. The trend test should be sensitive to any shape of the exposure-response relationship. Commonly, a global trend test only determines whether there is a trend or not. Once a trend is seen it is important to identify the likely shape of the exposure-response relationship. This paper introduces a best contrast approach and an alternative approach based on order-restricted information criteria for the model selection of a particular exposure-response relationship. For the simple change point alternative H1 : π1 = ...= πq <πq+1 = ... = πk an appropriate approach for the identification of a global trend as well as for the most likely shape of that exposure-response relationship is characterized by simulation and demonstrated for real data examples. Power and simultaneous confidence intervals can be estimated as well. If the conditions are fulfilled to transform the exposure-response data into a 2 × k table, a simple approach for identification of a global trend and its elementary shape is available for epidemiologists. PMID:19265556

  6. Experimental asbestos studies in the UK: 1912-1950.

    PubMed

    Greenberg, Morris

    2017-11-01

    The asbestos industry originated in the UK in the 1870s. By 1898, asbestos had many applications and was reported to be one of the four leading causes of severe occupational disease. In 1912, the UK government sponsored an experimental study that reported that exposure to asbestos produced no more than a modicum of pulmonary fibrosis in guinea pigs. In the 1930s, the newly established Medical Research Council, with assistance from industry, sponsored a study of the effects of exposing animals to asbestos by injection (intratracheal and subcutaneous) and by inhalation in the factory environment. Government reports, publications, and contemporary records obtained by legal discovery have been reviewed in the context of the stage of scientific development and the history of the times. Experimenters were engaged in a learning process during the 1912-1950 period, and their reports of the effects of asbestos were inconsistent. Pathologists who studied the effects of asbestos experimentally, at whole animal, tissue and cellular levels, advanced experimental methodology and mechanistic knowledge. In the hands of public relations experts, however, research was exploited to preserve an industry and perpetuate preventable diseases, a practice that continues to this day. © 2017 Wiley Periodicals, Inc.

  7. Effects of dietary lead exposure on vitamin levels in great tit nestlings - An experimental manipulation.

    PubMed

    Ruiz, Sandra; Espín, Silvia; Rainio, Miia; Ruuskanen, Suvi; Salminen, Juha-Pekka; Lilley, Thomas M; Eeva, Tapio

    2016-06-01

    Exposure to metal pollution negatively affects animal physiology, including nutrient metabolism, but in the wild an effect can seldom be attributed to a single metal. Moreover, little is known about how the metabolism of vitamins, essential micronutrients for developing juveniles, is affected by toxic metals. Therefore we experimentally investigated the effects of lead (Pb), a widespread toxic metal, on four fat-soluble vitamins A (total and retinol), D3, E (total and α-tocopherol) and K and carotenoids (lutein, zeaxanthin and unidentified) in great tit (Parus major) nestlings. In addition to a control group where no Pb was provided, two Pb-dosed groups were compared to a metal exposed group in the vicinity of a Ni-Cu smelter. We examined whether Pb treatment affects vitamin homeostasis and how the response of Pb-treated birds relates to that of a population under industrial exposure of Pb and other metals. For this purpose, vitamin and carotenoid levels were quantified with UPLC-MS from plasma of 7 days-old nestlings. All metal exposed groups showed increased vitamin A and retinol levels. However, vitamin levels were not directly associated with fecal Pb levels, with the exception of retinol, which was positively correlated with fecal Pb. Alpha-tocopherol, lutein and zeaxanthin levels were positively associated with body mass and wing growth rate. To conclude, Pb exposure increased plasma vitamin A and retinol levels while the levels of other vitamins and carotenoids rather reflected secondary pollution effects via differences in habitat and diet quality at the smelter site. Our findings suggest Pb exposed nestlings may allocate the vitamins needed for growth and development to fight the physiological stress thus compromising their fitness.

  8. Experimental infection of rabbits with bovine viral diarrhoea virus by a natural route of exposure

    PubMed Central

    2014-01-01

    Bovine viral diarrhoea virus (BVDV) is an important pathogen of cattle that can naturally infect a wide range of even-toed ungulates. Non-bovine hosts may represent reservoirs for the virus that have the potential to hamper BVDV eradication programs usually focused on cattle. Rabbits are very abundant in countries such as the United Kingdom or Australia and are often living on or near livestock pastures. Earlier reports indicated that rabbits can propagate BVDV upon intravenous exposure and that natural infection of rabbits with BVDV may occur but experimental proof of infection of rabbits by a natural route is lacking. Therefore, New Zealand White rabbits were exposed to a Scottish BVDV field strain intravenously, oro-nasally and by contaminating their hay with virus. None of the animals showed any clinical signs. However, the lymphoid organs from animals sacrificed at day five after exposure showed histological changes typical of transient infection with pestivirus. Most organ samples and some buffy coat samples were virus positive at day five but saliva samples remained negative. Development of antibodies was observed in all intravenously challenged animals, in all of the nebulised group and in four of six animals exposed to contaminated hay. To our knowledge this is the first report of BVDV propagation in a species other than ruminants or pigs after exposure to the virus by a natural route. However, to assess the role of rabbits as a potential reservoir for BVDV it remains to be determined whether persistent infection caused by intra-uterine infection is possible and whether BVDV is circulating in wild rabbit populations. PMID:24690167

  9. Experimental Optimization of Exposure Index and Quality of Service in Wlan Networks.

    PubMed

    Plets, David; Vermeeren, Günter; Poorter, Eli De; Moerman, Ingrid; Goudos, Sotirios K; Luc, Martens; Wout, Joseph

    2017-07-01

    This paper presents the first real-life optimization of the Exposure Index (EI). A genetic optimization algorithm is developed and applied to three real-life Wireless Local Area Network scenarios in an experimental testbed. The optimization accounts for downlink, uplink and uplink of other users, for realistic duty cycles, and ensures a sufficient Quality of Service to all users. EI reductions up to 97.5% compared to a reference configuration can be achieved in a downlink-only scenario, in combination with an improved Quality of Service. Due to the dominance of uplink exposure and the lack of WiFi power control, no optimizations are possible in scenarios that also consider uplink traffic. However, future deployments that do implement WiFi power control can be successfully optimized, with EI reductions up to 86% compared to a reference configuration and an EI that is 278 times lower than optimized configurations under the absence of power control. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. Experimental validation of a statistical model for evaluating the past or future magnetic field exposures of a population living near power lines.

    PubMed

    Turgeon, Alain; Bourdages, Michel; Levallois, Patrick; Gauvin, Denis; Gingras, Suzanne; Deadman, Jan Erik; Goulet, Daniel L; Plante, Michel

    2004-07-01

    This study was designed to provide an experimental validation for a statistical model predicting past or future exposures to magnetic fields (MF) from power lines. The model estimates exposure, combining the distribution of ambient MF in the absence of power lines with the distribution of past or future MF produced by power lines. In the study, validation is carried out by comparing exposures predicted by the model with the actual measurements obtained from a large-scale epidemiological study. The comparison was made for a group of 220 women living near a 735 kV power line. Knowing that the individual arithmetic means of MF exposures follow a log-normal distribution, the Pearson correlation between the log-transformed measured means and the calculated ones was determined and found to be 0.77. Predicted values of MF exposures were slightly lower than measured values. The calculated geometric mean of the group was 0.33 microT, compared to 0.38 microT for the measured geometric mean. The present study shows good agreement between the measured MF exposure of an individual inside a house near a 735 kV line and the MF exposure calculated using a statistical model.

  11. A case-control study of occupational sunlight exposure and renal cancer risk.

    PubMed

    Karami, Sara; Colt, Joanne S; Stewart, Patricia A; Schwartz, Kendra; Davis, Faith G; Ruterbusch, Julie J; Chow, Wong-Ho; Wacholder, Sholom; Graubard, Barry I; Purdue, Mark P; Moore, Lee E

    2016-04-01

    Epidemiological evidence of a relationship between vitamin D and kidney cancer risk has been inconsistent despite experimental data indicating that vitamin D and its metabolites may inhibit carcinogenesis. Previously we reported an inverse association between renal cell carcinoma (RCC) risk and occupational ultraviolet (UV) exposure among European men. In this study, we examined the association between occupational UV exposure and RCC risk among US residents and investigated whether this association varied by race and sex. Lifetime occupational data for 1,217 RCC cases and 1,235 controls in a population-based case-control study, conducted from 2002 to 2007, were assessed for occupational UV exposure. We evaluated exposure metrics in quartiles based on control exposure levels and calculated associations between RCC risk and occupational UV exposure using unconditional logistic regression adjusted for sex, race, body mass index, smoking, hypertension, center, education, family history of cancer and dietary vitamin D intake. A general pattern of decreasing RCC risk with increasing UV exposure was observed. Cases had significantly lower cumulative occupational UV exposure than controls (fourth quartile vs. first: odds ratio = 0.74 [95% confidence interval = 0.56-0.99], p-trend = 0.03). Similar results were observed for other UV exposure metrics. The association with occupational UV exposure was stronger for women than for men, but did not differ by race. Our findings suggest an inverse association between occupational UV exposure and RCC, particularly among women. Given the sex finding discrepancies in this study versus our previous study, additional research is need to clarify whether the protective effects of occupational UV exposure and RCC risk are real. © 2015 UICC.

  12. Experimental and computational study of thaumasite structure

    SciTech Connect

    Scholtzová, Eva; Kucková, Lenka; Kožíšek, Jozef; Pálková, Helena; Tunega, Daniel

    2014-05-01

    The structure of thaumasite has been studied experimentally by means of a single crystal X-ray diffraction and FTIR methods, and theoretically using density functional theory (DFT) method. Very good agreement was achieved between calculated and experimental structural parameters. In addition, calculations offered the refinement of the positions of the hydrogen atoms. The detailed analysis of the hydrogen bonds existing in the thaumasite structure has been performed. Several types of hydrogen bonds have been classified. The water molecules coordinating Ca{sup 2+} cation act as proton donors in moderate O-H···O hydrogen bonds formed with CO₃⁻²and SO₄⁻² anions. The multiple O-H···O hydrogen bonds exist among water molecules themselves. Finally, relatively weak hydrogen bonds form water molecules with the OH groups from the coordination sphere of the Si(OH)₆⁻² anion. Further, calculated vibrational spectrum allowed complete assignment of all vibrational modes which are not available from the experimental spectrum that has a complex structure with overlapped bands, especially below 1500 cm⁻¹. Highlights: • The thaumasite structure was studied experimentally and using DFT method. • We used DFT method for the refinement of the positions of hydrogen atoms. • A detailed analysis of the hydrogen bonds was done. • A complete assignment of all bands to particular types of vibrations was done.

  13. Experimental Study of the Current Filamentation Instability

    NASA Astrophysics Data System (ADS)

    Allen, Brian; Muggli, Patric; Silva, Luis O.; Martins, Joana; Yakimenko, Vitaly; Fedurin, Mikhail; Kusche, Karl; Babzien, Marcus; Huang, Chengkun; Mori, Warren

    2012-10-01

    The Current Filamentation Instability (CFI) is of central importance for the propagation of relativistic electron beams in plasmas. CFI has potential relevance to astrophysics, afterglow of gamma ray bursts, inertial confinement fusion, energy transport in the fast-igniter concept, and places an upper limit on the plasma density and accelerating gradient in PWFA's. An experimental study at the Accelerator Test Facility at Brookhaven National Laboratory with the 60MeV e^- beam and cm length plasma. The experiment included the systematic study and characterization of the instability as a function of the beam charge and plasma density. The transverse beam profile is measured directly at the plasma exit using OTR. Experimental results show the transition from plasma focusing to CFI near kpσr=1 characterized by the appearance of multiple (1-5) beam filaments and scaling of the transverse filament size with the plasma skin depth. Suppression of the instability is seen by lowering the growth rate of the instability by reducing the beam charge. The experimental results are in excellent agreement with theory and simulations and we present and discuss simulation and experimental results.

  14. An Experimental Basis for the Estimation of Auditory System Hazard Following Exposure to Impulse Noise

    DTIC Science & Technology

    1992-02-01

    Impulse Noise (Reprint) DTIC By SElEC.’E APR 21 1992 James H. Patterson, Jr. D Sensory Research Division and Roger P. Hamernik Auditory Research Laboratory...FRMA LTC, MS Director, Sens y Research Released for publication: ReV W. ,.DPh.D. DVDH E Chairman, Scientif-ic- Colonel, MC, FS Review Committee...more than the conventional A-weighting function. In the second study, the exposures consisted of 20. DISTRIBUTION/AVAILABILITY OF ABSTRACT 21 . ABSTRACT

  15. Exposure measurement error in PM2.5 health effects studies: A pooled analysis of eight personal exposure validation studies

    PubMed Central

    2014-01-01

    Background Exposure measurement error is a concern in long-term PM2.5 health studies using ambient concentrations as exposures. We assessed error magnitude by estimating calibration coefficients as the association between personal PM2.5 exposures from validation studies and typically available surrogate exposures. Methods Daily personal and ambient PM2.5, and when available sulfate, measurements were compiled from nine cities, over 2 to 12 days. True exposure was defined as personal exposure to PM2.5 of ambient origin. Since PM2.5 of ambient origin could only be determined for five cities, personal exposure to total PM2.5 was also considered. Surrogate exposures were estimated as ambient PM2.5 at the nearest monitor or predicted outside subjects’ homes. We estimated calibration coefficients by regressing true on surrogate exposures in random effects models. Results When monthly-averaged personal PM2.5 of ambient origin was used as the true exposure, calibration coefficients equaled 0.31 (95% CI:0.14, 0.47) for nearest monitor and 0.54 (95% CI:0.42, 0.65) for outdoor home predictions. Between-city heterogeneity was not found for outdoor home PM2.5 for either true exposure. Heterogeneity was significant for nearest monitor PM2.5, for both true exposures, but not after adjusting for city-average motor vehicle number for total personal PM2.5. Conclusions Calibration coefficients were <1, consistent with previously reported chronic health risks using nearest monitor exposures being under-estimated when ambient concentrations are the exposure of interest. Calibration coefficients were closer to 1 for outdoor home predictions, likely reflecting less spatial error. Further research is needed to determine how our findings can be incorporated in future health studies. PMID:24410940

  16. A Crew Exposure Study. Volume 1. Offshore

    DTIC Science & Technology

    1984-06-01

    level contour I maps were generated for seven platforms and two rigs. Personal noise dosimetry data ’ were collected during drilling and tripping...limits. Noise dosimetry data were interpreted relative to the exposure guidelines in USCG Navigation and Vessel Inspection Circular (NVC 12-82). The... dosimetry data. Finally, this report could not have been pro- duced without the skill and patience of Mrs. Dorothy Endicott who typed the report

  17. Virtual reality exposure and imaginal exposure in the treatment of fear of flying: a pilot study.

    PubMed

    Rus-Calafell, Mar; Gutiérrez-Maldonado, José; Botella, Cristina; Baños, Rosa M

    2013-07-01

    Fear of flying (FF) is an impairing psychological disorder that is extremely common in developed countries. The most effective treatment for this particular type of phobia is exposure therapy. However, there are few studies comparing imaginal exposure (IE) and virtual reality (VR) exposure for the treatment of FF. The present study compared the effectiveness of these two approaches using two manualized interventions based on the exposure technique. Patients with FF (N = 15) were randomly assigned to either VR (n = 7) or IE therapy (n = 8), consisting of a total of eight sessions: two assessment sessions (pre-treatment and after the real flight) and six exposure therapy sessions, which were conducted twice a week. During each exposure session, subjective perceived anxiety was measured every 5 min. Participants were also asked to sit through a real flight immediately after the treatment. The results showed no differences between the two treatments in relation to reduced clinical symptomatology associated with the FF, although participants in the VR group experienced less anxiety during the real flight after treatment. Furthermore, at 6-month follow-up, danger expectations and flight anxiety continued to decrease in participants who had received the VR exposure therapy, and four of these seven participants took at least one more flight.

  18. Recruitment and Retention Strategies for Environmental Exposure Studies: Lessons from the Detroit Exposure and Aerosol Research Study

    EPA Science Inventory

    The Environmental Protection Agency’s Detroit Exposure and Aerosol Research Study (DEARS) was a complex 3-year personal exposure study. The six geographically defined areas in the Detroit (Wayne County), Michigan, area used as study locations are ethnically diverse; the majority ...

  19. Recruitment and Retention Strategies for Environmental Exposure Studies: Lessons from the Detroit Exposure and Aerosol Research Study

    EPA Science Inventory

    The Environmental Protection Agency’s Detroit Exposure and Aerosol Research Study (DEARS) was a complex 3-year personal exposure study. The six geographically defined areas in the Detroit (Wayne County), Michigan, area used as study locations are ethnically diverse; the majority ...

  20. A case-control study of occupational sunlight exposure and renal cancer risk

    PubMed Central

    Karami, Sara; Colt, Joanne S.; Stewart, Patricia A.; Schwartz, Kendra; Davis, Faith G.; Ruterbusch, Julie J.; Chow, Wong-Ho; Wacholder, Sholom; Graubard, Barry I.; Purdue, Mark P.; Moore, Lee E.

    2015-01-01

    Epidemiological evidence of a relationship between vitamin D and kidney cancer risk has been inconsistent despite experimental data indicating that vitamin D and its metabolites may inhibit carcinogenesis. Previously we reported an inverse association between renal cell carcinoma (RCC) risk and occupational ultraviolet (UV) exposure among European men. In the current study, we examined the association between occupational UV exposure and RCC risk among US residents and investigated whether this association varied by race and sex. Lifetime occupational data for 1,217 RCC cases and 1,235 controls in a population-based case-control study, conducted from 2002-2007, were assessed for occupational UV exposure. We evaluated exposure metrics in quartiles based on control exposure levels and calculated associations between RCC risk and occupational UV exposure using unconditional logistic regression adjusted for sex, race, body mass index, smoking, hypertension, center, education, family history of cancer, and dietary vitamin D intake. A general pattern of decreasing RCC risk with increasing UV exposure was observed. Cases had significantly lower cumulative occupational UV exposure than controls (fourth quartile vs. first: odds ratio=0.74 [95% confidence interval=0.56-0.99], P-trend=0.03). Similar results were observed for other UV exposure metrics. The association with occupational UV exposure was stronger for women than men, but did not differ by race. Our findings suggest an inverse association between occupational UV exposure and RCC, particularly among women. Given the sex finding discrepancies in our current versus previous study, additional research is need to clarify whether the protective effects of occupational UV exposure and RCC risk are real. PMID:26505275

  1. RECRUITMENT STRATEGIES FOR AN EXPOSURE MEASUREMENT STUDY OF PRESCHOOL CHILDREN

    EPA Science Inventory

    Recruiting study participants is always a challenge for researchers. It poses an even bigger challenge for researchers to recruit participants for a study involving intrusive, burdensome data collection activities. A study of preschool children's exposure to persistent organic ...

  2. RECRUITMENT STRATEGIES FOR AN EXPOSURE MEASUREMENT STUDY OF PRESCHOOL CHILDREN

    EPA Science Inventory

    Recruiting study participants is always a challenge for researchers. It poses an even bigger challenge for researchers to recruit participants for a study involving intrusive, burdensome data collection activities. A study of preschool children's exposure to persistent organic ...

  3. Experimental studies on waste paper pulp biodegradation.

    PubMed

    Sharma, R; Sharma, D; Rao, K S; Jain, R C

    2002-07-01

    In continuation of their studies on Biodegradation of cellulosic waste materials, the authors have presented their experimental data on biodegradation on waste paper pulp. Greater efficiency in the cow dung and M3 culture experimental setups have been pointed out and discussed. Necessity of detailed data evaluation of temperature, pH, dry weight, cellulose, protein, carbohydrate, Nitrate, Phosphate & Potassium levels is suggested. Derivation of %, absolute and increase/decrease % of BOO, COD and VS have been pointed out for the first time in solid waste Biodegradation. Further data evaluation and derivation of critical reaction rate kinetics have been recommended for further studies in solid waste-degradation to achieve quicker Bioconversion of cellulosic wastes into compost.

  4. Early Programming of Uterine Tissue by Bisphenol A: Critical Evaluation of Evidence from Animal Exposure Studies

    PubMed Central

    Suvorov, Alexander; Waxman, David J.

    2015-01-01

    Exposure to Bisphenol A (BPA) during the critical window of uterine development has been proposed to program the uterus for increased disease susceptibility based on well-documented effects of the potent xenoestrogen diethylstilbestrol. To investigate this proposal, we reviewed 37 studies of prenatal and/or perinatal BPA exposure in animal models and evaluated evidence for: molecular signatures of early BPA exposure; the development of adverse uterine health effects; and epigenetic changes linked to long-term dysregulation of uterine gene expression and health effects. We found substantial evidence for adult uterine effects of early BPA exposure. In contrast, experimental support for epigenetic actions of early BPA exposure is very limited, and largely consists of effects on Hoxa gene DNA methylation. Critical knowledge gaps were identified, including the need to fully characterize short-term and long-term uterine gene responses, interactions with estrogens and other endogenous hormones, and any long-lasting epigenetic signatures that impact adult disease. PMID:26028543

  5. Investing in Prospective Cohorts for Etiologic Study of Occupational Exposures

    PubMed Central

    Blair, A.; Hines, C.J.; Thomas, K.W.; Alavanja, M.C.R.; Beane Freeman, L.E.; Hoppin, J.A.; Kamel, F.; Lynch, C.F.; Lubin, J.H.; Silverman, D.T.; Whelan, E.; Zahm, S. H.; Sandler, D. P.

    2015-01-01

    Prospective cohorts have played a major role in understanding the contribution of diet, physical activity, medical conditions, and genes to the development of many diseases, but have not been widely used for occupational exposures. Studies in agriculture are an exception. We draw upon our experience using this design to study agricultural workers to identify conditions that might foster use of prospective cohorts to study other occupational settings. Prospective cohort studies are perceived by many as the strongest epidemiologic design. It allows updating of information on exposure and other factors, collection of biologic samples before disease diagnosis for biomarker studies, assessment of effect modification by genes, lifestyle, and other occupational exposures, and evaluation of a wide range of health outcomes. Increased use of prospective cohorts would be beneficial in identifying hazardous exposures in the workplace. Occupational epidemiologists should seek opportunities to initiate prospective cohorts to investigate high priority, occupational exposures. PMID:25603935

  6. Theoretical and Experimental Study of Thermoacoustic Engines

    DTIC Science & Technology

    1992-12-01

    61153N11 uri5005 11. TITLE (Include Security Classification) Theoretical and Experimental Study of Thermoacoustic Engines 12 . PERSONAL AUTHOR(S) Richard...9/30 92/ 12 /31 16. SUPPLEMENTARY NOTATION 17. COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIELD...central portion. Copper rings of thickness 3.2 mm, inner radius 4.32 cm, and outer radius of 12 cm were supported between the ends of the ceramic piece

  7. Theoretical and experimental studies of elementary particles

    NASA Astrophysics Data System (ADS)

    Bodek, A.; Ferbel, T.; Melissinos, A. C.; Olsen, S. L.; Slattery, P.; Tipton, P.; Das, A.; Hagen, C. R.; Rajeev, S. G.; Okubo, S.

    This report discusses fixed target experimentation at Fermilab; the D-zero collider experiment at Fermilab; deep inelastic lepton nucleon scattering; non-accelerator experiments and non-linear quantum electrodynamics (QED); the AMY experiment at TRISTAN and other activities at KEK; the collider detector at Fermilab; laser switched linac; preparations for experiments at the SSC; search for massive stable particles; and the Advanced Study Institute on techniques and concepts of high energy physics.

  8. Experimental Investigation of Microbially Induced Corrosion of Test Samples and Effect of Self-Assembled Hydrophobic Monolayers. Exposure of Test Samples to Continuous Microbial Cultures, Chemical Analysis, and Biochemical Studies

    SciTech Connect

    Laurinavichius, K.S.

    1998-09-30

    The study of biocorrosion of aluminum and beryllium samples were performed under conditions of continuous fermentation of thermophilic anaerobic microorganisms of different groups. This allowed us to examine the effect of various types of metabolic reactions of reduction-oxidation proceeding at different pH and temperatures under highly reduced conditions on aluminum and beryllium corrosion and effect of self-assembled hydrophobic monolayers.

  9. Epizootic Pneumonia of Bighorn Sheep following Experimental Exposure to Mycoplasma ovipneumoniae

    PubMed Central

    Besser, Thomas E.; Cassirer, E. Frances; Potter, Kathleen A.; Lahmers, Kevin; Oaks, J. Lindsay; Shanthalingam, Sudarvili; Srikumaran, Subramaniam; Foreyt, William J.

    2014-01-01

    Background Bronchopneumonia is a population limiting disease of bighorn sheep (Ovis canadensis). The cause of this disease has been a subject of debate. Leukotoxin expressing Mannheimia haemolytica and Bibersteinia trehalosi produce acute pneumonia after experimental challenge but are infrequently isolated from animals in natural outbreaks. Mycoplasma ovipneumoniae, epidemiologically implicated in naturally occurring outbreaks, has received little experimental evaluation as a primary agent of bighorn sheep pneumonia. Methodology/Principal Findings In two experiments, bighorn sheep housed in multiple pens 7.6 to 12 m apart were exposed to M. ovipneumoniae by introduction of a single infected or challenged animal to a single pen. Respiratory disease was monitored by observation of clinical signs and confirmed by necropsy. Bacterial involvement in the pneumonic lungs was evaluated by conventional aerobic bacteriology and by culture-independent methods. In both experiments the challenge strain of M. ovipneumoniae was transmitted to all animals both within and between pens and all infected bighorn sheep developed bronchopneumonia. In six bighorn sheep in which the disease was allowed to run its course, three died with bronchopneumonia 34, 65, and 109 days after M. ovipneumoniae introduction. Diverse bacterial populations, predominantly including multiple obligate anaerobic species, were present in pneumonic lung tissues at necropsy. Conclusions/Significance Exposure to a single M. ovipneumoniae infected animal resulted in transmission of infection to all bighorn sheep both within the pen and in adjacent pens, and all infected sheep developed bronchopneumonia. The epidemiologic, pathologic and microbiologic findings in these experimental animals resembled those seen in naturally occurring pneumonia outbreaks in free ranging bighorn sheep. PMID:25302992

  10. A simulation study to quantify the impacts of exposure ...

    EPA Pesticide Factsheets

    A simulation study to quantify the impacts of exposure measurement error on air pollution health risk estimates in copollutant time-series models The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas. CED uses modeling-based approaches to characterize exposures, evaluate fate and transport, and support environmental diagnostics/forensics with input from multiple data sources. It also develops media- and receptor-specific models, process models, and decision support tools for use both within and outside of EPA.

  11. A simulation study to quantify the impacts of exposure ...

    EPA Pesticide Factsheets

    A simulation study to quantify the impacts of exposure measurement error on air pollution health risk estimates in copollutant time-series models The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas. CED uses modeling-based approaches to characterize exposures, evaluate fate and transport, and support environmental diagnostics/forensics with input from multiple data sources. It also develops media- and receptor-specific models, process models, and decision support tools for use both within and outside of EPA.

  12. The Australian Work Exposures Study: Occupational Exposure to Lead and Lead Compounds.

    PubMed

    Driscoll, Timothy R; Carey, Renee N; Peters, Susan; Glass, Deborah C; Benke, Geza; Reid, Alison; Fritschi, Lin

    2016-01-01

    The aims of this study were to produce a population-based estimate of the prevalence of work-related exposure to lead and its compounds, to identify the main circumstances of exposures, and to collect information on the use of workplace control measures designed to decrease those exposures. Data came from the Australian Workplace Exposures Study, a nationwide telephone survey which investigated the current prevalence and circumstances of work-related exposure to 38 known or suspected carcinogens, including lead, among Australian workers aged 18-65 years. Using the web-based tool, OccIDEAS, semi-quantitative information was collected about exposures in the current job held by the respondent. Questions were addressed primarily at tasks undertaken rather than about self-reported exposures. A total of 307 (6.1%) of the 4993 included respondents were identified as probably being exposed to lead in the course of their work. Of these, almost all (96%) were male; about half worked in trades and technician-related occupations, and about half worked in the construction industry. The main tasks associated with probable exposures were, in decreasing order: soldering; sanding and burning off paint while painting old houses, ships, or bridges; plumbing work; cleaning up or sifting through the remains of a fire; radiator-repair work; machining metals or alloys containing lead; mining; welding leaded steel; and working at or using indoor firing ranges. Where information on control measures was available, inconsistent use was reported. Applied to the Australian working population, approximately 6.3% [95% confidence interval (CI) = 5.6-7.0] of all workers (i.e. 631000, 95% CI 566000-704000 workers) were estimated to have probable occupational exposure to lead. Lead remains an important exposure in many different occupational circumstances in Australia and probably other developed countries. This information can be used to support decisions on priorities for intervention and control

  13. Environmental tobacco smoke: Exposure-response relationships in epidemiologic studies

    SciTech Connect

    Wu-Williams, A.H. ); Samet, J.M. )

    1990-01-01

    Demonstration of a dose-response relationship for environmental tobacco smoke (ETS) is an important indication of causality. Central to the analysis and interpretation of dose-response relations as described in epidemiological studies is the relationship between dose and exposure. It must be recognized that in studies of ETS the authors have only surrogate measures of dose, and these surrogate measures (based on exposure) are imperfect. The question-based measures of ETS exposure generally have not been standardized, may have limited validity and reliability, and cannot comprehensively describe total ETS exposure, exposure to individual ETS components, nor doses of biologically relevant agents at target sites. Nevertheless, useful data have been yielded in epidemiologic studies linking ETS exposure to increased respiratory infection and symptoms, reduced lung growth in children, and increased lung cancer in nonsmoking adults. The more consistent exposure-response data for studies on acute health in children may reflect the greater difficulty in measuring exposure in studies of chronic health in adults.

  14. Teens with heavy prenatal cocaine exposure respond to experimental social provocation with escape not aggression.

    PubMed

    Greenwald, M K; Chiodo, L M; Hannigan, J H; Sokol, R J; Janisse, J; Delaney-Black, V

    2011-01-01

    Preclinical data show that, compared to no exposure, prenatal cocaine exposure (PCE) has age-dependent effects on social interaction and aggression. The aim of this clinical study was to determine how heavy/persistent PCE--after controlling for other prenatal drug exposures, sex and postnatal factors--predicts behavioral sensitivity to provocation (i.e., reactive aggression) using a well-validated human laboratory model of aggression. African American teens (mean=14.2 years old) with histories of heavy/persistent PCE (maternal cocaine use ≥ 2 times/week during pregnancy, or positive maternal or infant urine/meconium test at delivery; n=86) or none/some exposure (NON: maternal cocaine use < 2 times/week during pregnancy; n=330) completed the Point Subtraction Aggression Paradigm. In this task, teens competed in a computer game against a fictitious opponent. There were three possible responses: (a) earn points, to exchange for money later; or (b) "aggress" against the fictitious opponent by subtracting their points; or (c) escape temporarily from point subtraction perpetrated by the fictitious opponent. The PCE group responded significantly more frequently on the escape option than the NON group, but did not differ in aggressive or money-earning responses. These data indicate that PCE-teens provoked with a social stressor exhibit a behavioral preference for escape (negative reinforcement) than for aggressive (retaliatory) or appetitive (point- or money-reinforced) responses. These findings are consistent with preclinical data showing that social provocation of adolescent or young adult offspring after PCE is associated with greater escape behavior, inferring greater submission, social withdrawal, or anxiety, as opposed to aggressive behavior.

  15. Experimental study of the chaotic waterwheel

    NASA Astrophysics Data System (ADS)

    Rutherford, George; Erxleben, Amy; Rosa, Epaminondas, Jr.

    2007-03-01

    The chaotic waterwheel is often given as an example of a mechanical system that can exhibit chaotic behavior. Its early demonstration by Malkus and the realization that it can be modeled by the Lorenz equations has secured it a prominent place in almost every general presentation of chaos. It seems quite surprising, then, that no experimental investigations of this textbook system have ever been published. To fill this historic gap, and to initiate an experimental study of this incredibly rich dynamic system, our lab has constructed a research-grade waterwheel consisting of a vacuum-formed polycarbonate frame in which 36 cylindrical cells are mounted on an 18 inch diameter. The wheel and its axis can be tilted, and water is fed into the top of the wheel and drains out through thin tubes at the bottom of each cell. An aluminum skirt at the wheel's periphery passes through a variable gap magnet to provide magnetic braking. Angular time series data are collected with an absolute rotary encoder. The data are smoothed and angular velocity and acceleration are calculated via fast fourier transforms. The data show quasi-uniform rotation as well as periodic and chaotic motion and agree fairly well with computer simulations of the idealized wheel equations. We will discuss differences between the experimental data and the simulation predictions as well as plans for future studies.

  16. Experimental study of double-cavity flow

    NASA Astrophysics Data System (ADS)

    Tuerke, F.; Pastur, L. R.; Sciamarella, D.; Lusseyran, F.; Artana, G.

    2017-07-01

    The flow through two facing, identical cavities (double-cavity) is characterized experimentally, as the inflow velocity and the distance between the cavities is varied. Standard 2D2C particle image velocimetry measurements in the spanwise mid-plane provide information on the instantaneous and mean velocity flow fields. Laser Doppler velocimetry measurements at several points in the double-cavity domain reveal the global character of the streamwise fluctuating velocity spectra. The flow is characterized based on time series, recorded in the shear layer of one of the cavities, for a wide range of inflow velocities and intercavity distances. In a detailed spectral study, we show how the shear layer spectra get affected when the two cavities are brought closer together. Based on the experimental data, a temporal local linear stability analysis was carried out, which was able to explain why the frequency peaks for close intercavity distances broaden and move to higher Strouhal numbers.

  17. Experimental studies of gravitation and feebler forces

    SciTech Connect

    Cowsik, R.

    1993-04-01

    The theoretical motivations and the experimental context pertaining to the recent experimental studies of the Weak equivalence Principle and the {open_quotes}Fifth Force{close_quotes} are reviewed briefly. With such a backdrop, the innovative design and the technical details of the several new experiments in this area are presented with a special emphasis on the experiments underway at Gauribidanur, situated on the Deccan Plateau. These experiments jointly rule out the existence of any new forces coupling to baryon or lepton number with a coupling greater than about 10{sup {minus}4} of gravitation per a.m.u. at ranges of about 0.5m and longer. In a few years the author hopes to test the weak equivalence principle with sensitivity exceeding 10{sup {minus}13}.

  18. Experimental performances study of a transportable GC-PID and two thermo-desorption based methods coupled to FID and MS detection to assess BTEX exposure at sub-ppb level in air.

    PubMed

    Liaud, C; Nguyen, N T; Nasreddine, R; Le Calvé, S

    2014-09-01

    BTEX compounds are of particular interest, above all benzene because it is a carcinogenic compound for which guideline value in European indoor environments is set to be 1.6 ppb. Therefore, the detection of such relatively low value requires the use of particularly sensitive analytical techniques. Several existing chromatographic techniques, such as fast and transportable Gas Chromatograph with Photoionization Detection (GC-PID) or sedentary chromatographic-based techniques equipped with a thermo-desorption device (ATD) and coupled to either Flame Ionization Detection (FID) or Mass Spectrometry (MS), can quantify benzene and its derivatives at such low levels. These instruments involve different injection modes, i.e. on-line gaseous sampling or thermo-desorption of adsorbent tubes spiked with liquid or gas samples. In this study, the performances of 3 various analytical techniques mentioned above were compared in terms of sensitivity, linearity, accuracy and repeatability for the 6 BTEX. They were also discussed related to their analyses time consumption or transportability. The considered analytical techniques are ATD-GC-FID, ATD-GC-MS where both full scan and SIM modes were tested and a transportable GC-PID. For benzene with on-line injection, Limits of Detection (LOD) were significantly below the European guideline with values of 0.085, 0.022, 0.007 and 0.058 ppb for ATD-GC-FID, ATD-GC-MS in a full scan mode, ATD-GC-MS in an SIM mode and transportable GC-PID, respectively. LOD obtained with adsorbent tubes spiked with liquid standards were approximately in the same order of magnitude.

  19. Pooled exposure assessment for matched case-control studies.

    PubMed

    Saha-Chaudhuri, Paramita; Umbach, David M; Weinberg, Clarice R

    2011-09-01

    Exposure assessment using biologic specimens is important for epidemiology but may become impracticable if assays are expensive, specimen volumes are marginally adequate, or analyte levels fall below the limit of detection. Pooled exposure assessment can provide an effective remedy for these problems in unmatched case-control studies. We extend pooled exposure strategies to handle specimens collected in a matched case-control study. We show that if a logistic model applies to individuals, then a logistic model also applies to an analysis using pooled exposures. Consequently, the individual-level odds ratio can be estimated while conserving both cost and specimen. We discuss appropriate pooling strategies for a single exposure, with adjustment for multiple, possibly continuous, covariates (confounders) and assessment of effect modification by a categorical variable. We assess the performance of the approach via simulations and conclude that pooled strategies can markedly improve efficiency for matched as well as unmatched case-control studies.

  20. Human Exposures to PAHs: an Eastern United States Pilot Study

    EPA Science Inventory

    Personal exposure monitoring for select polycyclic aromatic hydrocarbons (PAHs) was performed as part of the National Human Exposure Assessment Survey (NHEXAS) Pilot Study in Baltimore, MD and in four surrounding counties (NHEXAS-Maryland). An objective of this effort was to esta...

  1. Interoceptive Assessment and Exposure in Panic Disorder: A Descriptive Study

    ERIC Educational Resources Information Center

    Schmidt, Norman B.; Trakowski, Jack

    2004-01-01

    Cognitive behavioral treatment (CBT) protocols for panic disorder (PD) typically include some form of interoceptive exposure (IE)--repeated exposure to internal sensations. Despite the widespread clinical use of IE, there is a notable absence of empirical reports about the nature of interoceptive assessments and IE. The present study was designed…

  2. Interoceptive Assessment and Exposure in Panic Disorder: A Descriptive Study

    ERIC Educational Resources Information Center

    Schmidt, Norman B.; Trakowski, Jack

    2004-01-01

    Cognitive behavioral treatment (CBT) protocols for panic disorder (PD) typically include some form of interoceptive exposure (IE)--repeated exposure to internal sensations. Despite the widespread clinical use of IE, there is a notable absence of empirical reports about the nature of interoceptive assessments and IE. The present study was designed…

  3. Human Exposures to PAHs: an Eastern United States Pilot Study

    EPA Science Inventory

    Personal exposure monitoring for select polycyclic aromatic hydrocarbons (PAHs) was performed as part of the National Human Exposure Assessment Survey (NHEXAS) Pilot Study in Baltimore, MD and in four surrounding counties (NHEXAS-Maryland). An objective of this effort was to esta...

  4. Exposure assessment for epidemiologic study of nuclear workers potentially exposed to beryllium

    SciTech Connect

    Tankersley, W.G.; Cragle, D.L.; Hicks, N.V.; Googin, J.M.; Bean, G.L.

    1992-10-01

    In response to increased concern about possible exposure of Department of Energy workers to beryllium in the past, a pilot study was initiated to determine if an exposed population at Y-12 could be defined and to test the sensitivity of experimental clinical methods for diagnosing beryllium hypersensitivity.

  5. Exposure assessment for epidemiologic study of nuclear workers potentially exposed to beryllium

    SciTech Connect

    Tankersley, W.G.; Cragle, D.L.; Hicks, N.V. ); Googin, J.M.; Bean, G.L. )

    1992-01-01

    In response to increased concern about possible exposure of Department of Energy workers to beryllium in the past, a pilot study was initiated to determine if an exposed population at Y-12 could be defined and to test the sensitivity of experimental clinical methods for diagnosing beryllium hypersensitivity.

  6. Air Pollution Exposure Model for Individuals (EMI) in Health Studies

    EPA Science Inventory

    In health studies, traffic-related air pollution is associated with adverse respiratory effects. Due to cost and participant burden of personal measurements, health studies often estimate exposures using local ambient air monitors. Since outdoor levels do not necessarily reflect ...

  7. THE DETROIT EXPOSURE AND AEROSOL RESEARCH STUDY (DEARS)

    EPA Science Inventory

    Field data collections for the Detroit Exposure and Aerosol Research Study (DEARS) have completed one-half of the planned study design. The DEARS is collecting personal, residential indoor, residential outdoor and central community monitoring data involving particulate matter, v...

  8. THE DETROIT EXPOSURE AND AEROSOL RESEARCH STUDY (DEARS)

    EPA Science Inventory

    Field data collections for the Detroit Exposure and Aerosol Research Study (DEARS) have completed one-half of the planned study design. The DEARS is collecting personal, residential indoor, residential outdoor and central community monitoring data involving particulate matter, v...

  9. Air Pollution Exposure Model for Individuals (EMI) in Health Studies

    EPA Science Inventory

    In health studies, traffic-related air pollution is associated with adverse respiratory effects. Due to cost and participant burden of personal measurements, health studies often estimate exposures using local ambient air monitors. Since outdoor levels do not necessarily reflect ...

  10. Experimental model for ELF-EMF exposure: Concern for human health

    PubMed Central

    D’Angelo, C.; Costantini, E.; Kamal, M.A.; Reale, M.

    2014-01-01

    Low frequency (LF) electromagnetic fields (EMFs) are abundantly present in modern society and in the last 20 years the interest about the possible effect of extremely low frequency (ELF) EMFs on human health has increased progressively. Epidemiological studies, designed to verify whether EMF exposure may be a potential risk factor for health, have led to controversial results. The possible association between EMFs and an increased incidence of childhood leukemia, brain tumors or neurodegenerative diseases was not fully elucidated. On the other hand, EMFs are widely used, in neurology, psychiatry, rheumatology, orthopedics and dermatology, both in diagnosis and in therapy. In vitro studies may help to evaluate the mechanism by which LF-EMFs affect biological systems. Invitro model of wound healing used keratinocytes (HaCaT), neuroblastoma cell line (SH-SY5Y) as a model for analysis of differentiation, metabolism and functions related to neurodegenerative processes, and monocytic cell line (THP-1) was used as a model for inflammation and cytokines production, while leukemic cell line (K562) was used as a model for hematopoietic differentiation. MCP-1, a chemokine that regulates the migration and infiltration of memory T cells, natural killer (NK), monocytes and epithelial cells, has been demonstrated to be induced and involved in various diseases. Since, varying the parameters of EMFs different effects may be observed, we have studied MCP-1 expression in HaCaT, SH-SY5Y, THP-1 and K562 exposed to a sinusoidal EMF at 50 Hz frequency with a flux density of 1 mT (rms). Our preliminary results showed that EMF-exposure differently modifies the expression of MCP-1 in different cell types. Thus, the MCP-1 expression needs to be better determined, with additional studies, with different parameters and times of exposure to ELF-EMF. PMID:25561888

  11. Experimental model for ELF-EMF exposure: Concern for human health.

    PubMed

    D'Angelo, C; Costantini, E; Kamal, M A; Reale, M

    2015-01-01

    Low frequency (LF) electromagnetic fields (EMFs) are abundantly present in modern society and in the last 20 years the interest about the possible effect of extremely low frequency (ELF) EMFs on human health has increased progressively. Epidemiological studies, designed to verify whether EMF exposure may be a potential risk factor for health, have led to controversial results. The possible association between EMFs and an increased incidence of childhood leukemia, brain tumors or neurodegenerative diseases was not fully elucidated. On the other hand, EMFs are widely used, in neurology, psychiatry, rheumatology, orthopedics and dermatology, both in diagnosis and in therapy. In vitro studies may help to evaluate the mechanism by which LF-EMFs affect biological systems. In vitro model of wound healing used keratinocytes (HaCaT), neuroblastoma cell line (SH-SY5Y) as a model for analysis of differentiation, metabolism and functions related to neurodegenerative processes, and monocytic cell line (THP-1) was used as a model for inflammation and cytokines production, while leukemic cell line (K562) was used as a model for hematopoietic differentiation. MCP-1, a chemokine that regulates the migration and infiltration of memory T cells, natural killer (NK), monocytes and epithelial cells, has been demonstrated to be induced and involved in various diseases. Since, varying the parameters of EMFs different effects may be observed, we have studied MCP-1 expression in HaCaT, SH-SY5Y, THP-1 and K562 exposed to a sinusoidal EMF at 50 Hz frequency with a flux density of 1 mT (rms). Our preliminary results showed that EMF-exposure differently modifies the expression of MCP-1 in different cell types. Thus, the MCP-1 expression needs to be better determined, with additional studies, with different parameters and times of exposure to ELF-EMF.

  12. The effect of Low Earth Orbit exposure on some experimental fluorine and silicon-containing polymers

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Young, Philip R.; Kalil, Carol G.; Chang, Alice C.; Siochi, Emilie J.

    1994-01-01

    Several experimental fluorine and silicon-containing polymers in film form were exposed to low Earth orbit (LEO) on a Space Shuttle flight experiment (STS-46, Evaluation of Oxygen Interaction with Materials, EOIM-3). The environmental parameters of primary concern were atomic oxygen (AO) and ultraviolet (UV) radiation. The materials were exposed to 2.3 plus or minus 0.1 x 10(exp 20) oxygen atoms/sq cm and 30.6 UV sun hours during the flight. In some cases, the samples were exposed at ambient, 120 C and 200 C. The effects of exposure on these materials were assessed utilizing a variety of characterization techniques including optical, scanning electron (SEM) and scanning tunneling (STM) microscopy, UV-visible (UV-VIS) transmission, diffuse reflectance infrared (DR-FTIR), x-ray photoelectron (XPS) spectroscopy, and in a few cases, gel permeation chromatography (GPC). In addition, weight losses of the films, presumably due to AO erosion, were measured. The fluorine-containing polymers exhibited significant AO erosion and exposed films were diffuse or 'frosted' in appearance and consequently displayed dramatic reductions in optical transmission. The silicon-containing films exhibited minimum AO erosion and the optical transmission of exposed films was essentially unchanged. The silicon near the exposed surface in the films was converted to silicate/silicon oxide upon AO exposure which subsequently provided protection for the underlying material. The silicon-containing epoxies are potentially useful as AO resistant coatings and matrix resins as they are readily processed into carbon fiber reinforced composites and cured via electron radiation.

  13. Hypertension and Exposure to Noise near Airports (HYENA): Study Design and Noise Exposure Assessment

    PubMed Central

    Jarup, Lars; Dudley, Marie-Louise; Babisch, Wolfgang; Houthuijs, Danny; Swart, Wim; Pershagen, Göran; Bluhm, Gösta; Katsouyanni, Klea; Velonakis, Manolis; Cadum, Ennio; Vigna-Taglianti, Federica

    2005-01-01

    An increasing number of people live near airports with considerable noise and air pollution. The Hypertension and Exposure to Noise near Airports (HYENA) project aims to assess the impact of airport-related noise exposure on blood pressure (BP) and cardiovascular disease using a cross-sectional study design. We selected 6,000 persons (45–70 years of age) who had lived at least 5 years near one of six major European airports. We used modeled aircraft noise contours, aiming to maximize exposure contrast. Automated BP instruments are used to reduce observer error. We designed a standardized questionnaire to collect data on annoyance, noise disturbance, and major confounders. Cortisol in saliva was collected in a subsample of the study population (n = 500) stratified by noise exposure level. To investigate short-term noise effects on BP and possible effects on nighttime BP dipping, we measured 24-hr BP and assessed continuous night noise in another sub-sample (n = 200). To ensure comparability between countries, we used common noise models to assess individual noise exposure, with a resolution of 1 dB(A). Modifiers of individual exposure, such as the orientation of living and bedroom toward roads, window-opening habits, and sound insulation, were assessed by the questionnaire. For four airports, we estimated exposure to air pollution to explore modifying effects of air pollution on cardiovascular disease. The project assesses exposure to traffic-related air pollutants, primarily using data from another project funded by the European Union (APMoSPHERE, Air Pollution Modelling for Support to Policy on Health and Environmental Risks in Europe). PMID:16263498

  14. Experimental percolation studies of random networks

    NASA Astrophysics Data System (ADS)

    Feinerman, A.; Weddell, J.

    2017-06-01

    This report establishes an experimental method of studying electrically percolating networks at a higher resolution than previously implemented. This method measures the current across a conductive sheet as a function of time as elliptical pores are cut into the sheet. This is done utilizing a Universal Laser System X2-600 100 W CO2 laser system with a 76 × 46 cm2 field and 394 dpc (dots/cm) resolution. This laser can cut a random system of elliptical pores into a conductive sheet with a potential voltage applied across it and measures the current versus time. This allows for experimental verification of a percolation threshold as a function of the ellipse's aspect ratio (minor/major diameter). We show that as an ellipse's aspect ratio approaches zero, the percolation threshold approaches one. The benefit of this method is that it can experimentally measure the effect of removing small pores, as well as pores with complex geometries, such as an asterisk from a conductive sheet.

  15. Sun exposure and melanoma survival: a GEM study.

    PubMed

    Berwick, Marianne; Reiner, Anne S; Paine, Susan; Armstrong, Bruce K; Kricker, Anne; Goumas, Chris; Cust, Anne E; Thomas, Nancy E; Groben, Pamela A; From, Lynn; Busam, Klaus; Orlow, Irene; Marrett, Loraine D; Gallagher, Richard P; Gruber, Stephen B; Anton-Culver, Hoda; Rosso, Stefano; Zanetti, Roberto; Kanetsky, Peter A; Dwyer, Terry; Venn, Alison; Lee-Taylor, Julia; Begg, Colin B

    2014-10-01

    We previously reported a significant association between higher UV radiation exposure before diagnosis and greater survival with melanoma in a population-based study in Connecticut. We sought to evaluate the hypothesis that sun exposure before diagnosis was associated with greater survival in a larger, international population-based study with more detailed exposure information. We conducted a multicenter, international population-based study in four countries-Australia, Italy, Canada, and the United States-with 3,578 cases of melanoma with an average of 7.4 years of follow-up. Measures of sun exposure included sunburn, intermittent exposure, hours of holiday sun exposure, hours of water-related outdoor activities, ambient ultraviolet B (280-320 nm) dose, histologic solar elastosis, and season of diagnosis. Results were not strongly supportive of the earlier hypothesis. Having had any sunburn in 1 year within 10 years of diagnosis was inversely associated with survival; solar elastosis-a measure of lifetime cumulative exposure-was not. In addition, none of the intermittent exposure measures-water-related activities and sunny holidays-were associated with melanoma-specific survival. Estimated ambient UVB dose was not associated with survival. Although there was an apparent protective effect of sunburns within 10 years of diagnosis, there was only weak evidence in this large, international, population-based study of melanoma that sun exposure before diagnosis is associated with greater melanoma-specific survival. This study adds to the evidence that sun exposure before melanoma diagnosis has little effect on survival with melanoma. ©2014 American Association for Cancer Research.

  16. Sun Exposure and Melanoma Survival: A GEM Study

    PubMed Central

    Berwick, Marianne; Reiner, Anne S.; Paine, Susan; Armstrong, Bruce K.; Kricker, Anne; Goumas, Chris; Cust, Anne E.; Thomas, Nancy E.; Groben, Pamela A.; From, Lynn; Busam, Klaus; Orlow, Irene; Marrett, Loraine D.; Gallagher, Richard P.; Gruber, Stephen B.; Anton-Culver, Hoda; Rosso, Stefano; Zanetti, Roberto; Kanetsky, Peter A.; Dwyer, Terry; Venn, Alison; Lee-Taylor, Julia; Begg, Colin B.

    2014-01-01

    Background We previously reported a significant association between higher ultraviolet radiation exposure before diagnosis and greater survival with melanoma in a population-based study in Connecticut. We sought to evaluate the hypothesis that sun exposure prior to diagnosis was associated with greater survival in a larger, international population-based study with more detailed exposure information. Methods We conducted a multi-center, international population-based study in four countries – Australia, Italy, Canada and the United States – with 3,578 cases of melanoma with an average of 7.4 years of follow-up. Measures of sun exposure included sunburn, intermittent exposure, hours of holiday sun exposure, hours of water-related outdoor activities, ambient UVB dose, histological solar elastosis and season of diagnosis. Results Results were not strongly supportive of the earlier hypothesis. Having had any sunburn in one year within 10 years of diagnosis was inversely associated with survival; solar elastosis – a measure of lifetime cumulative exposure – was not. Additionally, none of the intermittent exposure measures – water related activities and sunny holidays - were associated with melanoma-specific survival. Estimated ambient UVB dose was not associated with survival. Conclusion Although there was an apparent protective effect of sunburns within 10 years of diagnosis, there was only weak evidence in this large, international, population-based study of melanoma that sun exposure prior to diagnosis is associated with greater melanoma-specific survival. Impact This study adds to the evidence that sun exposure prior to melanoma diagnosis has little effect on survival with melanoma. PMID:25069694

  17. Continuous game dynamics: an experimental study.

    SciTech Connect

    Patelli, P.; Sato, Yuzuru

    2004-01-01

    In this paper we study an experiment with human agents strategically interacting in a game characterized by continuous time and continuous strategy space. The research is focused in studying the agents interaction dynamic under different experimental settings. The agents play a two person game that is an extension of the classic Cournot duopoly. Having agents making decision continuously allows us to track the temporal structure of strategy evolution very precisely. We can follow the agents continuous behavior evolution avoiding the data under-sampling. To our knowledge this is the first attempt to approach experimentally the continuous time decision making. We also emphasize that the focus of our work is not the Cournot model but rather the more general problem of studying the agents strategic interaction dynamic in continuous space time. Flaming the problem as the well studied Cournot Duopoly would be a good starting point. In economics dynamics studies the oligopoly model literature in both discrete and continuous time is one of the richest. There is also a vast literature in experimental economics about repeated games in general and more specifically in duopoly/oligopoly models. Cox and Walker studied whether subjects can learn to play the Cournot Duopoly strategies comparing the experimental results with the theoretical prediction of learning models. The Cox Walker experiment differs from our settings because it is in discrete time and is an evolutionary dynamics framework through a random matching mechanism of the experimental subjects. From the theoretical perspective many works have been focused in studying the Cournot model in a dynamical settings. Okuguchi and Szidarovsky formulated a continuous time version of the Cournot Oligopoly with multiproduct firms. They analyzed the stability of the equilibrium and proved that it is stable, under certain conditions, independently from the value of the adjustments. Chiarella and Khomin extended this analysis to

  18. Experimental Study of Dust Grain Charging

    NASA Technical Reports Server (NTRS)

    Spann, James F; Venturini, Catherine C.; Comfort, Richard H.; Mian, Abbas M.

    1999-01-01

    The results of an experimental study of the charging mechanisms of micron size dust grains are presented. Individual dust grains are electrodynamically suspended and exposed to an electron beam of known energy and flux, and to far ultraviolet radiation of known wavelength and intensity. Changes in the charge-to-mass ratio of the grain are directly measured as a function of incident beam (electron and/or photon), grain size and composition. Comparisons of our results to theoretical models that predict the grain response are presented.

  19. Experimental Study of Dust Grain Charging

    NASA Technical Reports Server (NTRS)

    Spann, James F; Venturini, Catherine C.; Comfort, Richard H.; Mian, Abbas M.

    1999-01-01

    The results of an experimental study of the charging mechanisms of micron size dust grains are presented. Individual dust grains are electrodynamically suspended and exposed to an electron beam of known energy and flux, and to far ultraviolet radiation of known wavelength and intensity. Changes in the charge-to-mass ratio of the grain are directly measured as a function of incident beam (electron and/or photon), grain size and composition. Comparisons of our results to theoretical models that predict the grain response are presented.

  20. Experimental Study of Active Vibration Control.

    DTIC Science & Technology

    1983-04-15

    final versions of these reports will be sent to AFOSR. III. PUBLICATIONS ANTICIPATED 1. M . A. Masse, W. L. Hallauer Jr., and R. N. Gehling , "A Plane Grid...REPORT NUMBER 12. GOVT ACCESSION NO. S . RECIPIENT’S CATALOC NUMBER AFDSR -Th.O 3-p s .I * - J/POTt 4. TITLE (Me Su"Ide) S . TYPE OF REPORT & PERIOD...COVERED EXPERIMENTAL STUDY OF ACTIVE VIBRATION AN14UAL: CONTROL 15 MAR 82-14 MAR 83 S . PERFORMING ORG. REPORT NUMBER 7. AUTHOR(e) I. CONTRACT OR GRANT

  1. Experimental Study of Active Vibration Control.

    DTIC Science & Technology

    1983-10-27

    83 RFOSR-TR-84-8955 UNCLASSIFIED F S -28iF0 /iN E7 hFOS-hK!IilF/h2011 l I ALF 1 M2 11111.121 MICROCOPY RESOLUTION TEST CHART NATONAL SVlCAU O...34)g 4(GMO 2. OVTACSSION No.3. RECIPIENTSCTLGNBE 4. TITLE (and Subtitle) S . TYPE OF REPORT & PERIOD COVERED EXPERIMENTAL STUDY OF ACTIVE VIBRATION...CONTROL Final Scientific Report Mar. 15, 1982-Aug. 31, 1983 6. PERFORMING OIG. REPORT NUMBER 7. AUTHOR(&) S . CONTRACT OR GRANT NUMBER( s ) William L

  2. Experimental Study of Nucleon Structure and QCD

    SciTech Connect

    Jian-Ping Chen

    2012-03-01

    Overview of Experimental Study of Nucleon Structure and QCD, with focus on the spin structure. Nucleon (spin) Structure provides valuable information on QCD dynamics. A decade of experiments from JLab yields these exciting results: (1) valence spin structure, duality; (2) spin sum rules and polarizabilities; (3) precision measurements of g{sub 2} - high-twist; and (4) first neutron transverse spin results - Collins/Sivers/A{sub LT}. There is a bright future as the 12 GeV Upgrade will greatly enhance our capability: (1) Precision determination of the valence quark spin structure flavor separation; and (2) Precision extraction of transversity/tensor charge/TMDs.

  3. Experimental Study of Electronic States at Interfaces.

    DTIC Science & Technology

    1987-01-01

    relaxation time of 4 to 20 conduction band back to the bound states is long nsec is obtained, inspection of the phonon density-of- enough then the Is...AiBI 929 EXPERIMENTAL STUDY OF ELECTRONIC STATES AT INTERFACES 1/1 STATE PNVSICS A J SIEVERS 1987 AFOSR-TR-87-0851 U LSIFIE D AFOSR-8885 - FG 2112 L...NAME OF MONITORING ORGANIZATION i (~able) AORN Cornell University 9 e) AFOSR/NE 6c. ADDRESS (City, State , and ZIP Code) 7b ADDRESS (City, State , and

  4. A simulation study to quantify the impacts of exposure ...

    EPA Pesticide Factsheets

    BackgroundExposure measurement error in copollutant epidemiologic models has the potential to introduce bias in relative risk (RR) estimates. A simulation study was conducted using empirical data to quantify the impact of correlated measurement errors in time-series analyses of air pollution and health.MethodsZIP-code level estimates of exposure for six pollutants (CO, NOx, EC, PM2.5, SO4, O3) from 1999 to 2002 in the Atlanta metropolitan area were used to calculate spatial, population (i.e. ambient versus personal), and total exposure measurement error.Empirically determined covariance of pollutant concentration pairs and the associated measurement errors were used to simulate true exposure (exposure without error) from observed exposure. Daily emergency department visits for respiratory diseases were simulated using a Poisson time-series model with a main pollutant RR = 1.05 per interquartile range, and a null association for the copollutant (RR = 1). Monte Carlo experiments were used to evaluate the impacts of correlated exposure errors of different copollutant pairs.ResultsSubstantial attenuation of RRs due to exposure error was evident in nearly all copollutant pairs studied, ranging from 10 to 40% attenuation for spatial error, 3–85% for population error, and 31–85% for total error. When CO, NOx or EC is the main pollutant, we demonstrated the possibility of false positives, specifically identifying significant, positive associations for copoll

  5. A simulation study to quantify the impacts of exposure ...

    EPA Pesticide Factsheets

    BackgroundExposure measurement error in copollutant epidemiologic models has the potential to introduce bias in relative risk (RR) estimates. A simulation study was conducted using empirical data to quantify the impact of correlated measurement errors in time-series analyses of air pollution and health.MethodsZIP-code level estimates of exposure for six pollutants (CO, NOx, EC, PM2.5, SO4, O3) from 1999 to 2002 in the Atlanta metropolitan area were used to calculate spatial, population (i.e. ambient versus personal), and total exposure measurement error.Empirically determined covariance of pollutant concentration pairs and the associated measurement errors were used to simulate true exposure (exposure without error) from observed exposure. Daily emergency department visits for respiratory diseases were simulated using a Poisson time-series model with a main pollutant RR = 1.05 per interquartile range, and a null association for the copollutant (RR = 1). Monte Carlo experiments were used to evaluate the impacts of correlated exposure errors of different copollutant pairs.ResultsSubstantial attenuation of RRs due to exposure error was evident in nearly all copollutant pairs studied, ranging from 10 to 40% attenuation for spatial error, 3–85% for population error, and 31–85% for total error. When CO, NOx or EC is the main pollutant, we demonstrated the possibility of false positives, specifically identifying significant, positive associations for copoll

  6. Organ models in wound ballistics: experimental study.

    PubMed

    Ozer, Mustafa Tahir; Oğünç, Gökhan; Eryilmaz, Mehmet; Yiğit, Taner; Menteş, Mustafa Oner; Dakak, Mehmet; Uzar, Ali Ihsan; Oner, Köksal

    2007-01-01

    Effects of various types and diameters of guns and related treatment principles are different. Our study was performed to experimentally demonstrate the effects of different gunshots in body tissues. 9x19 mm hand-gun and 7.62x51 mm G-3 infantry rifle were used in the study. Injury models were created through hand-gun and rifle shootings at isolated soft tissue, lower extremity, liver and intestine tissue simulants made of ballistic candle. High-speed cameras were used to capture 1000 frames per second. Images were examined and wound mechanisms were evaluated. It was observed that the colon content distributed more within the surrounding tissues by the rifle shootings comparing with hand-gun shootings and could be an infection source due to the large size of the cavity in the colon. Especially when the bullets hitting the bone were investigated, it was seen that much more tissue injury occurs with high speed bullets due to bullet deformation and fragmentation. However, no significant difference was found between the effect of hand-gun and rifle bullets passing through the extremity without hitting the bone. To know the type of the gun that caused the injury and its characteristics will allow to estimate severity and size of the injury before the treatment and to focus on different alternatives of treatment. Therefore, use of appropriate models is required in experimental studies.

  7. Experimental Investigations of the Effects of Acid Gas (H2S/CO2) Exposure under Geological Sequestration Conditions

    NASA Astrophysics Data System (ADS)

    Hawthorne, S. B.; Miller, D.; Kutchko, B. G.; Strazisar, B. R.

    2009-12-01

    Acid gas (mixed CO2 and H2S) injection into geological formations is increasingly used as a disposal option. In contrast to pure CO2 injection, there is little understanding of the possible effects of acid gases under geological sequestration conditions on exposed materials ranging from reactions with reservoir minerals to the stability of proppants injected to improve oil recovery to the possible failure of well-bore cements. The number of laboratory studies investigating effects of acid gas has been limited by safety concerns and the difficulty in preparing and maintaining single-phase H2S/CO2 mixtures under the experimental pressures and temperatures required. We have developed approaches using conventional syringe pumps and reactor vessels to prepare and maintain H2S/CO2 mixtures under relevant sequestration conditions of temperature, pressure, and exposure to water and dissolved salts. These methods have been used to investigate and compare the effects of acid gas with those of pure CO2 on several materials including reservoir cores, oil recovery proppants, and well-bore cements, as well as to investigate the rates of model reactions such as the conversion of Fe3O4 to pyrite. The apparatus and methods used to perform acid gas exposures and representative results from the various exposed materials will be presented.

  8. Experimental methods in compressor noise studies

    NASA Astrophysics Data System (ADS)

    Lewy, S.; Jubelin, B.

    Rotating blade machines are a very important source of aeronautical noise. The present investigation is concerned with studies of noise generated by axial compressors, taking into account aircraft jet engines. The introduction of high bypass ratio engines for subsonic transportation led to a very pronounced improvement in performance and, in addition, also to a significant decrease in jet noise. The fan has now become the primary noise source. The theoretical background of compressor noise studies is examined, taking into account the resolution of the wave equation in a guided medium, the cut-off properties of a duct, azimuthal modes generated by a rotating source, and consequences of the theoretical model. The sound emission upstream of a compressor at subsonic and transonic speeds is considered along with details regarding the experimental methods suited to the study of compressor noise.

  9. Experimental Validation Plan for the Xolotl Plasma-Facing Component Simulator Using Tokamak Sample Exposures

    NASA Astrophysics Data System (ADS)

    Chan, V. S.; Wong, C. P. C.; McLean, A. G.; Luo, G. N.; Wirth, B. D.

    2013-10-01

    The Xolotl code under development by PSI-SciDAC will enhance predictive modeling capability of plasma-facing materials under burning plasma conditions. The availability and application of experimental data to compare to code-calculated observables are key requirements to validate the breadth and content of physics included in the model and ultimately gain confidence in its results. A dedicated effort has been in progress to collect and organize a) a database of relevant experiments and their publications as previously carried out at sample exposure facilities in US and Asian tokamaks (e.g., DIII-D DiMES, and EAST MAPES), b) diagnostic and surface analysis capabilities available at each device, and c) requirements for future experiments with code validation in mind. The content of this evolving database will serve as a significant resource for the plasma-material interaction (PMI) community. Work supported in part by the US Department of Energy under GA-DE-SC0008698, DE-AC52-07NA27344 and DE-AC05-00OR22725.

  10. Point: Incident Exposures, Prevalent Exposures, and Causal Inference: Does Limiting Studies to Persons Who Are Followed From First Exposure Onward Damage Epidemiology?

    PubMed Central

    Vandenbroucke, Jan; Pearce, Neil

    2015-01-01

    The idea that epidemiologic studies should start from first exposure onward has been advocated in the past few years. The study of incident exposures is contrasted with studies of prevalent exposures in which follow-up may commence after first exposure. The former approach is seen as a hallmark of a good study and necessary for causal inference. We argue that studying incident exposures may be necessary in some situations, but it is not always necessary and is not the preferred option in many instances. Conducting a study involves decisions as to which person-time experience should be included. Although studies of prevalent exposures involve left truncation (missingness on the left), studies of incident exposures may involve right censoring (missingness on the right) and therefore may not be able to assess the long-term effects of exposure. These considerations have consequences for studies of dynamic (open) populations that involve a mixture of prevalent and incident exposures. We argue that studies with prevalent exposures will remain a necessity for epidemiology. The purpose of this paper is to restore the balance between the emphasis on first exposure cohorts and the richness of epidemiologic information obtained when studying prevalent exposures. PMID:26507305

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

    NASA Astrophysics Data System (ADS)

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

    2006-09-01

    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.

  12. Incorporating exposure into aquatic toxicological studies: an imperative.

    PubMed

    Wang, Wen-Xiong

    2011-10-01

    The field of aquatic toxicology has been expanding rapidly in recent years. The ecotoxicological study of environmental toxicants encompasses three basic frameworks: environmental behavior/transport, bioavailability/bioaccumulation (exposure), and toxicity at different biological levels. Environmental risk assessments are then based on this knowledge to provide sound advice for environmental management and policies. In this article I will highlight the need to further understand the exposure to toxicants and its direct relationship with toxicological responses at different levels. Exposure considerations generally include the route, species, concentration and duration of exposure, among which the importance of the exposure route has been little considered. A typical aquatic toxicological study simply exposes the organisms to toxicants in the water for a certain period of time under different concentrations. This approach may not be environmentally relevant. Future studies should attempt to understand the toxicology under different exposure regimes. Incorporating exposure will allow aquatic toxicology to be placed in a context of environmental relevance and enhance our understanding of the impacts of toxicants on our living environments. 2011 Elsevier B.V. All rights reserved.

  13. Experimental Study of Top Heat Mode Thermosyphon

    NASA Astrophysics Data System (ADS)

    Hirashima, Masao; Kimura, Kenichiro; Utsumi, Yoichi; Kimura, Kenichi; Negishi, Kanji

    The purpose of this study is to develop the top heat mode thermosyphon that is very attractive means, for example, to accumulate directly the summer solar energy into the underground soil for the winter season. In this case, it can exclude the complex piping and mechanical pump to circulate the hot water absorbed the solar energy through the piping system buried in the soil layer. The several ideas concerning the top heat thermosyphon had been proposed, however, there were few reports on the definite experiments. The authors have carried out the experimental study of the top heat mode thermosyphon, with a simple lifting pipe, which could draw the working liquid from the under condenser to the upper evaporator section. The improvement of the main construction parts such as evaporator, lifting pipe, liquid reservoir trap and vapour nozzle have been performed in the present experiment in order to obtain the optimum operation range.

  14. Experimental studies of the magnetized friction force

    SciTech Connect

    Fedotov, A. V.; Litvinenko, V. N.; Gaalnander, B.; Lofnes, T.; Ziemann, V.; Sidorin, A.; Smirnov, A.

    2006-06-15

    High-energy electron cooling, presently considered as an essential tool for several applications in high-energy and nuclear physics, requires an accurate description of the friction force which ions experience by passing through an electron beam. Present low-energy electron coolers can be used for a detailed study of the friction force. In addition, parameters of a low-energy cooler can be chosen in a manner to reproduce regimes expected in future high-energy operation. Here, we report a set of dedicated experiments in CELSIUS aimed at a detailed study of the magnetized friction force. Some results of the accurate comparison of experimental data with the friction force formulas are presented.

  15. Retrograde arterialized venous flap: an experimental study.

    PubMed

    Moshammer, Harald E T; Schwarzl, Franz X; Haas, Franz M; Maechler, Heinrich; Pierer, Gerhard; Wiltgen, Marco; Koch, Horst

    2003-01-01

    An experimental model was established to study circulation in retrograde arterialized venous flaps (RAVF). Venous flaps measuring 7 x 4 cm with a matching venous system were harvested from both forearms of 10 fresh human cadavers. In each trial, both flaps were simultaneously perfused with heparinized human blood driven by a pulsatile circulation model. In each trial there was one flap with retrograde perfusion, and one flap with antegrade perfusion. Clinical assessment, measurement of outflow, and angiographic examination with digitally assisted assessment after 3 h of perfusion showed better results for retrograde perfusion in 8 of the 10 trials. This study indicates that blood circulation in the periphery of arterialized venous flaps can be enhanced by retrograde arterialization. Copyright 2003 Wiley-Liss, Inc.

  16. Subjective evaluation of experimental dyspnoea – Effects of isocapnia and repeated exposure

    PubMed Central

    Hayen, Anja; Herigstad, Mari; Wiech, Katja; Pattinson, Kyle T.S.

    2015-01-01

    Resistive respiratory loading is an established stimulus for the induction of experimental dyspnoea. In comparison to unloaded breathing, resistive loaded breathing alters end-tidal CO2 (PETCO2), which has independent physiological effects (e.g. upon cerebral blood flow). We investigated the subjective effects of resistive loaded breathing with stabilized PETCO2 (isocapnia) during manual control of inspired gases on varying baseline levels of mild hypercapnia (increased PETCO2). Furthermore, to investigate whether perceptual habituation to dyspnoea stimuli occurs, the study was repeated over four experimental sessions. Isocapnic hypercapnia did not affect dyspnoea unpleasantness during resistive loading. A post hoc analysis revealed a small increase of respiratory unpleasantness during unloaded breathing at +0.6 kPa, the level that reliably induced isocapnia. We did not observe perceptual habituation over the four sessions. We conclude that isocapnic respiratory loading allows stable induction of respiratory unpleasantness, making it a good stimulus for multi-session studies of dyspnoea. PMID:25578628

  17. Effects of pesticides on songbird productivity in conjunction with pecan cultivation in southern Georgia: A multiple-exposure experimental design

    USGS Publications Warehouse

    Patnode, K.A.; White, D.H.

    1991-01-01

    A prototypic experimental design was used to assess sublethal effects of multiple and varied organophosphates and carbamates on reproduction in birds. The design allowed for classification of pesticide exposure according to toxicity of applied compounds and type and frequency of applications. Daily survival rates (DSRs) of nests, eggs, and nestlings were determined for northern mockingbirds (Mimus polyglottos), brown thrashers (Toxostoma rufum), and northern cardinals (Cardinalis cardinalis) nesting along edges of pecan orchards and row crops in southern Georgia [USA]. Egg and nestling DSRs for all species combined varied inversely (P 0.05) among three exposure levels. Brain cholinesterase activities were age-dependent and substantiated adult, but not nestling, exposure. Results suggest that increasing exposure to pesticides may reduce songbird productivity.

  18. CO2 exposure as translational cross-species experimental model for panic

    PubMed Central

    Leibold, N K; van den Hove, D L A; Viechtbauer, W; Buchanan, G F; Goossens, L; Lange, I; Knuts, I; Lesch, K P; Steinbusch, H W M; Schruers, K R J

    2016-01-01

    The current diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders are being challenged by the heterogeneity and the symptom overlap of psychiatric disorders. Therefore, a framework toward a more etiology-based classification has been initiated by the US National Institute of Mental Health, the research domain criteria project. The basic neurobiology of human psychiatric disorders is often studied in rodent models. However, the differences in outcome measurements hamper the translation of knowledge. Here, we aimed to present a translational panic model by using the same stimulus and by quantitatively comparing the same outcome measurements in rodents, healthy human subjects and panic disorder patients within one large project. We measured the behavioral–emotional and bodily response to CO2 exposure in all three samples, allowing for a reliable cross-species comparison. We show that CO2 exposure causes a robust fear response in terms of behavior in mice and panic symptom ratings in healthy volunteers and panic disorder patients. To improve comparability, we next assessed the respiratory and cardiovascular response to CO2, demonstrating corresponding respiratory and cardiovascular effects across both species. This project bridges the gap between basic and human research to improve the translation of knowledge between these disciplines. This will allow significant progress in unraveling the etiological basis of panic disorder and will be highly beneficial for refining the diagnostic categories as well as treatment strategies. PMID:27598969

  19. Experimental exposure of male volunteers to N-methyl-2-pyrrolidone (NMP): acute effects and pharmacokinetics of NMP in plasma and urine.

    PubMed Central

    Akesson, B; Paulsson, K

    1997-01-01

    OBJECTIVES: To study the acute effects of exposure to the increasingly used solvent, N-methyl-2-pyrrolidone (NMP) in male volunteers. Further, to determine the NMP concentration in plasma and urine during and after the exposure. METHODS: Six male volunteers were exposed for eight hours on four different days to 0, 10, 25, and 50 mg/m3 NMP. Plasma was collected and urine was sampled during and after the exposure. Changes in nasal volume were measured by acoustic rhinometry and in airway resistance by spirometry. RESULTS: The eight-hour experimental exposure to 10, 25, and 50 mg/m3 did not induce discomfort to eyes or upper airways. Acute changes in nasal volume were not found, and no changes in the spirometric data could be registered. The elimination curves suggested a non-linear pattern and at the end of exposure showed mean (range) half lifes of NMP in plasma of about 4.0 (2.9-5.8) hours and in urine 4.5 (3.5-6.6) hours. The unmetabolised NMP found in urine samples collected during exposure and at the subsequent 44 hours corresponded to about 2% of the calculated absorbed dose. At the end of the exposure there was a close correlation between exposures and the plasma concentration and urinary excretion of NMP. CONCLUSIONS: NMP was absorbed through the respiratory tract and readily eliminated from the body, mainly by biotransformation to other compounds. Exposure to 10, 25, or 50 mg/m3 NMP did not cause nose, eye, or airway irritation. Thus, NMP is a mild irritant. PMID:9166128

  20. An Experimental Study of Soft Lubrication

    NASA Astrophysics Data System (ADS)

    Wu, Qianhong; Gacka, Thomas; Nathan, Rungun; Wu, Li-Zhu; Cbmss Team

    2012-11-01

    Lift generation in soft porous media, as a planing surface glides over it, is a new topic in porous media flow with superior potential for lubrication and squeeze damping. This paper presents the first experimental study of this phenomenon. The experimental setup consists of a running conveyer belt covered with a soft porous sheet, and a stationary instrumented inclined planar upper board. Twelve pressure transducers mounted on the upper board captured the pore pressure generation, while a load cell was used to capture the total lifting force, arising from both the pore pressure and the compression of the solid fibers. One finds that the pore pressure distribution is consistent with theoretical predictions (Feng and Weinbaum, JFM, 2000; Wu et al., MSSE, 2006, 2011), and depends on the running belt velocity, U, the mechanical properties of the porous material, and the compression ratios of the porous layer. For a typical trial (h2/h1=5,h2/h0=1, U=3.8 m/s, where h2, h1, and h0 are the leading edge, trailing edge, and undeformed porous layer thicknesses, respectively), 68% of the lifting force was generated by the pore pressure. It conclusively demonstrates the validity of using soft porous materials for super lubrication. applications. Villanova Cellular Biomechanics and Sports Science Laboratory.

  1. Experimental studies of quasi-fission reactions

    SciTech Connect

    Back, B.B.

    1988-01-01

    A large number of recent experimental studies have shown that a substantial fraction of the total reaction cross section in heavy-ion reactions is found in fission-like processes, which do not result from the fission decay of a completely fused system. Following the suggestion of Swiatecki such processes, which represents a complete relaxation of the relative kinetic energy and a substantial amount of net mass transfer between the two fragments, are denoted quasi-fission reactions. They are distinct from compound fission reactions by bypassing the stage of a completely fused-system. This typically means that they are associated with short reaction times, which results in several measurable characteristics such as broken forward-backward symmetries, large anisotropies of the angular distributions and increased widths of the fragment mass distributions. The distinction between quasi-fission and deep inelastic reactions is less stringent and has the character of a gradual evolution from one reaction type to the other, as found also as quasi-elastic reaction evolves into deeply inelastic processes as a function of the total kinetic energy loss. In the present paper some of the experimental data characterizing quasi-fission reactions are reviewed and discussed. 22 refs., 6 figs.

  2. [Experimental study of infectious hepatitis in guinea pigs].

    PubMed

    Asharafova, R A; Tuliaganov, P D; Kasymkhodzhaev, E S

    1976-04-01

    The authors carried out a comparative study of morphological changes in the liver of guinea-pigs in various times following intraperitoneal administration of the serum taken from a patient with infectious hepatitis (1st group), administration of the serum in combination with the urine (2nd group), administration of the serum in combination with the patient's duodenal juice (3rd group), and administration of the serum in combination with a hepatic antigen prepared of the liver of a healthy guinea-pig (4th group). Observations over the behaviour of the animals and morphological investigations showed a high sensitivity of guinea-pigs to virus-containing materials. The reaction was particularly pronounced in animals which were given the serum taken from a patient with infectious hepatitis in combination with a hepatic antigen, and the microscopic picture of the liver almost similar to that of the patient with Botkin's disease. Moreover, in the course of the study it was found possible to re-inoculate the virus obtained from the guinea-pigs subjected to a combined exposure to the serum from a patient with infectious hepatits and hepatic antigen. Comparing the results of the study on guinea-pigs with those obtained previously in the experimental study of viral hepatitis on white rats (1970), the authors have come to the conclusion that guinea-pigs may be used for modelling and experimental investigation of Botkin's disease.

  3. The Australian Work Exposures Study: prevalence of occupational exposure to diesel engine exhaust.

    PubMed

    Peters, Susan; Carey, Renee N; Driscoll, Timothy R; Glass, Deborah C; Benke, Geza; Reid, Alison; Fritschi, Lin

    2015-06-01

    Diesel engines are widely used in occupational settings. Diesel exhaust has been classified as a lung carcinogen, but data on number of workers exposed to different levels of diesel exhaust are not available in Australia. The aim of this study was to estimate the current prevalence of exposure to diesel engine exhaust in Australian workplaces. A cross-sectional survey of Australian males and females (18-65 years old) in current paid employment was undertaken. Information about the respondents' current job and various demographic factors was collected in a telephone interview using the web-based tool OccIDEAS. Semi-quantitative occupational exposure levels to diesel exhaust were assigned using programmed decision rules and numbers of workers exposed in Australia in 2011 were estimated. We defined substantial exposure as exposed at a medium or high level, for at least 5h per week. Substantial occupational exposure to diesel exhaust was experienced by 13.4% of the respondents in their current job. Exposure prevalence varied across states, ranging from 6.4% in the Australian Capital Territory to 17.0% in Western Australia. Exposures occurred mainly in the agricultural, mining, transport and construction industries, and among mechanics. Men (20.4%) were more often exposed than women (4.7%). Extrapolation to the total working population indicated that 13.8% (95% confidence interval 10.0-20.4) of the 2011 Australian workforce were estimated to be substantially exposed to diesel exhaust, and 1.8% of the workers were estimated to experience high levels of exposures in their current job. About 1.2 million Australian workers were estimated to have been exposed to diesel exhaust in their workplace in 2011. This is the first study to describe the prevalence of occupational diesel exhaust exposure in Australia and will enable estimation of the number of lung cancers attributable to diesel exhaust exposure in the workplace. © The Author 2015. Published by Oxford University Press

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

    PubMed Central

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

    2010-01-01

    Air monitoring surveys were conducted between 1998 and 2001 at seven non-metal mining facilities to assess exposure to respirable elemental carbon (REC), a component of diesel exhaust (DE), for an epidemiologic study of miners exposed to DE. Personal exposure measurements were taken on workers in a cross-section of jobs located underground and on the surface. Air samples taken to measure REC were also analyzed for respirable organic carbon (ROC). Concurrent measurements to assess exposure to nitric oxide (NO) and nitrogen dioxide (NO2), two gaseous components of DE, were also taken. The REC measurements were used to develop quantitative estimates of average exposure levels by facility, department, and job title for the epidemiologic analysis. Each underground job was assigned to one of three sets of exposure groups from specific to general: (i) standardized job titles, (ii) groups of standardized job titles combined based on the percentage of time in the major underground areas, and (iii) larger groups based on similar area carbon monoxide (CO) air concentrations. Surface jobs were categorized based on their use of diesel equipment and proximity to DE. A total of 779 full-shift personal measurements were taken underground. The average REC exposure levels for underground jobs with five or more measurements ranged from 31 to 58 μg m−3 at the facility with the lowest average exposure levels and from 313 to 488 μg m−3 at the facility with the highest average exposure levels. The average REC exposure levels for surface workers ranged from 2 to 6 μg m−3 across the seven facilities. There was much less contrast in the ROC compared with REC exposure levels measured between surface and underground workers within each facility, as well as across the facilities. The average ROC levels underground ranged from 64 to 195 μg m−3, while on the surface, the average ROC levels ranged from 38 to 71 μg m−3 by facility, an ∼2- to 3-fold difference. The average NO and

  5. Effects of chronic normobaric hypoxic and hypercapnic exposure in rats: Prevention of experimental chronic mountain sickness by hypercapnia

    NASA Astrophysics Data System (ADS)

    Lincoln, B.; Bonkovsky, H. L.; Ou, Lo-Chang

    1987-09-01

    A syndrome of experimental chronic mountain sickness can be produced in the Hilltop strain of Sprague-Dawley rats by chronic hypobaric hypoxic exposure. This syndrome is characterized by polycythemia, plasma hemoglobinemia, pulmonary hypertension and right ventricular hypertrophy with eventual failure and death. It has generally been assumed that these changes are caused by chronic hypoxemia, not by hypobaric exposure per se. We have now confirmed this directly by showing that chronic normobaric hypoxic exposure (10.5% O2) produces similar hematologic and hemodynamic changes. Further, the addition of hypercapnic exposure to the hypoxic exposure blunted or prevented the effects of the hypoxic exposure probably by stimulating respiration, thus increasing the rate of oxygen delivery to the cells. Changes in the rate-controlling enzymes of hepatic heme metabolism, 5-aminolevulinate synthase and heme oxygenase, and in cytochrome(s) P-450, the major hepatic hemoprotein(s), were also measured in hypoxic and hypercapnic rats. Hypoxia decreased 5-aminolevulinate synthase and increased cytochrome(s) P-450, probably by increasing the size of a “regulatory” heme pool within hepatocytes. These changes were also prevented by the addition of hypercapnic to hypoxic exposure.

  6. Modeling Air Pollution Exposure Metrics for the Diabetes and Environment Panel Study (DEPS)

    EPA Science Inventory

    Air pollution health studies of fine particulate matter (PM) often use outdoor concentrations as exposure surrogates. To improve exposure assessments, we developed and evaluated an exposure model for individuals (EMI), which predicts five tiers of individual-level exposure metric...

  7. IDENTIFICATION OF TIME-INTEGRATED SAMPLING AND MEASUREMENT TECHNIQUES TO SUPPORT HUMAN EXPOSURE STUDIES

    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. ...

  8. Modeling Air Pollution Exposure Metrics for the Diabetes and Environment Panel Study (DEPS)

    EPA Science Inventory

    Air pollution health studies of fine particulate matter (PM) often use outdoor concentrations as exposure surrogates. To improve exposure assessments, we developed and evaluated an exposure model for individuals (EMI), which predicts five tiers of individual-level exposure metric...

  9. Exposure assessment methods for a study of mortality and cancer morbidity in relation to specific petroleum industry exposures.

    PubMed

    Drummond, Ian; Murray, Neil; Armstrong, Thomas; Schnatter, A Robert; Lewis, R Jeffrey

    2006-10-01

    In 1987 a Canadian company implemented an exposure tracking and health information system. The exposure tracking method aligned closely with published concepts for describing workplace exposure, with over 1800 similar exposure groups being used to describe occupational exposures. The database has been actively maintained and is subject to a number of quality checks. Recently, the company initiated a cancer morbidity study, with one objective being to examine whether the exposure tracking data could be used to reconstruct exposure estimates for the cohort. Five agents--hydrogen sulfide, petroleum coke/spent catalyst, hydrocarbon solvents and fuels, hydrocarbon lubricants, and an index for exposure to operations derived from noise exposure--were selected for development of occupational exposure estimates for each cohort member. The cohort consisted of workers first employed between January 1964 and December 1994 and who were employed for at least 1 year. Work history records were associated with a similar exposure group, using human resources data and knowledge of local industrial hygienists. Only employees with >90% duration of their work history assigned were kept in the cohort (25,292 people out of a possible 25,617). For each similar exposure group inventory, the substances were identified that contributed to each of the five agents being studied. Exposure estimates before 1987 were modified using historic occupational exposure limits. Rules were created to sum the exposure from multiple substances found in any one similar exposure group. The validity of exposure estimates was tested via comparison with results documented in industrial hygiene survey reports. Industrial hygienists who were unaware of the derived exposure estimates evaluated several hundred industrial hygiene surveys and prepared benchmark information. The two lists were then evaluated for concordance, which was found to be significantly different from that occurring by chance. We conclude that

  10. Experimental and theoretical studies in nonlinear aeroelasticity

    NASA Astrophysics Data System (ADS)

    Attar, Peter Joseph

    Experimental and theoretical studies are conducted in the field of nonlinear aeroelasticity. Specifically two aeroelastic configurations, a flapping flag and a delta wing, are investigated and correlations between theory and experiment are presented. Two nonlinear structural theories are used to describe the structural behavior of the two models which are studied. The delta wing structural behavior is modeled using the nonlinear plate theory of von Karman. The nonlinearity in this model is due to the coupling between the out-of-plane and in-plane deflections and the model allows for moderately large out-of-plane plate deflections. The flapping flag structural model is a nonlinear beam theory which includes nonlinearities due to both large curvature and inertia. The axial deflection in this model is related to the out-of-plane deflection using an axially inextensible theory. The aerodynamic theory used is potential flow theory, which is applicable to low speed flows. The equation which describes potential flow is the Laplace equation, which is a linear partial differential equation. The Laplace equation is solved using a vortex lattice method. Aeroelastic solutions are found using both the classic small disturbance linearized fluid-structure interface boundary condition and the exact nonlinear boundary condition. The aeroelastic model which includes the nonlinear boundary conditions also includes a free wake solution. Several reduced order methods are explored. Normal mode solutions, both for the structural and aerodynamic models, are studied along with a proper orthogonal decomposition model for the aerodynamic flow. A brief description of a parallel implementation of the aeroelastic simulation code is also given and the parallel speedup is shown to be nearly linear for a certain class of problems. Correlation between theory and experiment is presented for both the delta wing and flapping flag model. Several steady angle of attack cases were investigated for the

  11. Effects of experimental long-term CO2 exposure on Daphnia magna (Straus 1820): From physiological effects to ecological consequences.

    PubMed

    Parra, Gema; Galotti, Andréa; Jiménez-Melero, Raquel; Guerrero, Francisco; Sánchez-Moyano, Emilio; Jiménez-Gómez, Francisco; Conradi, Mercedes

    2016-08-01

    The carbon capture and storage (CCS) technologies that were proposed to mitigate environmental problems arising from anthropogenic CO2 emissions, also have potential environmental risks. An eventual CCS leak might induce very low pH values in the aquatic system. Due to the lack of knowledge of long-term CO2 exposures with very low pH values, this study aims to know the effects and consequences of such a situation for zooplankton, using the Daphnia magna experimental model. A CO2 injection system was used to provide the experimental condition. A twenty-one days experiment with control and low pH treatment (pH = 7) replicates was carried out under light and temperature-controlled conditions. Survival, individual growth, RNA:DNA ratio, and neonates production were analysed during the aforementioned period. No differences on survival (except last day), individual growth and RNA:DNA ratio were observed between both control and low pH treatments. However, clear differences were detected in neonates production and, consequently, in population growth rates and secondary production. The observed differences could be related with an energy allocation strategy to ensure individual survival but would have ecological consequences affecting higher trophic levels. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. [Endodontics in horses. An experimental study].

    PubMed

    Garcia, F; Sanromán, F; Llorens, M P

    1990-04-01

    A total of 44 experimental endodontic treatments were performed in incisors of eight horses of different ages. Four different endodontic pastes were used: Cloropercha, AH26 De Trey, Eugenol-Endometasone, and Universal N2. Gutta-percha points were also included in the last two treatments. Access to the pulp cavity of incisors was gained through their vestibular and occlusal faces. Holes drilled in vestibular faces were sealed with composite and those drilled in occlusal faces were sealed with Amalgama. Animals were observed during eighteen months at least after endodontics. Radiographic controls were done just after surgery and before slaughtering. Treated incisors and alveoli were studied histopathologically. During the experiment all animals were in good condition. They ate apparently without trouble, and neither clinical nor radiological signs were present.

  13. Lipid peroxidation in experimental uveitis: sequential studies.

    PubMed

    Goto, H; Wu, G S; Chen, F; Kristeva, M; Sevanian, A; Rao, N A

    1992-06-01

    Previously we have detected the occurrence of retinal lipid peroxidation initiated by phagocyte-derived oxygen radicals in experimental autoimmune uveitis (EAU). In the current studies, the confirmation of inflammation-mediated lipid peroxidation was proceeded further to include measurement of multiple parameters, including conjugated dienes, ketodienes, thiobarbituric acid reactive substances and fluorescent chromolipids. The assay for myeloperoxidase, a measure for the number of polymorphonuclear leukocytes in the inflammatory sites was also carried out. The levels of all these parameters were followed through the course of EAU development. The sequential evaluation of histologic changes using both light and electron microscopy was also carried out and the results were correlated with lipid peroxidation indices. These data suggest that the retinal lipid peroxidation plays a causative role in the subsequent retinal degeneration.

  14. Experimental Studies in Helicopter Vertical Climb Performance

    NASA Technical Reports Server (NTRS)

    McKillip, Robert M., Jr.

    1996-01-01

    Data and analysis from an experimental program to measure vertical climb performance on an eight-foot model rotor are presented. The rotor testing was performed using a unique moving-model facility capable of accurately simulating the flow conditions during axial flight, and was conducted from July 9, 1992 to July 16, 1992 at the Dynamic Model Track, or 'Long Track,' just prior to its demolition in August of 1992. Data collected during this brief test program included force and moment time histories from a sting-mounted strain gauge balance, support carriage velocity, and rotor rpm pulses. In addition, limited video footage (of marginal use) was recorded from smoke flow studies for both simulated vertical climb and descent trajectories. Analytical comparisons with these data include a series of progressively more detailed calculations ranging from simple momentum theory, a prescribed wake method, and a free-wake prediction.

  15. [Brackets and friction in orthodontics: experimental study].

    PubMed

    Ben Rejeb Jdir, Saloua; Tobji, Samir; Turki, Wiem; Dallel, Ines; Khedher, Nedra; Ben Amor, Adel

    2015-09-01

    Many authors have been involved in developing brackets in order to improve the quality, stability, speed and efficiency of orthodontic treatment. In order to reduce friction between bracket and archwire, new therapeutic approaches have been devised based on novel technologies. Among these innovative techniques, self-ligating brackets are increasingly popular. SLBs can be classified into several categories according to their mode of action and their materials. We performed an experimental study to compare the friction forces generated during the sliding of orthodontic archwires made from various alloys through conventional and self-ligating brackets. Results show the favorable influence of SLBs, compared to conventional systems using elastomeric or metal ligatures, on the level of friction, particularly when shape-memory Ni-Ti archwires are used. © EDP Sciences, SFODF, 2015.

  16. Experimental study of solar simulator mirror cryocontamination

    NASA Technical Reports Server (NTRS)

    Galjaev, V. L.; Makarov, A. A.; Afanassiev, N. A.

    1994-01-01

    The background and tasks formulation of the study of Solar Simulator collimation mirror cryocontamination in Large Thermal Vacuum Facility are outlined, research methods and experiment procedures are described, experimental relationships obtained are analyzed and practical recommendations are given. The accepted procedure of thermal vacuum tests as a rule defines the sequence of operations for verifying the spacecraft under test without taking into account measures for preventing Solar Simulator collimation mirror contamination and degradation. On the other hand, evacuation procedures is defined for conditions of achieving the required vacuum in the shortest possible time with using the available evacuation equipment at a regime close to the optimum one. Similarly, cryopanel cooling down cyclogram and test object preparation process are not analyzed from the viewpoint of ways of reducing environmental detrimental effects on thermal vacuum facility contamination-sensitive systems. Solar Simulator mirror contamination and its reflective characteristics change results in degradation of solar flux parameters and reduction of simulator continuous operation time. Methods of consideration of optical effects due to mirror surface contamination are actually missing. The effects themselves are not quite understood and data cited in literature as a rule, were obtained under conditions different from real thermal vacuum facility and therefore should be subjected to additional experimental verification. Only in the last few years contamination effect on optical surfaces degradation has been considered with using empirical relations. Mirror reflective properties degradation leads to the increase of Solar Simulator errors. This ultimately has an adverse effect on S/C ground development, schedule and cost of thermal vacuum tests. Besides, the mirror maintenance in operable state becomes more expensive. The present paper is dedicated to the study of Solar Simulator collimation

  17. Experimental study of solar simulator mirror cryocontamination

    NASA Technical Reports Server (NTRS)

    Galjaev, V. L.; Makarov, A. A.; Afanassiev, N. A.

    1994-01-01

    The background and tasks formulation of the study of Solar Simulator collimation mirror cryocontamination in Large Thermal Vacuum Facility are outlined, research methods and experiment procedures are described, experimental relationships obtained are analyzed and practical recommendations are given. The accepted procedure of thermal vacuum tests as a rule defines the sequence of operations for verifying the spacecraft under test without taking into account measures for preventing Solar Simulator collimation mirror contamination and degradation. On the other hand, evacuation procedures is defined for conditions of achieving the required vacuum in the shortest possible time with using the available evacuation equipment at a regime close to the optimum one. Similarly, cryopanel cooling down cyclogram and test object preparation process are not analyzed from the viewpoint of ways of reducing environmental detrimental effects on thermal vacuum facility contamination-sensitive systems. Solar Simulator mirror contamination and its reflective characteristics change results in degradation of solar flux parameters and reduction of simulator continuous operation time. Methods of consideration of optical effects due to mirror surface contamination are actually missing. The effects themselves are not quite understood and data cited in literature as a rule, were obtained under conditions different from real thermal vacuum facility and therefore should be subjected to additional experimental verification. Only in the last few years contamination effect on optical surfaces degradation has been considered with using empirical relations. Mirror reflective properties degradation leads to the increase of Solar Simulator errors. This ultimately has an adverse effect on S/C ground development, schedule and cost of thermal vacuum tests. Besides, the mirror maintenance in operable state becomes more expensive. The present paper is dedicated to the study of Solar Simulator collimation

  18. Experimental Studies of Coaxial Jet Flows

    NASA Astrophysics Data System (ADS)

    Behrouzi, Parviz; McGuirk, James J.

    An experimental study was carried out to investigate the effect of coaxial nozzle operating conditions on near-field jet plume development. The study was conducted in a low speed water tunnel as well as in a high-speed airflow nozzle test facility. Laser Doppler Anemometry (LDA) and Laser Induced Fluorescence (LIF) techniques were employed to identify the flow structure as well as the mean velocity and turbulence structure of a coaxial nozzle under low speed flow conditions. Schlieren flow visualization, LDA and nozzle wall static pressure measurement surveys were performed in high speed flows. The effect of a nozzle shroud on jet development was studied and found very effective on suppression of the shock cells and on reduction of turbulence levels within the core region. The effect of the outer and inner Nozzle Pressure Ratios on shock cell structure and the nozzle internal wall pressure field were documented. LDA measurements in the water tunnel confirmed that the flow pattern produced of the Reynolds numbers and velocity ratios selected for this study was typical of practically occurring developing jet flow fields. Sufficient measured profiles of velocities, turbulence quantities and nozzle wall static pressures as well as jet plume images have been captured to serve as benchmark validation data for time-averaged turbulence-model-based RANS CFD predictions.

  19. Experimental chronic obstructive lung disease. I. Bronchopulmonary changes induced in rabbits by prolonged exposure to formaldehyde.

    PubMed

    Ionescu, J; Marinescu, D; Tapu, V; Eskenasy, A

    1978-01-01

    The prolonged exposure to formaldehyde induces in the rabbit lung reactional and dystrophic changes involving the intrapulmonary bronchi, the bronchioli and the lung tissue. These changes are represented by bronchial cell hyperplasia with hypermucigenesis, extrusion of bronchial cells, bronchiolar hypermucigenesis, parcellary squamous metaplasia or necrobiosis of epithelia, thickening of bronchial and bronchiolar walls by subepithelial cell accumulations, destruction of musculo-elastic structures with stenosis or ectasia; the vascular reactions are hyperhaemic and proliferative with an obstructive and fibrous tendency; the parenchymal lesions are atelectasias, intralobular emphysema, and cellular thickening of alveolar walls and interlobular areas. The acid phosphatase, Tween-60-esterase, naphthol-AS-D-acetate-esterase, proline-oxidase and hydroxyproline-2-epimerase activities are increasing, while the leucyl-aminopeptidase and beta-glucuronidase ones are decreasing. The qualitative observations are completed and sustained by quanitative studies of mucous cell kinetics, of cell accumulations and differentiations.

  20. Radio frequency exposure in mobile phone users: implications for exposure assessment in epidemiological studies.

    PubMed

    Morrissey, Joseph J

    2007-01-01

    The majority of epidemiological studies investigating correlations between long-term low-level radiofrequency (RF) exposure from mobile phones and health endpoints have followed a case-control design, requiring reconstruction of individual RF exposure. To date, these have employed 'time of use' as an exposure surrogate from questionnaire information or billing records. The present study demonstrates such an approach may not account for variability in mobile phone transmit power, which can be roughly correlated with RF exposure. This variability exists (a) during a single call, (b) between separate calls, (c) between averaged values from individuals within a local study group and (d) between average values from groups in different geographical locations. The present data also suggest an age-related influence on talk time, as well as significant inaccuracy (45-60%) in recalling 'time of use'. Evolving technology and changing use behaviours may add additional complexities. Collectively, these data suggest efforts to identify dose response and statistical correlations between mobile phone use and subtle health endpoints may be significantly challenged.

  1. Micronuclei assay: A potential biomonitoring protocol in occupational exposure studies.

    PubMed

    Palanikumar, L; Panneerselvam, N

    2011-09-01

    As micronuclei (MN) derive from chromosomal fragments and whole chromosomes lagging behind in anaphase, the MN assay can be used to show both clastogenic and aneugenic effects. This particularly concerns the use of MN as a biomarker ofgenotoxic exposure and effects, where differences in MN frequencies between exposed subjects and referents are expected to be small. The present paper reviews the use of the MN assay in biomonitoring of occupational exposure studies.

  2. EXPOSURE ASSESSMENT FINDINGS FROM THE TAMPA ASTHMATIC CHILDREN'S STUDY (TACS)

    EPA Science Inventory

    The Tampa Asthmatic Children's Study (TACS) was a pilot study that focused on developing and evaluating air pollution exposure assessment methods and participant recruiting tools. The four-week study was performed in October and November, 2003. The study involved repeated daily...

  3. PRELIMINARY EXPOSURE ASSESSMENT FINDINGS FROM THE TAMPA ASTHMATIC CHILDREN'S STUDY

    EPA Science Inventory

    The Tampa Asthmatic Children's Study (TACS) was a pilot study that focused on developing and evaluating air pollution exposure assessment methods and participant recruiting tools. The four-week study was performed in October and November, 2003. The study involved repeated daily...

  4. EXPOSURE ASSESSMENT FINDINGS FROM THE TAMPA ASTHMATIC CHILDREN'S STUDY (TACS)

    EPA Science Inventory

    The Tampa Asthmatic Children's Study (TACS) was a pilot study that focused on developing and evaluating air pollution exposure assessment methods and participant recruiting tools. The four-week study was performed in October and November, 2003. The study involved repeated daily...

  5. PRELIMINARY EXPOSURE ASSESSMENT FINDINGS FROM THE TAMPA ASTHMATIC CHILDREN'S STUDY

    EPA Science Inventory

    The Tampa Asthmatic Children's Study (TACS) was a pilot study that focused on developing and evaluating air pollution exposure assessment methods and participant recruiting tools. The four-week study was performed in October and November, 2003. The study involved repeated daily...

  6. Exploring Selective Exposure and Confirmation Bias as Processes Underlying Employee Work Happiness: An Intervention Study.

    PubMed

    Williams, Paige; Kern, Margaret L; Waters, Lea

    2016-01-01

    Employee psychological capital (PsyCap), perceptions of organizational virtue (OV), and work happiness have been shown to be associated within and over time. This study examines selective exposure and confirmation bias as potential processes underlying PsyCap, OV, and work happiness associations. As part of a quasi-experimental study design, school staff (N = 69) completed surveys at three time points. After the first assessment, some staff (n = 51) completed a positive psychology training intervention. Results of descriptive statistics, correlation, and regression analyses on the intervention group provide some support for selective exposure and confirmation bias as explanatory mechanisms. In focusing on the processes through which employee attitudes may influence work happiness this study advances theoretical understanding, specifically of selective exposure and confirmation bias in a field study context.

  7. Exploring Selective Exposure and Confirmation Bias as Processes Underlying Employee Work Happiness: An Intervention Study

    PubMed Central

    Williams, Paige; Kern, Margaret L.; Waters, Lea

    2016-01-01

    Employee psychological capital (PsyCap), perceptions of organizational virtue (OV), and work happiness have been shown to be associated within and over time. This study examines selective exposure and confirmation bias as potential processes underlying PsyCap, OV, and work happiness associations. As part of a quasi-experimental study design, school staff (N = 69) completed surveys at three time points. After the first assessment, some staff (n = 51) completed a positive psychology training intervention. Results of descriptive statistics, correlation, and regression analyses on the intervention group provide some support for selective exposure and confirmation bias as explanatory mechanisms. In focusing on the processes through which employee attitudes may influence work happiness this study advances theoretical understanding, specifically of selective exposure and confirmation bias in a field study context. PMID:27378978

  8. Experimental Study of RF Pulsed Heating

    SciTech Connect

    Laurent, Lisa; Tantawi, Sami; Dolgashev, Valery; Nantista, Christopher; Higashi, Yasuo; Aicheler, Markus; Heikkinen, Samuli; Wuensch, Walter; /CERN

    2011-11-04

    Cyclic thermal stresses produced by rf pulsed heating can be the limiting factor on the attainable reliable gradients for room temperature linear accelerators. This is especially true for structures that have complicated features for wakefield damping. These limits could be pushed higher by using special types of copper, copper alloys, or other conducting metals in constructing partial or complete accelerator structures. Here we present an experimental study aimed at determining the potential of these materials for tolerating cyclic thermal fatigue due to rf magnetic fields. A special cavity that has no electric field on the surface was employed in these studies. The cavity shape concentrates the magnetic field on one flat surface where the test material is placed. The materials tested in this study have included oxygen free electronic grade copper, copper zirconium, copper chromium, hot isostatically pressed copper, single crystal copper, electroplated copper, Glidcop(reg. sign), copper silver, and silver plated copper. The samples were exposed to different machining and heat treatment processes prior to rf processing. Each sample was tested to a peak pulsed heating temperature of approximately 110 C and remained at this temperature for approximately 10 x 10{sup 6} rf pulses. In general, the results showed the possibility of pushing the gradient limits due to pulsed heating fatigue by the use of copper zirconium and copper chromium alloys.

  9. Experimental study of rf pulsed heating

    NASA Astrophysics Data System (ADS)

    Laurent, Lisa; Tantawi, Sami; Dolgashev, Valery; Nantista, Christopher; Higashi, Yasuo; Aicheler, Markus; Heikkinen, Samuli; Wuensch, Walter

    2011-04-01

    Cyclic thermal stresses produced by rf pulsed heating can be the limiting factor on the attainable reliable gradients for room temperature linear accelerators. This is especially true for structures that have complicated features for wakefield damping. These limits could be pushed higher by using special types of copper, copper alloys, or other conducting metals in constructing partial or complete accelerator structures. Here we present an experimental study aimed at determining the potential of these materials for tolerating cyclic thermal fatigue due to rf magnetic fields. A special cavity that has no electric field on the surface was employed in these studies. The cavity shape concentrates the magnetic field on one flat surface where the test material is placed. The materials tested in this study have included oxygen free electronic grade copper, copper zirconium, copper chromium, hot isostatically pressed copper, single crystal copper, electroplated copper, Glidcop®, copper silver, and silver plated copper. The samples were exposed to different machining and heat treatment processes prior to rf processing. Each sample was tested to a peak pulsed heating temperature of approximately 110°C and remained at this temperature for approximately 10×106 rf pulses. In general, the results showed the possibility of pushing the gradient limits due to pulsed heating fatigue by the use of copper zirconium and copper chromium alloys.

  10. Pulmonary paragonimiasis: clinical and experimental studies.

    PubMed

    Im, J G; Kong, Y; Shin, Y M; Yang, S O; Song, J G; Han, M C; Kim, C W; Cho, S Y; Ham, E K

    1993-05-01

    Pulmonary paragonimiasis is a disease caused by a lung fluke. It is endemic to East Asia, but there have been several case reports in North America. Human infestation occurs by ingestion of raw or incompletely cooked freshwater crab or crayfish infected with metacercaria. A retrospective study was performed with 78 patients who lived in South Korea and had chest radiographic findings of pleuropulmonary disease; it was subsequently shown that they had paragonimiasis. The diagnosis was based on positive results of serologic tests for Paragonimus-specific antibody or on the detection of eggs in sputum samples. Radiologic findings from these 78 patients were correlated with the pathologic and radiologic findings from a study of experimentally induced pulmonary paragonimiasis in 21 cats. Findings from the correlative study document that the typical radiologic manifestations of pulmonary paragonimiasis vary with the stage of the disease. Early findings include pneumothorax or hydropneumothorax, focal airspace consolidation, and linear opacities and are caused by the migration of juvenile worms. Later findings include thin-walled cysts, dense masslike consolidation, nodules, or bronchiectasis and are due to worm cysts.

  11. Experimental Study of Alluvial Fan Formation

    NASA Astrophysics Data System (ADS)

    Delorme, P.; Devauchelle, O.; Barrier, L.; Métivier, F.

    2015-12-01

    At the outlet of mountain ranges, rivers flow onto flatter lowlands. The associated change of slope causes sediment deposition. As the river is free to move laterally, it builds conical sedimentary structures called alluvial fans. Their location at the interface between erosional and depositional areas makes them valuable sedimentary archives. To decipher these sedimentary records, we need to understand the dynamics of their growth. Most natural fans are built by braided streams. However, to avoid the complexity of braided rivers, we develop a small-scale experiment in which an alluvial fan is formed by a single channel. We use a mixture of water and glycerol to produce a laminar river. The fluid is mixed with corindon sand (~ 300 μm) in a tilted channel and left free to form a fan around its outlet. The sediment and water discharges are constant during an experimental run. We record the fan progradation and the channel morphology with top-view pictures. We also generate an elevation map with an optical method based on the deformation of a moiré pattern. We observe that, to leading order, the fan remains self-affine as it grows, with a constant slope. We compare two recent studies about the formation of one-dimensionnal fan [Guerit et al. 2014] and threshold rivers [Seizilles et al. 2013] to our experimental findings. In particular, we propose a theory witch relates the fan morphology to the control parameters ( fluid and sediment discharges, grain size). Our observation accord with the predictions, suggesting that the fan is built near the threshold of sediment motion. Finally, we intend to expand our interpretation to alluvial fans build by single-thread channels ( Okavango, Bostwana; Taquari and Paraguay, Brasil; Pastaza, Peru).

  12. Exposure to airborne endotoxins among sewer workers: an exploratory study.

    PubMed

    Duquenne, Philippe; Ambroise, Denis; Görner, Pierre; Clerc, Frédéric; Greff-Mirguet, Guylaine

    2014-04-01

    Exploratory bioaerosol sampling was performed in order to assess exposure to airborne endotoxins during sewer work. Personal samples were collected in underground sewer pipes using 37-mm closed-face cassettes containing fibreglass filters (CFC-FG method) or polycarbonate filters (CFC-PC method). Endotoxins were quantified using the limulus amoebocyte lysate assay. Concentrations of airborne endotoxins at sewer workplaces (16-420 EU m(-3)) were higher than those measured outside the sewer network (0.6-122 EU m(-3)). Sewer worker exposure to airborne endotoxins depended on the workplace and on the tasks. Exposure levels were the highest for tasks involving agitation of water and matter, especially for 'chamber cleanup' and 'pipes cleanup' with a high-pressure water jet. Airborne endotoxin levels at the workplace tended to be higher when CFC-FG was used as the sampling method rather than CFC-PC. The adjusted mean of the measured concentrations for CFC-PC represents 57% of the mean observed with CFC-FG. The number of samples collected in the descriptive study was too low for drawing definitive conclusions and further exposure investigations are needed. Therefore, our exploratory study provides new exposure data for the insufficiently documented sewer working environment and it would be useful for designing larger exposures studies.

  13. Cross-sectional study on respiratory effect of toner exposure.

    PubMed

    Terunuma, Niina; Kurosaki, Shizuka; Kitamura, Hiroko; Hata, Koichi; Ide, Reiko; Kuga, Hiroaki; Kakiuchi, Noriaki; Masuda, Masashi; Totsuzaki, Takafumi; Osato, Atsushi; Uchino, Bungo; Kitahara, Kayo; Iwasaki, Akio; Yoshizumi, Koji; Morimoto, Yasuo; Kasai, Hiroshi; Murase, Tadashi; Higashi, Toshiaki

    2009-06-01

    In this baseline study, part of a cohort study to clarify the effect of toner exposure on the respiratory system, we surveyed 803 male toner workers and 802 referents with regard to their subjective respiratory symptoms and chest X-ray results. We also examined individual exposure history, current working conditions, and personal exposure levels to toner. There was a significantly higher prevalence of "coughing and sputum" related complaints among toner-exposed workers in the 30 and 40-year age groups. The group with toner-exposure history showed a higher odds ratio, by logistic regression, in relation to all questions regarding coughing. Mild fibrotic changes were observed in the chest X-rays of four workers who had engaged in toner-exposure work for at least a decade or more, and all four had reported allergic disease. Although we observed a tendency of higher prevalence of "coughing and sputum" in toner-exposed workers, the possibility of information bias cannot be eliminated. It should also be noted that this tendency did not exceed that of the general public. Further analysis is required in this ongoing 10-year cohort study to clarify the effect of toner exposure on the respiratory system.

  14. Prospective study of chemical exposures and amyotrophic lateral sclerosis

    PubMed Central

    Weisskopf, MG; Morozova, N; O'Reilly, EJ; McCullough, ML; Calle, EE; Thun, MJ; Ascherio, A

    2009-01-01

    Background Although environmental toxins, including pesticides, are suspected of contributing to the risk of amyotrophic lateral sclerosis (ALS), no data exist from large prospective investigations. This study assessed the association between exposure to chemicals and risk of ALS in a prospective cohort study. Methods We prospectively assessed the relation between self-report of regular exposure to 11 different chemical classes or X-rays and ALS mortality among over 1 million participants in the American Cancer Society's Cancer Prevention Study II. Follow-up from 1989 through 2004 identified 617 deaths from ALS among men and 539 among women. We calculated adjusted rate ratios (RR) using Cox proportional hazards. Results The RR for ALS mortality among individuals exposed to pesticides/herbicides compared to the unexposed was 1.07 (95% confidence interval (CI): 0.79-1.44), but somewhat higher after excluding those with missing duration of pesticides exposure (RR: 1.44; 95% CI: 0.89-2.31; p=0.14). A non-significant increase in ALS mortality was found among individuals who reported exposure to formaldehyde (RR: 1.34; 95% CI: 0.93-1.92). Excluding those with missing duration of formaldehyde exposure, the RR was 2.47 (95% CI: 1.58-3.86), and there was a strongly significant dose-response relation with increasing years of exposure (p-trend=0.0004). Conclusions We found little evidence for an association between pesticides/herbicide exposure and ALS. In contrast, we found evidence suggesting an increased risk of ALS with formaldehyde exposure. Because of the longitudinal design, this result is unlikely to be due to bias, but it should nevertheless be interpreted cautiously and needs to be independently verified. PMID:19372290

  15. Malfunction of cardiac devices after radiotherapy without direct exposure to ionizing radiation: mechanisms and experimental data.

    PubMed

    Zecchin, Massimo; Morea, Gaetano; Severgnini, Mara; Sergi, Elisabetta; Baratto Roldan, Anna; Bianco, Elisabetta; Magnani, Silvia; De Luca, Antonio; Zorzin Fantasia, Anna; Salvatore, Luca; Milan, Vittorino; Giannini, Gianrossano; Sinagra, Gianfranco

    2016-02-01

    Malfunctions of cardiac implantable electronical devices (CIED) have been described after high-energy radiation therapy even in the absence of direct exposure to ionizing radiation, due to diffusion of neutrons (n) causing soft errors in inner circuits. The purpose of the study was to analyse the effect of scattered radiation on different types and models of CIED and the possible sources of malfunctions. Fifty-nine explanted CIED were placed on an anthropomorphous phantom of tissue-equivalent material, and a high-energy photon (15 MV) radiotherapy course (total dose = 70 Gy) for prostate treatment was performed. All devices were interrogated before and after radiation. Radiation dose, the electromagnetic field, and neutron fluence at the CIED site were measured. Thirty-four pacemakers (PM) and 25 implantable cardioverter-defibrillators (ICD) were analysed. No malfunctions were detected before radiation. After radiation a software malfunction was evident in 13 (52%) ICD and 6 (18%) PM; no significant electromagnetic field or photon radiations were detected in the thoracic region. Neutron capture was demonstrated by the presence of the (198)Au((197)Au + n) or (192)Ir((191)Ir + n) isotope activation; it was significantly greater in ICD than in PM and non-significantly greater in damaged devices. A greater effect in St Jude PM (2/2 damaged), Boston (9/11), and St Jude ICD (3/6) and in older ICD models was observed; the year of production was not relevant in PM. High-energy radiation can cause different malfunctions on CIED, particularly ICD, even without direct exposure to ionizing radiation due to scattered radiation of neutrons produced by the linear accelerator. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

  16. Acute radiation enteritis caused by dose-dependent radiation exposure in dogs: experimental research.

    PubMed

    Xu, Wenda; Chen, Jiang; Xu, Liu; Li, Hongyu; Guo, Xiaozhong

    2014-12-01

    Accidental or intended radiation exposure in mass casualty settings presents a serious and on-going threat. The development of mitigating and treating agents requires appropriate animal models. Unfortunately, the majority of research on radiation enteritis in animals has lacked specific assessments and targeted therapy. Our study showed beagle dogs, treated by intensity-modulated radiation therapy (IMRT) for abdominal irradiation, were administered single X-ray doses of 8-30 Gy. The degree of intestinal tract injury for all of the animals after radiation exposure was evaluated with regard to clinical syndrome, endoscopic findings, histological features, and intestinal function. The range of single doses (8 Gy, 10-14 Gy, and 16-30 Gy) represented the degree of injury (mild, moderate, and severe, respectively). Acute radiation enteritis included clinical syndrome with fever, vomiting, diarrhea, hemafecia, and weight loss; typical endoscopic findings included edema, bleeding, mucosal abrasions, and ulcers; and intestinal biopsy results revealed mucosal necrosis, erosion, and loss, inflammatory cell infiltration, hemorrhage, and congestion. Changes in serum diamine oxides (DAOs) and d-xylose represented intestinal barrier function and absorption function, respectively, and correlated with the extent of damage (P < 0.05 and P < 0.05, respectively). We successfully developed a dog model of acute radiation enteritis, thus obtaining a relatively objective evaluation of intestinal tract injury based on clinical performance and laboratory examination. The method of assessment of the degree of intestinal tract injury after abdominal irradiation could be beneficial in the development of novel and effective therapeutic strategies for acute radiation enteritis.

  17. Low-Level Fluoride Exposure Increases Insulin Sensitivity in Experimental Diabetes.

    PubMed

    Lobo, J G V M; Leite, A L; Pereira, H A B S; Fernandes, M S; Peres-Buzalaf, C; Sumida, D H; Rigalli, A; Buzalaf, M A R

    2015-07-01

    The effect of chronic fluoride (F) exposure from the drinking water on parameters related to glucose homeostasis was investigated. Wistar rats were randomly distributed into 2 groups (diabetic [D] and nondiabetic [ND]; n = 54 each). In D, diabetes was induced with streptozotocin. Each group was further divided into 3 subgroups (0, 10, or 50 mgF/L in drinking water). After 22 days of treatment, plasma and liver samples were collected. No alterations in glycemia, insulinemia, K(ITT), and HOMA2-IR (homeostasis model assessment 2 of insulin resistance) were seen for ND. F-exposure of D rats led to significantly lower insulinemia, without alterations in glycemia (increased %S). Proteomic analysis detected 19, 39, and 16 proteins differentially expressed for the comparisons D0 vs. D10, D0 vs. D50, and D10 vs. D50, respectively. Gene Ontology with the most significant terms in the comparisons D0 vs. D10, D0 vs. D50, and D50 vs. D10 were organic acid metabolic process and carboxylic acid metabolic process, organic acid metabolic process, and cellular ketone metabolic process. Analysis of subnetworks revealed that proteins with fold changes interacted with GLUT4 in comparison D0 vs. D10. Among these proteins, ERj3p was present in D10. Upregulation of this protein in the presence of F might help to explain the higher %S found in these animals. These data suggest that fluoride might enhance glucose homeostasis in diabetes and identify specific biological mechanisms that merit future studies.

  18. Idaho radionuclide exposure study: Literature review

    SciTech Connect

    Baker, E.G.; Freeman, H.D.; Hartley, J.N.

    1987-10-01

    Phosphate ores contain elevated levels of natural radioactivity, some of which is released to the environment during processing or use of solid byproducts. The effect of radionuclides from Idaho phosphate processing operations on the local communities has been the subject of much research and study. The literature is reviewed in this report. Two primary radionuclide pathways to the environment have been studied in detail: (1) airborne release of volatile radionuclides, primarily /sup 210/Po, from calciner stacks at the two elemental phosphorus plants; and (2) use of byproduct slag as an aggregate for construction in Soda Springs and Pocatello. Despite the research, there is still no clear understanding of the population dose from radionuclide emissions, effluents, and solid wastes from phosphate processing plants. Two other potential radionuclide pathways to the environment have been identified: radon exhalation from phosphogypsum and ore piles and contamination of surface and ground waters. Recommendations on further study needed to develop a data base for a complete risk assssment are given in the report.

  19. Experimental Study of Lift-Generated Vortices

    NASA Technical Reports Server (NTRS)

    Rossow, Vernon J.; Nixon, David (Technical Monitor)

    1998-01-01

    The flow fields of vortices, whether bouyancy-driven or lift-generated, are fascinating fluid-dynamic phenomena which often possess intense swirl velocities and complex time-dependent behavior. As part of the on-going study of vortex behavior, this paper presents a historical overview of the research conducted on the structure and modification of the vortices generated by the lifting surfaces of subsonic transport aircraft. It is pointed out that the characteristics of lift-generated vortices are related to the aerodynamic shapes that produce them and that various arrangements of surfaces can be used to produce different vortex structures. The primary purpose of the research to be described is to find a way to reduce the hazard potential of lift-generated vortices shed by subsonic transport aircraft in the vicinity of airports during landing and takeoff operations. It is stressed that lift-generated vortex wakes are so complex that progress towards a solution requires application of a combined theoretical and experimental research program because either alone often leads to incorrect conclusions. It is concluded that a satisfactory aerodynamic solution to the wake-vortex problem at airports has not yet been found but a reduction in the impact of the wake-vortex hazard on airport capacity may become available in the foreseeable future through wake-vortex avoidance concepts currently under study. The material to be presented in this overview is drawn from aerospace journals that are available publicly.

  20. Experimental methods in studying child language acquisition.

    PubMed

    Ambridge, Ben; Rowland, Caroline F

    2013-03-01

    This article reviews the some of the most widely used methods used for studying children's language acquisition including (1) spontaneous/naturalistic, diary, parental report data, (2) production methods (elicited production, repetition/elicited imitation, syntactic priming/weird word order), (3) comprehension methods (act-out, pointing, intermodal preferential looking, looking while listening, conditioned head turn preference procedure, functional neuroimaging) and (4) judgment methods (grammaticality/acceptability judgments, yes-no/truth-value judgments). The review outlines the types of studies and age-groups to which each method is most suited, as well as the advantage and disadvantages of each. We conclude by summarising the particular methodological considerations that apply to each paradigm and to experimental design more generally. These include (1) choosing an age-appropriate task that makes communicative sense (2) motivating children to co-operate, (3) choosing a between-/within-subjects design, (4) the use of novel items (e.g., novel verbs), (5) fillers, (6) blocked, counterbalanced and random presentation, (7) the appropriate number of trials and participants, (8) drop-out rates (9) the importance of control conditions, (10) choosing a sensitive dependent measure (11) classification of responses, and (12) using an appropriate statistical test. WIREs Cogn Sci 2013, 4:149-168. doi: 10.1002/wcs.1215 For further resources related to this article, please visit the WIREs website. The authors declare no conflict of interest. Copyright © 2013 John Wiley & Sons, Ltd.

  1. The Yugoslavia Prospective Study of environmental lead exposure.

    PubMed Central

    Factor-Litvak, P; Wasserman, G; Kline, J K; Graziano, J

    1999-01-01

    The Yugoslavia Prospective Study of environmental lead exposure has studied the associations between exposure to lead and pregnancy outcomes; childhood neuropsychological, behavioral, and physical development; and hematologic, renal, and cardiovascular function. The cohort comprises 577 children born to women recruited at midpregnancy in two towns in Kosovo, Yugoslavia; one town is the site of a lead smelter, refinery, and battery plant and the other is 25 miles away and relatively unexposed. A sample of these children has been followed at 6-month intervals through 7.5 years of age. Blood lead concentrations ranged from 1 to 70 microg/dl. Exposure to lead was not associated with adverse pregnancy outcomes. Exposure was associated with modest decrements in intelligence, small increases in blood pressure, higher risks of proteinuria, small increases in behavior problems, and perturbed hematopoiesis. Only at low level exposures (i.e., <16 microg/dl) were small associations with decreased height found. We discuss methodological problems that may hinder causal interpretation of these data, namely, use of blood lead concentration as an exposure measure, confounding, and town-specific associations. We conclude that while reported associations are small, collectively they lend support to the notion that lead is a toxicant with numerous adverse health effects. Images Figure 1 PMID:9872712

  2. Study of microcirculation of the ocular ciliary body in experimental kidney disease.

    PubMed

    Obrubov, S A; Ivanova, A O; Klyuchnikov, S O; Dreval, A A; Boginskaya, O A

    2014-08-01

    We studied disorders in ciliary body microcirculation in experimental chronic glomerulonephritis with tubulointerstitial nephritis and evaluated the hemodynamic effects of low-frequency pulsed electromagnetic field in this pathology. Laser Doppler flowmetry demonstrated vasospasm with reduced nutrient blood fl ow in the ciliary body of animals with experimental chronic glomerulonephritis with tubulointerstitial nephritis. The exposure to low-frequency pulsed electromagnetic field using developed technology will lead to significant reduction of the vascular tone and improve arterial blood supply to the microcirculatory bed.

  3. Theoretical and experimental studies on the foundation theoretical and experimental studies on the foundation of mesomechanics

    NASA Astrophysics Data System (ADS)

    Chudnovsky, A.; Wu, S.

    1992-06-01

    The report summarizes a closely coupled experimental and theoretical investigation of various stages of Fracture Process: (1) accumulation of 'damage' on submicroscopical and microscopical scales leading to crack initiation; (2) slow (subcritical) crack growth and an evolution of the damage zone; (3) transition to dynamic crack growth and the catastrophic failure. The experimental part of the program is focused on the observation and quantitative characterization of damage preceding and accompanying crack initiation and growth. A special experimental setup for studying the fracture process under variable stress field is reported in Chapter 2. A leading role of crack-damage interaction in fracture process is well documented. A new formalism for solution of crack-microcrack array interaction problem and its successful implementation in the evaluation of crack layer driving forces is presented in Chapter 3. A new model of the process zone, which generalizes the well-known Dagdale-Barenblatt model is presented in Chapter 4. A new measure for material toughness and the prediction of R-curve behavior illustrate the practical application of our model. Experimental examinations of our model under various test conditions are reported in Chapters 4, 5 and 6. The development of the constitutive equations for Crack Layer evolution and their experimental examinations under stress relaxation, fatigue and creep conditions are reported in Chapters 5 and 6. An accelerated test procedure and the formulation of crack layer instability criteria as a substitution for the conventional fracture toughness parameters are also discussed in Chapter 6.

  4. Longitudinal studies of exposure to cadmium.

    PubMed Central

    Armstrong, R; Chettle, D R; Scott, M C; Blindt, M; Mason, H J

    1992-01-01

    Measurements of urinary proteins, blood and urinary cadmium, and in vivo kidney and liver cadmium have been made for a group of workers at several times between 1981 and 1990. The possibility of the introduction of measurement artifacts due to the use of different in vivo measurement systems has been assessed and is considered to be small. Changes in cadmium body burden with time have been studied in relation to kidney function. The results suggest several interesting patterns, although more data are needed to elucidate these further. They do, however, show the effectiveness of good hygiene in the workplace. PMID:1515347

  5. Experimental Study of Gas Hydrate Dynamics

    NASA Astrophysics Data System (ADS)

    Fandino, O.; Ruffine, L.

    2011-12-01

    Important quantities of methane and other gases are trapped below the seafloor and in the permafrost by an ice-like solid, called gas hydrates or clathrate hydrates. The latter is formed when water is mixing with different gases at high pressures and low temperatures. Due to a their possible use as a source of energy [1] or the problematic related to flow assurance failure in pipelines [2] the understanding of their processes of formation/destabilisation of these structures becomes a goal for many laboratories research as well as industries. In this work we present an experimental study on the stochastic behaviour of hydrate formation from a bulk phase. The method used here for the experiments was to repeat several time the same hydrate formation procedure and to notice the different from one experiment to another. A variable-volume type high-pressure apparatus with two sapphire windows was used. This device, already presented by Ruffine et al.[3], allows us to perform both kinetics and phase equilibrium measurements. Three initial pressure conditions were considered here, 5.0 MPa, 7.5 MPa and 10.0 MPa. Hydrates have been formed, then allowed to dissociate by stepwise heating. The memory effect has also been investigated after complete dissociation. It turned out that, although the thermodynamics conditions of formation and/or destabilization were reproducible. An attempt to determine the influence of pressure on the nucleation induction time will be discussed. References 1. Sum, A. K.; Koh, C. A.; Sloan, E. D., Clathrate Hydrates: From Laboratory Science to Engineering Practice. Industrial & Engineering Chemistry Research 2009, 48, 7457-7465. 2. Sloan, E. D., A changing hydrate paradigm-from apprehension to avoidance to risk management. Fluid Phase Equilibria 2005, 228, 67-74. 3. Ruffine, L.; Donval, J. P.; Charlou, J. L.; Cremière, A.; Zehnder, B. H., Experimental study of gas hydrate formation and destabilisation using a novel high-pressure apparatus. Marine

  6. 40 CFR 159.170 - Human epidemiological and exposure studies.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... studies. 159.170 Section 159.170 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Information § 159.170 Human epidemiological and exposure studies. Information must be submitted which concerns any study that a person described in § 159.158(a) has concluded, or might reasonably conclude,...

  7. The Role of the Media in Body Image Concerns among Women: A Meta-Analysis of Experimental and Correlational Studies

    ERIC Educational Resources Information Center

    Grabe, Shelly; Ward, L. Monique; Hyde, Janet Shibley

    2008-01-01

    Research suggests that exposure to mass media depicting the thin-ideal body may be linked to body image disturbance in women. This meta-analysis examined experimental and correlational studies testing the links between media exposure to women's body dissatisfaction, internalization of the thin ideal, and eating behaviors and beliefs with a sample…

  8. The Role of the Media in Body Image Concerns among Women: A Meta-Analysis of Experimental and Correlational Studies

    ERIC Educational Resources Information Center

    Grabe, Shelly; Ward, L. Monique; Hyde, Janet Shibley

    2008-01-01

    Research suggests that exposure to mass media depicting the thin-ideal body may be linked to body image disturbance in women. This meta-analysis examined experimental and correlational studies testing the links between media exposure to women's body dissatisfaction, internalization of the thin ideal, and eating behaviors and beliefs with a sample…

  9. Experimental evaluation of the usefulness of feathers as a non-destructive biomonitor for polychlorinated biphenyls (PCBs) using silastic implants as a novel method of exposure.

    PubMed

    Van den Steen, E; Covaci, A; Jaspers, V L B; Dauwe, T; Voorspoels, S; Eens, M; Pinxten, R

    2007-02-01

    Risk assessment of pollutants requires both monitoring studies in the field and experimental exposure studies. In this study, we evaluated silastic implants as an alternative method of exposure for use in toxicological studies and at the same time evaluated the usefulness of feathers as a non-destructive biomonitor for PCBs. European starlings (Sturnus vulgaris) were exposed to different doses (including a control group) of environmentally relevant concentrations of PCB 153 during a 15-week period using silastic implants with both ends/only one end sealed. After implantation, there was a rapid and significant increase in PCB 153 blood concentration in the exposed groups. The significant differences in blood concentrations among the treatment groups show that silastic implants are useful as a method of exposure. Moreover, the ratio between the tissue concentrations of two treatment groups reflected the difference in implantation doses between these groups. There was also a clear difference in tissue concentrations among the treatment groups, although we could not test this statistically due to the small sample sizes. The slow release kinetics for a prolonged period and the relatively stable blood concentrations during the 15-week period render silastic tubes very interesting to study the effects of chronic exposure to pollutants. Our results also revealed that sealing both ends of the implant instead of only one did not significantly affect the exposure. There were strong, significant positive correlations between the blood and the tissues, which confirm the use of blood to monitor PCBs. To evaluate the usefulness of feathers as a non-destructive biomonitor for PCBs, we plucked the original and newly grown wing and tail feathers. We observed strong, significant positive correlations between the concentrations in the newly grown feathers and concentrations in the muscle, liver, brain and blood. PCB 153 concentrations in the newly grown feathers differed among the

  10. STUDY DESIGN CONSIDERATIONS FOR THE EXPOSURE COMPONENT OF THE NATIONAL CHILDREN'S STUDY

    EPA Science Inventory

    An ideal strategy for the exposure monitoring component of the planned National Children's Study (NCS) is to measure indoor and outdoor concentrations and personal exposures of children to a variety of pollutants, including ambient particulate and gaseous pollutants, biologicals,...

  11. STUDY DESIGN CONSIDERATIONS FOR THE EXPOSURE COMPONENT OF THE NATIONAL CHILDREN'S STUDY

    EPA Science Inventory

    An ideal strategy for the exposure monitoring component of the planned National Children's Study (NCS) is to measure indoor and outdoor concentrations and personal exposures of children to a variety of pollutants, including ambient particulate and gaseous pollutants, biologicals,...

  12. The Role of the Scientific Discovery Narrative in Middle School Science Education: An Experimental Study

    ERIC Educational Resources Information Center

    Arya, Diana J.; Maul, Andrew

    2012-01-01

    In an experimental study (N = 209), the authors compared the effects of exposure to typical middle-school written science content when presented in the context of the scientific discovery narrative and when presented in a more traditional nonnarrative format on 7th and 8th grade students in the United States. The development of texts was…

  13. [Silicosis hazard of silica dusts in diamond mining industry (experimental study)].

    PubMed

    Mironova, G E; Bezrukavnikova, L M; Kuz'mina, L P

    2001-01-01

    Slow progressing experimental coniosis was induced by exposure to two samples of silica dust that was obtained from diamond openwork in "Mir" quarry of Yakutia. Moderate fibrogenicity of the dusts studied results from relatively low portions of silica and from metals oxides admixtures.

  14. Experimental study of finite Larmor radius effects

    SciTech Connect

    Struve, K.W.

    1980-08-01

    Linear Z-pinches in Ar, Kr, Xe, N/sub 2/, and He are experimentally studied in regimes where strong finite Larmor radius effects could provide a significant stabilizing effect. Scaling arguments show that for deuterium such a pinch has an electron line density of order 2 x 10/sup 15//cm. For higher Z plasmas a higher line density is allowed, the exact value of which depends on the average ion charge. The pinch is formed by puffing gas axially through the cathode towards the anode of an evacuated pinch chamber. When the gas reaches the anode, the pinch bank is fired. The pinch current rises in 2 to 3 ..mu..sec to a maximum of 100 to 200 kA. The pinch bank capacitance is 900 ..mu..F, and the external inductance is 100 nH. Additionally, the bank is fused to increase dI/dt. The primary diagnostics are a framing camera, a spatially resolved Mach-Zehnder interferometer, and X-ray absorption.

  15. Experimental study of trimethyl aluminum decomposition

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi; Pan, Yang; Yang, Jiuzhong; Jiang, Zhiming; Fang, Haisheng

    2017-09-01

    Trimethyl aluminum (TMA) is an important precursor used for metal-organic chemical vapor deposition (MOCVD) of most Al-containing structures, in particular of nitride structures. The reaction mechanism of TMA with ammonia is neither clear nor certain due to its complexity. Pyrolysis of trimethyl metal is the start of series of reactions, thus significantly affecting the growth. Experimental study of TMA pyrolysis, however, has not yet been conducted in detail. In this paper, a reflectron time-of-flight mass spectrometer is adopted to measure the TMA decomposition from room temperature to 800 °C in a special pyrolysis furnace, activated by soft X-ray from the synchrotron radiation. The results show that generation of methyl, ethane and monomethyl aluminum (MMA) indicates the start of the pyrolysis process. In the low temperature range from 25 °C to 700 °C, the main product is dimethyl aluminum (DMA) from decomposition of TMA. For temperatures larger than 700 °C, the main products are MMA, DMA, methyl and ethane.

  16. Pulmonary emphysema induced by methylphenidate: experimental study.

    PubMed

    Rapello, Gabriel Victor Guimarães; Antoniolli, Andréia; Pereira, Daniel Martins; Facco, Gilberto; Pêgo-Fernandes, Paulo Manuel; Pazetti, Rogério

    2015-01-01

    Methylphenidate is the most widely used drug for treating attention deficit hyperactivity disorder. However, it has important side effects, such as abdominal pain, insomnia, anorexia and loss of appetite, and also some cases of early severe emphysema after drug abuse have been reported. Our aim was to investigate the development of pulmonary emphysema in rats that were subjected to different doses of methylphenidate. Experimental study carried out at the laboratory of a public university. Eighteen male Wistar rats were divided into three groups: control (0.9% saline solution); MP 0.8 (methylphenidate, 0.8 mg/kg); MP 1.2 (methylphenidate, 1.2 mg/kg). After 90 days of daily gavage, the animals were sacrificed and lung tissue samples were prepared for analysis on the mean alveolar diameter (Lm). The Lm was greater in MP 0.8 (47.91 ± 3.13; P < 0.01) and MP 1.2 (46.36 ± 4.39; P < 0.05) than in the control group (40.00 ± 3.48). Methylphenidate caused an increase in the alveolar diameter of rats, which was compatible with human pulmonary emphysema.

  17. [Experimental study on the Eu isotopic enrichment].

    PubMed

    Huang, Xue-ren; Zhong, Da; Mei, Gang-hua; Zhu, Xi-wen

    2002-10-01

    The polarized atomic beam has found many applications, such as in studying atomic scattering processes, producing polarized nucleus, verifying the parity principle, measuring surface parameters and enriching isotopes. In this paper, we mainly described the experiment of Eu isotope enrichment by means of magnetic deflection. According to the special inner energy level structure of Eu atom, we analyzed the theory of the polarized atomic beam and described the main experimental set-up. Using one coherent laser with the wavelength of 601.9 nm and sigma polarization, Eu153 atoms have been selectively optical pumped and polarized, so positive and negative polarized atomic beams could be produced. The polarized atomic beams have been focused and defocused after passing through the deflection by hex-magnet. Finally, some clear enrichmental signal has been obtained in way of hot-wire detection. During the process of the experiment, we carefully selected the optimized conditions, the Eu153 enrichment effect of 4% can be achieved using only one coherent laser.

  18. An experimental study on pedestrian classification.

    PubMed

    Munder, S; Gavrila, D M

    2006-11-01

    Detecting people in images is key for several important application domains in computer vision. This paper presents an in-depth experimental study on pedestrian classification; multiple feature-classifier combinations are examined with respect to their ROC performance and efficiency. We investigate global versus local and adaptive versus nonadaptive features, as exemplified by PCA coefficients, Haar wavelets, and local receptive fields (LRFs). In terms of classifiers, we consider the popular Support Vector Machines (SVMs), feed-forward neural networks, and k-nearest neighbor classifier. Experiments are performed on a large data set consisting of 4,000 pedestrian and more than 25,000 nonpedestrian (labeled) images captured in outdoor urban environments. Statistically meaningful results are obtained by analyzing performance variances caused by varying training and test sets. Furthermore, we investigate how classification performance and training sample size are correlated. Sample size is adjusted by increasing the number of manually labeled training data or by employing automatic bootstrapping or cascade techniques. Our experiments show that the novel combination of SVMs with LRF features performs best. A boosted cascade of Haar wavelets can, however, reach quite competitive results, at a fraction of computational cost. The data set used in this paper is made public, establishing a benchmark for this important problem.

  19. Playfulness and prenatal alcohol exposure: a comparative study.

    PubMed

    Pearton, Jordan Louise; Ramugondo, Elelwani; Cloete, Lizahn; Cordier, Reinie

    2014-08-01

    South Africa carries a high burden of alcohol abuse. The effects of maternal alcohol consumption during pregnancy are most pronounced in poor, rural communities. Earlier research suggests that children with prenatal alcohol exposure have poor social behaviour; however, to date, no research has investigated their playfulness. This study investigated the differences in playfulness of children with and without prenatal alcohol exposure. Grade one learners with a positive history of prenatal alcohol exposure (n = 15) and a reference group without a positive history of prenatal alcohol exposure (n = 15) were filmed engaging in free play at their schools. The Test of Playfulness was used to measure playfulness from recordings. Data were subjected to Rasch analysis to calculate interval level measure scores for each participant. The overall measure scores and individual Test of Playfulness social items were subjected to paired samples t-tests to calculate if significant differences existed between the groups. Children with prenatal alcohol exposure had a significantly lower mean overall playfulness score than the reference group (t = -2.51; d.f. = 28; P = 0.02). Children with prenatal alcohol exposure also scored significantly lower than the reference group on 5 of the 12 Test of Playfulness items related to social play. This research suggests that children with prenatal alcohol exposure are more likely to experience poorer overall quality of play, with particular deficits in social play. Considering play is a child's primary occupation, this finding becomes pertinent for occupational therapy practice, particularly in post-apartheid South Africa, where high prenatal alcohol exposure prevalence rates are couched within persistent socio-economic inequalities. © 2014 Occupational Therapy Australia.

  20. Vulnerability of welders to manganese exposure--a neuroimaging study.

    PubMed

    Long, Zaiyang; Jiang, Yue-Ming; Li, Xiang-Rong; Fadel, William; Xu, Jun; Yeh, Chien-Lin; Long, Li-Ling; Luo, Hai-Lan; Harezlak, Jaroslaw; Murdoch, James B; Zheng, Wei; Dydak, Ulrike

    2014-12-01

    Increased manganese (Mn) exposure is known to cause cognitive, psychiatric and motor deficits. Mn exposure occurs in different occupational settings, where the airborne Mn level and the size of respirable particulates may vary considerably. Recently the importance of the role of the cerebral cortex in Mn toxicity has been highlighted, especially in Mn-induced neuropsychological effects. In this study we used magnetic resonance imaging (MRI) to evaluate brain Mn accumulation using T1 signal intensity indices and to examine changes in brain iron content using T2* contrast, as well as magnetic resonance spectroscopy (MRS) to measure exposure-induced metabolite changes non-invasively in cortical and deep brain regions in Mn-exposed welders, Mn-exposed smelter workers and control factory workers with no measurable exposure to Mn. MRS data as well as T1 signal intensity indices and T2* values were acquired from the frontal cortex, posterior cingulate cortex, hippocampus, and thalamus. Smelters were exposed to higher air Mn levels and had a longer duration of exposure, which was reflected in higher Mn levels in erythrocytes and urine than in welders. Nonetheless, welders had more significant metabolic differences compared to controls than did the smelter workers, especially in the frontal cortex. T1 hyperintensities in the globus pallidus were observed in both Mn-exposed groups, but only welders showed significantly higher thalamic and hippocampal T1 hyperintensities, as well as significantly reduced T2* values in the frontal cortex. Our results indicate that (1) the cerebral cortex, in particular the frontal cortex, is clearly involved in Mn neurotoxic effects and (2) in spite of the lower air Mn levels and shorter duration of exposure, welders exhibit more extensive neuroimaging changes compared to controls than smelters, including measurable deposition of Mn in more brain areas. These results indicate that the type of exposure (particulate sizes, dust versus fume) and

  1. Experimental studies of gas-aerosol reactions

    NASA Astrophysics Data System (ADS)

    Gupta, Anand

    1991-05-01

    The aqueous phase oxidation of SO2 by H2O2 is believed to the principle mechanism for atmospheric sulfate formation in cloud droplets. However, no studies in noncloud aerosol systems have been reported. The objective is to quantify the importance of the noncloud liquid phase reactions of SO2 by H2O2 in the atmosphere. Growth rates of submicron droplets exposed to SO2 and H2O2 were measured using the tandem differential mobility analyzer (TDMA) technique (Rader and McMurry, 1986). The technique uses differential mobility analyzers (DMA's) to generate monodisperse particles and to measure particle size after the reaction. To facilitate submicron monodisperse droplet production with the DMA, a low-ion-concentration charter capable of generating singly charged particles up to 1.0 microns was developed and experimentally evaluated. The experiments were performed using dry and deliquesced (NH4)2SO4 particles with SO2 and H2O2 concentrations from 0-860 ppb and 0-150 ppb, respectively. No growth was observed for dry particles. For droplets greater than or equal to 0.3 microns, the fractional diameter growth was independent of particle size and for droplets less than or equal to 0.2 microns, it decreased as particle size decreased. The observed decrease is due to NH3 evaporation. As ammonia evaporates, droplet pH decreases causing the oxidation rate to decrease, leading to a lower growth rate. To predict the size-dependent growth rates, a theoretical model was developed using solution thermodynamics, gas/particle equilibrium, and chemical kinetics. The experimental and theoretical results are in reasonable agreement. For dry (NH4)2SO4 particles exposed to SO2, H2O2, NH3, and H2O vapor, surface reaction-controlled growth was observed. Particle growth was very sensitive to particle composition. No growth was observed for Polystyrene latex particles, whereas (NH4)2SO4 particles doped with catalysts (Fe(2+), Fe(3+), Mn(2+) and Cu(2+)) in a molar ratio of 1:500 grew slower than

  2. Experimental Studies of Gas-Aerosol Reactions

    NASA Astrophysics Data System (ADS)

    Gupta, Anand

    1991-02-01

    The aqueous phase oxidation of SO_2 by H_2O_2 is believed to be the principle mechanism for atmospheric sulfate formation in cloud droplets. However, no studies in noncloud aerosol systems have been reported. The objective of this thesis is to quantify the importance of the noncloud liquid phase reactions of SO_2 by H_2O_2 in the atmosphere. In this thesis growth rates of submicron droplets exposed to SO_2 and H_2 O_2 were measured using the tandem differential mobility analyzer (TDMA) technique (Rader and McMurry, 1986). The technique uses differential mobility analyzers (DMAs) to generate monodisperse particles and to measure particle size after the reaction. To facilitate submicron monodisperse droplet production with the DMA, a low-ion-concentration charger capable of generating singly charged particles up to 1.0 μm was developed and experimentally evaluated. The experiments were performed using dry and deliquesced (NH_4)_2SO _4 particles with SO_2 and H_2O_2 concentrations from 0-860 ppb and 0-150 ppb, respectively. No growth was observed for dry particles. For droplets >=0.3 mum, the fractional diameter growth was independent of particle size and for droplets <=0.2 mum, it decreased as particle size decreased. The observed decrease is due to NH_3 evaporation. As ammonia evaporates, droplet pH decreases causing the oxidation rate to decrease, leading to a lower growth rate. To predict the size-dependent growth rates, a theoretical model was developed using solution thermodynamics, gas/particle equilibrium and chemical kinetics. The experimental and theoretical results are in reasonable agreement. For dry (NH_4) _2SO_4 particles exposed to SO_2, H_2O _2, NH_3 and H_2O vapor, surface reaction-controlled growth was observed. Particle growth was very sensitive to particle composition. No growth was observed for Polystyrene latex particles, whereas (NH_4) _2SO_4 particles doped with catalysts (Fe^{2+} , Fe^{3+}, Mn ^{2+}, Cu^{2+ }) in a molar ratio of 1:500 grew

  3. MAOA, abuse exposure and antisocial behaviour: 30-year longitudinal study.

    PubMed

    Fergusson, David M; Boden, Joseph M; Horwood, L John; Miller, Allison L; Kennedy, Martin A

    2011-06-01

    Recent studies have raised issues concerning the replicability of gene × environment (G × E) interactions involving the monoamine oxidase A (MAOA) gene in moderating the associations between abuse or maltreatment exposure and antisocial behaviour. This study attempted to replicate the findings in this area using a 30-year longitudinal study that has strong resemblance to the original research cohort. To test the hypothesis that the presence of the low-activity MAOA genotype was associated with an increased response to abuse exposure. Participants were 398 males from the Christchurch Health and Development Study who had complete data on: MAOA promoter region variable number tandem repeat genotype; antisocial behaviour to age 30; and exposure to childhood sexual and physical abuse. Regression models were fitted to five antisocial behaviour outcomes (self-reported property offending; self-reported violent offending; convictions for property/violent offending; conduct problems; hostility) observed from age 16 to 30, using measures of childhood exposure to sexual and physical abuse. The analyses revealed consistent evidence of G × E interactions, with those having the low-activity MAOA variant and who were exposed to abuse in childhood being significantly more likely to report later offending, conduct problems and hostility. These interactions remained statistically significant after control for a range of potentially confounding factors. Findings for convictions data were somewhat weaker. The present findings add to the evidence suggesting that there is a stable G × E interaction involving MAOA, abuse exposure and antisocial behaviour across the life course.

  4. Evapotranspiration studies for protective barriers: Experimental plans

    SciTech Connect

    Link, S.O.; Waugh, W.J.

    1989-11-01

    This document describes a general theory and experimental plans for predicting evapotranspiration in support of the Protective Barrier Program. Evapotranspiration is the combined loss of water from plants and soil surfaces to the atmosphere. 45 refs., 1 fig., 4 tabs.

  5. The Seveso studies on early and long-term effects of dioxin exposure: a review.

    PubMed Central

    Bertazzi, P A; Bernucci, I; Brambilla, G; Consonni, D; Pesatori, A C

    1998-01-01

    The industrial accident that occurred in the town of Seveso, Italy, in 1976 exposed a large population to substantial amounts of relatively pure 2,3,7,8-tetrachlorodibenzo-p-dioxin. Extensive monitoring of soil levels and measurements of a limited number of human blood samples allowed classification of the exposed population into three categories, A (highest exposure), B (median exposure), and R (lowest exposure). Early health investigations including liver function, immune function, neurologic impairment, and reproductive effects yielded inconclusive results. Chloracne (nearly 200 cases with a definite exposure dependence) was the only effect established with certainty. Long-term studies were conducted using the large population living in the surrounding noncontaminated territory as reference. An excess mortality from cardiovascular and respiratory diseases was uncovered, possibly related to the psychosocial consequences of the accident in addition to the chemical contamination. An excess of diabetes cases was also found. Results of cancer incidence and mortality follow-up showed an increased occurrence of cancer of the gastrointestinal sites and of the lymphatic and hematopoietic tissue. Experimental and epidemiologic data as well as mechanistic knowledge support the hypothesis that the observed cancer excesses are associated with dioxin exposure. Results cannot be viewed as conclusive. The study is continuing in an attempt to overcome the existing limitations (few individual exposure data, short latency period, and small population size for certain cancer types) and to explore new research paths (e.g., differences in individual susceptibility). Images Figure 1 PMID:9599710

  6. Urinary levoglucosan as a biomarker of wood smoke: results of human exposure studies.

    PubMed

    Bergauff, Megan A; Ward, Tony J; Noonan, Curtis W; Migliaccio, Christopher T; Simpson, Christopher D; Evanoski, Ashley R; Palmer, Christopher P

    2010-06-01

    Urinary levoglucosan was investigated as a potential biomarker of wood smoke exposure in two different controlled experimental settings. Nine subjects were exposed to smoke from a campfire in a controlled setting, and four were exposed to smoke from an older-model wood stove. All subjects were asked to provide urine samples before and after exposure, and to wear personal particulate matter with a diameter of < or =2.5 microm (PM(2.5)) monitors during exposure. Urinary levoglucosan measurements from both studies showed no consistent response to the smoke exposure. A third experiment was conducted to assess the contribution of dietary factors to urinary levoglucosan levels. Nine subjects were asked to consume caramel and provide urine samples before and after consumption. Urinary levoglucosan levels increased within 2 h of caramel consumption and returned to pre-exposure levels within 24 h. These studies suggest that diet is a major factor in determining urinary levoglucosan levels and that recent dietary history needs to be taken into account for future work involving levoglucosan as a biomarker of wood smoke exposure.

  7. Urinary Levoglucosan as a Biomarker for Wood Smoke: Results of Human Exposure Studies

    PubMed Central

    Bergauff, Megan A.; Ward, Tony J.; Noonan, Curtis W.; Migliaccio, Christopher T.; Simpson, Christopher D.; Evanoski, Ashley R.; Palmer, Christopher P.

    2010-01-01

    Urinary levoglucosan was investigated as a potential biomarker for wood smoke exposure in two different controlled experimental settings. Nine subjects were exposed to smoke from a campfire in a controlled setting and four were exposed to smoke from an older model wood stove. All subjects were asked to provide urine samples before and after exposure, and to wear personal PM2.5 monitors during the exposure. Urinary levoglucosan measurements from both studies showed no consistent response to the smoke exposure. A third experiment was conducted to assess the contribution of dietary factors to urinary levoglucosan levels. Nine subjects were asked to consume caramel and provide urine samples before and after consumption. Urinary levoglucosan levels increased within 2 hours of caramel consumption and returned to pre-exposure levels within 24 hours. These studies suggest that diet is a major factor in determining urinary levoglucosan levels and recent dietary history needs to be taken into account for future work involving levoglucosan as a biomarker of wood smoke exposure. PMID:19707249

  8. An experimental study on microwave electron gun

    SciTech Connect

    Wang, G.; Wu, J.; Wang, Y.

    1995-12-31

    We report both the simulation and experimental results of using a ring cathode instead of the solid cathode to reduce the back bombardment effect of a thermionic cathode microwave electron gun. The result shows that the back bombardment power is decreased about 2/3 without changing the beam quality apparently which allows operation at higher repetition rate. Experimental results are compared with the simulation with good agreement.

  9. Experimental Study of Lunar and SNC Magmas

    NASA Technical Reports Server (NTRS)

    Rutherford, Malcolm J.

    1998-01-01

    The research described in this progress report involved the study of petrological, geochemical and volcanic processes that occur on the Moon and the SNC parent body, generally accepted to be Mars. The link between these studies is that they focus on two terrestrial-type parent bodies somewhat smaller than earth, and the fact that they focus on the role of volatiles in magmatic processes and on processes of magma evolution on these planets. The work on the lunar volcanic glasses has resulted in some exciting new discoveries over the years of this grant. We discovered small metal blebs initially in the Al5 green glass, and determined the significant importance of this metal in fixing the oxidation state of the parent magma (Fogel and Rutherford, 1995). More recently, we discovered a variety of metal blebs in the Al7 orange glass. Some of these Fe-Ni metal blebs were in the glass; others were in olivine phenocrysts. The importance of these metal spheres is that they fix the oxidation state of the parent magma during the eruption, and also indicate changes during the eruption (Weitz et al., 1997) They also yield important information about the composition of the gas phase present, the gas which drove the lunar fire-fountaining. One of the more exciting and controversial findings in our research over the past year has been the possible fractionation of H from D during shock (experimental) of hornblende bearing samples (Minitti et al., 1997). This research is directed at explaining some of the low H2O and high D/H observed in hydrous phases in the SNC meteorites.

  10. Experimental and computational studies of nanofluids

    NASA Astrophysics Data System (ADS)

    Vajjha, Ravikanth S.

    The goals of this dissertation were (i) to experimentally investigate the fluid dynamic and heat transfer performance of nanofluids in a circular tube, (ii) to study the influence of temperature and particle volumetric concentration of nanofluids on thermophysical properties, heat transfer and pumping power, (iii) to measure the rheological properties of various nanofluids and (iv) to investigate using a computational fluid dynamic (CFD) technique the performance of nanofluids in the flat tube of a radiator. Nanofluids are a new class of fluids prepared by dispersing nanoparticles with average sizes of less than 100 nm in traditional heat transfer fluids such as water, oil, ethylene glycol and propylene glycol. In cold regions of the world, the choice of base fluid for heat transfer applications is an ethylene glycol or propylene glycol mixed with water in different proportions. In the present research, a 60% ethylene glycol (EG) or propylene glycol (PG) and 40% water (W) by mass fluid mixture (60:40 EG/W or 60:40 PG/W) was used as a base fluid, which provides freeze protection to a very low level of temperature. Experiments were conducted to measure the convective heat transfer coefficient and pressure loss of nanofluids flowing in a circular tube in the fully developed turbulent regime. The experimental measurements were carried out for aluminum oxide (Al2O3), copper oxide (CuO) and silicon dioxide (SiO2) nanoparticles dispersed in 60:40 EG/W base fluid. Experiments revealed that the heat transfer coefficient of nanofluids showed an increase with the particle volumetric concentration. Pressure loss was also observed to increase with the nanoparticle volumetric concentration. New correlations for the Nusselt number and the friction factor were developed. The effects of temperature and particle volumetric concentration on different thermophysical properties (e.g. viscosity, thermal conductivity, specific heat and density) and subsequently on the Prandtl number

  11. Maternal exposures in the National Birth Defects Prevention Study: Time trends of selected exposures.

    PubMed

    Dawson, April L; Razzaghi, Hilda; Arth, Annelise; Canfield, Mark A; Parker, Samantha E; Reefhuis, Jennita

    2015-08-01

    Our objective was to describe time trends in selected pregnancy exposures in the National Birth Defects Prevention Study (NBDPS). We analyzed data from the NBDPS, a multi-site case-control study of major birth defects, for mothers of live-born infants without birth defects (controls), with an expected date of delivery (EDD) from 1998 to 2011. Mothers from the 10 participating centers across the United States were interviewed by phone between 6 weeks and 2 years after the EDD. We focused on maternal race/ethnicity and five maternal risk factors: obesity, use of folic acid-containing multivitamins, opioid analgesics, selective serotonin reuptake inhibitors, and loratadine because of their prevalence of use and some reports of associations with major birth defects. Prevalence time trends were examined using the Kendall's τβ test statistic. The exposure trend analysis included 11,724 control mothers with EDDs from 1998 to 2011. We observed a significant increase in obesity prevalence among control mothers, as well as use of selective serotonin reuptake inhibitors and loratadine. We also observed an increase in periconceptional use of folic acid-containing multivitamins. Some of the time trends varied by race/ethnicity. No remarkable trend in the overall use of opioid analgesics was observed. The racial/ethnic distribution of mothers changed slightly during the study period. Long-term, population-based case-control studies continue to be an effective way to assess exposure-birth defects associations and provide guidance to health care providers. However, investigators examining rare outcomes covering many years of data collection need to be cognizant of time trends in exposures. © 2015 Wiley Periodicals, Inc.

  12. Maternal exposures in the National Birth Defects Prevention Study: time trends of selected exposures

    PubMed Central

    Dawson, April L.; Razzaghi, Hilda; Arth, Annelise; Canfield, Mark A.; Parker, Samantha E.; Reefhuis, Jennita

    2015-01-01

    Background Our objective was to describe time trends in selected pregnancy exposures in the National Birth Defects Prevention Study (NBDPS). Methods We analyzed data from the NBDPS, a multi-site case-control study of major birth defects, for mothers of live-born infants without birth defects (controls), with an expected date of delivery (EDD) from 1998 –2011. Mothers from the 10 participating centers across the United States were interviewed by phone between six weeks and two years after the EDD. We focused on maternal race/ethnicity and five maternal risk factors: obesity, use of folic acid-containing multivitamins, opioid analgesics, selective serotonin reuptake inhibitors (SSRIs), and loratadine because of their prevalence of use and some reports of associations with major birth defects. Prevalence time trends were examined using the Kendall’s τβ test statistic. Results The exposure trend analysis included 11,724 control mothers with EDDs from 1998–2011. We observed a significant increase in obesity prevalence among control mothers, as well as use of SSRIs and loratadine. We also observed an increase in periconceptional use of folic acid-containing multivitamins. Some of the time trends varied by race/ethnicity. No remarkable trend in the overall use of opioid analgesics was observed. The racial/ethnic distribution of mothers changed slightly during the study period. Conclusions Long-term, population-based case-control studies continue to be an effective way to assess exposure-birth defects associations and provide guidance to health care providers. However, investigators examining rare outcomes covering many years of data collection need to be cognizant of time trends in exposures. PMID:25884728

  13. Scenarios Approach to the Electromagnetic Exposure: The Case Study of a Train Compartment

    PubMed Central

    Paffi, A.; Apollonio, F.; Pinto, R.; Liberti, M.

    2015-01-01

    Previous studies identified the train compartment as the place where people can experience the highest exposure levels (still below the international guideline limits) to electromagnetic fields in the radiofrequency range. Here a possible scenario of a train compartment has been reproduced and characterized, both numerically and experimentally. A good agreement between the simulated electric field distributions and measurements has been found. Results indicate that the higher values of exposure in specific positions inside the train compartment depend on the number of active cell phones, the bad coverage condition, the cell orientation, and the presence of metallic walls. This study shows that the proposed approach, based on the scenarios characterization, may efficiently support the assessment of the individual electromagnetic exposure. PMID:25802868

  14. Animal mortality resulting from uniform exposures to photon radiations: Calculated LD/sub 50/s and a compilation of experimental data

    SciTech Connect

    Jones, T.D.; Morris, M.D.; Wells, S.M.; Young, R.W.

    1986-12-01

    Studies conducted during the 1950s and 1960s of radiation-induced mortality to diverse animal species under various exposure protocols were compiled into a mortality data base. Some 24 variables were extracted and recomputed from each of the published studies, which were collected from a variety of available sources, primarily journal articles. Two features of this compilation effort are (1) an attempt to give an estimate of the uniform dose received by the bone marrow in each treatment so that interspecies differences due to body size were minimized and (2) a recomputation of the LD/sub 50/ where sufficient experimental data are available. Exposure rates varied in magnitude from about 10/sup -2/ to 10/sup 3/ R/min. This report describes the data base, the sources of data, and the data-handling techniques; presents a bibliography of studies compiled; and tabulates data from each study. 103 refs., 44 tabs.

  15. Experimental exposure of rats to methylene chloride at varying controlled barometric altitudes

    SciTech Connect

    Lillquist, D.R.

    1990-01-01

    This study investigated combined effects of three methylene chloride (MC) volume/volume concentrations (0,50, and 500 ppm) at three controlled barometric altitudes (760, 640, and 560 torr). This provided a three by three study design. For each scenario, three altitude acclimated (6 days) adult male rats were studied for eight hours in a nose-only inhalation chamber. Blood (0.35 mL) was drawn from the cannulated left carotid artery of each rat at 0, 0.5, 1, 2, 4, and 8 hours and hematocrit, pO[sub 2], pCO[sub 2], pH , total hemoglobin (Hb) and carboxyhemoglobin (CHb) were measured. Time, MC concentration and altitude had significant effects on CHb production. CHb increased with increasing MC concentration over time. Increased barometric altitude (reduced partial pressure of MC vapor at altitude for equal ppm concentrations) resulted in lower blood CHb levels. A statistical model was derived to explain variation in CHb levels for these three independent variables (r = 0.983). The data were applied to an equation assessing the impact of altitude, MC concentration and time on the potential oxygen carrying capacity (POCC) of blood. The POCC of HB in the blood was calculated using blood Hb, CHb levels, Hb oxygen saturation (based on the blood pO[sub 2] and the oxygen dissociation curve for rats), and oxygen binding potential of Hb. It was determined for the altitudes and MC concentrations used, polycythemia associated with increased altitude had a greater impact on POCC than decreased pO[sub 2]. A regression equation was derived modeling variation in POCC of blood for the three independent variables (r = 0.995). This study demonstrated that altitude affects airborne ppm MC concentrations. This ultimately impacts CHb levels and oxygen carrying capacity of the blood. These finding indicate that occupationally acceptable ppm MC exposure levels at altitude do need barometric pressure correction.

  16. Investing in Prospective Cohorts for Etiologic Study of Occupational Exposures

    EPA Science Inventory

    Prospective cohorts have played a major role in understanding the role of diet, physical activity, medical conditions, and genes in the development of many diseases, but have not been widely used in the study of occupational exposures. Studies in agriculture are an exception. W...

  17. Investing in Prospective Cohorts for Etiologic Study of Occupational Exposures

    EPA Science Inventory

    Prospective cohorts have played a major role in understanding the role of diet, physical activity, medical conditions, and genes in the development of many diseases, but have not been widely used in the study of occupational exposures. Studies in agriculture are an exception. W...

  18. Brood patches of American kestrels altered by experimental exposure to PCBs.

    PubMed

    Fisher, Sheri A; Bortolotti, Gary R; Fernie, Kim J; Bird, David M; Smits, Judit E

    2006-09-01

    Captive breeding (n = 25 pairs) and nonbreeding (n = 25) American kestrels were exposed to a mixture of polychlorinated biphenyls (PCBs) (Aroclor 1248:1254:1260) through their diet of day-old cockerels. Kestrels ingested approximately 7 mg/kg body weight each day of PCBs, and this dosage resulted in environmentally relevant total PCB residues in eggs (geometric mean of 34.1 microg/g). An equal number of unexposed birds served as controls. Bare areas of skin known as brood patches function during incubation to warm eggs; therefore, brood patch size could potentially influence hatching success, or patches may be a confounding factor in the relationship between poor incubation behavior and hatching failure observed in birds in toxicological studies. Exposure to PCBs altered the size of brood patches in American kestrels. PCB-exposed male and female nonbreeders had two of three brood patches that were larger than those of control nonbreeders. Breeding males exposed to PCBs had smaller patches than controls, whereas PCB-exposed female kestrels had one larger and one smaller patch than controls. Patch sizes were not related to total PCB residue levels in eggs of exposed birds. Brood patches were not related to various incubation behaviors or hatching success in either control or PCB-exposed kestrels.

  19. Experimental evidence for the possible exposure of workers to hexachlorobenzene by skin contamination.

    PubMed Central

    Koizumi, A

    1991-01-01

    The absorption of dermally applied 14C-hexachlorobenzene (14C-HCB; ranging from 2.5 to 2.6 mg/4 cm2) was investigated in the rat. The absorbed portion increased from 1% at six hours to 9.7% at 72 hours after dosing and blood concentrations of 14C increased linearly with time. The rate of absorption was 3.51 (SD 0.81) micrograms/h/4 cm2 and the absorption constant 1.40 (SD 0.33) x 10(-3)/h. Washing with soap at six hours after dosing removed 34% of the dose and decreased absorption by 50% in the next 66 hours. Finally, the compartment model, which incorporated the absorption constant, simulated the time profile of HCB kinetics in blood, and that of cumulative excretion in rats. The model with the absorption constant for the rat was then scaled up for a 70 kg worker, whose exposure was assumed to be exclusively dermal. A rough dermal contamination, which corresponds to the tentative HCB critical blood concentration of 200 ppb, was calculated for different simulated biological half lives. It was 18.2 mg for 100, 5.02 mg for 365, and 2.56 mg for 730 day half lives. The study indicates that dermal contamination can be a source of HCB body burden, and that personal hygiene, such as taking a shower and hand washing is likely to have a profound influence on the body burden of HCB. PMID:1911405

  20. Exposure to aripiprazole during embryogenesis: a prospective multicenter cohort study.

    PubMed

    Bellet, Florelle; Beyens, Marie-Noëlle; Bernard, Nathalie; Beghin, Delphine; Elefant, Elisabeth; Vial, Thierry

    2015-04-01

    The main purpose of this study was to evaluate the risk of major malformations after aripiprazole exposure during the embryonic period. The secondary purposes were to assess the risk of miscarriage, prematurity, fetal growth retardation and maternal complications and to describe possible neonatal adverse effects. We conducted a cohort study using data prospectively collected by the French Pharmacovigilance Centres participating to the Terappel program and the Centre de Référence sur les Agents Tératogènes between 2004 and 2011. The exposed group consisted of pregnant women exposed to aripiprazole during embryogenesis, and the unexposed group consisted of pregnant women without exposure or exposed to non-teratogenic agents. Two unexposed patients, matched for age and gestational age at call, were randomly selected for each exposed patient. Eighty-six patients were included in the exposed group and 172 in the unexposed group. Exposure to aripiprazole was not significantly associated with an increased rate of major malformations (OR 2.30, 95%CI 0.32-16.7) or miscarriage (1.66, 0.63-4.38) or gestational diabetes (1.15, 0.33-4.04) compared to non-exposure. The study revealed significantly increased rates of prematurity (OR 2.57, 95%CI 1.06-6.27) and fetal growth retardation (2.97, 1.23-7.16) in exposed newborns, difficult to interpret because of the short duration of maternal exposure. Two cases of neonatal complications were reported among the 19 newborns exposed to aripiprazole near delivery. This study failed to demonstrate a significant association between aripiprazole exposure during the embryonic period and major malformations. More powerful prospective studies are required to clarify the reproductive safety profile of aripiprazole. Copyright © 2015 John Wiley & Sons, Ltd.

  1. The effects of safety-seeking behavior and guided threat reappraisal on fear reduction during exposure: an experimental investigation.

    PubMed

    Sloan, Tracy; Telch, Michael J

    2002-03-01

    We examined the effects of safety-seeking behavior and guided threat focus and reappraisal on fear reduction during exposure. Participants (N=46) displaying marked claustrophobic fear were randomized to one of three 30-min exposure conditions: (a) guided threat focus and reappraisal; (b) safety-behavior utilization; or (c) exposure only control. Tripartite outcome assessments during a behavioral approach test, along with measures of suffocation and restriction fears were obtained at pre- and post-treatment, and at a 2-week follow-up. Treatment process measures were collected throughout treatment and consisted of indices of fear activation; within and between-trial fear habituation; and suffocation and entrapment expectancies. Measures of safety behavior utilization and attentional focus were also collected to assess the integrity of the experimental manipulations. Consistent with prediction, those encouraged to utilize safety-behaviors during exposure showed significantly more fear at post-treatment and follow-up relative to those encouraged to focus and reevaluate their core threat(s) during exposure. Moreover, growth curve analyses of treatment process data analyses revealed that safety-behavior utilization exerted a detrimental effect on between-trial habituation; whereas guided threat reappraisal enhanced between-trial habituation.

  2. Exposure Assessment in the National Children’s Study: Introduction

    PubMed Central

    Needham, Larry L.; Özkaynak, Halûk; Whyatt, Robin M.; Barr, Dana B.; Wang, Richard Y.; Naeher, Luke; Akland, Gerry; Bahadori, Tina; Bradman, Asa; Fortmann, Roy; Liu, L-J. Sally; Morandi, Maria; O’Rourke, Mary Kay; Thomas, Kent; Quackenboss, James; Ryan, P. Barry; Zartarian, Valerie

    2005-01-01

    The science of exposure assessment is relatively new and evolving rapidly with the advancement of sophisticated methods for specific measurements at the picogram per gram level or lower in a variety of environmental and biologic matrices. Without this measurement capability, environmental health studies rely on questionnaires or other indirect means as the primary method to assess individual exposures. Although we use indirect methods, they are seldom used as stand-alone tools. Analyses of environmental and biologic samples have allowed us to get more precise data on exposure pathways, from sources to concentrations, to routes, to exposure, to doses. They also often allow a better estimation of the absorbed dose and its relation to potential adverse health outcomes in individuals and in populations. Here, we make note of various environmental agents and how best to assess exposure to them in the National Children’s Study—a longitudinal epidemiologic study of children’s health. Criteria for the analytical method of choice are discussed with particular emphasis on the need for long-term quality control and quality assurance measures. PMID:16079082

  3. Daily personal exposure to black carbon: A pilot study

    NASA Astrophysics Data System (ADS)

    Williams, Ryan D.; Knibbs, Luke D.

    2016-05-01

    Continuous personal monitoring is the benchmark for air pollution exposure assessment. Black carbon (BC) is a strong marker of primary combustion like vehicle and biomass emissions. There have been few studies that quantified daily personal BC exposure and the contribution that different microenvironments make to it. In this pilot study, we used a portable aethalometer to measure BC concentrations in an individual's breathing zone at 30-s intervals while he performed his usual daily activities. We used a GPS and time-activity diary to track where he spent his time. We performed twenty 24-h measurements, and observed an arithmetic mean daily exposure concentration of 603 ng/m3. We estimated that changing commute modes from bus to train reduced the 24-h mean BC exposure concentration by 29%. Switching from open windows to closed windows and recirculated air in a car led to a reduction of 32%. Living in a home without a wood-fired heater caused a reduction of 50% compared with a wood-heated home. Our preliminary findings highlight the potential utility of simple approaches to reduce a person's daily BC exposure.

  4. Pulmonary complications of mustard gas exposure: a study on cadavers.

    PubMed

    Taghaddosinejad, Fakhreddin; Fayyaz, Amir Farshid; Behnoush, Behnam

    2011-01-01

    Sulfur mustard gas is one of the chemical warfare gases that roughly about 45000 soldiers continue to suffer long-lasting consequences of exposure during the Iran-Iraq war between 1980 and 1988. According to the common pulmonary lesions due to this gas exposure, we studied gross and microscopic pulmonary lesions in cadavers and also assessed the main causes of mortality caused by mustard gas exposure. A case-series study was performed on hospital record files of 100 cadavers that were exposed with documented sulfur mustard gas during the Iran-Iraq war from 1979 to 1988 and autopsied in legal medicine organization In Tehran between 2005 and 2007 and gross and microscopic pathological findings of autopsied organs such as hematological, pulmonary, hepatic, and renal changes were evaluated. All cases were male with the mean age of 43 years. The time interval between the gas exposure and death was almost 20years. The most frequent pulmonary complication was chronic bronchitis in 81% of autopsied cadavers. Other pulmonary findings were progressive pulmonary fibrosis (9%), pulmonary infections and tuberculosis (29%), malignant cellular infiltration (4%), and aspergilloma (1%). According to the chronic progressive lesions caused by mustard gas exposure such as pulmonary lesions and also its high mortality rate, suitable programming for protection of the gas exposed persons and prohibiting chemical warfare are recommended.

  5. [Cellular changes in the paraurethral zone of the experimental animals in exposure to collost gel].

    PubMed

    Loran, O B; Siniakova, L A; shishlo, V K; Korolev, P V

    2012-01-01

    An experimental trial of the collagen gel collost was made on Wistar white female rats aged 68 and 30-36 months. 7 and 15% collost gel (the first Russian collagen gel produced from cattle skin) was implanted in paraurethral region of the animals. The connective tissue cells in the zone of collost gel injection was studied histologically, immunohistochemically, electron microscopically. The examinations revealed differences in the content of the connective tissue in the injection zone depending on a collagen concentration and the age of the animal. The findings suggest that 15% collost gel implantation in the form of a paraurethral injection may be effective in females suffering from stress urinary incontinence for narrowing urethral lumen and preventing spontaneous voiding in response to a rise of intraabdominal pressure.

  6. Exposure Assessment Issues in Epidemiology Studies of Phthalates

    PubMed Central

    Johns, Lauren E.; Cooper, Glinda S.; Galizia, Audrey; Meeker, John D.

    2015-01-01

    Purpose The purpose of this paper is to review exposure assessment issues that need to be addressed in designing and interpreting epidemiology studies of phthalates, a class of chemicals commonly used in consumer and personal care products. Specific issues include population trends in exposure, temporal reliability of a urinary metabolite measurement, and how well a single urine sample may represent longer-term exposure. The focus of this review is on seven specific phthalates: diethyl phthalate (DEP); di-n-butyl phthalate (DBP); diisobutyl phthalate (DiBP); butyl benzyl phthalate (BBzP); di(2-ethylhexyl) phthalate (DEHP); diisononyl phthalate (DiNP); and diisodecyl phthalate (DiDP). Methods Comprehensive literature search using multiple search strategies Results Since 2001, declines in population exposure to DEP, BBzP, DBP, and DEHP have been reported in the United States and Germany, but DEHP exposure has increased in China. Although the half-lives of various phthalate metabolites are relatively short (3 to 18 hours), the intraclass correlation coefficients (ICCs) for phthalate metabolites, based on spot and first morning urine samples collected over a week to several months, range from weak to moderate, with a tendency toward higher ICCs (greater temporal stability) for metabolites of the shorter-chained (DEP, DBP, DiBP and BBzP, ICCs generally 0.3 to 0.6) compared with those of the longer-chained (DEHP, DiNP, DiDP, ICCs generally 0.1 to 0.3) phthalates. Additional research on optimal approaches to addressing the issue of urine dilution in studies of associations between biomarkers and different type of health effects is needed. Conclusions In conclusion, the measurement of urinary metabolite concentrations in urine could serve as a valuable approach to estimating exposure to phthalates in environmental epidemiology studies. Careful consideration of the strengths and limitations of this approach when interpreting study results is required. PMID:26313703

  7. Computatonal and experimental study of laminar flames

    SciTech Connect

    Smooke, M.D.; Long, M.B.

    1993-12-01

    This research has centered on an investigation of the effects of complex chemistry and detailed transport on the structure and extinction of hydrocarbon flames in counterflow, cylindrical and coflowing axisymmetric configurations. The authors have pursued both computational and experimental aspects of the research in parallel. The computational work has focused on the application of accurate and efficient numerical methods for the solution of the one and two-dimensional nonlinear boundary value problems describing the various reacting systems. Detailed experimental measurements were performed on axisymmetric coflow flames using two-dimensional imaging techniques. In particular, spontaneous Raman scattering and laser induced fluorescence were used to measure the temperature, major and minor species profiles.

  8. Experimental study of uncentralized squeeze film dampers

    NASA Technical Reports Server (NTRS)

    Quinn, R. D.

    1983-01-01

    The vibration response of a rotor system supported by a squeeze film damper (SFD) was experimentally investigated in order to provide experimental data in support of the Rotor/Stator Interactive Finite Element theoretical development. Part of the investigation required the designing and building of a rotor/SFD system that could operate with or without end seals in order to accommodate different SFD lengths. SFD variables investigated included clearance, eccentricity mass, fluid pressure, and viscosity and temperature. The results show inlet pressure, viscosity and clearance have significant influence on the damper performance and accompanying rotor response.

  9. Study of gaseous benzene effects upon A549 lung epithelial cells using a novel exposure system.

    PubMed

    Mascelloni, Massimiliano; Delgado-Saborit, Juana Maria; Hodges, Nikolas J; Harrison, Roy M

    2015-08-19

    Volatile organic compounds (VOCs) are ubiquitous pollutants known to be present in both indoor and outdoor air arising from various sources. Indoor exposure has increasingly become a major cause of concern due to the effects that such pollutants can have on health. Benzene, along with toluene, is one of the main components of the VOC mixture and is a known carcinogen due to its genotoxic effects. The aim of this study was to test the feasibility of an in vitro model to study the short-term effects of exposure of lung cells to airborne benzene. We studied the effects of exposure on DNA and the production of reactive oxygen species (ROS) in A549 cells, exposed to various concentrations of benzene (0.03; 0.1; 0.3 ppm) in gaseous form using a custom designed cell exposure chamber. Results showed a concentration-dependent increase of DNA breaks and an increase of ROS production, confirming the feasibility of the experimental procedure and validating the model for further in vitro studies of exposure to other VOCs.

  10. Biomass thermochemical gasification: Experimental studies and modeling

    NASA Astrophysics Data System (ADS)

    Kumar, Ajay

    The overall goals of this research were to study the biomass thermochemical gasification using experimental and modeling techniques, and to evaluate the cost of industrial gas production and combined heat and power generation. This dissertation includes an extensive review of progresses in biomass thermochemical gasification. Product gases from biomass gasification can be converted to biopower, biofuels and chemicals. However, for its viable commercial applications, the study summarizes the technical challenges in the gasification and downstream processing of product gas. Corn stover and dried distillers grains with solubles (DDGS), a non-fermentable byproduct of ethanol production, were used as the biomass feedstocks. One of the objectives was to determine selected physical and chemical properties of corn stover related to thermochemical conversion. The parameters of the reaction kinetics for weight loss were obtained. The next objective was to investigate the effects of temperature, steam to biomass ratio and equivalence ratio on gas composition and efficiencies. DDGS gasification was performed on a lab-scale fluidized-bed gasifier with steam and air as fluidizing and oxidizing agents. Increasing the temperature resulted in increases in hydrogen and methane contents and efficiencies. A model was developed to simulate the performance of a lab-scale gasifier using Aspen Plus(TM) software. Mass balance, energy balance and minimization of Gibbs free energy were applied for the gasification to determine the product gas composition. The final objective was to optimize the process by maximizing the net energy efficiency, and to estimate the cost of industrial gas, and combined heat and power (CHP) at a biomass feedrate of 2000 kg/h. The selling price of gas was estimated to be 11.49/GJ for corn stover, and 13.08/GJ for DDGS. For CHP generation, the electrical and net efficiencies were 37 and 86%, respectively for corn stover, and 34 and 78%, respectively for DDGS. For

  11. Assessment of a Pesticide Exposure Intensity Algorithm in the Agricultural Health Study

    EPA Science Inventory

    The accuracy of the exposure assessment is a critical factor in epidemiological investigations of pesticide exposures and health in agricultural populations. However, few studies have been conducted to evaluate questionnaire-based exposure metrics. The Agricultural Health Study...

  12. Assessment of a Pesticide Exposure Intensity Algorithm in the Agricultural Health Study

    EPA Science Inventory

    The accuracy of the exposure assessment is a critical factor in epidemiological investigations of pesticide exposures and health in agricultural populations. However, few studies have been conducted to evaluate questionnaire-based exposure metrics. The Agricultural Health Study...

  13. Marine molluscs in environmental monitoring. II. Experimental exposure to selected pollutants

    NASA Astrophysics Data System (ADS)

    Bresler, Vladimir; Mokady, Ofer; Fishelson, Lev; Feldstein, Tamar; Abelson, Avigdor

    2003-10-01

    In an effort to establish biomonitoring programmes for routine and emergency monitoring of littoral marine habitats, organismal responses are examined in two ways: firstly, in controlled, laboratory studies, where the response may be accurately characterized; secondly, in field-collected specimens, with the hope of obtaining evidence regarding disturbances such as the ones caused by anthropogenic pollution. In many cases, there is a gap between the two types of studies, and different species and experimental and/or analytical procedures are used. In a series of recent studies, we have examined responses of field-collected molluscs, and interpreted our findings with respect to pollution. Here, we report a complementary study, in which molluscs collected from reference and polluted sites were exposed to cadmium or DDT under controlled laboratory conditions. Using fluorescent probes and microfluorometry, we examined the effect of these pollutants on paracellular permeability, lysosomal stability and metabolic status of mitochondria. Our findings indicate that molluscs from polluted sites are less affected, showing significantly smaller alterations in all examined parameters. These findings are in line with previous results showing higher levels of activity of cellular defence mechanisms in molluscs collected from polluted sites. Taken together, the results may be used to establish a reliable biomonitoring system. The sensitivity of the suggested methodology is also expected to qualify such a system for early warning.

  14. A newly designed experimental system for exposure of mammalian cells to extremely low frequency magnetic fields.

    PubMed

    Miyakoshi, J; Ohtsu, S; Tatsumi-Miyajima, J; Takebe, H

    1994-03-01

    To examine the biological effects of extremely low frequency magnetic field (ELFMF), we have designed and manufactured a new equipment for long-term and high-density exposure of cells to ELFMF. The ELFMF exposure system consists of a generator of magnets with a built-in CO2 incubator, an alternating current (AC) power supply, a gas compressor and a thermocontroller for the incubator, and a cooling unit for the magnets. The CO2 incubator made of acrylic resin is inserted into the inner-space of the silicon steel strip-cores. In this system, the temperature of the incubator is maintained at 37 +/- 0.5 degrees C. The maximum magnetic flux density on the exposure area of the incubator is 500 mT (T; tesla) at a current of 556 Arms (rms; root mean square) at 50 Hz. The long-term (up to 120 hr) exposure of 400 mT ELFMF did not affect the growth of both HL60RG and CCRF-CEM cells originated from human leukemia. The post-X-irradiation exposure of 400 mT ELFMF for 2 hr also did not affect the radiation sensitivity of GM0637 and TAT2SF cells originated from a normal human and an ataxia telangiectasia patient.

  15. Aircrew exposure monitoring: results of 2001 to 2003 studies.

    PubMed

    Spurný, F; Turek, K; Vlcek, B; Dachev, Ts

    2004-01-01

    Aircrew exposure represents one of the recent subjects of occupational individual dosimetry. Since 1991 many new results have been found; there is however a need to gather further data on this exposure and its variation with geomagnetic position, solar activity and flight route parameters. Since 2001, many individual and six long-term monitoring programmes have been conducted onboard aircraft of Czech Airlines (CSA). In these programmes, a Si-diode spectrometer was fixed in an aircraft. Together with it, passive dosemeters thermoluminescent detector, track-etch based neutron dosemeter linear energy transfer and spectrometer) were exposed. More than 700 regular commercial flights were monitored in this manner. CSA supplied us also with full navigation data, which allowed us to calculate the exposure levels using EPCARD 3.2 and CARI6 codes. Direct experimental readings obtained with the detectors mentioned above were interpreted on the basis of calibrations in on-Earth reference fields and compared with calculated data. A satisfactory correlation between all sets of data was observed.

  16. Study of reference waves in single-exposure generalized phase-shifting digital holography.

    PubMed

    Imbe, Masatoshi; Nomura, Takanori

    2013-06-20

    The appropriate reference wave in single-exposure phase-shifting digital holography using a random-complex-amplitude encoded reference wave is experimentally investigated. Although the reference wave is generalized, the quality of reconstructed images depends on it. Furthermore, when the reference wave satisfies a certain condition, reconstructed images cannot be obtained in this method. After the certain condition is presented, the appropriate condition is studied using a speckle property. Experimental results are given to investigate the relations between the quality of reconstructed images and the sizes of speckles of the reference waves. The results prove that the appropriate reference wave exists in this method.

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

    PubMed

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

    1984-12-01

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

  18. Design of the Experimental Exposure Conditions to Simulate Ionizing Radiation Effects on Candidate Replacement Materials for the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Smith, L. Montgomery

    1998-01-01

    In this effort, experimental exposure times for monoenergetic electrons and protons were determined to simulate the space radiation environment effects on Teflon components of the Hubble Space Telescope. Although the energy range of the available laboratory particle accelerators was limited, optimal exposure times for 50 keV, 220 keV, 350 keV, and 500 KeV electrons were calculated that produced a dose-versus-depth profile that approximated the full spectrum profile, and were realizable with existing equipment. For the case of proton exposure, the limited energy range of the laboratory accelerator restricted simulation of the dose to a depth of .5 mil. Also, while optimal exposure times were found for 200 keV, 500 keV and 700 keV protons that simulated the full spectrum dose-versus-depth profile to this depth, they were of such short duration that the existing laboratory could not be controlled to within the required accuracy. In addition to the obvious experimental issues, other areas exist in which the analytical work could be advanced. Improved computer codes for the dose prediction- along with improved methodology for data input and output- would accelerate and make more accurate the calculational aspects. This is particularly true in the case of proton fluxes where a paucity of available predictive software appears to exist. The dated nature of many of the existing Monte Carlo particle/radiation transport codes raises the issue as to whether existing codes are sufficient for this type of analysis. Other areas that would result in greater fidelity of laboratory exposure effects to the space environment is the use of a larger number of monoenergetic particle fluxes and improved optimization algorithms to determine the weighting values.

  19. Assessment of carcinogenic risk from personal exposure to benzo(a)pyrene in the Total Human Environmental Exposure Study (THEES)

    SciTech Connect

    Butler, J.P.; Post, G.B.; Lioy, P.J.; Waldman, J.M.; Greenberg, A. )

    1993-07-01

    The Total Human Environmental Exposure Study (THEES) was an investigation of multimedia exposure to the ubiquitous environmental carcinogen, benzo(a)pyrene (BaP). The three-phase study was conducted in Phillipsburg, New Jersey and involved the participation of 14-15 individuals (8-10 homes) during each 14-day monitoring period. Microenvironmental sampling of air, food, water and soil indicated that environmental exposure to BaP was primarily through air and food. Exposure and risk estimates were, therefore, based on the results of personal monitoring of breathing zone air and prepared food samples. Based on a comparison of the range and magnitude of inhalation and dietary BaP exposures, food ingestion was clearly the predominant exposure to pathway. The relative contributions of other potential sources of community exposure to BaP (e.g., soil and drinking water ingestion) were also assessed. The excess cancer risk estimates for food ingestion were consistently greater than those for personal air, reflecting both the predominantly higher BaP exposures through the diet and the higher carcinogenic potency value for oral exposure. Overall, the total lifetime risk from personal exposure to BaP for nonsmokers in the community was estimated at 10(-5). In identifying risk reduction options, it is important to account for the observation that personal activities, lifestyle, and diet strongly influenced individual exposures to BaP.

  20. Mechanisms of methylmercury-induced neurotoxicity: evidence from experimental studies

    PubMed Central

    Farina, Marcelo; Rocha, João B. T.; Aschner, Michael

    2011-01-01

    Neurological disorders are common, costly, and can cause enduring disability. Although mostly unknown, a few environmental toxicants are recognized causes of neurological disorders and subclinical brain dysfunction. One of the best known neurotoxins is methylmercury (MeHg), a ubiquitous environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. In the aquatic environment, MeHg is accumulated in fish, which represent a major source of human exposure. Although several episodes of MeHg poisoning have contributed to the understanding of the clinical symptoms and histological changes elicited by this neurotoxicant in humans, experimental studies have been pivotal in elucidating the molecular mechanisms that mediate MeHg-induced neurotoxicity. The objective of this mini-review is to summarize data from experimental studies on molecular mechanisms of MeHg-induced neurotoxicity. While the full picture has yet to be unmasked, in vitro approaches based on cultured cells, isolated mitochondria and tissue slices, as well as in vivo studies based mainly on the use of rodents, point to impairment in intracellular calcium homeostasis, alteration of glutamate homeostasis and oxidative stress as important events in MeHg-induced neurotoxicity. The potential relationship among these events is discussed, with particular emphasis on the neurotoxic cycle triggered by MeHg-induced excitotoxicity and oxidative stress. The particular sensitivity of the developing brain to MeHg toxicity, the critical role of selenoproteins and the potential protective role of selenocompounds are also discussed. These concepts provide the biochemical bases to the understanding of MeHg neurotoxicity, contributing to the discovery of endogenous and exogenous molecules that counteract such toxicity and provide efficacious means for ablating this vicious cycle. PMID:21683713

  1. The University of Michigan Dioxin Exposure Study: Methods for an Environmental Exposure Study of Polychlorinated Dioxins, Furans, and Biphenyls

    PubMed Central

    Garabrant, David H.; Franzblau, Alfred; Lepkowski, James; Gillespie, Brenda W.; Adriaens, Peter; Demond, Avery; Ward, Barbara; LaDronka, Kathy; Hedgeman, Elizabeth; Knutson, Kristine; Zwica, Lynn; Olson, Kristen; Towey, Timothy; Chen, Qixuan; Hong, Biling

    2009-01-01

    Background The University of Michigan Dioxin Exposure Study (UMDES) was undertaken in response to concerns that the discharge of dioxin-like compounds from the Dow Chemical Company facilities in Midland, Michigan, resulted in contamination of soils in the Tittabawassee River floodplain and areas of the city of Midland, leading to an increase in residents’ body burdens of polychlorinated dibenzodioxins and polychlorinated dibenzofurans. Objectives The UMDES is a hypothesis-driven study designed to answer important questions about human exposure to dioxins in the environment of Midland, where the Dow Chemical Company has operated for > 100 years, and in neighboring Saginaw, Michigan. In addition, the UMDES includes a referent population from an area of Michigan in which there are no unusual sources of dioxin exposure and from which inferences regarding the general Michigan population can be derived. A central goal of the study is to determine which factors explain variation in serum dioxin levels and to quantify how much variation each factor explains. Conclusions In this article we describe the study design and methods for a large population-based study of dioxin contamination and its relationship to blood dioxin levels. The study collected questionnaire, blood, dust, and soil samples on 731 people. This study provides a foundation for understanding the exposure pathways by which dioxins in soils, sediments, fish and game, and homegrown produce lead to increased body burdens of these compounds. PMID:19479025

  2. Scientific and Ethical Approaches for Observational Exposure Studies

    EPA Science Inventory

    Researchers conduct observational human exposure studies to understand how and the extent to which people come into contact with chemicals and environmental stressors in their everyday lives, through the air they breathe, the food and liquids they consume, and the things they tou...

  3. DIETARY EXPOSURES OF YOUNG CHILDREN, PART II: FIELD STUDY

    EPA Science Inventory

    A small, pilot field study was conducted to determine the adequacy of protocols for dietary exposure measurements. Samples were collected to estimate the amount of pesticides transferred from contaminated surfaces or hands to foods of young children and to validate a dietary mod...

  4. (PORTUGAL)THE DETROIT EXPOSURE AND AEROSOL RESEARCH STUDY

    EPA Science Inventory

    The Detroit Exposure and Aerosol Research Study (DEARS) represents an intensive examination of personal, residential and community-based particulate matter and related co-pollutant measurements in Detroit, Michigan. Data from the DEARS will be used as inputs into air quality, la...

  5. School Climate and Exposure to Bullying: A Multilevel Study

    ERIC Educational Resources Information Center

    Låftman, Sara Brolin; Östberg, Viveca; Modin, Bitte

    2017-01-01

    This study investigates associations between aspects of school climate, measured by students' assessments aggregated to the class level, and exposure to bullying, measured at the individual level. The data were derived from the Stockholm School Survey of 2006-2010 with information from 16,418 ninth-grade students (aged 15-16 years) distributed…

  6. School Climate and Exposure to Bullying: A Multilevel Study

    ERIC Educational Resources Information Center

    Låftman, Sara Brolin; Östberg, Viveca; Modin, Bitte

    2017-01-01

    This study investigates associations between aspects of school climate, measured by students' assessments aggregated to the class level, and exposure to bullying, measured at the individual level. The data were derived from the Stockholm School Survey of 2006-2010 with information from 16,418 ninth-grade students (aged 15-16 years) distributed…

  7. DIETARY EXPOSURES OF YOUNG CHILDREN, PART II: FIELD STUDY

    EPA Science Inventory

    A small, pilot field study was conducted to determine the adequacy of protocols for dietary exposure measurements. Samples were collected to estimate the amount of pesticides transferred from contaminated surfaces or hands to foods of young children and to validate a dietary mod...

  8. Scientific and Ethical Approaches for Observational Exposure Studies

    EPA Science Inventory

    Researchers conduct observational human exposure studies to understand how and the extent to which people come into contact with chemicals and environmental stressors in their everyday lives, through the air they breathe, the food and liquids they consume, and the things they tou...

  9. ORD BEST PRACTICES FOR OBSERVATIONAL HUMAN EXPOSURE MEASUREMENT STUDIES

    EPA Science Inventory

    This abstract describes a presentation for the 2007 Society of Toxicology Annual Meeting in Charlotte, NC on March 27, 2007. It will be included in a special Issues Session titled "Scientific and Ethical Considerations in Human Exposure Studies." The presentation desc...

  10. Sunlight Exposure and Breast Density: A Population-Based Study

    PubMed Central

    Wu, Sheng-Hui; So, Edwin; Lam, Tsz-ping; Woo, Jean; Yuen, PY; Qin, Ling; Ku, Susanna

    2013-01-01

    Purpose This study aims to assess the association of sunlight exposure with breast cancer risk, measured by the breast density assessed from Tabár's mammographic pattern in Chinese women. Methods A total of 676 premenopausal women were recruited to participate in this study, in which 650 completed a validated sunlight exposure questionnaire via telephone. The mammograms were classified according to Tabár's classification for parenchyma, and patterns IV & V and I, II & III indicated respectively high and low risk mammographic patterns for breast cancer. The odds ratios (OR) and 95% confidence intervals (CIs) for sun exposure-related variables were estimated using unconditional logistic regression with adjustment for potential confounders. Results Among 646 participants, women with high breast cancer risk (Tabár's patterns IV &V) had less hours spent in the sun than those with low risk (I, II & III) at any age stage. A higher level of sunlight exposure was associated with a significantly lower risk having high risk Tabár's pattern. Women aged 40 to 44 years who were in the highest tertile of lifetime total hours spent in the sun had a multi-adjusted OR of 0.41 (95% CI, 0.18-0.92; p for trend=0.03) compared with those in the lowest tertile (>2.19 hr/day vs. <1.32 hr/day). For hours spent in the sun across the ages of 6 to 12 years, the comparable OR was 0.37 (95% CI, 0.15-0.91; p for trend=0.03). Conclusion These findings suggest that higher sunlight exposure is related to a lower risk of having high risk breast density pattern in premenopausal women. Our results also suggest the most relevant period of exposure is during earlier life. PMID:23843849

  11. Effect on truck drivers' alertness of a 30-min. exposure to bright light: a field study.

    PubMed

    Landström, Ulf; Akerstedt, Torbörn; Byström, Marianne; Nordström, Bertil; Wibom, Roger

    2004-06-01

    Reduced alertness is common during night driving. Light treatment may constitute one countermeasure to reduce sleepiness. To test this idea six professional drivers participated in this study in which they self-administered a 30-min. light treatment during a break in the middle of a night drive of about 9 hours. Two experimental conditions were used, including light exposures with a light box and a light visor. There was a control condition. Alertness was measured on a 100-mm visual analogue scale. No significant effect of light was found, but ratings of sleepiness increased significantly through the night drive. The experimental light treatment was not correlated with any increased wakefulness compared to the drivings where no extra light exposures were carried out.

  12. Fungal exposure in homes of patients with sarcoidosis - an environmental exposure study

    PubMed Central

    2011-01-01

    Background There is increasing evidence that exposure to moulds (fungi) may influence the development of sarcoidosis. To assess the influence of the environmental exposure, a study was undertaken to determine the exposure to fungi in homes of subjects with sarcoidosis. Methods Subjects were patients with clinically established sarcoidosis recruited during the period September 2007 till June 2010. Of these 55 were newly diagnosed and currently under treatment for less than one year, 25 had been treated and had no recurrence and 27 had been treated but had recurrence of the disease. Controls were healthy subjects without any respiratory symptoms (n = 30). Samples of air (about 2.5 m3) were taken in the bedroom of the subjects using a portable pump and cellulose ester filters. The filters were analysed for the content of the enzyme N-acetylhexosaminidase (NAHA) as a marker of fungal cell biomass, using a specific substrate and a fluorescent technique and expressed as NAHA units (U)/m3. Results Compared to controls, subjects undergoing treatment of the disease (newly diagnosed or with recurrence) had significantly higher activities of NAHA in their homes than controls (33.6 and 39.9 vs 10.0 U/m3, p < 0.001 and <0.001). Among controls only 5 out of 30 subjects had levels of NAHA above the second quartile value (14 U/m3). In homes of subjects with newly diagnosed disease with treatment less than one year, values above 14 NAHA U/m3 were found among 35 out of 55 and among those with recurrent disease among 18 out of 27. Conclusions The higher activities of NAHA enzyme found in homes of subjects with active and recurrent sarcoidosis suggest that exposure to fungi is related to the risk of sarcoidosis. Further environmental studies to assess the importance of this exposure for subjects with sarcoidosis are warranted. The results suggest that remedial actions in homes with high levels of fungi may be justified. PMID:21251285

  13. Model refinement for offshore platforms: Experimental study

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Chen, Zongli; Wu, Yanjian

    2017-08-01

    Offshore jacket platforms are widely used in offshore oil and gas exploitation. Finite element models of such structures need to have many degrees of freedom (DOFs) to represent the geometrical detail of complex structures, thereby leading to incompatibility in the number of DOFs of experimental models. To bring them both to the same order while ensuring that the essential eigen- properties of the refined model match those of experimental models, an extended model refinement procedure is presented in this paper. Vibration testing of an offshore jacket platform model is performed to validate the applicability of the proposed approach. A full-order finite element model of the platform is established and then tuned to meet the measured modal properties identified from the acceleration signals. Both model reduction and modal expansion methods are investigated, as well as various scenarios of sensor arrangements. Upon completion of the refinement, the updated jacket platform model matches the natural frequencies of the measured model well.

  14. Experimental Study of Sterilizing Molds by Ultrasound

    NASA Astrophysics Data System (ADS)

    Ren, Jin-lian; Niu, Yong

    1998-02-01

    An ultrasound method of sterilizing aspergillus flavus and fusarium is proposed and demonstrated. The dependence of sterilizing effect on ultrasonic intensity, frequency, and treatment time is experimentally investigated. The density of surviving spores decreases first with increasing ultrasonic frequency and then increases with the further increase of the frequency, that is to say, there exists the optimum frequency 26 kHz at which the killing rate is near 100%. The killing rate seems proportional to the intensity and the time.

  15. Experimental and analytical study of rotating cavitation

    SciTech Connect

    Kamijo, Kenjiro; Shimura, Takashi; Tsujimoto, Yoshinobu

    1994-12-31

    This paper describes experimental and analytical results of rotating cavitation. There are four major sections in this paper. The first section presents the main characteristics of rotating cavitation which was found in the inducer test using a water tunnel. The second section describes the rotating cavitation which occurred in the development test of an LE-7 liquid oxygen pump for the H-II rocket. Also described in this section is how the rotating cavitation was suppressed. The rotating cavitation was the cause of both super synchronous shaft vibration and an unstable head coefficient curve. The third section presents how the theory of rotating cavitation was developed. The final section shows the measured cavitation compliance and mass flow gain factor of the LE-7 pump inducer for comparison of the experimental and analytical results of the rotating cavitation of the LE-7 pump inducer. Almost all the information presented in this paper has already been reported by Kamijo et al. (1977, 1980, 1993, 1993) and by Shimura (1993). In the present paper, the authors attempt to combine and give a clear overview of the experimental and analytical results described in the previous papers to systematically show their experience and findings on rotating cavitation.

  16. Experimental setup to determine the pulse energies and radiant exposures for excimer lasers with repetition rates ranging from 100 to 1050 Hz.

    PubMed

    Mrochen, Michael; Wuellner, Christian; Rose, Kristin; Donitzky, Christof

    2009-10-01

    To evaluate the feasibility of surface profiling for central ablation depth measurements and determine experimentally the required single-pulse energies and radiant exposures to achieve equivalent central ablation depths on bovine corneas for a myopic correction of -6.00 diopters (optical zone 6.5 mm) performed with laser repetition rates ranging from 100 to 1050 Hz. Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland, and WaveLight AG, Erlangen, Germany. Freshly enucleated bovine corneas and poly(methyl methacrylate) (PMMA) plates were photoablated. The shot pattern for the myopic correction was maintained during all experiments; the pulse laser energy was adjusted to achieve equal ablation depths for all repetition rates. Pulse energy, radiant exposure, and pulse duration were monitored to determine the required laser parameter. The variations (standard deviation) of the profile measurements were +/-0.45 microm or less for PMMA and +/-1.50 microm or less for bovine corneas. Measurements with bovine corneas should be performed within 3 minutes or less to avoid larger variations in profile measurements. Increasing the repetition rate from 100 Hz to 1050 Hz required an increase in peak radiant exposure from 400 mJ/cm(2) to 530 mJ/cm(2) to achieve equal ablation for the myopic correction. The required increase in the mean radiant exposure ranged from 190 to 260 mJ/cm(2). Higher-repetition-rate excimer lasers require increased radiant exposure. Further experimental studies should be performed to determine the relevance of spatial and temporal spot positioning, ablation-plume dynamics, and temperature increases during high-repetition-rate laser treatments.

  17. Experimental Bleaching of a Reef-Building Coral Using a Simplified Recirculating Laboratory Exposure System

    EPA Science Inventory

    Determining stressor-response relationships in reef building corals is a critical need for researchers because of global declines in coral reef ecosystems. A simplified recirculating coral exposure system for laboratory testing of a diversity of species and morphologies of reef b...

  18. Experimental Bleaching of a Reef-Building Coral Using a Simplified Recirculating Laboratory Exposure System

    EPA Science Inventory

    Determining stressor-response relationships in reef building corals is a critical need for researchers because of global declines in coral reef ecosystems. A simplified recirculating coral exposure system for laboratory testing of a diversity of species and morphologies of reef b...

  19. Nanosized aerosols from consumer sprays: experimental analysis and exposure modeling for four commercial products

    NASA Astrophysics Data System (ADS)

    Lorenz, Christiane; Hagendorfer, Harald; von Goetz, Natalie; Kaegi, Ralf; Gehrig, Robert; Ulrich, Andrea; Scheringer, Martin; Hungerbühler, Konrad

    2011-08-01

    Consumer spray products are already on the market in the cosmetics and household sector, which suggest by their label that they contain engineered nanoparticles (ENP). Sprays are considered critical for human health, because the lungs represent a major route for the uptake of ENP into the human body. To contribute to the exposure assessment of ENP in consumer spray products, we analyzed ENP in four commercially available sprays: one antiperspirant, two shoe impregnation sprays, and one plant-strengthening agent. The spray dispersions were analyzed by inductively coupled plasma mass spectrometry (ICPMS) and (scanning-) transmission electron microscopy ((S)TEM). Aerosols were generated by using the original vessels, and analyzed by scanning mobility particle sizer (SMPS) and (S)TEM. On the basis of SMPS results, the nanosized aerosol depositing in the respiratory tract was modeled for female and male consumers. The derived exposure levels reflect a single spray application. We identified ENP in the dispersions of two products (shoe impregnation and plant spray). Nanosized aerosols were observed in three products that contained propellant gas. The aerosol number concentration increased linearly with the sprayed amount, with the highest concentration resulting from the antiperspirant. Modeled aerosol exposure levels were in the range of 1010 nanosized aerosol components per person and application event for the antiperspirant and the impregnation sprays, with the largest fraction of nanosized aerosol depositing in the alveolar region. Negligible exposure from the application of the plant spray (pump spray) was observed.

  20. A Quasi-Experimental Analysis of Maternal Altitude Exposure and Infant Birth Weight

    PubMed Central

    Breunig, Ian M.; Link, Bruce G.; Snodgrass, Jeffrey G.; Weiler, Stephan

    2014-01-01

    Objectives. We analyzed singleton births to determine the relationship between birth weight and altitude exposure. Methods. We analyzed 715 213 singleton births across 74 counties from the western states of Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, and Washington from January 1, 2000, to December 31, 2000. Birth data were obtained from the Division of Vital Statistics, National Center for Health Statistics, for registered births. Results. Regression analyses supported previous research by showing that a 1000-meter increase in maternal altitude exposure in pregnancy was associated with a 75.9-gram reduction in birth weight (95% confidence interval = −84.1, −67.6). Quantile regression models indicated significant and near-uniform depressant effects from altitude exposure across the conditional distribution of birth weight. Bivariate sample-selection models showed that a 1000-meter increase in altitude exposure, over and above baseline residential altitude, decreased birth weight by an additional 58.8 grams (95% confidence interval = −98.4, −19.2). Conclusions. Because of calculable health care–related costs associated with lower birth weight, our reported results might be of interest to clinicians practicing at higher altitudes. PMID:24354824

  1. Evaluation of solar exposure on the experimental intoxication by Brachiaria decumbens in sheep

    USDA-ARS?s Scientific Manuscript database

    Twenty-six five-month-old lambs originated from flocks with no previous contact with Brachiaria spp. pastures were divided into three groups. Two groups (GS and GSB) were fed daily with fresh harvested Brachiaria decumbens ad libitum. GS was kept in an area with solar exposure and GSB was kept in st...

  2. The Experimental Determination of Safe Atmospheric Exposure Concentrations of JP-10 Jet Fuel

    DTIC Science & Technology

    1985-11-01

    Globulin WBC Total Protein Differential Cell Counts Glucose MCV Alkaline Phosphatase MCH SGPT MCHC SGOT Sodium Bilirubin BUN Creatinine Following the 1-year...characterized by loss of spermatogonia . In that evidence of long-term testicular damage was lacking, the possibility that this lesion was exposure related

  3. Lessons learned from the Children's Environmental Exposure Research Study.

    PubMed

    Resnik, David B; Wing, Steven

    2007-03-01

    We examined 5 different ethical concerns about the Children's Environmental Exposure Research Study and make some recommendations for future studies of exposure to hazardous environmental agents in the home. Researchers should seek community consultation and participation; make participants aware of all the risks associated with the research, including hazards discovered in the home and uncertainties about the risks of agents under investigation; and take steps to ensure that their studies will not have unfair representation of the poor or people of color. Researchers should also avoid even the appearance of a financial conflict of interest in studies that are likely to be controversial and make it clear to all parties that studies will not intentionally expose subjects to hazardous environmental agents.

  4. Free-Riding Behavior in Vaccination Decisions: An Experimental Study

    PubMed Central

    Ibuka, Yoko; Li, Meng; Vietri, Jeffrey; Chapman, Gretchen B.; Galvani, Alison P.

    2014-01-01

    Individual decision-making regarding vaccination may be affected by the vaccination choices of others. As vaccination produces externalities reducing transmission of a disease, it can provide an incentive for individuals to be free-riders who benefit from the vaccination of others while avoiding the cost of vaccination. This study examined an individual's decision about vaccination in a group setting for a hypothetical disease that is called “influenza” using a computerized experimental game. In the game, interactions with others are allowed. We found that higher observed vaccination rate within the group during the previous round of the game decreased the likelihood of an individual's vaccination acceptance, indicating the existence of free-riding behavior. The free-riding behavior was observed regardless of parameter conditions on the characteristics of the influenza and vaccine. We also found that other predictors of vaccination uptake included an individual's own influenza exposure in previous rounds increasing the likelihood of vaccination acceptance, consistent with existing empirical studies. Influenza prevalence among other group members during the previous round did not have a statistically significant effect on vaccination acceptance in the current round once vaccination rate in the previous round was controlled for. PMID:24475246

  5. MAOA, abuse exposure and antisocial behaviour: 30-year longitudinal study

    PubMed Central

    Fergusson, David M.; Boden, Joseph M.; Horwood, L. John; Miller, Allison L.; Kennedy, Martin A.

    2011-01-01

    Background Recent studies have raised issues concerning the replicability of gene × environment (G × E) interactions involving the monoamine oxidase A (MAOA) gene in moderating the associations between abuse or maltreatment exposure and antisocial behaviour. This study attempted to replicate the findings in this area using a 30-year longitudinal study that has strong resemblance to the original research cohort. Aims To test the hypothesis that the presence of the low-activity MAOA genotype was associated with an increased response to abuse exposure. Method Participants were 398 males from the Christchurch Health and Development Study who had complete data on: MAOA promoter region variable number tandem repeat genotype; antisocial behaviour to age 30; and exposure to childhood sexual and physical abuse. Results Regression models were fitted to five antisocial behaviour outcomes (self-reported property offending; self-reported violent offending; convictions for property/violent offending; conduct problems; hostility) observed from age 16 to 30, using measures of childhood exposure to sexual and physical abuse. The analyses revealed consistent evidence of G × E interactions, with those having the low-activity MAOA variant and who were exposed to abuse in childhood being significantly more likely to report later offending, conduct problems and hostility. These interactions remained statistically significant after control for a range of potentially confounding factors. Findings for convictions data were somewhat weaker. Conclusions The present findings add to the evidence suggesting that there is a stable G × E interaction involving MAOA, abuse exposure and antisocial behaviour across the life course. PMID:21628708

  6. Use of time to pregnancy to study environmental exposures

    SciTech Connect

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

    1986-09-01

    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.

  7. Biomass smoke exposures: toxicology and animal study design.

    PubMed

    Migliaccio, Christopher T; Mauderly, Joe L

    2010-02-01

    The International Biomass Smoke Health Effects (IBSHE) conference was convened in Missoula, MT, to define our current knowledge of smoke exposure and the potential health effects. In an effort to ascertain the relative health effects of an exposure to biomass smoke, numerous studies have utilized either animal or in vitro systems. A wide variety of systems that have been employed ranged from more mainstream animal models (i.e., rodents) and transformed cell lines to less common animal (piglets and dogs) and explant models. The Toxicology and Animal Study Design Workgroup at IBSHE was tasked with an analysis of the use of animal models in the assessment of the health effects of biomass smoke exposure. The present article contains a mini-review of models utilized historically, in addition to the adverse health effects assessed, and an overview of the discussion within the breakout session. The most common question that arose in discussions at the IBSHE conference was from local and federal health departments: What level of smoke is unhealthy? The present workgroup determined categories of exposure, common health concerns, and the availability of animal models to answer key health questions.

  8. Experimental induction of psychogenic illness in the context of a medical event and media exposure.

    PubMed

    Broderick, Joan E; Kaplan-Liss, Evonne; Bass, Elizabeth

    2011-01-01

    Mass psychogenic illness can be a significant problem for triage and hospital surge in disasters; however, research has been largely limited to posthoc observational reports. Reports on the impact of public media during a disaster have suggested both salutary as well as iatrogenic psychological effects. This study was designed to determine if psychogenic illness can be evoked and if media will exacerbate it in a plausible, controlled experiment among healthy community adults. A randomized controlled experiment used a simulated biological threat and elements of social contagion--essential precipitants of mass psychogenic illness. Participants were randomly assigned to one of three groups: no-intervention control group, psychogenic illness induction group, or psychogenic illness induction plus media group. Measures included three assessments of symptom intensity, heart rate, blood pressure, as well as questionnaires to measure potential psychogenic illness risk factors. The two psychogenic induction groups experienced 11 times more symptoms than the control group. Psychogenic illness was observed in both men and women at rates that were not significantly different. Higher rates of lifetime history of traumatic events and depression were associated with greater induction of illness. Media was not found to exacerbate symptom onset. Psychogenic illness relevant to public health disasters can be evoked in an experimental setting. This sets the stage for further research on psychogenic illness and strategies for mitigation.

  9. Experimental induction of psychogenic illness in the context of a medical event and media exposure

    PubMed Central

    Broderick, Joan E.; Kaplan-Liss, Evonne; Bass, Elizabeth

    2011-01-01

    Objectives Mass psychogenic illness can be a significant problem for triage and hospital surge in disasters; however, research has been largely limited to posthoc observational reports. Reports on the impact of public media during a disaster have suggested both salutary as well as iatrogenic psychological effects. This study was designed to determine if psychogenic illness can be evoked and if media will exacerbate it in a plausible, controlled experiment among healthy community adults. Methods A randomized controlled experiment used a simulated biological threat and elements of social contagion—essential precipitants of mass psychogenic illness. Participants were randomly assigned to one of three groups: no-intervention control group, psychogenic illness induction group, or psychogenic illness induction plus media group. Measures included three assessments of symptom intensity, heart rate, blood pressure, as well as questionnaires to measure potential psychogenic illness risk factors. Results The two psychogenic induction groups experienced 11 times more symptoms than the control group. Psychogenic illness was observed in both men and women at rates that were not significantly different. Higher rates of lifetime history of traumatic events and depression were associated with greater induction of illness. Media was not found to exacerbate symptom onset. Conclusions Psychogenic illness relevant to public health disasters can be evoked in an experimental setting. This sets the stage for further research on psychogenic illness and strategies for mitigation. PMID:21870665

  10. Antero-posterior activity changes in the superficial masseter muscle after exposure to experimental pain.

    PubMed

    Türp, Jens C; Schindler, Hans J; Pritsch, Maria; Rong, Qiguo

    2002-04-01

    The aim of this randomized, controlled, double-blind study was to examine how the activation pattern of the masseter muscle changes during natural function when experimental pain is induced in a discrete anterior area of the muscle. In 20 subjects, three bipolar surface electrodes and three intramuscular fine-wire electrodes (antero-posterior mapping) were simultaneously attached above and in the right masseter muscle to record the electromyographic (EMG) activity during unilateral chewing before and after infusion of a 0.9% isotonic and 5% hypertonic saline bolus in the anterior area of the muscle. The activity of the contralateral masseter muscle was registered by surface electrodes. In addition, the development of pain intensity was quantitatively measured with a numerical rating scale (NRS). While both saline concentrations caused pain, the hypertonic solution evoked stronger pain. The experiments also provided evidence of a significant although differential activity reduction of the ipsilateral masseter muscle in the antero-posterior direction. The activity reduction decreased with increasing distance from the location of the infusion. The results support the idea that the strategy of differential activation protects the injured muscle while simultaneously maintaining optimal function.

  11. DEMONSTRATION OF LOW COST, LOW BURDEN EXPOSURE MONITORING STRATEGIES FOR USE IN LONGITUDINAL COHORT STUDIES

    EPA Science Inventory

    A large longitudinal cohort study designed to evaluate the association between children's exposures to environmental agents and health outcomes presents many challenges for exposure monitoring. Exposure of the child must be measured for multiple chemicals through multiple path...

  12. DEMONSTRATION OF LOW COST, LOW BURDEN EXPOSURE MONITORING STRATEGIES FOR USE IN LONGITUDINAL COHORT STUDIES

    EPA Science Inventory

    A large longitudinal cohort study designed to evaluate the association between children's exposures to environmental agents and health outcomes presents many challenges for exposure monitoring. Exposure of the child must be measured for multiple chemicals through multiple path...

  13. Vulnerability of Welders to Manganese Exposure – A Neuroimaging Study

    PubMed Central

    Zaiyang, Long; Yue-Ming, Jiang; Xiang-Rong, Li; William, Fadel; Jun, Xu; Chien-Lin, Yeh; Li-Ling, Long; Hai-Lan, Luo; Jaroslaw, Harezlak; James B, Murdoch; Wei, Zheng; Ulrike, Dydak

    2014-01-01

    Increased manganese (Mn) exposure is known to cause cognitive, psychiatric and motor deficits. Mn exposure occurs in different occupational settings, where the airborne Mn level and the size of respirable particulates may vary considerably. Recently the importance of the role of the cerebral cortex in Mn toxicity has been highlighted, especially in Mn-induced neuropsychological effects. In this study we used magnetic resonance imaging (MRI) to evaluate brain Mn accumulation using T1 signal intensity indices and to examine changes in brain iron content using T2* contrast, as well as magnetic resonance spectroscopy (MRS) to measure exposure-induced metabolite changes non-invasively in cortical and deep brain regions in Mn-exposed welders, Mn-exposed smelter workers and control factory workers with no measurable exposure to Mn. MRS data as well as T1 signal intensity indices and T2* values were acquired from the frontal cortex, posterior cingulate cortex, hippocampus, and thalamus. Smelters were exposed to higher air Mn levels and had a longer duration of exposure, which was reflected in higher Mn levels in erythrocytes and urine than in welders. Nonetheless, welders had more significant metabolic differences compared to controls than did the smelter workers, especially in the frontal cortex. T1 hyperintensities in the globus pallidus were observed in both Mn-exposed groups, but only welders showed significantly higher thalamic and hippocampal T1 hyperintensities, as well as significantly reduced T2* values in the frontal cortex. Our results indicate that (1) the cerebral cortex, in particular the frontal cortex, is clearly involved in Mn neurotoxic effects and (2) in spite of the lower air Mn levels and shorter duration of exposure, welders exhibit more extensive neuroimaging changes compared to controls than smelters, including measurable deposition of Mn in more brain areas. These results indicate that the type of exposure (particulate sizes, dust versus fume) and

  14. Leptospira Exposure and Gardeners: A Case-Control Seroprevalence Study

    PubMed Central

    Alvarado-Esquivel, Cosme; Hernandez-Tinoco, Jesus; Sanchez-Anguiano, Luis Francisco; Ramos-Nevarez, Agar; Cerrillo-Soto, Sandra Margarita; Guido-Arreola, Carlos Alberto

    2016-01-01

    Background Leptospira can be found in soil. However, it is unclear whether occupational exposure to soil may represent a risk for Leptospira infection in humans. Therefore, we sought to determine the association of Leptospira IgG seroprevalence with the occupation of gardener, and to determine the epidemiological characteristics of gardeners associated with Leptospira exposure. Methods We performed a case-control study in 168 gardeners and 168 age- and gender-matched control subjects without gardening occupation in Durango City, Mexico. The seroprevalence of anti-Leptospira IgG antibodies in cases and controls was determined using an enzyme immunoassay. Bivariate and multivariate analyses were used to assess the association of Leptospira exposure and the characteristics of the gardeners. Results Anti-Leptospira IgG antibodies were found in 10 (6%) of 168 gardeners and in 15 (8.9%) of 168 control subjects (odds ratio (OR): 0.64; 95% confidence interval (CI): 0.28 - 1.48; P = 0.40). Multivariate analysis showed that Leptospira seropositivity was positively associated with female gender (OR: 5.82; 95% CI: 1.11 - 30.46; P = 0.03), and negatively associated with eating while working (OR: 0.21; 95% CI: 0.05 - 0.87; P = 0.03). In addition, multivariate analysis showed that high anti-Leptospira levels were associated with consumption of boar meat (OR: 28.00; 95% CI: 1.20 - 648.80; P = 0.03). Conclusions This is the first case-control study of Leptospira exposure in gardeners. Results do not support an association of Leptospira exposure with the occupation of gardener. However, further studies to confirm the lack of this association are needed. The potential role of consumption of boar meat in Leptospira infection deserves further investigation. PMID:26668679

  15. Experimental exposure to propylene glycol mist in aviation emergency training: acute ocular and respiratory effects

    PubMed Central

    Wieslander, G; Norback, D; Lindgren, T

    2001-01-01

    OBJECTIVES—Propylene glycol (PG) (1-2 propanediol; CAS No 57-55-6) is a low toxicity compound widely used as a food additive, in pharmaceutical preparations, in cosmetics, and in the workplace—for example, water based paints, de-icing fluids, and cooling liquids. Exposure to PG mist may occur from smoke generators in discotheques, theatres, and aviation emergency training. Propylene glycol may cause contact allergy, but there is sparse information on health effects from occupational exposure to PG.
METHODS—Non-asthmatic volunteers (n=27) were exposed in an aircraft simulator to PG mist over 1 minute, during realistic training conditions. Geometric mean concentration of PG was 309 mg/m3 (range 176-851 mg/m3), with the highest concentrations in the afternoon. The medical investigation was performed both before and after the exposure (within 15 minutes). It included an estimate of tear film stability break up time, nasal patency by acoustic rhinometry, dynamic spirometry, and a doctor's administered questionnaire on symptoms.
RESULTS—After exposure to PG mist for 1 minute tear film stability decreased, ocular and throat symptoms increased, forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) was slightly reduced, and self rated severity of dyspnoea was slightly increased. No effect was found for nasal patency, vital capacity (VC), FVC, nasal symptoms, dermal symptoms, smell of solvent, or any systemic symptoms. Those exposed to the higher concentrations in the afternoon had a more pronounced increase of throat symptoms, and a more pronounced decrease of tear film stability. In four subjects who reported development of irritative cough during exposure to PG, FEV1 was decreased by 5%, but FEV1 was unchanged among those who did not develop a cough. Those who developed a cough also had an increased perception of mild dyspnoea.
CONCLUSION—Short exposure to PG mist from artificial smoke generators may cause acute ocular and upper airway

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

    EPA Science Inventory

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

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

    EPA Science Inventory

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

  18. Feasibility study of the AOSTA experimental campaign

    NASA Astrophysics Data System (ADS)

    Carta, M.; Blaise, P.; Bethaz, C.; Boccia, F.; Fabrizio, V.; Geslot, B.; Grossi, A.; Gruel, A.

    2016-03-01

    The reduction of the nuclear waste is one of the most important nuclear issues. The high radiotoxicity of the spent fuel is due to plutonium and some minor actinides (MAs) such as neptunium, americium and curium, above all. One way to reduce their hazard is to destroy by fission MAs in appropriate nuclear reactors. To allow the MAs destruction an important effort have been done on the nuclear data due to the poor knowledge in this field. In the framework of one of the NEA Expert Group on Integral Experiments for Minor Actinide Management an analysis of the feasibility of MAs irradiation campaign in the TAPIRO fast research reactor is carried out. This paper provides preliminary results obtained by calculations modelling the irradiation, in different TAPIRO irradiation channels, of some CEA samples coming from the French experimental campaign OSMOSE, loaded with different contents of MAs, in order to access, through particular peak spectrometry, to their capture cross section. On the basis of neutron transport calculation results, obtained by both deterministic and Monte Carlo methods, an estimate of the irradiated samples counting levels from the AOSTA (Activation of OSMOSE Samples in TAPIRO) experimental campaign is provided.

  19. Theoretical and experimental studies of reentry plasmas

    NASA Technical Reports Server (NTRS)

    Dunn, M. G.; Kang, S.

    1973-01-01

    A viscous shock-layer analysis was developed and used to calculate nonequilibrium-flow species distributions in the plasma layer of the RAM vehicle. The theoretical electron-density results obtained are in good agreement with those measured in flight. A circular-aperture flush-mounted antenna was used to obtain a comparison between theoretical and experimental antenna admittance in the presence of ionized boundary layers of low collision frequency. The electron-temperature and electron-density distributions in the boundary layer were independently measured. The antenna admittance was measured using a four-probe microwave reflectometer and these measured values were found to be in good agreement with those predicted. Measurements were also performed with another type of circular-aperture antenna and good agreement was obtained between the calculations and the experimental results. A theoretical analysis has been completed which permits calculation of the nonequilibrium, viscous shock-layer flow field for a sphere-cone body. Results are presented for two different bodies at several different altitudes illustrating the influences of bluntness and chemical nonequilibrium on several gas dynamic parameters of interest. Plane-wave transmission coefficients were calculated for an approximate space-shuttle body using a typical trajectory.

  20. Wright's shifting balance theory: an experimental study.

    PubMed

    Wade, M J; Goodnight, C J

    1991-08-30

    Experimental confirmation of Wright's shifting balance theory of evolution, one of the most comprehensive theories of adaptive evolution, is presented. The theory is regarded by many as a cornerstone of modern evolutionary thought, but there has been little direct empirical evidence supporting it. Some of its underlying assumptions are viewed as contradictory, and the existence and efficacy of the theory's fundamental adaptive process, interdemic selection, is the focus of controversy. Interdemic selection was imposed on large arrays of laboratory populations of the flour beetle Tribolium castaneum in the manner described by Wright: the differential dispersion of individuals from demes of high fitness into demes of low fitness. A significant increase in average fitness was observed in the experimental arrays when compared to control populations with equivalent but random migration rates. The response was not proportional to the selection differential: The largest response occurred with interdemic selection every two generations rather than every generation or every three generations. The results indicate that the interdemic phase of Wright's shifting balance theory can increase average fitness and suggest that gene interactions are involved in the observed response.

  1. Patterns of secretion of transforming growth factor-alpha (TGF-alpha) in experimental silicosis. Acute and subacute effects of cristobalite exposure in the rat.

    PubMed

    Absher, M; Sjöstrand, M; Baldor, L C; Hemenway, D R; Kelley, J

    1993-01-01

    Transforming growth factor-alpha (TGF-alpha) a cytokine having potent mitogenic activity for epithelial and mesenchymal cells, may play a role in the lung remodeling of silicosis. Lung macrophages are among the major cells producing TGF-alpha in a lung tissue. A pivotal event in the cascade of pathologic events leading to pulmonary silicosis is the interaction between inhaled silica and macrophages. TGF-alpha may be critical in directing the proliferation of type II pneumocytes that characterize silicosis. An inhalation model of brief exposure of pathogen-restricted male rats to 25 mg/M3 cristobalite, a highly reactive form of silicon dioxide was used to study experimental silicosis. This model is characterized by a rapid, intense, and sustained increase in macrophages, neutrophils, and lymphocytes in both alveolar and interstitial compartments of the lung. TGF-alpha was measured in an A431 cell proliferation assay made specific with the use of anti-TGF-alpha neutralizing antiserum in epithelial lining fluid (ELF) and conditioned media harvested from cultured alveolar and interstitial macrophages. Soluble TGF-alpha levels found in ELF were slightly elevated above control values during the exposure period, then increased 5-fold during the 20 weeks after the 8-day exposure period. Secretion of TGF-alpha by macrophages was elevated during exposure to cristobalite but then fell during the early post exposure period. Marked elevations in TGF-alpha secretion from both interstitial and alveolar macrophages (10- and 12-fold, respectively) occurred 8-16 weeks after cessation of exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Immortal time bias in drug safety cohort studies: spontaneous abortion following nonsteroidal antiinflammatory drug exposure.

    PubMed

    Daniel, Sharon; Koren, Gideon; Lunenfeld, Eitan; Levy, Amalia

    2015-03-01

    Experimental research of drug safety in pregnancy is generally not feasible because of ethical issues. Therefore, most of the information about drug safety in general and teratogenicity in particular is obtained through observational studies, which require careful methodologic design to obtain unbiased results. Immortal time bias occurs when some cases do not "survive" sufficient time in the study, and as such, they have reduced chances of being defined as "exposed" simply because the durations of their follow-ups were shorter. For example, studies that examine the risk for spontaneous abortions in women exposed to a drug during pregnancy are susceptible to immortal time bias because the chance of drug exposure increases the longer a pregnancy lasts. Therefore, the drug tested may falsely be found protective against the outcome tested. The objective of the current study was to illustrate the extent of immortal time bias using a cohort study of pregnancies assessing the risk for spontaneous abortions following nonsteroidal antiinflammatory drug exposure. We assembled 3 databases containing data on spontaneous abortions, births and drug dispensions to create the present study's cohort. The risk for spontaneous abortion was assessed using 2 statistical analysis methods that were compared for 2 definitions of exposure (dichotomous, exposed vs unexposed, regular Cox regression vs Cox regression with time-varying exposure). Significant differences were found in the risk for spontaneous abortions between the 2 statistical methods, both for groups and for most specific nonsteroidal antiinflammatory drugs (nonselective Cox inhibitors - hazard ratio, 0.70; 95% confidence interval, 0.61-0.94 vs hazard ratio, 1.10; 95% confidence interval, 0.99-1.22 for dichotomous vs time-varying exposure analyses, respectively). Furthermore, a significant correlation was found between the median misclassified immortal time for each drug and the extent of the bias. Immortal time bias can

  3. Environmental exposure and mitochondrial epigenetics: study design and analytical challenges

    PubMed Central

    Byun, Hyang-Min; Baccarelli, Andrea A.

    2015-01-01

    The environment can influence human health and disease in many harmful ways. Many epidemiological studies have been conducted with the aim of elucidating the association between environmental exposure and human disease at the molecular and pathological levels, and such associations can often be through induced epigenetic changes. One such mechanism for this is through environmental factors increasing oxidative stress in the cell, and this stress can subsequently lead to alterations in DNA molecules. The two cellular organelles that contain DNA are the nucleus and mitochondria, and the latter are particularly sensitive to oxidative stress, with mitochondrial functions often disrupted by increased stress. There has been a substantial increase over the past decade in the number of epigenetic studies investigating the impact of environmental exposures upon genomic DNA, but to date there has been insufficient attention paid to the impact upon mitochondrial epigenetics in studying human disease with exposure to environment. Here, in this review, we will discuss mitochondrial epigenetics with regards to epidemiological studies, with particular consideration given to study design and analytical challenges. Furthermore, we suggest future directions and perspectives in the field of mitochondrial epigenetic epidemiological studies. PMID:24402053

  4. Cardiac fibrosis and down regulation of GLUT4 in experimental diabetic cardiomyopathy are ameliorated by chronic exposures to intermittent altitude

    PubMed Central

    Faramoushi, Mahdi; Amir Sasan, Ramin; Sari Sarraf, Vahid; Karimi, Pouran

    2016-01-01

    Introduction: Chronic intermittent hypoxia is considered as a preconditioning status in cardiovascular health to inducing resistance to the low oxygen supply. Diabetic cardiomyopathy leads to inability of the heart to effective circulation of blood preventing of consequent tissue damages so; the aim of this study was elucidation of effect of chronic exposure to hypoxia on Cardiac fibrosis and expression of GLUT4 in experimental diabetic cardiomyopathy. Methods: A total number of 30 rats were randomly divided into three groups; 1: Normoxia control group (NN, n = 10). 2: Normoxia diabetic group (ND, n = 10) that took fat diet for 2 weeks then were injected by streptozotocin (37 mg/kg) and 3: Hypoxia diabetic group (HD, n = 10): that were exposed to chronic intermittent hypoxia (CIH) (altitude ≈3400 m, 14% oxygen for 8 weeks). After hypoxia challenge, plasma metabolic parameters including: fasting blood glucose (FBS), triglyceride (TG) and total cholesterol (TC) were measured by colorimetric assay. Cardiac expression of GLUT4 protein and cardiac collagen accumulation were determined in the excised left ventricle by western blotting, and Masson trichrome staining respectively. Results: Based on resultant data, FBS, TG and TC were significantly (P < 0.05) decreased in HD vs. ND. Homeostasis Model Assessment (HOMA) were also significantly attenuated after exposed to CIH in HD group compared to ND group (P < 0.05). Significant increase in packed cell volume and hemoglobin concentration was observed in HD group compared to ND group (P < 0.05). Comparison of heart wet weight between three groups showed a significant difference (P < 0.05) with lower amount in HD and ND versus NN. Myocardial fibrosis was significantly more pronounced in ND when compared to NN. Eight weeks exposure to hypoxia ameliorated this increase in HD group. Intermittent hypoxia significantly increased GLUT4 protein expression in HD compared to ND group (P < 0.05). Conclusion: Data suggested that CIH

  5. Hypoglycemia and Death in Mice Following Experimental Exposure to an Extract of Trogia venenata Mushrooms

    PubMed Central

    Shen, Tao; Fontaine, Robert E.; Yang, Lin; Zhou, ZhongYu; Gao, Hong; Xu, YanFeng; Qin, Chuan; Yang, ZhuLiang; Liu, JiKai; Huang, WenLi; Zeng, Guang

    2012-01-01

    Background Clusters of sudden unexplained death (SUD) in Yunnan Province, China, have been linked to eating Trogia venenata mushrooms. We evaluated the toxic effect of this mushroom on mice. Methods We prepared extracts of fresh T. venenata and Laccaria vinaceoavellanea mushrooms collected from the environs of a village that had SUD. We randomly allocated mice into treatment groups and administered mushroom extracts at doses ranging from 500 to 3500 mg/kg and water (control) via a gavage needle. We observed mice for mortality for 7 days after a 3500 mg/kg dose and for 24 hours after doses from 500 to 3000 mg/kg. We determined biochemical markers from serum two hours after a 2000 mg/kg dose. Results Ten mice fed T. venenata extract (3500 mg/kg) died by five hours whereas all control mice (L. vinaceoavellanea extract and water) survived the seven-day observation period. All mice died by five hours after exposure to single doses of T. venenata extract ranging from 1500 to 3000 mg/kg, while the four mice exposed to a 500 mg/kg dose all survived. Mice fed 2000 mg/kg of T. venenata extract developed profound hypoglycemia (median  = 0.66 mmol/L) two hours after exposure. Discussion Hypoglycemia and death within hours of exposure, a pattern unique among mushroom toxicity, characterize T. venenata poisoning. PMID:22745677

  6. Transgenerational tobacco smoke exposure and childhood cancer: An observational study

    PubMed Central

    Ortega-García, Juan A; Martin, Marlene; López-Fernández, María T; Fuster-Soler, Jose L; Donat-Colomer, Joaquín; López-Ibor, Blanca; Claudio, Luz; Ferrís-Tortajada, Josep

    2011-01-01

    Aim Although tobacco smoke is an established risk factor for adult cancer, studies of the association between parental smoking and childhood cancer have produced inconsistent results. To investigate the transgenerational relationship between pre-natal and post-natal tobacco smoke exposure from the grandmother’s pregnancies until after the post-natal period and childhood cancer. Methods Exposure to tobacco smoke was recorded for three generations. Data were collected through personal interviews using the paediatric environmental history, and were compared among 128 children with cancer and 128 matched controls. The contingency tables and a logistic multivariable regression model were used to control for possible confounding factors. Results Smoke exposure during oogenesis (maternal grandmother smokers) – odds ratio (OR) 2.2 (95% confidence interval (CI) 1.1–4.9) – and during the mother’ pregnancies – OR 1.8 (95% CI 1.1–3.3) – were significantly associated with an increased risk of childhood cancer. Conclusions Tobacco smoke exposure during the grandmother’s and mother’s pregnancies increase the risk of cancer in the descendants. The results suggest that the biological plausibility of the association between parental smoking and paediatric cancer can be explained by the large latency period of paediatric carcinogenesis. PMID:20412413

  7. A quantitative study of Michigan's criminal HIV exposure law.

    PubMed

    Galletly, Carol L; Pinkerton, Steven D; DiFranceisco, Wayne

    2012-01-01

    The objectives of the project were (1) to determine the extent to which HIV-positive persons living in Michigan were aware of and understood Michigan's criminal HIV exposure law, (2) to examine whether awareness of the law was associated with seropositive status disclosure to prospective sex partners, and, (3) to examine whether awareness of the law was associated with potential negative effects of the law on persons living with HIV (PLWH) including heightened HIV-related stigma, perceived societal hostility toward PLWH, and perceived need to conceal one's HIV infection. The study design was cross-sectional. A statewide sample of 384 PLWH in Michigan completed anonymous pen and paper surveys in 1 of 25 data collection sessions. A majority of participants were aware of Michigan's HIV exposure law. Awareness of the law was not associated with increased seropositive status disclosure to all prospective sex partners, decreased HIV transmission risk behavior, or increased perceived responsibility for HIV transmission prevention. However, awareness of the law was significantly associated with disclosure to a greater proportion of sex partners prior to respondents' first sexual interaction with that partner. Awareness of the law was not associated with increased HIV-related stigma, perceived societal hostility toward PLWH, or decreased comfort with seropositive status disclosure. Evidence of an effect of Michigan's HIV exposure law on seropositive status disclosure was mixed. Further research is needed to examine the various forms of HIV exposure laws among diverse groups of persons living with or at increased risk of acquiring HIV.

  8. A Quantitative Study of Michigan's Criminal HIV Exposure Law

    PubMed Central

    Galletly, Carol L.; Pinkerton, Steven D.; DiFranceisco, Wayne

    2011-01-01

    The objectives of the project were 1) to determine the extent to which HIV-positive persons living in Michigan were aware of and understood Michigan's criminal HIV exposure law, 2) to examine whether awareness of the law was associated with seropositive status disclosure to prospective sex partners, and, 3) to examine whether awareness of the law was associated with potential negative effects of the law on persons living with HIV (PLWH) including heightened HIV-related stigma, perceived societal hostility toward PLWH, and perceived need to conceal one's HIV infection. The study design was cross-sectional. A statewide sample of 384 PLWH in Michigan completed anonymous pen and paper surveys in 1 of 25 data collection sessions. A majority of participants were aware of Michigan's HIV exposure law. Awareness of the law was not associated with increased seropositive status disclosure to all prospective sex partners, decreased HIV transmission risk behavior, or increased perceived responsibility for HIV transmission prevention. However, awareness of the law was significantly associated with disclosure to a greater proportion of sex partners prior to respondents’ first sexual interaction with that partner. Awareness of the law was not associated with increased HIV-related stigma, perceived societal hostility toward PLWH, or decreased comfort with seropositive status disclosure. Evidence of an effect of Michigan's HIV exposure law on seropositive status disclosure was mixed. Further research is needed to examine the various forms of HIV exposure laws among diverse groups of persons living with or at increased risk of acquiring HIV. PMID:21861631

  9. Radiation exposure of fertile women in medical research studies

    SciTech Connect

    Vetter, R.J.

    1988-08-01

    Fertile women may be exposed to ionizing radiation as human subjects in medical research studies. If the woman is pregnant, such exposures may result in risk to an embryo/fetus. Fertile women may be screened for pregnancy before exposure to ionizing radiation by interview, general examination, or pregnancy test. Use of the sensitive serum pregnancy test has become common because it offers concrete evidence that the woman is not pregnant (more specifically, that an embryo is not implanted). Evidence suggests that risk to the embryo from radiation exposure before organogenesis is extremely low or nonexistent. Further, demonstrated effects on organogenesis are rare or inconclusive at fetal doses below 50 mSv (5 rem). Therefore, there may be some level of radiation exposure below which risk to the fetus may be considered essentially zero, and a serum pregnancy test is unnecessary. This paper reviews the fetal risks and suggests that consideration be given to establishing a limit to the fetus of 0.5 mSv (50 mrem), below which pregnancy screening need not include the use of a serum pregnancy test.

  10. Early programing of uterine tissue by bisphenol A: Critical evaluation of evidence from animal exposure studies.

    PubMed

    Suvorov, Alexander; Waxman, David J

    2015-11-01

    Exposure to Bisphenol A (BPA) during the critical window of uterine development has been proposed to program the uterus for increased disease susceptibility based on well-documented effects of the potent xenoestrogen diethylstilbestrol. To investigate this proposal, we reviewed 37 studies of prenatal and/or perinatal BPA exposure in animal models and evaluated evidence for: molecular signatures of early BPA exposure; the development of adverse uterine health effects; and epigenetic changes linked to long-term dysregulation of uterine gene expression and health effects. We found substantial evidence for adult uterine effects of early BPA exposure. In contrast, experimental support for epigenetic actions of early BPA exposure is very limited, and largely consists of effects on Hoxa gene DNA methylation. Critical knowledge gaps were identified, including the need to fully characterize short-term and long-term uterine gene responses, interactions with estrogens and other endogenous hormones, and any long-lasting epigenetic signatures that impact adult disease. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Theoretical and experimental studies of elementary physics

    SciTech Connect

    Bodek, A.; Ferbel, T.; Melissinos, A.C.; Olsen, S.; Slattery, P.; Tipton, P.; Das, A.; Hagen, C.R.; Rajeev, S.G.; Okubo, S.

    1992-04-30

    The experimental high energy physics program is directed toward the execution of experiments that probe the basic constituents of matter and the forces between them. These experiments are carried out at national and international accelerator facilities. At the current time, we are primarily concentrating on the following projects: Direct photon production in hadronic reactions (Fermilab E706); Production of hybrid mesons in the nuclear Coulomb field; The D-Zero experiment at the Tevatron collider; Deep inelastic neutrino- and electron-nucleon scattering at FNAL and SLAC; Nonlinear QED at critical field strengths at SLAC; The Experiments at KEK (AMY, 17keV neutrino); The CDF experiment at the Tevatron collider; and SSC-related detector R D on scintillating tile- and diamond-based calorimetry and microstrip tracking detectors.

  12. Experimental clean combustor program: Noise study

    NASA Technical Reports Server (NTRS)

    Sofrin, T. G.; Riloff, N., Jr.

    1976-01-01

    Under a Noise Addendum to the NASA Experimental Clean Combustor Program (ECCP) internal pressure fluctuations were measured during tests of JT9D combustor designs conducted in a burner test rig. Measurements were correlated with burner operating parameters using an expression relating farfield noise to these parameters. For a given combustor, variation of internal noise with operating parameters was reasonably well predicted by this expression but the levels were higher than farfield predictions and differed significantly among several combustors. For two burners, discharge stream temperature fluctuations were obtained with fast-response thermocouples to allow calculation of indirect combustion noise which would be generated by passage of the temperature inhomogeneities through the high pressure turbine stages of a JT9D turbofan engine. Using a previously developed analysis, the computed indirect combustion noise was significantly lower than total low frequency core noise observed on this and several other engines.

  13. Experimental study of external fuel vaporization

    NASA Technical Reports Server (NTRS)

    Szetela, E. J.; Tevelde, J. A.

    1982-01-01

    The fuel properties used in the design of a flash vaporization system for aircraft gas turbine engines were evaluated in experiments using a flowing system to determine critical temperature and pressure, boiling points, dew points, heat transfer coefficients, deposit formation rates, and deposit removal. Three fuels were included in the experiments: Jet-A, an experimental referree broad specification fuel, and a premium No. 2 diesel fuel. Engine conditions representing a NASA Energy Efficient Engine at sea-level take-off, cruise, and idle were simulated in the vaporization system and it was found that single phase flow was maintained in the heat exchanger and downstream of the throttle. Deposits encountered in the heat exchanger represented a thermal resistance as high as 1300 sq M K/watt and a deposit formation rate over 1000 gC/sq cm hr.

  14. Experimental and theoretical study of ornidazole

    NASA Astrophysics Data System (ADS)

    Rajesh, P.; Gunasekaran, S.; Gnanasambandan, T.; Seshadri, S.

    2016-01-01

    The Fourier transform infrared (FT-IR) and the Fourier transform Raman (FT-Raman) spectra of the title molecule in solid phase were recorded in the region 4000-400 cm- 1 and 4000-100 cm- 1 respectively. The geometrical parameters and energies were investigated with the help of Density Functional Theory (DFT) employing B3LYP method and 6-31G (d, p) basis set. The analysis was supported by electrostatic potential maps and calculation of HOMO-LUMO. UV, FT-IR and FT-Raman spectra of ornidazole were calculated and compared with experimental results. Thermodynamic properties like entropy, heat capacity, have been calculated for the molecule. The predicted first hyperpolarizability also shows that the molecule might have a reasonably good non-linear optical (NLO) behavior. The intramolecular contacts have been interpreted using natural bond orbital (NBO) and natural localized molecular orbital (NLMO) analysis.

  15. Experimental land observing data system feasibility study

    NASA Technical Reports Server (NTRS)

    Buckley, J. L.; Kraiman, H.

    1982-01-01

    An end-to-end data system to support a Shuttle-based Multispectral Linear Array (MLA) mission in the mid-1980's was defined. The experimental Land Observing System (ELOS) is discussed. A ground system that exploits extensive assets from the LANDSAT-D Program to effectively meet the objectives of the ELOS Mission was defined. The goal of 10 meter pixel precision, the variety of data acquisition capabilities, and the use of Shuttle are key to the mission requirements, Ground mission management functions are met through the use of GSFC's Multi-Satellite Operations Control Center (MSOCC). The MLA Image Generation Facility (MIGF) combines major hardware elements from the Applications Development Data System (ADDS) facility and LANDSAT Assessment System (LAS) with a special purpose MLA interface unit. LANDSAT-D image processing techniques, adapted to MLA characteristics, form the basis for the use of existing software and the definition of new software required.

  16. Experimental study of external fuel vaporization

    NASA Technical Reports Server (NTRS)

    Szetela, E. J.; Tevelde, J. A.

    1982-01-01

    The fuel properties used in the design of a flash vaporization system for aircraft gas turbine engines were evaluated in experiments using a flowing system to determine critical temperature and pressure, boiling points, dew points, heat transfer coefficients, deposit formation rates, and deposit removal. Three fuels were included in the experiments: Jet-A, an experimental referree broad specification fuel, and a premium No. 2 diesel fuel. Engine conditions representing a NASA Energy Efficient Engine at sea-level take-off, cruise, and idle were simulated in the vaporization system and it was found that single phase flow was maintained in the heat exchanger and downstream of the throttle. Deposits encountered in the heat exchanger represented a thermal resistance as high as 1300 sq M K/watt and a deposit formation rate over 1000 gC/sq cm hr.

  17. Experimental studies of collision and fragmentation phenomena

    NASA Technical Reports Server (NTRS)

    Hartmann, William K.; Davis, D. R.; Weidenschilling, S. J.

    1987-01-01

    The reduction and publication of an extensive data set collected in experiments over several years at Ames and PSI is briefly examined. Hartmann has been assembling data sets from his experiments on catastrophic fragmentation of various materials, including basalt, other igneous rock, ice, and weak dirt clods. Weidenschilling and Davis have continued to gather and reduce data on oblique impacts. The data indicate a power law distribution of ejecta mass vs. velocity, with a slope that is independent of azimuth, and does not vary with impact angle from normal impacts to at least 75 deg from vertical. In order to improve models of coagulation of dust aggregates in the solar nebula, SJW developed an apparatus for drop tests of fragile projectiles. Davis and Weidenschilling continued to collect and analyze experimental data on collisional catastrophic disruption at the Ames Vertical Gun Range.

  18. [Experimental studies of sonography of the meniscus].

    PubMed

    Casser, H R; Füsting, M; Tenbrock, F

    1991-01-01

    The aim of this examination was to recognize and, if possible, avoid the origin of artifact images in sonograms caused anatomically and by the physics of ultrasound. Experimental investigations were carried out in a waterbath on models of knee joints using Schlierenoptics and on specimens from corpse knees. When a sector transducer was used, the artifact images that originated in the joint cavity appeared outside the cavity on the sonogram so that there were no danger of mistaking them for reflected images of tears in lesions of the meniscus. In sonography, the surfaces of tears reflect a strong signal, but diagnosis depends on the position of the edges of the tears to the direction of the ultrasonic waves, which means to get a reliable record of tears of the meniscus is only possible by means of a dynamic examination technique.

  19. Experimental Study of Torsional Column Failure

    NASA Technical Reports Server (NTRS)

    Nile, Alfred S

    1939-01-01

    Thirty-three 24ST aluminum-alloy 2- by 2- by 0.10-inch channels, with lengths ranging from 10 to 90 inches were tested at Stanford University in compression to obtain an experimental verification of the theoretical formulas for torsional failure developed by Eugene E. Lundquist of the N.A.C.A. The observed critical loads and twist-axis locations were sufficiently close to the values obtained from the formulas to establish the substantial validity of the latter. The differences between observed and computed results were small enough to be accounted for by small and mostly unavoidable differences between actual test conditions and those assumed in deriving the formulas. Some data were obtained from the shorter specimens regarding the growth of the buckles that resulted in local buckling failure.

  20. Experimental studies on sexual reproduction in diatoms.

    PubMed

    Chepurnov, Victor A; Mann, David G; Sabbe, Koen; Vyverman, Wim

    2004-01-01

    The diatoms are the most speciose group of algae, having global ecological significance in the carbon and silicon cycles. They are almost unique among algae in being diplontic, and sexual reproduction is an obligate stage in the life cycle of most diatom species. It is unclear which are the principal factors that have fostered the evolutionary success of diatoms, but the unique life cycle (which is correlated with a curious wall structure and cell division mechanism) and size-dependent control of sexuality must have played an important part. Progress in understanding life cycle dynamics and their interrelationships with population biology and evolution will depend on how successfully sex can be initiated and manipulated experimentally, and our review provides a foundation for such work. Relevant data are scattered in time and come mostly from non-English publications, producing a false impression of diatoms as recalcitrant with respect to sexualization. Recent advances dependent on experimental cultures include the discovery of widespread heterothallism (including some complex types of behavior) in pennate diatoms, sexual diversity among clones of centric diatoms, more flexible size restitution strategies in centric diatoms than had been suspected, and use of reproductive isolation as a criterion in diatom taxonomy. We identify unsolved problems in the life history of diatoms, including aspects of sexualization, cell-cell recognition, sexual reproduction, and the development of the special expanding cell (the auxospore), which is crucial to morphogenesis in this group. Some of these problems are being addressed using modern molecular genetic tools, and progress will be facilitated when whole-genome sequences are published (e.g., for Thalassiosira pseudonana). Problems of culture maintenance and methods for manipulating the life cycle are discussed.

  1. Computational and experimental study of laminar flames

    SciTech Connect

    Smooke, Mitchell

    2015-05-29

    During the past three years, our research has centered on an investigation of the effects of complex chemistry and detailed transport on the structure and extinction of hydrocarbon flames in coflowing axisymmetric configurations. We have pursued both computational and experimental aspects of the research in parallel on both steady-state and time-dependent systems. The computational work has focused on the application of accurate and efficient numerical methods for the solution of the steady-state and time-dependent boundary value problems describing the various reacting systems. Detailed experimental measurements were performed on axisymmetric coflow flames using two-dimensional imaging techniques. Previously, spontaneous Raman scattering, chemiluminescence, and laser-induced fluorescence were used to measure the temperature, major and minor species profiles. Particle image velocimetry (PIV) has been used to investigate velocity distributions and for calibration of time-varying flames. Laser-induced incandescence (LII) with an extinction calibration was used to determine soot volume fractions, while soot surface temperatures were measured with three-color optical pyrometry using a color digital camera. A blackbody calibration of the camera allows for determination of soot volume fraction as well, which can be compared with the LII measurements. More recently, we have concentrated on a detailed characterization of soot using a variety of techniques including time-resolved LII (TiRe-LII) for soot primary particles sizes, multi-angle light scattering (MALS) for soot radius of gyration, and spectrally-resolved line of sight attenuation (spec-LOSA). Combining the information from all of these soot measurements can be used to determine the soot optical properties, which are observed to vary significantly depending on spatial location and fuel dilution. Our goal has been to obtain a more fundamental understanding of the important fluid dynamic and chemical interactions in

  2. SUMMARY OF BIOLOGICAL AND ENVIRONMENTAL MONITORING RESULTS FROM THE AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY

    EPA Science Inventory

    The Agricultural Health Study (AHS) is a prospective epidemiologic study of pesticide applicators and spouses in Iowa and North Carolina. Exposure to 2,4-D or chlorpyrifos was measured for a subset of applicators and their families in the AHS Pesticide Exposure Study to assess...

  3. INTERIM RESULTS FROM THE AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY

    EPA Science Inventory

    The Agricultural Health Study (AHS) is a prospective epidemiological study of pesticide applicators and their spouses in Iowa and North Carolina. Exposure to 2,4-D or chlorpyrifos is being measured for a subset of applicators in the AHS Pesticide Exposure Study to assess expos...

  4. AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY: STATUS UPDATE AND PRELIMINARY RESULTS

    EPA Science Inventory

    The Agricultural Health Study (AHS) is a prospective epidemiological study of pesticide applicators and their spouses in Iowa and North Carolina. Exposure to 2,4-D or chlorpyrifos is being measured for a subset of applicators in the AHS Pesticide Exposure Study to assess expos...

  5. AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY: STATUS UPDATE AND PRELIMINARY RESULTS

    EPA Science Inventory

    The Agricultural Health Study (AHS) is a prospective epidemiological study of pesticide applicators and their spouses in Iowa and North Carolina. Exposure to 2,4-D or chlorpyrifos is being measured for a subset of applicators in the AHS Pesticide Exposure Study to assess expos...

  6. INTERIM RESULTS FROM THE AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY

    EPA Science Inventory

    The Agricultural Health Study (AHS) is a prospective epidemiological study of pesticide applicators and their spouses in Iowa and North Carolina. Exposure to 2,4-D or chlorpyrifos is being measured for a subset of applicators in the AHS Pesticide Exposure Study to assess expos...

  7. SUMMARY OF BIOLOGICAL AND ENVIRONMENTAL MONITORING RESULTS FROM THE AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY

    EPA Science Inventory

    The Agricultural Health Study (AHS) is a prospective epidemiologic study of pesticide applicators and spouses in Iowa and North Carolina. Exposure to 2,4-D or chlorpyrifos was measured for a subset of applicators and their families in the AHS Pesticide Exposure Study to assess...

  8. An experimental study on photothermal damage to tissue: the role of irradiance and wavelength

    NASA Astrophysics Data System (ADS)

    Yildiz, F.; Gulsoy, M.; Cilesiz, I.

    2016-09-01

    Laser exposure time and irradiance are crucial parameters governing the process of thermal damage. The goal of our in vitro study was to study and determine optimal parameters for the onset of coagulation and carbonization at three different wavelengths (980, 1070 and 1940 nm). We also compared photothermal effects at these three wavelengths by varying laser exposure time and irradiance. Fresh bovine liver specimens were used for experimentation. The onset of thermal damage at different irradiances and for different exposure time was studied macroscopically and histologically. Photothermal damage or lesion volume generally decreased with irradiance and increasing exposure time. We observed an exponential and linear relationship between irradiance and exposure time for specific thermal endpoints. These specific endpoints were the onset of (i) coagulation, and (ii) carbonization. The time interval or difference between these specific endpoints termed as Δt (t carbonization  -  t coagulation) (s) was also determined. This relation between irradiance and exposure time will make possible the pre-estimation of thermal tissue lesion volume before operation, and photothermal therapy may thus be performed with minimum side effects on liver tissue.

  9. Cost/variance optimization for human exposure assessment studies.

    PubMed

    Whitmore, Roy W; Pellizzari, Edo D; Zelon, Harvey S; Michael, Larry C; Quackenboss, James J

    2005-11-01

    The National Human Exposure Assessment Survey (NHEXAS) field study in EPA Region V (one of three NHEXAS field studies) provides extensive exposure data on a representative sample of 249 residents of the Great Lakes states. Concentration data were obtained for both metals and volatile organic compounds (VOCs) from multiple environmental media and from human biomarkers. A variance model for the logarithms of concentration measurements is used to define intraclass correlations between observations within primary sampling units (PSUs) (nominally counties) and within secondary sampling units (SSUs) (nominally Census blocks). A model for the total cost of the study is developed in terms of fixed costs and variable costs per PSU, SSU, and participant. Intraclass correlations are estimated for media and analytes with sufficient sample sizes. We demonstrate how the intraclass correlations and variable cost components can be used to determine the sample allocation that minimizes cost while achieving pre-specified precision constraints for future studies that monitor environmental concentrations and human exposures for metals and VOCs.

  10. Isocyanate exposures in autobody shop work: the SPRAY study.

    PubMed

    Sparer, Judy; Stowe, Meredith H; Bello, Dhimiter; Liu, Youcheng; Gore, Rebecca J; Youngs, Fred; Cullen, Mark R; Redlich, Carrie A; Woskie, Susan R

    2004-09-01

    Isocyanates, known to cause respiratory sensitization and asthma, are widely used in automotive refinishing where exposures to aliphatic polyisocyanates occur by both inhalation and skin contact. The work reported here, the characterization of isocyanate exposure in the autobody industry, was part of an epidemiologic study of workers in 37 autobody shops in Connecticut. This article describes workplaces, tasks, and controls, and outlines the frequency, duration, and intensity of isocyanate exposures. Personal air samples taken outside of respirators had median concentrations of 66.5 microg NCO/m3 for primer, 134.4 microg (NCO)/m3 for sealer, and 358.5 microg NCO/m3 for clearcoat. Forty-eight percent of primer, 66% of sealer, and 92% of clearcoat samples exceeded the United Kingdom Health and Safety Executive guideline for isocyanate, though none exceeded the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit for monomer. Nonisocyanate-containing primers and sealers are used in more than half the shops, but nonisocyanate clearcoats are rare. Eighty-two percent of personal samples taken within a spray booth exceeded the U.K. guideline: 81% of those in downdraft spray booths, 74% in semidowndraft booths, and 92% in crossdraft booths. Only 8% of shops reported that spraying is done exclusively in spray booths. All painters wore some type of respirator. In 30% of shops, painters used supplied air respirators; the rest relied on half face organic vapor cartridge respirators with N95 overspray pads. All shops provided some type of gloves, usually latex, not recommended for isocyanate protection. Despite improvements in autobody shop materials, practices, and controls, there are still opportunities for substantial exposures to isocyanates.

  11. Biomass smoke exposures: health outcomes measures and study design.

    PubMed

    Noonan, Curtis W; Balmes, John R

    2010-02-01

    Epidemiological studies of biomass smoke health effects have been conducted in a variety of settings and with a variety of study designs. The Health Effects Workgroup discussed several approaches for the investigation of health effects in communities exposed to wood smoke from nearby wildland fires, intentional agricultural burning, or residential biomass burning devices such as woodstoves or cookstoves. This presentation briefly reviews observational and intervention studies that have been conducted within these exposure settings. The review is followed by a summary of discussion points among the workgroup members with particular emphasis on study design and the use of biomarkers for assessing outcomes in biomass smoke-exposed populations.

  12. Molecular simulations and experimental studies of zeolites

    NASA Astrophysics Data System (ADS)

    Moloy, Eric C.

    Zeolites are microporous aluminosilicate tetrahedral framework materials that have symmetric cages and channels with open-diameters between 0.2 and 2.0 nm. Zeolites are used extensively in the petrochemical industries for both their microporosity and their catalytic properties. The role of water is paramount to the formation, structure, and stability of these materials. Zeolites frequently have extra-framework cations, and as a result, are important ion-exchange materials. Zeolites also play important roles as molecular sieves and catalysts. For all that is known about zeolites, much remains a mystery. How, for example, can the well established metastability of these structures be explained? What is the role of water with respect to the formation, stabilization, and dynamical properties? This dissertation addresses these questions mainly from a modeling perspective, but also with some experimental work as well. The first discussion addresses a special class of zeolites: pure-silica zeolites. Experimental enthalpy of formation data are combined with molecular modeling to address zeolitic metastability. Molecular modeling is used to calculate internal surface areas, and a linear relationship between formation enthalpy and internal surface areas is clearly established, producing an internal surface energy of approximately 93 mJ/m2. Nitrate bearing sodalite and cancrinite have formed under the caustic chemical conditions of some nuclear waste processing centers in the United States. These phases have fouled expensive process equipment, and are the primary constituents of the resilient heels in the bottom of storage tanks. Molecular modeling, including molecular mechanics, molecular dynamics, and density functional theory, is used to simulate these materials with respect to structure and dynamical properties. Some new, very interesting results are extracted from the simulation of anhydrous Na6[Si6Al 6O24] sodalite---most importantly, the identification of two distinct

  13. A novel approach for exposure assessment in air pollution epidemiological studies using neuro-fuzzy inference systems: Comparison of exposure estimates and exposure-health associations.

    PubMed

    Blanes-Vidal, Victoria; Cantuaria, Manuella Lech; Nadimi, Esmaeil S

    2017-04-01

    Many epidemiological studies have used proximity to sources as air pollution exposure assessment method. However, proximity measures are not generally good surrogates because of their complex non-linear relationship with exposures. Neuro-fuzzy inference systems (NFIS) can be used to map complex non-linear systems, but its usefulness in exposure assessment has not been extensively explored. We present a novel approach for exposure assessment using NFIS, where the inputs of the model were easily-obtainable proximity measures, and the output was residential exposure to an air pollutant. We applied it to a case-study on NH3 pollution, and compared health effects and exposures estimated from NFIS, with those obtained from emission-dispersion models, and linear and non-linear regression proximity models, using 10-fold cross validation. The agreement between emission-dispersion and NFIS exposures was high (Root-mean-square error (RMSE) =0.275, correlation coefficient (r)=0.91) and resulted in similar health effect estimates. Linear models showed poor performance (RMSE=0.527, r=0.59), while non-linear regression models resulted in heterocedasticity, non-normality and clustered data. NFIS could be a useful tool for estimating individual air pollution exposures in epidemiological studies on large populations, when emission-dispersion data are not available. The tradeoff between simplicity and accuracy needs to be considered. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. An experimental study of jet exhaust simulation

    NASA Technical Reports Server (NTRS)

    Compton, W. B., III

    1975-01-01

    Afterbody drag predictions for jet aircraft are usually made experimentally with the jet exhaust flow simulated. The physical gas properties of the fluid used for the model jet exhaust can affect the accuracy of simulation of the airplane's jet exhaust plume. The effect of the accuracy of this simulation on afterbody drag was investigated by wind-tunnel tests with single engine model. In addition to unheated air as the exhaust gas, the decomposition products of three different concentrations of hydrogen peroxide were utilized. The air jet simulation consistently resulted in higher boattail drag than hydrogen peroxide simulation. The differences in drag for the various exhaust gases are attributed to different plume shapes and entrainment properties of the gases. The largest differences in drag due to exhaust gas properties were obtained for the combination of high transonic Mach numbers and high boattail angles. For these conditions, the current data indicate that the use of air to simulate a nonafterburning turbojet exhaust can result in an increase in afterbody amounting to 20 percent of the nonafterburning turbojet value.

  15. Experimental study on HVAC sound parameters

    NASA Astrophysics Data System (ADS)

    Bujoreanu, C.; Benchea, M.

    2016-08-01

    HVAC system represent major source of buildings internal noise and therefore they are designed to provide a human acoustic comfort besides the thermal and air quality requirements. The paper experimentally investigates three types of commercial air handler units (AHU) with different ducts cross-section sizes and inlet-outlet configuration. The measurements are performed in an anechoic room. The measurements are carried out at different fan's speeds, ranging the power-charge from 30-100% while the duct air flow is slowly adjusted from full open to full closed, between 0-500 Pa. The sound pressure levels of the radiant units are rated using NR curves. Also, the supply and the outdoor ducts sound levels are compared in order to point the frequencies where the noise must be reduced. Third-octave band analysis of random noise of an air handling unit from a HVAC system is realized, using measurement procedures that agrees the requirements of the ISO 3744:2011 and ISO 5136:2010 standards. The comparatively results highlight the effects of the geometry, air flow pressure and power-charging dependencies upon the sound level. This is the start for a noise reduction strategy.

  16. Experimental studies with Stronglyloides papillosus in goats.

    PubMed

    Pienaar, J G; Basson, P A; du Plessis, J L; Collins, H M; Naude, T W; Boyazoglu, P A; Boomker, J; Reyers, F; Pienaar, W L

    1999-09-01

    Unusual clinical and pathological observations in the field in goats and sheep suffering from Strongyloides papillosus infection prompted experimental work on this parasite. Goats were infected percutaneously with either single or multiple, low or high levels of S. papillosus. Young goats up to 12 months of age were found to be the most susceptible. Some animals, however, showed substantial resistance to infective doses. Clinical signs included transient diarrhoea, misshapen, elongated faecal pellets terminally, dehydration, anorexia, cachexia, gnashing of teeth, foaming at the mouth, anaemia and nervous signs such as ataxia, a wide-based stance, stupor and nystagmus. A 'pushing syndrome' was seen in 22% of the animals. The pathological changes are described and included enteritis, status spongiosus in the brain, hepatosis leading to rupture of the liver, nephrosis, pulmonary oedema, interstitial pneumonia and pneumonia. About 6% of the goats died acutely from fatal hepatic rupture. The development of an acquired immunity was determined. The immunity elicited an allergic skin reaction at the application site of larvae or injection sites of larval metabolites. This immunity, however, could be breached by large doses of larvae. The most profound clinicopathological changes induced by the parasites were an anaemia (most pronounced in the young goats) and hypophosphataemia. Trace element analyses provided evidence of Cu, Mn and possibly Se deficiencies in some goats.

  17. Experimental Studies of Mars-Analog Brines

    NASA Technical Reports Server (NTRS)

    Moore, Jeffrey M.; Bullock, Mark A.

    1999-01-01

    Evaporite deposits may represent significant sinks of mobile cations (e.g., those of Ca, N, Mg, and Fe) and anions (e.g., those of C, N, S, and Cl) among the materials composing the Martian surface and upper crust. Carbon and nitrogen are especially interesting because of their role as atmospheric gases which can become incorporated into crustal rocks. However, the nature of evaporite precursor brines formed under Martian conditions is poorly understood. To date, only a very limited number of laboratory investigations have been reported which have any bearing on a better understanding of various processes related to brine or evaporite formation on Mars. Here we report on preliminary laboratory experiments that exposed igneous minerals analogous to those in Martian (Shergottites, Nakhlites, and Chassigny (SNC) group) meteorites to a simulated Martian atmosphere and pure, deoxygenated water. Analysis of the water over intervals of time approaching 1 year showed that atmospheric gases dissolved to form carbonate and nitrate ions while minerals dissolved to form sulfate and chloride along with various cations. On an annual basis, ion formation gave a carbonate/sulfate ratio that is comparable to the ratio found among salts in SNC meteorites. The sulfate/chloride ratio of the experimental brines is higher than in SNC meteorites but lower than in surface soils measured at the Viking and Pathfinder landing sites.

  18. Experimental studies of a drumlike silencer

    NASA Astrophysics Data System (ADS)

    Choy, Y. S.; Huang, Lixi

    2002-11-01

    The theoretical finding of the broadband performance of a reactive silencer is validated experimentally. The silencer consists of two highly stretched membranes lining part of the duct and backed by two long and shallow cavities. The test rig was built with a small square duct of 5 cm in dimension, and each cavity is 5 cm deep and 25 cm long. Two types of metal foils, stainless steel and copper, were used, and the lowest membrane-to-air mass ratio was 1.3. A transmission loss in excess of 10 dB was achieved over more than one octave band. For one configuration close to the optimal parameters, the predicted ratio of the frequency band limits is 2.47, while the experiment gave 2.35. Three spectral peaks were found in the stopband, as predicted, but the peaks were broader than prediction, indicating the presence of significant sound energy dissipation mechanisms. Comparison with theoretical simulation shows that the cavity damping dominates over membrane friction. Tests using heavier membranes and membrane with different levels of tension also agree with predictions. Issues of practical implementation of the concept as a flow-through silencer are also addressed. copyright 2002 Acoustical Society of America.

  19. CVD parameter study using strategy of experimentation

    SciTech Connect

    Williams, R.E.

    1984-07-01

    An experimental design strategy was used to determine the operating characteristics of an apparatus for forming tungsten-rhenium (W-Re) alloys by chemical vapor deposition. The metal deposits were made at 650/sup 0/C by the hydrogen reduction of a 10 percent rhenium hexafluoride and 90 percent gas mixture at 0.66 to 4.00 kPa (5 to 30 torr). Hydrogen flow rates ranged from 550 to 2770 ..mu..mol/s and mixed metal fluoride flows ranged from 41 to 130 ..mu..mol/s. An operating point was sought that would produce a high strength alloy, so the deposition results were fit by least squares regression to second order response equations. Seven properties were measured: deposition rate, average composition, maximum composition, minimum composition, sample standard deviation of the composition, microhardness as a measure of the amount of A15 phase, and as-deposited surface quality. A set of operating parameters was determined that was predicted to yield a 23 w/o Re alloy with an 1100 DPH (diamond pyramid hardness) microhardness.

  20. Experimental model to study sedimentary kidney stones.

    PubMed

    Grases, F; Llobera, A

    1998-01-01

    An experimental model to reproduce, to some extent, the conditions prevailing during the formation of the so-called sedimentary urinary stones, was developed. The results obtained demonstrated that in the absence of organic matter no calcium phosphate crystals were deposited in cavities with scarce liquid renovation. Nevertheless, in such case a regular hydroxyapatite layer was developed on the walls around the cavity. The presence of crystallization inhibitors cannot stop indefinitely the crystal development. Therefore, phytate manifested important inhibitory effects in concentrations normally found in urine (0.77-1.54 x 10(-6) mol/l), whereas citrate only manifested important inhibitory effects when found at high urinary concentrations (2.64 x 10(-3) mol/l). When mucin (a glycoprotein) was present in the urine, a clear deposit of calcified organic material was formed. The organic matter appeared mixed with the spherulites of hydroxyapatite, this demonstrating the capacity of the glycoprotein agglomerates to act as heterogeneous nucleants of calcium salts and their important role in the formation of sedimentary stones. The structural features of the obtained in vitro deposits were compared with the fine structure of human sedimentary phosphate calculi. Scanning electron microscopy images demonstrated a good correspondence between in vitro experiments and in vivo observations.

  1. Experimental study of low Reynolds number nozzles

    NASA Technical Reports Server (NTRS)

    Grisnik, Stanley P.; Smith, Tamara A.; Saltz, Larry E.

    1987-01-01

    High-performance electrothermal thrusters operate in a low nozzle-throat Reynolds number regime. Under these conditions, the flow boundary layer occupies a large volume inside the nozzle, contributing to large viscous losses. Four nozzles (conical, bell, trumpet, and modified trumpet) and a sharp-edged orifice were evaluated over a Reynolds number range of 500 to 9000 with unheated nitrogen and hydrogen. The nozzles showed significant decreases in specific impulse efficiency with decreasing Reynolds number. At Reynolds numbers less than 1000, all four nozzles were probably filled with a large boundary layer. The discharge coefficient decreased with Reynolds number in the same manner as the specific impulse efficiency. The bell and modified trumpet nozzles had discharge coefficients 4 to 8 percent higher than those of the cone or trumpet nozzles. The Two-Dimensional Kinetics (TDK) nozzle analysis computer program was used to predict nozzle performance. The results were then compared to the experimental results in order to determine the accuracy of the program within this flow regime.

  2. An experimental study of human birth models

    NASA Astrophysics Data System (ADS)

    Baumer, Alexa; Gossmann, Roseanna; Fauci, Lisa J.; Leftwich, Megan C.

    2016-11-01

    The laboring uterus is a complex and dynamic fluid system. Relatively little is known about the fluid properties in this system. However, the two primary fluids of interest, amniotic fluid and vernix caseosa, likely play integral roles in the force transferred to the fetus during the final stages of parturition. This investigation probes the role of fluid in the force transfer during delivery by considering physical models that determine the role of various components of the full system. The first experimental model represents the fetus passing through the birth canal as concentric cylinders with a fluid filled gap. The rigid, inner cylinder moves through the highly flexible outer cylinder at a prescribed velocity. The geometry of the inner cylinder is varied by aspect ratio and length. A total of five different inner geometries are used to fully investigate the parameter space. As the inner cylinder moves through the outer cylinder, strain measurements are taken. These measurements are converted to force measurements as a function of time and position in the outer cylinder. The results of these experiments are compared with numerical results to form a more complete picture of force transfer. This model can be used as the foundation for predicting the force needed to deliver a fetus in the final stages of parturition. Additionally, more complex models, that incorporate uterine contraction forces, are being developed.

  3. Experimental Studies of Mars-Analog Brines

    NASA Technical Reports Server (NTRS)

    Moore, Jeffrey M.; Bullock, Mark A.

    1999-01-01

    Evaporite deposits may represent significant sinks of mobile cations (e.g., those of Ca, N, Mg, and Fe) and anions (e.g., those of C, N, S, and Cl) among the materials composing the Martian surface and upper crust. Carbon and nitrogen are especially interesting because of their role as atmospheric gases which can become incorporated into crustal rocks. However, the nature of evaporite precursor brines formed under Martian conditions is poorly understood. To date, only a very limited number of laboratory investigations have been reported which have any bearing on a better understanding of various processes related to brine or evaporite formation on Mars. Here we report on preliminary laboratory experiments that exposed igneous minerals analogous to those in Martian (Shergottites, Nakhlites, and Chassigny (SNC) group) meteorites to a simulated Martian atmosphere and pure, deoxygenated water. Analysis of the water over intervals of time approaching 1 year showed that atmospheric gases dissolved to form carbonate and nitrate ions while minerals dissolved to form sulfate and chloride along with various cations. On an annual basis, ion formation gave a carbonate/sulfate ratio that is comparable to the ratio found among salts in SNC meteorites. The sulfate/chloride ratio of the experimental brines is higher than in SNC meteorites but lower than in surface soils measured at the Viking and Pathfinder landing sites.

  4. EXPERIMENTAL METHODOLOGIES AND PRELIMINARY TRANSFER FACTOR DATA FOR ESTIMATION OF DERMAL EXPOSURES TO PARTICLES

    EPA Science Inventory

    Developmental efforts and experimental data are described that focused on quantifying the transfer of particles on a mass basis from indoor surfaces to human skin. Methods were developed that utilized a common fluorescein-tagged Arizona Test Dust (ATD) as a possible surrogate ...

  5. EXPERIMENTAL METHODOLOGIES AND PRELIMINARY TRANSFER FACTOR DATA FOR ESTIMATION OF DERMAL EXPOSURES TO PARTICLES

    EPA Science Inventory

    Developmental efforts and experimental data are described that focused on quantifying the transfer of particles on a mass basis from indoor surfaces to human skin. Methods were developed that utilized a common fluorescein-tagged Arizona Test Dust (ATD) as a possible surrogate ...

  6. Exposure-response relationships between occupational exposures and chronic respiratory illness: a community-based study.

    PubMed

    Xu, X; Christiani, D C; Dockery, D W; Wang, L

    1992-08-01

    Data from a random sample of 3,606 adults 40 to 69 yr of age residing in Beijing, China, were analyzed to investigate the association of reported occupational exposures to dusts and gases/fumes with the prevalence of chronic respiratory symptoms and level of pulmonary function. The prevalence of occupational dust exposure was 32%, and gas or fume exposure, 19%. After we adjusted for age, sex, area of residence, smoking status, coal stove heating, and education, an increased prevalence of chronic phlegm and breathlessness was significantly related to both types of exposures. Chronic cough was significantly related only to dust exposure, and persistent wheeze only to fume exposure. The global estimates of the relative odds of the four symptoms were 1.30 (95% CI [confidence interval] 1.09 to 1.48) and 1.27 (95% CI 1.09 to 1.48), respectively, for dusts and for gases/fumes. These two occupational exposures are associated with chronic respiratory symptoms independent of smoking, gender, and each other. There was an increasing prevalence of each symptom with increasing dust and fume exposure, represented by the index of cumulative exposure duration and exposure intensity. Linear trends for increased prevalence of chron