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Sample records for intense field exposure

  1. Analyzing Exposures to Electromagnetic Fields in an Intensive Care Unit

    PubMed Central

    Gökmen, Necati; Erdem, Sabri; Toker, Kadir Atilla; Öçmen, Elvan; Gökmen, Başak Ilgım; Özkurt, Ahmet

    2016-01-01

    Objective In this study, we conducted a numerical analysis of exposure to electromagnetic fields (EMFs) in a hospital’s intensive care unit that is one of the most crucial one in terms of hazardous areas among all service units. This is a new study for measuring exposure to EMFs in an intensive care unit as well as other healthcare services in Turkey. Methods We measured the EMFs in the intensive care unit with a SRM-3006 (selective radiation metre), which was used for measurement of the absolute and the limit values of high frequency EMFs. The measurement points were chosen to represent the highest levels of exposure to which a person might be subjected. We obtained a dataset that included 5929 observations, with 96 extreme values, through measuring the magnetic field in terms of V/m. Results The measurements show the frequency varies from 47 MHz to 2.5 GHz as 17 frequency ranges at the measurement point as well. According to these findings, the referenced maximum safety limit was not exceeded. However, it was also found that mobile telecommunication was the most critical cause of magnetic fields. Conclusion Further studies need to be performed with different frequency antennas to assess the EMFs in intensive care units. PMID:27909603

  2. Out-of-Field Cell Survival Following Exposure to Intensity-Modulated Radiation Fields

    SciTech Connect

    Butterworth, Karl T.; McGarry, Conor K.; Trainor, Colman; O'Sullivan, Joe M.; Hounsell, Alan R.; Prise, Kevin M.

    2011-04-01

    Purpose: To determine the in-field and out-of-field cell survival of cells irradiated with either primary field or scattered radiation in the presence and absence of intercellular communication. Methods and Materials: Cell survival was determined by clonogenic assay in human prostate cancer (DU145) and primary fibroblast (AGO1552) cells following exposure to different field configurations delivered using a 6-MV photon beam produced with a Varian linear accelerator. Results: Nonuniform dose distributions were delivered using a multileaf collimator (MLC) in which half of the cell population was shielded. Clonogenic survival in the shielded region was significantly lower than that predicted from the linear quadratic model. In both cell lines, the out-of-field responses appeared to saturate at 40%-50% survival at a scattered dose of 0.70 Gy in DU-145 cells and 0.24 Gy in AGO1522 cells. There was an approximately eightfold difference in the initial slopes of the out-of-field response compared with the {alpha}-component of the uniform field response. In contrast, cells in the exposed part of the field showed increased survival. These observations were abrogated by direct physical inhibition of cellular communication and by the addition of the inducible nitric oxide synthase inhibitor aminoguanidine known to inhibit intercellular bystander effects. Additional studies showed the proportion of cells irradiated and dose delivered to the shielded and exposed regions of the field to impact on response. Conclusions: These data demonstrate out-of-field effects as important determinants of cell survival following exposure to modulated irradiation fields with cellular communication between differentially irradiated cell populations playing an important role. Validation of these observations in additional cell models may facilitate the refinement of existing radiobiological models and the observations considered important determinants of cell survival.

  3. Sinusoidal 50-Hz magnetic fields depress rat pineal NAT activity and serum melatonin. Role of duration and intensity of exposure.

    PubMed

    Selmaoui, B; Touitou, Y

    1995-01-01

    The purpose of this study was to determine whether the exposure to a 50-Hz sinusoidal magnetic field could influence serum melatonin concentration and pineal enzymes activities in rats. The effects of both duration and intensity of exposure were also looked at. Two groups of Wistar male rats were exposed to 50-Hz magnetic fields of either 1, 10 or 100 microT. The first group was exposed for 12 hours and the second for 30 days (18 hours per day). During this time the animals were kept under a standard 12:12 light: dark cycle with a temperature of 25 degrees C and a relative humidity of 45 to 50%. Control (Sham-exposed) animals were kept in a similar environment but without exposure to a magnetic field. The animals were sacrificed under red dim light. Serum melatonin concentration and pineal N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT) activities were studied. Long-term exposure to a magnetic field (10 and 100 microT) significantly depressed the nocturne peak of serum melatonin concentration and pineal NAT activity whereas no effect was observed on HIOMT activity. Short-term exposure depressed both pineal NAT activity and nocturnal serum melatonin concentration but only with the highest intensity used (100 microT). Our results suggest that sinusoidal magnetic fields alter the production of melatonin through an inhibition of pineal NAT activity. Both duration and intensity of exposure play an important role in this effect. This work shows that, 1) sinusoidal magnetic field depresses NAT activity as static magnetic field does whereas HIOMT activity remains unaltered whatever the type of experiment and the intensity used, 2) the effect observed is related to both the duration of exposure and the intensity of magnetic fields, 3) the sensitivity threshold to magnetic fields vary with the duration of exposure which strongly suggests a cumulative effect of sinusoidal magnetic fields on pineal function.

  4. High-intensity static magnetic field exposure devices for in vitro experiments on biopharmaceutical plant factories in aerospace environments.

    PubMed

    Lopresto, Vanni; Merla, Caterina; Pinto, Rosanna; Benvenuto, Eugenio

    2015-08-01

    Three high-intensity static magnetic field (SMF) exposure devices have been designed and realized for application to in vitro experimental research on hairy root cultures, supposed to grow in extreme environments- as those of space aircrafts- for producing biopharmaceutical molecules. The devices allow the exposure at two different levels of induction magnetic (B) field (250 mT and 500 mT) plus sham for blind exposure. The exposure levels can be considered representative of possible B-fields experienced within the habitat of a spacecraft in presence of active magnetic shielding systems. Each device can house a single 85-mm diameter Petri dish. Numerical simulations have been performed to accurately evaluate the B-field distribution in the biological target. Numerical results have been confirmed by measured data, proving that designed setups allows exposure to SMFs with a homogeneity better than 90%. The exposure devices will be employed for experiments scheduled within BIOxTREME research project, funded by the Italian Space Agency (ASI).

  5. [Bioeffects of chronic exposure to radiofrequency electromagnetic fields of low intensity (standardization strategy)].

    PubMed

    Grigor'ev, Iu G; Shafirkin, A V; Vasin, A L

    2003-01-01

    A retrospective analysis of the experimental researches on the effect of radio frequency electromagnetic fields (EMF) on human health, carried out in the USSR, is presented. The results of chronic exposure of laboratory animals to EMF have been considered. Apparently, EMF in the range of 1750-2750 MHz with power density up to 100-500 W/cm2 caused in immune globullin fractions, and a development of autoimmune processes. The changes in parameters of reproductive functions and posterity, the increase in embryo mortality were found. The standartization strategy used in the USSR and currently applied in Russia has been discussed.

  6. Impact of fractionation on out-of-field survival and DNA damage responses following exposure to intensity modulated radiation fields

    NASA Astrophysics Data System (ADS)

    Ghita, Mihaela; Coffey, Caroline B.; Butterworth, Karl T.; McMahon, Stephen J.; Schettino, Giuseppe; Prise, Kevin M.

    2016-01-01

    To limit toxicity to normal tissues adjacent to the target tumour volume, radiotherapy is delivered using fractionated regimes whereby the total prescribed dose is given as a series of sequential smaller doses separated by specific time intervals. The impact of fractionation on out-of-field survival and DNA damage responses was determined in AGO-1522 primary human fibroblasts and MCF-7 breast tumour cells using uniform and modulated exposures delivered using a 225 kVp x-ray source. Responses to fractionated schedules (two equal fractions delivered with time intervals from 4 h to 48 h) were compared to those following acute exposures. Cell survival and DNA damage repair measurements indicate that cellular responses to fractionated non-uniform exposures differ from those seen in uniform exposures for the investigated cell lines. Specifically, there is a consistent lack of repair observed in the out-of-field populations during intervals between fractions, confirming the importance of cell signalling to out-of-field responses in a fractionated radiation schedule, and this needs to be confirmed for a wider range of cell lines and conditions.

  7. Impact of fractionation on out-of-field survival and DNA damage responses following exposure to intensity modulated radiation fields.

    PubMed

    Ghita, Mihaela; Coffey, Caroline B; Butterworth, Karl T; McMahon, Stephen J; Schettino, Giuseppe; Prise, Kevin M

    2016-01-21

    To limit toxicity to normal tissues adjacent to the target tumour volume, radiotherapy is delivered using fractionated regimes whereby the total prescribed dose is given as a series of sequential smaller doses separated by specific time intervals. The impact of fractionation on out-of-field survival and DNA damage responses was determined in AGO-1522 primary human fibroblasts and MCF-7 breast tumour cells using uniform and modulated exposures delivered using a 225 kVp x-ray source. Responses to fractionated schedules (two equal fractions delivered with time intervals from 4 h to 48 h) were compared to those following acute exposures. Cell survival and DNA damage repair measurements indicate that cellular responses to fractionated non-uniform exposures differ from those seen in uniform exposures for the investigated cell lines. Specifically, there is a consistent lack of repair observed in the out-of-field populations during intervals between fractions, confirming the importance of cell signalling to out-of-field responses in a fractionated radiation schedule, and this needs to be confirmed for a wider range of cell lines and conditions.

  8. Depletion of Intense Fields

    NASA Astrophysics Data System (ADS)

    Seipt, D.; Heinzl, T.; Marklund, M.; Bulanov, S. S.

    2017-04-01

    The interaction of charged particles and photons with intense electromagnetic fields gives rise to multiphoton Compton and Breit-Wheeler processes. These are usually described in the framework of the external field approximation, where the electromagnetic field is assumed to have infinite energy. However, the multiphoton nature of these processes implies the absorption of a significant number of photons, which scales as the external field amplitude cubed. As a result, the interaction of a highly charged electron bunch with an intense laser pulse can lead to significant depletion of the laser pulse energy, thus rendering the external field approximation invalid. We provide relevant estimates for this depletion and find it to become important in the interaction between fields of amplitude a0˜1 03 and electron bunches with charges of the order of 10 nC.

  9. Depletion of intense fields

    NASA Astrophysics Data System (ADS)

    Bulanov, S. S.; Seipt, D.; Heinzl, T.; Marklund, M.

    2017-03-01

    The problem of backreaction of quantum processes on the properties of the background field still remains on the list of outstanding questions of high intensity particle physics. Usually, photon emission by an electron or positron, photon decay into electron-positron pairs in strong electromagnetic fields, or electron-positron pair production by such fields are described in the framework of the external field approximation. It is assumed that the external field has infinite energy and is not affected by these processes. However, the above-mentioned processes have a multi-photon nature, i.e., they occur with the absorption of a significant number of field photons. As a result, the interaction of an intense electromagnetic field with either a highly charged electron bunch or a fast growing population of electrons, positrons, and gamma photons (as in the case of an electromagnetic cascade) may lead to a depletion of the field energy, thus making the external field approximation invalid. Taking the multi-photon Compton process as an example, we estimate the threshold of depletion and find it to become significant at field strengths (a0˜103) and electron bunch charge of about tens of nC.

  10. Reactive oxygen species levels and DNA fragmentation on astrocytes in primary culture after acute exposure to low intensity microwave electromagnetic field.

    PubMed

    Campisi, Agata; Gulino, Marisa; Acquaviva, Rosaria; Bellia, Paolo; Raciti, Giuseppina; Grasso, Rosaria; Musumeci, Francesco; Vanella, Angelo; Triglia, Antonio

    2010-03-31

    The exposure of primary rat neocortical astroglial cell cultures to acute electromagnetic fields (EMF) in the microwave range was studied. Differentiated astroglial cell cultures at 14 days in vitro were exposed for 5, 10, or 20min to either 900MHz continuous waves or 900MHz waves modulated in amplitude at 50Hz using a sinusoidal waveform and 100% modulation index. The strength of the electric field (rms value) at the sample position was 10V/m. No change in cellular viability evaluated by MTT test and lactate dehydrogenase release was observed. A significant increase in ROS levels and DNA fragmentation was found only after exposure of the astrocytes to modulated EMF for 20min. No evident effects were detected when shorter time intervals or continuous waves were used. The irradiation conditions allowed the exclusion of any possible thermal effect. Our data demonstrate, for the first time, that even acute exposure to low intensity EMF induces ROS production and DNA fragmentation in astrocytes in primary cultures, which also represent the principal target of modulated EMF. Our findings also suggest the hypothesis that the effects could be due to hyperstimulation of the glutamate receptors, which play a crucial role in acute and chronic brain damage. Furthermore, the results show the importance of the amplitude modulation in the interaction between EMF and neocortical astrocytes.

  11. Multipole expansions and intense fields

    NASA Astrophysics Data System (ADS)

    Reiss, Howard R.

    1984-02-01

    In the context of two-body bound-state systems subjected to a plane-wave electromagnetic field, it is shown that high field intensity introduces a distinction between long-wavelength approximation and electric dipole approximation. This distinction is gauge dependent, since it is absent in Coulomb gauge, whereas in "completed" gauges of Göppert-Mayer type the presence of high field intensity makes electric quadrupole and magnetic dipole terms of importance equal to electric dipole at long wavelengths. Another consequence of high field intensity is that multipole expansions lose their utility in view of the equivalent importance of a number of low-order multipole terms and the appearance of large-magnitude terms which defy multipole categorization. This loss of the multipole expansion is gauge independent. Also gauge independent is another related consequence of high field intensity, which is the intimate coupling of center-of-mass and relative coordinate motions in a two-body system.

  12. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1995-10-17

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  13. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H.

    1994-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  14. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H.

    1995-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  15. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1994-08-16

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  16. Exposure guidelines for magnetic fields

    SciTech Connect

    Miller, G.

    1987-12-01

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

  17. Exposure guidelines for magnetic fields.

    PubMed

    Miller, G

    1987-12-01

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

  18. The effects of different intensities, frequencies and exposure times of extremely low-frequency electromagnetic fields on the growth of Staphylococcus aureus and Escherichia coli O157:H7.

    PubMed

    Bayır, Ece; Bilgi, Eyüp; Şendemir-Ürkmez, Aylin; Hameş-Kocabaş, E Esin

    2015-03-01

    The impact of different types of extremely low-frequency electromagnetic fields (ELF-EMF) on the growth of Staphylococcus aureus and Escherichia coli O157:H7 was investigated. The cultures of bacteria in broth media were exposed to sinusoidal homogenous ELF-EMF with 2 and 4 mT magnetic intensities. Each intensity for each bacteria was combined with three different frequencies (20, 40 and 50 Hz), and four different exposure times (1, 2, 4 and 6 h). A cell suspension of each experiment was diluted for the appropriate range and inoculated to Mueller-Hinton Agar (MHA) plates after exposure to ELF-EMF. The number of colony forming units (CFU) of both strains was obtained after incubation at 37 °C for 24 h. Data were statistically evaluated by one-way analysis of variance (ANOVA), statistical significance was described at p < 0.05 and data were compared with their non-exposed controls. Magnetic intensity, frequency and exposure time of ELF-EMFs changed the characteristic responses for both microorganisms. Samples exposed to ELF-EMF showed a statistically significant decrease compared to their controls in colony forming capability, especially at long exposure times. An exposure to 4 mT-20 Hz ELF-EMF of 6 h produced maximum inhibition of CFU compared to their controls for both microorganisms (95.2% for S. aureus and 85% for E. coli).

  19. Biological effects from electromagnetic field exposure and public exposure standards.

    PubMed

    Hardell, Lennart; Sage, Cindy

    2008-02-01

    During recent years there has been increasing public concern on potential health risks from power-frequency fields (extremely low frequency electromagnetic fields; ELF) and from radiofrequency/microwave radiation emissions (RF) from wireless communications. Non-thermal (low-intensity) biological effects have not been considered for regulation of microwave exposure, although numerous scientific reports indicate such effects. The BioInitiative Report is based on an international research and public policy initiative to give an overview of what is known of biological effects that occur at low-intensity electromagnetic fields (EMFs) exposure. Health endpoints reported to be associated with ELF and/or RF include childhood leukaemia, brain tumours, genotoxic effects, neurological effects and neurodegenerative diseases, immune system deregulation, allergic and inflammatory responses, breast cancer, miscarriage and some cardiovascular effects. The BioInitiative Report concluded that a reasonable suspicion of risk exists based on clear evidence of bioeffects at environmentally relevant levels, which, with prolonged exposures may reasonably be presumed to result in health impacts. Regarding ELF a new lower public safety limit for habitable space adjacent to all new or upgraded power lines and for all other new constructions should be applied. A new lower limit should also be used for existing habitable space for children and/or women who are pregnant. A precautionary limit should be adopted for outdoor, cumulative RF exposure and for cumulative indoor RF fields with considerably lower limits than existing guidelines, see the BioInitiative Report. The current guidelines for the US and European microwave exposure from mobile phones, for the brain are 1.6 W/Kg and 2 W/Kg, respectively. Since use of mobile phones is associated with an increased risk for brain tumour after 10 years, a new biologically based guideline is warranted. Other health impacts associated with exposure to

  20. Mechanism of biological effects observed in honey bees (Apis mellifera, L. ) hived under extra-high-voltage transmission lines: implications derived from bee exposure to simulated intense electric fields and shocks

    SciTech Connect

    Bindokas, V.P.; Gauger, J.R.; Greenberg, B.

    1988-01-01

    This work explores mechanisms for disturbance of honey bee colonies under a 765 kV, 60-Hz transmission line (electric (E) field = 7 kV/m) observed in previous studies. Proposed mechanisms fell into two categories: direct bee perception of enhanced in-hive E fields and perception of shock from induced currents. The adverse biological effects could be reproduced in simulations where only the worker bees were exposed to shock or to E field in elongated hive entranceways (= tunnels). We now report the results of full-scale experiments using the tunnel exposure scheme, which assesses the contribution of shock and intense E field to colony disturbance. Exposure of worker bees (1400 h) to 60-Hz E fields including 100 kV/m under moisture-free conditions within a nonconductive tunnel causes no deleterious affect on colony behavior. Exposure of bees in conductive (e.g., wet) tunnels produces bee disturbance, increased mortality, abnormal propolization, and possible impairment of colony growth. We propose that this substrate dependence of bee disturbance is the result of perception of shock from coupled body currents and enhanced current densities postulated to exist in the legs and thorax of bees on conductors. Similarly, disturbance occurs when bees are exposed to step-potential-induced currents. At 275-350 nA single bees are disturbed; at 600 nA bees begin abnormal propolization behavior; and stinging occurs at 900 nA. We conclude that biological effects seen in bee colonies under a transmission line are primarily the result of electric shock from induced hive currents. This evaluation is based on the limited effects of E-field exposure in tunnels, the observed disturbance thresholds caused by shocks in tunnels, and the ability of hives exposed under a transmission line to source currents 100-1,000 times the shock thresholds.

  1. Atoms in intense laser fields

    SciTech Connect

    Gavrila, M. )

    1992-01-01

    This book covers the following topics. Multiphoton ionization; photoionization with ultra-short laser pulses; Rydberg atoms in strong microwave fields; high-order harmonic generation in rare gases; mechanisms of short-wavelength generation; time-dependent studies of multiphoton processes; numerical experiments in strong and super-strong fields; resonance in multiphonton ionization nonpertubative treatment of multiphonton ionization within the floquet framework, atomic structure and decay in high frequency fields.

  2. [Noise exposure in neonatal intensive care units].

    PubMed

    Magnavita, V; Arslan, E; Benini, F

    1994-01-01

    This study evaluates the exposure of newborn babies in neonatal intensive care units (NICU) to noise which can cause hearing lesions directly (acoustic trauma) as well as indirectly (hypoxia). Moreover, noise can have an aggravating effect when combined with other potentially harmful factors in the NICU, such as ototoxic medication or stress due to other external stimuli, such as excessively bright light, lack of a day/night rhythm or pain. Sound pressure levels were measured in the NICU and inside the cribs in various experimental conditions, classified under 3 different types of sound events: constant background noise, variations in background noise and impulsive events. The main sources of noise detected were crib noise generated by ventilation and temperature control systems, ambient noise in the room, noise caused by the staff in the NICU, noise generated by crib alarm systems and NICU apparatus and noise caused by activity on the crib cover or on its plexiglas top. Findings revealed that the influence of ambient noise is fairly irrelevant. Background noise and its variations concerned with activities in the department never exceeded the limits considered potentially harmful to adults (DRC), whereas the impulsive noise generated by staff on the cribs or on the plexiglas tops was considerable and potentially harmful. These findings demonstrate that it is feasible and relatively easy to control noise in the NICU and significantly reduce the impulsive noise component by training staff to be more careful and avoid any unnecessary jolting and rough handling on and near the cribs.

  3. Gauges for intense-field electrodynamics

    NASA Astrophysics Data System (ADS)

    Reiss, Howard R.

    1980-08-01

    For all gauges of the Göppert-Mayer type, the two-body Schrödinger equation for charged particles in a plane-wave electromagnetic field fails to separate into center-of-mass and relative-coordinate equations when the field is sufficiently intense.

  4. Intense Terahertz Fields for Fast Energy Release

    DTIC Science & Technology

    2016-11-01

    6201 Fort Belvoir, VA 22060-6201 T E C H N IC A L R E P O R T DTRA-TR-17-10 Intense Terahertz Fields for Fast Energy Release...N) Energy /Work/Power electron volt (eV) 1.602 177 × 10 –19 joule (J) erg 1 × 10 –7 joule (J) kiloton (kt) (TNT equivalent) 4.184 × 10 12...customary unit. Grant #  HDTRA 1-12-1-0044 Intense Terahertz Fields for Fast Energy Release Final Report PI: Keith A. Nelson 617-253-1423 kanelson

  5. Assessment of exposure to magnetic fields in occupational settings.

    PubMed

    Sakurazawa, Hirofumi; Iwasaki, Akio; Higashi, Toshiaki; Nakayama, Takeo; Kusaka, Yukinori

    2003-03-01

    It is important to have data about occupational magnetic field intensity to consider the contribution of occupational magnetic field exposure on the human body. We conducted research on exposure to occupational magnetic fields and tried to qualify data on the distribution of magnetic field' intensity in certain general working environments with individual measurements. We performed sample research on the exposure to low-frequency magnetic fields of workers in certain occupations and in the working environment. We also assessed the relationship between working environmental magnetic field distribution and individual exposure. Some occupations were found to be exposed to high magnetic fields. We observed that some workspaces, such as the transformer substation, generally had a uniform and high magnetic field measurement but employees were exposed to a lower intensity. We also found that welders were exposed to high magnetic fields at about 600 microT in a very short time but with a geometrical value of 0.08 microT. The determination of administrative levels and control levels, not only of the time weighted average of threshold limits or short term exposure limits, but also ceiling limits should be considered. More systematic research is necessary to determine variables such as operating conditions, measuring position, and frequency bands. Also, further studies will be needed to make a job-exposure matrix for the magnetic fields for each occupation type and to combine it with exposure in non-occupational settings such as commuting and ordinary life situations to explore the causal relationship between exposure to magnetic fields and disease.

  6. The NASA High Intensity Radiated Fields Laboratory

    NASA Technical Reports Server (NTRS)

    Williams, Reuben A.

    1997-01-01

    High Intensity Radiated Fields (HIRF) are the result of a multitude of intentional and nonintentional electromagnetic sources that currently exists in the world. Many of today's digital systems are susceptible to electronic upset if subjected to certain electromagnetic environments (EME). Modern aerospace designers and manufacturers increasingly rely on sophisticated digital electronic systems to provide critical flight control in both military, commercial, and general aviation aircraft. In an effort to understand and emulate the undesired environment that high energy RF provides modern electronics, the Electromagnetics Research Branch (ERB) of the Flight Electronics and Technology Division (FETD) conducts research on RF and microwave measurement methods related to the understanding of HIRF. In the High Intensity Radiated Fields Laboratory, the effects of high energy radiating electromagnetic fields on avionics and electronic systems are tested and studied.

  7. Radiation reaction in high-intensity fields

    NASA Astrophysics Data System (ADS)

    Seto, Keita

    2015-10-01

    Since the development of a radiating electron model by Dirac in 1938 [P. A. M. Dirac, Proc. R. Soc. Lond. A 167, 148 (1938)], many authors have tried to reformulate this model of the so-called "radiation reaction". Recently, this effect has become important in ultra-intense laser-electron (plasma) interactions. In our recent research, we found a way of stabilizing the radiation reaction by quantum electrodynamics (QED) vacuum fluctuation [K Seto et al., Prog. Theor. Exp. Phys. 2014, 043A01 (2014); K. Seto, Prog. Theor. Exp. Phys. 2015, 023A01 (2015)]. On the other hand, the modification of the radiated field by highly intense incoming laser fields should be taken into account when the laser intensity is higher than 10^{22} W/cm2, which could be achieved by next-generation ultra-short-pulse 10 PW lasers, like the ones under construction for the ELI-NP facility. In this paper, I propose a running charge-mass method for the description of the QED-based synchrotron radiation by high-intensity external fields with stabilization by the QED vacuum fluctuation as an extension from the model by Dirac.

  8. Orienting Paramecium with intense static magnetic fields

    NASA Astrophysics Data System (ADS)

    Valles, James M., Jr.; Guevorkian, Karine; Quindel, Carl

    2004-03-01

    Recent experiments on cell division suggest the application of intense static magnetic fields as a novel tool for the manipulation of biological systems [1]. The magnetic field appears to couple to the intrinsic anisotropies in the diamagnetic components of the cells. Here, we present measurements of the intrinsic average diamagnetic anisotropy of the whole single celled ciliate, Paramecium Caudatum. Magnetic fields, 2.5 T < B < 8 T were applied to immobilized (non-swimming) Paramecium Caudatum that were suspended in a density matched medium. The organisms align with their long axis parallel to the applied magnetic field. Their intrinsic diamagnetic anisotropy is 3x10-11 in cgs units. We will discuss the implications of these results for employing magnetic fields to probe the behavior of swimming Paramecium. [1] J. M. Valles, Jr. et al., Expt. Cell Res.274, 112-118 (2002).

  9. Abnormal environmental light exposure in the intensive care environment.

    PubMed

    Fan, Emily P; Abbott, Sabra M; Reid, Kathryn J; Zee, Phyllis C; Maas, Matthew B

    2017-08-01

    We sought to characterize ambient light exposure in the intensive care unit (ICU) environment to identify patterns of light exposure relevant to circadian regulation. A light monitor was affixed to subjects' bed at eye level in a modern intensive care unit and continuously recorded illuminescence for at least 24h per subject. Blood was sampled hourly and measured for plasma melatonin. Subjects underwent hourly vital sign and bedside neurologic assessments. Care protocols and the ICU environment were not modified for the study. A total of 67,324 30-second epochs of light data were collected from 17 subjects. Light intensity peaked in the late morning, median 64.1 (interquartile range 19.7-138.7) lux. The 75th percentile of light intensity exceeded 100lx only between 9AM and noon, and never exceeded 150lx. There was no correlation between melatonin amplitude and daytime, nighttime or total light exposure (Spearman's correlation coefficients all <0.2 and p>0.5). Patients' environmental light exposure in the intensive care unit is consistently low and follows a diurnal pattern. No effect of nighttime light exposure was observed on melatonin secretion. Inadequate daytime light exposure in the ICU may contribute to abnormal circadian rhythms. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Ongoing exposure versus intense periodic exposure to military conflict and terror attacks in Israel.

    PubMed

    Lahad, Mooli; Leykin, Dmitry

    2010-12-01

    The manifestation of posttraumatic stress disorder (PTSD) symptoms in two clinical samples in Israel (N = 212) was examined. Individuals suffering ongoing exposure to shelling were compared with subjects exposed to intense periodic exposure. Elevated arousal and avoidance symptoms, but not intrusion were reported in the ongoing exposure group. When compared by age, young participants in the ongoing exposure group had significantly lower PTSD scores, whereas no differences were found between participants among the intense periodic exposure age groups. No gender differences in symptoms were found among participants from intense periodic exposure, whereas in the other ongoing group the difference was in avoidance. Results are discussed in light of past research on exposure to terrorism. Copyright © 2010 International Society for Traumatic Stress Studies.

  11. [Clinical monitoring in areas of exposure to radiofrequency electromagnetic fields].

    PubMed

    Suvorov, I M

    2013-01-01

    Clinical syndromes induced by high intensity radiofrequency electromagnetic field chronic exposure are described. Persons injured by occupational exposure have been observed central nervous system changes in diencephalic syndrome form, cardio-vascular system changes revealed in atherosclerosis, isch(a)emic heart disease and coronary insufficiency rapid progressive expansion. General public living in territory of radar station exposure zone different functional disorders have been identified: vegetative dystonia (asthenovegetative syndrome), thrombocytopenia, decrease of blood coagulation index, and thyroid gland function changes. Observed diseases clinical variability may be determined by electromagnetic exposure characteristics.

  12. Intensity of exposure and incidence of melioidosis in Thai children.

    PubMed

    Cheng, Allen C; Wuthiekanun, Vanaporn; Limmathurotsakul, Direk; Chierakul, Wirongrong; Peacock, Sharon J

    2008-12-01

    There is a high background seroprevalence of antibodies to Burkholderia pseudomallei in Thailand that limits its use as a diagnostic tool. It is believed that this results from childhood exposure to the bacterium in mud and surface water. The increasing prevalence of antibodies with age is a marker of the intensity of exposure. A susceptible-infected-susceptible (SIS) model was calibrated with data on seroprevalence in children (<15 years) in Udon Thani and Ubon Ratchathani (n=2214). In this mathematical model, children were assumed to gain antibodies at a constant rate related to exposure events, and waning antibody response occurred at a constant rate. The intensity of exposure appeared to be higher in Udon Thani than in Ubon Ratchathani, with 24% vs. 11% of patients becoming seropositive each year. In Udon Thani children, antibodies appeared to be long-lasting, compared with those in Ubon Ratchathani, where the mean duration was 5.2 years. Based on an estimated paediatric disease incidence in Ubon Ratchathani of 4.15 per 100,000 population, it is estimated that approximately 1 in 4600 antibody-producing exposures results in clinical infection. Childhood seroprevalence can be used as a marker of intensity of exposure. Further work to separate the effect of exposure to B. thailandensis and cross-reactivity to B. pseudomallei is proposed.

  13. Atomic electron correlations in intense laser fields

    SciTech Connect

    Agostini, P A; DiMauro, L F; Kulander, K; Sheehy, B; Walker, B

    1998-09-03

    Abstract. This talk examines two distinct cases in strong opbical fields where electron correlation plays an important role in the dynamic.s. In the first. example, strong coupling in a two-electron-like system is manifested as an intensity-dependent splitting in the ionized electron energy distribution. This two-electron phenomenon (dubbed continuum-continuum Autler-Townes effect) is analogous to a strongly coupled two- level, one-electron atom but raises some intriguing questions regarding the exact nature of electron-electron correlation. The second case examines the evidence for two-electron ionization in the strong-field tunneling limit. Although our ability to describe the one- electron dynamics has obtained a quantitative level of understanding, a description of the two (multiple) electron ionization remains unc

  14. Atomic electron correlations in intense laser fields

    SciTech Connect

    DiMauro, L.F.; Sheehy, B.; Walker, B. Agostini, P.A. Kulander, K.C.

    1999-06-01

    This talk examines two distinct cases in strong optical fields where electron correlation plays an important role in the dynamics. In the first example, strong coupling in a two-electron-like system is manifested as an intensity-dependent splitting in the ionized electron energy distribution. This two-electron phenomenon (dubbed continuum-continuum Autler-Townes effect) is analogous to a strongly coupled two-level, one-electron atom but raises some intriguing questions regarding the exact nature of electron-electron correlation. The second case examines the evidence for two-electron ionization in the strong-field tunneling limit. Although our ability to describe the one-electron dynamics has obtained a quantitative level of understanding, a description of the two (multiple) electron ionization remains unclear. {copyright} {ital 1999 American Institute of Physics.}

  15. Atomic electron correlations in intense laser fields

    SciTech Connect

    DiMauro, L.F.; Sheehy, B.; Walker, B.; Agostini, P.A.; Kulander, K.C.

    1998-11-01

    This talk examines two distinct cases in strong optical fields where electron correlation plays an important role in the dynamics. In the first example, strong coupling in a two-electron-like system is manifested as an intensity-dependent splitting in the ionized electron energy distribution. This two-electron phenomenon (dubbed continuum-continuum Autler-Townes effect) is analogous to a strongly coupled two-level, one-electron atom but raises some intriguing questions regarding the exact nature of electron-electron correlation. The second case examines the evidence for two-electron ionization in the strong-field tunneling limit. Although their ability to describe the one-electron dynamics has obtained a quantitative level of understanding, a description of the two (multiple) electron ionization remains unclear.

  16. Atomic electron correlations in intense laser fields

    SciTech Connect

    DiMauro, L. F.; Sheehy, B.; Walker, B.; Agostini, P. A.; Kulander, K. C.

    1999-06-11

    This talk examines two distinct cases in strong optical fields where electron correlation plays an important role in the dynamics. In the first example, strong coupling in a two-electron-like system is manifested as an intensity-dependent splitting in the ionized electron energy distribution. This two-electron phenomenon (dubbed continuum-continuum Autler-Townes effect) is analogous to a strongly coupled two-level, one-electron atom but raises some intriguing questions regarding the exact nature of electron-electron correlation. The second case examines the evidence for two-electron ionization in the strong-field tunneling limit. Although our ability to describe the one-electron dynamics has obtained a quantitative level of understanding, a description of the two (multiple) electron ionization remains unclear.

  17. Proterozoic Geomagnetic Field: Intensity, Morphology and Stability

    NASA Astrophysics Data System (ADS)

    Smirnov, A. V.

    2007-12-01

    Information about the geometry, stability, and intensity of Earth's magnetic field during the Proterozoic is of great importance for understanding the early geodynamo and in the interpretation of paleomagnetic data with regards to paleogeographic reconstructions, true polar wander, global glaciations and other problems. What are the space-time characteristics of the Proterozoic field, such as the relative significance of the dipole and non-dipole components, and are these characteristics significantly different from their Phanerozoic counterparts? In the absence of strict theoretical constraints, paleomagnetic data are the principal source of information about the Precambrian field. Field geometry can be estimated by combining paleomagnetic data with independent latitudinal indicators such as evaporites and glacial deposits. A hotter Precambrian Earth coupled with absence of the inner core could have resulted in higher field variation, including more frequent reversals. The current magnetostratigraphic database is insufficient to test whether the early geodynamo reversed its polarity with the same range of frequencies as in the Mesozoic-Cenozoic interval. However, Precambrian rocks may preserve directional information useful for constraining paleosecular variation (PSV). The estimates of PSV based on the Precambrian paleomagnetic database will be discussed. Paleointensity data provide information on the energy state of geodynamo and may prove crucial for constraining models of the thermal evolution of the Earth (e.g., the timing of nucleation and growth of the solid inner core). However, many Precambrian rock sequences have been affected by alteration, which hinders the measurement of paleointensity using bulk rock samples. In addition, many paleointensity determinations for that time period come from intrusive rocks in which the paleointensity signal may be complicated by thermochemical remanent magnetization and other factors. Therefore, a caution should be

  18. A Template for an Intensive Ecohydrology Field Course

    NASA Astrophysics Data System (ADS)

    Emanuel, R. E.; McGlynn, B. L.; Riveros-Iregui, D. A.

    2014-12-01

    Many of the greatest challenges in the earth and environmental sciences are complex and interdisciplinary in nature. Ecohydrology exemplifies the type of holistic inquiry needed to address these challenges because it spans and integrates earth science, biological science and, often, social science. Ecohydrology courses can prepare the next generation of scientists, decision-makers and informed citizens to understand and address these challenges, and field courses in particular can play an important role in this preparation. Ecohydrology field course instructors have unique opportunities to convey interwoven theoretical and applied principles through a variety of modes that include lecture, discussion, immersion, and hands-on activity. In this presentation, we report on our experience co-teaching the Mountain Ecohydrology Field Course, a full-credit course taught 3 times in the past 5 years to more than 30 students representing 6 universities. The course, which has ranged from 1-2 weeks in length, has given students in-depth exposure to intensively instrumented ecohydrological field sites in the southern Appalachian and northern Rocky Mountains. Students learn fundamental principles in ecohydrology and related fields of watershed hydrology, soil biogeochemistry, micrometeorology and plant ecophysiology. They gain hands-on experience in a variety of cutting edge field techniques, tools and analyses while practicing presentation and communication of science. Students and instructors deal with real-world challenges of conducting fieldwork in remote settings. We offer our experience as one potential template for others interested in developing or refining ecohydrology field courses elsewhere.

  19. Real exposure: field measurement of chemical plumes in headwater streams.

    PubMed

    Edwards, David D; Moore, Paul A

    2014-10-01

    In fluvial systems, organismic exposure to nonpoint source pollutants will fluctuate in frequency (exposure events), intensity (concentration), and duration. The reliance on lethal concentrations and static exposure in many laboratory studies does not adequately represent nor address exposure to in situ chemical plumes of fluvial habitats. To adequately address field exposure in a laboratory setting, one needs an understanding of the physics of chemical transmission within moving fluids. Because of the chaotic nature of turbulence, chemical plumes introduced to fluvial systems have a spatial and temporal microstructure with fluxes in chemical concentration. Consequently, time-averaged static exposure models are not ecologically relevant for the major reason of in situ distribution. The purpose of this study was to quantify in situ chemical distribution and dispersion within two physically different streams. Dopamine was introduced as a chemical tracer mimicking groundwater runoff. Chemical fluxes and stream hydrodynamics were simultaneously measured using a microelectrode and an acoustic Doppler velocimeter, respectively, at three heights of three downstream locations at each research site. Fine-scale measurements of the dopamine plume microstructure showed that organisms could be exposed to chemical fluctuations where concentrations are significantly greater than the overall time-averaged concentration. These measurements demonstrate that rather than relying on static exposure, standards for pollution must consider the concept of exposure being interdependently linked to flow of the fluid medium. The relationship between fluid dynamics, pollution exposure, and organism physiology are complex and must be evaluated in ways to mimic natural systems.

  20. Real exposure: Field measurement of chemical plumes in headwater streams

    NASA Astrophysics Data System (ADS)

    Edwards, David D.

    In fluvial systems, organismic exposure to nonpoint source pollutants will fluctuate in frequency (exposure events), intensity (concentration), and duration. The reliance on lethal concentrations and static exposure in many laboratory studies does not adequately represent nor address exposure to in situ chemical plumes of fluvial habitats. In order to adequately address field exposure in a lab setting, one needs an understanding of the physics of chemical transmission within moving fluids. Because of the chaotic nature of turbulence, chemical plumes introduced to fluvial systems have a spatial and temporal microstructure with fluxes in chemical concentration. Consequently, time-averaged static exposure models are not ecologically relevant for the major reason of in situ distribution. The purpose of this study was to quantify in situ chemical distribution and dispersion within two physically different streams. Dopamine was introduced as a chemical tracer mimicking groundwater runoff. Chemical fluxes and stream hydrodynamics were simultaneously measured using a microelectrode and an acoustic doppler velocimeter (ADV), respectively, at three heights of three downstream locations at each research site. Fine-scale measurements of the dopamine plume microstructure showed organisms could be exposed to chemical fluctuations where concentrations are significantly greater than the overall time-averaged concentration. These measurements demonstrate that rather than relying on static exposure, standards for pollution need to consider the concept of exposure being interdependently linked to flow of the fluid medium. The relationship between fluid dynamics, pollution exposure and organism physiology are complex and need to be evaluated in ways to mimic natural systems.

  1. Human melatonin during continuous magnetic field exposure

    SciTech Connect

    Graham, C.; Cook, M.R.; Riffle, D.W.

    1997-05-01

    This report describes the third in a series of double-blind, laboratory-based studies that were aimed at determining the effects of nocturnal exposure to power frequency magnetic fields on blood levels of melatonin in human volunteers. The two earlier studies evaluated effects on melatonin of intermittent exposure to 60 Hz circularly polarized magnetic fields at 10 and 200 mG. No overall effects on melatonin levels were found. In the present study, men were exposed continuously rather than intermittently through the night to the same 200 mG magnetic field condition that was used previously; again, no overall effects on melatonin levels were found. The authors conclude that the intermittent and continuous exposure conditions used in the laboratory to date are not effective in altering nocturnal blood levels of melatonin in human volunteers.

  2. Assessment of inhomogeneous ELF magnetic field exposures.

    PubMed

    Leitgeb, N; Cech, R; Schröttner, J

    2008-01-01

    In daily life as well as at workplaces, exposures to inhomogeneous magnetic fields become very frequent. This makes easily applicable compliance assessment methods increasingly important. Reference levels have been defined linking basic restrictions to levels of homogeneous fields at worst-case exposure conditions. If reference levels are met, compliance with basic restrictions can be assumed. If not, further investigations could still prove compliance. Because of the lower induction efficiency, inhomogeneous magnetic fields such as from electric appliances could be allowed exceeding reference levels. To easily assess inhomogeneous magnetic fields, a quick and flexible multi-step assessment procedure is proposed. On the basis of simulations with numerical, anatomical human models reference factors were calculated elevating reference levels to link hot-spot values measured at source surfaces to basic limits and allowing accounting for different source distance, size, orientation and position. Compliance rules are proposed minimising assessment efforts.

  3. Chlorpyrifos exposures in Egyptian cotton field workers.

    PubMed

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

    2010-06-01

    Neurobehavioral deficits have been reported in Egyptian pesticide application teams using organophosphorus (OP) pesticides, but whether these effects are related to OP pesticide exposures has yet to be established. In preparation for a comprehensive study of the relationship between OP pesticide dose and neurobehavioral deficits, we assessed exposure within this population. We conducted occupational surveys and workplace observations, and collected air, dermal patch and biological samples from applicators, technicians and engineers involved in chlorpyrifos applications during cotton production to test the hypotheses that: (1) dermal exposure was an important contributor to internal dose and varied across body regions; and (2) substantial differences would be seen across the three job categories. Applicators were substantially younger and had shorter exposure histories than did technicians and engineers. Applicators and technicians were observed to have relatively high levels of skin or clothing contact with pesticide-treated foliage as they walked through the fields. Both dermal patch loadings of chlorpyrifos and measurements of a chlorpyrifos-specific metabolite (TCPy) in urine confirmed substantial exposure to and skin absorption of chlorpyrifos that varied according to job category; and dermal patch loading was significantly higher on the thighs than on the forearms. These findings support our hypotheses and support the need for research to examine neurobehavioral performance and exposures in this population. More importantly, the exposures reported here are sufficiently high to recommend urgent changes in work practices amongst these workers.

  4. Low Caspofungin Exposure in Patients in Intensive Care Units.

    PubMed

    van der Elst, Kim C M; Veringa, Anette; Zijlstra, Jan G; Beishuizen, Albertus; Klont, Rob; Brummelhuis-Visser, Petra; Uges, Donald R A; Touw, Daan J; Kosterink, Jos G W; van der Werf, Tjip S; Alffenaar, Jan-Willem C

    2017-02-01

    In critically ill patients, drug exposure may be influenced by altered drug distribution and clearance. Earlier studies showed that the variability in caspofungin exposure was high in intensive care unit (ICU) patients. The primary objective of this study was to determine if the standard dose of caspofungin resulted in adequate exposure in critically ill patients. A multicenter prospective study in ICU patients with (suspected) invasive candidiasis was conducted in the Netherlands from November 2013 to October 2015. Patients received standard caspofungin treatment, and the exposure was determined on day 3 of treatment. An area under the concentration-time curve from 0 to 24 h (AUC0-24) of 98 mg · h/liter was considered adequate exposure. In case of low exposure (i.e., <79 mg · h/liter, a ≥20% lower AUC0-24), the caspofungin dose was increased and the exposure reevaluated. Twenty patients were included in the study, of whom 5 had a positive blood culture. The median caspofungin AUC0-24 at day 3 was 78 mg · h/liter (interquartile range [IQR], 69 to 97 mg · h/liter). A low AUC0-24 (<79 mg · h/liter) was seen in 10 patients. The AUC0-24 was significantly and positively correlated with the caspofungin dose in mg/kg/day (P = 0.011). The median AUC0-24 with a caspofungin dose of 1 mg/kg was estimated using a pharmacokinetic model and was 114.9 mg · h/liter (IQR, 103.2 to 143.5 mg · h/liter). In conclusion, the caspofungin exposure in ICU patients in this study was low compared with that in healthy volunteers and other (non)critically ill patients, most likely due to a larger volume of distribution. A weight-based dose regimen is probably more suitable for patients with substantially altered drug distribution. (This study has been registered at ClinicalTrials.gov under registration no. NCT01994096.).

  5. Remarks About Fields Of High Intensity

    SciTech Connect

    Teller, Edward

    1986-12-05

    At high field strength any known material will break down by the production of electrons and ions. At a higher field strength, massive production of pairs will occur. This phenomenon is discussed when heavy ions of Υ ≈ 100 collide.

  6. Wavelength and intensity effects on the dissociation of H2 + in intense laser fields

    NASA Astrophysics Data System (ADS)

    Hu, Hongtao; Xu, Han; Bai, Ya; Sang, R. T.; Litvinyuk, Igor V.; Liu, Peng; Li, Ruxin

    2016-11-01

    We report on a systematic investigation of the dissociation dynamics of H2 + in intense laser fields, and study how the kinetic energy spectrum of the dissociating proton can be modulated by the wavelength and intensity of the driving laser field. In the experiment, H2 is dissociatively ionized by an intense laser pulse with varying carrier wavelengths ranging from 800 to 1800 nm and varying peak intensities. A model based on Floquet theory and Landau-Zener theory is adopted to explain the experimental observations. The intensity effect is further explored in a few-cycle pump-probe experiment. We observed a significant intensity-dependent proton kinetic energy shift, which can also be well explained by the theoretical simulation. The wavelength- and intensity-dependent proton spectra reveal the mechanism of selective excitation of vibrational levels of H2 + in intense laser fields.

  7. Nonauditory effects of repeated exposures to intense impulse noise

    SciTech Connect

    Phillips, Y.Y.; Dancer, A.; Richmond, D.R.

    1986-01-01

    Exposure to intense impulse noise can cause injury to all of the air-containing structures of the body. While the ear is the most-sensitive organ, the upper respiratory tract (URT), the lungs, and the gut can be damaged by air blast. This nonauditory injury has been studied as a consequence of weapon-effects research. The development of light, long-range artillery and powerful shoulder-fired antitank weapons has increased the intensity of impulse noise to which soldiers are exposed. Hearing damage is recognized as a military occupational health hazard, and the advent of louder weapons has raised the possibility that nonauditory injury might become a limiting safety concern. Animal research was begun in Europe and the United States in an attempt to define that new hazard. Anesthetized sheep and swine were necropsied after being exposed to a variety of impulse conditions. It was readily demonstrated that with repeated exposures, nonauditory injury could build up at relatively low overpressure levels.

  8. Overview of occupational exposure to electric and magnetic fields and cancer: Advancements in exposure assessment

    SciTech Connect

    Savitz, D.A.

    1995-03-01

    For over ten years, there has been concern with the potential for increased risk of cancer among {open_quotes}electrical workers.{close_quotes} In contrast to studies of residential exposure to magnetic fields, occupational studies include electric and magnetic field exposures and have much greater variability in field intensity, frequency, and temporal patterns. Studies of leukemia in electrical workers show a moderate consistency, with elevated risk ratios of 1.2 to 2.0 commonly observed. Brain tumors are similarly elevated with some consistency, and three recent studies have suggested increased risk of male breast cancer. Retrospective exposure assessment methods were advanced in recent studies of diverse occupations in a study in central Sweden, which yielded evidence of increased risk of chronic lymphocytic leukemia among men in more highly exposed occupations. A study of telephone workers in New York State incorporated measurements and found some indication of increased leukemia risk only when exposures were based on historical technology. Utility workers in southern California were studied and found not to have increased risks of leukemia and brain cancer based on exposures estimated with measurements. An ongoing study of electric utility workers at five companies in the United States incorporates an extensive measurement protocol. Randomly selected workers within occupational categories wore a time integrating magnetic-field meter to provide estimates of exposure for the occupational category. We were able to estimate and partition the variance into between-day (the largest contributor), within occupational categories, and between occupational categories. Principal research needs concern optimal levels of worker aggregation for exposure assignment, historical extrapolation, study of diverse work environments, and integration of residential and occupational exposure in the same study. 19 refs., 1 tab.

  9. Paediatric intensive care in the field hospital.

    PubMed

    Harris, C C; McNicholas, J J K

    2009-06-01

    Our recent experience of paediatric critical care during UK military operations in Afghanistan is discussed alongside consideration of the background to the paediatric critical care service on deployment. We describe the intensive care unit's capabilities, details of recent paediatric critical care admissions during July to September 2008 and some of the ethical issues arising. Some desirable future developments will be suggested.

  10. 78 FR 33633 - Human Exposure to Radiofrequency Electromagnetic Fields

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-04

    ... to Radiofrequency Electromagnetic Fields; Reassessment of Exposure to Radiofrequency Electromagnetic..., and 95 Human Exposure to Radiofrequency Electromagnetic Fields AGENCY: Federal Communications... electromagnetic fields. More specifically, the Commission clarifies evaluation procedures and references...

  11. Enhancement of invertase production by Aspergillus niger OZ-3 using low-intensity static magnetic fields.

    PubMed

    Taskin, Mesut; Esim, Nevzat; Genisel, Mucip; Ortucu, Serkan; Hasenekoglu, Ismet; Canli, Ozden; Erdal, Serkan

    2013-01-01

    The aim of this study is to investigate the effect of low-intensity static magnetic fields (SMFs) on invertase activity and growth on different newly identified molds. The most positive effect of SMFs on invertase activity and growth was observed for Aspergillus niger OZ-3. The submerged production of invertase was performed with the spores obtained at the different exposure times (120, 144, 168, and 196 hr) and magnetic field intensities (0.45, 3, 5, 7, and 9 mT). The normal magnetic field of the laboratory was assayed as 0.45 mT (control). Optimization of magnetic field intensity and exposure time significantly increased biomass production and invertase activity compared to 0.45 mT. The maximum invertase activity (51.14 U/mL) and biomass concentration (4.36 g/L) were achieved with the spores obtained at the 144 hr exposure time and 5 mT magnetic field intensity. The effect of low-intensity static magnetic fields (SMFs) on invertase activities of molds was investigated for the first time in the present study. As an additional contribution, a new hyper-invertase-producing mold strain was isolated.

  12. Assessing a Pesticide Exposure Intensity Algorithm in the Agricultural Health Study

    PubMed Central

    Thomas, Kent W.; Dosemeci, Mustafa; Coble, Joseph B.; Hoppin, Jane A.; Sheldon, Linda S.; Chapa, Guadalupe; Croghan, Carry W.; Jones, Paul A.; Knott, Charles E.; Lynch, Charles F.; Sandler, Dale P.; Blair, Aaron E.; Alavanja, Michael C.

    2010-01-01

    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 (AHS) is a prospective cohort study of pesticide applicators who provided detailed questionnaire information on their use of specific pesticides. A field study was performed for a subset of the applicators enrolled in the AHS to assess a pesticide exposure algorithm through comparison of algorithm intensity scores with measured exposures. Pre- and post-application urinary biomarker measurements were made for 2,4-D (n = 69) and chlorpyrifos (n = 17) applicators. Dermal patch, hand wipe, and personal air samples were also collected. Intensity scores were calculated using information from technician observations and an interviewer-administered questionnaire. Correlations between observer and questionnaire intensity scores were high (Spearman r = 0.92 and 0.84 for 2,4-D and chlorpyrifos, respectively). Intensity scores from questionnaires for individual applications were significantly correlated with post-application urinary concentrations for both 2,4-D (r = 0.42, p < 0.001) and chlorpyrifos (r = 0.53, p = 0.035) applicators. Significant correlations were also found between intensity scores and estimated hand loading, estimated body loading, and air concentrations for 2,4-D applicators (r-values 0.28–0.50, p-values<0.025). Across all chlorpyrifos applicators, body loading measurements were significantly correlated with intensity scores from questionnaires (r=0.50, p=0.039) but not from observations (r=0.18, p=0.482). Dermal measures for in-furrow granular applications of chlorpyrifos (n = 12) were very low and not correlated with intensity scores. A linear regression model indicated that the algorithm factors for individual applications explained 24% of the variability in post

  13. Magnetic field exposure of commercial airline pilots.

    PubMed

    Hood; Nicholas; Butler; Lackland; Hoel; Mohr

    2000-10-01

    PURPOSE: Airline pilots are exposed to magnetic fields generated by the aircraft's electrical and electronic systems. The purpose of this study was to directly measure the flight deck magnetic fields to which commercial airline pilots are exposed when flying on different aircraft types over a 75-hour flight-duty month.METHODS: Magentic field measurements were taken using personal dosimeters capable of measuring magnetic fields in the 40-800 Hz frequency range. Dosimeters were carried by either the Captain or the First Officer on Boeing 737/200, Boeing 747/400, Boeing 767/300ER, and Airbus 320 aircraft. The data were analyzed by aircraft type, with statistics based on block hours. Block hours begin when the aircraft departs the gate prior to take off and end when the aircraft returns to the gate after landing.RESULTS: Approximately 1008 block hours were recorded at a sampling rate of 3 seconds. Total block time exposure to the pilots ranged from a harmonic geometric mean of 6.7 milliGauss (mG) for the Boeing 767/300ER to 12.7 mG for the Boeing 737/200.CONCLUSIONS: Measured flight deck magnetic field levels were substantially above the 0.8 to 1 mG level typically found in the home or office and suggest the need for further study to evaluate potential health effects of long-term exposure.

  14. An Updated Algorithm for Estimation of Pesticide Exposure Intensity in the Agricultural Health Study

    EPA Science Inventory

    An algorithm developed to estimate pesticide exposure intensity for use in epidemiologic analyses was revised based on data from two exposure monitoring studies. In the first study, we estimated relative exposure intensity based on the results of measurements taken during the app...

  15. An Updated Algorithm for Estimation of Pesticide Exposure Intensity in the Agricultural Health Study

    EPA Science Inventory

    An algorithm developed to estimate pesticide exposure intensity for use in epidemiologic analyses was revised based on data from two exposure monitoring studies. In the first study, we estimated relative exposure intensity based on the results of measurements taken during the app...

  16. The dependence of spike field coherence on expected intensity.

    PubMed

    Lepage, Kyle Q; Kramer, Mark A; Eden, Uri T

    2011-09-01

    The coherence between neural spike trains and local-field potential recordings, called spike-field coherence, is of key importance in many neuroscience studies. In this work, aside from questions of estimator performance, we demonstrate that theoretical spike-field coherence for a broad class of spiking models depends on the expected rate of spiking. This rate dependence confounds the phase locking of spike events to field-potential oscillations with overall neuron activity and is demonstrated analytically, for a large class of stochastic models, and in simulation. Finally, the relationship between the spike-field coherence and the intensity field coherence is detailed analytically. This latter quantity is independent of neuron firing rate and, under commonly found conditions, is proportional to the probability that a neuron spikes at a specific phase of field oscillation. Hence, intensity field coherence is a rate-independent measure and a candidate on which to base the appropriate statistical inference of spike field synchrony.

  17. Selective bond breaking of CO2 in phase-locked two-color intense laser fields: laser field intensity dependence.

    PubMed

    Endo, Tomoyuki; Fujise, Hikaru; Kawachi, Yuuna; Ishihara, Ayaka; Matsuda, Akitaka; Fushitani, Mizuho; Kono, Hirohiko; Hishikawa, Akiyoshi

    2017-02-01

    Selective bond breaking of CO2 in phase-locked ω-2ω two-color intense laser fields (λ = 800 nm and 400 nm, total field intensity I ∼ 10(14) W cm(-2)) has been investigated by coincidence momentum imaging. The CO(+) and O(+) fragment ions produced by two-body Coulomb explosion, CO2(2+) → CO(+) + O(+), exhibit asymmetric distributions along the laser polarization direction, showing that one of the two equivalent C-O bonds is selectively broken by the laser fields. At a field intensity higher than 2 × 10(14) W cm(-2), the largest fragment asymmetry is observed when the relative phase ϕ between the ω and 2ω laser fields is ∼0 and π. On the other hand, an increase of the asymmetry and a shift of the phase providing the largest asymmetry are observed at lower field intensities. The selective bond breaking and its dependence on the laser field intensity are discussed in terms of a mechanism involving deformation of the potential energy surfaces and electron recollision in intense laser fields.

  18. Fourth-order acoustic torque in intense sound fields

    NASA Technical Reports Server (NTRS)

    Wang, T. G.; Kanber, H.; Olli, E. E.

    1978-01-01

    The observation of a fourth-order acoustic torque in intense sound fields is reported. The torque was determined by measuring the acoustically induced angular deflection of a polished cylinder suspended by a torsion fiber. This torque was measured in a sound field of amplitude greater than that in which first-order acoustic torque has been observed.

  19. Fourth-order acoustic torque in intense sound fields

    NASA Technical Reports Server (NTRS)

    Wang, T. G.; Kanber, H.; Olli, E. E.

    1978-01-01

    The observation of a fourth-order acoustic torque in intense sound fields is reported. The torque was determined by measuring the acoustically induced angular deflection of a polished cylinder suspended by a torsion fiber. This torque was measured in a sound field of amplitude greater than that in which first-order acoustic torque has been observed.

  20. Globally strong geomagnetic field intensity circa 3000 years ago

    NASA Astrophysics Data System (ADS)

    Hong, Hoabin; Yu, Yongjae; Lee, Chan Hee; Kim, Ran Hee; Park, Jingyu; Doh, Seong-Jae; Kim, Wonnyon; Sung, Hyongmi

    2013-12-01

    High-fidelity geomagnetic field intensity determination was carried out using 191 baked fragments collected from 20 kilns or hearths with ages ranging between ∼1200 BC and ∼AD 1725 in South Korea. Geomagnetic field intensity variation displayed three narrow minima at ∼800-700 BC, ∼AD 700, and ∼AD 1600 and two maxima at ∼1200-1100 BC and ∼AD 1000-1100. In most time intervals, virtual axial dipole moment (VADM) variation is confined within 20% of the present VADM. However, geomagnetic field intensity circa 3000 yr ago is nearly 40% larger than the present value. Such high VADMs circa 3000 yr ago are in phase with those in other longitudinal bands in northern hemisphere centered at 5E (France), 30E (the Middle East) and 200E (Hawaii). Although strong geomagnetic field intensity circa 3000 yr ago is globally synchronous, the highest VADM occurs at slightly different time intervals in different locations. Hence it is possible that the globally strong geomagnetic field intensity circa 3000 yr ago reflects the migration of persistent hemispheric flux in northern hemisphere or an episode of geomagnetic field hemispheric asymmetry.

  1. Intermittent exposure to bright light in field conditions.

    PubMed

    Boivin, Diane B; James, Francine O

    2004-03-01

    The Interactive Neurobehavioral Model integrates Kronauer's and Jewett's latest mathematical model of the resetting effect of light on the human circadian pacemaker. This model is based on several lines of experimental evidence and considers the endogenous circadian pacemaker as a complex oscillatory system that responds dynamically to the resetting effect of light. This model can help us understand the results of an experiment using intermittent bright light exposure in the workplace environment. Intermittent exposure to bright light was effectively used as part of an intervention to promote circadian re-entrainment of a group of nurses to their permanent night work schedule. Regular exposure to lower light levels and darkness also provided a significant phase delay of endogenous circadian rhythms, although the adaptation was incomplete in this group of workers. These last results are consistent with the intensity-dependent component of the model. The development of better tools to measure retinal exposure to light throughout the 24-h day is required to adequately test modeling predictions under field conditions.

  2. Intense electron beam propagation across a magnetic field

    SciTech Connect

    Zhang, X.; Striffler, C.D.; Yao, R.L.; Destler, W.W.; Reiser, M.P.

    1989-01-01

    In this paper we consider the propagation of an intense electron-ion beam across an applied magnetic field. In the absence of the applied field, the beam system is in a Bennett equilibrium state that involves electrons with both large axial and thermal velocities and a cold stationary space-charge neutralizing ion species. Typical parameters under consideration are V{sub o} {approximately} 1 MV, I {approximately} 5 kA, T{sub e} {approximately} 100 keV, and beam radii {approximately} 1 cm. We find that in the intense beam regime, the propagation is limited due to space-charge depression caused by the deflection of the electron beam by the transverse field. This critical field is of the order of the peak self-magnetic field of the electron beam which is substantially higher than the single particle cut-off field. 8 refs., 3 figs.

  3. On intense diverging electric field associated with black aurora

    SciTech Connect

    Marklund, G.; Blomberg, L.; Faelthammar, C.G.; Lindqvist, P.A.

    1994-08-15

    The authors present measurements made from the double-probe electric field instrument on the Freja satellite of a very intense electric field event seen in the auroral oval. The electric field measurements are correlated with potential, charged particle, and wave activity measurements. They see two very narrow electric field events separated by approximately 5 km, having field strengths near 1 V/m. These structures are seen to be associated with an excess of positive charge, to be associated with no electron precipitation, with slight plasma depletions, and with wave activity. The authors suggest these structures are black aurorae, with a total absence of auroral emissions.

  4. Intense-field renormalization of cavity-induced spontaneous emission

    NASA Astrophysics Data System (ADS)

    Agarwal, G. S.; Lange, W.; Walther, H.

    1993-12-01

    We examine theoretically the recent experiments of Lange and Walther on the dynamical interaction of Rydberg atoms in a microwave cavity in the presence of a strong driving field. In particular, we study how the intense field renormalizes the cavity-induced spontaneous emission. For this purpose we derive the master equation for the atomic dynamics by adiabatically eliminating the cavity-field variables, while treating the intense driving field nonperturbatively. We present analytical and numerical solutions of the master equation, taking into account the turn on and turn off of the atom-field coupling in the rest frame of the atoms, as well as the velocity distribution of the atomic beam. We obtain good agreement between theoretical results and experiments.

  5. Biologic effects of prolonged exposure to ELF electromagnetic fields in rats. 2: 50 Hz magnetic fields

    SciTech Connect

    Margonato, V.; Cerretelli, P.; Nicolini, P.; Conti, R.; Zecca, L.; Veicsteinas, Z.

    1995-12-31

    To provide possible laboratory support to health risk evaluation associated with long-term, low-intensity magnetic field exposure, 256 male albino rats and an equal number of control animals (initial age 12 weeks) were exposed 22 h/day to a 50 Hz magnetic flux density of 5 {micro}T for 32 weeks (a total of about 5,000 h). Hematology was studied from blood samples before exposure to the field and at 12 week intervals. Morphology and histology of liver, heart, mesenteric lymph nodes, and testes as well as brain neurotransmitters were assessed at the end of the exposure period. In two identical sets of experiments, no significant differences in the investigated variables were found between exposed and sham-exposed animals. It is concluded that continuous exposure to a 50 Hz magnetic field of 5 {micro}T from week 12 to week 44, which makes up {approximately}70% of the life span of the rat before sacrifice, does not cause changes in growth rate, in the morphology and histology of liver, heart, mesenteric lymph nodes, testes, and bone marrow, in hematology and hematochemistry, or in the neurotransmitters dopamine and serotonin.

  6. Anomalous Radiative Trapping in Laser Fields of Extreme Intensity

    NASA Astrophysics Data System (ADS)

    Gonoskov, A.; Bashinov, A.; Gonoskov, I.; Harvey, C.; Ilderton, A.; Kim, A.; Marklund, M.; Mourou, G.; Sergeev, A.

    2014-07-01

    We demonstrate that charged particles in a sufficiently intense standing wave are compressed toward, and oscillate synchronously at, the antinodes of the electric field. We call this unusual behavior anomalous radiative trapping (ART). We show using dipole pulses, which offer a path to increased laser intensity, that ART opens up new possibilities for the generation of radiation and particle beams, both of which are high energy, directed, and collimated. ART also provides a mechanism for particle control in high-intensity quantum-electrodynamics experiments.

  7. Synchrotron Intensity Gradients as Tracers of Interstellar Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Lazarian, A.; Yuen, Ka Ho; Lee, Hyeseung; Cho, J.

    2017-06-01

    On the basis of the modern understanding of MHD turbulence, we propose a new way of using synchrotron radiation: using synchrotron intensity gradients (SIGs) for tracing astrophysical magnetic fields. We successfully test the new technique using synthetic data obtained with 3D MHD simulations and provide the demonstration of the practical utility of the technique by comparing the directions of magnetic fields that are obtained with PLANCK synchrotron intensity data to the directions obtained with PLANCK synchrotron polarization data. We demonstrate that the SIGs can reliably trace magnetic fields in the presence of noise and can provide detailed maps of magnetic field directions. We also show that the SIGs are relatively robust for tracing magnetic fields while the low spatial frequencies of the synchrotron image are removed. This makes the SIGs applicable to the tracing of magnetic fields using interferometric data with single-dish measurement absent. We discuss the synergy of using the SIGs together with synchrotron polarization in order to find the actual direction of the magnetic fields and quantify the effects of Faraday rotation as well as with other ways of studying astrophysical magnetic fields. We test our method in the presence of noise and the resolution effects. We stress the complementary nature of the studies using the SIG technique and those employing the recently introduced velocity gradient techniques that trace magnetic fields using spectroscopic data.

  8. On Acceptable Exposures to Short Pulses of Electromagnetic Fields

    DTIC Science & Technology

    2015-09-01

    NAWCWD TP 8791 On Acceptable Exposures to Short Pulses of Electromagnetic Fields by Francis X. Canning, PhD Physics...prepared in response to a request to study the effects of exposure to short pulses of electromagnetic fields. The author is a physicist at the Naval... Exposures to Short Pulses of Electromagnetic Fields (U) 5a. CONTRACT NUMBER N/A 5b. GRANT NUMBER N/A 5c. PROGRAM ELEMENT NUMBER N/A 6. AUTHOR(S

  9. Heating of cardiovascular stents in intense radiofrequency magnetic fields.

    PubMed

    Foster, K R; Goldberg, R; Bonsignore, C

    1999-01-01

    We consider the heating of a metal stent in an alternating magnetic field from an induction heating furnace. An approximate theoretical analysis is conducted to estimate the magnetic field strength needed to produce substantial temperature increases. Experiments of stent heating in industrial furnaces are reported, which confirm the model. The results show that magnetic fields inside inductance furnaces are capable of significantly heating stents. However, the fields fall off very quickly with distance and in most locations outside the heating coil, field levels are far too small to produce significant heating. The ANSI/IEEE C95.1-1992 limits for human exposure to alternating magnetic fields provide adequate protection against potential excessive heating of the stents.

  10. [ASSESSMENT OF OCCUPATIONAL EXPOSURE TO RADIO FREQUENCY ELECTROMAGNETIC FIELDS].

    PubMed

    Aniołczyk, Halina; Mariańska, Magda; Mamrot, Paweł

    2015-01-01

    European Union Directive 2013/35/UE provides for the implementation of EU regulations into national legislation. Our aim is to assess actual health hazards from radiofrequency eldctromagnetic field (RF EMF) (range: 100 kHz - 300 GHz) and indicate workplaces with the highest risk to employee health. Data from measurements of RF EMF performed by the Laboratory of Electromagnetic Hazards in Nofer Institute of Occupational Medicine (Łódź, Poland) were analyzed. The analysis covered the results of electric field intensity (E) for over 450 selected items. The ranges of protection zones and the extent to which maximum admissible intensity (MAI) values were also analyzed. The determinations and'measurements of EMF in the work environment met the requirements of Polish Standard, while Polish regulations on the MAI values were used as the criterion for the assessment of the exposure. The highest values of E field intensity at workplaces were measured for: electrosurgery, to 400 V/m, and short-wave diathermy units, to 220 V/m, dielectric welders to 240 V/m, within the FM radio antenna systems, to 180 V/m. The widest protection zones were noted for prototype research instruments, short-wave diathermy units, and dielectric welders. The most excessive (up to 12-fold MAI) values were recorded for dielectric welders, short-wave diathermy units (up to 11-fold) and microwave diathermy units (up to 8-fold). Our results have confirmed the high RF EMF values for physiotherapists, operators of dielectric welders, and mast maintenance workers in radio com munication facilities (especially radio and TV broadcasting stations).

  11. Light alters nociceptive effects of magnetic field shielding in mice: intensity and wavelength considerations

    PubMed Central

    Prato, Frank S; Desjardins-Holmes, Dawn; Keenliside, Lynn D; McKay, Julia C; Robertson, John A; Thomas, Alex W

    2008-01-01

    Previous experiments with mice have shown that repeated 1 hour daily exposure to an ambient magnetic field-shielded environment induces analgesia (antinociception). The exposures were carried out in the dark (less than 2.0×1016 photons s−1 m−2) during the mid-light phase of the diurnal cycle. However, if the mice were exposed in the presence of visible light (2.0×1018 photons s−1 m−2, 400–750 nm), then the analgesic effects of shielding were eliminated. Here, we show that this effect of light is intensity and wavelength dependent. Introduction of red light (peak at 635 nm) had little or no effect, presumably because mice do not have photoreceptors sensitive to red light above 600 nm in their eyes. By contrast, introduction of ultraviolet light (peak at 405 nm) abolished the effect, presumably because mice do have ultraviolet A receptors. Blue light exposures (peak at 465 nm) of different intensities demonstrate that the effect has an intensity threshold of approximately 12% of the blue light in the housing facility, corresponding to 5×1016 photons s−1 m−2 (integral). This intensity is similar to that associated with photoreceptor-based magnetoreception in birds and in mice stimulates photopic/cone vision. Could the detection mechanism that senses ambient magnetic fields in mice be similar to that in bird navigation? PMID:18583276

  12. Response of aquatic protists to electric field exposure.

    PubMed

    Miliša, Marko; Đikić, Domagoj; Mandić, Tvrtko; Grozić, Dino; Čolić, Ivan; Ostojić, Ana

    2017-08-01

    To test the effects of short-term exposure of aquatic organisms to electric field (EF) with negligible magnetic component. We built a plate capacitor that served as a source of EF of strengths that can be found in nature near transmission lines. We exposed two cultured protist species Euglena viridis and Paramecium caudatum to EFs for 24 hours and monitored their abundance, morphology, intracellular superoxide anion (by dihydroethidium [DHE]), hydrogen peroxide by (H2DCF) and lipid peroxidation (MDA) contents, catalase (CAT) and superoxide dismutase (SOD) activity. We found that even short-term exposure to low strength EF causes changes in population abundance, morphology and oxidative stress response in both species. As the EF strength increased, abundance of both species decreased. However, at weaker EFs, fission rates were seemingly promoted. We noted a decrease in size in both organisms in directions perpendicular to their fission planes correlated with EF strength. DHE and H2DCF fluorescence intensity and SOD activity were higher in organisms exposed to the stronger EFs. We suggest that the electric component of the field, rather than the magnetic, is the main cause of all the noted effects. As a result, aquatic organisms should be given greater importance in studies assessing the effects of EMFs in spite of the attenuating effects of water to EF strengths.

  13. Acute high-intensity sound exposure alters responses of place cells in hippocampus.

    PubMed

    Goble, T J; Møller, A R; Thompson, L T

    2009-07-01

    Overstimulation is known to activate neural plasticity in the auditory nervous system causing changes in function and re-organization. It has been shown earlier that overstimulation using high-intensity noise or tones can induce signs of tinnitus. Here we show in studies in rats that overstimulation causes changes in the way place cells of the hippocampus respond as rats search for rewards in a spatial maze. In familiar environments, a subset of hippocampal pyramidal neurons, known as place cells, respond when the animal moves through specific locations but are relatively silent in others. This place-field activity (i.e. location-specific firing) is stable in a fixed environment. The present study shows that activation of neural plasticity through overstimulation by sound can alter the response of these place cells. Rats implanted with chronic drivable dorsal hippocampal tetrodes (four microelectrodes) were assessed for stable single-unit place-field responses that were extracted from multiunit responses using NeuroExplorer computer spike-sorting software. Rats then underwent either 30 min exposure to a 4 kHz tone at 104 dB SPL or a control period in the same sound chamber. The place-field activity was significantly altered after sound exposure showing that plastic changes induced by overstimulation are not limited to the auditory nervous system but extend to other parts of the CNS, in this case to the hippocampus, a brain region often studied in the context of plasticity.

  14. Far-field intensity of Lorentz related beams

    NASA Astrophysics Data System (ADS)

    Peng, Xi; Chen, Chidao; Chen, Bo; Peng, Yulian; Zhou, Meiling; Zhang, Liping; Li, Dongdong; Deng, Dongmei

    2016-12-01

    We introduce a sufficient condition under which the Lorentz beam convolution with other beams constitutes valid cross-spectral densities. Two examples are given to show how the Lorentz related beam can be used for generation of a far field being a modulated version of another one. The far-field intensity patterns in the Cartesian symmetries by the convolution operation of the Lorentz beams with multi-sinc beams, and the convolution operation of the Lorentz beams with multi-sinc Gaussian beams, are shown respectively. We find that different beam order can result distinct far field changes.

  15. Zeeman degeneracy effects in collisional intense-field resonance fluorescence

    NASA Technical Reports Server (NTRS)

    Cooper, J.; Ballagh, R. J.; Burnett, K.

    1980-01-01

    Resonance fluorescence due to intense laser fields from a Zeeman degenerate atom being perturbed by collisional interactions is calculated in the impact regime by using the quantum-fluctuation-regression theorem. Various interesting effects are found. For example, the scattered intensity spectrum for a J = 0 to J = 1 transition for polarization parallel to the laser polarization is essentially an asymmetric triplet, whereas for a perpendicular polarization due to collisions the spectrum is essentially a doublet (whose frequencies do not correspond with any of those of the triplet). Further, the width of the fluorescent component (whose frequency is close to the unperturbed frequency) actually decreases with increasing laser power.

  16. Skin temperature changes induced by strong static magnetic field exposure.

    PubMed

    Ichioka, Shigeru; Minegishi, Masayuki; Iwasaka, Masakazu; Shibata, Masahiro; Nakatsuka, Takashi; Ando, Joji; Ueno, Shoogo

    2003-09-01

    High intensity static magnetic fields, when applied to the whole body of the anesthetized rat, have previously been reported to decrease skin temperature. The hypothesis of the present study was that in diamagnetic water, molecules in the air play significant roles in the mechanism of skin temperature decrease. We used a horizontal cylindrical superconducting magnet. The magnet produced 8 T at its center. A thermistor probe was inserted in a subcutaneous pocket of the anesthetized rats to measure skin temperature. Animals (n=10) were placed in an open plastic holder in which the ambient air was free to move in any direction (group I). Animals (n=10) were placed in a closed holder in which the air circulation toward the direction of weak magnetic field was restricted (group II). Each holder was connected to a hydrometer to measure humidity around the animal in the holder. The data acquisition phase consisted of a 5 min baseline interval, followed by inserting the animal together with the holder into the center of the magnet bore for a 5 min exposure and a 5 min postexposure period outside the bore. In group I, skin temperature and humidity around the animal significantly decreased during exposure, followed by recovery after exposure. In group II, skin temperature and humidity did not decrease during the measurement. The skin temperature decrease was closely related to the decrease in humidity around the body of the animal in the holder, and the changes were completely blocked by restricting the air circulation in the direction of the bore entrance. Possible mechanisms responsible for the decrease in skin temperature may be associated with magnetically induced movement of water vapor at the skin surface, leading to skin temperature decrease. Copyright 2003 Wiley-Liss, Inc.

  17. Decrease of luminol chemiluminescence upon exposure of human blood serum to 50 Hz electric fields.

    PubMed

    Calota, Violeta; Dragoiu, Simona; Meghea, Aurelia; Giurginca, Maria

    2006-09-01

    The chemiluminescence of luminol, after 1 and 2h in vitro exposure of human serum to 50 Hz electric fields of different intensities, decreases as compared to the controls. This indicates a field-induced decrease in the concentration of the free radicals. The report is limited to the key kinetic and field data, inviting independent kinetic analysis of the data in terms of reaction moments or reaction susceptibilities for the various normal modes indicated by the data.

  18. Task-based estimation of past exposures to 60-hertz magnetic and electric fields at an electrical utility.

    PubMed

    Deadman, J E; Church, G; Bradley, C; Armstrong, B G; Thériault, G

    1997-12-01

    Past exposures of electric utility workers to extremely low-frequency (ELF) magnetic (B) and electric fields (E) in Quebec were estimated. The current intensities were measured and durations of exposures determined for tasks or work locations in 14 job categories. Past task or location intensities were extrapolated from the present on the basis of interviews with long-term workers and utility personnel. Past task or location durations were estimated for the long-term workers. Time-weighted average (TWA) exposures for past periods were reconstructed for jobs from the intensity and duration estimates. Magnetic fields were estimated to have increased the most over time for substation and distribution-line jobs. Magnetic field exposures for jobs in the generation and transmission of electricity were estimated to have increased very little. For substation jobs, the ratios of magnetic fields in 1945 to those in 1990 ranged from 0.42 to 0.69; the corresponding figures for distribution-line jobs ranged from 0.36 to 0.94. For electric fields in substations, the estimated increase over time was less than for magnetic fields, the 1945:1990 ratios ranging from 0.59 to 0.88. For the distribution line jobs, the 1945:1990 ratios for electric fields were less than 1.0 in 4 cases (0.6 to 0.89), more than 1.0 in 3 others (1.13 to 2.01) and unchanged in 1. Reconstruction of TWA exposures allowed changes in the intensity and the duration of exposures to be considered separately. Documentation of the intensity and duration of exposures for different tasks allows exposure reconstruction for jobs that have ceased to exist. The method is applicable elsewhere if exposure-monitoring records allow the level and duration of exposures for tasks or locations to be calculated and if estimates of past durations and intensities of exposures can be reliably obtained.

  19. Estimating storm areal average rainfall intensity in field experiments

    NASA Astrophysics Data System (ADS)

    Peters-Lidard, Christa D.; Wood, Eric F.

    1994-07-01

    Estimates of areal mean precipitation intensity derived from rain gages are commonly used to assess the performance of rainfall radars and satellite rainfall retrieval algorithms. Areal mean precipitation time series collected during short-duration climate field studies are also used as inputs to water and energy balance models which simulate land-atmosphere interactions during the experiments. In two recent field experiments (1987 First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE) and the Multisensor Airborne Campaign for Hydrology 1990 (MAC-HYDRO '90)) designed to investigate the climatic signatures of land-surface forcings and to test airborne sensors, rain gages were placed over the watersheds of interest. These gages provide the sole means for estimating storm precipitation over these areas, and the gage densities present during these experiments indicate that there is a large uncertainty in estimating areal mean precipitation intensity for single storm events. Using a theoretical model of time- and area-averaged space- time rainfall and a model rainfall generator, the error structure of areal mean precipitation intensity is studied for storms statistically similar to those observed in the FIFE and MAC-HYDRO field experiments. Comparisons of the error versus gage density trade-off curves to those calculated using the storm observations show that the rainfall simulator can provide good estimates of the expected measurement error given only the expected intensity, coefficient of variation, and rain cell diameter or correlation length scale, and that these errors can quickly become very large (in excess of 20%) for certain storms measured with a network whose size is below a "critical" gage density. Because the mean storm rainfall error is particularly sensitive to the correlation length, it is important that future field experiments include radar and/or dense rain gage networks capable of accurately characterizing the

  20. Electric and magnetic field exposure, chemical exposure, and leukemia risk in electrical'' occupations

    SciTech Connect

    Bowman, J.D.; Sobel, E.; London, S.J.; Thomas, D.C.; Garabrant, D.H.; Pearce, N.; Peters, J.M. . Dept. of Preventive Medicine)

    1992-12-01

    This project was conducted to address what are the extremely low frequency (ELF) magnetic and electric field exposures of workers in electrical'' occupations and do they exceed exposures encountered in non-electrical'' occupations and what are the chemical and physical exposures in the electrical'' occupations and do they exceed exposures encountered in non-electrical'' occupations Two subsidiary issues were does characterization and quantification of ELF magnetic field exposure in the electrical'' occupations provide data to support a dose response relationship between leukemia risk and electric or magnetic field exposure and do dffferences in chemical exposure between the occupations help explain the previously observed leukemia risk associated with these electrical'' occupations Data were collected in 3 regions in which electrical workers had been reported to have an excess of leukemia - New Zealand, Los Angeles and Seattle Measurements of magnetic fields were made on 493 electrical workers and 163 non-electrical workers.

  1. Electric and magnetic field exposure, chemical exposure, and leukemia risk in ``electrical`` occupations. Final report

    SciTech Connect

    Bowman, J.D.; Sobel, E.; London, S.J.; Thomas, D.C.; Garabrant, D.H.; Pearce, N.; Peters, J.M.

    1992-12-01

    This project was conducted to address what are the extremely low frequency (ELF) magnetic and electric field exposures of workers in ``electrical`` occupations and do they exceed exposures encountered in ``non-electrical`` occupations? and what are the chemical and physical exposures in the ``electrical`` occupations and do they exceed exposures encountered in ``non-electrical`` occupations? Two subsidiary issues were does characterization and quantification of ELF magnetic field exposure in the ``electrical`` occupations provide data to support a dose response relationship between leukemia risk and electric or magnetic field exposure? and do dffferences in chemical exposure between the occupations help explain the previously observed leukemia risk associated with these ``electrical`` occupations? Data were collected in 3 regions in which electrical workers had been reported to have an excess of leukemia - New Zealand, Los Angeles and Seattle Measurements of magnetic fields were made on 493 electrical workers and 163 non-electrical workers.

  2. Investigation of uniformity field generated from freeform lens with UV LED exposure system

    NASA Astrophysics Data System (ADS)

    Ciou, F. Y.; Chen, Y. C.; Pan, C. T.; Lin, P. H.; Lin, P. H.; Hsu, F. T.

    2015-03-01

    In the exposure process, the intensity and uniformity of light in the exposure area directly influenced the precision of products. UV-LED (Ultraviolet Light-Emitting Diode) exposure system was established to reduce the radiation leakage and increase the energy efficiency for energy saving. It is a trend that conventional mercury lamp could be replaced with UV-LED exposure system. This study was based on the law of conservation of energy and law of refraction of optical field distributing on the target plane. With these, a freeform lens with uniform light field of main exposure area could be designed. The light outside the exposure area could be concentrated into the area to improve the intensity of light. The refraction index and UV transmittance of Polydimethylsiloxane (PDMS) is 1.43 at 385 nm wavelength and 85-90%, respectively. The PDMS was used to fabricate the optics lens for UV-LEDs. The average illumination and the uniformity could be obtained by increasing the number of UV-LEDs and the spacing of different arrangement modes. After exposure process with PDMS lens, about 5% inaccuracy was obtained. Comparing to 10% inaccuracy of general exposure system, it shows that it is available to replace conventional exposure lamp with using UV-LEDs.

  3. Electron emission and fragmentation of molecules in intense laser fields

    NASA Astrophysics Data System (ADS)

    Ueda, K.; Prümper, G.; Hatamoto, T.; Okunishi, M.; Mathur, D.

    2007-06-01

    We have constructed an apparatus for high-resolution electron spectroscopy and electron-ion coincidence experiments on gas-phase molecules in intense laser fields. The apparatus comprises an electron time-of-flight (TOF) spectrometer and an ion TOF spectrometer with a position detector, placed on either side of an effusive molecular beam. The ionizing radiation is either the fundamental (800 nm wavelength) of a Ti:sapphire laser or frequency doubled 400-nm light, with pulse durations of ~ 150 fs and the repetition rate of 1 kHz. We have investigated the electron emission and fragmentation of linear alcohol molecules, methanol, ethanol and 1-propanol, in laser fields with peak intensities up to ~ 1×10 14 W/cm2. Details of our apparatus are described along with an overview of some recent results.

  4. Intense ionospheric electric and magnetic field pulses generated by lightning

    NASA Technical Reports Server (NTRS)

    Kelley, M. C.; Ding, J. G.; Holzworth, R. H.

    1990-01-01

    Electric and magnetic field measurements have been made in the ionosphere over an active thunderstorm and an optical detector onboard the same rocket yielded an excellent time base for the study of waves radiated into space from the discharge. In addition to detection of intense, but generally well understood whistler mode waves, very unusual electric and magnetic field pulses preceded the 1-10 kHz component of the radiated signal. These pulses lasted several ms and had a significant electric field component parallel to the magnetic field. No known propagating wave mode has this polarization nor a signal propagation velocity as high as those measured here. This study investigated and rejected an explanation based on an anomalous skin depth effect. Although only a hypothesis at this time, a more promising explanation involving the generation of the pulse via a nonlinear decay of whistler mode waves in the frequency range 10-80 kHz is being investigated.

  5. How do protozoa respond to intense magnetic fields?

    NASA Astrophysics Data System (ADS)

    Guevorkian, Karine

    2005-03-01

    Most microorganisms such as Paramecium Caudatum, swim in helical paths in nature. In the absence of any external stimuli (e.g. obstacles, electric field, heat, etc.) the axes of these helical paths, which define the trajectories, are straight lines and are distributed in random directions. Our experiments reveal that these trajectories can be manipulated by applying intense DC magnetic fields of the order of several Tesla. Swimming paramecia, for example, align their trajectories with magnetic fields in excess of about 7 Tesla in fraction of a second. We will describe this phenomenon in fields up to 25 T. We will address whether this effect is an active or passive response to the magnetic torque exerted on the diamagnetically anisotropic structures in Paramecium. In addition we will present results for other species as they are obtained.

  6. Intensity calibration and flat-field correction for fluorescence microscopes.

    PubMed

    Model, Michael

    2014-04-01

    Standardization in fluorescence microscopy involves calibration of intensity in reproducible units and correction for spatial nonuniformity of illumination (flat-field or shading correction). Both goals can be achieved using concentrated solutions of fluorescent dyes. When a drop of a highly concentrated fluorescent dye is placed between a slide and a coverslip it produces a spatially uniform field, resistant to photobleaching and with reproducible quantum yield; it can be used as a brightness standard for wide-field and confocal microscopes. For wide-field microscopes, calibration can be further extended to absolute molecular units. This can be done by imaging a solution of known concentration and known depth; the latter can be prepared by placing a small spherical lens in a diluted solution of the same fluorophore that is used in the biological specimen.

  7. Atoms, molecules and clusters in intense laser fields

    NASA Astrophysics Data System (ADS)

    Walters, Zachary B.

    Recent advances in the technology of intense, short laser pulses have opened the possibility of investigating processes in atoms, molecules and clusters in which the normal intramolecular forces between electrons and nuclei, and between different electrons, are rivaled in strength by interactions with the driving laser, or with a cluster plasma. Experiments using rescattered electrons offer a means of probing atomic and molecular processes on ultrafast timescales. This thesis extends techniques and concepts of atomic and molecular physics to describe physics in the strong field regime. This involves investigating how electron scattering from atoms and molecules is affected by the intense and time-varying electric field of the laser, the effect of such scattering on experimental observables, and the role of intramolecular structure on strong field processes. Also investigated is the evolution of van derWaals atomic clusters when subject to intense laser pulses in the VUV regime. Here processes such as photoionization, inverse bremsstrahlung heating, and collisional ionization and recombination are affected both by the non-hydrogenic nature of the relevant atomic potentials but also by the screening of these potentials by the cluster plasma.

  8. Validation of a job-exposure matrix for assessment of utility worker exposure to magnetic fields.

    PubMed

    Johansen, Christoffer; Raaschou-Nielsen, Ole; Skotte, Jørgen; Thomsen, Birthe L; Olsen, Jørgen H

    2002-04-01

    The aim of this study was to evaluate a 50-Hz electromagnetic field job-exposure matrix used in epidemiological studies of a nationwide cohort of utility workers in Denmark. We compared a job-exposure matrix that distinguished four categories of exposure to 50-Hz time-weighted average (TWA) magnetic fields: low (< 0.1 microT), medium (0.1-0.29 microT), high (0.3-0.99 microT) and very high (> 1.0 microT) of utility company employees with 196 measurements of 8-h exposure for 129 workers in this industry. The 129 workers were selected from the following five main work environments: generation facilities, transmission lines, distribution lines, substations, and other electrically and non-electrically relates jobs. This study shows that the job-exposure matrix can be expected to introduce misclassification mainly between adjacent categories of exposure. Thus, the distribution of measurements of exposure to 50-Hz magnetic fields was similar for workers in the medium and the high exposure matrix categories. But the two extreme categories satisfactorily separate low and very highly exposed workers. The study shows that epidemiological use of this job-exposure matrix might combine the two intermediate categories of exposure. If the sample size in extreme categories provides enough power, a study in which this job-exposure matrix is used should allow detection of a true association between exposure to 50-Hz magnetic field and disease.

  9. Effects of high-intensity microwave pulse exposure of rat brain

    NASA Astrophysics Data System (ADS)

    Guy, Arthur W.; Chou, Chung-Kwang

    1982-01-01

    Previous studies have indicated that auditory responses could be evoked in the head of animals exposed to 500-μs-wide or less microwave pulses of relatively small absorbed energies (5-180 mJ/kg). These studies were extended using an exposure system capable of locally exposing the head and especially the brain of the animal to a single 915-MHz pulsed magnetic field with sufficient intensity to produce a specific absorption rate level as high as 4×105 W/kg for any pulse width. When the animal was exposed to various pulse widths (1μs to 360 ms) and power levels (2-10 kW), the animal displayed no reaction other than that due to the hearing effect until the peak absorbed energy density in the brain exceeded 28 kJ/kg, or an absorbed energy in the head of 680 J, regardless of peak power or pulse width. Thermographic and thermocouple measurements indicated a maximum temperature rise of 8°C or final maximum brain temperature of 46° -46.5°C at the reaction level. The reaction consisted of petit or grand mal seizures lasting for 1 min after exposure, followed by a 4- to 5-min unconscious state during which normal reflexes were displayed. There was a decrease in heartbeat rate in the exposed unanesthetized animals. After the period of unconsciousness the rats recovered without apparent effect from the exposure. Measurements indicated that the brain temperature returned to baseline level within 5 min after exposure and the animals began moving when the brain temperature returned to within 1°C of their normal values. These results would indicate that the thresholds for convulsions induced by short exposures of the brain to high energy pulses are dependent only on the deposited energy and temperature rise. Histological examinations of some of the animal brains indicated some demyelination of neurons 1 day after exposure and some microfocal glial nodules in the brain 1 month after exposure.

  10. Comparison of electric field exposure monitoring instrumentation. Final report

    SciTech Connect

    Bracken, T.D.

    1985-06-01

    Electric field exposure monitoring instrumentation was compared and evaluated during three days of tests performed in 60-Hz electric fields. A conducting vest exposure meter and a small electric field exposure meter (EFEM) located in a shirt pocket, arm band or hard hat were compared in a series of static and dynamic tests. In some tests, the devices were worn simultaneously without interference to provide separate measures of identical exposure. Tests with stationary subjects wearing the instruments were used to measure the effects of grounding, and to establish the meter response in a standard posture for each subject. Dynamic occupational exposure simulations were used to compare accumulated measurements of exposure between instruments and to compare measurements with predicted exposures. The simulations were based on analysis of the work-related behavior of substation electricians and operators. Electrician's tasks at ground level and in a bucket truck were simulated near an energized test line. A simulated substation inspection was performed in a 230 kV substation. The exposure measurements demonstrated an overall consistency between the meters. The vest demonstrated less intersubject variability and less detailed exposure characterization. Measurements with the shirt pocket EFEM were below those made with the vest and with the EFEM in other locations. Insulation provided by shoe soles appeared to be the largest factor in reducing measured exposures during the substation inspection below those predicted from the unperturbed field. Improvements in meter design and additional measurements are suggested. 11 refs., 20 figs., 28 tabs.

  11. [Investigation of occupational exposure to power frequency electromagnetic fields in workers of power grid].

    PubMed

    Chen, Qing-song; Yang, Xiao-ying; Li, Run-qin; Zhu, Bao-yu; Zhang, Xiao; Gao, Yang; Huang, Han-lin; Li, Tao

    2012-08-01

    To measure and assess the levels of occupational exposure to power frequency electromagnetic fields in workers of power grid. PMM8053 electromagnetic fields measuring system with EHP-50 probe was used to measure the levels of electromagnetic fields at working place. Personal dosimeters (EMDEX LITE) were utilized to measure the individual exposure levels of power frequency magnetic field. The results were evaluated with the limitation criteria of GBZ2.2 and ICNIRP. In the 500 kV ultra high voltage substation, the intensity at 90% measure points of power electric field was more than 5 kV/m. The magnetic field intensity in the areas nearby reactors and capacitors was often higher than 100 µT, even several hundreds µT. The mean daily exposure levels of workers in power grid were between 0.04 and 5.0 µT, and the exposure levels of 70% workers were higher than 0.4 µT. In the areas of ultra high voltage and nearby the reactors and capacitors are the key control points for occupational health in power grid. There is acute health risk of workers exposed to high accumulative exposure levels.

  12. Identification of patterns in diffraction intensities affected by radiation exposure

    PubMed Central

    Borek, Dominika; Dauter, Zbigniew; Otwinowski, Zbyszek

    2013-01-01

    In an X-ray diffraction experiment, the structure of molecules and the crystal lattice changes owing to chemical reactions and physical processes induced by the absorption of X-ray photons. These structural changes alter structure factors, affecting the scaling and merging of data collected at different absorbed doses. Many crystallographic procedures rely on the analysis of consistency between symmetry-equivalent reflections, so failure to account for the drift of their intensities hinders the structure solution and the interpretation of structural results. The building of a conceptual model of radiation-induced changes in macromolecular crystals is the first step in the process of correcting for radiation-induced inconsistencies in diffraction data. Here the complexity of radiation-induced changes in real and reciprocal space is analysed using matrix singular value decomposition applied to multiple complete datasets obtained from single crystals. The model consists of a resolution-dependent decay correction and a uniform-per-unique-reflection term modelling specific radiation-induced changes. This model is typically sufficient to explain radiation-induced effects observed in diffraction intensities. This analysis will guide the parameterization of the model, enabling its use in subsequent crystallographic calculations. PMID:23254654

  13. Identification of patterns in diffraction intensities affected by radiation exposure.

    PubMed

    Borek, Dominika; Dauter, Zbigniew; Otwinowski, Zbyszek

    2013-01-01

    In an X-ray diffraction experiment, the structure of molecules and the crystal lattice changes owing to chemical reactions and physical processes induced by the absorption of X-ray photons. These structural changes alter structure factors, affecting the scaling and merging of data collected at different absorbed doses. Many crystallographic procedures rely on the analysis of consistency between symmetry-equivalent reflections, so failure to account for the drift of their intensities hinders the structure solution and the interpretation of structural results. The building of a conceptual model of radiation-induced changes in macromolecular crystals is the first step in the process of correcting for radiation-induced inconsistencies in diffraction data. Here the complexity of radiation-induced changes in real and reciprocal space is analysed using matrix singular value decomposition applied to multiple complete datasets obtained from single crystals. The model consists of a resolution-dependent decay correction and a uniform-per-unique-reflection term modelling specific radiation-induced changes. This model is typically sufficient to explain radiation-induced effects observed in diffraction intensities. This analysis will guide the parameterization of the model, enabling its use in subsequent crystallographic calculations.

  14. Gene and Protein Expression following Exposure to Radiofrequency Fields from Mobile Phones

    PubMed Central

    Vanderstraeten, Jacques; Verschaeve, Luc

    2008-01-01

    Background Since 1999, several articles have been published on genome-wide and/or proteome-wide response after exposure to radiofrequency (RF) fields whose signal and intensities were similar to or typical of those of currently used mobile telephones. These studies were performed using powerful high-throughput screening techniques (HTSTs) of transcriptomics and/or proteomics, which allow for the simultaneous screening of the expression of thousands of genes or proteins. Objectives We reviewed these HTST-based studies and compared the results with currently accepted concepts about the effects of RF fields on gene expression. In this article we also discuss these last in light of the recent concept of microwave-assisted chemistry. Discussion To date, the results of HTST-based studies of transcriptomics and/or proteomics after exposure to RF fields relevant to human exposure are still inconclusive, as most of the positive reports are flawed by methodologic imperfections or shortcomings. In addition, when positive findings were reported, no precise response pattern could be identified in a reproducible way. In particular, results from HTST studies tend to exclude the role of a cell stressor for exposure to RF fields at nonthermal intensities. However, on the basis of lessons from microwave-assisted chemistry, we can assume that RF fields might affect heat-sensitive gene or protein expression to an extent larger than would be predicted from temperature change only. But in all likelihood, this would concern intensities higher than those relevant to usual human exposure. Conclusions The precise role of transcriptomics and proteomics in the screening of bioeffects from exposure to RF fields from mobile phones is still uncertain in view of the lack of positively identified phenotypic change and the lack of theoretical, as well as experimental, arguments for specific gene and/or protein response patterns after this kind of exposure. PMID:18795152

  15. Gene and protein expression following exposure to radiofrequency fields from mobile phones.

    PubMed

    Vanderstraeten, Jacques; Verschaeve, Luc

    2008-09-01

    Since 1999, several articles have been published on genome-wide and/or proteome-wide response after exposure to radiofrequency (RF) fields whose signal and intensities were similar to or typical of those of currently used mobile telephones. These studies were performed using powerful high-throughput screening techniques (HTSTs) of transcriptomics and/or proteomics, which allow for the simultaneous screening of the expression of thousands of genes or proteins. We reviewed these HTST-based studies and compared the results with currently accepted concepts about the effects of RF fields on gene expression. In this article we also discuss these last in light of the recent concept of microwave-assisted chemistry. To date, the results of HTST-based studies of transcriptomics and/or proteomics after exposure to RF fields relevant to human exposure are still inconclusive, as most of the positive reports are flawed by methodologic imperfections or shortcomings. In addition, when positive findings were reported, no precise response pattern could be identified in a reproducible way. In particular, results from HTST studies tend to exclude the role of a cell stressor for exposure to RF fields at nonthermal intensities. However, on the basis of lessons from microwave-assisted chemistry, we can assume that RF fields might affect heat-sensitive gene or protein expression to an extent larger than would be predicted from temperature change only. But in all likelihood, this would concern intensities higher than those relevant to usual human exposure. The precise role of transcriptomics and proteomics in the screening of bioeffects from exposure to RF fields from mobile phones is still uncertain in view of the lack of positively identified phenotypic change and the lack of theoretical, as well as experimental, arguments for specific gene and/or protein response patterns after this kind of exposure.

  16. The dynamics of small molecules in intense laser fields

    NASA Astrophysics Data System (ADS)

    Posthumus, J. H.

    2004-05-01

    In the past decade, the understanding of the dynamics of small molecules in intense laser fields has advanced enormously. At the same time, the technology of ultra-short pulsed lasers has equally progressed to such an extent that femtosecond lasers are now widely available. This review is written from an experimentalist's point of view and begins by discussing the value of this research and defining the meaning of the word 'intense'. It continues with describing the Ti : sapphire laser, including topics such as pulse compression, chirped pulse amplification, optical parametric amplification, laser-pulse diagnostics and the absolute phase. Further aspects include focusing, the focal volume effect and space charge. The discussion of physics begins with the Keldysh parameter and the three regimes of ionization, i.e. multi-photon, tunnelling and over-the-barrier. Direct-double ionization (non-sequential ionization), high-harmonic generation, above-threshold ionization and attosecond pulses are briefly mentioned. Subsequently, a theoretical calculation, which solves the time-dependent Schrödinger equation, is compared with an experimental result. The dynamics of H_{2}^{ + } in an intense laser field is interpreted in terms of bond-softening, vibrational trapping (bond-hardening), below-threshold dissociation and laser-induced alignment of the molecular axis. The final section discusses the modified Franck-Condon principle, enhanced ionization at critical distances and Coulomb explosion of diatomic and triatomic molecules.

  17. Intense magnetic field generation by solidification and crustal delamination

    NASA Astrophysics Data System (ADS)

    Neufeld, J. A.; Bryson, J. F. J.; Nimmo, F.

    2015-12-01

    Recent paleomagnetic measurements of meteorites suggest that asteroidal magnetic fields are a common feature of the early solar system [1,2]. The iron cores of different asteroids may solidify in different ways [3]. For the IVA iron meteorite parent body the rapid cooling rates and correlation with Ni concentrations further suggest that their parent body was entirely metal, and that solidification of their parent asteroid proceeded from the top down. Here we present model constraints on the thermo-chemical evolution of such rapidly cooled iron asteroids. We show that the temperature of the liquid is rapidly well mixed, and equal to the composition-dependent freezing point, and that thermal convection contributes only at early times to generation of intense magnetic fields and is therefore not sufficient to explain the generation of a dynamo. Instead, we propose that viscous delamination [4] at the base of the solidifying, dense crust provides a sufficient buoyancy flux to generate a magnetic field with properties consistent with those inferred from paleomagnetic measurements of the two IVA meteorites [5]. A model that captures the aggregate effect of episodic delamination events predicts the evolution of the crust and the formation and growth of the asteroid core, the intensity and directional evolution of the magnetic field through time, and the times at which magnetic field generation ceases and total asteroid solidification occur. These predictions can be compared directly with recent measurements of IVA iron meteorites [5] with implications for top-down solidification, the solid structure of the IVA parent core, and magnetic field generation both on the IVA parent body, and wider implications for top-down core solidification generally. [1] Weiss et al. Space Sci. Rev. 152, 341-390 (2010). [2] Tarduno et al. Science. 338, 939-942 (2012). [3] Williams Earth Planet. Sci. Lett. 284, 564-569 (2009) [4] Molnar et al. Geophys. J. Int. 133, 568-584 (1998) [5] Bryson et

  18. Near-field radiofrequency electromagnetic exposure assessment.

    PubMed

    Rubtsova, Nina; Perov, Sergey; Belaya, Olga; Kuster, Niels; Balzano, Quirino

    2015-09-01

    Personal wireless telecommunication devices, such as radiofrequency (RF) electromagnetic field (EMF) sources operated in vicinity of human body, have possible adverse health effects. Therefore, the correct EMF assessment is necessary in their near field. According to international near-field measurement criteria, the specific absorption rate (SAR) is used for absorbed energy distribution assessment in tissue simulating liquid phantoms. The aim of this investigation is to validate the relationship between the H-field of incident EMF and absorbed energy in phantoms. Three typical wireless telecommunication system frequencies are considered (900, 1800 and 2450 MHz). The EMF source at each frequency is an appropriate half-wave dipole antenna and the absorbing medium is a flat phantom filled with the suitable tissue simulating liquid. Two methods for SAR estimation have been used: standard procedure based on E-field measured in tissue simulating medium and a proposed evaluation by measuring the incident H-field. Compared SAR estimations were performed for various distances between sources and phantom. Also, these research data were compared with simulation results, obtained by using finite-difference time-domain method. The acquired data help to determine the source near-field space characterized by the smallest deviation between SAR estimation methods. So, this region near the RF source is suitable for correct RF energy absorption assessment using the magnetic component of the RF fields.

  19. Palaeomagnetic field intensity variations suggest Mesoproterozoic inner-core nucleation.

    PubMed

    Biggin, A J; Piispa, E J; Pesonen, L J; Holme, R; Paterson, G A; Veikkolainen, T; Tauxe, L

    2015-10-08

    The Earth's inner core grows by the freezing of liquid iron at its surface. The point in history at which this process initiated marks a step-change in the thermal evolution of the planet. Recent computational and experimental studies have presented radically differing estimates of the thermal conductivity of the Earth's core, resulting in estimates of the timing of inner-core nucleation ranging from less than half a billion to nearly two billion years ago. Recent inner-core nucleation (high thermal conductivity) requires high outer-core temperatures in the early Earth that complicate models of thermal evolution. The nucleation of the core leads to a different convective regime and potentially different magnetic field structures that produce an observable signal in the palaeomagnetic record and allow the date of inner-core nucleation to be estimated directly. Previous studies searching for this signature have been hampered by the paucity of palaeomagnetic intensity measurements, by the lack of an effective means of assessing their reliability, and by shorter-timescale geomagnetic variations. Here we examine results from an expanded Precambrian database of palaeomagnetic intensity measurements selected using a new set of reliability criteria. Our analysis provides intensity-based support for the dominant dipolarity of the time-averaged Precambrian field, a crucial requirement for palaeomagnetic reconstructions of continents. We also present firm evidence for the existence of very long-term variations in geomagnetic strength. The most prominent and robust transition in the record is an increase in both average field strength and variability that is observed to occur between a billion and 1.5 billion years ago. This observation is most readily explained by the nucleation of the inner core occurring during this interval; the timing would tend to favour a modest value of core thermal conductivity and supports a simple thermal evolution model for the Earth.

  20. 60-Hertz electric-field exposures in transmission line towers.

    PubMed

    Bracken, T; Senior, Russell; Dudman, Joseph

    2005-09-01

    This article reports on an investigation of 60-Hz electric-field exposures of line workers in 230- to 765-kV transmission line towers. The exposures were based on computations of the unperturbed electric field along climbing routes and at work positions on the towers and on insulated ladders suspended in towers. Computed exposures were expressed in terms of the unperturbed electric field averaged over the body as stipulated by guidelines. For the realistic on-tower positions, the worker's posture, the uniformity of the field, and the field orientation differed from the guideline exposure scenario of standing erect in a vertical uniform field. These differences suggest the need for care in comparing electric-field exposures in towers with guideline limits. The unperturbed nonuniform fields at discrete points near steel and aluminum lattice structures were computed using Monte Carlo methods that model surface and spatial electric fields on and near standard geometrical elements. To estimate a whole-body average, fields were computed at 10 discrete points positioned on segments of an articulated stick-figure model of the human body. The whole-body average field was computed from fields at all the points weighted by the fraction of body volume that the corresponding segment represented. We estimated the average unperturbed electric field, the space potential at the torso, and the induced short-circuit current for 19 climbing and work positions in six towers. The maximum average electric-field exposure during climbing ranged from 10 kV/m for a 230-kV tower to 31 kV/m for a 765-kV tower. Exposures at on-tower work positions were lower than the estimated maximum exposures during climbing. For 500- and 765-kV towers, computed exposures while climbing and at some on-tower positions exceeded the limit of 20 kV/m given in the recently adopted IEEE Standard C95.6 2002. For lower voltage towers, exposures did not exceed 20 kV/m.

  1. Field assessment of an aluminum intensive passenger car

    SciTech Connect

    Cuenca, R.M.

    1994-12-31

    Ford Motor Co. has made a small batch of ``aluminum intensive vehicles`` (AIV), consisting of mid-size cars (Taurus/Sable) with all-aluminum bodies. The first twenty vehicles were made for internal evaluation at Ford, but the second batch of twenty has been placed on the hands of selected independent users, primarily automotive suppliers, for long term field assessment. The mass reduction achieved in the body of an AIV is shown, and compared with an equivalent standard steel body. Argonne obtained one of these vehicles last October; this is an assessment of the fuel consumption and other operational characteristics of this type of car to date.

  2. Intense Field-Matter Interactions: Multiple Ionization of Clusters

    SciTech Connect

    Snyder, E.M.; Buzza, S.A.; Castleman, A.W. Jr.

    1996-10-01

    We report the results for the production of highly charged atomic species (e.g., Xe{sup 20+}, Kr{sup 18+}, O{sup 5+}, and C{sup 4+}) resulting from the interaction of intense laser fields (up to {approximately}10{sup 15} W/cm{sup 2}) with atomic and multicenter molecular clusters. The processes are also investigated using ultrafast pump-probe techniques, showing distinct beating patterns for the ionization structure in the molecular system. A comparison of our results with predictions of several different theoretical models provides strong support for the ionization ignition mechanism. {copyright} {ital 1996 The American Physical Society.}

  3. DC response of hot carriers under circularly polarized intense microwave fields and intense magnetic fields in quantum wells

    SciTech Connect

    Ishida, Norihisa

    2013-12-04

    Hot carrier dynamics under intense microwave and crossed magnetic fields are investigated theoretically for the case that the dominant scattering process is inelastic collision, especially intersubband and intrasubband transition in Quantum wells. If the applied electric fields are circularly polarized, the equation of motion forms symmetric on the x-y plane. But the carrier motions are complicated to accumulate because of acceleration and emission process. This situation makes possible to create a variation of the carrier motion, typically the carrier bunching is occurred. This state is a sort of population inversion. The DC response of this system attains strongly negative at appropriate field conditions. Through the simulation for the real case described below, it may include a type of induced emission.

  4. Human disease resulting from exposure to electromagnetic fields.

    PubMed

    Carpenter, David O

    2013-01-01

    Electromagnetic fields (EMFs) include everything from cosmic rays through visible light to the electric and magnetic fields associated with electricity. While the high frequency fields have sufficient energy to cause cancer, the question of whether there are human health hazards associated with communication radiofrequency (RF) EMFs and those associated with use of electricity remains controversial. The issue is more important than ever given the rapid increase in the use of cell phones and other wireless devices. This review summarizes the evidence stating that excessive exposure to magnetic fields from power lines and other sources of electric current increases the risk of development of some cancers and neurodegenerative diseases, and that excessive exposure to RF radiation increases risk of cancer, male infertility, and neurobehavioral abnormalities. The relative impact of various sources of exposure, the great range of standards for EMF exposure, and the costs of doing nothing are also discussed.

  5. Effect of intense laser IR fields on triatomic molecules

    NASA Astrophysics Data System (ADS)

    Ivanov, S. V.; Panchenko, V. Ia.; Chugunov, A. V.

    1986-04-01

    Theoretical and experimental results on the effect of intense laser IR fields on triatomic molecular gases are presented with particular emphasis on ozone. Experiments were conducted in single- and double-frequency IR fields at power densities ranging from 10 to the -6th to 10 GW/sq cm in the pulsed regime and 0.001 to 100 W/sq cm in the CW regime; studies were performed using a TEA CO2 laser system. Attention is given to: the nonlinear absorption spectrum; the dependence of absorption in ozone on the power density of incident radiation; results of numerical solutions; the analytical solution; two-photon resonances in the ozone absorption spectrum; the spectrum of double-frequency IR-IR absorption; cascade-excitation channels; and laser-stimulated explosion in ozone.

  6. Exposure scheme separates effects of electric shock and electric field for honey bees, Apis mellifera L

    SciTech Connect

    Bindokas, V.P.; Gauger, J.R.; Greenberg, B.

    1988-01-01

    Mechanisms to explain disturbance of honey bee colonies under a 765-kV, 60-Hz transmission line (electric (E) field = 7 kV/m) fall into two categories: direct bee perception of enhanced in-hive E fields, and perception of shock from induced currents. The same adverse biological effects previously observed in honey bee colonies exposed under a 765-kV transmission line can be reproduced by exposing worker bees to shock or E field within elongated hive entranceways (= tunnels). Exposure to intense E field caused disturbance only if bees were in contact with a conductive substrate. E-field and shock exposure can be separated and precisely defined within tunnels, eliminating dosimetric vagaries that occur when entire hives are exposed to E field.

  7. Estimating worker exposure to power-frequency magnetic fields

    SciTech Connect

    Wenzl, T.B.

    1992-01-01

    For a case-control study of brain cancer at a large automobile transmission plant, a strategy was developed to use two types of instruments to measure personal exposure to power-frequency magnetic fields. A representative group of 81 workers were asked to wear a data-logging dosimeter for one-half shift apiece. This instrument recorded 3-axis magnetic field values every 4 seconds. With little clarity about the biologic process which might connect these magnetic fields to cancer promotion, several indices summarizing exposure variability over time were computed. A new index of [open quotes]jaggedness[close quotes] was also computed, since some human studies suggest very uneven exposure profiles are the most biologically active, possibly via interference with melatonin synthesis in the pineal gland. Comparisons between the several exposure indices showed moderately high correlations between indices which were sensitive to peak exposures, but other indices were less well correlated. To test a simpler measurement strategy, a hand-held direct reading instrument was also used, with multiple measurements taken at the head and waist for most workstations. These were averaged and combined with time estimates to give[open quote] built-up[close quote] average exposures. Correlations were high (r = 0.8) between these built-up averages and averages derived from the datalogger records. It was possible to assign job titles to three distinct exposure categories based on measures of the central tendency of the distributions of measured exposures. By ranking job groups by their average exposures, electricians and non-production grinders were placed in a high exposure category, assemblers and material handlers were placed in a low category, and all other jobs were placed in a medium exposure category. Analysis of variance, with influence analysis, was used to determine that these categories had significant exposure differences from one another.

  8. Electromagnetic cascades and the depletion of intense fields

    NASA Astrophysics Data System (ADS)

    Bulanov, Stepan; Seipt, Daniel; Heinzl, Thomas; Marklund, Mattias; Ji, Qing; Steinke, Sven; Schroeder, Carl; Esarey, Eric; Leemans, Wim P.

    2016-10-01

    The interaction of electrons, positrons, and photons with intense electromagnetic fields gives rise to multi-photon Compton and Breit-Wheeler processes. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution. Moreover the multi-photon nature of Compton and Breit-Wheeler processes implies the absorption of a significant number of photons. As a result, the interaction of a highly charged electron bunch with an intense laser pulse can lead to a significant depletion of the laser pulse energy, thus rendering the external field approximation invalid. The relevance of these results to the proposed BELLA-i beamline at BELLA center at LBNL is discussed. We acknowledge support from the Office of Science of the US DOE under Contract No. DE-AC02-05CH11231.

  9. Analyses of magnetic-field peak-exposure summary measures.

    PubMed

    Mezei, Gabor; Bracken, T Dan; Senior, Russell; Kavet, Robert

    2006-11-01

    Two previous epidemiologic studies reported an association between the maximum magnetic field exposure logged during a 24-h measurement period and risk of miscarriage. A hypothesis was put forth which argued that the observed association may be the result of behavioral differences between women with healthy pregnancies (less physically active) and women with miscarriage. We analyzed four existing data sets with power-frequency magnetic-field personal exposure (PE) measurements to investigate the characteristics of peak-exposure measures. We found that the value of the measured maximum magnetic-field exposure varied inversely with the sampling interval between magnetic-field measurements and that maximum values demonstrated less stability over time in repeated measurements, compared to time-weighted average and 95th and 99th -percentile values. We also found that the number of activity categories entered by study subjects could be used to estimate the proportion of subjects with exposure above various threshold values. Exposure metrics based on maximum values exceeding thresholds tend to classify active people into higher exposure categories. These findings are consistent with the hypothesis suggesting that the association between maximum magnetic fields and miscarriage are possibly the result of behavioral differences between women with healthy pregnancies and women who experience miscarriages. Thus, generalization from a given study to more global exposure characterization should be made with particular caution and with due consideration to sampling interval and other characteristics of the measurement protocol potentially influencing the measured maximum. Future epidemiologic studies of peak magnetic field exposure and spontaneous abortion should carefully evaluate the potential confounding effect of the women's activity level during pregnancy.

  10. Gigagauss magnetic field generation from high intensity laser solid interactions

    SciTech Connect

    Cowan, T; Moran, M; Hammer, J; Hatchett, S; Hunt, A; Key, M H; Langdon, A B; Lasinski, B F; Pennington, D; Perry, M D; Sefcik, J A; Snavely, R; Trebes, J; Wilks, S C

    1998-10-15

    Intense laser (>1021 W/cm2 ) sources using pulse compression techniques in the sub-picosecond time frame have been used to create dynamic electric field strenghs in excess of 100 Megavolts/micron with associated magnetic field strengths in the Gigagauss regime. We have begun a series of experiments using the Petawatt Laser system at LLNL to determine the potential of these sources for a variety of applications. Hot electron spectra from laser-target interactions in Au have been measured with energies up to 100 MeV. Hot x-ray production has been measured using filtered thermoluminescent dosimeters and threshold nuclear activation ({gamma},n) from giant resonance interactions. High resolution radiographs through a {rho}r > 165 gm/cm² have been obtained. Dose levels in the x-ray band from 2-8 MeV have been measured at the level of several Rads at one meter from the target for a single pulse. The physics of these sources and the scaling relationships and laser technology required to provide high magnetic fields will be discussed. Results of preliminary magnetic field calculations will be presented along with potential applications of this technology and estimates of the fundamental scaling limits for future development.

  11. Chronic exposure to ELF fields may induce depression

    SciTech Connect

    Wilson, B.W.

    1988-01-01

    Exposure to extremely-low-frequency (ELF) electric or magnetic fields has been postulated as a potentially contributing factor in depression. Epidemiologic studies have yielded positive correlations between magnetic- and/or electric-field strengths in local environments and the incidence of depression-related suicide. Chronic exposure to ELF electric or magnetic fields can disrupt normal circadian rhythms in rat pineal serotonin-N-acetyltransferase activity as well as in serotonin and melatonin concentrations. Such disruptions in the circadian rhythmicity of pineal melatonin secretion have been associated with certain depressive disorders in human beings. In the rat, ELF fields may interfere with tonic aspects of neuronal input to the pineal gland, giving rise to what may be termed functional pinealectomy. If long-term exposure to ELF fields causes pineal dysfunction in human beings as it does in the rat, such dysfunction may contribute to the onset of depression or may exacerbate existing depressive disorders. 85 references.

  12. Magnetic field exposure in a nondestructive testing operation.

    PubMed

    Lippert, Julia F; Lacey, Steven E; Kennedy, Kathleen J; Esmen, Nurtan A; Buchanich, Jeanine M; Marsh, Gary M

    2007-01-01

    Nondestructive testing is any technique used to inspect the integrity of a manufactured item without diminishing its future usefulness. Magnetic particle inspection is one type of nondestructive testing that uses electromagnetism in the inspection procedure, thus potentially exposing the operator to magnetic fields. During magnetic particle inspection, investigators took peak magnetic field measurements of 8 turbine engine shafts at a turbine engine overhaul and repair center. They recorded 95 peak magnetic field measurements, ranging from < 0.1 to 29.27 mT. The exposure values measured were among the highest reported in the occupational setting. Further work is needed to characterize magnetic field exposures in magnetic particle inspection operations--in particular, by differentiating magnetic field magnitude by current frequency--and to understand exposure as it relates to different types of magnetic particle inspection devices.

  13. Office worker exposure to extremely low frequency magnetic fields

    SciTech Connect

    Hiebert, D.G.

    1994-05-01

    A study of office worker exposure to extremely low frequency magnetic fields (ELF MF) was conducted at Los Alamos National Laboratory. The main purpose of this study was to quantitatively assess ELF MF exposures. A secondary objective was to determine whether or not exposures to ELF MF can be reduced by implementing administrative controls and educating workers on the sources of such fields. EMDEX dosimeters were used to determine full shift personal exposures for 12 volunteers from two personnel sections and one training section. In addition, using the EMDEX meter in survey mode, office area evaluations were conducted. Administrative controls and training were implemented in an attempt to reduce exposures. Post control monitoring was conducted to determine if a reduction in ELF MF occurred among the workers. On average, baseline office worker exposures to ELF MF were 2.3 mG, ranging from 0.6 to 9.7 mG. The post control exposures averaged 1.1 mG with a range from 0.5 to 2.2 mG. A reduction of 53% overall was seen after implementation of administrative controls and training. The office area survey indicated that many sources of ELF MF influence exposure and that magnetic field strengths vary not only from one type of equipment to another, but also vary between two similar pieces of equipment.

  14. Technical brief: Constant intense light exposure to lesion and initiate regeneration in normally pigmented zebrafish.

    PubMed

    Rajaram, Kamya; Summerbell, Emily R; Patton, James G

    2014-01-01

    Zebrafish are capable of robust and spontaneous regeneration of injured retina. Constant intense light exposure to adult albino zebrafish specifically causes apoptosis of rod and cone photoreceptor cells and is an excellent model to study the molecular mechanisms underlying photoreceptor regeneration. However, this paradigm has only been applied to lesion zebrafish of the nonpigmented albino genetic background, which precludes the use of numerous transgenic reporter lines that are widely used to study regeneration. Here, we explored the effectiveness of constant intense light exposure in causing photoreceptor apoptosis and stimulating regeneration in normally pigmented zebrafish retinas. We show that constant intense light exposure causes widespread photoreceptor damage in the dorsal-central retinas of pigmented zebrafish. Photoreceptor loss triggers dedifferentiation and proliferation of Müller glia as well as progenitor cell proliferation. We also demonstrate that the timeline of regeneration response is comparable between the albino and the pigmented retinas.

  15. Technical brief: Constant intense light exposure to lesion and initiate regeneration in normally pigmented zebrafish

    PubMed Central

    Rajaram, Kamya; Summerbell, Emily R.

    2014-01-01

    Zebrafish are capable of robust and spontaneous regeneration of injured retina. Constant intense light exposure to adult albino zebrafish specifically causes apoptosis of rod and cone photoreceptor cells and is an excellent model to study the molecular mechanisms underlying photoreceptor regeneration. However, this paradigm has only been applied to lesion zebrafish of the nonpigmented albino genetic background, which precludes the use of numerous transgenic reporter lines that are widely used to study regeneration. Here, we explored the effectiveness of constant intense light exposure in causing photoreceptor apoptosis and stimulating regeneration in normally pigmented zebrafish retinas. We show that constant intense light exposure causes widespread photoreceptor damage in the dorsal-central retinas of pigmented zebrafish. Photoreceptor loss triggers dedifferentiation and proliferation of Müller glia as well as progenitor cell proliferation. We also demonstrate that the timeline of regeneration response is comparable between the albino and the pigmented retinas. PMID:25324680

  16. Small animal electric and magnetic field exposure systems. Final report

    SciTech Connect

    Patterson, R.C.; Dietrich, F.M.

    1993-10-01

    Laboratory evaluation of electric and magnetic fields (EMF) and cancer in animals requires exposure of relatively large numbers of animals, usually rats or mice, to 60-Hz fields under very well controlled conditions for periods of up to two years. This report describes two exposure systems, the first of which is based on modifications of an existing electric field exposure system to include magnetic field exposure capability. In this system, each module houses 576--768 mice, which can be exposed to electric field levels of up to 100 kV/m and magnetic field levels of up to 10 Gauss. When a module was operated at 10 Gauss, measured levels of noise and vibration fell substantially below the detection threshold for humans. Moreover, temperature rise in the coils did not exceed 12{degrees}C at the 10 Gauss level. Specifications and test results for the second system, which provides magnetic field exposure capability only, are similar, except that each module houses 624--780 mice. After installation of the second system at the West Los Angeles Veterans Medical Center in Los Angeles, California, additional results were obtained. This report provides a complete description of the engineering design, specifications, and test results for the completed systems.

  17. Magnetic field exposures in an automobile transmission plant.

    PubMed

    Wenzl, T B; Kriebel, D; Eisen, E A; Tolbert, P; Hallock, M

    1997-01-01

    Inconsistent findings from recent mortality studies of workers exposed to magnetic fields have led to calls for more detailed understanding of exposure distributions and metrics in various industries. The authors undertook personal monitoring at an automobile transmission plant to (a) learn if magnetic field exposure differences were present, (b) make assignments for a brain cancer study, and (c) compare two exposure indices. A wide range of average exposures occurred (i.e., 0.016-4.6 microtesla). Within-day variability was also large, and it reached 4 orders of magnitude for some workers. Unexpectedly, demagnetizers were found among the strong sources that contributed to elevated exposures. The authors used conventional summary measures to assign job groups to exposure categories, and they used a new index of exposure irregularity to make alternative assignments. These new assignments appeared to differ from the original ones with respect to work time in each exposure group (i.e., 54% of the work time fell into different exposure categories).

  18. Apoptotic cell death during Drosophila oogenesis is differentially increased by electromagnetic radiation depending on modulation, intensity and duration of exposure.

    PubMed

    Sagioglou, Niki E; Manta, Areti K; Giannarakis, Ioannis K; Skouroliakou, Aikaterini S; Margaritis, Lukas H

    2016-01-01

    Present generations are being repeatedly exposed to different types and doses of non-ionizing radiation (NIR) from wireless technologies (FM radio, TETRA and TV stations, GSM and UMTS phones/base stations, Wi-Fi networks, DECT phones). Although there is controversy on the published data regarding the non-thermal effects of NIR, studies have convincingly demonstrated bioeffects. Their results indicate that modulation, intensity, exposure duration and model system are important factors determining the biological response to irradiation. Attempting to address the dependence of NIR bioeffectiveness on these factors, apoptosis in the model biological system Drosophila melanogaster was studied under different exposure protocols. A signal generator was used operating alternatively under Continuous Wave (CW) or Frequency Modulation (FM) emission modes, at three power output values (10 dB, 0, -10 dB), under four carrier frequencies (100, 395, 682, 900 MHz). Newly emerged flies were exposed either acutely (6 min or 60 min on the 6th day), or repeatedly (6 min or 60 min daily for the first 6 days of their life). All exposure protocols resulted in an increase of apoptotic cell death (ACD) observed in egg chambers, even at very low electric field strengths. FM waves seem to have a stronger effect in ACD than continuous waves. Regarding intensity and temporal exposure pattern, EMF-biological tissue interaction is not linear in response. Intensity threshold for the induction of biological effects depends on frequency, modulation and temporal exposure pattern with unknown so far mechanisms. Given this complexity, translating such experimental data into possible human exposure guidelines is yet arbitrary.

  19. An industrial radiography exposure device based on measurement of transmitted gamma-ray intensity

    NASA Astrophysics Data System (ADS)

    Polee, C.; Chankow, N.; Srisatit, S.; Thong-Aram, D.

    2015-05-01

    In film radiography, underexposure and overexposure may happen particularly when lacking information of specimen material and hollowness. This paper describes a method and a device for determining exposure in industrial gamma-ray radiography based on quick measurement of transmitted gamma-ray intensity with a small detector. Application software was developed for Android mobile phone to remotely control the device and to display counting data via Bluetooth communication. Prior to film exposure, the device is placed behind a specimen to measure transmitted intensity which is inversely proportional to the exposure. Unlike in using the conventional exposure curve, correction factors for source decay, source-to- film distance, specimen thickness and kind of material are not needed. The developed technique and device make radiographic process economic, convenient and more reliable.

  20. OCCUPATIONAL EXPOSURE OF NMR SPECTROMETRISTS TO STATIC AND RADIOFREQUENCY FIELDS.

    PubMed

    Berlana, Tania; Úbeda, Alejandro

    2017-05-04

    Occupational exposure to static and radiofrequency fields emitted by nuclear magnetic resonance spectrometers was assessed through systematic field metering during operation of 19 devices in nine research centers. Whereas no measurable levels of radiofrequency radiation were registered outside the spectrometers, significant exposure to static field was detected, with maximum values recorded at the user's hand (B = 683.00 mT) and head-thorax (B = 135.70 mT) during spectrometer manipulation. All values were well below the exposure limits set by the European standard for workers protection against the effects of acute field exposure only. As for potential effects of chronic exposure, waiting for more complete knowledge, adoption of technical and operational strategies for exposure minimizing is advisable. In this respect, the data revealed that compared with standard magnetic shielding, ultrashield technology allows a 20-65-fold reduction of the field strength received by the operator. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. Representative electromagnetic field intensities near the Clam Lake, Wisconsin and Republic, Michigan ELF (Extremely Low Frequency) facilities

    NASA Astrophysics Data System (ADS)

    1984-01-01

    Extremely low frequency electromagnetic fields produced by ELF antennas and commercial power lines at Clam Lake, WI, and by commercial power lines at Republic, MI, have been measured at residences, businesses and forest recreational areas for the continuing assessment of the Navy's ELF Communications Program. The ELF fields from existing antennas at Clam Lake, and from power lines in both states are low. Introducing ELF antenna fields at Republic, MI in several years will not significantly change the electromagnetic environment there. The existing field intensities are interpreted and compared with independent expert, judgment, professional standards-setting and judicial and administrative law opinions regarding safe exposure of the public to ELF electromagnetic fields.

  2. Dissociation dynamics of diatomic molecules in intense fields

    NASA Astrophysics Data System (ADS)

    Magrakvelidze, Maia

    We study the dynamics of diatomic molecules (dimers) in intense IR and XUV laser fields theoretically and compare the results with measured data in collaboration with different experimental groups worldwide. The first three chapters of the thesis cover the introduction and the background on solving time-independent and time-dependent Schrodinger equation. The numerical results in this thesis are presented in four chapters, three of which are focused on diatomic molecules in IR fields. The last one concentrates on diatomic molecules in XUV pulses. The study of nuclear dynamics of H2 or D2 molecules in IR pulses is given in Chapter 4. First, we investigate the optimal laser parameters for observing field-induced bond softening and bond hardening in D2+. Next, the nuclear dynamics of H2 + molecular ions in intense laser fields are investigated by analyzing their fragment kinetic-energy release (KER) spectra as a function of the pump-probe delay τ Lastly, the electron localization is studied for long circularly polarized laser pulses. Chapter 5 covers the dissociation dynamics of O2+ in an IR laser field. The fragment KER spectra are analyzed as a function of the pump-probe delay τ Within the Born-Oppenheimer approximation, we calculate ab-initio adiabatic potential-energy curves and their electric dipole couplings, using the quantum chemistry code GAMESS. In Chapter 6, the dissociation dynamics of the noble gas dimer ions He 2+, Ne2+, Ar2 +, Kr2+, and Xe2 + is investigated in ultrashort pump and probe laser pulses of different wavelengths. We observe a striking "delay gap" in the pump-probe-delay-dependent KER spectrum only if the probe-pulse wavelength exceeds the pump-pulse wavelength. Comparing pump-probe-pulse-delay dependent KER spectra for different noble gas dimer cations, we quantitatively discuss quantum-mechanical versus classical aspects of the nuclear vibrational motion as a function of the nuclear mass. Chapter 7 focuses on diatomic molecules in XUV

  3. Fetal exposure to low frequency electric and magnetic fields

    NASA Astrophysics Data System (ADS)

    Cech, R.; Leitgeb, N.; Pediaditis, M.

    2007-02-01

    To investigate the interaction of low frequency electric and magnetic fields with pregnant women and in particular with the fetus, an anatomical voxel model of an 89 kg woman at week 30 of pregnancy was developed. Intracorporal electric current density distributions due to exposure to homogeneous 50 Hz electric and magnetic fields were calculated and results were compared with basic restrictions recommended by ICNIRP guidelines. It could be shown that the basic restriction is met within the central nervous system (CNS) of the mother at exposure to reference level of either electric or magnetic fields. However, within the fetus the basic restriction is considerably exceeded. Revision of reference levels might be necessary.

  4. Prenatal Versus Postnatal Tobacco Smoke Exposure and Intensive Care Use in Children Hospitalized With Bronchiolitis.

    PubMed

    Stevenson, Michelle D; Mansbach, Jonathan M; Mowad, Eugene; Dunn, Michelle; Clark, Sunday; Piedra, Pedro A; Sullivan, Ashley F; Camargo, Carlos A

    2016-07-01

    Among children hospitalized with bronchiolitis, we examined the associations between in utero exposure to maternal cigarette smoking, postnatal tobacco smoke exposure, and risk of admission to the intensive care unit (ICU). We performed a 16-center, prospective cohort study of hospitalized children aged <2 years with a physician admitting diagnosis of bronchiolitis. For 3 consecutive years, from November 1, 2007 until March 31, 2010, site teams collected data from participating families, including information about prenatal maternal smoking and postnatal tobacco exposure. Analyses used chi-square, Fisher's exact, and Kruskal-Wallis tests and multivariable logistic regression. Among 2207 enrolled children, 216 (10%) had isolated in utero exposure to maternal smoking, 168 (8%) had isolated postnatal tobacco exposure, and 115 (5%) experienced both. Adjusting for age, sex, race, birth weight, viral etiology, apnea, initial severity of retractions, initial oxygen saturation, oral intake, and postnatal tobacco exposure, children with in utero exposure to maternal smoking had greater odds of being admitted to the ICU (adjusted odds ratio [aOR] 1.51, 95% confidence interval [CI] 1.14-2.00). Among children with in utero exposure to maternal smoking, those with additional postnatal tobacco exposure had a greater likelihood of ICU admission (aOR 1.95, 95% CI 1.13-3.37) compared to children without postnatal tobacco smoke exposure (aOR 1.47, 95% CI 1.05-2.04). Maternal cigarette smoking during pregnancy puts children hospitalized with bronchiolitis at significantly higher risk of intensive care use. Postnatal tobacco smoke exposure may exacerbate this risk. Health care providers should incorporate this information into counseling messages. Copyright © 2016 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

  5. Exposure time-dependent thermal effects of radiofrequency electromagnetic field exposure on the whole body of rats.

    PubMed

    Ohtani, Shin; Ushiyama, Akira; Maeda, Machiko; Hattori, Kenji; Kunugita, Naoki; Wang, Jianqing; Ishii, Kazuyuki

    2016-01-01

    We investigated the thermal effects of radiofrequency electromagnetic fields (RF-EMFs) on the variation in core temperature and gene expression of some stress markers in rats. Sprague-Dawley rats were exposed to 2.14 GHz wideband code division multiple access (W-CDMA) RF signals at a whole-body averaged specific absorption rate (WBA-SAR) of 4 W/kg, which causes behavioral disruption in laboratory animals, and 0.4 W/kg, which is the limit for the occupational exposure set by the International Commission on Non-Ionizing Radiation Protection guideline. It is important to understand the possible in vivo effects derived from RF-EMF exposures at these intensities. Because of inadequate data on real-time core temperature analyses using free-moving animal and the association between stress and thermal effects of RF-EMF exposure, we analyzed the core body temperature under nonanesthetic condition during RF-EMF exposure. The results revealed that the core temperature increased by approximately 1.5°C compared with the baseline and reached a plateau till the end of RF-EMF exposure. Furthermore, we analyzed the gene expression of heat-shock proteins (Hsp) and heat-shock transcription factors (Hsf) family after RF-EMF exposure. At WBA-SAR of 4 W/kg, some Hsp and Hsf gene expression levels were significantly upregulated in the cerebral cortex and cerebellum following exposure for 6 hr/day but were not upregulated after exposure for 3 hr/day. On the other hand, there was no significant change in the core temperature and gene expression at WBA-SAR of 0.4 W/kg. Thus, 2.14-GHz RF-EMF exposure at WBA-SAR of 4 W/kg induced increases in the core temperature and upregulation of some stress markers, particularly in the cerebellum.

  6. A comparative evaluation of three hydrophones and a numerical model in high intensity focused ultrasound fields.

    PubMed

    Haller, Julian; Jenderka, Klaus-Vitold; Durando, Gianni; Shaw, Adam

    2012-02-01

    The pressure fields of two different high intensity focused ultrasound (HIFU) transducers operated in burst mode were measured at acoustical power levels of 25 and 50 W (continuous wave equivalent) with three different hydrophones: A fiber-optic displacement sensor, a commercial HIFU needle hydrophone, and a prototype of a membrane hydrophone with a protective coating against cavitation effects. Additionally, the fields were modeled using a freely available simulations software package. The measured waveforms, the peak pressure profiles, as well as the spatial-peak temporal-average intensities from the different devices and from the modeling are compared and possible reasons for differences are discussed. The results clearly show that reliable pressure measurements in HIFU fields remain a difficult task concerning both the reliability of the measured values and the robustness of the sensors used: Only the fiber-optic hydrophone survived all four exposure regimes and the measured spatial-peak temporal-average intensities varied by a factor of up to 1.5 between the measurements and the modeling and between the measurements among themselves.

  7. Absence of acute ocular damage in humans after prolonged exposure to intense RF EMF

    NASA Astrophysics Data System (ADS)

    Adibzadeh, F.; van Rhoon, G. C.; Verduijn, G. M.; Naus-Postema, N. C.; Paulides, M. M.

    2016-01-01

    The eye is considered to be a critical organ when determining safety standards for radio frequency (RF) radiation. Experimental data obtained using animals showed that RF heating of the eye, particularly over a specific threshold, can induce cataracts. During the treatment of cancer in the head and neck by hyperthermia, the eyes receive a considerable dose of RF radiation due to stray radiation from the prolonged (60 min) and intense exposure at 434 MHz of this region. In the current study, we verified the exposure guidelines for humans by determining the association between the electromagnetic and thermal dose in the eyes with the reported ocular effects. We performed a simulation study to retrospectively assess the specific absorption rate (SAR) and temperature increase in the eyes of 16 selected patients (encompassing a total of 74 treatment sessions) whose treatment involved high power delivery as well as a minimal distance between the tumor site and the eye. Our results show that the basic restrictions on the peak 10 g spatial-averaged SAR (10 W kg-1) and peak tissue temperature increase (1 °C) are exceeded by up to 10.4 and 4.6 times, on average, and by at least 6.2 and 1.8 times when considering the lower limit of the 95% confidence interval. Evaluation of the acute effects according to patients’ feedback (all patients), the common toxicity criteria scores (all patients) and an ophthalmology investigation (one patient with the highest exposure) revealed no indication of any serious acute ocular effect, even though the eyes were exposed to high electromagnetic fields, leading to a high thermal dose. We also found that, although there is a strong correlation (R 2  =  0.88) between the predicted induced SAR and temperature in the eye, there are large uncertainties regarding the temperature-SAR relationship. Given this large uncertainty (129%) compared with the uncertainty of 3D temperature simulations (61%), we recommend using temperature

  8. Absence of acute ocular damage in humans after prolonged exposure to intense RF EMF.

    PubMed

    Adibzadeh, F; van Rhoon, G C; Verduijn, G M; Naus-Postema, N C; Paulides, M M

    2016-01-21

    The eye is considered to be a critical organ when determining safety standards for radio frequency (RF) radiation. Experimental data obtained using animals showed that RF heating of the eye, particularly over a specific threshold, can induce cataracts. During the treatment of cancer in the head and neck by hyperthermia, the eyes receive a considerable dose of RF radiation due to stray radiation from the prolonged (60 min) and intense exposure at 434 MHz of this region. In the current study, we verified the exposure guidelines for humans by determining the association between the electromagnetic and thermal dose in the eyes with the reported ocular effects. We performed a simulation study to retrospectively assess the specific absorption rate (SAR) and temperature increase in the eyes of 16 selected patients (encompassing a total of 74 treatment sessions) whose treatment involved high power delivery as well as a minimal distance between the tumor site and the eye. Our results show that the basic restrictions on the peak 10 g spatial-averaged SAR (10 W kg(-1)) and peak tissue temperature increase (1 °C) are exceeded by up to 10.4 and 4.6 times, on average, and by at least 6.2 and 1.8 times when considering the lower limit of the 95% confidence interval. Evaluation of the acute effects according to patients' feedback (all patients), the common toxicity criteria scores (all patients) and an ophthalmology investigation (one patient with the highest exposure) revealed no indication of any serious acute ocular effect, even though the eyes were exposed to high electromagnetic fields, leading to a high thermal dose. We also found that, although there is a strong correlation (R (2) =  0.88) between the predicted induced SAR and temperature in the eye, there are large uncertainties regarding the temperature-SAR relationship. Given this large uncertainty (129%) compared with the uncertainty of 3D temperature simulations (61%), we recommend using temperature simulations as a

  9. Electric and magnetic field exposures for people living near a 735-kilovolt power line.

    PubMed Central

    Levallois, P; Gauvin, D; St-Laurent, J; Gingras, S; Deadman, J E

    1995-01-01

    The purpose of this study was to assess the effect of a 735-kV transmission line on the electric and magnetic field exposures of people living at the edge of the line's right of way. Exposure of 18 adults, mostly white-collar workers, living in different bungalows located 190-240 feet from the line (exposed subjects) was compared to that of 17 adults living in similar residences far away from any transmission line. Each subject carried a Positron meter for 24 hr during 1 workday, which measured 60-Hz electric and magnetic fields every minute. All measurements were carried out in parallel for exposed and unexposed subjects during the same weeks between September and December. During measurements the average loading on the line varied between 600 and 1100 A. The average magnetic field intensity while at home was 4.4 times higher among exposed subjects than unexposed (7.1 versus 1.6 mG, p = 0.0001) and 6.2 times higher when considering only the sleeping period (6.8 versus 1.1 mG, p = 0.0001). Based on the 24-hr measurement, average magnetic field exposure was three times higher among the exposed. Electric field intensity was also higher among the exposed while at home (26.3 versus 14.0 V/m, p = 0.03). Magnetic field intensity among the exposed was positively correlated with the loading on the line (r = 0.8, p = 0.001). Percentage of time above a magnetic field threshold (2 mG or 7.8 mG) was a good indicator to distinguish the two types of exposure.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 1. PMID:7498095

  10. Compliance with High-Intensity Radiated Fields Regulations - Emitter's Perspective

    NASA Technical Reports Server (NTRS)

    Statman, Joseph; Jamnejad, Vahraz; Nguyen, Lee

    2012-01-01

    NASA's Deep Space Network (DSN) uses high-power transmitters on its large antennas to communicate with spacecraft of NASA and its partner agencies. The prime reflectors of the DSN antennas are parabolic, at 34m and 70m in diameter. The DSN transmitters radiate Continuous Wave (CW) signals at 20 kW - 500 kW at X-band and S-band frequencies. The combination of antenna reflector size and high frequency results in a very narrow beam with extensive oscillating near-field pattern. Another unique feature of the DSN antennas is that they (and the radiated beam) move mostly at very slow sidereal rate, essentially identical in magnitude and at the opposite direction of Earth rotation.The DSN is in the process of revamping its documentation to provide analysis of the High Intensity Radiation Fields (HIRF) environment resulting from radio frequency radiation from DSN antennas for comparison to FAA regulations regarding certification of HIRF protection as outlined in the FAA regulations on HIRF protection for aircraft electrical and electronic systems (Title 14, Code of Federal Regulations (14 CFR) [section sign][section sign] 23.1308, 25.1317, 27.1317, and 29.1317).This paper presents work done at JPL, in consultation with the FAA. The work includes analysis of the radiated field structure created by the unique DSN emitters (combination of transmitters and antennas) and comparing it to the fields defined in the environments in the FAA regulations. The paper identifies areas that required special attention, including the implications of the very narrow beam of the DSN emitters and the sidereal rate motion. The paper derives the maximum emitter power allowed without mitigation and the mitigation zones, where required.Finally, the paper presents summary of the results of the analyses of the DSN emitters and the resulting DSN process documentation.

  11. Compliance with High-Intensity Radiated Fields Regulations - Emitter's Perspective

    NASA Technical Reports Server (NTRS)

    Statman, Joseph; Jamnejad, Vahraz; Nguyen, Lee

    2012-01-01

    NASA's Deep Space Network (DSN) uses high-power transmitters on its large antennas to communicate with spacecraft of NASA and its partner agencies. The prime reflectors of the DSN antennas are parabolic, at 34m and 70m in diameter. The DSN transmitters radiate Continuous Wave (CW) signals at 20 kW - 500 kW at X-band and S-band frequencies. The combination of antenna reflector size and high frequency results in a very narrow beam with extensive oscillating near-field pattern. Another unique feature of the DSN antennas is that they (and the radiated beam) move mostly at very slow sidereal rate, essentially identical in magnitude and at the opposite direction of Earth rotation.The DSN is in the process of revamping its documentation to provide analysis of the High Intensity Radiation Fields (HIRF) environment resulting from radio frequency radiation from DSN antennas for comparison to FAA regulations regarding certification of HIRF protection as outlined in the FAA regulations on HIRF protection for aircraft electrical and electronic systems (Title 14, Code of Federal Regulations (14 CFR) [section sign][section sign] 23.1308, 25.1317, 27.1317, and 29.1317).This paper presents work done at JPL, in consultation with the FAA. The work includes analysis of the radiated field structure created by the unique DSN emitters (combination of transmitters and antennas) and comparing it to the fields defined in the environments in the FAA regulations. The paper identifies areas that required special attention, including the implications of the very narrow beam of the DSN emitters and the sidereal rate motion. The paper derives the maximum emitter power allowed without mitigation and the mitigation zones, where required.Finally, the paper presents summary of the results of the analyses of the DSN emitters and the resulting DSN process documentation.

  12. Suppression of experimental allergic encephalomyelitis is specific to the frequency and intensity of nocturnally applied, intermittent magnetic fields in rats.

    PubMed

    Cook, L L; Persinger, M A

    2000-10-13

    Female Lewis rats (n=72) were inoculated with an emulsion of spinal cord and complete Freund's adjuvant. They were then exposed for approximately 6 min every hour between midnight and 08:00 h for 2 weeks to either 7 or 40 Hz amplitude-modulated magnetic fields whose temporal pattern was designed to simulate a (geomagnetic) storm sudden commencement. The peak strengths of the fields averaged between either 30-50 nT (low intensity) or 500 nT (high intensity). Rats exposed to the 7 Hz, low intensity magnetic fields displayed significantly less severe overt signs of experimental allergic encephalomyelitis than rats exposed to either of the two intensities of the 40 Hz fields, the high intensity 7 Hz field, or the reference (<10 nT) condition. The latter groups did not differ significantly from each other. Predicted severity based upon the numbers of foci of infiltrations of lymphocytes within the brains of the rats also demonstrated the ameliorating effects of the low intensity, 7 Hz exposures. These results suggest very specific characteristics of complex, weak magnetic fields within the sleeping environment could affect the symptoms of autoimmunity.

  13. Multifunctional plasmonic film for recording near-field optical intensity.

    PubMed

    Roxworthy, Brian J; Bhuiya, Abdul M; Inavalli, V V G Krishna; Chen, Hao; Toussaint, Kimani C

    2014-08-13

    We demonstrate the plasmonic equivalent of photographic film for recording optical intensity in the near field. The plasmonic structure is based on gold bowtie nanoantenna arrays fabricated on SiO2 pillars. We show that it can be employed for direct laser writing of image data or recording the polarization structure of optical vector beams. Scanning electron micrographs reveal a careful sculpting of the radius of curvature and height of the triangles composing the illuminated nanoantennas, as a result of plasmonic heating, that permits spatial tunability of the resonance response of the nanoantennas without sacrificing their geometric integrity. In contrast to other memory-dedicated approaches using Au nanorods embedded in a matrix medium, plasmonic film can be used in multiple application domains. To demonstrate this functionality, we utilize the structures as plasmonic optical tweezers and show sequestering of SiO2 microparticles into optically written channels formed between exposed sections of the film. The plasmonic film offers interesting possibilities for photonic applications including optofluidic channels "without walls," in situ tailorable biochemical sensing assays, and near-field particle manipulation and sorting.

  14. Laser cooling at low intensity in a strong magnetic field

    NASA Astrophysics Data System (ADS)

    van der Straten, P.; Shang, S.-Q.; Sheehy, B.; Metcalf, H.; Nienhuis, G.

    1993-05-01

    We have studied theoretically and experimentally the effect of a relatively strong magnetic field on sub-Doppler laser cooling in a one-dimensional optical molasses. We used the operator description of laser cooling with the Larmor precession frequency ωZ being much higher than the optical pumping rate. We found velocity-selective resonances (VSR) in the force at velocities vr=nωZ, with n=0,+/-1,+/-2 for both the scattering and redistribution force operators. These depend on the relative direction of the magnetic field and the polarization vectors of the light beams. Analytical results for the force on the atom are obtained in two cases that illustrate the effect of the VSR on the force. These formulas are compared with numerical calculations of the force. We also discovered a redistribution mechanism that relies on the gradient of the eigenstates of the light-shift operator, with eigenvalues that are independent of position so that a ``Sisyphus cooling'' picture does not apply. The theory is compared with many experimental results and excellent agreement is found. We believe that all essential features of laser cooling at low intensity are well described by this operator theory.

  15. Infra-red radiant intensity exposure safety study for the Eye Tracker.

    PubMed

    Pruehsner, William R; Enderle, John D

    2005-01-01

    With any device that is used to record or evaluate biosignals, it is in the inventor's interest to determine how that device withstands a rigorous examination in regards to its inherent safety during use. For this, a Risk Management (Hazard) Analysis is a useful exercise. With this in mind, the most probable hazard concerning the Eye Tracker System (a device used to measure saccadic eye movements utilizing Reflective Differencing of Infra-Red light) is the exposure effect to the human eye caused by the Radiant Intensity of the IR emitters mounted on the Head Mounted Transducer. Presented in this article are the results of a study used to determine the Radiant Intensity exposure of the Eye Tracker as designed. Comparing these results with accepted norms for Radiant Intensity exposure, a redesign of the Head Mounted Transducer is detailed with results given showing that this new transducer fits safely into the accepted norms of Radiant Intensity exposure. Presented are the mathematical calculations used for the initial study and the redesign.

  16. Intensity of the Geomagnetic Field During Precambrian Time

    NASA Astrophysics Data System (ADS)

    Dunlop, D. J.

    2011-12-01

    Interest in Precambrian paleomagnetic field intensity was sparked by C. J. Hale's proposal in a 1987 Nature paper that the Earth's dipole moment had increased very substantially around the Archean-Proterozoic boundary, perhaps signaling nucleation or growth of the inner core at that time. Theoretical estimates of the time of inner core formation vary quite widely and any firm observational constraint would be valuable. Growth of the inner core is believed to be essential in maintaining convection and driving the geodynamo. Subsequent paleointensity studies do not rule out Hale's hypothesis but they do not support it very strongly either. Hale's strong dipole moments of ~6 and 18 × 1022 Am2 from the 2465 Ma Matachewan and 2150 Ma Biscotasing dikes (Ontario, Canada) are contradicted by much lower values, 2.8 and 0.8 × 1022 Am2, respectively, in a 2003 study by Macouin et al. On the other hand, all the other Ontario dike swarms studied by Macouin et al. gave similarly low paleointensities, whereas high values of 6-8 × 1022 Am2 are reported at the close of the Archean in three studies by different authors: the 2700 Ma Stillwater complex and 2630 Ma Yellowknife 8a dikes (North America) and the 2450 Ma Burakova complex (Russia). However, recent studies by Tarduno et al. of earlier Archean (3450 and 3200 Ma) igneous rocks from the Kaapvaal craton (S. Africa) yield field intensities 50-70% as strong as modern-day values. The magnetic inclusions in silicate crystals from which these data come bear a demonstrably primary TRM, leaving no doubt that a vigorous geodynamo was in existence long before the close of the Archean. We are left with three working models: (1) Macouin et al.'s proposal that the geodynamo was only weakly operational throughout both the Archean and Proterozoic and only became truly vigorous in the Phanerozoic, the final 10% of Earth history. (2) Hale's proposal that the Archean-Proterozoic boundary marks the onset of "modern" geodynamo action, or at

  17. Amyotrophic lateral sclerosis and occupational exposure to electromagnetic fields

    SciTech Connect

    Davanipour, Z.; Sobel, E.; Bowman, J.D.; Qian, Z.; Will, A.D.

    1997-03-01

    In an hypothesis-generating case-control study of amyotrophic lateral sclerosis, lifetime occupational histories were obtained. The patients (n = 28) were clinic based. The occupational exposure of interest in this report is electromagnetic fields (EMFs). This is the first and so far the only exposure analyzed in this study. Occupational exposure up to 2 years prior to estimated disease symptom onset was used for construction of exposure indices for cases. Controls (n = 32) were blood and nonblood relatives of cases. Occupational exposure for controls was through the same age as exposure for the corresponding cases. Twenty (71%) cases and 28 (88%) controls had at least 20 years of work experience covering the exposure period. The occupational history and task data were used to classify blindly each occupation for each subject as having high, medium/high, medium, medium/low, or low EMF exposure, based primarily on data from an earlier and unrelated study designed to obtain occupational EMF exposure information on workers in ``electrical`` and ``nonelectrical`` jobs. By using the length of time each subject spent in each occupation through the exposure period, two indices of exposure were constructed: total occupational exposure (E{sub 1}) and average occupational exposure (E{sub 2}). For cases and controls with at least 20 years of work experience, the odds ratio (OR) for exposure at the 75th percentile of the E{sub 1} case exposure data relative to minimum exposure was 7.5 (P < 0.02; 95% CI, 1.4--38.1) and the corresponding OR for E{sub 2} was 5.5 (P < 0.02; 95% CI, 1.3--22.5). For all cases and controls, the ORs were 2.5 (P < 0.1; 95% CI, 0.9--8.1) for E{sub 1} and 2.3 (P = 0.12; 95% CI, 0.8--6.6) for E{sub 2}. This study should be considered an hypothesis-generating study. Larger studies, using incident cases and improved exposure assessment, should be undertaken.

  18. Echolocation behavior in big brown bats is not impaired after intense broadband noise exposures.

    PubMed

    Hom, Kelsey N; Linnenschmidt, Meike; Simmons, James A; Simmons, Andrea Megela

    2016-10-15

    Echolocating bats emit trains of intense ultrasonic biosonar pulses and listen to weaker echoes returning from objects in their environment. Identification and categorization of echoes are crucial for orientation and prey capture. Bats are social animals and often fly in groups in which they are exposed to their own emissions and to those from other bats, as well as to echoes from multiple surrounding objects. Sound pressure levels in these noisy conditions can exceed 110 dB, with no obvious deleterious effects on echolocation performance. Psychophysical experiments show that big brown bats (Eptesicus fuscus) do not experience temporary threshold shifts after exposure to intense broadband ultrasonic noise, but it is not known if they make fine-scale adjustments in their pulse emissions to compensate for any effects of the noise. We investigated whether big brown bats adapt the number, temporal patterning or relative amplitude of their emitted pulses while flying through an acoustically cluttered corridor after exposure to intense broadband noise (frequency range 10-100 kHz; sound exposure level 152 dB). Under these conditions, four bats made no significant changes in navigation errors or in pulse number, timing and amplitude 20 min, 24 h or 48 h after noise exposure. These data suggest that big brown bats remain able to perform difficult echolocation tasks after exposure to ecologically realistic levels of broadband noise.

  19. Evidence for the initiation of decompression sickness by exposure to intense underwater sound.

    PubMed

    Tal, Dror; Shachar-Bener, Hofit; Hershkovitz, Dov; Arieli, Yehuda; Shupak, Avi

    2015-09-01

    Mass stranding of cetaceans (whales and dolphins), in close association with the activity of naval sonar systems, has been reported on numerous occasions. Necropsy showed bubble-associated lesions similar to those described in human decompression sickness (DCS). We examined the hypothesis that exposure to underwater sound may potentiate DCS. Rats were subjected to immersion and simulated dives with and without simultaneous acoustic transmissions at pressure levels and frequencies of 204 dB/8 kHz and 183.3 dB/15 kHz. DCS severity was assessed using the rotating wheel method. Recording of somatosensory evoked potentials (SSEPs) was employed under general anesthesia as an electrophysiological measure of neurologic insult. A significantly higher rate of decompression sickness was found among animals exposed to the 204-dB/8-kHz sound field. Significantly higher pathological SSEPs scores were noted for both underwater sound protocols. Pathological SSEPs scores in animals immersed during the acoustic transmissions, but without changes in ambient pressure, were comparable to those observed in animals exposed to the dive profile. The results demonstrate induction of neurological damage by intense underwater sound during immersion, with a further deleterious effect when this was combined with decompression stress. The study outcome has potential implications for human diving safety and may provide an explanation for the mass stranding of cetaceans purportedly associated with sonar activity. Copyright © 2015 the American Physiological Society.

  20. Evidence for the initiation of decompression sickness by exposure to intense underwater sound

    PubMed Central

    Tal, Dror; Shachar-Bener, Hofit; Hershkovitz, Dov; Arieli, Yehuda

    2015-01-01

    Mass stranding of cetaceans (whales and dolphins), in close association with the activity of naval sonar systems, has been reported on numerous occasions. Necropsy showed bubble-associated lesions similar to those described in human decompression sickness (DCS). We examined the hypothesis that exposure to underwater sound may potentiate DCS. Rats were subjected to immersion and simulated dives with and without simultaneous acoustic transmissions at pressure levels and frequencies of 204 dB/8 kHz and 183.3 dB/15 kHz. DCS severity was assessed using the rotating wheel method. Recording of somatosensory evoked potentials (SSEPs) was employed under general anesthesia as an electrophysiological measure of neurologic insult. A significantly higher rate of decompression sickness was found among animals exposed to the 204-dB/8-kHz sound field. Significantly higher pathological SSEPs scores were noted for both underwater sound protocols. Pathological SSEPs scores in animals immersed during the acoustic transmissions, but without changes in ambient pressure, were comparable to those observed in animals exposed to the dive profile. The results demonstrate induction of neurological damage by intense underwater sound during immersion, with a further deleterious effect when this was combined with decompression stress. The study outcome has potential implications for human diving safety and may provide an explanation for the mass stranding of cetaceans purportedly associated with sonar activity. PMID:26133802

  1. Static fields: biological effects and mechanisms relevant to exposure limits.

    PubMed

    van Rongen, Eric; Saunders, Richard D; van Deventer, Emilie T; Repacholi, Michael H

    2007-06-01

    Recently, the International EMF Project of the World Health Organization (WHO) published an Environmental Health Criteria monograph on static electric and magnetic fields. In the present paper a short overview is given of the biological and health effects discussed in this document. The main conclusions are that no acute effects other than transient phenomena such as vertigo and nausea have been observed with exposure to static magnetic flux densities up to 8 T. There are no reports of long term or chronic adverse effects following prolonged static magnetic field exposure, but few data are available on which to base any judgment. The guidelines on static field exposure recommended by ICNIRP in 1994 are discussed in the light of current scientific knowledge.

  2. Modelling and design of extremely low frequency uniform magnetic field exposure apparatus for in vivo bioelectromagnetic studies.

    PubMed

    Cvetkovic, D; Cosic, I

    2007-01-01

    Helmholtz coils are regularly utilised for various extremely low frequency (ELF) bioelectromagnetic experiments. The evaluation was conducted for the Helmholtz coil magnetic field frequency and uniformity, characterised by frequency-domain and geometric ELF magnetic exposure characteristics. An established approach which consisted of the mathematical calculations of the geometric parameters, computational modeling, and experimental development measurements of the Helmholtz coil's magnetic field frequency and uniformity, improved the quality of magnetic field uniformity and minimised the magnetic field intensity losses.

  3. Slope stability improvement using low intensity field electrosmosis

    NASA Astrophysics Data System (ADS)

    Armillotta, Pasquale

    2014-05-01

    The electrosmosis technique has been introduced in the past for slope stabilization. However, its application to real cases has been scarce due to several drawbacks mostly related to the high intensity electric field needed (1.0 V/cm or higher): the rapid degradation of the electrodes, the high system management cost, the heating and cracking of the soil and the reduction of its colloidal fraction. Thanks to the introduction of new materials, the technique is currently applied to decrease the consolidation time of saturated clay soils (forcing the elimination of water), consequently improving its mechanical strength. In clay soils, the volume variation is influenced by the presence of smectites. The clay compressibility decreases with the increasing of electrolytes concentration. Soil containing smectites that have interacted with calcium showed a reduction or the absence of swelling during hydration with distilled water and a positive increase of their shear strength. The different values of pH between the anode (acid) and the cathode (basic), induced by the electrosmosis create the conditions for the precipitation of CaCO3 near the cathode. The injection of solutions containing calcium in soils and their diffusion induced by the electrosmosis, lead to calcium precipitation and consequential increase of the shear strength. The material technological advances and the laboratory experiences described in this paper, demonstrate that the use low electric field (0.1 V/cm or lower) intensity electrosmosis (LEFE in acronym) can be effective for soil dewatering and shear strength increase while reducing its adverse effect. The LEFE can be used to: reduce the potential for swelling of active clay minerals through the introduction of ions and the precipitation of hardening substances; induce the "dewatering" in cohesive soils. Several Lab activities were carried out, using custom made electrosmosis equipment. These activities can be divided in two phases: Phase 1

  4. Early exposure of rotating magnetic fields promotes central nervous regeneration in planarian Girardia sinensis.

    PubMed

    Chen, Qiang; Lin, Gui-miao; Wu, Nan; Tang, Sheng-wei; Zheng, Zhi-jia; Lin, Marie Chia-mi; Xu, Gai-xia; Liu, Hao; Deng, Yue-yue; Zhang, Xiao-yun; Chen, Si-ping; Wang, Xiao-mei; Niu, Han-ben

    2016-05-01

    Magnetic field exposure is an accepted safe and effective modality for nerve injury. However, it is clinically used only as a supplement or salvage therapy at the later stage of treatment. Here, we used a planarian Girardia sinensis decapitated model to investigate beneficial effects of early rotary non-uniform magnetic fields (RMFs) exposure on central nervous regeneration. Our results clearly indicated that magnetic stimulation induced from early RMFs exposure significantly promoted neural regeneration of planarians. This stimulating effect is frequency and intensity dependent. Optimum effects were obtained when decapitated planarians were cultured at 20 °C, starved for 3 days before head-cutting, and treated with 6 Hz 0.02 T RMFs. At early regeneration stage, RMFs exposure eliminated edema around the wound and facilitated subsequent formation of blastema. It also accelerated cell proliferation and recovery of neuron functionality. Early RMFs exposure up-regulated expression of neural regeneration related proteins, EGR4 and Netrin 2, and mature nerve cell marker proteins, NSE and NPY. These results suggest that RMFs therapy produced early and significant benefit in central nervous regeneration, and should be clinically used at the early stage of neural regeneration, with appropriate optimal frequency and intensity. © 2016 Wiley Periodicals, Inc.

  5. The determinants of Canadian children's personal exposures to magnetic fields.

    PubMed

    Armstrong, B G; Deadman, J; McBride, M L

    2001-04-01

    Study of the health effects of magnetic fields often depends on identifying determinants and hence indicators of personal exposure. This study identified determinants of children's exposure to magnetic fields and constructed a prediction model for them. For 632 children participating in a case-control study of childhood leukemia, we made direct measures of exposure over 48 h using a portable device, together with observations on candidate determinants. A child's age and sex, the proportion of time spent in the home, and their parents' education or income were very weak predictors of (logged) mean 48 h magnetic field (R(2) < 1%). More important were province (R(2) = 8.0%) and type of residence (R(2) = 11.3%). Low temperatures at the time of measurement were associated with high fields (about 20% increase for each 10 degrees C below 14, R(2) = 4.9%). Several visible attributes of wiring around residences predicted exposure, mostly captured in the Wertheimer-Leeper wire code (R(2) = 13.5%). Stationary 24 h measurement in the bedroom (R(2) = 63.3%) and spot measurements outside the house (R(2) = 40.7%) predicted personal exposures best. Adding other minor predictors increased only slightly variance explained by 24 h stationary (R(2) = 66.2%) and spot (R(2) = 46.8%) measurements. Without spot or stationary measurements, the best model was much less powerful (R(2) = 29.0%). We conclude that spot measurements outside the residence provide a moderately effective basis for estimating exposure for children living there, but do not perform as well as 24 h stationary measurements in the child's bedroom. Although several other easily-observed variables were associated with personal exposure, they were weak determinants, either individually or in combination.

  6. Residential magnetic fields predicted from wiring configurations: I. Exposure model.

    PubMed

    Bowman, J D; Thomas, D C; Jiang, L; Jiang, F; Peters, J M

    1999-10-01

    A physically based model for residential magnetic fields from electric transmission and distribution wiring was developed to reanalyze the Los Angeles study of childhood leukemia by London et al. For this exposure model, magnetic field measurements were fitted to a function of wire configuration attributes that was derived from a multipole expansion of the Law of Biot and Savart. The model parameters were determined by nonlinear regression techniques, using wiring data, distances, and the geometric mean of the ELF magnetic field magnitude from 24-h bedroom measurements taken at 288 homes during the epidemiologic study. The best fit to the measurement data was obtained with separate models for the two major utilities serving Los Angeles County. This model's predictions produced a correlation of 0.40 with the measured fields, an improvement on the 0.27 correlation obtained with the Wertheimer-Leeper (WL) wire code. For the leukemia risk analysis in a companion paper, the regression model predicts exposures to the 24-h geometric mean of the ELF magnetic fields in Los Angeles homes where only wiring data and distances have been obtained. Since these input parameters for the exposure model usually do not change for many years, the predicted magnetic fields will be stable over long time periods, just like the WL code. If the geometric mean is not the exposure metric associated with cancer, this regression technique could be used to estimate long-term exposures to temporal variability metrics and other characteristics of the ELF magnetic field which may be cancer risk factors.

  7. Mercury's Magnetosphere during Intervals of Intense Southward Interplanetary Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Slavin, J. A.; Jia, X.; Raines, J. M.; Jasinski, J. M.; Poh, G.; Dewey, R. M.; DiBraccio, G. A.; Gershman, D. J.; Imber, S.

    2016-12-01

    MESSENGER's observations of Mercury's magnetosphere by have shown it to be highly dynamic, especially in response to coronal mass ejections. Previous investigations have focused upon the compression of the magnetosphere by high solar wind pressures and the role of induction currents generated in Mercury's interior. Here the response of this magnetosphere to strong southward interplanetary magnetic fields (IMF) is examined for a range in solar wind conditions. Having the same intrinsic magnetic dipole polarity as the Earth, the magnetic shear angle across the forward magnetopause maximizes for southward IMF. While the results confirm that Mercury's magnetosphere does not exhibit the simple "half-wave rectifier" (i.e. significant magnetopause reconnection only for large magnetic shear angles) response observed at Earth, it is found that southward IMF produces extreme erosion of the dayside magnetosphere and intense reconnection-driven dynamics in the magnetotail. The results are used to produce a more complete picture of how Mercury's magnetosphere responds to extreme conditions in the inner heliosphere.

  8. Zero-width resonances in intense-field molecular photodissociation

    SciTech Connect

    Atabek, Osman; Lefebvre, Roland; Gadea, Florent Xavier

    2006-12-15

    We provide additional evidence for the existence of zero-width resonances in the intense-field photodissociation of H{sub 2}{sup +}. In a previous investigation [Atabek, Chrysos, and Lefebvre, Phys. Rev. A 49, R8 (1994)] the situation, in a two-channel dressed picture, corresponded to a diabatic crossing point classically reachable in both adiabatic potentials. A semiclassical explanation could be modeled after that developed for predissociation in the intermediate-coupling regime. At higher frequencies the crossing point lies between the two turning points. A numerical study shows that zero-width resonances exist also in such a case. An extension of the semiclassical approach provides an explanation for the occurrence of these resonances. It is shown that they survive even when going to a multichannel description. The associated wave functions and probability densities are studied: they are very similar to those of the upper adiabatic potential, with a minor component in the lower adiabatic channel. Some conditions for the production of such long-lived dressed molecular species are stated.

  9. Fragmentation dynamics of Ar2^+ dimers in intense laser fields

    NASA Astrophysics Data System (ADS)

    Magrakvelidze, M.; Wu, J.; Dörner, R.; Thumm, U.

    2012-06-01

    We studied the fragmentation dynamics of the Ar2 dimers in 790 nm pump and 1400 nm probe pulses with intensities of 10^14 W/cm^2 by analyzing kinetic energy release (KER) spectra as a function of the pump probe delay. The KER spectra are measured by detecting Ar-ion fragments in a COLTRIMS [1] setup and are compared with model calculations based on the numerical propagations of the time-dependent Schr"odinger equation [2]. The measured spectra are best reproduced by two-state calculations that include the adiabatic electronic states I(1/2)u and II(1/2)g of Ar2^+, dipole coupled in the pump- and probe-laser electric fields. [4pt] [1] J. Wu, A. Vredenborg, B. Ulrich, L. Ph. H. Schmidt, M. Meckel, S. Voss, H. Sann, H. Kim, T. Jahnke, and R. D"orner, PRA 83, 061403(R) (2011) [0pt] [2] M. Magrakvelidze, F. He, Th. Niederhausen, I. V. Litvinyuk, and U. Thumm, PRA 79, 033410 (2009).

  10. Effect of preadmission sunlight exposure on intensive care unit-acquired delirium: a multicenter study.

    PubMed

    Simons, Koen S; Workum, Jessica D; Slooter, Arjen J C; van den Boogaard, Mark; van der Hoeven, Johannes G; Pickkers, Peter

    2014-04-01

    It is assumed that there is a relation between light exposure and delirium incidence. The aim of our study was to determine the effect of prehospital light exposure on the incidence of intensive care unit (ICU)-acquired delirium. Data from 3 ICUs in the Netherlands were analyzed retrospectively. Delirium was assessed with the Confusion Assessment Method for the ICU. Daily light intensity data were obtained from meteorological stations in the vicinity of the 3 hospitals. The association between light intensity and delirium incidence was analyzed using logistic regression analysis adjusting for known covariates for delirium. Data of 3198 patients, aged (mean ± SD) 61.9 ± 15.3 years with Acute Physiology and Chronic Health Evaluation II score 16.4 ± 6.6 were analyzed. Delirium incidence was 31.2% and did not vary significantly throughout the year. Twenty-eight-day preadmission photoperiod was highest in spring and lowest in winter; however, no association between light exposure and delirium incidence was found (odds ratio, 1.00; 95% confidence interval, 0.99-1.00; P = 0.72). Furthermore, delirium was significantly associated with age, infection, use of sedatives, Acute Physiology and Chronic Health Evaluation II score, and diagnosis of neurological disease or trauma. The incidence of delirium does not differ per season and prior sunlight exposure does not play a role of importance in the development of ICU-acquired delirium. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Malnutrition and overcrowding/intensive exposure in severe measles infection: review of community studies.

    PubMed

    Aaby, P

    1988-01-01

    Most hospital studies of measles mortality suggest that high case fatality ratios are associated with malnutrition. However, no community study has documented this association. On the contrary, several community studies from Africa and Asia have found no relation between nutritional status and risk of severe or fatal measles. Instead, overcrowding and intensive exposure may be more important determinants of measles mortality. Clustering of several cases in the family and/or intensive exposure were associated with high measles mortality in community studies in West Africa, Bangladesh, and England. Thus sociocultural factors that concentrate many susceptible children in the home may increase the case-fatality ratio in measles. Conversely, this ratio will be lower when measles cases are dispersed. Siblings in rural areas, where long intervals separate epidemics, run a higher risk of contracting measles simultaneously than do their urban counterparts. Measles vaccination increases herd immunity and diminishes the clustering of several cases in a family. Vaccination may therefore reduce mortality even among unvaccinated children who contract measles. Crowding and intensive exposure may partly explain regional and historical variations in measles mortality; community studies suggest that mortality is high when a high proportion of measles patients have secondary cases (acquired through exposure at home).

  12. Low intensity and frequency pulsed electromagnetic fields selectively impair breast cancer cell viability.

    PubMed

    Crocetti, Sara; Beyer, Christian; Schade, Grit; Egli, Marcel; Fröhlich, Jürg; Franco-Obregón, Alfredo

    2013-01-01

    A common drawback of many anticancer therapies is non-specificity in action of killing. We investigated the potential of ultra-low intensity and frequency pulsed electromagnetic fields (PEMFs) to kill breast cancer cells. Our criteria to accept this technology as a potentially valid therapeutic approach were: 1) cytotoxicity to breast cancer cells and; 2) that the designed fields proved innocuous to healthy cell classes that would be exposed to the PEMFs during clinical treatment. MCF7 breast cancer cells and their normal counterparts, MCF10 cells, were exposed to PEMFs and cytotoxic indices measured in order to design PEMF paradigms that best kill breast cancer cells. The PEMF parameters tested were: 1) frequencies ranging from 20 to 50 Hz; 2) intensities ranging from 2 mT to 5 mT and; 3) exposure durations ranging from 30 to 90 minutes per day for up to three days to determine the optimum parameters for selective cancer cell killing. We observed a discrete window of vulnerability of MCF7 cells to PEMFs of 20 Hz frequency, 3 mT magnitude and exposure duration of 60 minutes per day. The cell damage accrued in response to PEMFs increased with time and gained significance after three days of consecutive daily exposure. By contrast, the PEMFs parameters determined to be most cytotoxic to breast cancer MCF-7 cells were not damaging to normal MCF-10 cells. Based on our data it appears that PEMF-based anticancer strategies may represent a new therapeutic approach to treat breast cancer without affecting normal tissues in a manner that is non-invasive and can be potentially combined with existing anti-cancer treatments.

  13. Low Intensity and Frequency Pulsed Electromagnetic Fields Selectively Impair Breast Cancer Cell Viability

    PubMed Central

    Crocetti, Sara; Beyer, Christian; Schade, Grit; Egli, Marcel; Fröhlich, Jürg; Franco-Obregón, Alfredo

    2013-01-01

    Introduction A common drawback of many anticancer therapies is non-specificity in action of killing. We investigated the potential of ultra-low intensity and frequency pulsed electromagnetic fields (PEMFs) to kill breast cancer cells. Our criteria to accept this technology as a potentially valid therapeutic approach were: 1) cytotoxicity to breast cancer cells and; 2) that the designed fields proved innocuous to healthy cell classes that would be exposed to the PEMFs during clinical treatment. Methods MCF7 breast cancer cells and their normal counterparts, MCF10 cells, were exposed to PEMFs and cytotoxic indices measured in order to design PEMF paradigms that best kill breast cancer cells. The PEMF parameters tested were: 1) frequencies ranging from 20 to 50 Hz; 2) intensities ranging from 2 mT to 5 mT and; 3) exposure durations ranging from 30 to 90 minutes per day for up to three days to determine the optimum parameters for selective cancer cell killing. Results We observed a discrete window of vulnerability of MCF7 cells to PEMFs of 20 Hz frequency, 3 mT magnitude and exposure duration of 60 minutes per day. The cell damage accrued in response to PEMFs increased with time and gained significance after three days of consecutive daily exposure. By contrast, the PEMFs parameters determined to be most cytotoxic to breast cancer MCF-7 cells were not damaging to normal MCF-10 cells. Conclusion Based on our data it appears that PEMF-based anticancer strategies may represent a new therapeutic approach to treat breast cancer without affecting normal tissues in a manner that is non-invasive and can be potentially combined with existing anti-cancer treatments. PMID:24039828

  14. Validating a model for detecting magnetic field intensity using dynamic neural fields.

    PubMed

    Taylor, Brian K

    2016-11-07

    Several animals use properties of Earth's magnetic field as a part of their navigation toolkit to accomplish tasks ranging from local homing to continental migration. Studying these behaviors has led to the postulation of both a magnetite-based sense, and a chemically based radical-pair mechanism. Several researchers have proposed models aimed at both understanding these mechanisms, and offering insights into future physiological experiments. The present work mathematically implements a previously developed conceptual model for sensing and processing magnetite-based magnetosensory feedback by using dynamic neural fields, a computational neuroscience tool for modeling nervous system dynamics and processing. Results demonstrate the plausibility of the conceptual model's predictions. Specifically, a population of magnetoreceptors in which each individual can only sense directional information can encode magnetic intensity en masse. Multiple populations can encode both magnetic direction, and intensity, two parameters that several animals use in their navigational toolkits. This work can be expanded to test other magnetoreceptor models. Published by Elsevier Ltd.

  15. Neonatal lead exposure impairs development of rodent barrel field cortex

    PubMed Central

    Wilson, Mary Ann; Johnston, Michael V.; Goldstein, Gary W.; Blue, Mary E.

    2000-01-01

    Childhood exposure to low-level lead can permanently reduce intelligence, but the neurobiologic mechanism for this effect is unknown. We examined the impact of lead exposure on the development of cortical columns, using the rodent barrel field as a model. In all areas of mammalian neocortex, cortical columns constitute a fundamental structural unit subserving information processing. Barrel field cortex contains columnar processing units with distinct clusters of layer IV neurons that receive sensory input from individual whiskers. In this study, rat pups were exposed to 0, 0.2, 1, 1.5, or 2 g/liter lead acetate in their dam's drinking water from birth through postnatal day 10. This treatment, which coincides with the development of segregated columns in the barrel field, produced blood lead concentrations from 1 to 31 μg/dl. On postnatal day 10, the area of the barrel field and of individual barrels was measured. A dose-related reduction in barrel field area was observed (Pearson correlation = −0.740; P < 0.001); mean barrel field area in the highest exposure group was decreased 12% versus controls. Individual barrels in the physiologically more active caudoventral group were affected preferentially. Total cortical area measured in the same sections was not altered significantly by lead exposure. These data support the hypothesis that lead exposure may impair the development of columnar processing units in immature neocortex. We demonstrate that low levels of blood lead, in the range seen in many impoverished inner-city children, cause structural alterations in a neocortical somatosensory map. PMID:10805810

  16. Behavioral evidence for possible simultaneous induction of hyperacusis and tinnitus following intense sound exposure.

    PubMed

    Chen, G; Lee, C; Sandridge, S A; Butler, H M; Manzoor, N F; Kaltenbach, J A

    2013-06-01

    Many human subjects suffering from chronic tinnitus also suffer from hyperacusis, a heightened perception of loudness at moderate to intense sound levels. While numerous studies suggest that animals develop chronic tinnitus following intense noise exposure, it is not yet clear whether sound exposure also induces chronic hyperacusis-like responses in animals. We addressed this question by examining the chronic effects of intense sound exposure on the acoustic startle response (ASR) and its suppression by background noise containing brief gaps. We compared startle amplitudes in intense tone-exposed (10 kHz, 115 dB SPL, 4 h) and age-matched controls at 2-28 weeks post-exposure. While both groups showed similar startle thresholds, exposed animals showed a hyperacusis-like augmentation of ASR at high stimulus levels. Addition of background noise had little effect on ASR in controls but had a strong suppressive effect on startle in exposed animals, indicating a sensitization to background noise. When the background noise contained a gap preceding the startle stimulus, ASR was suppressed in control animals, but exposed animals showed a marked weakening of gap-induced suppression of ASR. This weakening of gap-induced startle suppression is consistent with the interpretation that the gap may have been masked by tinnitus. The associated hyper-responsiveness to startle stimuli presented alone and the sensitization to background noise suggest that hyperacusis may have also been induced. The results indicate that noise exposure leads to increases in the gain of auditory responsiveness and may offer a model of the association of hyperacusis with tinnitus.

  17. Potential adverse effects of high-intensity focused ultrasound exposure on blood vessels in vivo.

    PubMed

    Hynynen, K; Chung, A H; Colucci, V; Jolesz, F A

    1996-01-01

    The aim of the study was to evaluate the potential adverse effects of high intensity ultrasound exposure on blood vessels during noninvasive focused ultrasound surgery. A hydraulic MR-compatible positioning device was used to manipulate a focused ultrasound transducer (frequency 1.49 MHz, f-number = 0.8) in an MRI scanner. The system was used to sonicate a branch of the femoral artery and vein of 19 rabbits (26 thighs) in vivo at intensity levels above the threshold for transient cavitation; i.e., between 4400 and 8800 W cm-2 with multiple 1 s pulses stepped across the vessels (step size = 0.7 mm). The vessels were located and followed by MR angiography. In 13 rabbits, x-ray angiograms were also performed after the animals were euthanized. The results demonstrated that the 1 s high-intensity exposures caused the arteries to constrict at all exposure levels tested. At the intensity of 5800 W cm-2 and above, the MRI angiogram immediately after the sonications showed no flow. The x-ray angiograms (1-2 h later) showed that the blood vessels were open, but constricted to about 50% or less of their diameter. Both the MR and x-ray angiograms showed that the vessel diameters relaxed toward their initial diameter during the first week after sonication. In five cases, hemorrhage or vessel rupture was caused by the sonication. This study demonstrates that short, high-intensity focused ultrasound exposure can cause vessel spasm and hemorrhage when transient cavitation is present. This condition should be avoided during noninvasive focused ultrasound surgery.

  18. Cationic peptide exposure enhances pulsed-electric-field-mediated membrane disruption.

    PubMed

    Kennedy, Stephen M; Aiken, Erik J; Beres, Kaytlyn A; Hahn, Adam R; Kamin, Samantha J; Hagness, Susan C; Booske, John H; Murphy, William L

    2014-01-01

    The use of pulsed electric fields (PEFs) to irreversibly electroporate cells is a promising approach for destroying undesirable cells. This approach may gain enhanced applicability if the intensity of the PEF required to electrically disrupt cell membranes can be reduced via exposure to a molecular deliverable. This will be particularly impactful if that reduced PEF minimally influences cells that are not exposed to the deliverable. We hypothesized that the introduction of charged molecules to the cell surfaces would create regions of enhanced transmembrane electric potential in the vicinity of each charged molecule, thereby lowering the PEF intensity required to disrupt the plasma membranes. This study will therefore examine if exposure to cationic peptides can enhance a PEF's ability to disrupt plasma membranes. We exposed leukemia cells to 40 μs PEFs in media containing varying concentrations of a cationic peptide, polyarginine. We observed the internalization of a membrane integrity indicator, propidium iodide (PI), in real time. Based on an individual cell's PI fluorescence versus time signature, we were able to determine the relative degree of membrane disruption. When using 1-2 kV/cm, exposure to >50 μg/ml of polyarginine resulted in immediate and high levels of PI uptake, indicating severe membrane disruption, whereas in the absence of peptide, cells predominantly exhibited signatures indicative of no membrane disruption. Additionally, PI entered cells through the anode-facing membrane when exposed to cationic peptide, which was theoretically expected. Exposure to cationic peptides reduced the PEF intensity required to induce rapid and irreversible membrane disruption. Critically, peptide exposure reduced the PEF intensities required to elicit irreversible membrane disruption at normally sub-electroporation intensities. We believe that these cationic peptides, when coupled with current advancements in cell targeting techniques will be useful tools in

  19. Cationic Peptide Exposure Enhances Pulsed-Electric-Field-Mediated Membrane Disruption

    PubMed Central

    Kennedy, Stephen M.; Aiken, Erik J.; Beres, Kaytlyn A.; Hahn, Adam R.; Kamin, Samantha J.; Hagness, Susan C.; Booske, John H.; Murphy, William L.

    2014-01-01

    Background The use of pulsed electric fields (PEFs) to irreversibly electroporate cells is a promising approach for destroying undesirable cells. This approach may gain enhanced applicability if the intensity of the PEF required to electrically disrupt cell membranes can be reduced via exposure to a molecular deliverable. This will be particularly impactful if that reduced PEF minimally influences cells that are not exposed to the deliverable. We hypothesized that the introduction of charged molecules to the cell surfaces would create regions of enhanced transmembrane electric potential in the vicinity of each charged molecule, thereby lowering the PEF intensity required to disrupt the plasma membranes. This study will therefore examine if exposure to cationic peptides can enhance a PEF’s ability to disrupt plasma membranes. Methodology/Principal Findings We exposed leukemia cells to 40 μs PEFs in media containing varying concentrations of a cationic peptide, polyarginine. We observed the internalization of a membrane integrity indicator, propidium iodide (PI), in real time. Based on an individual cell’s PI fluorescence versus time signature, we were able to determine the relative degree of membrane disruption. When using 1–2 kV/cm, exposure to >50 μg/ml of polyarginine resulted in immediate and high levels of PI uptake, indicating severe membrane disruption, whereas in the absence of peptide, cells predominantly exhibited signatures indicative of no membrane disruption. Additionally, PI entered cells through the anode-facing membrane when exposed to cationic peptide, which was theoretically expected. Conclusions/Significance Exposure to cationic peptides reduced the PEF intensity required to induce rapid and irreversible membrane disruption. Critically, peptide exposure reduced the PEF intensities required to elicit irreversible membrane disruption at normally sub-electroporation intensities. We believe that these cationic peptides, when coupled with

  20. 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...

  1. 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...

  2. Does hyperbaric oxygen exposure affect high-intensity, short-duration exercise performance?

    PubMed

    Rozenek, Ralph; Fobel, Brennan F; Banks, Jerry C; Russo, Albert C; Lacourse, Michael G; Strauss, Michael B

    2007-11-01

    Hyperbaric oxygen (HBO) exposure involves the breathing of 100% oxygen under conditions of elevated atmospheric pressure and is used to increase the oxygen content of the plasma fraction of arterial blood. The purpose of this study was to determine the effects of acute HBO exposure on selected physiological responses and performance in response to maximal lower extremity or upper extremity short-term, high-intensity exercise. The study was performed with 2 separate experiments incorporating double-blinded and randomized protocols. In experiment 1, 9 subjects ran on a treadmill at a speed of 268 m x min(-1) with a predetermined grade. In experiment 2, 9 different subjects performed a repetitive bench press exercise. Both exercise protocols were designed to induce fatigue within 1-2 minutes. Within each experiment, subjects received either a 1-hour HBO exposure inspiring 100% O2 at 202.6 kPa (2.0 atmospheres absolute pressure [ATA]) or a 1-hour sham exposure inspiring ambient air at 121.5 kPa (1.2 ATA) before exercise. No significant differences (p > or = 0.05) were observed in postexercise blood lactate concentrations, peak heart rate, ratings of perceived exertion, or performance as determined by treadmill running time or number of completed lifts. Unlike other methods that elevate oxygen content of the blood, acute HBO exposure appears to have no significant effect on subsequent high-intensity running or lifting performance.

  3. Electromagnetic field exposure assessment in Europe radiofrequency fields (10 MHz-6 GHz).

    PubMed

    Gajšek, Peter; Ravazzani, Paolo; Wiart, Joe; Grellier, James; Samaras, Theodoros; Thuróczy, György

    2015-01-01

    Average levels of exposure to radiofrequency (RF) electromagnetic fields (EMFs) of the general public in Europe are difficult to summarize, as exposure levels have been reported differently in those studies in which they have been measured, and a large proportion of reported measurements were very low, sometimes falling below detection limits of the equipment used. The goal of this paper is to present an overview of the scientific literature on RF EMF exposure in Europe and to characterize exposure within the European population. A comparative analysis of the results of spot or long-term RF EMF measurements in the EU indicated that mean electric field strengths were between 0.08 V/m and 1.8 V/m. The overwhelming majority of measured mean electric field strengths were <1 V/m. It is estimated that <1% were above 6 V/m and <0.1% were above 20 V/m. No exposure levels exceeding European Council recommendations were identified in these surveys. Most population exposures from signals of radio and television broadcast towers were observed to be weak because these transmitters are usually far away from exposed individuals and are spatially sparsely distributed. On the other hand, the contribution made to RF exposure from wireless telecommunications technology is continuously increasing and its contribution was above 60% of the total exposure. According to the European exposure assessment studies identified, three population exposure categories (intermittent variable partial body exposure, intermittent variable low-level whole-body (WB) exposure and continuous low-level WB exposure) were recognized by the authors as informative for possible future risk assessment.

  4. Exposure to oscillating magnetic fields influences sensitivity to electrical stimuli. 2: Experiments on humans

    SciTech Connect

    Papi, F.; Del Seppia, C.; Luschi, P.; Ghione, S.; Rosa, C.

    1995-12-01

    To assess the effect of a magnetic treatment on pain perception, the authors compared the sensory threshold in 18 healthy volunteers. They determined the threshold by noninvasive electrical stimulation of the tooth pulp and skin before and after exposure to an altered magnetic field of low intensity and to a sham treatment. Five different parameters were recorded: the sensory and pain thresholds for the tooth and the sensory, pain, and tolerance thresholds for the skin. Two hours of exposure to a weak, oscillating magnetic field induced a significant decrease in three parameters (dental sensory and cutaneous pain and tolerance thresholds), whereas the other two parameters showed a similar tendency. When the same subjects were exposed to a sham treatment, only marginal, nonsignificant variations in all parameters were observed. These results represent the first piece of evidence that weak alterations of the magnetic field may induce hyperalgesia in humans.

  5. Bioeffects of moderate-intensity static magnetic fields on cell cultures.

    PubMed

    Dini, Luciana; Abbro, Luigi

    2005-01-01

    The interaction of static magnetic fields (SMFs) with living organisms is a rapidly growing field of investigation. However, despite the increasing number of studies on the effects of the interaction of SMFs with living organisms, many gaps in our knowledge still remain. One reason why it is extremely important to deeply understand the true mode of action of MFs on living organisms, is the need to protect human health in consideration of the probable future introduction of new technologies such as magnetically levitated trains and the therapeutical use of MFs (e.g. magnetic resonance imaging, MRI, coupling of MF exposure with chemotherapy). The lack of knowledge of the morphological modifications brought about by exposure to moderate-intensity SMFs prompted us to investigate the bioeffects of 6mT SMFs on different cell types, by means of light and electron microscopy, confocal laser scanning microscopy and immuno- or cytochemistry. In the present article we report our own and other data from the literature on the morphological studies of the bioeffects of moderate-intensity SMFs. We focus on morphological modifications related to cell shape, cell surface, cytoskeleton, and plasma membrane expression of molecules and carbohydrate residues. The effects of exposure to moderate-intensity SMF for 24 or 48 h, on apoptosis, on apoptotic related gene products, on macrophagic differentiation and on phagocytosis of apoptotic cells in primary cell cultures (transformed or stabilized cell lines) will be also discussed. Moderate-intensity (6mT) SMFs induced modifications of cell shape, cell surface and cytoskeleton, progressively achieved during the entire period of exposure. In general, at the end of the exposure period, the cells had a less flat shape due to partial detachment from the culture dishes or a more round-elongated shape (in relation to adhesion growth or in suspension growth respectively) with many irregular lamellar microvilli, while the morphology of the

  6. Radiofrequency-electromagnetic field exposures in kindergarten children.

    PubMed

    Bhatt, Chhavi Raj; Redmayne, Mary; Billah, Baki; Abramson, Michael J; Benke, Geza

    2017-09-01

    The aim of this study was to assess environmental and personal radiofrequency-electromagnetic field (RF-EMF) exposures in kindergarten children. Ten children and 20 kindergartens in Melbourne, Australia participated in personal and environmental exposure measurements, respectively. Order statistics of RF-EMF exposures were computed for 16 frequency bands between 88 MHz and 5.8 GHz. Of the 16 bands, the three highest sources of environmental RF-EMF exposures were: Global System for Mobile Communications (GSM) 900 MHz downlink (82 mV/m); Universal Mobile Telecommunications System (UMTS) 2100MHz downlink (51 mV/m); and GSM 900 MHz uplink (45 mV/m). Similarly, the three highest personal exposure sources were: GSM 900 MHz downlink (50 mV/m); UMTS 2100 MHz downlink, GSM 900 MHz uplink and GSM 1800 MHz downlink (20 mV/m); and Frequency Modulation radio, Wi-Fi 2.4 GHz and Digital Video Broadcasting-Terrestrial (10 mV/m). The median environmental exposures were: 179 mV/m (total all bands), 123 mV/m (total mobile phone base station downlinks), 46 mV/m (total mobile phone base station uplinks), and 16 mV/m (Wi-Fi 2.4 GHz). Similarly, the median personal exposures were: 81 mV/m (total all bands), 62 mV/m (total mobile phone base station downlinks), 21 mV/m (total mobile phone base station uplinks), and 9 mV/m (Wi-Fi 2.4 GHz). The measurements showed that environmental RF-EMF exposure levels exceeded the personal RF-EMF exposure levels at kindergartens.

  7. A prediction model for personal radio frequency electromagnetic field exposure.

    PubMed

    Frei, Patrizia; Mohler, Evelyn; Bürgi, Alfred; Fröhlich, Jürg; Neubauer, Georg; Braun-Fahrländer, Charlotte; Röösli, Martin

    2009-12-15

    Radio frequency electromagnetic fields (RF-EMF) in our daily life are caused by numerous sources such as fixed site transmitters (e.g. mobile phone base stations) or indoor devices (e.g. cordless phones). The objective of this study was to develop a prediction model which can be used to predict mean RF-EMF exposure from different sources for a large study population in epidemiological research. We collected personal RF-EMF exposure measurements of 166 volunteers from Basel, Switzerland, by means of portable exposure meters, which were carried during one week. For a validation study we repeated exposure measurements of 31 study participants 21 weeks after the measurements of the first week on average. These second measurements were not used for the model development. We used two data sources as exposure predictors: 1) a questionnaire on potentially exposure relevant characteristics and behaviors and 2) modeled RF-EMF from fixed site transmitters (mobile phone base stations, broadcast transmitters) at the participants' place of residence using a geospatial propagation model. Relevant exposure predictors, which were identified by means of multiple regression analysis, were the modeled RF-EMF at the participants' home from the propagation model, housing characteristics, ownership of communication devices (wireless LAN, mobile and cordless phones) and behavioral aspects such as amount of time spent in public transports. The proportion of variance explained (R2) by the final model was 0.52. The analysis of the agreement between calculated and measured RF-EMF showed a sensitivity of 0.56 and a specificity of 0.95 (cut-off: 90th percentile). In the validation study, the sensitivity and specificity of the model were 0.67 and 0.96, respectively. We could demonstrate that it is feasible to model personal RF-EMF exposure. Most importantly, our validation study suggests that the model can be used to assess average exposure over several months.

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

    PubMed

    Floderus; Persson; Stenlund

    1996-07-01

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

  9. Setting prudent public health policy for electromagnetic field exposures.

    PubMed

    Carpenter, David O; Sage, Cindy

    2008-01-01

    Electromagnetic fields (EMF) permeate our environment, coming both from such natural sources as the sun and from manmade sources like electricity, communication technologies and medical devices. Although life on earth would not be possible without sunlight, increasing evidence indicates that exposures to the magnetic fields associated with electricity and to communication frequencies associated with radio, television, WiFi technology, and mobile cellular phones pose significant hazards to human health. The evidence is strongest for leukemia from electricity-frequency fields and for brain tumors from communication-frequency fields, yet evidence is emerging for an association with other diseases as well, including neurodegenerative diseases. Some uncertainty remains as to the mechanism(s) responsible for these biological effects, and as to which components of the fields are of greatest importance. Nevertheless, regardless of whether the associations are causal, the strengths of the associations are sufficiently strong that in the opinion of the authors, taking action to reduce exposures is imperative, especially for the fetus and children. Inaction is not compatible with the Precautionary Principle, as enunciated by the Rio Declaration. Because of ubiquitous exposure, the rapidly expanding development of new EMF technologies and the long latency for the development of such serious diseases as brain cancers, the failure to take immediate action risks epidemics of potentially fatal diseases in the future.

  10. Magnetic field exposure from electric appliances and childhood cancer

    SciTech Connect

    Savitz, D.A.; John, E.M.; Kleckner, R.C. )

    1990-05-01

    The effect on childhood cancer of prolonged exposure to 60-H magnetic fields from electric appliances was examined using interview data from a recently completed case-control study. Exposures of children aged 0-14 years whose incident cancers were diagnosed between 1976 and 1983 and who resided in the Denver, Colorado, Standard Metropolitan Statistical Area were compared with those of controls selected by random digit dialing, matched on age, sex, and telephone exchange area. Parents of 252 cases and 222 controls were interviewed at home about the use of electric appliances by the mother during pregnancy (prenatal exposure) and by the child (postnatal exposure). After adjustment for income, prenatal electric blanket exposure was associated with a small increase in the incidence of childhood cancers (odds ratio (OR) = 1.3, 95% confidence interval (CI) 0.7-2.2) that was more pronounced for leukemia (OR = 1.7, 95% CI 0.8-3.6) and brain cancer (OR = 2.5, 95% CI 1.1-5.5). Postnatal exposure to electric blankets was also weakly associated with childhood cancer (OR = 1.5, 95% CI 0.6-3.4), with a larger but imprecise association with acute lymphocytic leukemia (OR = 1.9, 95% CI 0.6-6.5). Water beds and bedside electric clocks were unrelated to childhood cancer incidence. Results are limited by nonresponse and imprecision resulting from the rarity of appliance use, especially for subgroups of cases. Nonetheless, electric blankets, one of the principal sources of prolonged magnetic field exposure, were weakly associated with childhood cancer and warrant a more thorough evaluation.

  11. Pulse activity of populations of cortical neurons under microwave exposures of different intensity.

    PubMed

    Chizhenkova, R A

    2004-06-01

    In rabbit pulse flows of populations of cortical neurons were investigated prior to, during, and after 1-min microwave irradiation (wavelength 37.5 cm, power density 0.2-40 mW/cm2). It was found that the microwave irradiation produced shifts in mean values of interspike intervals and in the number of spike bursts. Peculiarities of rearrangements of pulse flows of cortical neurons were conditioned by an intensity of exposures.

  12. Effect of electromagnetic field exposure on the reproductive system

    PubMed Central

    Park, Chan Jin

    2012-01-01

    The safety of human exposure to an ever-increasing number and diversity of electromagnetic field (EMF) sources both at work and at home has become a public health issue. To date, many in vivo and in vitro studies have revealed that EMF exposure can alter cellular homeostasis, endocrine function, reproductive function, and fetal development in animal systems. Reproductive parameters reported to be altered by EMF exposure include male germ cell death, the estrous cycle, reproductive endocrine hormones, reproductive organ weights, sperm motility, early embryonic development, and pregnancy success. At the cellular level, an increase in free radicals and [Ca2+]i may mediate the effect of EMFs and lead to cell growth inhibition, protein misfolding, and DNA breaks. The effect of EMF exposure on reproductive function differs according to frequency and wave, strength (energy), and duration of exposure. In the present review, the effects of EMFs on reproductive function are summarized according to the types of EMF, wave type, strength, and duration of exposure at cellular and organism levels. PMID:22563544

  13. Effects of varying argon ion laser intensity and exposure time on the ablation of atherosclerotic plaque.

    PubMed

    Strikwerda, S; Bott-Silverman, C; Ratliff, N B; Goormastic, M; Cothren, R M; Costello, B; Kittrell, C; Feld, M S; Kramer, J R

    1988-01-01

    Using continuous wave (CW) argon ion laser light, a total of 253 laser exposures of varying power (1.5, 3, 5, 8 or 10 W) and duration (20-1,333 ms) were delivered to four segments of human atheromatous aorta obtained at autopsy. Exposure conditions were controlled by using an optically shielded laser catheter that provided a 500 micron spot of light of known power. Two thresholds for consistently reproducible ablation could be defined-an intensity threshold at 25.5 W/mm2 and a fluence threshold at 3.2 J/mm2. Above threshold, a fluence of 5.1 J/mm2 was found to produce the most efficient ablation, ie, removed the greatest volume (mm3) per energy delivered (J) compared to other fluence levels employed (p less than 0.0001). Between aortic segments, however, considerable variability in efficiency (mm3/J) was observed, possibly owing to different optical properties and/or plaque composition. Low-intensity laser radiation produced inconsistent ablation and extensive coagulation effects to surrounding tissue. When a fluence of 5.1 J/mm2 was constructed with a high-intensity laser beam and a short exposure time, consistent and efficient tissue removal resulted without histologic evidence of coagulation necrosis.

  14. Exposure to Drought: Duration, Severity and Intensity (Java, Bali and Nusa Tenggara)

    NASA Astrophysics Data System (ADS)

    Adhyani, N. L.; June, T.; Sopaheluwakan, A.

    2017-03-01

    Occurrence of drought is a slow process lasted for a long time until the rainy season come. This natural disaster has broad and severe impact. This research was conducted to examine the level of severity and intensity of drought in Java, Bali and Nusa Tenggara using Standardized Precipitation Evapotranspiration Index (SPEI). SPEI is drought index used for quantifying drought occurrence, and can be used to analyze duration, severity and intensity. Drought is a climatological phenomenon which is difficult how to determine its onset, duration, magnitude, intensity, spatial extent, etc. Therefore, this information of exposure to drought could be describe the characteristics of drought events. To summarise the calculation, for 30 years (1985-2014) from 22 stations BMKG obtained the longest and strongest drought occurred at meteorology Serang - Banten, with long duration is 11 months and severity - 16.816 at October 2002 until August 2003. In one period of drought event, not always the longest it’s mean the strongest.

  15. Addition of magnetic field capability to existing extremely-low-frequency electric field exposure systems.

    PubMed

    Miller, D L; Miller, M C; Kaune, W T

    1989-01-01

    Magnetic field systems were added to existing electric field exposure apparatuses for exposing cell suspensions in vitro and small animals in vivo. Two horizontally oriented, rectangular coils, stacked one directly above the other, have opposite electric currents. This configuration minimizes leakage fields and allows sham- and field-exposure systems to be placed in the same room or incubator. For the in vitro system, copper plates formed the loop-pair, with up to 900 A supplied by a 180:1 transformer. Electric fields were supplied via electrodes at the ends of cell-culture tubes, eight of which can be accommodated by each exposure system. Two complete systems are situated in an incubator to allow simultaneous sham and field exposure up to 1 mT. For the in vivo system, four pairs of 0.8 x 2.7-m coils made of copper bus bar are employed. This arrangement is energized from the power grid via a 30:1 transformer; horizontal magnetic flux densities up to 1 mT can be generated. Pairs of electrode plates spaced 30.5 cm apart provide electric field exposure of up to 130 kV/m. Four systems with a capacity of 48 rats each are located in one room. For both the in vitro and in vivo systems, magnetic exposure fields are uniform to within +/- 2.5%, and sham levels are at least 2,500-fold lower than exposure levels. Potential confounding factors, such as heating and vibration, were examined and found to be minimal.

  16. [Analysis of methods for measurement and assessment of occupational exposure to electromagnetic fields in dielectric heating].

    PubMed

    Aniołczyk, Halina; Mamrot, Paweł; Mariańska, Magda

    2012-01-01

    High-frequency (HF) welders are the most common devices that make use of dielectric heating. They are a source of high-intensity electromagnetic fields (EMFs). Manual operation of those welders makes that the limbs are exposed to EMFs of extremely high intensity, far in excess of the currently admissible values. The aim of this study was to update knowledge of actual exposure of HF welder operators to EMF and to optimize the procedure of exposure assessment. Measurements of the EMF intensity in the vicinity of 10 dielectric welders at work posts of 12 operators were performed. EMF measurements were made using the reference method, extended by auxiliary measurement points to measure induced currents I(L) in the limbs. Induced current measurements were performed in 20 operators tending the same HF welder. the highest values of the electric (E) and magnetic (H) fields measured at work posts were for whole body: E, up to 350 V/m, and H, up to 1.00 A/m; and for limbs: E, up to 600 V/m and H, up to 3.30 A/m. The W exposure indicator in the primary vertical measurement points was almost as high as 60. I(L) values measured at the wrist exceeded 64 mA and were individual-operator-dependent. EMF exposure of 25% of HF welder operators exceeded the national admissible values and after taking into account the operators' hands, this figure rose to 50%. The measured value of I(L), representing a measure of internal exposure to EMF, should serve as the main criterion in deciding whether working conditions are admissible.

  17. Oil Spill Field Trial at Sea: Measurements of Benzene Exposure.

    PubMed

    Gjesteland, Ingrid; Hollund, Bjørg Eli; Kirkeleit, Jorunn; Daling, Per; Bråtveit, Magne

    2017-07-01

    Characterize personal exposure to airborne hydrocarbons, particularly carcinogenic benzene, during spill of two different fresh crude oils at sea. The study included 22 participants taking part in an «oil on water» field trial in the North Sea. Two types of fresh crude oils (light and heavy) were released six times over two consecutive days followed by different oil spill response methods. The participants were distributed on five boats; three open sampling boats (A, B, and C), one release ship (RS), and one oil recovery (OR) vessel. Assumed personal exposure was assessed a priori, assuming high exposure downwind and close to the oil slick (sampling boats), low exposure further downwind (100-200 m) and upwind from the oil slick (main deck of RS and OR vessel), and background exposure indoors (bridge of RS/OR vessel). Continuous measurements of total volatile organic compounds in isobutylene equivalents were performed with photoionization detectors placed in all five boats. Full-shift personal exposure to benzene, toluene, ethylbenzene, xylenes, naphthalene, and n-hexane was measured with passive thermal desorption tubes. Personal measurements of benzene, averaged over the respective sample duration, on Day 1 showed that participants in the sampling boats (A, B, and C) located downwind and close to the oil slick were highest exposed (0.14-0.59 ppm), followed by participants on the RS main deck (0.02-0.10 ppm) and on the bridge (0.004-0.03 ppm). On Day 2, participants in sampling boat A had high benzene exposure (0.87-1.52 ppm) compared to participants in sampling boat B (0.01-0.02 ppm), on the ships (0.06-0.10 ppm), and on the bridge (0.004-0.01 ppm). Overall, the participants in the sampling boats had the highest exposure to all of the compounds measured. The light crude oil yielded a five times higher concentration of total volatile organic compounds in air in the sampling boats (max 510 ppm) than the heavy crude oil (max 100 ppm) but rapidly declined to <20 ppm

  18. Human exposure to radiofrequency electromagnetic fields. Final rule.

    PubMed

    2013-06-04

    This document resolves several issues regarding compliance with the Federal Communications Commission's (FCC's) regulations for conducting environmental reviews under the National Environmental Policy Act (NEPA) as they relate to the guidelines for human exposure to RF electromagnetic fields. More specifically, the Commission clarifies evaluation procedures and references to determine compliance with its limits, including specific absorption rate (SAR) as a primary metric for compliance, consideration of the pinna (outer ear) as an extremity, and measurement of medical implant exposure. The Commission also elaborates on mitigation procedures to ensure compliances with its limits, including labeling and other requirements for occupational exposure classification, clarification of compliance responsibility at multiple transmitter sites, and labeling of fixed consumer transmitters.

  19. Noise exposure during early development impairs the processing of sound intensity in adult rats.

    PubMed

    Bures, Zbynek; Grécová, Jolana; Popelár, Jirí; Syka, Josef

    2010-07-01

    During the early postnatal development of rats, the structural and functional maturation of the central auditory nuclei strongly relies on the natural character of the incoming neural activity. Even a temporary deprivation in the critical period results in a deterioration of neuronal responsiveness in adult animals. We demonstrate that besides the poorer frequency selectivity of neurons in the impaired animals reported previously [Grecova et al. (2009)Eur. J. Neurosci. 29, 1921-1930], the neuronal representation of sound intensity is significantly affected. Rate-intensity functions of inferior colliculus neurons were recorded in anaesthetized adult rats that were exposed to intense noise at postnatal day 14, and compared with those obtained in age-matched controls. Although the response thresholds were similar in the exposed and control rats, the neurons in the exposed animals had a longer first-spike latency, a narrower dynamic range, lower maximum response magnitudes and a steeper slope of the rate-intensity functions. The percentage of monotonic neurons was significantly lower in the exposed animals. The observed anomalies were confined to the mid- and high-frequency regions, whereas no significant changes were found in the low-frequency neurons. The altered parameters of the individual rate-intensity functions led also to differences in the cumulative responses. We conclude that a brief noise exposure during the critical period leads to a frequency-dependent alteration of the sound intensity representation in the inferior colliculus of adult rats. The results suggest that such impairments may appear in individuals with normal hearing thresholds, but with a history of noise exposure very early in childhood.

  20. Multiple clinical episodes of Plasmodium falciparum malaria in a low transmission intensity setting: exposure versus immunity.

    PubMed

    Rono, Josea; Färnert, Anna; Murungi, Linda; Ojal, John; Kamuyu, Gathoni; Guleid, Fatuma; Nyangweso, George; Wambua, Juliana; Kitsao, Barnes; Olotu, Ally; Marsh, Kevin; Osier, Faith Ha

    2015-05-13

    Epidemiological studies indicate that some children experience many more episodes of clinical malaria than their age mates in a given location. Whether this is as a result of the micro-heterogeneity of malaria transmission with some children effectively getting more exposure to infectious mosquitoes than others, or reflects a failure in the acquisition of immunity needs to be elucidated. Here, we investigated the determinants of increased susceptibility to clinical malaria by comparing the intensity of exposure to Plasmodium falciparum and the acquisition of immunity in children at the extreme ends of the over-dispersed distribution of the incidence of clinical malaria. The study was nested within a larger cohort in an area where the intensity of malaria transmission was low. We identified children who over a five-year period experienced 5 to 16 clinical malaria episodes (children at the tail-end of the over-dispersed distribution, n = 35), remained malaria-free (n = 12) or had a single episode (n = 26). We quantified antibodies against seven Plasmodium falciparum merozoite antigens in plasma obtained at six cross-sectional surveys spanning these five years. We analyzed the antibody responses to identify temporal dynamics that associate with disease susceptibility. Children experiencing multiple episodes of malaria were more likely to be parasite positive by microscopy at cross-sectional surveys (X (2) test for trend 14.72 P = 0.001) and had a significantly higher malaria exposure index, than those in the malaria-free or single episode groups (Kruskal-Wallis test P = 0.009). In contrast, the five-year temporal dynamics of anti-merozoite antibodies were similar in the three groups. Importantly in all groups, antibody levels were below the threshold concentrations previously observed to be correlated with protective immunity. We conclude that in the context of a low malaria transmission setting, susceptibility to clinical malaria is not accounted

  1. Personal radiofrequency electromagnetic field exposure measurements in Swiss adolescents.

    PubMed

    Roser, Katharina; Schoeni, Anna; Struchen, Benjamin; Zahner, Marco; Eeftens, Marloes; Fröhlich, Jürg; Röösli, Martin

    2017-02-01

    Adolescents belong to the heaviest users of wireless communication devices, but little is known about their personal exposure to radiofrequency electromagnetic fields (RF-EMF). The aim of this paper is to describe personal RF-EMF exposure of Swiss adolescents and evaluate exposure relevant factors. Furthermore, personal measurements were used to estimate average contributions of various sources to the total absorbed RF-EMF dose of the brain and the whole body. Personal exposure was measured using a portable RF-EMF measurement device (ExpoM-RF) measuring 13 frequency bands ranging from 470 to 3600MHz. The participants carried the device for three consecutive days and kept a time-activity diary. In total, 90 adolescents aged 13 to 17years participated in the study conducted between May 2013 and April 2014. In addition, personal measurement values were combined with dose calculations for the use of wireless communication devices to quantify the contribution of various RF-EMF sources to the daily RF-EMF dose of adolescents. Main contributors to the total personal RF-EMF measurements of 63.2μW/m(2) (0.15V/m) were exposures from mobile phones (67.2%) and from mobile phone base stations (19.8%). WLAN at school and at home had little impact on the personal measurements (WLAN accounted for 3.5% of total personal measurements). According to the dose calculations, exposure from environmental sources (broadcast transmitters, mobile phone base stations, cordless phone base stations, WLAN access points, and mobile phones in the surroundings) contributed on average 6.0% to the brain dose and 9.0% to the whole-body dose. RF-EMF exposure of adolescents is dominated by their own mobile phone use. Environmental sources such as mobile phone base stations play a minor role. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Quasistatic limit of the strong-field approximation describing atoms in intense laser fields: Circular polarization

    SciTech Connect

    Bauer, Jaroslaw H.

    2011-03-15

    In the recent work of Vanne and Saenz [Phys. Rev. A 75, 063403 (2007)] the quasistatic limit of the velocity gauge strong-field approximation describing the ionization rate of atomic or molecular systems exposed to linearly polarized laser fields was derived. It was shown that in the low-frequency limit the ionization rate is proportional to the laser frequency {omega} (for a constant intensity of the laser field). In the present work I show that for circularly polarized laser fields the ionization rate is proportional to {omega}{sup 4} for H(1s) and H(2s) atoms, to {omega}{sup 6} for H(2p{sub x}) and H(2p{sub y}) atoms, and to {omega}{sup 8} for H(2p{sub z}) atoms. The analytical expressions for asymptotic ionization rates (which become nearly accurate in the limit {omega}{yields}0) contain no summations over multiphoton contributions. For very low laser frequencies (optical or infrared) these expressions usually remain with an order-of-magnitude agreement with the velocity gauge strong-field approximation.

  3. 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.

  4. Development of reading ability is facilitated by intensive exposure to a digital children's picture book

    PubMed Central

    Masataka, Nobuo

    2014-01-01

    Here the author presents preliminary evidence supporting the possibility that the reading ability of 4-year-old children can be improved as a consequence of intensive exposure to the narrative in a digital picture book over a consecutive 5-day period. When creating the digital version used here, two additional functions were provided with it. First, the entire story was voice-recorded by a professional narrator and programmed so that it was played as narration from the speaker of an iPad. Next, as the narration of each digitized page proceeded, the character exactly corresponding to that pronounced by the narrator at that moment became highlighted in red. When the subjects' literacy capability with respect to the syllabic script of the Japanese language (kana) was evaluated before and after the exposure, their performance score was found to increase after the exposure to the digital book, whereas such a change was not recorded in children who experienced exposure to the printed version of the same picture book read to them by their mother. These effects were confirmed when the children were retested 4 weeks later. Although preliminary, the current study represents the first experimental evidence for a positive effect of exposure to digital books upon any aspect of child development. PMID:24822051

  5. Development of reading ability is facilitated by intensive exposure to a digital children's picture book.

    PubMed

    Masataka, Nobuo

    2014-01-01

    Here the author presents preliminary evidence supporting the possibility that the reading ability of 4-year-old children can be improved as a consequence of intensive exposure to the narrative in a digital picture book over a consecutive 5-day period. When creating the digital version used here, two additional functions were provided with it. First, the entire story was voice-recorded by a professional narrator and programmed so that it was played as narration from the speaker of an iPad. Next, as the narration of each digitized page proceeded, the character exactly corresponding to that pronounced by the narrator at that moment became highlighted in red. When the subjects' literacy capability with respect to the syllabic script of the Japanese language (kana) was evaluated before and after the exposure, their performance score was found to increase after the exposure to the digital book, whereas such a change was not recorded in children who experienced exposure to the printed version of the same picture book read to them by their mother. These effects were confirmed when the children were retested 4 weeks later. Although preliminary, the current study represents the first experimental evidence for a positive effect of exposure to digital books upon any aspect of child development.

  6. Exposure to Bisphenol A and Other Phenols in Neonatal Intensive Care Unit Premature Infants

    PubMed Central

    Calafat, Antonia M.; Weuve, Jennifer; Ye, Xiaoyun; Jia, Lily T.; Hu, Howard; Ringer, Steven; Huttner, Ken; Hauser, Russ

    2009-01-01

    Objective We previously demonstrated that exposure to polyvinyl chloride plastic medical devices containing di(2-ethylhexyl) phthalate (DEHP) was associated with higher urinary concentrations of several DEHP metabolites in 54 premature infants in two neonatal intensive care units than in the general population. For 42 of these infants, we evaluated urinary concentrations of several phenols, including bisphenol A (BPA), in association with the use of the same medical devices. Measurements We measured the urinary concentrations of free and total (free plus conjugated) species of BPA, triclosan, benzophenone-3, methyl paraben, and propyl paraben. Results The percentage of BPA present as its conjugated species was > 90% in more than three-quarters of the premature infants. Intensity of use of products containing DEHP was strongly associated with BPA total concentrations but not with any other phenol. Adjusting for institution and sex, BPA total concentrations among infants in the group of high use of DEHP-containing products were 8.75 times as high as among infants in the low use group (p < 0.0001). Similarly, after adjusting for sex and DEHP-containing product use category, BPA total concentrations among infants in Institution A were 16.6 times as high as those among infants in Institution B (p < 0.0001). Conclusion BPA geometric mean urinary concentration (30.3 μg/L) among premature infants undergoing intensive therapeutic medical interventions was one order of magnitude higher than that among the general population. Conjugated species were the primary urinary metabolites of BPA, suggesting that premature infants have some capacity to metabolize BPA. The differences in exposure to BPA by intensity of use of DEHP-containing medical products highlight the need for further studies to determine the specific source(s) of exposure to BPA. PMID:19440505

  7. Exposure to bisphenol A and other phenols in neonatal intensive care unit premature infants.

    PubMed

    Calafat, Antonia M; Weuve, Jennifer; Ye, Xiaoyun; Jia, Lily T; Hu, Howard; Ringer, Steven; Huttner, Ken; Hauser, Russ

    2009-04-01

    We previously demonstrated that exposure to polyvinyl chloride plastic medical devices containing di(2-ethylhexyl) phthalate (DEHP) was associated with higher urinary concentrations of several DEHP metabolites in 54 premature infants in two neonatal intensive care units than in the general population. For 42 of these infants, we evaluated urinary concentrations of several phenols, including bisphenol A (BPA), in association with the use of the same medical devices. We measured the urinary concentrations of free and total (free plus conjugated) species of BPA, triclosan, benzophenone-3, methyl paraben, and propyl paraben. The percentage of BPA present as its conjugated species was > 90% in more than three-quarters of the premature infants. Intensity of use of products containing DEHP was strongly associated with BPA total concentrations but not with any other phenol. Adjusting for institution and sex, BPA total concentrations among infants in the group of high use of DEHP-containing products were 8.75 times as high as among infants in the low use group (p < 0.0001). Similarly, after adjusting for sex and DEHP-containing product use category, BPA total concentrations among infants in Institution A were 16.6 times as high as those among infants in Institution B (p < 0.0001). BPA geometric mean urinary concentration (30.3 microg/L) among premature infants undergoing intensive therapeutic medical interventions was one order of magnitude higher than that among the general population. Conjugated species were the primary urinary metabolites of BPA, suggesting that premature infants have some capacity to metabolize BPA. The differences in exposure to BPA by intensity of use of DEHP-containing medical products highlight the need for further studies to determine the specific source(s) of exposure to BPA.

  8. Estimating magnetic field exposures of rail maintenance workers.

    PubMed

    Wenzl, T B

    1997-09-01

    A measurement survey was undertaken to estimate exposures to 25 hertz (Hz) magnetic fields of maintenance workers on electrified rail lines near Philadelphia, Pa. Because of the mix of frequencies expected, a strategy was developed using new instrument to capture magnetic field waveforms, which were then analyzed by fast Fourier transform for their frequency components. This instrument could only take spot measurements, so a personal monitor repeatedly measured magnetic fields in the ranges of 40-100 Hz. To power trains in the mid-Atlantic region, electrical current flows from the overhead catenary to the locomotive and returns through the rails in a loop up to 10 miles long. This flowing current was the primary source of the magnetic field exposures when a train was near the maintenance work site being measured. A total of 93 spot measurements was taken at five locations. Peak magnetic flux densities ranged from 34 to 185 milligauss (mG) near a transformer, while medians at the five locations ranged from 6.5 to 40 mG. Time-weighted average personal exposures were estimated by combining spot measurements at occupied locations, with estimates of how much time was spent at each location. These averages were estimated to lie between 3.0 and 18 mG, depending on the location of how often trains passed the work site. Comparisons between the spot measurements in the 40-100 Hz frequency range and summarises from the personal dosimeter showed reasonably good agreement. Further characterization of personal exposures in this region may be justified, since on-train workers and passengers may be more highly exposed.

  9. Tumor promotion by exposure to radiofrequency electromagnetic fields below exposure limits for humans.

    PubMed

    Lerchl, Alexander; Klose, Melanie; Grote, Karen; Wilhelm, Adalbert F X; Spathmann, Oliver; Fiedler, Thomas; Streckert, Joachim; Hansen, Volkert; Clemens, Markus

    2015-04-17

    The vast majority of in vitro and in vivo studies did not find cancerogenic effects of exposure to electromagnetic fields (RF-EMF), i.e. emitted by mobile phones and base stations. Previously published results from a pilot study with carcinogen-treated mice, however, suggested tumor-promoting effects of RF-EMF (Tillmann et al., 2010). We have performed a replication study using higher numbers of animals per group and including two additional exposure levels (0 (sham), 0.04, 0.4 and 2 W/kg SAR). We could confirm and extend the originally reported findings. Numbers of tumors of the lungs and livers in exposed animals were significantly higher than in sham-exposed controls. In addition, lymphomas were also found to be significantly elevated by exposure. A clear dose-response effect is absent. We hypothesize that these tumor-promoting effects may be caused by metabolic changes due to exposure. Since many of the tumor-promoting effects in our study were seen at low to moderate exposure levels (0.04 and 0.4 W/kg SAR), thus well below exposure limits for the users of mobile phones, further studies are warranted to investigate the underlying mechanisms. Our findings may help to understand the repeatedly reported increased incidences of brain tumors in heavy users of mobile phones.

  10. Cell membrane potentials induced during exposure to EMP fields

    SciTech Connect

    Gailey, P.C.; Easterly, C.E.

    1994-09-01

    Internal current densities and electric fields induced in the human body during exposure to EMP fields are reviewed and used to predict resulting cell membrane potentials. Using several different approaches, membrane potentials of about 100 mV are predicted. These values are comparable to the static membrane potentials maintained by cells as a part of normal physiological function, but the EMP-induced potentials persist for only about 10 ns. Possible biological implications of EMP-induced membrane potentials including conformational changes and electroporation are discussed.

  11. Validity and Reliability of Exposure Assessors’ Ratings of Exposure Intensity by Type of Occupational Questionnaire and Type of Rater

    PubMed Central

    Friesen, Melissa C.; Coble, Joseph B.; Katki, Hormuzd A.; Ji, Bu-Tian; Xue, Shouzheng; Stewart, Patricia A.

    2011-01-01

    Background: In epidemiologic studies that rely on professional judgment to assess occupational exposures, the raters’ accurate assessment is vital to detect associations. We examined the influence of the type of questionnaire, type of industry, and type of rater on the raters’ ability to reliably and validly assess within-industry differences in exposure. Our aim was to identify areas where improvements in exposure assessment may be possible. Methods: Subjects from three foundries (n = 72) and three textile plants (n = 74) in Shanghai, China, completed an occupational history (OH) and an industry-specific questionnaire (IQ). Six total dust measurements were collected per subject and were used to calculate a subject-specific measurement mean, which was used as the gold standard. Six raters independently ranked the intensity of each subject’s current job on an ordinal scale (1–4) based on the OH alone and on the OH and IQ together. Aggregate ratings were calculated for the group, for industrial hygienists, and for occupational physicians. We calculated intra-class correlation coefficients (ICCs) to evaluate the reliability of the raters. We calculated the correlation between the subject-specific measurement means and the ratings to evaluate the raters’ validity. Analyses were stratified by industry, type of questionnaire, and type of rater. We also examined the agreement between the ratings by exposure category, where the subject-specific measurement means were categorized into two and four categories. Results: The reliability and validity measures were higher for the aggregate ratings than for the ratings from the individual raters. The group’s performance was maximized with three raters. Both the reliability and validity measures were higher for the foundry industry than for the textile industry. The ICCs were consistently lower in the OH/IQ round than in the OH round in both industries. In contrast, the correlations with the measurement means were

  12. Effects of intense magnetic fields on sedimentation pattern and gene expression profile in budding yeast

    NASA Astrophysics Data System (ADS)

    Ikehata, Masateru; Iwasaka, Masakazu; Miyakoshi, Junji; Ueno, Shoogo; Koana, Takao

    2003-05-01

    Effects of magnetic fields (MFs) on biological systems are usually investigated using biological indices such as gene expression profiles. However, to precisely evaluate the biological effects of MF, the effects of intense MFs on systematic material transport processes including experimental environment must be seriously taken into consideration. In this study, a culture of the budding yeast, Saccharomyces cerevisiae, was used as a model for an in vitro biological test system. After exposure to 5 T static vertical MF, we found a difference in the sedimentation pattern of cells depending on the location of the dish in the magnet bore. Sedimented cells were localized in the center of the dish when they were placed in the lower part of the magnet bore while the sedimentation of the cells was uniform in dishes placed in the upper part of the bore because of the diamagnetic force. Genome wide gene expression profile of the yeast cells after exposure to 5 T static MF for 2 h suggested that the MF did not affect the expression level of any gene in yeast cells although the sedimentation pattern was altered. In addition, exposure to 10 T for 1 h and 5 T for 24 h also did not affect the gene expression. On the other hand, a slight change in expressions of several genes which are related to respiration was observed by exposure to a 14 T static MF for 24 h. The necessity of estimating the indirect effects of MFs on a study of its biological effect of MF in vitro will be discussed.

  13. 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

  14. 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.

  15. Individual estimation of exposures to extremely low frequency magnetic fields in jobs commonly held by women.

    PubMed

    Deadman, J E; Infante-Rivard, C

    2002-02-15

    Exposures to extremely low frequency (ELF) magnetic fields have not been documented extensively in occupations besides the work environments of electric or telephone utilities. A 1980-1993 study of childhood acute lymphoblastic leukemia (ALL) in Québec, Canada, gathered detailed information about the occupations of 491 mothers of ALL cases and mothers of a similar number of healthy controls. This information was combined with published data on the intensities of ELF magnetic fields associated with sources or work environments to estimate ELF magnetic field exposures for a wide range of jobs commonly held by women. Estimated exposures for 61 job categories ranged from 0.03 to 0.68 microT; the 25th, 50th, and 75th percentiles were 0.135, 0.17, and 0.23 microT, respectively. By job category, the most highly exposed jobs (>0.23 microT) included bakery worker, cashier, cook and kitchen worker, electronics worker, residential and industrial sewing machine operator, and textile machine operator. By work environment, the most highly exposed job categories were electronics worker in an assembly plant (0.70 microT) and sewing machine operators in a textile factory (0.68 microT) and shoe factory (0.66 microT). These results provide new information on expected levels of exposure in a wide range of jobs commonly held by women.

  16. 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

  17. Spectral analysis to assess exposure to extremely low frequency magnetic fields in cars.

    PubMed

    Paniagua, Jesús M; Rufo, Montaña; Jiménez, Antonio; Antolín, Alicia; Barberá, Jorge

    2017-04-15

    A type of contamination that has been little studied in cars comes from the extremely low frequency (ELF) magnetic fields generated by the vehicle's electrical devices and the magnetized metal in the tyres. The magnetic fields in cars are frequently analysed with broadband meters sensitive to a frequency range above 30Hz. This has the disadvantage that they neither detect the magnetic field of the spinning tyres nor give any information on the spectral components, which makes it impossible to adequately assess exposure. The objective of the present study was to perform spectral analyses of ELF magnetic fields in cars, to identify their frequencies, and to assess exposure based on the ICNIRP regulatory guidelines. To do this, a meter and a spectrum analyser sensitive to magnetic fields in the 5Hz-2kHz frequency range were used. Spectra were acquired for different seats, heights, and speeds, and spatially averaged exposure coefficients were calculated. The results indicated that the main emissions were detected in the 5-100Hz range, where the wheel rotation frequencies and their harmonics are found. The intensity of the rest of the emissions were negligible in comparison. The exposure quotient increases with speed, and is approximately twice as great at foot level as at head level. The magnetic field levels are lower than the reference levels (the maximum represents 3% of the ICNIRP standard), but higher than those found in residential environments and than the cut-off threshold used by the IARC to classify ELF magnetic fields in Group 2B. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Prostate Cancer and Ambient Pesticide Exposure in Agriculturally Intensive Areas in California

    PubMed Central

    Cockburn, Myles; Mills, Paul; Zhang, Xinbo; Zadnick, John; Goldberg, Dan; Ritz, Beate

    2011-01-01

    In a population-based case-control study in California's intensely agricultural Central Valley (2005–2006), the authors investigated relations between environmental pesticide/fungicide exposure and prostate cancer. Cases (n = 173) were obtained from a population-based cancer registry, and controls (n = 162) were obtained from Medicare listings and tax assessor mailings. Past ambient exposures to pesticides/fungicides were derived from residential history and independently recorded pesticide and land-use data, using a novel geographic information systems approach. In comparison with unexposed persons, increased risks of prostate cancer were observed among persons exposed to compounds which may have prostate-specific biologic effects (methyl bromide (odds ratio = 1.62, 95% confidence interval: 1.02, 2.59) and a group of organochlorines (odds ratio = 1.64, 95% confidence interval: 1.02, 2.63)) but not among those exposed to other compounds that were included as controls (simazine, maneb, and paraquat dichloride). The authors assessed the possibility of selection bias due to less-than-100% enrollment of eligible cases and controls (a critical methodological concern in studies of this kind) and determined that there was little evidence of bias affecting the estimated effect size. This study provides evidence of an association between prostate cancer and ambient pesticide exposures in and around homes in intensely agricultural areas. The associations appear specific to compounds with a plausible biologic role in prostate carcinogenesis. PMID:21447478

  19. Increasing Availability of Exposure Therapy Through Intensive Group Treatment for Childhood Anxiety and OCD.

    PubMed

    Whiteside, Stephen P H; Dammann, Julie E; Tiede, Michael S; Biggs, Bridget K; Hillson Jensen, Andrea

    2017-09-01

    Archival data were used to examine the feasibility of a 5-day, clinic-based, intensive exposure-based cognitive-behavioral group therapy for childhood anxiety disorders (CADs) and obsessive-compulsive disorder (OCD). Participants were 143 children (82 girls) aged 6 to 19 years ( M = 13.93 years, SD = 2.9 years) with CADs or OCD (or both) in 28 consecutive groups. Repeated-measures ANOVA in the subsample ( n = 57) with complete treatment data indicated positive change on all variables from pretreatment to posttreatment with few differences between CADs and OCD patients. Effect sizes were moderate to large for anxiety symptoms (parent reported = 0.74, child reported = 0.65) and impairment (parent reported = 1.02, child reported = 0.69). The intensive group protocol required fewer sessions and 36% fewer therapist-hours per patient than the individually administered protocol. The program increased treatment availability for families from diverse geographic areas ( M distance traveled to clinic = 407 miles, SD = 786.4 miles). These findings support further, well-controlled examination of the 5-day intensive group treatment protocol's efficacy and potential to increase availability of evidence-based exposure therapy.

  20. Histologic study of the internal organs of rats chronically exposed to a high-intensity electric field

    SciTech Connect

    Seto, Y.J.; Majeau-Chargois, D.; Lymangrover, J.R.; Dunlap, W.P.; Hsieh, S.T.

    1985-01-01

    The effect of 120-day exposure to a high-intensity (80 kV/m), 60-Hz electric field on histology of selected internal organs of Sprague-Dawley rats was investigated. The organs examined were the pituitary, thymus, heart, lungs, liver, spleen, right and left adrenals, right and left kidneys, and right and left testes. Histological examination of 10-micron tissue sections from randomly selected animals revealed no specific evidence of histopathologic differences between field-exposed and sham-exposed animals at the light microscopic level.

  1. Low intensity, long term exposure to tobacco smoke inhibits hippocampal neurogenesis in adult mice.

    PubMed

    Csabai, Dávid; Csekő, Kata; Szaiff, Lilla; Varga, Zsófia; Miseta, Attila; Helyes, Zsuzsanna; Czéh, Boldizsár

    2016-04-01

    Previous data have shown that high dose of nicotine administration or tobacco smoke exposure can reduce cell formation and the survival rate of adult-born neurons in the dentate gyrus. Here, we subjected adult mice to low intensity cigarette smoke exposure over long time periods. We did a 2×30min/day smoke exposure with two cigarettes per occasion over 1- or 2-months. Subsequently, we carried out a systematic quantitative histopathological analysis to assess the number of newborn neurons in the dentate gyrus. To investigate cell proliferation, the exogenous marker 5-bromo-2'-deoxyuridine (BrdU) was administered on the last experimental day and animals were sacrificed 2h later. To investigate the effect of tobacco smoke on the population of immature neurons, we quantified the number of doublecortin-positive (DCX+) neurons in the same animals. We found that exposing animals to cigarette smoke for 1- or 2-months had no influence on cell proliferation rate, but significantly reduced the number of DCX-positive immature neurons. Our tobacco smoke exposure regimen caused no substantial changes in respiratory functions, but histopathological analysis of the pulmonary tissue revealed a marked perivascular/peribronchial edema formation after 1-month and signs of chronic pulmonary inflammation after 2-months of cigarette smoke exposure. These data demonstrate that even mild exposure to cigarette smoke, without significantly affecting respiratory functions, can have a negative effect on adult-born neurons in the dentate gyrus, when applied over longer time periods. Our data indicate that besides nicotine other factors, such as inflammatory mediators, may also contribute to this effect.

  2. Effect of duration and intensity of ganciclovir exposure on lymphoblastoid cell toxicity.

    PubMed

    Janoly-Dumenil, Audrey; Rouvet, Isabelle; Bleyzac, Nathalie; Bertrand, Yves; Aulagner, Gilles; Zabot, Marie-Thérèse

    2009-01-01

    Human cytomegalovirus infection is still a major complication after pediatric bone marrow transplantation and could be fatal in some cases. The toxicity of the drug in dividing transplanted haematopoietic cells combined with the suppression of cell growth caused by the virus remains a major problem in managing human cytomegalovirus infection. The aim of the current in vitro study was to evaluate the effect of the intensity (1-20 mg/l) and duration (1, 2, 7 or 14 days) of ganciclovir exposure on toxicity in B lymphoblastoid cells (using cell counting and viability measurements). A correlation was found between the dose of ganciclovir exposure and a decrease in total cell number when duration exceeded 2 days (r(2)=0.92 and 0.93 after 7 and 14 days, respectively). High levels (20 mg/l) of ganciclovir were not more toxic than lowest levels (1 mg/l) for the shortest durations of ganciclovir exposure (1 and 2 days). Moreover, 50% cytotoxic concentrations markedly decreased with the duration of ganciclovir exposure (374-3 mg/l from 1 to 14 days respectively) after 14 days of culture. This in vitro study demonstrated for the first time that ganciclovir exhibited an in vitro duration-dependent toxicity on haematopoietic-derived cells when in vivo doses of the drug were used.

  3. Electromagnetic field occupational exposure: non-thermal vs. thermal effects.

    PubMed

    Israel, M; Zaryabova, V; Ivanova, M

    2013-06-01

    There are a variety of definitions for "non-thermal effects" included in different international standards. They start by the simple description that they are "effects of electromagnetic energy on a body that are not heat-related effects", passing through the very general definition related to low-level effects: "biological effects ascribed to exposure to low-level electric, magnetic and electromagnetic fields, i.e. at or below the corresponding dosimetric reference levels in the frequency range covered in this standard (0 Hz-300 GHz)", and going to the concrete definition of "the stimulation of muscles, nerves, or sensory organs, vertigo or phosfenes". Here, we discuss what kind of effect does the non-thermal one has on human body and give data of measurements in different occupations with low-frequency sources of electromagnetic field such as electric power distribution systems, transformers, MRI systems and : video display units (VDUs), whereas thermal effects should not be expected. In some of these workplaces, values above the exposure limits could be found, nevertheless that they are in the term "non-thermal effects" on human body. Examples are workplaces in MRI, also in some power plants. Here, we will not comment on non-thermal effects as a result of RF or microwave exposure because there are not proven evidence about the existance of such effects and mechanisms for them are not clear.

  4. DNA Electrophoretic Migration Patterns Change after Exposure of Jurkat Cells to a Single Intense Nanosecond Electric Pulse

    PubMed Central

    Romeo, Stefania; Zeni, Luigi; Sarti, Maurizio; Sannino, Anna; Scarfì, Maria Rosaria; Vernier, P. Thomas; Zeni, Olga

    2011-01-01

    Intense nanosecond pulsed electric fields (nsPEFs) interact with cellular membranes and intracellular structures. Investigating how cells respond to nanosecond pulses is essential for a) development of biomedical applications of nsPEFs, including cancer therapy, and b) better understanding of the mechanisms underlying such bioelectrical effects. In this work, we explored relatively mild exposure conditions to provide insight into weak, reversible effects, laying a foundation for a better understanding of the interaction mechanisms and kinetics underlying nsPEF bio-effects. In particular, we report changes in the nucleus of Jurkat cells (human lymphoblastoid T cells) exposed to single pulses of 60 ns duration and 1.0, 1.5 and 2.5 MV/m amplitudes, which do not affect cell growth and viability. A dose-dependent reduction in alkaline comet-assayed DNA migration is observed immediately after nsPEF exposure, accompanied by permeabilization of the plasma membrane (YO-PRO-1 uptake). Comet assay profiles return to normal within 60 minutes after pulse delivery at the highest pulse amplitude tested, indicating that our exposure protocol affects the nucleus, modifying DNA electrophoretic migration patterns. PMID:22164287

  5. Chrome tannage using high-intensity ultrasonic field.

    PubMed

    Mäntysalo, E; Marjoniemi, M; Kilpeläinen, M

    1997-04-01

    The process time in chrome tannage in leather making, using an elastic compression cycle followed by irradiation by high-intensity ultrasound, is quite short lasting only a few minutes, compared with a process time of several hours in modern chrome tannage. After ultrasonic irradiation, samples were basified in 17 h in chrome liquor at a pH of 4.0 and the shrinkage temperature was measured. The determination of the efficiency for the chrome liquor penetrating into the hides can be based on the steepness of the shrinkage temperature-processing time curve. An approximate value of 20 degrees C min(-1) can be evaluated for the initial slope of the curve when elastic compression and high-intensity ultrasonic irradiation is used, and a processing time of 2 min is required in chrome liquor (plus 17 h basification and 24 h storage time) to obtain leather stable to boiling. Usually, hides are kept in chrome liquor for 2 h.

  6. 14 CFR 23.1308 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF... Equipment General § 23.1308 High-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in... reduce the capability of the airplane or the ability of the flightcrew to respond to an adverse...

  7. 14 CFR 29.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF...-intensity Radiated Fields (HIRF) Protection. (a) Except as provided in paragraph (d) of this section, each... equipment HIRF test level 1 or 2, as described in appendix E to this part. (c) Each electrical and...

  8. Lagrangian Formulation of Relativistic Particle Average Motion in a Laser Field of Arbitrary Intensity

    SciTech Connect

    I.Y. Dodin; N.J. Fisch; G.M. Fraiman

    2003-02-06

    The Lagrangian and Hamiltonian functions describing average motion of a relativistic particle under the action of intensive high-frequency electromagnetic radiation are obtained. In weak, low-frequency background fields, such a particle on average drifts with an effective, relativistically invariant mass, which depends on the intensity of the electromagnetic field.

  9. Dissociative ionization of acetonitrile in intense femtosecond laser fields

    NASA Astrophysics Data System (ADS)

    Boran, Y.; Kolomenskii, A. A.; Sayrac, M.; Kaya, N.; Schuessler, H. A.; Strohaber, J.

    2017-07-01

    We investigate the formation of positively charged fragments of acetonitrile (CH3CN) in intense 800 nm, 50 fs pulses of radiation using a reflectron time-of-flight (TOF) ion mass spectrometer. Singly-charged ions of CHnCN+ (n={0-3}), HCN+, CN+, {{{{CH}}}3}+, {{{{CH}}}2}+, CH+, C+ and H+; and the multiply charged ions of C2+, C3+, {{{{CH}}}2}2+, and {{{{CH}}}2}3+ were observed in the mass spectra. Quantum chemical calculations with GAMESS (General Atomic and Molecular Electronic Structure System) of appearance energies for the parent molecule and daughter fragments have been carried out. Intensity dependent ion yields were measured for intensities between 4.4× {10}13 {{W}} {{{cm}}}-2 and 3.3× {10}14 {{W}} {{{cm}}}-2. Angular distributions of most fragment ions were found to peak when the laser radiation was polarized parallel to the TOF axis, while the carbon ions, C+ and C2+, were found to have maxima for both polarizations parallel and perpendicular to this axis. Kinetic energies of H+ fragments were experimentally measured and three different photo dissociation mechanisms were identified.

  10. Interaction of Clusters with Intense, Few-Cycle, Long Wavelength Fields

    DTIC Science & Technology

    2015-11-05

    AFRL-AFOSR-VA-TR-2015-0362 Interaction of clusters with intense, few-cycle, long wavelength fields Louis DiMauro OHIO STATE UNIVERSITY THE Final...to Dr. Enrique Parra Contract/Grant Title: Interaction of clusters with intense, few-cycle, long wavelength fields. Contract/Grant #: FA9550-12-1...plans for the study of intense laser- cluster interactions. First, we have finished the construction of a time-of-flight (TOF) cluster beam machine

  11. Light-front time evolution in intense fields

    NASA Astrophysics Data System (ADS)

    Chen, Guangyao; Zhao, Xingbo; Li, Yang; Maris, Pieter; Tuchin, Kirill; Vary, James

    2016-03-01

    We report on the influence of strong electromagnetic fields generated by an ultra-relativistic heavy ion on the quantized field of a charged fermion particle using the time-dependent basis light-front quantization (tBLFQ) approach. We calculate transitions of the charged fermion and find agreement with light-front perturbation theory at small coupling. We then present non-perturbative effects, such as the real-time evolution of the momentum distribution and the helicity configuration of the fermion in strong fields. We will discuss prospects for applying the tBLFQ formalism to time-dependent QED and QCD fields in heavy ion collisions and electron-ion collisions. This work is supported by DOE Grants DE-FG02-87ER40371 & DESC0008485.

  12. Paternal occupational exposure to electromagnetic fields and neuroblastoma in offspring

    SciTech Connect

    Wilkins, J.R. 3d.; Hundley, V.D. )

    1990-06-01

    Investigators in Texas have reported an association between paternal employment in jobs linked with exposure to electromagnetic fields and risk of neuroblastoma in offspring. In an attempt to replicate this finding, the authors conducted a case-control study in Ohio. A total of 101 incident cases of neuroblastoma were identified through the Columbus (Ohio) Children's Hospital Tumor Registry. All cases were born sometime during the period 1942-1967. From a statewide roster of birth certificates, four controls were selected for each case, with individual matching on the case's year of birth, race, and sex, and the mother's county of residence at the time of the (index) child's birth. Multiple definitions were employed to infer the potential for paternal occupational exposure to electromagnetic fields from the industry/occupation statements on the birth certificates. Case-control comparisons revealed adjusted odds ratios ranging in magnitude from 0.5 to 1.9. For two of the exposure definitions employed--both of which are similar to one used by the Texas investigators--the corresponding odds ratios were modestly elevated (odds ratios = 1.6 and 1.9). Notably, the magnitude of these odds ratios is not inconsistent with the Texas findings, where the exposure definition referred to yielded an odds ratio of 2.1. Because the point estimates in this study are imprecise, and because the biologic plausibility of the association is uncertain, the results reported here must be interpreted cautiously. However, the apparent consistency between two independent studies suggests that future evaluation of the association is warranted.

  13. Mesons in ultra-intense magnetic field: an evaded collapse

    NASA Astrophysics Data System (ADS)

    Kerbikov, B. O.; Andreichikov, M. A.; Simonov, Yu. A.

    2017-03-01

    Spectra of qq¯ mesons are investigated in the framework of the Hamiltonian obtained from the relativistic path integral in external homogeneous magnetic field. The spectra of all 12 spin-isospin s-wave states generated by π- and ρ-mesons with different spin projections, are studied analytically as functions of the field strength. Three types of behavior with characteristic splittings are found. The results are in agreement with recent lattice calculations.

  14. The effects of exposure to electromagnetic field on rat myocardium.

    PubMed

    Kiray, Amac; Tayefi, Hamid; Kiray, Muge; Bagriyanik, Husnu Alper; Pekcetin, Cetin; Ergur, Bekir Ugur; Ozogul, Candan

    2013-06-01

    Exposure to electromagnetic fields (EMFs) causes increased adverse effects on biological systems. The aim of this study was to investigate the effects of EMF on heart tissue by biochemical and histomorphological evaluations in EMF-exposed adult rats. In this study, 28 male Wistar rats weighing 200-250 g were used. The rats were divided into two groups: sham group (n = 14) and EMF group (n = 14). Rats in sham group were exposed to same conditions as the EMF group except the exposure to EMF. Rats in EMF group were exposed to a 50-Hz EMF of 3 mT for 4 h/day and 7 days/week for 2 months. After 2 months of exposure, rats were killed; the hearts were excised and evaluated. Determination of oxidative stress parameters was performed spectrophotometrically. To detect apoptotic cells, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining and caspase-3 immunohistochemistry were performed. In EMF-exposed group, levels of lipid peroxidation significantly increased and activities of superoxide dismutase and glutathione peroxidase decreased compared with sham group. The number of TUNEL-positive cells and caspase-3 immunoreactivity increased in EMF-exposed rats compared with sham. Under electron microscopy, there were mitochondrial degeneration, reduction in myofibrils, dilated sarcoplasmic reticulum and perinuclear vacuolization in EMF-exposed rats. In conclusion, the results show that the exposure to EMF causes oxidative stress, apoptosis and morphologic damage in myocardium of adult rats. The results of our study indicate that EMF-related changes in rat myocardium could be the result of increased oxidative stress. Further studies are needed to demonstrate whether the exposure to EMF can induce adverse effects on myocardium.

  15. Personal UV exposure on a ski-field at an alpine site

    NASA Astrophysics Data System (ADS)

    Siani, A. M.; Casale, G. R.; Diémoz, H.; Agnesod, G.; Kimlin, M. G.; Lang, C. A.; Colosimo, A.

    2008-02-01

    Mountain sites experience enhanced ambient UV radiation levels due to the concurrent effects of shorter radiation path-length, low aerosol load and high reflectivity of the snow surfaces. This study was encouraged by the possibility to collect data of personal UV exposure in the mountainous areas of Italy, for the first time. Personal UV exposure (expressed in terms of Exposure Ratio, ER) of two groups of volunteers (ski instructors and skiers) at the Alpine site of La Thuile (Valle d'Aosta region, Italy) was assessed using polysulphone dosimetry which was tested in a mountainous snow-covered environment. In addition measurements of biological markers of individual response to UV exposure such as skin colorimetric parameters were carried out. It was found that snow and altitude of study site affect calibration curves of polysulphone dosimeters in comparison to a situation without snow. The median ER, taking into account the whole sample, is 0.60 in winter, with a range of 0.29 to 1.46, and 1.02 in spring, ranging from 0.46 to 1.72. There are no differences in exposures across skiers and instructors in spring while in winter skiers experience lower values. UV exposures are not sensitive to the use of sunscreen across instructor/skier group by day or by seasons or by photo-type. With regard to colorimetric parameters, the main result was that both skiers and instructors had on average significantly lower values of L* and b* after exposure i.e. becoming darker but the inappropriate sunscreen use did not reveal any changes in skin colorimetric parameters except in one spring day. In conclusions UV intensities on the ski-fields are often significantly higher than those on horizontal surfaces. Given the high levels of exposure observed in the present study, dedicated public heath messages on the correct sunscreen use should be adopted.

  16. Evaluation of pulsed high intensity focused ultrasound exposures on metastasis in a murine model

    PubMed Central

    Hancock, Hilary; Dreher, Matthew R.; Crawford, Nigel; Pollock, Claire B.; Shih, Jennifer; Wood, Bradford J.; Hunter, Kent; Frenkel, Victor

    2014-01-01

    High intensity focused ultrasound (HIFU) may be employed in two ways: continuous exposures for thermal ablation of tissue (>60°C), and pulsed-exposures for non-ablative effects, including low temperature hyperthermia (37–45°C), and non thermal effects (e.g. acoustic cavitation and radiation forces). Pulsed-HIFU effects may enhance the tissue's permeability for improved delivery of drugs and genes, for example, by opening up gaps between cells in the vasculature and parenchyma. Inducing these effects may improve local targeting of therapeutic agents, however; concerns exist that pulsed exposures could theoretically also facilitate dissemination of tumor cells and exacerbate metastases. In the present study, the influence of pulsed-HIFU exposures on increasing metastatic burden was evaluated in a murine model with metastatic breast cancer. A preliminary study was carried out to validate the model and determine optimal timing for treatment and growth of lung metastases. Next, the effect of pulsed-HIFU on the metastatic burden was evaluated using quantitative image processing of whole-lung histological sections. Compared to untreated controls (2/15), a greater number of mice treated with pulsed-HIFU were found to have lungs “overgrown” with metastases (7/15), where individual metastases grew together such that they could not accurately be counted. Furthermore, area fraction of lung metastases (area of metastases/area of lungs) was ~30% greater in mice treated with pulsed-HIFU; however, these differences were not statistically significant. The present study details the development of an animal model for investigating the influence of interventional techniques or exposures (such as pulsed HIFU) on metastatic burden. PMID:19517258

  17. Calculation of externally applied electric field intensity for disruption of cancer cell proliferation.

    PubMed

    Sardari, Dariush; Verga, Nicolae

    2010-06-01

    It is already known that electrostatic, magnetostatic, extremely low-frequency electric fields, and pulsed electric field could be utilized in cancer treatment. The healing effect depends on frequency and amplitude of electric field. In the present work, a simple theoretical model is developed to estimate the intensity of electrostatic field that damages a living cell during division. By this model, it is shown that magnification of electric field in the bottleneck of dividing cell is enough to break chemical bounds between molecules by an avalanche process. Our model shows that the externally applied electric field of 4 V/cm intensity is able to hurt a cancer cell at the dividing stage.

  18. Effect of Intensive and Repetitive Heat Exposure on the Sudomotor Activity.

    PubMed

    Lee, Jeong Beom; Seo, Hyung Seok; Shin, Young Oh

    2017-10-31

    The sweating response is modulated in two different ways depending on adaptation conditions. In this work, we examined sudomotor activities before and after intensive and repetitive heat exposure. Nine male volunteers were exposed to 30-min half-body immersion in hot water (42 ± 0.5°C) at the same time of day on alternate days for 3 weeks. All experiments were performed in an automated climate chamber. Tympanic (Tty) and skin (Ts) temperatures were measured. Mean body temperature (mTb) was calculated. Sudomotor activities, including sweat onset time, sweat rate and volume, activated sweat gland density (ASGD) and output (ASGO), were tested in four regions of the skin: chest, abdomen, upper back and thigh. Basal Tty and mTb were found to decrease by 0.15°C (P < 0.05) and 0.16°C (P < 0.05), respectively. As a typical data (upper back), sweat onset time increased by 33.6% (P < 0.05) after heat acclimation. After heat acclimation, sweat rate decreased by 14.7% (P < 0.05), sweat volume decreased by 15.5% (P < 0.05) and ASGO also decreased by 11.1% (P < 0.05). ASGD decreased by 4.1% after heat acclimation without statistical significance. The data suggest that intensive and repetitive heat exposure induces suppression of sudomotor activities within 3 weeks.

  19. Effects of exposure to a 60-kV/m, 60-Hz electric field on the social behavior of baboons

    SciTech Connect

    Easley, S.P.; Coelho, A.M. Jr.; Rogers, W.R. )

    1991-01-01

    The authors found in a previously reported study that exposure to a 30-kV/m, 60-Hz electric field had significant effects on the social behavior of baboons. However, it was not established whether or not the effects were related specifically to the 30-kV/m intensity of the field. A new experiment was conducted to determine whether or not exposure to a 60-Hz electric field at 60 kV/m would produce like changes in the baboons' social behavior. They exposed one group of eight male baboons to an electric field 12 hours a day, 7 days a week, for 6 weeks. A second group of eight animals was maintained under sham-exposure (control) conditions. Rates of performing on each of six categories of social behavior and on four categories of nonsocial behavior were used as criteria for comparing exposed with unexposed subjects and for within-group comparisons during three six-week experimental periods: Pre-Exposure, Exposure, and Post-Exposure. The results indicate that (1) during the exposure period, exposed animals exhibited statistically significant differences from controls in means of performance rates based on several behavioral categories; (2) across all three periods, within-group comparisons revealed that behaviors of exposed baboons were significantly affected by exposure to the electric field; (3) changes in performance levels probably reflect a stress response to the electric field; and (4) the means of response rates of animals exposed at 60 kV/m were higher, but not double, those of animals exposed at 30 kV/m. As in the 30-kV/m experiment, animals exposed at 60 kV/m exhibited significant differences in performances of Passive Affinity, Tension, and Stereotypy. Mean rates of performing these categories were 122% (Passive Affinity), 48% (Tension), and 40% (Stereotypy) higher in the exposed group than in the control group during exposure to the 60-kV/m field.

  20. Nonlinear transmission of an intense terahertz field through monolayer graphene

    SciTech Connect

    Hafez, H. A.; Ibrahim, A.; Ozaki, T.; Al-Naib, I.; Dignam, M. M.; Oguri, K.; Sekine, Y.; Hibino, H.; Cooke, D. G.; Tanaka, S.; Komori, F.

    2014-11-15

    We report nonlinear terahertz (THz) effects in monolayer graphene, giving rise to transmission enhancement of a single-cycle THz pulse when the incident THz peak electric field is increased. This transmission enhancement is attributed to reduced photoconductivity, due to saturation effects in the field-induced current and increased intraband scattering rates arising from transient heating of electrons. We have developed a tight-binding model of the response using the length gauge interaction Hamiltonian that provides good qualitative agreement. The model fully accounts for the nonlinear response arising from the linear dispersion energy spectrum in graphene. The results reveal a strong dependence of the scattering time on the THz field, which is at the heart of the observed nonlinear response.

  1. Quantum processes in short and intensive electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Titov, A. I.; Kämpfer, Burkhard; Hosaka, Atsushi; Takabe, Hideaki

    2016-05-01

    This work provides an overview of our recent results in studying two most important and widely discussed quantum processes: electron-positron pairs production off a probe photon propagating through a polarized short-pulsed electromagnetic (e.g. laser) wave field or generalized Breit-Wheeler process, and a single a photon emission off an electron interacting with the laser pules, so-called non-linear Compton scattering. We show that the probabilities of particle production in both processes are determined by interplay of two dynamical effects, where the first one is related to the shape and duration of the pulse and the second one is non-linear dynamics of the interaction of charged fermions with a strong electromagnetic field. We elaborate suitable expressions for the production probabilities and cross sections, convenient for studying evolution of the plasma in presence of strong electromagnetic fields.

  2. Alignment of the hydrogen molecule under intense laser fields

    NASA Astrophysics Data System (ADS)

    Lopez, Gary V.; Fournier, Martin; Jankunas, Justin; Spiliotis, Alexandros K.; Rakitzis, T. Peter; Chandler, David W.

    2017-07-01

    Alignment of the electronically excited E,F state of the H2 molecule is studied using the velocity mapping imaging technique. Photofragment images of H+ due to the dissociation mechanism that follows the 2-photon excitation into the (E,F; ν = 0, J = 0) electronic state show a strong dependence on laser intensity, which is attributed to the high polarizability anisotropy of the H2 (E,F) state. We observe a marked structure in the angular distribution, which we explain as the interference between the prepared J = 0 and Stark-mixed J = 2 rovibrational states of H2, as the laser intensity increases. Quantification of these effects allows us to extract the polarizability anisotropy of the H2 (E,F J = 0) state yielding a value of 312 ± 82 a.u. (46 Å3). By comparison, CS2 has 10 Å3, I2 has 7 Å3, and hydrochlorothiazide (C7H8ClN3O4S2) has about 25 Å3 meaning that we have created the most easily aligned molecule ever measured, by creating a mixed superposition state that is highly anisotropic in its polarizability.

  3. Free-field propagation of high intensity noise. [supersonic jets

    NASA Technical Reports Server (NTRS)

    Mcdaniel, O. H.; Roth, S. D.; Welz, J. P.

    1981-01-01

    Research on high intensity (finite amplitude) acoustic waves shows that nonlinear distortion effects generally result in a shift of energy to higher frequencies. The higher intensities associated with supersonic jets would therefore indicate that high frequency enhancement of the spectrum should occur, resulting in the differences observed between subsonic and supersonic jets. A 10,000 acoustic watt source installed in an anechoic chamber generates sound levels such that acoustic shocks are readily observable. Dual frequency excitation of the source produces a strong parametric effect with a difference frequency comparable in level to the primary frequency. The test set up and recording equipment being used to determine the finite amplitude noise representative of an actual supersonic jet are described as well as the development of a computer program based on Burger's equation. The spectra of 1/2 octave band, 1 kHz sine wave, and dual frequency input and output are presented in graphs along with waveforms at Z = .025, 0.1, and 1.0.

  4. Free-field propagation of high intensity noise

    NASA Technical Reports Server (NTRS)

    Welz, Joseph P.; Mcdaniel, Oliver H.

    1990-01-01

    Observed spectral data from supersonic jet aircraft are known to contain much more high frequency energy than can be explained by linear acoustic propagation theory. It is believed that the high frequency energy is an effect of nonlinear distortion due to the extremely high acoustic levels generated by the jet engines. The objective, to measure acoustic waveform distortion for spherically diverging high intensity noise, was reached by using an electropneumatic acoustic source capable of generating sound pressure levels in the range of 140 to 160 decibels (re 20 micro Pa). The noise spectrum was shaped to represent the spectra generated by jet engines. Two microphones were used to capture the acoustic pressure waveform at different points along the propagation path in order to provide a direct measure of the waveform distortion as well as spectral distortion. A secondary objective was to determine that the observed distortion is an acoustic effect. To do this an existing computer prediction code that deals with nonlinear acoustic propagation was used on data representative of the measured data. The results clearly demonstrate that high intensity jet noise does shift the energy in the spectrum to the higher frequencies along the propagation path. In addition, the data from the computer model are in good agreement with the measurements, thus demonstrating that the waveform distortion can be accounted for with nonlinear acoustic theory.

  5. Computer Analysis of Electromagnetic Field Exposure Hazard for Space Station Astronauts during Extravehicular Activity

    NASA Technical Reports Server (NTRS)

    Hwu, Shian U.; Kelley, James S.; Panneton, Robert B.; Arndt, G. Dickey

    1995-01-01

    In order to estimate the RF radiation hazards to astronauts and electronics equipment due to various Space Station transmitters, the electric fields around the various Space Station antennas are computed using the rigorous Computational Electromagnetics (CEM) techniques. The Method of Moments (MoM) was applied to the UHF and S-band low gain antennas. The Aperture Integration (AI) method and the Geometrical Theory of Diffraction (GTD) method were used to compute the electric field intensities for the S- and Ku-band high gain antennas. As a result of this study, The regions in which the electric fields exceed the specified exposure levels for the Extravehicular Mobility Unit (EMU) electronics equipment and Extravehicular Activity (EVA) astronaut are identified for various Space Station transmitters.

  6. Effects of low intensity static electromagnetic radiofrequency fields on leiomyosarcoma and smooth muscle cell lines.

    PubMed

    Karkabounas, Spyridon; Havelas, Konstantinos; Kostoula, Olga K; Vezyraki, Patra; Avdikos, Antonios; Binolis, Jayne; Hatziavazis, George; Metsios, Apostolos; Verginadis, Ioannis; Evangelou, Angelos

    2006-01-01

    In this study we investigated the effects of low intensity static radiofrequency electromagnetic field (EMF) causing no thermal effects, on leiomyosarcoma cells (LSC), isolated from tumors of fifteen Wistar rats induced via a 3,4-benzopyrene injection. Electromagnetic resonance frequencies measurements and exposure of cells to static EMF were performed by a device called multi channel dynamic exciter 100 V1 (MCDE). The LSC were exposed to electromagnetic resonance radiofrequencies (ERF) between 10 kHz to 120 kHz, for 45 min. During a 24h period, after the exposure of the LSC to ERF, there was no inhibition of cells proliferation. In contrast, at the end of a 48 h incubation period, LSC proliferation dramatically decreased by more than 98% (P<0.001). At that time, the survived LSC were only 2% of the total cell population exposed to ERF, and under the same culture conditions showed significant decrease of proliferation. These cells were exposed once again to ERF for 45 min (totally 4 sessions of exposure, of 45 min duration each) and tested using a flow cytometer. Experiments as above were repeated five times. It was found that 45% of these double exposed to ERF, LSC (EMF cells) were apoptotic and only a small percentage 2%, underwent mitosis. In order to determinate their metastatic potential, these EMF cells were also counted and tested by an aggregometer for their ability to aggregate platelets and found to maintain this ability., since they showed no difference in platelet aggregation ability compared to the LSC not exposed to ERF (control cells). In conclusion, exposure of LSC to specific ERF, decreases their proliferation rate and induces cell apoptosis. Also, the LSC that survived after exposed to ERF, had a lower proliferation rate compared to the LSC controls (P<0.05) but did not loose their potential for metastases (platelet aggregation ability). The non-malignant SMC were not affected by the EMF exposure (P<0.4). The specific ERF generated from the MCDE

  7. Coupled near-field and far-field exposure assessment framework for chemicals in consumer products.

    PubMed

    Fantke, Peter; Ernstoff, Alexi S; Huang, Lei; Csiszar, Susan A; Jolliet, Olivier

    2016-09-01

    Humans can be exposed to chemicals in consumer products through product use and environmental emissions over the product life cycle. Exposure pathways are often complex, where chemicals can transfer directly from products to humans during use or exchange between various indoor and outdoor compartments until sub-fractions reach humans. To consistently evaluate exposure pathways along product life cycles, a flexible mass balance-based assessment framework is presented structuring multimedia chemical transfers in a matrix of direct inter-compartmental transfer fractions. By matrix inversion, we quantify cumulative multimedia transfer fractions and exposure pathway-specific product intake fractions defined as chemical mass taken in by humans per unit mass of chemical in a product. Combining product intake fractions with chemical mass in the product yields intake estimates for use in life cycle impact assessment and chemical alternatives assessment, or daily intake doses for use in risk-based assessment and high-throughput screening. Two illustrative examples of chemicals used in personal care products and flooring materials demonstrate how this matrix-based framework offers a consistent and efficient way to rapidly compare exposure pathways for adult and child users and for the general population. This framework constitutes a user-friendly approach to develop, compare and interpret multiple human exposure scenarios in a coupled system of near-field ('user' environment), far-field and human intake compartments, and helps understand the contribution of individual pathways to overall human exposure in various product application contexts to inform decisions in different science-policy fields for which exposure quantification is relevant. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. OLD-FIELD SUCCESSIONAL DYNAMICS FOLLOWING INTENSIVE HERBIVORY

    EPA Science Inventory

    Community composition and successional patterns can be altered by disturbance and exotic species invasions. Our objective was to describe vegetation dynamics following cessation of severe disturbance, which was heavy grazing by cattle, in an old-field grassland subject to invasi...

  9. OLD-FIELD SUCCESSIONAL DYNAMICS FOLLOWING INTENSIVE HERBIVORY

    EPA Science Inventory

    Community composition and successional patterns can be altered by disturbance and exotic species invasions. Our objective was to describe vegetation dynamics following cessation of severe disturbance, which was heavy grazing by cattle, in an old-field grassland subject to invasi...

  10. Generation of superhot electrons by intense field structures

    SciTech Connect

    Salomaa, R. R. E.; Karttunen, S. J.; Paettikangas, T. J. H.; Mulser, P.; Schneider, W.

    1998-02-20

    Strong, localized electrostatic fields created in laser plasma interactions act as a source of hot electrons. We have derived analytical formulas based on adiabatic invariants for explaining of the main characteristics of the electron spectra found in test particle calculations and in full wave-particle simulations. The electrons are treated relativistically. Simple models for phenomenological description of nonlinear wave damping are discussed.

  11. Multifractal dimension and lacunarity of yolk sac vasculature after exposure to magnetic field.

    PubMed

    Costa, Edbhergue Ventura Lola; Nogueira, Romildo de Albuquerque

    2015-05-01

    Several studies have reported about the effects of magnetic fields (MFs) on vascular tissue. Extremely low frequency magnetic fields (ELF-MFs) can promote either inhibition or stimulation of vasculogenesis and angiogenesis, depending upon the intensity and time of exposure to the MF. To investigate the possible effects of ELF-MF on vascular processes, it is necessary to employ methods that allow parameterization of the vascular network. Vascular network is a structure with fractal geometry; therefore, fractal methods have been used to evaluate its morphometric complexity. Here, we used the lacunarity parameter (complementary method of fractal analysis) and multifractal analyses to investigate angiogenesis and vasculogenesis in the embryonic yolk sac membrane (YSM) of Japanese quails (Coturnix japonica) with and without exposure to an external MF of 1 mT and 60 Hz. Lacunarity results showed that the vascular density was lower for the group exposed to the magnetic field for 9 h/day. In addition, multifractal analysis showed reduced vascularization in the experimental groups (6 h/day and 9 h/day of exposure to MF). Furthermore, multifractal analysis showed difference between the groups exposed for 12 and 24 h/day. Using multifractal methods (generalized dimensions and singularity spectrum), it was possible to characterize the vascular network of the quail embryo YSM as a multifractal object, therefore proving this method to be a more appropriate application than the traditional monofractal methods. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. [Cellular radio systems. Problems faced in assessing exposure to electromagnetic fields].

    PubMed

    Zmyślony, M

    2000-01-01

    Over twenty years of its existence, cellular radio systems have become one of the major sources of human exposure to electromagnetic field (EMF) of high frequency. With the increasing number of cellular phones, the interest in health effects of exposure to EMF emitted by them continues to grow. At present, there is a general opinion that thermal effect (change of electromagnetic energy into thermal energy) is an essential mechanism of possible biological effects. The majority of world standards for exposure to EMF are based on this effect. The author presents Polish standards and those of the International Commission on Nonionizing Radiation Protection (ICNIRP) for EMF of frequencies used in cellular radio systems, both basic that limits SAR (Specific Absorption Rate), and derived that limits the power density, as well as intensity of electric and magnetic fields. Attention was also turned to the problems concerning the application of cellular phones and those resulting from the character of the field emitted by them to which their users are exposed. Bearing in mind the results of the laboratory analyses of SAR values occurring in the user's head, and measurements of power density in the vicinity of the base station antennas, it can be stated that, in view of binding and recommended standards, cellular phones do not present any hazard to their users (private or professional). However, it should be stressed that standards adopted protect the user's head against the thermal effect, whereas the question on whether they also protect against non-thermal effects still remains without answer.

  13. Odor frequency and odor annoyance. Part I: assessment of frequency, intensity and hedonic tone of environmental odors in the field.

    PubMed

    Sucker, Kirsten; Both, Ralf; Bischoff, Michael; Guski, Rainer; Winneke, Gerhard

    2008-05-01

    Odors can be evaluated as being pleasant or unpleasant (hedonic tone), but this differentiation was not incorporated into environmental odor regulation. In order to study the hedonic-induced modification of dose-response associations for community odor annoyance a pertinent field study was conducted. This paper covers the first step, namely the development and validation of a standardized human observation strategy for the direct quantification of the frequency, intensity, and hedonic tone of environmental odors in the field. Grids with equidistant observation points were located around six industrial odor sources, two with pleasant (sweets, rusk bakery), two with neutral (textile production, seed oil production), and two with unpleasant odor emissions (fat refinery, cast iron production). These points were visited by trained observers, screened for normal olfaction and reliable performance, in a systematic fashion for an observation time of 10 min duration. Exposure-related information from the observers in terms of frequency, intensity (six-point scale) and hedonic tone (nine-point scale) were compared to that of 1,456 residents using the same rating scales. Residents evaluated the industrial odors more intense and more unpleasant than the panelists. Furthermore, for the residents only negative relations between odor intensity and hedonic tone were found while for the observer pleasant odor became more pleasant with increasing intensity. Instead of three classes of industrial odors, namely pleasant, neutral and unpleasant, the responses allowed only for two odor classes, namely pleasant and not pleasant, the latter also covering the neutral category. The developed methodology has been shown to yield valid information about odor exposure in the field. With regard to different application settings the discrepancies between external observers and affected residents are discussed in terms of different information processing strategies, namely stimulus-based (bottom

  14. Electron Production and Collective Field Generation in Intense Particle Beams

    SciTech Connect

    Molvik, A W; Vay, J; Cohen, R; Friedman, A; Lee, E; Verboncoeur, J; Covo, M K

    2006-02-09

    Electron cloud effects (ECEs) are increasingly recognized as important, but incompletely understood, dynamical phenomena, which can severely limit the performance of present electron colliders, the next generation of high-intensity rings, such as PEP-II upgrade, LHC, and the SNS, the SIS 100/200, or future high-intensity heavy ion accelerators such as envisioned in Heavy Ion Inertial Fusion (HIF). Deleterious effects include ion-electron instabilities, emittance growth, particle loss, increase in vacuum pressure, added heat load at the vacuum chamber walls, and interference with certain beam diagnostics. Extrapolation of present experience to significantly higher beam intensities is uncertain given the present level of understanding. With coordinated LDRD projects at LLNL and LBNL, we undertook a comprehensive R&D program including experiments, theory and simulations to better understand the phenomena, establish the essential parameters, and develop mitigating mechanisms. This LDRD project laid the essential groundwork for such a program. We developed insights into the essential processes, modeled the relevant physics, and implemented these models in computational production tools that can be used for self-consistent study of the effect on ion beams. We validated the models and tools through comparison with experimental data, including data from new diagnostics that we developed as part of this work and validated on the High-Current Experiment (HCX) at LBNL. We applied these models to High-Energy Physics (HEP) and other advanced accelerators. This project was highly successful, as evidenced by the two paragraphs above, and six paragraphs following that are taken from our 2003 proposal with minor editing that mostly consisted of changing the tense. Further benchmarks of outstanding performance are: we had 13 publications with 8 of them in refereed journals, our work was recognized by the accelerator and plasma physics communities by 8 invited papers and we have 5

  15. Mechanism of action of moderate-intensity static magnetic fields on biological systems.

    PubMed

    Rosen, Arthur D

    2003-01-01

    There is substantial evidence indicating that moderate-intensity static magnetic fields (SMF) are capable of influencing a number of biological systems, particularly those whose function is closely linked to the properties of membrane channels. Most of the reported moderate SMF effects may be explained on the basis of alterations in membrane calcium ion flux. The mechanism suggested to explain these effects is based on the diamagnetic anisitropic properties of membrane phospholipids. It is proposed that reorientation of these molecules during moderate SMF exposure will result in the deformation of imbedded ion channels, thereby altering their activation kinetics. Channel inactivation would not be expected to be influenced by these fields because this mechanism is not located within the intramembraneous portion of the channel. Patch-clamp studies of calcium channels have provided support for this hypothesis, as well as demonstrating a temperature dependency that is understandable on the basis of the membrane thermotropic phase transition. Additional studies have demonstrated that sodium channels are similarly affected by SMFs, although to a lesser degree. These findings support the view that moderate SMF effects on biological membranes represent a general phenomenon, with some channels being more susceptible than others to membrane deformation.

  16. Non-Hodgkin's lymphoma among electric utility workers in Ontario: the evaluation of alternate indices of exposure to 60 Hz electric and magnetic fields.

    PubMed

    Villeneuve, P J; Agnew, D A; Miller, A B; Corey, P N

    2000-04-01

    To examine associations between non-Hodgkin's lymphoma (NHL) and exposures to 60 Hz magnetic and electric fields in electric utility workers with a series of indices that capture a variety of aspects of field strength. The study population consisted of 51 cases of NHL and 203 individually matched controls identified from within a cohort of male electric utility workers in Ontario. Odds ratios were calculated for several exposure indices with conditional logistic regression models. Aspects of exposure to electric and magnetic fields that were modelled included: the percentage of time spent above selected threshold field intensities, mean transitions in field strength, SD, and the arithmetic and geometric mean field intensities. For the most part, there was a lack of an association between exposure indices of magnetic fields and the incidence of NHL. Subjects in the upper tertile of percentage of time spent above electric field intensities of 10 and 40 V/m had odds ratios of 3.05 (95% confidence interval (95% CI) 1. 07 to 8.80) and 3.57 (1.30 to 9.80), respectively, when compared with those in the lowest tertile. Moreover, the percentages of time spent above these electric field thresholds were significant predictors of case status over and above the association explained by duration of employment and the arithmetic or geometric mean exposure. These data suggest that exposures above electric field threshold intensities of 10 and 40 V/m are important predictors of NHL. Consequently, the findings support the hypothesis that electric fields may play a promoting part in the aetiology of this cancer. Further occupational studies that include assessment of exposure to electric fields and measures of field strength above similar threshold cut off points are needed to confirm these findings.

  17. Comparison of electric field exposure measurement methods under power lines.

    PubMed

    Korpinen, Leena; Kuisti, Harri; Tarao, Hiroo; Pääkkönen, Rauno; Elovaara, Jarmo

    2014-01-01

    The object of the study was to investigate extremely low frequency (ELF) electric field exposure measurement methods under power lines. The authors compared two different methods under power lines: in Method A, the sensor was placed on a tripod; and Method B required the measurer to hold the meter horizontally so that the distance from him/her was at least 1.5 m. The study includes 20 measurements in three places under 400 kV power lines. The authors used two commercial three-axis meters, EFA-3 and EFA-300. In statistical analyses, they did not find significant differences between Methods A and B. However, in the future, it is important to take into account that measurement methods can, in some cases, influence ELF electric field measurement results, and it is important to report the methods used so that it is possible to repeat the measurements.

  18. Fatal asbestosis 50 years after brief high intensity exposure in a vermiculite expansion plant.

    PubMed

    Wright, Robert S; Abraham, Jerrold L; Harber, Philip; Burnett, Bryan R; Morris, Peter; West, Phil

    2002-04-15

    The authors report the case of a 65-year-old accountant whose only asbestos exposure was during a summer job 50 years earlier in a California vermiculite expansion plant. Vermiculite is a silicate material that is useful in building and agriculture as a filler and insulating agent. He developed extensive fibrocalcific pleural plaques and end-stage pulmonary fibrosis, with rapidly progressive respiratory failure. Careful occupational and environmental history revealed no other source of asbestos exposure, and the initial clinical diagnosis was idiopathic pulmonary fibrosis; open lung biopsy shortly before his death confirmed asbestosis. Electron microscopic lung fiber burden analysis revealed over 8,000,000 asbestos fibers per gram dry lung, 68% of which were tremolite asbestos. Additional asbestiform fibers of composition not matching any of the standard asbestos varieties were also present at over 5,000,000 fibers per gram dry lung. Comparison analysis of a sample of Libby, Montana, vermiculite showed a similar mix of asbestiform fibers including tremolite asbestos. This case analysis raises several concerns: risks of vermiculite induced disease among former workers of the more than 200 expansion plants throughout the United States; health effects of brief but very high-intensity exposures to asbestos; and possible health effects in end-users of consumer products containing vermiculite.

  19. Pain-associated stressor exposure and neuroendocrine values for premature infants in neonatal intensive care.

    PubMed

    Rohan, Annie J

    2016-01-01

    Recurrent stress during neonatal intensive care taxes the adaptive capacity of the premature infant and may be a risk factor for suboptimal developmental outcomes. This research used a descriptive, cross-sectional design and a life course perspective to examine the relationship between resting adrenocorticoid values at 37 postmenstrual weeks of age and cumulative pain-associated stressor exposure in prematurely born infants. Subjects were 59 infants born at under 35 completed weeks of gestation, who were at least 2 weeks of age, and who had been cared for in the NICU since birth. No significant relationships were identified between cortisol values and any of the study variables (number of skin breaking procedures, hours of assisted ventilation, gestational age at birth, exposure to antenatal steroids, history of severe academia, birthweight, days of age to attain birthweight, weight at testing, days of age at testing, recent pain-associated procedures, and 17-OHP value). A significant negative correlation (Spearman rank, one-tailed) between the number of skin-breaking procedures and 17-OHP values was identified (r = -.232, p = .039). Recurrent pain-associated stressor exposure may be a more important factor in explaining the variance of 17-OHP values at 37 postmenstrual weeks of age than birthweight, gestational age, or chronological age.

  20. Ultra-High Intensity Magnetic Field Generation in Dense Plasma

    SciTech Connect

    Fisch, Nathaniel J.

    2014-01-08

    The main objective of this grant proposal was to explore the efficient generation of intense currents. Whereas the efficient generation of electric current in low-­energy-­density plasma has occupied the attention of the magnetic fusion community for several decades, scant attention has been paid to carrying over to high-­energy-­density plasma the ideas for steady-­state current drive developed for low-­energy-­density plasma, or, for that matter, to inventing new methodologies for generating electric current in high-­energy-­density plasma. What we proposed to do was to identify new mechanisms to accomplish current generation, and to assess the operation, physics, and engineering basis of new forms of current drive in regimes appropriate for new fusion concepts.

  1. Effects of low intensity static magnetic field on FTIR spectra and ROS production in SH-SY5Y neuronal-like cells.

    PubMed

    Calabrò, Emanuele; Condello, Salvatore; Currò, Monica; Ferlazzo, Nadia; Caccamo, Daniela; Magazù, Salvatore; Ientile, Riccardo

    2013-12-01

    Biological effects of man-made electromagnetic fields (EMFs) have been studied so far by experimental approaches exposing animals and cell cultures to EMFs. However, the evidence for cell toxicity induced by static magnetic field (SMF) is still uncertain. We investigated the effects produced by the exposure of human SH-SY5Y neuronal-like cells to a uniform magnetic field at intensities of 2.2 mT, which is less than the recommended public exposure limits set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). A decrease of membrane mitochondrial potential up to 30% was measured after 24 h of exposure to SMF in SH-SY5Y cells, and this effect was associated with reactive oxygen species production increase. Fourier transform infrared spectroscopy (FTIR) analysis showed that exposure to a static magnetic intensity around 2.2 mT changed the secondary structure of cellular proteins and lipid components. The vibration bands relative to the methylene group increased significantly after 4 h of exposure, whereas further exposure up to 24 h produced evident shifts of amide I and II modes and a relative increase in β-sheet contents with respect to α-helix components. Our study demonstrated that a moderate SMF causes alteration in cell homeostasis, as indicated by FTIR spectroscopy observations of changes in protein structures that are part of cell response to magnetic field exposure.

  2. Comparison of oro-sensory exposure duration and intensity manipulations on satiation.

    PubMed

    Lasschuijt, M P; Mars, M; Stieger, M; Miquel-Kergoat, S; de Graaf, C; Smeets, Pam

    2017-02-04

    Oro-sensory exposure (OSE) is an important factor in the regulation of food intake with increasing OSE leading to lower food intake. Oral processing time and taste intensity both play an important role in OSE but their individual contribution to satiation is unknown. We aimed to determine the independent and combined effects of oral processing time and taste intensity on satiation. Fifty eight participants (23±9y, BMI 22±2kg/m(2)) participated in a 2×2 factorial randomized crossover study in which they consumed one of four gel-based model foods until satiation during four sessions. Model foods were offered ad libitum and differed in texture (soft or hard texture, yielding shorter and longer oral processing time) and sweetness (low or high intensity). Model foods were isocaloric and were matched for flavor and palatability. Outcome measures were intake of the model food and the microstructure of eating behavior, such as number of chews and eating rate. There was an overall significant effect of texture (p<0.001) but not sweetness (p=0.33) on intake with a 29.2% higher intake of the soft model foods compared to the hard model foods. After correction for palatability the difference in intake between the soft and hard model foods was 21.5% (p<0.001). The number of chews was significantly lower for the soft (10.1±6.2) than for the hard (26.9±6.2) model foods (p<0.001), which resulted in a significantly lower eating rate (soft, 26.3±10.2 and hard, 15.3±7.1g/min, p<0.001). These results show that increasing texture hardness of gel model foods decreases food intake independent of sweet taste intensity. The higher number of chews and faster eating rate may cause this effect. In conclusion, oro-sensory exposure duration rather than taste intensity appears to be the main determinant of food intake.

  3. Measured Head CT/CTA Skin Dose and Intensive Care Unit Patient Cumulative Exposure.

    PubMed

    Nawfel, R D; Young, G S

    2017-03-01

    Estimates of cumulative CT/CTA radiation dose based on volumetric CT dose index have raised concern that neurological intensive care unit patient exposures may reach thresholds for deterministic skin injury. Because the accuracy of volumetric CT dose index for this purpose in unknown, we set out to directly measure head CT and CTA peak skin dose, assess the relationship of volumetric CT dose index to measured peak skin dose, and determine whether multiple CT/CTA exposures in typical patients in the neurological intensive care unit produce cumulative doses approaching or exceeding single-dose deterministic thresholds for skin injury. In a prospective study from 2011-2013, nanoDot optical stimulated luminescence dosimeters were used to measure head CT/CTA peak skin dose in 52 patients (28 female, 24 male; mean age, 63 years) divided equally between 2 CT scanners. Volumetric CT dose index and dose-length product were recorded for each examination. Peak skin dose was also measured on an acrylic skull phantom in each scanner. A 2-tailed, unpaired t test was used to compare mean patient skin doses between the 2 scanners. The measured peak skin doses were then used to calculate cumulative peak skin dose in 4 typical patients in intensive care units who received multiple CT/CTA scans. Head CT/CTA peak skin dose agreed between scanners in patients and phantoms: (scanner 1 CT/CTA: patients, 39.2 ± 3.7 mGy and 98.9 ± 5.3 mGy, respectively, versus phantom, 40.0 mGy and 105.4 mGy, respectively; scanner 2 CT/CTA: patients, 42.9 ± 9.4 mGy and 98.8 ± 7.4 mGy, respectively, versus phantom, 37.6 mGy and 95.2 mGy, respectively). Volumetric CT dose index overestimated peak skin dose by a factor of 1.4-1.9 depending on examination and CT scanner. Cumulative doses in 4 patients in the intensive care unit estimated from measured CT/CTA peak skin dose ranged from 1.9-4.5 Gy. Directly measured radiation skin doses from head CT/CTA patient examinations are substantially lower than

  4. Neuronal cellular responses to extremely low frequency electromagnetic field exposure: implications regarding oxidative stress and neurodegeneration.

    PubMed

    Reale, Marcella; Kamal, Mohammad A; Patruno, Antonia; Costantini, Erica; D'Angelo, Chiara; Pesce, Miko; Greig, Nigel H

    2014-01-01

    Neurodegenerative diseases comprise both hereditary and sporadic conditions characterized by an identifying progressive nervous system dysfunction and distinctive neuopathophysiology. The majority are of non-familial etiology and hence environmental factors and lifestyle play key roles in their pathogenesis. The extensive use of and ever increasing worldwide demand for electricity has stimulated societal and scientific interest on the environmental exposure to low frequency electromagnetic fields (EMFs) on human health. Epidemiological studies suggest a positive association between 50/60-Hz power transmission fields and leukemia or lymphoma development. Consequent to the association between EMFs and induction of oxidative stress, concerns relating to development of neurodegenerative diseases, such as Alzheimer disease (AD), have been voiced as the brain consumes the greatest fraction of oxygen and is particularly vulnerable to oxidative stress. Exposure to extremely low frequency (ELF)-EMFs are reported to alter animal behavior and modulate biological variables, including gene expression, regulation of cell survival, promotion of cellular differentiation, and changes in cerebral blood flow in aged AD transgenic mice. Alterations in inflammatory responses have also been reported, but how these actions impact human health remains unknown. We hence evaluated the effects of an electromagnetic wave (magnetic field intensity 1 mT; frequency, 50-Hz) on a well-characterized immortalized neuronal cell model, human SH-SY5Y cells. ELF-EMF exposure elevated the expession of NOS and O2(-), which were countered by compensatory changes in antioxidant catylase (CAT) activity and enzymatic kinetic parameters related to CYP-450 and CAT activity. Actions of ELF-EMFs on cytokine gene expression were additionally evaluated and found rapidly modified. Confronted with co-exposure to H2O2-induced oxidative stress, ELF-EMF proved not as well counteracted and resulted in a decline in CAT

  5. Behavioral and neural discrimination of speech sounds after moderate or intense noise exposure in rats.

    PubMed

    Reed, Amanda C; Centanni, Tracy M; Borland, Michael S; Matney, Chanel J; Engineer, Crystal T; Kilgard, Michael P

    2014-01-01

    Hearing loss is a commonly experienced disability in a variety of populations including veterans and the elderly and can often cause significant impairment in the ability to understand spoken language. In this study, we tested the hypothesis that neural and behavioral responses to speech will be differentially impaired in an animal model after two forms of hearing loss. Sixteen female Sprague-Dawley rats were exposed to one of two types of broadband noise which was either moderate or intense. In nine of these rats, auditory cortex recordings were taken 4 weeks after noise exposure (NE). The other seven were pretrained on a speech sound discrimination task prior to NE and were then tested on the same task after hearing loss. Following intense NE, rats had few neural responses to speech stimuli. These rats were able to detect speech sounds but were no longer able to discriminate between speech sounds. Following moderate NE, rats had reorganized cortical maps and altered neural responses to speech stimuli but were still able to accurately discriminate between similar speech sounds during behavioral testing. These results suggest that rats are able to adjust to the neural changes after moderate NE and discriminate speech sounds, but they are not able to recover behavioral abilities after intense NE. Animal models could help clarify the adaptive and pathological neural changes that contribute to speech processing in hearing-impaired populations and could be used to test potential behavioral and pharmacological therapies.

  6. Behavioral and Neural Discrimination of Speech Sounds After Moderate or Intense Noise Exposure in Rats

    PubMed Central

    Reed, Amanda C.; Centanni, Tracy M.; Borland, Michael S.; Matney, Chanel J.; Engineer, Crystal T.; Kilgard, Michael P.

    2015-01-01

    Objectives Hearing loss is a commonly experienced disability in a variety of populations including veterans and the elderly and can often cause significant impairment in the ability to understand spoken language. In this study, we tested the hypothesis that neural and behavioral responses to speech will be differentially impaired in an animal model after two forms of hearing loss. Design Sixteen female Sprague–Dawley rats were exposed to one of two types of broadband noise which was either moderate or intense. In nine of these rats, auditory cortex recordings were taken 4 weeks after noise exposure (NE). The other seven were pretrained on a speech sound discrimination task prior to NE and were then tested on the same task after hearing loss. Results Following intense NE, rats had few neural responses to speech stimuli. These rats were able to detect speech sounds but were no longer able to discriminate between speech sounds. Following moderate NE, rats had reorganized cortical maps and altered neural responses to speech stimuli but were still able to accurately discriminate between similar speech sounds during behavioral testing. Conclusions These results suggest that rats are able to adjust to the neural changes after moderate NE and discriminate speech sounds, but they are not able to recover behavioral abilities after intense NE. Animal models could help clarify the adaptive and pathological neural changes that contribute to speech processing in hearing-impaired populations and could be used to test potential behavioral and pharmacological therapies. PMID:25072238

  7. Inactivation of Saccharomyces cerevisiae suspended in orange juice using high-intensity pulsed electric fields.

    PubMed

    Elez-Martínez, Pedro; Escolà-Hernández, Joan; Soliva-Fortuny, Robert C; Martín-Belloso, Olga

    2004-11-01

    Saccharomyces cerevisiae is often associated with the spoilage of fruit juices. The purpose of this study was to evaluate the effect of high-intensity pulsed electric field (HIPEF) treatment on the survival of S. cerevisiae suspended in orange juice. Commercial heat-sterilized orange juice was inoculated with S. cerevisiae (CECT 1319) (10(8) CFU/ml) and then treated by HIPEFs. The effects of HIPEF parameters (electric field strength, treatment time, pulse polarity, frequency, and pulse width) were evaluated and compared to those of heat pasteurization (90 degrees C/min). In all of the HIPEF experiments, the temperature was kept below 39 degrees C. S. cerevisiae cell damage induced by HIPEF treatment was observed by electron microscopy. HIPEF treatment was effective for the inactivation of S. cerevisiae in orange juice at pasteurization levels. A maximum inactivation of a 5.1-log (CFU per milliliter) reduction was achieved after exposure of S. cerevisiae to HIPEFs for 1,000 micros (4-micros pulse width) at 35 kV/cm and 200 Hz in bipolar mode. Inactivation increased as both the field strength and treatment time increased. For the same electric field strength and treatment time, inactivation decreased when the frequency and pulse width were increased. Electric pulses applied in the bipolar mode were more effective than those in the monopolar mode for destroying S. cerevisiae. HIPEF processing inactivated S. cerevisiae in orange juice, and the extent of inactivation was similar to that obtained during thermal pasteurization. HIPEF treatments caused membrane damage and had a profound effect on the intracellular organization of S. cerevisiae.

  8. Thermal relaxation of adsorbed atoms in an intense laser field

    NASA Astrophysics Data System (ADS)

    Arnoldus, Henk F.; van Smaalen, Sander; George, Thomas F.

    1986-11-01

    Adsorbed atoms on the surface of a harmonic lattice are immersed in a strong laser field. The optical Bloch equations are derived, which include the thermal relaxation and the coherent excitation of the adbond. This is accomplished by a transformation to dressed states, which diagonalizes the interaction with the laser. The single-phonon couplings are then understood as transitions between dressed states. The radiative contributions for arbitrarily strong fields are obtained in the master equation, and it is shown that the coherences with respect to the dressed states decay exponentially, due to the phonon relaxation. General properties of the competing phonon-induced redistribution and optical excitation of the level populations are presented, and exemplified by an explicit elaboration of a three-level system. The results are amenable to analytical evaluation once the interaction potential is prescribed, and extensions of the approach to include multiphonon processes are straightforward.

  9. Effect Modification of the Association of Cumulative Exposure and Cancer Risk by Intensity of Exposure and Time Since Exposure Cessation: A Flexible Method Applied to Cigarette Smoking and Lung Cancer in the SYNERGY Study

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-02-01

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

  11. [Patient exposure to electromagnetic fields in magnetic resonance scanners: a review].

    PubMed

    Guibelalde del Castillo, E

    2013-12-01

    The use of non-ionizing electromagnetic fields in the low frequency end of the electromagnetic spectrum and static fields, radiofrequencies (RF), and microwaves is fundamental both in modern communication systems and in diagnostic medical imaging techniques like magnetic resonance imaging (MRI). The proliferation of these applications in recent decades has led to intense activity in developing regulations to guarantee their safety and to the establishment of guidelines and legal recommendations for the public, workers, and patients. In April 2012 it was foreseen that the European Parliament and Council would approve and publish a directive on the minimum health and safety requirements regarding the exposure of workers to the risks arising from electromagnetic fields, which would modify Directive 2004/40/EC. New studies related to the exposure to electromagnetic radiation and its impact on health published in recent years have led to a new postponement, and it is now foreseen that the directive will come into effect in October 2013. One of the most noteworthy aspects of the new version of the directive is the exclusion of the limits of occupational exposure to electromagnetic fields in the clinical use of MRI. In exchange for this exception, physicians and experts in protection against non-ionizing radiation are asked to make additional efforts to train workers exposed to non-ionizing radiation and to establish mechanisms to guarantee the correct application of non-ionizing electromagnetic fields in patients, along similar lines to the principles of justification and optimization established for ionizing radiation. On the basis of the most recently published studies, this article reviews some safety-related aspects to take into account when examining patients with MRI with high magnetic fields. Copyright © 2013 SERAM. Published by Elsevier Espana. All rights reserved.

  12. Extremely low frequency electromagnetic field exposure affects fertilization outcome in swine animal model.

    PubMed

    Bernabò, N; Tettamanti, E; Russo, V; Martelli, A; Turriani, M; Mattoli, M; Barboni, B

    2010-06-01

    Modern society continuously exposes the population to electromagnetic radiation, the effects of which on human health, in particular reproduction, are still unknown. The aim of this research was to assess the effect of acute (1h) exposure of boar spermatozoa to a 50 Hz extremely low frequency electromagnetic field (ELF-EMF) on early fertility outcome. The effect of intensities ranging from 0 to 2 mT on morpho-functional integrity of capacitated spermatozoa was examined in vitro. The oviducts containing or without spermatozoa were then exposed to the minimum in vivo, TD(50,) and maximum intensities determined in vitro, 4h before ovulation. The effects of ELF-EMF on spermatozoa in terms of early embryo development were evaluated after 12h and 6 days. It was found that in vitro ELF-EMF > 0.5 mT induced a progressive acrosome damage, thus compromising the ability of spermatozoa to undergo acrosomal reaction after zona pellucida stimulation and reducing the in vitro fertilization outcome. These effects became evident at 0.75 mT and reached the plateau at 1 mT. Under in vivo conditions, the ELF-EMF intensity of 1 mT was able to compromise sperm function, significantly reducing the fertilization rate. In addition, the exposure of oviducts to fields > or = 0.75 mT in the absence of spermatozoa was able to negatively affect early embryo development. In fact, it was found to cause a slowdown in the embryo cleavage. In conclusion, it was demonstrated how and at which intensities ELF-EMF negatively affect early fertility outcome in a highly predictive animal model.

  13. The effects of intense magnetic fields on Landau levels in a neutron star

    NASA Astrophysics Data System (ADS)

    Gao, Z. F.; Wang, N.; Song, D. L.; Yuan, J. P.; Chou, C.-K.

    2011-08-01

    In this paper, an approximate method of calculating the Fermi energy of electrons ( E F ( e)) in a high-intensity magnetic field, based on the analysis of the distribution of a neutron star magnetic field, has been proposed. In the interior of a neutron star, different forms of intense magnetic field could exist simultaneously and a high electron Fermi energy could be generated by the release of magnetic field energy. The calculation results show that: E F ( e) is related to density ρ, the mean electron number per baryon Y e and magnetic field strength B.

  14. Magnetic field generation during intense laser channelling in underdense plasma

    SciTech Connect

    Smyth, A. G.; Sarri, G.; Doria, D.; Kar, S.; Borghesi, M.; Vranic, M.; Guillaume, E.; Silva, L. O.; Vieira, J.; Heathcote, R.; Norreys, P. A.; Hicks, G.; Najmudin, Z.; Nakamura, H.

    2016-06-15

    Channel formation during the propagation of a high-energy (120 J) and long duration (30 ps) laser pulse through an underdense deuterium plasma has been spatially and temporally resolved via means of a proton imaging technique, with intrinsic resolutions of a few μm and a few ps, respectively. Conclusive proof is provided that strong azimuthally symmetric magnetic fields with a strength of around 0.5 MG are created inside the channel, consistent with the generation of a collimated beam of relativistic electrons. The inferred electron beam characteristics may have implications for the cone-free fast-ignition scheme of inertial confinement fusion.

  15. Electromagnetically induced transparency in an asymmetric double quantum well under non-resonant, intense laser fields

    NASA Astrophysics Data System (ADS)

    Niculescu, E. C.

    2017-02-01

    Electromagnetically induced transparency in an asymmetric double quantum well subjected to a non-resonant, intense laser field is theoretically investigated. We found that the energy levels configuration could be switched between a Λ-type and a ladder-type scheme by varying the non-resonant radiation intensity. This effect is due to the laser-induced electron tunneling between the wells and it allows a substantial flexibility in the manipulation of the optical properties. The dependence of the susceptibilities on the control field Rabi frequency, intensity of the nonresonant laser, and the control field detuning for both configurations are discussed and compared.

  16. Hidden Toxicity in Neonatal Intensive Care Units: Phthalate Exposure in Very Low Birth Weight Infants

    PubMed Central

    Demirel, Atalay; Çoban, Asuman; Yıldırım, Şükran; Doğan, Canan; Sancı, Rukiye; İnce, Zeynep

    2016-01-01

    Objective: To determine exposure to endocrine-disrupting phthalates in preterm infants in neonatal intensive care units (NICU). Methods: Urine samples (n=151) from 36 preterm infants (<32 weeks of gestation and/or <1500 g of birth weight) were collected on the first 3 days of admission to the NICU and biweekly thereafter. Diethylhexyl phthalate contents of indwelling medical devices used in various procedures and the concentrations of phthalate metabolites in the urine samples were analyzed. The relationships between urinary excretion, exposure intensity, postnatal age and birth weight were examined. Results: The mean gestational age and mean birth weight of the study infants were 28.9±1.5 weeks and 1024±262 g, respectively. Diethylhexyl phthalate was detected in umbilical catheters, endotracheal tubes, nasogastric tubes, and nasal cannula. Monoethylhydroxyhexyl phthalate (MEHHP) was the most frequently detected metabolite (81.4%); its concentration increased during the first 4 weeks and then started to decrease but never disappeared. Patients who did not need indwelling catheters (except nasogastric tubes) after 2 weeks were classified as group 1 and those who continued to have indwelling catheters as group 2. Although not of statistical significance, MEHHP levels decreased in group 1 but continued to stay high in group 2 (in the 4th week, group 1: 65.9 ng/mL and group 2: 255.3 ng/mL). Levels of MEHHP in the first urinary samples were significantly higher in infants with a birth weight <1000 g (<1000 g: 63.2±93.8 ng/mL, ≥1000 g: 10.9±22.9 ng/mL, p=0.001). Conclusion: Phthalate metabolites were detected even in the first urine samples of very low birth weight newborns. Phthalate levels were higher in the first weeks of intensive invasive procedures and in preterm infants with a birth weight less than 1000 g. MEHHP was the most frequently detected metabolite and could be a suitable biomarker for the detection of phthalate exposure in preterm infants. PMID

  17. Light intensity exposure, sleep duration, physical activity, and biomarkers of melatonin among rotating shift nurses.

    PubMed

    Grundy, Anne; Sanchez, Maria; Richardson, Harriet; Tranmer, Joan; Borugian, Marilyn; Graham, Charles H; Aronson, Kristan J

    2009-10-01

    Long-term, night shiftwork has been identified as a potential carcinogenic risk factor. It is hypothesized that increased light at night exposure during shiftwork reduces melatonin production, which is associated with increased cancer risk. Sleep duration has been hypothesized to influence both melatonin levels and cancer risk, and it has been suggested that sleep duration could be used as a proxy for melatonin production. Finally, physical activity has been shown to reduce cancer risk, and laboratory studies indicate it may influence melatonin levels. A cross-sectional study of light exposure, sleep duration, physical activity, and melatonin levels was conducted among 61 female rotating shift nurses (work schedule: two 12 h days, two 12 h nights, five days off). Light intensity was measured using a light-intensity data logger, and sleep duration and physical activity were self-reported in a study diary and questionnaire. Melatonin concentrations were measured from urine and saliva samples. The characteristics of nurses working day and night shifts were similar. Light intensity was significantly higher during sleep for those working at night (p< 0.0001), while urinary melatonin levels following sleep were significantly higher among those working days (p = 0.0003). Mean sleep duration for nurses working during the day (8.27 h) was significantly longer than for those working at night (4.78 h, p< 0.0001). An inverse association (p = 0.002) between light exposure and urinary melatonin levels was observed; however, this was not significant when stratified by shift group. There was no significant correlation between sleep duration and melatonin, and no consistent relationship between physical activity and melatonin. Analysis of salivary melatonin levels indicated that the circadian rhythms of night workers were not altered, meaning peak melatonin production occurred at night. This study indicates that two nights of rotating shift work may not change the timing of

  18. Intensity of the geomagnetic field in Europe for the last 3 ka: Influence of data quality on geomagnetic field modeling

    NASA Astrophysics Data System (ADS)

    Pavón-Carrasco, Francisco Javier; Gómez-Paccard, Miriam; Hervé, Gwenaël.; Osete, María. Luisa; Chauvin, Annick

    2014-06-01

    of the main challenges of paleomagnetic research is to obtain high-resolution geomagnetic field intensity reconstructions. For the last millennia, these reconstructions are mostly based on archeomagnetic data. However, the quality of the intensity data available in the databases is very variable, and the high scatter observed in the records clearly suggests that some of them might not be reliable. In this work we investigate how the geomagnetic field intensity reconstructions and, hence, our present knowledge of the geomagnetic field in the past, are affected by the quality of the data selected for modeling the Earth's magnetic field. For this purpose we rank the European archeointensity data in four quality categories following widely accepted paleomagnetic criteria based on the methodology used during the laboratory treatment of the samples and on the number of specimens retained to calculate the mean intensities. Four geomagnetic field regional models have been implemented by applying the revised spherical cap harmonic analysis to these four groups of input data. Geomagnetic field models strongly depend on the used data set. The model built using all the available data (without any preselection) appears to be the less accurate, indicating some internal inconsistencies of the data set. In addition, some features of this model are clearly dominated by the less reliable archeointensity data, suggesting that such features might not reflect real variations of the past geomagnetic field. On the contrary, the regional model built on selected high-quality intensity data shows a very consistent intensity pattern at the European scale, confirming that the main intensity changes observed in Europe in the recent history of the geomagnetic field occurred at the continental scale.

  19. Human exposure risk to heavy metals through groundwater used for drinking in an intensively irrigated river delta

    NASA Astrophysics Data System (ADS)

    Vetrimurugan, E.; Brindha, K.; Elango, L.; Ndwandwe, Osman Muzi

    2016-09-01

    Drinking water containing heavy metals above the maximum permissible limits cause potential risk to human health. The aim of this study was to determine the groundwater suitability for drinking use based on heavy metal concentration and the associated human exposure risk in an intensively irrigated part of the Cauvery river basin, Tamil Nadu, India. Sixteen heavy metals analysed were in the order of dominance of chromium < zinc < copper < cadmium < cobalt < iron < aluminium < nickel < titanium < zirconium < boron < silver < manganese < lead < lithium < silicon in groundwater. Chromium and zinc were within permissible limits of the Bureau of Indian Standards for drinking water quality, and silver, lead and nickel were above limits in all the groundwater samples. In less than 50 % of the groundwater samples, aluminium, boron, cadmium, copper, iron and manganese exceeded their individual permissible limits. Heavy metal pollution index based on 11 heavy metals indicated that groundwater quality of this area is poor-to-unsuitable. Non-carcinogenic risk for humans due to ingestion of groundwater through drinking water pathway was very high for infants, children and adults. Silver, lead, nickel, cadmium and manganese largely contributed to the health hazard. Sources of heavy metals were identified to be geological and from human activities, i.e., application of fertilizers in agricultural fields, seawater intrusion due to intensive pumping for agriculture and wastewater from industries. Groundwater and surface water in this area pose large threat due to high levels of heavy metals, and it is necessary to avoid this water for drinking due to potential risk of health hazard. This study also demonstrated the application of HPI and human exposure hazard index to study the groundwater quality based on heavy metals' concentration.

  20. Bio-effects and safety of low-intensity, low-frequency ultrasonic exposure.

    PubMed

    Ahmadi, Farzaneh; McLoughlin, Ian V; Chauhan, Sunita; ter-Haar, Gail

    2012-04-01

    Low-frequency (LF) ultrasound (20-100 kHz) has a diverse set of industrial and medical applications. In fact, high power industrial applications of ultrasound mainly occupy this frequency range. This range is also used for various therapeutic medical applications including sonophoresis (ultrasonic transdermal drug delivery), dentistry, eye surgery, body contouring, the breaking of kidney stones and eliminating blood clots. While emerging LF applications such as ultrasonic drug delivery continue to be developed and undergo translation for human use, significant gaps exist in the coverage of safety standards for this frequency range. Accordingly, the need to understand the biological effects of LF ultrasound is becoming more important. This paper presents a broad overview of bio-effects and safety of LF ultrasound as an aid to minimize and control the risk of these effects. Its particular focus is at low intensities where bio-effects are initially observed. To generate a clear perspective of hazards in LF exposure, the mechanisms of bio-effects and the main differences in action at low and high frequencies are investigated and a survey of harmful effects of LF ultrasound at low intensities is presented. Mechanical and thermal indices are widely used in high frequency diagnostic applications as a means of indicating safety of ultrasonic exposure. The direct application of these indices at low frequencies needs careful investigation. In this work, using numerical simulations based on the mathematical and physical rationale behind the indices at high frequencies, it is observed that while thermal index (TI) can be used directly in the LF range, mechanical index (MI) seems to become less reliable at lower frequencies. Accordingly, an improved formulation for the MI is proposed for frequencies below 500 kHz.

  1. High exposure to respirable dust and quartz in a labour-intensive coal mine in Tanzania.

    PubMed

    Mamuya, Simon H D; Bråtveit, Magne; Mwaiselage, Julius; Mashalla, Yohana J S; Moen, Bente E

    2006-03-01

    Labour-intensive mines are numerous in several developing countries, but dust exposure in such mines has not been adequately characterized. The aim of this study was to identify and quantify the determinants of respirable dust and quartz exposure among underground coal mine workers in Tanzania. Personal respirable dust samples (n = 134) were collected from 90 underground workers in June-August 2003 and July-August 2004. The development team had higher exposure to respirable dust and quartz (geometric means 1.80 and 0.073 mg m(-3), respectively) than the mining team (0.47 and 0.013 mg m(-3)), the underground transport team (0.14 and 0.006 mg m(-3)) and the underground maintenance team (0.58 and 0.016 mg m(-3)). The percentages of samples above the threshold limit values (TLVs) of 0.9 mg m(-3) for respirable bituminous coal dust and 0.05 mg m(-3) for respirable quartz, respectively, were higher in the development team (55 and 47%) than in the mining team (20 and 9%). No sample for the underground transport team exceeded the TLV. Drilling in the development was the work task associated with the highest exposure to respirable dust and quartz (17.37 and 0.611 mg m(-3), respectively). Exposure models were constructed using multiple regression model analysis, with log-transformed data on either respirable dust or quartz as the dependent variable and tasks performed as the independent variables. The models for the development section showed that blasting and pneumatic drilling times were major determinants of respirable dust and quartz, explaining 45.2 and 40.7% of the variance, respectively. In the mining team, only blasting significantly determined respirable dust. Immediate actions for improvements are suggested to include implementing effective dust control together with improved training and education programmes for the workers. Dust and quartz in this underground mine should be controlled by giving priority to workers performing drilling and blasting in the

  2. Investigations of Penetration Electric Fields and Low-Latitude Ionospheric Disturbances During Intense Geomagnetic Storms

    DTIC Science & Technology

    2012-09-11

    Rayleigh - Taylor instability process over a large longitudinal range. These plasma bubbles grow and merge to form a wide bubble...Investigations of penetration electric fields and low-latitude ionospheric disturbances during intense geomagnetic storms Principal Investigator: Dr. Sunanda... ionospheric dynamics during intense geomagnetic storms. Summary of Progress: We have

  3. Explosions of water clusters in intense laser fields

    SciTech Connect

    Kumarappan, V.; Krishnamurthy, M.; Mathur, D.

    2003-06-01

    Energetic, highly charged oxygen ions O{sup q+} (q{<=}6), are copiously produced upon laser field-induced disassembly of highly charged water clusters, (H{sub 2}O){sub n} and (D{sub 2}O){sub n}, n{approx}60, that are formed by seeding high-pressure helium or argon with water vapor. Ar{sub n} clusters (n{approx}40 000) formed under similar experimental conditions are found to undergo disassembly in the Coulomb explosion regime, with the energies of Ar{sup q+} ions showing a q{sup 2} dependence. Water clusters, which are argued to be considerably smaller in size, should also disassemble in the same regime, but the energies of fragment O{sup q+} ions are found to depend linearly on q which, according to prevailing wisdom, ought to be a signature of hydrodynamic expansion that is expected of much larger clusters. The implication of these observations on our understanding of the two cluster explosion regimes, Coulomb explosion and hydrodynamic expansion, is discussed. Our results indicate that charge state dependences of ion energy do not constitute an unambiguous experimental signature of cluster explosion regime.

  4. Interference stabilization and UV lasing in a plasma channel formed in gas by intense RF field

    NASA Astrophysics Data System (ADS)

    Bogatskaya, A. V.; Popov, A. M.

    2015-04-01

    The effect of interference stabilization of Rydberg atoms in a high-intensity IR laser field is proposed to create a plasma channel with population inversion for conversion of the input laser energy into the VUV and XUV frequency band.

  5. The geomagnetic field intensity variations in the Iberian Peninsula during the last millennium

    NASA Astrophysics Data System (ADS)

    Nachasova, I. E.; Akimova, S. V.

    2015-09-01

    The pattern of variations in the intensity of the geomagnetic field starting from the middle of the sixth millennium B.C. is reconstructed from the data about the intensity of the ancient geomagnetic field in the region of the Iberian Peninsula provided by the archaeomagnetic studies of ceramics from archaeological monuments. In this time interval, the intensity of the field widely varies from ~30 to ~90 µT. The smooth variation of the field is superimposed by the variations with characteristic times from thousands to hundreds of years. The intensity variations can be subdivided into two groups: rather sharp variations with a characteristic duration of about 200 years and smooth quasi-harmonic fluctuations with a duration of a few hundred years.

  6. Take home lead exposure in children of oil field workers.

    PubMed

    Khan, Fahad

    2011-06-01

    Childhood lead poisoning is a major, preventable environmental health problem. While residential lead-based paint and lead contaminated dust and soil are the most common sources of childhood lead poisoning, children can also be at risk if they live with an adult with a job or hobby that involves exposure to lead. Currently, the Oklahoma Childhood Lead Poisoning Prevention Program (OCLPPP) has a small number of cases of "take home" lead exposure in children of oil field workers. These workers may come in contact with a threading compound, "pipe dope" that can contain large amounts of lead. Workers handling this product may be exposed to lead by not following safety instructions. Additionally workers may not be provided the facilities to shower and change out of the contaminated clothing before leaving the work location. The OCLPPP recommends employers and worksites should consider effective alternative options like lead free biodegradable pipe dopes or dope free connections to prevent workers and their families from adverse health effects associated with lead.

  7. Effects of electromagnetic fields on the nonlinear optical properties of asymmetric double quantum well under intense laser field

    NASA Astrophysics Data System (ADS)

    Yesilgul, U.; Sari, H.; Ungan, F.; Martínez-Orozco, J. C.; Restrepo, R. L.; Mora-Ramos, M. E.; Duque, C. A.; Sökmen, I.

    2017-03-01

    In this study, the effects of electric and magnetic fields on the optical rectification and second and third harmonic generation in asymmetric double quantum well under the intense non-resonant laser field is theoretically investigated. We calculate the optical rectification and second and third harmonic generation within the compact density-matrix approach. The theoretical findings show that the influence of electric, magnetic, and intense laser fields leads to significant changes in the coefficients of nonlinear optical rectification, second and third harmonic generation.

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

    PubMed

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

    2012-11-30

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

  9. Changes in manganese superoxide dismutase expression after exposure of the retina to intense light.

    PubMed

    Yamamoto, M; Lidia, K; Gong, H; Onitsuka, S; Kotani, T; Ohira, A

    1999-02-01

    Manganese superoxide dismutase (Mn-SOD) is a naturally-occurring scavenger of superoxide, one of several reactive oxygen intermediates. To determine if Mn-SOD expression is enhanced as a defensive mechanism against oxidative challenges, such as intense light exposure, rats were exposed to cyclic light (80 lux) for 2 weeks, intense light (1,800 lux) for 24 h, and then again to cyclic light. Experimental and control (exposed to cyclic light only) eyes were enucleated 3 h, 1, 3, 7, and 14 days after light challenge. Protein expression was examined immunohistochemically using rabbit antisera against rat Mn-SOD. There was no significant difference between the light-exposed and the control groups in the thickness of the outer nuclear layers. Both retinal pigment epithelial cells and photoreceptor inner segments in the normal retina were labeled for Mn-SOD. Mn-SOD labeling was lost 3 h and day 1 after light challenge. It was re-expressed in the retinal pigment epithelial cells 3, 7, and 14 days after the light challenge, and in the photoreceptor inner segments after day 14. These results suggest that the retina might have a protective potential against light damage, in which Mn-SOD may play an important role.

  10. Exposure to electromagnetic fields from laptop use of "laptop" computers.

    PubMed

    Bellieni, C V; Pinto, I; Bogi, A; Zoppetti, N; Andreuccetti, D; Buonocore, G

    2012-01-01

    Portable computers are often used at tight contact with the body and therefore are called "laptop." The authors measured electromagnetic fields (EMFs) laptop computers produce and estimated the induced currents in the body, to assess the safety of laptop computers. The authors evaluated 5 commonly used laptop of different brands. They measured EMF exposure produced and, using validated computerized models, the authors exploited the data of one of the laptop computers (LTCs) to estimate the magnetic flux exposure of the user and of the fetus in the womb, when the laptop is used at close contact with the woman's womb. In the LTCs analyzed, EMF values (range 1.8-6 μT) are within International Commission on Non-Ionizing Radiation (NIR) Protection (ICNIRP) guidelines, but are considerably higher than the values recommended by 2 recent guidelines for computer monitors magnetic field emissions, MPR II (Swedish Board for Technical Accreditation) and TCO (Swedish Confederation of Professional Employees), and those considered risky for tumor development. When close to the body, the laptop induces currents that are within 34.2% to 49.8% ICNIRP recommendations, but not negligible, to the adult's body and to the fetus (in pregnant women). On the contrary, the power supply induces strong intracorporal electric current densities in the fetus and in the adult subject, which are respectively 182-263% and 71-483% higher than ICNIRP 98 basic restriction recommended to prevent adverse health effects. Laptop is paradoxically an improper site for the use of a LTC, which consequently should be renamed to not induce customers towards an improper use.

  11. Rats avoid exposure to HVdc electric fields: a dose response study.

    PubMed

    Creim, J A; Lovely, R H; Weigel, R J; Forsythe, W C; Anderson, L E

    1993-01-01

    Rats, given the choice, avoid exposure to alternating current (ac) 60-Hz electric fields at intensities > or = 75 kV/m. This study investigated the generality of this behavior by studying the response of rats when exposed to high voltage direct current (HVdc) electric fields. Three hundred eighty male Long Evans rats were studied in 9 experiments with 40 rats per experiment and in one experiment with 20 rats to determine 1) if rats avoid exposure to HVdc electric fields of varying field strengths, and 2) if avoidance did occur, what role, if any, the concentration of air ions would have on the avoidance behavior. In all experiments a three-compartment glass shuttlebox was used; either the left or right compartment could be exposed to a combination of HVdc electric fields and air ions while the other compartment remained sham-exposed. The third, center compartment was a transition zone between exposure and sham-exposure. In each experiment, the rats were individually assessed in 1-h sessions where half of the rats (n = 20) had the choice to locomote between the two sides being exposed or sham-exposed, while the other half of the rats (n = 20) were sham-exposed regardless of their location, except in one experiment where there was no sham-exposed group. The exposure levels for the first six experiments were 80, 55, 42.5, 30, -36, and -55 kV/m, respectively. The air ion concentration was constant at 1.4 x 10(6) ions/cc for the four positive exposure levels and -1.4 x 10(6) ions/cc for the two negative exposure levels. Rats having a choice between exposure and non-exposure relative to always sham-exposed control animals significantly reduced the amount of time spent on the exposed side at 80 kV/m (P < .002) as they did at both 55 and -55 kV/m (P < .005). No significant differences between groups were observed at 42.5, 30, or -36 kV/m. To determine what role the air ion concentration might have had on the avoidance behavior at field strengths of 55 kV/m or greater, four

  12. Effect of extremely low frequency electromagnetic field exposure on sleep quality in high voltage substations.

    PubMed

    Barsam, Tayebeh; Monazzam, Mohammad Reza; Haghdoost, Ali Akbar; Ghotbi, Mohammad Reza; Dehghan, Somayeh Farhang

    2012-11-30

    This study aims to investigate the effect of extremely low frequency electromagnetic fields exposure on sleep quality in high voltage substations (132, 230 and 400 KV) in Kerman city and the suburbs. For this purpose, the electric field intensity and magnetic flux density were measured in different parts of substations, and then the occupational exposure was estimated by averaging electric field intensity and magnetic flux density in a shift work. The cases comprised 67 workers who had been exposed to electromagnetic fields in age range of 24-57 and the controls were 110 persons the age ranged 24-50 years. Sleep quality of both groups was evaluated by the Pittsburgh Sleep Quality Index questionnaire (PSQI). Finally, these data were subjected to statistical analysis. The results indicated that 90.5% of cases and 85.3% of controls had the poor quality sleep according to PSQI (P-value=0.615). Total sleep quality score mean for the case and control groups were 10.22 ± 3.4 and 9.74 ± 3.62 (P-value=0.415) ,respectively. Meantime to fall asleep for cases(35.68 ± 26.25 min) was significantly higher than for controls (28.89 ± 20.18 min) (P-value=0.002). Cases had average sleep duration of 5.49 ± 1.31 hours, which was lower ascompared with control subjects (5.90 ± 1.67hours). Although there was a higher percentage for the case group with poor sleep quality than the control group, but no statistically significant difference was observed.

  13. Effect of extremely low frequency electromagnetic field exposure on sleep quality in high voltage substations

    PubMed Central

    2012-01-01

    This study aims to investigate the effect of extremely low frequency electromagnetic fields exposure on sleep quality in high voltage substations (132, 230 and 400 KV) in Kerman city and the suburbs. For this purpose, the electric field intensity and magnetic flux density were measured in different parts of substations, and then the occupational exposure was estimated by averaging electric field intensity and magnetic flux density in a shift work. The cases comprised 67 workers who had been exposed to electromagnetic fields in age range of 24–57 and the controls were 110 persons the age ranged 24–50 years. Sleep quality of both groups was evaluated by the Pittsburgh Sleep Quality Index questionnaire (PSQI). Finally, these data were subjected to statistical analysis. The results indicated that 90.5% of cases and 85.3% of controls had the poor quality sleep according to PSQI (P-value=0.615). Total sleep quality score mean for the case and control groups were 10.22 ± 3.4 and 9.74 ± 3.62 (P-value=0.415) ,respectively. Meantime to fall asleep for cases(35.68 ± 26.25 min) was significantly higher than for controls (28.89 ± 20.18 min) (P-value=0.002). Cases had average sleep duration of 5.49 ± 1.31 hours, which was lower ascompared with control subjects (5.90 ± 1.67hours). Although there was a higher percentage for the case group with poor sleep quality than the control group, but no statistically significant difference was observed. PMID:23369281

  14. Calibration of HIFU intensity fields measured using an infra-red camera

    NASA Astrophysics Data System (ADS)

    Shaw, A.; Khokhlova, V.; Bobkova, S.; Gavrilov, L.; Hand, J.

    2011-02-01

    A trend in HIFU technologies is to use 2D phased arrays that offer electronic steering of a single focus and formation of patterns of multiple foci. Conventional methods to characterize array fields using scanned hydrophone would be prohibitively slow given the potentially large number of focusing conditions. An alternative technique for rapid qualitative assessment of intensity distributions was recently developed. The method is based on infrared camera measurements of the temperature rises induced by low amplitude short ultrasonic bursts in a thin absorber. Here, the method is extended to estimate the absolute values of intensity in a field of a 2D 1-MHz randomized phased array. Two approaches were implemented. In the first approach it was assumed that the measured temperature rise at the surface of the absorber is proportional to the free field intensity. The second approach correlated the temperature rise measured in an absorber and calculated from the modelled acoustic field and the heat transfer equation. Corresponding correction factors between the free field intensity and temperature was obtained and introduced in the conversion of temperature images to intensity. Free field distributions in water and focusing through ribs were recorded and simulated. Good correlation between the measured and modeled results in both spatial distributions and the absolute values of intensity was demonstrated.

  15. Assessing human exposure to power-frequency electric and magnetic fields.

    PubMed Central

    Kaune, W T

    1993-01-01

    This paper reviews published literature and current problems relating to the assessment of occupational and residential human exposures to power-frequency electric and magnetic fields. Available occupational exposure data suggest that the class of job titles known as electrical workers may be an effective surrogate for time-weighted-average (TWA) magnetic-field (but not electric-field) exposure. Current research in occupational-exposure assessment is directed to the construction of job-exposure matrices based on electric- and magnetic-field measurements and estimates of worker exposures to chemicals and other factors of interest. Recent work has identified five principal sources of residential magnetic fields: electric power transmission lines, electric power distribution lines, ground currents, home wiring, and home appliances. Existing residential-exposure assessments have used one or more of the following techniques: questionnaires, wiring configuration coding, theoretical field calculations, spot electric- and magnetic-field measurements, fixed-site magnetic-field recordings, personal- exposure measurements, and geomagnetic-field measurements. Available normal-power magnetic-field data for residences differ substantially between studies. It is not known if these differences are due to geographical differences, differences in measurement protocols, or instrumentation differences. Wiring codes and measured magnetic fields (but not electric fields) are associated weakly. Available data suggest, but are far from proving, that spot measurements may be more effective than wire codes as predictors of long-term historical magnetic-field exposure. Two studies find that away-from-home TWA magnetic-field exposures are less variable than at-home exposures. The importance of home appliances as contributors to total residential magnetic-field exposure is not known at this time. It also is not known what characteristics (if any) of residential electric and magnetic fields are

  16. Biological effects of prolonged exposure to ELF electromagnetic fields in rats: III. 50 Hz electromagnetic fields.

    PubMed

    Zecca, L; Mantegazza, C; Margonato, V; Cerretelli, P; Caniatti, M; Piva, F; Dondi, D; Hagino, N

    1998-01-01

    Groups of adult male Sprague Dawley rats (64 rats each) were exposed for 8 months to electromagnetic fields (EMF) of two different field strength combinations: 5microT - 1kV/m and 100microT - 5kV/m. A third group was sham exposed. Field exposure was 8 hrs/day for 5 days/week. Blood samples were collected for hematology determinations before the onset of exposure and at 12 week intervals. At sacrifice, liver, heart, mesenteric lymph nodes, bone marrow, and testes were collected for morphology and histology assessments, while the pineal gland and brain were collected for biochemical determinations. At both field strength combinations, no pathological changes were observed in animal growth rate, in morphology and histology of the collected tissue specimens (liver, heart, mesenteric lymph nodes, testes, bone marrow), and in serum chemistry. An increase in norepinephrine levels occurred in the pineal gland of rats exposed to the higher field strength. The major changes in the brain involved the opioid system in frontal cortex, parietal cortex, and hippocampus. From the present findings it may be hypothesized that EMF may cause alteration of some brain functions.

  17. Influence of relative humidity on analyzing electric field exposure using ELF electric field measurements.

    PubMed

    Korpinen, Leena H; Kuisti, Harri A; Tarao, Hiroo; Elovaara, Jarmo A

    2013-07-01

    The objective of the study was to investigate the influence of humidity on analyzing electric field exposure using extremely low frequency (ELF) electric field measurements. The study included 322 measurements in a climate room. We used two commercial three-axis meters, EFA-3 and EFA-300, and employed two measurement techniques in the climate room where we varied the temperature from 15 to 25 °C, the relative humidity from 55% to 95%, and the electric field from 1 to 25 kV/m. We calculated Pearson correlations between humidity and percentage errors for all data and for data at different levels of humidity. When the relative humidity was below 70%, the results obtained by the different measurement methods in terms of percentage errors were of the same order of magnitude for the considered temperatures and field strength, but the results were less reliable when the relative humidity was higher than 80%. In the future, it is important to take humidity into account when electric field measurement results will be compared to the values given in different exposure guidelines. Copyright © 2013 Wiley Periodicals, Inc.

  18. Characterization of structural vibration: Field descriptors based on energy density and intensity

    NASA Astrophysics Data System (ADS)

    Linjama, Jukka

    Measurement of energy flow in acoustical and vibrational fields is usually based on the detection of one linear field quantity (e.g. sound pressure) and its spatial gradient, two transducers being used for the measurement. This report first reviews the quantities which can be obtained from the measurement of acoustical intensity with a two-microphone probe: intensity and the energy densities. A set of 'field descriptors', relative quantities giving a measure of propagating (active) character of the waves in the sound field, is proposed. These energetic quantities are based entirely on the transversal velocity measured and the gradient of that velocity, and are available when the two-transducer method of bending wave intensity is used. Examples of the energy densities and field descriptors measured in an aluminum plate are presented, and proposals for further work are given.

  19. Relationship between auroral electrojet intensity fluctuations and the wind field near the mesopause

    SciTech Connect

    Balsley, B.B.; Carter, D.A.; Ecklund, W.L.

    1982-03-01

    We report an observed correlation between short-term fluctuation in the wind field near the mesopause (happrox. =83--90 km) and intensity variations of the auroral electrojet (happrox. =110--115 km). Our results were obtained by comparing mesospheric wind variations obtained from the MST radar at Poker Flat, Alaska with electrojet intensity varitions determined by both the intensity of radar-auroral echoes and ground-based magnetometer data. The apparent correlation between these parameters suggests a partial control of the mesospheric wind field by the overlying current system.

  20. Correction of in situ cosmogenic nuclide production rates for geomagnetic field intensity variations during the past 800,000 years

    NASA Astrophysics Data System (ADS)

    Masarik, Jozef; Frank, Martin; Schäfer, Jörg M.; Wieler, Rainer

    2001-09-01

    We present integrated relative production rates for cosmogenic nuclides in rock surfaces, which take into account reported variations of the geomagnetic field intensity during the past 800,000 yr. The calculations are based on the model simulating cosmic ray particle interactions with the Earth's atmosphere given by Masarik and Beer ["Simulation of particle fluxes and cosmogenic nuclide production in the Earth's atmosphere," J. Geophys. Res. 104(D10), 12099-12111, 1999]. Corrections are nearly independent on altitude between sea level and at least 5000 m. The correction factors are essentially identical for all stable and radioactive cosmogenic nuclides with half-lives longer than a few hundred thousand years. At the equator, integrated production rates for exposure ages between ˜40,000 to 800,000 yr are 10 to 12% higher than the present-day values, whereas at latitudes >40°, geomagnetic field intensity variations have hardly influenced in situ cosmogenic nuclide production. Correction factors for in situ 14C production rates differ from those of longer-lived nuclides. They are always smaller than ˜2% because the magnetic field intensity remained rather constant during the past ˜10 kyr, when the major fraction of the 14C extant today was produced.

  1. Evaluation of nonuniform field exposures with coupling factors.

    PubMed

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

    2015-10-21

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

  2. Evaluation of nonuniform field exposures with coupling factors

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  3. Assessment of multiple frequency ELF electric and magnetic field exposure.

    PubMed

    Leitgeb, N

    2008-01-21

    Electromagnetic fields both in daily life and at workplaces exhibit increasingly complex frequency spectra. Present spectral assessment rules proved to be too conservative for health risk assessment. This is because they are based on the assumption that cells would react like linear systems in terms of responding to a sum of frequencies by a sum of independent responses to each individual frequency. Based on numerical investigations with the Hodgkin-Huxley and the Frankenhaeuser-Huxley nerve cell models, it could be shown that accounting for the nonlinear behaviour of cellular excitation processes avoids considerable overestimation of simultaneous exposures to multiple frequency ELF electric and magnetic fields. Besides this, it could be shown that the role of phase relationships is less important than that assumed so far. The present assessment rules lead to non-compliances of marketed electric appliances. For general application, a nonlinear biology-based assessment (NBBA) rule has been proposed, validated and proven advantageous compared with ICNIRP's rule. While staying conservative it avoids unnecessary overestimation and demonstrates compliance even in cases of suspected non-conformities. It is up to responsible bodies to decide upon the adoption of this proposal and the potential need for implementing additional or reducing the already incorporated safety factors.

  4. Assessment of multiple frequency ELF electric and magnetic field exposure

    NASA Astrophysics Data System (ADS)

    Leitgeb, N.

    2008-01-01

    Electromagnetic fields both in daily life and at workplaces exhibit increasingly complex frequency spectra. Present spectral assessment rules proved to be too conservative for health risk assessment. This is because they are based on the assumption that cells would react like linear systems in terms of responding to a sum of frequencies by a sum of independent responses to each individual frequency. Based on numerical investigations with the Hodgkin-Huxley and the Frankenhaeuser-Huxley nerve cell models, it could be shown that accounting for the nonlinear behaviour of cellular excitation processes avoids considerable overestimation of simultaneous exposures to multiple frequency ELF electric and magnetic fields. Besides this, it could be shown that the role of phase relationships is less important than that assumed so far. The present assessment rules lead to non-compliances of marketed electric appliances. For general application, a nonlinear biology-based assessment (NBBA) rule has been proposed, validated and proven advantageous compared with ICNIRP's rule. While staying conservative it avoids unnecessary overestimation and demonstrates compliance even in cases of suspected non-conformities. It is up to responsible bodies to decide upon the adoption of this proposal and the potential need for implementing additional or reducing the already incorporated safety factors.

  5. Occupational exposure in MR facilities due to movements in the static magnetic field.

    PubMed

    Andreuccetti, Daniele; Biagi, Laura; Burriesci, Giancarlo; Cannatà, Vittorio; Contessa, Gian Marco; Falsaperla, Rosaria; Genovese, Elisabetta; Lodato, Rossella; Lopresto, Vanni; Merla, Caterina; Napolitano, Antonio; Pinto, Rosanna; Tiberi, Gianluigi; Tosetti, Michela; Zoppetti, Nicola

    2017-08-30

    The exposure of operators moving in the static field of magnetic resonance (MR) facilities was assessed through measurements of the magnetic flux density, which is experienced as variable in time because of the movement. Collected data were processed to allow the comparison with most recent and authoritative safety standards. Measurements of the experienced magnetic flux density B were performed using a probe worn by volunteers moving in MR environments. A total of 55 datasets were acquired nearby a 1.5T, 3T and 7T whole body scanners. Three different metrics were applied: the maximum intensity of B, to be compared with 2013/35/EU Directive exposure limit values for static fields; the maximum variation of the vector B on every 3s-interval, for comparison with the ICNIRP-2014 basic restriction aimed at preventing vertigo effects; two weighted peak indices (for "sensory" and "health" effects: SENS-WP, HLTH-WP), assessing compliance with ICNIRP-2014 and EU Directive recommendations intended to prevent stimulation effects. Peak values of |B| were greater than 2T in 9 of the 55 datasets. All the datasets at 1.5T and 3T were compliant with the limit for vertigo effects, whereas 6 datasets at 7T turned out to be non-compliant. At 7T, all 36 datasets were non-compliant for the SENS-WP index and 26 datasets even for the HLTH-WP one. Results demonstrate that compliance with EU Directive limits for static fields does not guarantee compliance with ICNIRP-2014 reference levels and clearly show that movements in the static field could be the key component of the occupational exposure to EMF in MR facilities. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  6. Net effect of many gravitational fields on the intensity of celestial light sources. Master's thesis

    SciTech Connect

    Cipperly, G.E.

    1982-12-01

    This thesis investigates the lens-like action of the gravitational fields of celestial bodies, which can alter the apparent intensity of more distant sources. Previous work in this area has shown that the chance of an individual body being sufficiently well aligned with a source to cause a very large gravitational intensity change is small. The issue addressed in this study is the possibility of there being a significant total change in the intensity of a source due to the combined effects of the gravitational fields of all celestial bodies, and in particular, the potential impact on intensity distance measurements, that is, determination of the distances of celestial light sources by means of intensity comparisons. It is first shown that the problem can be treated in flat space by associating an appropriate index of refraction with gravitational fields. A wave approach is taken in deriving the total deflection of a ray by the field of a single point mass. A statistical analysis is then performed to determine the expression for the mean total change in the intensity of celestial light sources due to the combined fields of all intervening bodies.

  7. 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...

  8. 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...

  9. Influence of exposure to electromagnetic field on the cardiovascular system.

    PubMed

    Jeong, J H; Kim, J S; Lee, B C; Min, Y S; Kim, D S; Ryu, J S; Soh, K S; Seo, K M; Sohn, U D

    2005-01-01

    1 We examined whether extremely low frequency electromagnetic fields (ELF-EMF) affect the basal level of cardiovascular parameters and influence of drugs acting on the sympathetic nervous system. 2 Male rats were exposed to sham control and EMF (60 Hz, 20 G) for 1 (MF-1) or 5 days (MF-5). We evaluated the alterations of blood pressure (BP), pulse pressure (PP), heart rate (HR), and the PR interval, QRS interval and QT interval on the electrocardiogram and dysrhythmic ratio in basal level and dysrhythmia induced by beta-adrenoceptor agonists. 3 In terms of the basal levels, there were no statistically significant differences among control, MF-1 and MF-5 in PR interval, QRS interval, mean BP, HR and PP. However, the QT interval, representing ventricular repolarization, was significantly reduced by MF-1 (P < 0.05). 4 (-)-Dobutamine (beta1-adrenoceptor-selective agonist)-induced tachycardia was significantly suppressed by ELF-EMF exposure in MF-1 for the increase in HR (DeltaHR), the decrease in QRS interval (DeltaQRS) and the decrease in QT (DeltaQT) interval. Adrenaline (nonselective beta-receptor agonist)-induced dysrhythmia was also significantly suppressed by ELF-EMF in MF-1 for the number of missing beats, the dysrhythmic ratio, and the increase in BP and PP. 5 These results indicated that 1-day exposure to ELF-EMF (60 Hz, 20 G) could suppress the increase in HR by affecting ventricular repolarization and may have a down-regulatory effect on responses of the cardiovascular system induced by sympathetic agonists.

  10. Strengthening Collaborative Capacity: Experiences from a Short, Intensive Field Course on Ecosystems, Health and Society

    ERIC Educational Resources Information Center

    Parkes, Margot W.; Saint-Charles, Johanne; Cole, Donald C.; Gislason, Maya; Hicks, Elisabeth; Le Bourdais, Courtney; McKellar, Kaileah A.; St-Cyr Bouchard, Maude

    2017-01-01

    A key capacity for engagement in the emerging field of ecohealth is the ability to work collaboratively. Between 2008 and 2010, the Canadian Community of Practice in Ecosystem Approaches to Health collectively designed and delivered three foundational, intensive, field courses. This paper presents findings derived from both quantitative and…

  11. SHEDS-HT: an integrated probabilistic exposure model for prioritizing exposures to chemicals with near-field and dietary sources.

    PubMed

    Isaacs, Kristin K; Glen, W Graham; Egeghy, Peter; Goldsmith, Michael-Rock; Smith, Luther; Vallero, Daniel; Brooks, Raina; Grulke, Christopher M; Özkaynak, Halûk

    2014-11-04

    United States Environmental Protection Agency (USEPA) researchers are developing a strategy for high-throughput (HT) exposure-based prioritization of chemicals under the ExpoCast program. These novel modeling approaches for evaluating chemicals based on their potential for biologically relevant human exposures will inform toxicity testing and prioritization for chemical risk assessment. Based on probabilistic methods and algorithms developed for The Stochastic Human Exposure and Dose Simulation Model for Multimedia, Multipathway Chemicals (SHEDS-MM), a new mechanistic modeling approach has been developed to accommodate high-throughput (HT) assessment of exposure potential. In this SHEDS-HT model, the residential and dietary modules of SHEDS-MM have been operationally modified to reduce the user burden, input data demands, and run times of the higher-tier model, while maintaining critical features and inputs that influence exposure. The model has been implemented in R; the modeling framework links chemicals to consumer product categories or food groups (and thus exposure scenarios) to predict HT exposures and intake doses. Initially, SHEDS-HT has been applied to 2507 organic chemicals associated with consumer products and agricultural pesticides. These evaluations employ data from recent USEPA efforts to characterize usage (prevalence, frequency, and magnitude), chemical composition, and exposure scenarios for a wide range of consumer products. In modeling indirect exposures from near-field sources, SHEDS-HT employs a fugacity-based module to estimate concentrations in indoor environmental media. The concentration estimates, along with relevant exposure factors and human activity data, are then used by the model to rapidly generate probabilistic population distributions of near-field indirect exposures via dermal, nondietary ingestion, and inhalation pathways. Pathway-specific estimates of near-field direct exposures from consumer products are also modeled

  12. Light fields with an axially expanded intensity distribution for stable three-dimensional optical trapping.

    PubMed

    Zwick, Susanne; Schaub, Christian; Haist, Tobias; Osten, Wolfgang

    2010-09-13

    We introduce a new kind of light field to improve and simplify the trapping process of axially displaced particles. To this end we employ a light field with an axially expanded intensity distribution, which at the same time enables stable axial trapping. We present simulations of the axial intensity distribution of the novel trapping field and first experimental results, which demonstrate the improvement of the reliability of the axial trapping process. The method can be used to automate trapping of particles that are located outside of the focal plane of the microscope.

  13. Intense terahertz field effects on photoexcited carrier dynamics in gated graphene

    NASA Astrophysics Data System (ADS)

    Hafez, Hassan A.; Lévesque, Pierre L.; Al-Naib, Ibraheem; Dignam, Marc M.; Chai, Xin; Choubak, Saman; Desjardins, Patrick; Martel, Richard; Ozaki, Tsuneyuki

    2015-12-01

    We study nonlinear effects of intense terahertz (THz) field on photoexcited carrier dynamics in gated monolayer graphene. By employing optical-pump/intense-THz-probe spectroscopy on lightly doped graphene, we observe a crossover from negative to positive photo-induced THz differential transmission as the THz probe field is increased. We attribute this qualitative change in the response to a crossover from a regime where the photo-induced increase in the carrier density dominates the differential response to one where a THz-field-induced increase in the scattering rate dominates.

  14. [Association of age and sex with intensity of exposure to bicycle use in Spain, 1993-2009].

    PubMed

    Martínez Ruiz, V; Jiménez Mejías, E; Amezcua Prieto, C; Luna del Castillo, J D; Jiménez Moleón, J J; Lardelli Claret, P

    2014-01-01

    To estimate the association of age and sex with the intensity of exposure of cyclists in Spain, between 1993 and 2009, in a global way and for subtypes of use. From the distribution of cyclists passively involved in collisions with other vehicles included in the register of the Spanish General Traffic Directorate between 1993 and 2009, we have estimated the increase in intensity of exposure by age groups and sex, for global exposure and for subtypes of exposure (e.g. riding with or without a helmet, or riding on an open road or in urban areas), using males aged 45-49 as a reference. Males have a greater exposure than females and this difference increases with age, although it has tended to decrease in recent years. In both sexes the exposure is greater in young people and goes down with age, while in males the excess in young people has disappeared in recent years. Regarding subtypes of use, female underexposure riding on an open road should be highlighted, as well as overexposure in both women and extreme age groups among non-helmet users. There is a close association of age and sex with the intensity of bicycle use, which changes depending on the type of use and the time period considered. Consequently, estimations of the effect of factors affecting the accident rate and the morbidity and mortality of cyclists in Spain have to be adjusted by the age and sex of the cyclist.

  15. Phase-shift nano-emulsions induced cavitation and ablation during high intensity focused ultrasound exposure

    NASA Astrophysics Data System (ADS)

    Qiao, Yangzi; Yin, Hui; Chang, Nan; Wan, Mingxi

    2017-03-01

    Phase-shift Nano-emulsions (PSNEs) with a small initial diameter in nanoscale have the potential to leak out of the blood vessels and to accumulate at target point of tissue. At desired location, PSNEs can undergo acoustic droplet vaporization (ADV) process, change into gas bubbles and enhance focused ultrasound efficiency. The aim of this work was to provide spatial and temporal information on PSNE induced cavitation and ablation effects during pulsed high intensity focused ultrasound (HIFU) exposure. The PSNEs were composed of perfluorohaxane (PFH) and bovine serum albumin (BSA), and then uniformly distributed in a transparent polyacrylamide phantom. The Sonoluminescence (SL) method was employed to visualize the cavitation distribution and formation process of PSNEs induced cavitation. For the phantom which was used for ablation observation, heat sensitive BSA was added. When the temperature generated by ultrasound exposure was high enough to denature BSA, the transparent phantom would turn out white lesions. The shape of the lesion and the formation process were compared with those of cavitation. Each of the pulse contained 12 cycles for a duration of 10 µs. And the duty cycle changed from 1:10 to 1:40. The total "on" time of HIFU was 2s. PSNE can evidently accelerate cavitation emitting bright SL in pre-focal region. The cavitation was generated layer by layer towards the transducer. The formed bubble wall can block acoustic waves transmitting to the distal end. And the lesion appeared to be separated into two parts. One in pre-focal region stemmed from one point and grew quickly toward the transducer. The other in focal region was formed by merging some small white dots, and grew much slower. The influence of duty cycle has also been examined. The lower duty cycle with longer pulse-off time would generate more intense cavitation, however, smaller lesion. Bubble cloud gradually developed within phantom would greatly influence the cavitation and ablation

  16. Radiation Exposure to Premature Infants in a Neonatal Intensive Care Unit in Turkey

    PubMed Central

    Onal, Esra; Bor, Dogan; Okumus, Nurullah; Atalay, Yildiz; Turkyilmaz, Canan; Ergenekon, Ebru; Koc, Esin

    2008-01-01

    Objective The aim of this work was to determine the radiation dose received by infants from radiographic exposure and the contribution from scatter radiation due to radiographic exposure of other infants in the same room. Materials and Methods We retrospectively evaluated the entrance skin doses (ESDs) and effective doses of 23 infants with a gestational age as low as 28 weeks. ESDs were determined from tube output measurements (ESDTO) (n = 23) and from the use of thermoluminescent dosimetry (ESDTLD) (n = 16). Scattered radiation was evaluated using a 5 cm Perspex phantom. Effective doses were estimated from ESDTO by Monte Carlo computed software and radiation risks were estimated from the effective dose. ESDTO and ESDTLD were correlated using linear regression analysis. Results The mean ESDTO for the chest and abdomen were 67 µGy and 65 µGy per procedure, respectively. The mean ESDTLD per radiograph was 70 µGy. The measured scattered radiation range at a 2 m distance from the neonatal intensive care unit (NICU) was (11-17 µGy) per radiograph. Mean effective doses were 16 and 27 µSv per procedure for the chest and abdomen, respectively. ESDTLD was well correlated with ESDTO obtained from the total chest and abdomen radiographs for each infant (R2 = 0.86). The radiation risks for childhood cancer estimated from the effective dose were 0.4 × 10-6 to 2 × 10-6 and 0.6 × 10-6 to 2.9 × 10-6 for chest and abdomen radiographs, respectively. Conclusion The results of our study show that neonates received acceptable doses from common radiological examinations. Although the contribution of scatter radiation to the neonatal dose is low, considering the sensitivity of the neonates to radiation, further protective action was performed by increasing the distance of the infants from each other. PMID:18838850

  17. Histological evaluation of high-intensity focused ultrasound with lower-intensity focused ultrasound pre-exposure on the treatment of rabbit VX2 liver tumors

    SciTech Connect

    Zou Hairong; Zou Jianzhong; Wang Yan; Ou Xia

    2012-10-03

    This study was to evaluate the effect of pre-exposure lower-intensity focused ultrasound(US), or LIFU, in high-intensity focused ultrasound(HIFU) ablation of rabbit VX2 liver tumors . Liver VX2 tumor models were established in 30 rabbits, which were divided randomly into two groups. The liver tumors of rabbits in Group A underwent single HIFU ablation; those in Group B were given LIFU exposure before HIFU treatment. Five rabbits from each of the two groups were sacrificed at 0 hours, 3 days, and 7 days after HIFU ablation. Tissue samples that included targeted and short-range sounding (s-RS, within 5 mm of the targeted) and far-range sounding (f-RS, more than 5 mm of the targeted) tissues were observed using light microscope and transmission electron microscopy. The histological examination indicated that not only the targeted tumor cells became irreversible damage, but also the short-range sounding tumors were severely damaged by the HIFU with LIFU pre-exposure in group B. It is concluded that LIFU pre-exposure can enhance the effects of HIFU ablation on the destruction of cell ultrastructures and can enlarge the region of HIFU ablation.

  18. Effects of exposure to extremely low frequency magnetic fields on spermatogenesis in adult rats.

    PubMed

    Duan, Weixia; Liu, Chuan; Wu, Hongjuan; Chen, Chunhai; Zhang, Tao; Gao, Peng; Luo, Xue; Yu, Zhengping; Zhou, Zhou

    2014-01-01

    The constant exposure of modern society to extremely low frequency magnetic fields (ELF-MF) has raised considerable concerns about the potential risks to male reproduction. However, the epidemiological and experimental data remain contradictory and inconclusive. In the present study, we investigated the effects of 50 Hz ELF-MF of 500 µT applied 4 h/day, 7 days/week for 4 and 8 weeks on male reproduction, focusing on changes in spermatogenesis. Several biological endpoints related to testicular function and spermatogenesis were measured, including the following: body mass, masses of testes and epididymis, sperm count and abnormal sperm ratio in the caudal epididymis, serum testosterone level, testicular histology, frequency of 14 stages of the cycle of the seminiferous epithelium and of four stages of meiosis I, germ cell apoptosis and testicular oxidative status. No significant differences were found in the biological endpoints between the sham control and the exposed rats in either the 4- or 8-week exposure period. These negative results may result from the lack of change in serum testosterone. In conclusion, our study indicates that exposure to low intensity ELF-MF may have no adverse effects on spermatogenesis.

  19. Development and Application of Integrated Optical Sensors for Intense E-Field Measurement

    PubMed Central

    Zeng, Rong; Wang, Bo; Niu, Ben; Yu, Zhanqing

    2012-01-01

    The measurement of intense E-fields is a fundamental need in various research areas. Integrated optical E-field sensors (IOESs) have important advantages and are potentially suitable for intense E-field detection. This paper comprehensively reviews the development and applications of several types of IOESs over the last 30 years, including the Mach-Zehnder interferometer (MZI), coupler interferometer (CI) and common path interferometer (CPI). The features of the different types of IOESs are compared, showing that the MZI has higher sensitivity, the CI has a controllable optical bias, and the CPI has better temperature stability. More specifically, the improvement work of applying IOESs to intense E-field measurement is illustrated. Finally, typical uses of IOESs in the measurement of intense E-fields are demonstrated, including application areas such as E-fields with different frequency ranges in high-voltage engineering, simulated nuclear electromagnetic pulse in high-power electromagnetic pulses, and ion-accelerating field in high-energy physics. PMID:23112663

  20. Modeling microbial survival during exposure to a lethal agent with varying intensity.

    PubMed

    Peleg, M; Penchina, C M

    2000-03-01

    Traditionally, the efficacy of preservation and disinfection processes has been assessed on the basis of the assumption that microbial mortality follows a first-order kinetic. However, as departures from this assumed kinetics are quite common, various other models, based on higher-order kinetics or population balance, have also been proposed. The database for either type of models is a set of survival curves of the targeted organism or spores determined under constant conditions, that is, constant temperature, chemical agent concentration, etc. Hence, to calculate the outcome of an actual industrial process, where conditions are changing, as in heating and cooling during a thermal treatment or when the agent dissipates as in chlorination or hydrogen peroxide application, one has to integrate the momentary effects of the lethal agent. This involves mathematical models based on assumed mortality kinetics, and simulated or measured history, for example, temperature-time or concentration-time relationships at the "coldest" point. It is shown that the survival curve under conditions where the agent intensity increases, decreases, or oscillates can be constructed without assuming any mortality kinetics and without the use of the traditional D and Z values, which require linear approximation, and without thermal death times, which require extrapolation. The actual survival curves can be compiled from the isothermal survival curves provided that growth and damage repair do not occur over the pertinent time scale and that the mortality rate is a function of only the momentary agent intensity and of the organism's or spore's survival fraction (but not of the rate at which this fraction has been reached). The calculation is greatly facilitated if both the "isothermal" survival curves and the time-dependent agent intensity can be expressed algebraically. The differential equation derived from these considerations can be solved numerically to produce the required survival curve

  1. Early embryonic development of frogs under intense magnetic fields up to 8 T

    NASA Astrophysics Data System (ADS)

    Ueno, S.; Iwasaka, M.; Shiokawa, K.

    1994-05-01

    A possible influence of intense magnetic fields on the embryonic development of frogs was studied in reference to a potential hazard in magnetic resonance imaging technology. Some of the most serious hazardous effects that could be induced by intense magnetic fields are teratogenic effects on developing embryos. In the present experiment, the possible influence of intense magnetic fields up to 8 T on the early embryonic development of Xenopus laevis was studied. Embryos were exposed to magnetic fields up to 8 T for the period from the precleavage stage to neurula in a small glass vial. Embryos were then cultured in Brown-Caston's medium until the feeding-tadpole stage. No apparent teratogenic effects were observed when embryos were cultured for 20 h from the stage of uncleaved fertilized egg to the neurula stage under magnetic fields of 8 T. We conclude that static magnetic fields up to 8 T do not appreciably affect the rapid cleavage and the following cell multiplication and differentiation in Xenopus laevis. We have also studied the early embryonic development of Xenopus laevis in a 40 nT magnetic field, or 1/1000 of the earth's magnetic field, and obtained negative results. Thus, again under this very low magnetic field, fertilized eggs developed normally and formed tadpoles with no appreciable abnormality.

  2. Cholinergic transmission underlies modulation of frustration by open field exposure.

    PubMed

    Psyrdellis, Mariana; Pautassi, Ricardo Marcos; Mustaca, Alba; Justel, Nadia

    2016-01-01

    Frustration can be defined as an emotional state generated by the omission or devaluation in the quantity or quality of an expected appetitive reward. Thus, reactivity to a reward is affected by prior experience with the different reinforcer values of that reward. This phenomenon is known as incentive relativity, and can be studied by different paradigms. Although methodologically simple, the exploration of a novel open field (OF) is a complex situation that involves several behavioral processes, including stress induction and novelty detection. OF exposure can enhance or block the acquisition of associative and non-associative memories. These experiments evaluated the effect of OF exploration on frustration and the role played by the cholinergic system in this phenomenon. OF exploration before first or second trial of incentive downshift modulated the expression of frustration. This effect of OF was blocked by the administration of scopolamine either before or after OF exploration. These results indicate that the cholinergic system is involved in the acquisition and consolidation of OF information.

  3. Variability and consistency of electric and magnetic field occupational exposure measurements.

    PubMed

    Bracken, T D; Patterson, R M

    1996-01-01

    There is widespread scientific and public interest in possible health effects from exposure to electric and magnetic fields at frequencies associated with electricity use. Electric and magnetic field exposure assessment presents specific problems, among which are the inherent variability in exposure, the lack of robust statistical summary measures, and the lack of an accepted metric based on biological response. These pose challenges in defining distinct exposure groups, a basic goal for exposure assessments used in epidemiological studies. This paper explores the extent to which distinct electric and magnetic field exposure groups can be defined, by examining the variability and consistency of occupational electric and magnetic field exposure measurements among studies and within individual studies. Principal analyses are made by job titles because they are the most frequently used descriptors for stratifying occupational exposures to electric and magnetic fields. Methodological issues affecting the degree of consistency in measured electric and magnetic field exposures among occupational environments are also examined. Exposures by job title reported from electric and magnetic field measurement studies are summarized by general job category and industry. Analyses are performed both within and between job categories. Distributions of daily measured exposures for job categories taken from three large studies in the U.S. electric utility industry are compared to investigate consistency of exposures at a more detailed level. Analyses of reported personal exposure measurements from many studies and countries are consistent with less rigorous observations made heretofore on the basis of individual studies. In these studies, significantly elevated electric and magnetic field exposures are found in the electrician, lineworker, and substation worker categories; significantly elevated magnetic field exposures are also noted in the generation worker category; and magnetic

  4. Chronic exposure to pulsed low-intensity microwaves is carcinogenic and tumorogenic

    NASA Astrophysics Data System (ADS)

    Lundquist, Marjorie

    2004-03-01

    To study health effects of lifetime exposure to low-intensity pulsed radiation >890 MHz, one controlled laboratory study of SPF* rats[1-3] and two of mice[4,5] were conducted, but only one[4] reported that its data showed an association between irradiation and cancer; reports of the other two studies minimized or denied such association. Critical review of these identified data evaluation errors; their correction enables a conclusion of microwave carcinogenicity from each study (the rat study also shows an association with endocrine-system primary malignancies and with a benign tumor of the adrenal medulla), enhancing the credibility of an epidemiological study[6] reporting a brain cancer risk for users of both analog and digital cellular phones. [1] J. Raloff. Science News 126(7):103(1984). [2] K. R. Foster & A. W. Guy. Sci Am 255(3):32-39(1986). [3] C.-K. Chou et al. Bioelectromagnetics 13:469-496(1992). [4] M. H. Repacholi et al. Radiat Res 147:631-640(1990)SPF\\. [5] T. D. Utteridge et al. Radiat Res 158:357-364(2002)non-SPF\\. [6] L. Hardell et al. Int J Oncol 22:399-407(2003). * SPF = specific-pathogen-free

  5. Hemodynamic retrieval intensity in hippocampus is decreased by pre-exposure to autobiographic test items.

    PubMed

    Rekkas, P Vivien; Constable, R Todd

    2006-10-16

    The purpose of this experiment was to assess the effects of probe familiarity, the consequences of having recently retrieved an autobiographic memory (AM), on subsequent recall. This was accomplished by replicating an earlier imaging experiment, using the same participants and memory probes. Subtractions between sessions showed significant pre-exposure effects (i.e., drop in BOLD signal intensity) in the prefrontal cortex, thalamus, cerebellum and other brain structures. Further, region of interest (ROI) analysis illustrated a significant decrease in neural activity in the hippocampus in both conditions. The results are discussed in terms of the pre-scan interview technique, a method applied in AM research to procure personal information. Although invaluable, we emphasize it must be used with caution as it can result in a loss of power. The widespread use of this method in AM research may explain why studies often fail to find evidence of significant responding in the hippocampus in response to memory probes. Alternatively, when activity in the hippocampus is reported, it often fails to differentiate between recent and remote memories. This point is of particular importance to the on-going consolidation debate, as it often centers on a failure to detect an effect in the hippocampus in one or both conditions.

  6. Effects of different intensities of extremely low frequency pulsed electromagnetic fields on formation of osteoclast-like cells.

    PubMed

    Chang, Kyle; Chang, Walter Hong-Shong; Wu, Mei-Ling; Shih, Chung

    2003-09-01

    Over the past 30 years, the beneficial therapeutic effects of selected low energy, time varying electromagnetic fields (EMF) have been documented with increasing frequency to treat therapeutically resistant problems of the musculoskeletal system. However, the underlying mechanisms at a cellular level are still not completely understood. In this study, the effects of extremely low frequency pulsed electromagnetic fields (ELF-PEMF) on osteoclastogenesis, cultured from murine bone marrow cells and stimulated by 1,25(OH)(2)D(3), were examined. Primary bone marrow cells were cultured from mature Wistar rats and exposed to ELF-PEMF stimulation daily for 7 days with different intensities of induced electric field (4.8, 8.7, and 12.2 micro V/cm rms) and stimulation times (0.5, 2, and 8 h/day). Recruitment and authentication of osteoclast-like cells were evaluated, respectively, by determining multinuclear, tartrate resistant acid phosphatase (TRAP) positive cells on day 8 of culture and by the pit formation assay. During the experiments, cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin 1-beta (IL-1beta), and prostaglandin-E(2) (PGE(2)) were assayed using the enzyme linked immunosorbent assay (ELISA). These findings suggest that ELF-PEMF can both enhance (approximately 50%) and suppress (approximately 27%) the formation of osteoclast-like cells in bone marrow culture, depending on the induced electric field intensity. In addition, consistent correlations were observed between TNF-alpha, IL-1beta, and osteoclast-like cell number after exposure to different induced electric field intensities of ELF-PEMF. This in vitro study could be considered as groundwork for in vivo ELF-PEMF clinical applications on some osteoclast-associated bone diseases.

  7. Effects of Mass Media Campaign Exposure Intensity and Durability on Quit Attempts in a Population-Based Cohort Study

    ERIC Educational Resources Information Center

    Wakefield, M. A.; Spittal, M. J.; Yong, H-H.; Durkin, S. J.; Borland, R.

    2011-01-01

    Objective: To assess the extent to which intensity and timing of televised anti-smoking advertising emphasizing the serious harms of smoking influences quit attempts. Methods: Using advertising gross rating points (GRPs), we estimated exposure to tobacco control and nicotine replacement therapy (NRT) advertising in the 3, 4-6, 7-9 and 10-12 months…

  8. Effects of Mass Media Campaign Exposure Intensity and Durability on Quit Attempts in a Population-Based Cohort Study

    ERIC Educational Resources Information Center

    Wakefield, M. A.; Spittal, M. J.; Yong, H-H.; Durkin, S. J.; Borland, R.

    2011-01-01

    Objective: To assess the extent to which intensity and timing of televised anti-smoking advertising emphasizing the serious harms of smoking influences quit attempts. Methods: Using advertising gross rating points (GRPs), we estimated exposure to tobacco control and nicotine replacement therapy (NRT) advertising in the 3, 4-6, 7-9 and 10-12 months…

  9. [Risk of neoplastic diseases in conditions of exposure to radio- and microwave fields--epidemiologic investigations].

    PubMed

    Szmigielski, Stanisław; Sobiczewska, Elzbieta

    2009-01-01

    The review presents current state of knowledge of cancer morbidity in persons exposed to radio- or microwave radiation in the environment or at working posts. The problem of cancer morbidity in persons exposed to microwaves was for many years limited to occupational medicine, but the introduction of mobile telephone system in the 1980s considerably increased the number of persons exposed to this radiation and raised concerns about cancer risks in the users of mobile phones. Cancer risks of microwaves are minor and doubtful, but there exist reliable epidemiologic investigations providing evidence that multiyear occupational exposure and intensive use of mobile phones for more than 10 years may cause the increased morbidity of certain types of neoplasms, mainly brain tumors, as well as hematopoietic and lymphatic malignancies. Neverthelesscurrent state of knowledge does not allow, according to the IARC classification, to classify radio- and microwave fields as the carcinogenic factor.

  10. Generation of intense magnetic field in a counter-streaming system

    NASA Astrophysics Data System (ADS)

    Yin, Yan

    2016-10-01

    Intense magnetic field generation by excitation of Weibel instability in dense plasmas has been investigated using particle-in-cell (PIC) simulations. As energetic electrons driven by laser propagate in dense plasmas, a return current is excited to compensate the charge neutrality offset. In such a counter-streaming system, Weibel instability is driven, leading to current filamentation and magnetic field generation. The current filaments self-organize in coaxial structures where the relativistic current in the center is surrounded by the return current sheath and intense magnetic field. The magnetic field peaks in the current center with magnitude as high as several hundreds of MegaGauss, and decreases to zero outside the relativistic current. The influences of counter-streaming density and energy on the magnetic field generation are examined.

  11. Surface area generation and droplet size control in solvent extraction systems utilizing high intensity electric fields

    DOEpatents

    Scott, Timothy C.; Wham, Robert M.

    1988-01-01

    A method and system for solvent extraction where droplets are shattered by a high intensity electric field. These shattered droplets form a plurality of smaller droplets which have a greater combined surface area than the original droplet. Dispersion, coalescence and phase separation are accomplished in one vessel through the use of the single pulsing high intensity electric field. Electric field conditions are chosen so that simultaneous dispersion and coalescence are taking place in the emulsion formed in the electric field. The electric field creates a large amount of interfacial surface area for solvent extraction when the droplet is disintegrated and is capable of controlling droplet size and thus droplet stability. These operations take place in the presence of a counter current flow of the continuous phase.

  12. Control of Goos-Hänchen shift via input probe field intensity

    NASA Astrophysics Data System (ADS)

    Ziauddin; Lee, Ray-Kuang; Qamar, Sajid

    2016-11-01

    We suggest a scheme to control Goos-Hänchen (GH) shift in an ensemble of strongly interacting Rydberg atoms, which act as super-atoms due to the dipole blockade mechanism. The ensemble of three-level cold Rydberg-dressed (87Rb) atoms follows a cascade configurations where two fields, i.e, a strong control and a weak field are employed [D. Petrosyan, J. Otterbach, and M. Fleischhauer, Phys. Rev. Lett. 107, 213601 (2011)]. The propagation of probe field is influenced by two-photon correlation within the blockade distance, which are damped due to the saturation of super-atoms. The amplitude of GH shift in the reflected light depends on the intensity of probe field. We observe large negative GH shift in the reflected light for small values of the probe field intensities.

  13. Intense-field-stimulated multiphoton transitions in a two-level system

    SciTech Connect

    Milman, Perola; Zagury, Nicim

    2011-11-15

    We study the interaction of an intense classical field with a two-level system coupled to a bosonic quantized field. We focus on the regime where the classical field and the two-level system characteristic frequencies are the same, while the quantized mode is set off resonance with both. We show that a parameter governing the dynamics of the system is the ratio between the classical field's intensity and the quantized mode detuning. Depending on this parameter, multiple excitations can be created in the quantized mode in a single cycle of the two-level system. Examples of physical setups allowing for the application of the presented ideas are superconducting circuits in strip-line resonators, laser cooled trapped ions, and neutral atoms coupled to the quantized field of a cavity. We focus on the latter in order to show that, with realistic experimental parameters, it is possible to generate up to four photons in a single Rabi cycle.

  14. Eight thousand years of geomagnetic field intensity variations in the eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Genevey, AgnèS.; Gallet, Yves; Margueron, Jean-Claude

    2003-05-01

    Twenty new intensity determinations of the ancient geomagnetic field have been obtained from groups of potsherds and brick fragments from Syria. These artifacts, archeologically well dated from ˜6000 B.C. to approximately A.D. 1200, have been analyzed using the [1959] method as modified by [1967]. Intensity values have been corrected for the effects of anisotropy of thermal remanent magnetization and cooling rate. Our results indicate that field intensities were moderate in Syria from ˜6000 B.C. to ˜3500 B.C., with values of ˜30-40 μT. There was a significant increase in intensity by a factor of 2 from ˜3500 B.C. to ˜700 B.C., which was interrupted by a moderate decrease between ˜2550 B.C. and ˜1750 B.C. During more recent periods, our results show an intensity minimum approximately A.D. 200 and a maximum around the tenth century. Comparison with different data sets from the eastern Mediterranean and central Asia shows that geomagnetic field intensity variations were consistent at this large regional scale, at least over the last 5 millennia.

  15. Infrared mapping of ultrasound fields generated by medical transducers: feasibility of determining absolute intensity levels.

    PubMed

    Khokhlova, Vera A; Shmeleva, Svetlana M; Gavrilov, Leonid R; Martin, Eleanor; Sadhoo, Neelaksh; Shaw, Adam

    2013-08-01

    Considerable progress has been achieved in the use of infrared (IR) techniques for qualitative mapping of acoustic fields of high intensity focused ultrasound (HIFU) transducers. The authors have previously developed and demonstrated a method based on IR camera measurement of the temperature rise induced in an absorber less than 2 mm thick by ultrasonic bursts of less than 1 s duration. The goal of this paper was to make the method more quantitative and estimate the absolute intensity distributions by determining an overall calibration factor for the absorber and camera system. The implemented approach involved correlating the temperature rise measured in an absorber using an IR camera with the pressure distribution measured in water using a hydrophone. The measurements were conducted for two HIFU transducers and a flat physiotherapy transducer of 1 MHz frequency. Corresponding correction factors between the free field intensity and temperature were obtained and allowed the conversion of temperature images to intensity distributions. The system described here was able to map in good detail focused and unfocused ultrasound fields with sub-millimeter structure and with local time average intensity from below 0.1 W/cm(2) to at least 50 W/cm(2). Significantly higher intensities could be measured simply by reducing the duty cycle.

  16. Infrared mapping of ultrasound fields generated by medical transducers: Feasibility of determining absolute intensity levels

    PubMed Central

    Khokhlova, Vera A.; Shmeleva, Svetlana M.; Gavrilov, Leonid R.; Martin, Eleanor; Sadhoo, Neelaksh; Shaw, Adam

    2013-01-01

    Considerable progress has been achieved in the use of infrared (IR) techniques for qualitative mapping of acoustic fields of high intensity focused ultrasound (HIFU) transducers. The authors have previously developed and demonstrated a method based on IR camera measurement of the temperature rise induced in an absorber less than 2 mm thick by ultrasonic bursts of less than 1 s duration. The goal of this paper was to make the method more quantitative and estimate the absolute intensity distributions by determining an overall calibration factor for the absorber and camera system. The implemented approach involved correlating the temperature rise measured in an absorber using an IR camera with the pressure distribution measured in water using a hydrophone. The measurements were conducted for two HIFU transducers and a flat physiotherapy transducer of 1 MHz frequency. Corresponding correction factors between the free field intensity and temperature were obtained and allowed the conversion of temperature images to intensity distributions. The system described here was able to map in good detail focused and unfocused ultrasound fields with sub-millimeter structure and with local time average intensity from below 0.1 W/cm2 to at least 50 W/cm2. Significantly higher intensities could be measured simply by reducing the duty cycle. PMID:23927199

  17. Electron Raman scattering in a double quantum well tuned by an external nonresonant intense laser field

    NASA Astrophysics Data System (ADS)

    Tiutiunnyk, A.; Mora-Ramos, M. E.; Morales, A. L.; Duque, C. M.; Restrepo, R. L.; Ungan, F.; Martínez-Orozco, J. C.; Kasapoglu, E.; Duque, C. A.

    2017-02-01

    In this work we shall present a study of inelastic light scattering involving inter-subband electron transitions in coupled GaAs-(Ga,Al)As quantum wells. Calculations include the electron related Raman differential cross section and Raman gain. The effects of an external nonresonant intense laser field are used in order to tune these output properties. The confined electron states will be described by means of a diagonalization procedure within the effective mass and parabolic band approximations. It is shown that the application of the intense laser field can produce values of the intersubband electron Raman gain above 400 cm-1. The system proposed here is an alternative choice for the development of AlxGa1-xAs semiconductor laser diodes that can be tuned via an external nonresonant intense laser field.

  18. Dynamical coupling of electrons and nuclei for Coulomb explosion of argon trimers in intense laser fields

    NASA Astrophysics Data System (ADS)

    Xie, Xiguo; Wu, Chengyin; Yuan, Zongqiang; Ye, Difa; Wang, Peng; Deng, Yongkai; Fu, Libin; Liu, Jie; Liu, Yunquan; Gong, Qihuang

    2015-08-01

    We have experimentally and theoretically studied the fragmentation dynamics of argon trimer (A r3) in intense laser fields. By coincidently measuring the momentum vectors, we obtained the emission geometry of the three fragmental ions produced in the three-body fragmentation process. In addition to the direct Coulomb explosion channels, we observed the indirect Coulomb explosion channels with Rydberg excitation. We have further developed a classical polyatomic molecular ensemble model, in which all interactions among electrons and nuclei are fully included, to simulate the fragmentation dynamics of argon trimer in intense laser fields. The experimental observations have been reproduced by the model calculation. The simulations show that the Rydberg excitation modifies the kinetic energy release as well as the emission geometry of fragmental ions during the explosion process. The study provides insight into the correlation dynamics of electrons and nuclei of many-body physics driven by intense laser fields.

  19. Exposure estimates based on broadband ELF magnetic field measurements versus the ICNIRP multiple frequency rule.

    PubMed

    Paniagua, Jesús M; Rufo, Montaña; Jiménez, Antonio; Pachón, Fernando T; Carrero, Julián

    2015-02-01

    The evaluation of exposure to extremely low-frequency (ELF) magnetic fields using broadband measurement techniques gives satisfactory results when the field has essentially a single frequency. Nevertheless, magnetic fields are in most cases distorted by harmonic components. This work analyses the harmonic components of the ELF magnetic field in an outdoor urban context and compares the evaluation of the exposure based on broadband measurements with that based on spectral analysis. The multiple frequency rule of the International Commission on Non-ionizing Radiation Protection (ICNIRP) regulatory guidelines was applied. With the 1998 ICNIRP guideline, harmonics dominated the exposure with a 55% contribution. With the 2010 ICNIRP guideline, however, the primary frequency dominated the exposure with a 78% contribution. Values of the exposure based on spectral analysis were significantly higher than those based on broadband measurements. Hence, it is clearly necessary to determine the harmonic components of the ELF magnetic field to assess exposure in urban contexts.

  20. Neuronal Cellular Responses to Extremely Low Frequency Electromagnetic Field Exposure: Implications Regarding Oxidative Stress and Neurodegeneration

    PubMed Central

    Reale, Marcella; Kamal, Mohammad A.; Patruno, Antonia; Costantini, Erica; D'Angelo, Chiara; Pesce, Miko; Greig, Nigel H.

    2014-01-01

    Neurodegenerative diseases comprise both hereditary and sporadic conditions characterized by an identifying progressive nervous system dysfunction and distinctive neuopathophysiology. The majority are of non-familial etiology and hence environmental factors and lifestyle play key roles in their pathogenesis. The extensive use of and ever increasing worldwide demand for electricity has stimulated societal and scientific interest on the environmental exposure to low frequency electromagnetic fields (EMFs) on human health. Epidemiological studies suggest a positive association between 50/60-Hz power transmission fields and leukemia or lymphoma development. Consequent to the association between EMFs and induction of oxidative stress, concerns relating to development of neurodegenerative diseases, such as Alzheimer disease (AD), have been voiced as the brain consumes the greatest fraction of oxygen and is particularly vulnerable to oxidative stress. Exposure to extremely low frequency (ELF)-EMFs are reported to alter animal behavior and modulate biological variables, including gene expression, regulation of cell survival, promotion of cellular differentiation, and changes in cerebral blood flow in aged AD transgenic mice. Alterations in inflammatory responses have also been reported, but how these actions impact human health remains unknown. We hence evaluated the effects of an electromagnetic wave (magnetic field intensity 1mT; frequency, 50-Hz) on a well-characterized immortalized neuronal cell model, human SH-SY5Y cells. ELF-EMF exposure elevated the expession of NOS and O2−, which were countered by compensatory changes in antioxidant catylase (CAT) activity and enzymatic kinetic parameters related to CYP-450 and CAT activity. Actions of ELF-EMFs on cytokine gene expression were additionally evaluated and found rapidly modified. Confronted with co-exposure to H2O2-induced oxidative stress, ELF-EMF proved not as well counteracted and resulted in a decline in CAT

  1. An electron of helium atom under a high-intensity laser field

    NASA Astrophysics Data System (ADS)

    Falaye, Babatunde James; Sun, Guo-Hua; Adepoju, Adenike Grace; Liman, Muhammed S.; Oyewumi, K. J.; Dong, Shi-Hai

    2017-02-01

    We scrutinize the behavior of eigenvalues of an electron in a helium (He) atom as it interacts with electric field directed along the z-axis and is exposed to linearly polarized intense laser field radiation. To achieve this, we freeze one electron of the He atom at its ionic ground state and the motion of the second electron in the ion core is treated via a more general case of screened Coulomb potential model. Using the Kramers-Henneberger (KH) unitary transformation, which is the semiclassical counterpart of the Block-Nordsieck transformation in the quantized field formalism, the squared vector potential that appears in the equation of motion is eliminated and the resultant equation is expressed in the KH frame. Within this frame, the resulting potential and the corresponding wave function are expanded in Fourier series and using Ehlotzky’s approximation, we obtain a laser-dressed potential to simulate intense laser field. By fitting the more general case of screened Coulomb potential model into the laser-dressed potential, and then expanding it in Taylor series up to O≤ft({{r}4},α 09\\right) , we obtain the solution (eigenvalues and wave function) of an electron in a He atom under the influence of external electric field and high-intensity laser field, within the framework of perturbation theory formalism. We found that the variation in frequency of laser radiation has no effect on the eigenvalues of a He electron for a particular electric field intensity directed along z-axis. Also, for a very strong external electric field and an infinitesimal screening parameter, the system is strongly bound. This work has potential application in the areas of atomic and molecular processes in external fields including interactions with strong fields and short pulses.

  2. The Inhibitory Effects of Static Magnetic Field on Escherichia coli from two Different Sources at Short Exposure Time

    PubMed Central

    Mousavian-Roshanzamir, Sofieh; Makhdoumi-Kakhki, Ali

    2017-01-01

    This study was intended to investigate the effectiveness of static magnetic field on the growth of Escherichia coli (E. coli) provided from two sources, the urine samples of patients with urinary tract infections and the reference strain E. coli ATCC 25922. Bacterial samples in Nutrient Broth were subjected to a range of magnetic intensities (2, 4, 6, 9, 14, 16, 18, and 20 mT) at various exposure times (0, 15, 30, 45, 60, 75, and 90 min). The survival rate was measured in the presence and absence of the magnetic field over time. The cell counts of uropathogenic E. coli did not statistically differed from those of the standard strain if exposed to the magnetic field. The fluctuation was observed in cell viabilities at different magnetic intensities below 18 mT. Both groups presented a significant decline in survival rate as exposed to 18 and 20 mT. PMID:28367473

  3. Interleukin-1β Can Reduce Manifestations of Delayed Effects of Prolonged Exposure to Low-Intensity γ-Radiation.

    PubMed

    Vorobyeva, N Yu; Grekhova, A K; Trubitsina, K Yu; Pchelka, A V; Rozhdestevenskiy, L M; Osipov, A N

    2016-02-01

    We showed that injection of IL-1β (Betaleukin) in a dose of 3 μg/kg 22 h before prolonged (21 h) exposure to low-intensity (10 mGy/min) γ-radiation in a dose of 12.6 Gy reduced the number of double-strand DNA breaks in murine spleen cells to the control level in 4 months after exposure and the number of double-strand DNA breaks induced by additional acute irradiation in a dose of 6 Gy. The results suggest that IL-1β can improve the efficiency of systems reducing the number of double-strand DNA breaks in murine spleen cells at delayed terms after exposure to prolonged low-intensity radiation.

  4. Study on cavitation behavior during high-intensity focused ultrasound exposure by using optical and ultrasonic imaging

    NASA Astrophysics Data System (ADS)

    Taguchi, Kei; Takagi, Ryo; Yasuda, Jun; Yoshizawa, Shin; Umemura, Shin-ichiro

    2016-07-01

    Cavitation bubbles are known to enhance the heating effect of high-intensity focused ultrasound (HIFU). In our previous study, the use of a “triggered HIFU” sequence consisting of a high-intensity pulse and a relatively low-intensity burst was proposed as an effective method to utilize the effect of cavitation bubbles. However, the duration of each component in the sequence has not been optimized. In this study, optical imaging was carried out to observe the behavior of cavitation bubbles in a gel phantom during the triggered HIFU exposure. Ultrasound imaging using the pulse inversion method was also conducted to detect the behavior of the bubbles. The results suggest that the oscillation of cavitation bubbles become inactive as the duration of HIFU burst exposure increases to the order of 10 ms. It was also suggested that ultrasonic imaging has potential use for detecting a change in the oscillation of cavitation bubbles for optimizing a triggered HIFU sequence.

  5. Estimating Individual Exposure to Malaria Using Local Prevalence of Malaria Infection in the Field

    PubMed Central

    Olotu, Ally; Fegan, Gregory; Wambua, Juliana; Nyangweso, George; Ogada, Edna; Drakeley, Chris; Marsh, Kevin; Bejon, Philip

    2012-01-01

    Background Heterogeneity in malaria exposure complicates survival analyses of vaccine efficacy trials and confounds the association between immune correlates of protection and malaria infection in longitudinal studies. Analysis may be facilitated by taking into account the variability in individual exposure levels, but it is unclear how exposure can be estimated at an individual level. Method and Findings We studied three cohorts (Chonyi, Junju and Ngerenya) in Kilifi District, Kenya to assess measures of malaria exposure. Prospective data were available on malaria episodes, geospatial coordinates, proximity to infected and uninfected individuals and residence in predefined malaria hotspots for 2,425 individuals. Antibody levels to the malaria antigens AMA1 and MSP1142 were available for 291 children from Junju. We calculated distance-weighted local prevalence of malaria infection within 1 km radius as a marker of individual's malaria exposure. We used multivariable modified Poisson regression model to assess the discriminatory power of these markers for malaria infection (i.e. asymptomatic parasitaemia or clinical malaria). The area under the receiver operating characteristic (ROC) curve was used to assess the discriminatory power of the models. Local malaria prevalence within 1 km radius and AMA1 and MSP1142 antibodies levels were independently associated with malaria infection. Weighted local malaria prevalence had an area under ROC curve of 0.72 (95%CI: 0.66–0.73), 0.71 (95%CI: 0.69–0.73) and 0.82 (95%CI: 0.80–0.83) among cohorts in Chonyi, Junju and Ngerenya respectively. In a small subset of children from Junju, a model incorporating weighted local malaria prevalence with AMA1 and MSP1142 antibody levels provided an AUC of 0.83 (95%CI: 0.79–0.88). Conclusion We have proposed an approach to estimating the intensity of an individual's malaria exposure in the field. The weighted local malaria prevalence can be used as individual marker of malaria

  6. The Effects of Exposure to Low Frequency Electromagnetic Fields on Male Fertility.

    PubMed

    Darbandi, Mahsa; Darbandi, Sara; Agarwal, Ashok; Henkle, Ralf; Sadeghi, Mohammad Reza

    2017-06-23

    Context • People are increasingly exposed to low frequency (LF) electromagnetic fields (EMFs), mainly from electricity distribution networks and electronic devices. Critics of this widespread exposure believe that it can have detrimental effects on the human body. On the other hand, many in vivo and in vitro studies have claimed that low frequency electromagnetic therapy can function as a form of alternative medicine and that therapists can treat disease by applying electromagnetic radiation or pulsed EMFs to the body or cells. It is not yet entirely clear, however, whether LF-EMF is beneficial or harmful. Objectives • This study aimed to examine the effects of LF-EMFs on men's reproductive functions, according to the types of waveform and the frequency and duration of exposure. Design • The study reviewed all available research, both human and animal, on the effects of LF-EMFs on male reproductive functions, covering the literature from January 1978 to June 2016. The documents were obtained from PubMed, Science Direct, and Google Scholar, and any article that was irrelevant or a duplicate was excluded. A total of 61 articles were found, and 27 articles were reviewed. Setting • This project was performed at the Avicenna Research Center (Tehran, Iran). Participants • Literature included human and animal studies conducted on rabbits, mice, rats, and boars. Intervention • Among these studies, any article that was irrelevant, a duplicate, or published with duplicate data was excluded. At the end, 27 articles were checked. Outcome Measures • Outcome measures included testing related to reproductive organ weights, reproductive endocrinal hormones, fetal development, and spermatogenesis as well as sperm motility, morphology, and vitality. Results • The reviewed studies provided contradictory results that were highly dependent on the exposure parameters, such as the shape and frequency of wave, intensity, duration, and timing of the exposure. Conclusions

  7. Assessment of physiotherapists' occupational exposure to radiofrequency electromagnetic fields from shortwave and microwave diathermy devices: a literature review.

    PubMed

    Shah, Syed Ghulam Sarwar; Farrow, Alexandra

    2013-01-01

    We reviewed studies reporting the strength of radiofrequency (RF) electromagnetic fields (EMF) in physiotherapists' occupational environment. Studies from academic journals published from January 1990 to June 2010 were identified in nine online bibliographic databases. EMF strength was compared with occupational exposure limits (OELs) recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). In the reviewed studies, EMFs were measured at different distances (range 0.2 m to 6 m) from the console of diathermy devices, electrodes, and cables. For continuous shortwave diathermy (CSWD) (27.12 megahertz, MHz), measurements of EMFs at < 1 m, 1 m, 1.1-1.5 m, and 2 m reported the maximum E field strength as 8197%, 1639%, 295%, and 69%, respectively, and the maximum H field strength as 6250%, 681%, 213%, and 56%, respectively, of the ICNIRP limits for E and H fields for occupational exposure. For pulsed shortwave diathermy (PSWD) (27.12 MHz), EMF measurements at < 1 m, 1 m, and, 1.1-1.5 m showed the maximum E field intensity as 1639%, 175%, and 32%, and the maximum H field strength as 1175%, 968%, and 28%, respectively, of the ICNIRP limits for E and H fields for occupational exposure. For microwave diathermy (MWD) (2.45 gigahertz, GHz), the maximum power density measured at < 1 m, 1 m, 1.1-1.5 m, and 2 m was 200%, <30%, 0.76%, and 0.82%, respectively, of the ICNIRP limit for occupational exposure. RF EMF emissions measured from continuous and pulsed electrotherapeutic diathermy devices may well be higher than OELs at specific distances, i.e., at 1 m, which is currently designated to be a safe distance for physiotherapists. The minimum safe distance for physiotherapists should be revised to at least 2 m for CSWD and 1.5 m for PSWD. The reviewed studies did not provide evidence of exceeding the ICNIRP's reference levels for occupational exposure at 1 m from MWD devices.

  8. Intensity Modulated Proton Therapy for Craniospinal Irradiation: Organ-at-Risk Exposure and a Low-Gradient Junctioning Technique

    SciTech Connect

    Stoker, Joshua B.; Grant, Jonathan; Zhu, X. Ronald; Pidikiti, Rajesh; Mahajan, Anita; Grosshans, David R.

    2014-11-01

    Purpose: To compare field junction robustness and sparing of organs at risk (OARs) during craniospinal irradiation (CSI) using intensity modulated proton therapy (IMPT) to conventional passively scattered proton therapy (PSPT). Methods and Materials: Ten patients, 5 adult and 5 pediatric patients, previously treated with PSPT-based CSI were selected for comparison. Anterior oblique cranial fields, using a superior couch rotation, and posterior spinal fields were used for IMPT planning. To facilitate low-gradient field junctioning along the spine, the inverse-planning IMPT technique was divided into 3 stages. Dose indices describing target coverage and normal tissue dose, in silico error modeling, and film dosimetry were used to assess plan quality. Results: Field junction robustness along the spine was improved using the staged IMPT planning technique, reducing the worst case impact of a 4-mm setup error from 25% in PSPT to <5% of prescription dose. This was verified by film dosimetry for clinical delivery. Exclusive of thyroid dose in adult patients, IMPT plans demonstrated sparing of organs at risk as good or better than PSPT. Coverage of the cribriform plate for pediatric (V95% [percentage of volume of the target receiving at least 95% of the prescribed dose]; 87 ± 11 vs 92 ± 7) and adult (V95%; 94 ± 7 vs 100 ± 1) patients and the clinical target in pediatric (V95%; 98 ± 2 vs 100 ± 1) and adult (V95%; 100 ± 1 vs 100 ± 1) patients for PSPT and IMPT plans, respectively, were comparable or improved. For adult patients, IMPT target dose inhomogeneity was increased, as determined by heterogeneity index (HI) and inhomogeneity coefficient (IC). IMPT lowered maximum spinal cord dose, improved spinal dose homogeneity, and reduced exposure to other OARs. Conclusions: IMPT has the potential to improve CSI plan quality and the homogeneity of intrafractional dose at match lines. The IMPT approach developed may also simplify treatments and reduce

  9. Repeated exposure attenuates the behavioral response of rats to static high magnetic fields

    PubMed Central

    Houpt, Thomas A.; Cassell, Jennifer A.; Hood, Alison; DenBleyker, Megan; Janowitz, Ilana; Mueller, Kathleen; Ortega, Breyda; Smith, James C.

    2010-01-01

    Exposure of rats to high strength static magnetic fields of 7 T or above has behavioral effects such as the induction of locomotor circling, the suppression of rearing, and the acquisition of conditioned taste aversion (CTA). To determine if habituation occurs across magnetic field exposures, rats were pre-exposed two times to a 14 T static magnetic field for 30 min on two consecutive days; on the third day, rats were given access to a novel 0.125% saccharin prior to a third 30-min exposure to the 14 T magnetic field. Compared to sham-exposed rats, pre-exposed rats showed less locomotor circling and an attenuated CTA. Rearing was suppressed in all magnet-exposed groups regardless of pre-exposure, suggesting that the suppression of rearing is more sensitive than other behavioral responses to magnet exposure. Habituation was also observed when rats under went pre-exposures at 2–3 hour intervals on a single day. Components of the habituation were also long lasting; a diminished circling response was observed when rats were exposed to magnetic field 36 days after 2 pre-exposures. To control for possible effects of unconditioned stimulus pre-exposure, rats were also tested in a similar experimental design with two injections of LiCl prior to the pairing of saccharin with a third injection of LiCl. Pre-exposure to LiCl did not attenuate the LiCl-induced CTA, suggesting that 2 pre-exposures to an unconditioned stimulus are not sufficient to explain the habituation to magnet exposure. Because the effects of magnetic field exposure are dependent on an intact vestibular apparatus, and because the vestibular system can habituate to many forms of perturbation, habituation to magnetic field exposure is consistent with mediation of magnetic field effects by the vestibular system. PMID:20045422

  10. Determination of the duty cycle of WLAN for realistic radio frequency electromagnetic field exposure assessment.

    PubMed

    Joseph, Wout; Pareit, Daan; Vermeeren, Günter; Naudts, Dries; Verloock, Leen; Martens, Luc; Moerman, Ingrid

    2013-01-01

    Wireless Local Area Networks (WLANs) are commonly deployed in various environments. The WLAN data packets are not transmitted continuously but often worst-case exposure of WLAN is assessed, assuming 100% activity and leading to huge overestimations. Actual duty cycles of WLAN are thus of importance for time-averaging of exposure when checking compliance with international guidelines on limiting adverse health effects. In this paper, duty cycles of WLAN using Wi-Fi technology are determined for exposure assessment on large scale at 179 locations for different environments and activities (file transfer, video streaming, audio, surfing on the internet, etc.). The median duty cycle equals 1.4% and the 95th percentile is 10.4% (standard deviation SD = 6.4%). Largest duty cycles are observed in urban and industrial environments. For actual applications, the theoretical upper limit for the WLAN duty cycle is 69.8% and 94.7% for maximum and minimum physical data rate, respectively. For lower data rates, higher duty cycles will occur. Although counterintuitive at first sight, poor WLAN connections result in higher possible exposures. File transfer at maximum data rate results in median duty cycles of 47.6% (SD = 16%), while it results in median values of 91.5% (SD = 18%) at minimum data rate. Surfing and audio streaming are less intensively using the wireless medium and therefore have median duty cycles lower than 3.2% (SD = 0.5-7.5%). For a specific example, overestimations up to a factor 8 for electric fields occur, when considering 100% activity compared to realistic duty cycles.

  11. A Dosimetric Evaluation of Conventional Helmet Field Irradiation Versus Two-Field Intensity-Modulated Radiotherapy Technique

    SciTech Connect

    Yu, James B.; Shiao, Stephen L.; Knisely, Jonathan . E-mail: jonathan.knisely@yale.edu

    2007-06-01

    Purpose: To compare dosimetric differences between conventional two-beam helmet field irradiation (external beam radiotherapy, EBRT) of the brain and a two-field intensity-modulated radiotherapy (IMRT) technique. Methods and Materials: Ten patients who received helmet field irradiation at our institution were selected for study. External beam radiotherapy portals were planned per usual practice. Intensity-modulated radiotherapy fields were created using the identical field angles as the EBRT portals. Each brain was fully contoured along with the spinal cord to the bottom of the C2 vertebral body. This volume was then expanded symmetrically by 0.5 cm to construct the planning target volume. An IMRT plan was constructed using uniform optimization constraints. For both techniques, the nominal prescribed dose was 3,000 cGy in 10 fractions of 300 cGy using 6-MV photons. Comparative dose-volume histograms were generated for each patient and analyzed. Results: Intensity-modulated radiotherapy improved dose uniformity over EBRT for whole brain radiotherapy. The mean percentage of brain receiving >105% of dose was reduced from 29.3% with EBRT to 0.03% with IMRT. The mean maximum dose was reduced from 3,378 cGy (113%) for EBRT to 3,162 cGy (105%) with IMRT. The mean percent volume receiving at least 98% of the prescribed dose was 99.5% for the conventional technique and 100% for IMRT. Conclusions: Intensity-modulated radiotherapy reduces dose inhomogeneity, particularly for the midline frontal lobe structures where hot spots occur with conventional two-field EBRT. More study needs to be done addressing the clinical implications of optimizing dose uniformity and its effect on long-term cognitive function in selected long-lived patients.

  12. Effects function analysis of ELF magnetic field exposure in the electric utility work environment.

    PubMed

    Zhang, J; Nair, I; Sahl, J

    1997-01-01

    The incomplete understanding of the relation between power-frequency fields and biological responses raises problems in defining an appropriate metric for exposure assessment and epidemiological studies. Based on evidence from biological experiments, one can define alternative metrics or effects functions that embody the relationship between field exposure patterns and hypothetical health effects. In this paper, we explore the application of the "effects function" approach to occupational exposure data. Our analysis provides examples of exposure assessments based on a range of plausible effects functions. An EMDEX time series data set of ELF frequency (40-800 Hz) magnetic field exposure measurements for electric utility workers was analyzed with several statistical measures and effects functions: average field strength, combination of threshold and exposure duration, and field strength changes. Results were compared for eight job categories: electrician, substation operator, machinist, welder, plant operator, lineman/splicer, meter reader, and clerical. Average field strength yields a different ranking for these job categories than the ranks obtained using other biologically plausible effects functions. Whereas the group of electricians has the highest exposure by average field strength, the group of substation operators has the highest ranking for most of the other effects functions. Plant operators rank highest in the total number of field strength changes greater than 1 microT per hour. The clerical group remains at the lowest end for all of these effects functions. Our analysis suggests that, although average field strength could be used as a surrogate of field exposure for simply classifying exposure into "low" and "high," this summary measure may be misleading in the relative ranking of job categories in which workers are in "high" fields. These results indicate the relevance of metrics other than average field strength in occupational exposure assessment and

  13. Development of a source-exposure matrix for occupational exposure assessment of electromagnetic fields in the INTEROCC study

    PubMed Central

    Vila, Javier; Bowman, Joseph D; Figuerola, Jordi; Moriña, David; Kincl, Laurel; Richardson, Lesley; Cardis, Elisabeth

    2017-01-01

    Introduction To estimate occupational exposures to electromagnetic fields (EMF) for the INTEROCC study, a database of source-based measurements extracted from published and unpublished literature resources had been previously constructed. The aim of the current work was to summarize these measurements into a source-exposure matrix (SEM), accounting for their quality and relevance. Methods A novel methodology for combining available measurements was developed, based on order statistics and log-normal distribution characteristics. Arithmetic and geometric means, and estimates of variability and maximum exposure were calculated by EMF source, frequency band and dosimetry type. Mean estimates were weighted by our confidence on the pooled measurements. Results The SEM contains confidence-weighted mean and maximum estimates for 312 EMF exposure sources (from 0 Hz to 300 GHz). Operator position geometric mean electric field levels for RF sources ranged between 0.8 V/m (plasma etcher) and 320 V/m (RF sealer), while magnetic fields ranged from 0.02 A/m (speed radar) to 0.6 A/m (microwave heating). For ELF sources, electric fields ranged between 0.2 V/m (electric forklift) and 11,700 V/m (HVTL-hotsticks), while magnetic fields ranged between 0.14 μT (visual display terminals) and 17 μT (TIG welding). Conclusion The methodology developed allowed the construction of the first EMF-SEM and may be used to summarize similar exposure data for other physical or chemical agents. PMID:27827378

  14. Determination of the electric field intensity and space charge density versus height prior to triggered lightning

    NASA Astrophysics Data System (ADS)

    Biagi, C. J.; Uman, M. A.; Gopalakrishnan, J.; Hill, J. D.; Rakov, V. A.; Ngin, T.; Jordan, D. M.

    2011-08-01

    We infer the vertical profiles of space charge density and electric field intensity above ground by comparing modeling and measurements of the ground-level electric field changes caused by elevating grounded lightning-triggering wires. The ground-level electric fields at distances of 60 m and 350 m were measured during six wire launches that resulted in triggered lightning. The wires were launched when ground-level electric fields ranged from 3.2 to 7.6 kV m-1 and the triggering heights ranged from 123 to 304 m. From wire launch time to lightning initiation time, the ground-level electric field reduction at 60 m ranged from 2.2 to 3.4 kV m-1, with little ground-level electric field reduction being observed at 350 m. We observed that the triggering heights were inversely proportional to the ground-level electric field when the wires were launched. Our Poisson equation solver simulates the ground-level electric field changes as the grounded wires extend in assumed vertically varying profiles of space charge density and electric field intensity. Our model reproduces the measured ground-level electric field changes when the assumed space charge density decays exponentially with altitude, with ground-level charge densities between 1.5 and 7 nC m-3, space charge exponential decay height constants ranging from 67 to 200 m, and uniform electric field intensities far above the space charge layer ranging from 20 to 60 kV m-1. Our model predicts typical charge densities on the wires of some tens of μC m-1 with milliampere-range currents flowing into the wires from ground to supply the wire charge.

  15. Induction of adaptive response: pre-exposure of mice to 900 MHz radiofrequency fields reduces hematopoietic damage caused by subsequent exposure to ionising radiation.

    PubMed

    Cao, Yi; Xu, Qian; Jin, Zong-Da; Zhou, Zhen; Nie, Ji-Hua; Tong, Jian

    2011-07-01

    To investigate whether an adaptive response can be induced in mice which were pre-exposed to 900 MHz radiofrequency fields. Adult male Kunming mice were exposed to 900 MHz radiofrequency fields (RF) at power intensities of 12, 120 and 1200 μW/cm(2) for 1 h/day for 14 days and then subjected to whole body gamma-irradiation. The results were compared with those in unexposed control animals and those exposed to gamma-irradiation alone (without pre-exposure to RF). The extent of survival and hematopoietic tissue damage (assessed in the form of nucleated colony forming cells in the bone marrow and colony forming cells in the spleen of lethally irradiated 'recipient' mice) as well as the expression of cell cycle-related genes were investigated. The results indicated a significant increase in survival time, reduction in the hematopoietic tissue damage in RF pre-exposed mice which were gamma-irradiated (as compared with those exposed to gamma-radiation alone). This was accompanied by significantly increased expression of cell cycle-related genes, namely, cyclin-D1, cyclin-E, cyclin-DK4 and cyclin-DK2 in hematopoietic cells. Pre-exposure of mice to 900 MHz radiofrequency fields has resulted in a significant reduction in hematopoietic damage caused by subsequent exposure to ionising radiation. This phenomenon appears to be similar to that of the 'adaptive response' which is well documented in scientific literature.

  16. The effect of magnetic field intensity and treatment time on graphene / epoxy composites’ fracture toughness

    NASA Astrophysics Data System (ADS)

    Tian, Z. Q.; Zhang, L.; Fu, S.; Yuan, R. H.; Dong, Z. W.; Ren, X. M.

    2016-07-01

    The effect of the intensity of the magnetic field and the treatment time on the fracture toughness of graphene/epoxy composites is researched. Also, the mechanism of the effect of the magnetic field on the fracture toughness of graphene/epoxy composites and a method to improve the impact resistance is explored. Then, three-point bending tests are employed to characterize the fracture toughness of graphene/epoxy composite. The results show that the intervention of magnetic field could induce GNS to generated orientation arrangement, improving the fracture toughness of the graphene/epoxy composite. When the intensity of the magnetic field was increased, the growth rate of the fracture toughness slowed. However, when 2T magnetic was used to synthetically process the material, and when the processing time was less than 50 min, the fracture toughness of the composite material increased significantly.

  17. Intraband optical absorption in a single quantum ring: Hydrostatic pressure and intense laser field effects

    NASA Astrophysics Data System (ADS)

    Barseghyan, M. G.

    2016-11-01

    The intraband optical absorption in GaAs/Ga0.7Al0.3As two-dimensional single quantum ring is investigated. Considering the combined effects of hydrostatic pressure and intense laser field the energy of the ground and few excited states has been found using the effective mass approximation and exact diagonalization technique. The energies of these states and the corresponding threshold energy of the intraband optical transitions are examined as a function of hydrostatic pressure for the different values of the laser field parameter. We also investigated the dependencies of the intraband optical absorption coefficient as a function of incident photon energy for different values of hydrostatic pressure and laser field parameter. It is found that the effects of hydrostatic pressure and intense laser field lead to redshift and blueshift of the intraband optical spectrum respectively.

  18. The atom in an intense optical field (2nd revised and enlarged edition)

    NASA Astrophysics Data System (ADS)

    Delone, N. B.; Krainov, V. P.

    The basic features characterizing multiphoton processes are examined, and descriptions are given of such phenomena as the multiphoton ionization of atoms, multiphoton resonance, and the perturbation of the bound-state spectrum in atoms in an optical field. The design of an experiment for measuring the interaction of laser radiation with atoms is proposed. Particular attention is given to nonlinear atomic susceptibilities, the effect of multifrequency laser radiation, and the behavior of highly excited atoms in an intense optical field.

  19. Relation of the green coronal line intensity to sunspot areas and magnetic fields of different scales

    NASA Astrophysics Data System (ADS)

    Badalyan, O. G.; Bludova, N. G.

    2014-07-01

    The intensity of Fe XIV 530.3-nm green coronal line is compared quantitatively with the strength of magnetic fields of small and large scales and also with total sunspot areas for 1977-2001. A degree of similarity of appropriate synoptic maps is evaluated using correlation analysis. The green line intensity maps are constructed from data of its daily monitoring. Strengths of magnetic fields are calculated in a potential approximation using the photosphere observations of Wilcox Solar Observatory for a distance of 1.1 The calculations are performed separately for fields of large and small spatial scales. The total area of sunspots is obtained using data from the Greenwich Catalogue and its continuation by USAF/NOAA. The correlation has been calculated for the aggregate of areas (with a size of 20° in latitude and 30° in longitude) coinciding spatially on all maps. It is found that the most correlation between the green line intensity and coronal fields of small scales is observed in a zone of 0°-20°. The correlation with total sunspot areas (i.e., with local fields at the photosphere level) is substantially less here. In the higher-latitude zone 20°-40°, correlation of the green-line intensity with spot areas and small-scale coronal fields decreases. The large-scale fields have little influence on the green-line emission in the spot-formation zone. These results are the evidence of a complex nature of the effect of different-scale fields, arising as a result of dynamo activity in the subsurface (leptocline) and deep-lying (tachocline) layers of the convective zone, on the processes of the Sun's corona heating and green coronal line emission.

  20. Disorder fingerprint: Intensity distributions in the near field of random media

    NASA Astrophysics Data System (ADS)

    Naraghi, R. Rezvani; Sukhov, S.; Dogariu, A.

    2016-11-01

    The structural morphology of complex dielectric media determines their functionalities by driving the statistical properties of the electromagnetic fields. Our controlled experiments and full electromagnetic calculations that go beyond common dipolar approximations demonstrate that the specific characteristics of disorder lead to non-Rayleigh statistics of detected intensity, which can be directly accessed in the near field of random media and can be unambiguously related to the short-range correlations of disorder.

  1. Marine stratocumulus cloud parameters from GOES during the 1987 FIRE intensive field observation period

    NASA Technical Reports Server (NTRS)

    Young, David F.; Heck, Patrick W.; Minnis, Patrick; Harrison, Edwin F.

    1989-01-01

    GOES was used to perform the Marine Stratocumulus Intensive Field Observations (IFO) from June 29 to July 19, 1987. Preliminary results of an analysis of GOES data covering most of the IFO period are discussed. The large-scale cloud-field characteristics are derived, and then related to a longer period of measurements and to surface observations. Some preliminary point measurements taken from the surface are compared to regional-scale cloud parameters derived from satellite radiances.

  2. The Effects of Didactic Classroom Instruction versus Field Exposure on Career Maturity.

    ERIC Educational Resources Information Center

    Yongue, Imogene T.; And Others

    1981-01-01

    Tested two types of career training (field exposure and didactic classroom) to determine which is more effective in bringing about the development of career maturity. Results indicated that field exposure career training is an effective method to increase career maturity. (Author)

  3. Isoprene emission aids recovery of photosynthetic performance in transgenic Nicotiana tabacum following high intensity acute UV-B exposure.

    PubMed

    Centritto, Mauro; Haworth, Matthew; Marino, Giovanni; Pallozzi, Emanuele; Tsonev, Tsonko; Velikova, Violeta; Nogues, Isabel; Loreto, Francesco

    2014-09-01

    Isoprene emission by terrestrial plants is believed to play a role in mitigating the effects of abiotic stress on photosynthesis. Ultraviolet-B light (UV-B) induces damage to the photosynthetic apparatus of plants, but the role of isoprene in UV-B tolerance is poorly understood. To investigate this putative protective role, we exposed non-emitting (NE) control and transgenic isoprene emitting (IE) Nicotiana tabacum (tobacco) plants to high intensity UV-B exposure. Methanol emissions increased with UV-B intensity, indicating oxidative damage. However, isoprene emission was unaffected during exposure to UV-B radiation, but declined in the 48 h following UV-B treatment at the highest UV-B intensities of 9 and 15 Wm(-2). Photosynthesis and the performance of photosystem II (PSII) declined to similar extents in IE and NE plants following UV-B exposure, suggesting that isoprene emission did not ameliorate the immediate impact of UV-B on photosynthesis. However, after the stress, photosynthesis and PSII recovered in IE plants, which maintained isoprene formation, but not in NE plants. Recovery of IE plants was also associated with elevated antioxidant levels and cycling; suggesting that both isoprene formation and antioxidant systems contributed to reinstating the integrity and functionality of cellular membranes and photosynthesis following exposure to excessive levels of UV-B radiation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  4. Spontaneous transitions in atomic system in the presence of high-intensity laser field

    NASA Astrophysics Data System (ADS)

    Bogatskaya, Anna; Volkova, Ekaterina; Popov, Alexander

    2016-10-01

    A new approach to the study of the spontaneous emission of the quantum system driven by a high-intensity laser field is developed. This approach is based on the accurate consideration of quantum system interaction with vacuum quantized field modes in the first order of perturbation theory, while the intense laser field is considered classically beyond the perturbation theory which allows to observe any-order stimulated processes governed by classical field. The proposed approach is applied to the study of a number of quantum systems in intense laser field. The obtained data are compared with those obtained in the frames of semiclassical approximation typically used for analyzing of the strong-field dynamic. It is found that the applicability of the semiclassical approach is strictly limited. It is valid for calculation of transitions to the initially populated state only if the population of this state is close to unity during the pulse and in the after-pulse regime. If its population is depleted, the semiclassical approach fails.

  5. Effects of 900 MHz electromagnetic fields exposure on cochlear cells' functionality in rats: evaluation of distortion product otoacoustic emissions.

    PubMed

    Galloni, Paolo; Lovisolo, Giorgio Alfonso; Mancini, Sergio; Parazzini, Marta; Pinto, Rosanna; Piscitelli, Marta; Ravazzani, Paolo; Marino, Carmela

    2005-10-01

    In recent years, the widespread use of mobile phones has been accompanied by public debate about possible adverse consequences on human health. The auditory system is a major target of exposure to electromagnetic fields (EMF) emitted by cellular telephones; the aim of this study was the evaluation of possible effects of cellular phone-like emissions on the functionality of rat's cochlea. Distortion Products OtoAcoustic Emission (DPOAE) amplitude was selected as cochlea's outer hair cells (OHC) status indicator. A number of protocols, including different frequencies (the lower ones in rat's cochlea sensitivity spectrum), intensities and periods of exposure, were used; tests were carried out before, during and after the period of treatment. No significant variation due to exposure to microwaves has been evidenced.

  6. 14 CFR 25.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1317 High... that performs a function whose failure would significantly reduce the capability of the airplane or...

  7. 14 CFR 27.1317 - High-intensity Radiated Fields (HIRF) Protection.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-intensity Radiated Fields (HIRF... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1317 High... performs a function whose failure would significantly reduce the capability of the rotorcraft or...

  8. Permanent-magnet Faraday isolator with the field intensity of 25 kOe

    SciTech Connect

    Mironov, E A; Snetkov, I L; Voitovich, A V; Palashov, O V

    2013-08-31

    A Faraday isolator with a single magneto-optical element is constructed and experimentally tested. It provides the isolation ratio of 30 dB at an average laser radiation power of 650 W. These parameters are obtained by increasing the field intensity in the magnetic system of the isolator and employing a low-absorption magneto-optical element. (elements of laser devices)

  9. High-intensity pulsed electric field variables affecting Staphylococcus aureus inoculated in milk.

    PubMed

    Sobrino-López, A; Raybaudi-Massilia, R; Martín-Belloso, O

    2006-10-01

    Staphylococcus aureus is an important milk-related pathogen that is inactivated by high-intensity pulsed electric fields (HIPEF). In this study, inactivation of Staph. aureus suspended in milk by HIPEF was studied using a response surface methodology, in which electric field intensity, pulse number, pulse width, pulse polarity, and the fat content of milk were the controlled variables. It was found that the fat content of milk did not significantly affect the microbial inactivation of Staph. aureus. A maximum value of 4.5 log reductions was obtained by applying 150 bipolar pulses of 8 mus each at 35 kV/cm. Bipolar pulses were more effective than those applied in the monopolar mode. An increase in electric field intensity, pulse number, or pulse width resulted in a drop in the survival fraction of Staph. aureus. Pulse widths close to 6.7 micros lead to greater microbial death with a minimum number of applied pulses. At a constant treatment time, a greater number of shorter pulses achieved better inactivation than those treatments performed at a lower number of longer pulses. The combined action of pulse number and electric field intensity followed a similar pattern, indicating that the same fraction of microbial death can be reached with different combinations of the variables. The behavior and relationship among the electrical variables suggest that the energy input of HIPEF processing might be optimized without decreasing the microbial death.

  10. Variations in the intensity of the geomagnetic field in Siberia during the last 13000 years

    NASA Astrophysics Data System (ADS)

    Nachasova, I. E.; Burakov, K. S.; Pilipenko, O. V.

    2015-01-01

    The thermal magnetization of the samples from the archaeological sites in Siberia is studied. The magnetization of the collected samples was studied using the authors' modification of the Thellier method amended by the magnetic anisotropy and chemical alterations. Resulting from the study of the burned material from the Kazachka site, the time series of the geomagnetic field intensity in Siberia spanning the time interval from 10000 to 1000 B.C. is obtained. These data are unique in terms of the duration and representativeness. For the first time, the main variation in the intensity of the geomagnetic field is traced by studying the magnetization of the samples from a single archeological site. The pattern of the variations in the intensity of the geomagnetic field in Siberia from 11000 B.C. to 2000 A.D., which is reconstructed from the data of the Kazachka, Ust-Karenga, and some other sites of Cis-Baikalia, indicates that the characteristics time of the long-period oscillation in the intensity of the geomagnetic field is about 8000 years. It also suggests the existence of rapid variations superimposed on the main oscillation.

  11. Electromagnetic Confined Plasma Target for Interaction Studies with Intense Laser Fields

    SciTech Connect

    Zielbauer, B; Ursescu, U; Trotsenko, S; Spillmann, U; Schuch, R; Stohlker, T; Kuhl, T; Borneis, S; Schenkel, T; McDonald, J; Schneider, D

    2006-08-09

    The paper describes a novel application of an electron beam ion trap as a plasma target facility for intense laser-plasma interaction studies. The low density plasma target ({approx}10{sup 13}/cm{sup 3}) is confined in a mobile cryogenic electromagnetic charged particle trap, with the magnetic confinement field of 1-3T maintained by a superconducting magnet. Ion plasmas for a large variety of ion species and charge states are produced and maintained within the magnetic field and the space charge of an energetic electron beam in the ''Electron Beam Ion Trap'' (EBIT) geometry. Intense laser beams (optical lasers, x-ray lasers and upcoming ''X-Ray Free Electron Lasers'' (XFEL)) provide strong time varying electromagnetic fields (>10{sup 12} V/cm in femto- to nano-sec pulses) for interactions with electromagnetically confined neutral/non-neutral plasmas. The experiments are aimed to gain understanding of the effects of intense photon fields on ionization/excitation processes, the ionization balance, as well as photon polarization effects. First experimental scenarios and tests with an intense laser that utilize the ion plasma target are outlined.

  12. Oxygen consumption of zooplankton as affected by laboratory and field Cadmium exposures. [None

    SciTech Connect

    Kettle, W.D.; deNoyelles, F. Jr.; Lei, C.H.

    1980-10-01

    Virtually none of the many studies of the responses of aquatic organisms to heavy metals has involved organism response to heavy metals under natural, whole system exposure. The ability of laboratory studies to simulate and predict actual field conditions and responses remains questionable. The effects of cadmium exposure on zooplankton has been measured in laboratory studies and in enclosures placed in the field. However, studies involving zooplankton subjected to field exposure of cadmium are lacking. The objectives of this experiment were to measure oxygen consumption, survivorship, and reproduction of Daphnia pulex and Simocephalus serrulatus in response to low level cadmium exposure, in both laboratory and field situations. This design makes possible the comparisons of 1) laboratory and field exposures, and 2) responses of 2 common freshwater zooplankton species.

  13. Data-Model Comparisons of Photoelectron Flux Intensities on the Strong Crustal Field Lines at Mars

    NASA Astrophysics Data System (ADS)

    Liemohn, Michael; Trantham, Matthew; Mitchell, David

    2010-05-01

    This study quantifies the factors controlling photoelectron fluxes on strong crustal field lines in the Martian ionosphere. Using data from Mars Global Surveyor's Magnetometer and Electron Reflectometer instruments, dayside electron populations near the strong crustal fields in the southern hemisphere are analyzed versus various controlling parameters. These parameters include a Mars F10.7 proxy, a solar wind pressure proxy, local solar zenith angle, magnetic elevation angle, magnetic field strength. It was found that solar EUV radiation (corrected for solar zenith angle and the Mars-Sun distance) has the strongest influence on the photoelectron fluxes, and during different time periods this radiation has a stronger influence than at others times. Second, fluxes show a slight enhancement when the magnetic elevation angle is near zero degrees (horizontal field lines). Finally, other parameters, such as pressure and magnetic field strength, seem to have no major influence. These measurement-based results are then compared against numerical modeling flux intensities to quantify the physical mechanisms behind the observed relationships. The numerical code used for this study is our superthermal electron transport model, which solves for the electric distribution function along a magnetic field line. The code includes the influence of a variable magnetic field strength, pitch angle scattering and mirror trapping, and collisional energy cascading. The influence of solar EUV flux, atmospheric composition, solar wind dynamic pressure, and the local magnetic field are systematically investigated with this code to understand why some of these parameters have a strong influence on photoelectron flux intensity while others do not.

  14. The Energy Metabolism in Caenorhabditis elegans under The Extremely Low-Frequency Electromagnetic Field Exposure

    PubMed Central

    Shi, Zhenhua; Yu, Hui; Sun, Yongyan; Yang, Chuanjun; Lian, Huiyong; Cai, Peng

    2015-01-01

    A literal mountain of documentation generated in the past five decades showing unmistakable health hazards associated with extremely low-frequency electromagnetic fields (ELF-EMFs) exposure. However, the relation between energy mechanism and ELF-EMF exposure is poorly understood. In this study, Caenorhabditis elegans was exposed to 50 Hz ELF-EMF at intensities of 0.5, 1, 2, and 3 mT, respectively. Their metabolite variations were analyzed by GC-TOF/MS-based metabolomics. Although minimal metabolic variations and no regular pattern were observed, the contents of energy metabolism-related metabolites such as pyruvic acid, fumaric acid, and L-malic acid were elevated in all the treatments. The expressions of nineteen related genes that encode glycolytic enzymes were analyzed by using quantitative real-time PCR. Only genes encoding GAPDH were significantly upregulated (P < 0.01), and this result was further confirmed by western blot analysis. The enzyme activity of GAPDH was increased (P < 0.01), whereas the total intracellular ATP level was decreased. While no significant difference in lifespan, hatching rate and reproduction, worms exposed to ELF-EMF exhibited less food consumption compared with that of the control (P < 0.01). In conclusion, C. elegans exposed to ELF-EMF have enhanced energy metabolism and restricted dietary, which might contribute to the resistance against exogenous ELF-EMF stress. PMID:25683579

  15. The Energy Metabolism in Caenorhabditis elegans under The Extremely Low-Frequency Electromagnetic Field Exposure

    NASA Astrophysics Data System (ADS)

    Shi, Zhenhua; Yu, Hui; Sun, Yongyan; Yang, Chuanjun; Lian, Huiyong; Cai, Peng

    2015-02-01

    A literal mountain of documentation generated in the past five decades showing unmistakable health hazards associated with extremely low-frequency electromagnetic fields (ELF-EMFs) exposure. However, the relation between energy mechanism and ELF-EMF exposure is poorly understood. In this study, Caenorhabditis elegans was exposed to 50 Hz ELF-EMF at intensities of 0.5, 1, 2, and 3 mT, respectively. Their metabolite variations were analyzed by GC-TOF/MS-based metabolomics. Although minimal metabolic variations and no regular pattern were observed, the contents of energy metabolism-related metabolites such as pyruvic acid, fumaric acid, and L-malic acid were elevated in all the treatments. The expressions of nineteen related genes that encode glycolytic enzymes were analyzed by using quantitative real-time PCR. Only genes encoding GAPDH were significantly upregulated (P < 0.01), and this result was further confirmed by western blot analysis. The enzyme activity of GAPDH was increased (P < 0.01), whereas the total intracellular ATP level was decreased. While no significant difference in lifespan, hatching rate and reproduction, worms exposed to ELF-EMF exhibited less food consumption compared with that of the control (P < 0.01). In conclusion, C. elegans exposed to ELF-EMF have enhanced energy metabolism and restricted dietary, which might contribute to the resistance against exogenous ELF-EMF stress.

  16. The Energy Metabolism in Caenorhabditis elegans under The Extremely Low-Frequency Electromagnetic Field Exposure.

    PubMed

    Shi, Zhenhua; Yu, Hui; Sun, Yongyan; Yang, Chuanjun; Lian, Huiyong; Cai, Peng

    2015-02-16

    A literal mountain of documentation generated in the past five decades showing unmistakable health hazards associated with extremely low-frequency electromagnetic fields (ELF-EMFs) exposure. However, the relation between energy mechanism and ELF-EMF exposure is poorly understood. In this study, Caenorhabditis elegans was exposed to 50 Hz ELF-EMF at intensities of 0.5, 1, 2, and 3 mT, respectively. Their metabolite variations were analyzed by GC-TOF/MS-based metabolomics. Although minimal metabolic variations and no regular pattern were observed, the contents of energy metabolism-related metabolites such as pyruvic acid, fumaric acid, and L-malic acid were elevated in all the treatments. The expressions of nineteen related genes that encode glycolytic enzymes were analyzed by using quantitative real-time PCR. Only genes encoding GAPDH were significantly upregulated (P < 0.01), and this result was further confirmed by western blot analysis. The enzyme activity of GAPDH was increased (P < 0.01), whereas the total intracellular ATP level was decreased. While no significant difference in lifespan, hatching rate and reproduction, worms exposed to ELF-EMF exhibited less food consumption compared with that of the control (P < 0.01). In conclusion, C. elegans exposed to ELF-EMF have enhanced energy metabolism and restricted dietary, which might contribute to the resistance against exogenous ELF-EMF stress.

  17. Prenatal exposures to LTP-patterned magnetic fields: quantitative effects on specific limbic structures and acquisition of contextually conditioned fear.

    PubMed

    Whissell, P D; Tsang, E W; Mulligan, B P; Persinger, M A

    2009-01-01

    Weak (<1 microT) complex magnetic fields (CMFs) may exert their behavioral influences through the hippocampus by resonating by accident or design with intrinsic electrical patterns. Rats were exposed prenatally to one of four intensities of a CMF (either <5 nanoTesla [nT], 10-50 nT, 50-500 nT, or 500-1000 nT) designed to interact with the process of Long-Term Potentiation (LTP) in the hippocampus. Rats then underwent testing in the forced swim, open field, and fear-conditioning procedures. The cell densities of all amygdaloid nuclei, specific hypothalamic structures, and the major regions of the hippocampus were quantified. Results showed that acquisition of conditioned fear was strongly inhibited in animals exposed to LTP-CMFs. Rats exposed to intensities above 10 nT showed decreased cell density in the CA2 fields of the hippocampus; more neurons were present in the CA1 fields of rats exposed to the 10-50 nT intensities compared to all other groups. A decrease in cell density in the medial preoptic nucleus was linearly dependent on field intensity. In the forced-swim test, swimming was decreased in rats that had been exposed to low (10-50 nT) and medium intensity (50-500 nT) LTP-CMFs in a manner consistent with monoamine modulation. In the open field, exposed rats were indistinguishable from controls. These findings support the hypothesis that continuous exposure during prenatal development to CMFs designed to simulate intrinsic LTP within the hippocampus can affect adult behaviors specific to this structure and produce quantitative alterations in neuronal density.

  18. ELF magnetic field exposure system with feedback-controlled disturbance rejection

    SciTech Connect

    Wang, P.K.C.

    1997-06-01

    Extremely low-frequency (ELF) magnetic field exposure systems are usually subject to field disturbances induced by external sources. Here, a method for designing a feedback control system for canceling the effect of external ELF magnetic field disturbances on the magnetic field over the exposure area is presented. This method was used in the design of a feedback-controlled exposure system for an inverted microscope stage. The effectiveness of the proposed feedback control system for disturbance rejection was verified experimentally and by means of computer simulation.

  19. Does Exposure to a Radiofrequency Electromagnetic Field Modify Thermal Preference in Juvenile Rats?

    PubMed Central

    Pelletier, Amandine; Delanaud, Stéphane; de Seze, René; Bach, Véronique; Libert, Jean-Pierre; Loos, Nathalie

    2014-01-01

    Some studies have shown that people living near a mobile phone base station may report sleep disturbances and discomfort. Using a rat model, we have previously shown that chronic exposure to a low-intensity radiofrequency electromagnetic field (RF-EMF) was associated with paradoxical sleep (PS) fragmentation and greater vasomotor tone in the tail. Here, we sought to establish whether sleep disturbances might result from the disturbance of thermoregulatory processes by a RF-EMF. We recorded thermal preference and sleep stage distribution in 18 young male Wistar rats. Nine animals were exposed to a low-intensity RF-EMF (900 MHz, 1 V.m−1) for five weeks and nine served as non-exposed controls. Thermal preference was assessed in an experimental chamber comprising three interconnected compartments, in which the air temperatures (Ta) were set to 24°C, 28°C and 31°C. Sleep and tail skin temperature were also recorded. Our results indicated that relative to control group, exposure to RF-EMF at 31°C was associated with a significantly lower tail skin temperature (−1.6°C) which confirmed previous data. During the light period, the exposed group preferred to sleep at Ta = 31°C and the controls preferred Ta = 28°C. The mean sleep duration in exposed group was significantly greater (by 15.5%) than in control group (due in turn to a significantly greater amount of slow wave sleep (SWS, +14.6%). Similarly, frequency of SWS was greater in exposed group (by 4.9 episodes.h−1). The PS did not differ significantly between the two groups. During the dark period, there were no significant intergroup differences. We conclude that RF-EMF exposure induced a shift in thermal preference towards higher temperatures. The shift in preferred temperature might result from a cold thermal sensation. The change in sleep stage distribution may involve signals from thermoreceptors in the skin. Modulation of SWS may be a protective adaptation in response to RF-EMF exposure. PMID

  20. Effect of exposure to extremely low frequency magnetic fields on melatonin levels in calves is seasonally dependent

    PubMed Central

    Kolbabová, Tereza; Pascal Malkemper, E.; Bartoš, Luděk; Vanderstraeten, Jacques; Turčáni, Marek; Burda, Hynek

    2015-01-01

    The question of health effects of extremely low frequency (50/60 Hz) magnetic fields (ELFMF) has been widely discussed, but the mechanisms of interaction of these fields with biological systems for intensities relevant to human and animal exposure are still under question. The melatonin (MLT) hypothesis suggests that exposure to ELFMF might decrease MLT production thereby promoting cancerogenesis. So far, most studies of MLT secretion under exposure to ELFMF reported negative or inconsistent results. Here, we measured salivary MLT in 1–2 months old cattle calves exposed to 50 Hz-MF in the hundreds of nT-range. We found an inhibitory effect of the ELFMF upon MLT secretion in winter (in accordance with the MLT hypothesis). In contrast, in summer, MLT concentration was increased by ELFMF exposure (contrary to the MLT hypothesis). The inhibitory effect in winter was much stronger than the positive effect in summer. We hypothesize that this season-dependent effect upon MLT synthesis might by mediated by an effect of ELFMF upon the serotonin metabolism and conclude that future tests of ELFMF effects should also measure serotonin levels and consider association with the seasonal effects (photoperiod or temperature) during the exposure. PMID:26381579

  1. [Prevalence of insomnia in adults aged 18 to 60 years and exposure to electromagnetic fields in households of Barranquilla, Colombia].

    PubMed

    Peñuela-Epalza, Martha Elena; Páez-Jiménez, Daniela Alejandra; Castro-Cantillo, Laura Del Carmen; Harvey-Ortega, Joyce Carolina; Eljach-Cartagena, Javier Alexander; Banquett-Henao, Luis Alejandro

    2015-08-01

    Insomnia, a sleep disorder that affects both individual and public health, has not been studied in Barranquilla. Prior studies about the effects of exposure to electromagnetic fields on sleep disorders are controversial. To estimate the prevalence of insomnia symptoms in adults aged 18 to 60 years and its relation to the presence and intensity of electromagnetic fields in two neighborhoods of Barranquilla, Colombia. A cross-sectional study was carried out in 220 households located in two neighborhoods of Barranquilla, one with high exposure to radio and cell phone antennas and the other one with low exposure. After informed consent, a survey was applied among adults residing in 220 households to investigate the presence of insomnia symptoms, socio-demographic data and intake of medicines. When it was allowed, electromagnetic fields were measured with teslameters in bedrooms. The database was created in Excel™ and the data analysis was done with SPSS™, version 18. Insomnia, mainly of the mild type, was present in 74.5% of the total study population while 25.5% reported a normal sleep pattern. According to the sleeping test score we found a higher prevalence of insomnia in the neighborhood with greater exposure to radio antennas and cell towers (85.4%) than in the one with lower exposure (63.3%), prevalence ratio 1.34 (CI 95% 1.14-1.57). This study suggests a higher prevalence of insomnia among persons living in areas with higher exposure to electromagnetic fields where the number of radio antennas and cell towers was greater.

  2. DATA COLLECTED IN THE EPA'S NATIONAL EXPOSURE RESEARCH LABORATORY'S FIELD MEASUREMENT STUDIES TO EVALUATE AGGREGATE EXPOSURE

    EPA Science Inventory

    The Food Quality Protection Act of 1996 requires children's risk assessments to be conducted using high quality and high quantity data. Currently, data on children's exposures and exposure factors are limited and insufficient to address risk assessments that do not rely heavil...

  3. Computation of acoustic ressure fields produced in feline brain by high-intensity focused ultrasound

    NASA Astrophysics Data System (ADS)

    Omidi, Nazanin

    In 1975, Dunn et al. (JASA 58:512-514) showed that a simple relation describes the ultrasonic threshold for cavitation-induced changes in the mammalian brain. The thresholds for tissue damage were estimated for a variety of acoustic parameters in exposed feline brain. The goal of this study was to improve the estimates for acoustic pressures and intensities present in vivo during those experimental exposures by estimating them using nonlinear rather than linear theory. In our current project, the acoustic pressure waveforms produced in the brains of anesthetized felines were numerically simulated for a spherically focused, nominally f1-transducer (focal length = 13 cm) at increasing values of the source pressure at frequencies of 1, 3, and 9 MHz. The corresponding focal intensities were correlated with the experimental data of Dunn et al. The focal pressure waveforms were also computed at the location of the true maximum. For low source pressures, the computed waveforms were the same as those determined using linear theory, and the focal intensities matched experimentally determined values. For higher source pressures, the focal pressure waveforms became increasingly distorted, with the compressional amplitude of the wave becoming greater, and the rarefactional amplitude becoming lower than the values calculated using linear theory. The implications of these results for clinical exposures are discussed.

  4. Liquid crystal infiltrated photonic crystal fibers for electric field intensity measurements.

    PubMed

    Mathews, Sunish; Farrell, Gerald; Semenova, Yuliya

    2011-06-10

    The application of nematic liquid crystal infiltrated photonic crystal fiber as a sensor for electric field intensity measurement is demonstrated. The device is based on an intrinsic sensing mechanism for electric fields. The sensor probe, which consists of a 1  cm infiltrated section of photonic crystal fiber with a lateral size of ∼125  μm, is very compact with small size and weight. A simple all-fiber design for the sensor is employed in an intensity based measurement scheme. The transmitted and reflected power of the infiltrated photonic crystal fiber is shown to have a linear response with the applied electric field. The sensor is operated in the telecommunication window at 1550  nm. The temperature dependence of the device at this operating wavelength is also experimentally studied and discussed. These structures can be used to accurately measure electric field intensity and can be used for the fabrication of all-fiber sensors for high electric field environments as both an in-line and reflective type point sensor.

  5. Megagauss magnetic fields in ultra-intense laser generated dense plasmas

    NASA Astrophysics Data System (ADS)

    Shaikh, Moniruzzaman; Lad, Amit D.; Jana, Kamalesh; Sarkar, Deep; Dey, Indranuj; Kumar, G. Ravindra

    2017-01-01

    Table-top terawatt lasers can create relativistic light intensities and launch megaampere electron pulses in a solid. These pulses induce megagauss (MG) magnetic pulses, which in turn strongly affect the hot electron transport via electromagnetic instabilities. It is therefore crucial to characterize the MG magnetic fields in great detail. Here, we present measurements of the spatio-temporal evolution of MG magnetic fields produced by a high contrast (picosecond intensity contrast 10-9) laser in a dense plasma on a solid target. The MG magnetic field is measured using the magneto-optic Cotton-Mouton effect, with a time delayed second harmonic (400 nm) probe. The magnetic pulse created by the high contrast laser in a glass target peaks much faster and has a more rapid fall than that induced by a low contrast (10-6) laser.

  6. Intense-field molecular spectroscopy: Vibrational and rotational effects in harmonic generation by H+2

    NASA Astrophysics Data System (ADS)

    Aubanel, E. E.; Zuo, T.; Bandrauk, A. D.

    1994-05-01

    We present results of a complete treatment of electronic, vibrational, and rotational motion in numerical calculation of harmonic generation (HG) of 1064-nm laser radiation by the H+2 molecular ion for intensities 1013<=I<=1014 W/cm2. We show that efficient HG can be enhanced by suppression of photodissociation, a phenomenon which results from vibrational trapping in laser-field-induced potential wells. The HG spectra exhibit peaks clustered around even and odd harmonic orders. All peaks can be assigned to Raman-like transitions between dressed eigenstates of the field-molecule system. Rotational excitation is shown to compete with HG. Thus harmonic generation and photon scattering in molecules holds the promise of a potential diagnostic for molecular stabilization by intense laser fields.

  7. On the relationship between acoustic energy density flux near the jet and far field acoustic intensity

    NASA Technical Reports Server (NTRS)

    Maestrello, L.

    1973-01-01

    The relationship between the distribution of the outflow of acoustic energy over the jet boundary and the far-field directivity and intensity distribution is established by measurement and analysis. The numerical and experimental procedures involved have been checked out by using a known source. The results indicate that the acoustic power output per unit length of the jet, in the region from which the sound emanates, peaks at approximately 9 diameters downstream. The acoustic emission for a jet Strouhal number of about 0.3 exceeds the emission for all other Strouhal numbers nearly everywhere along the measurement plane. However, the far-field peak intensity distribution obtained from the contribution of each station was found to depend on the spatial extent of the region where sound emanates from the jet, which, in turn, depends more on the far-field angle than on the Strouhal number. The implications of these results for sound suppression techniques are discussed.

  8. Improving our knowledge of the rapid geomagnetic field intensity variation observed in Europe around 800 AD

    NASA Astrophysics Data System (ADS)

    Gómez-Paccard, M.; Chauvin, A.; Lanos, P.; Dufresne, P.; Kovacheva, M.; Hill, M. J.; Beamud, E.; Gutiérrez-Lloret, S.; Cañavate, V.; Blain, S.; Bouvier, A.; Oberlin, C.; Guibert, P.; Sapin, C.; Pringent, D.

    2011-12-01

    Available European data indicate that during the past 2500 years there have been periods of rapid intensity geomagnetic fluctuations interspersed with periods of little change. The challenge now is to precisely describe these rapid changes. The aim of this study is to obtain an improved description of the sharp geomagnetic intensity change that took place in Western Europe around 800 yrs AD as well as to investigate if this peak is observed at a continental scale. For this purpose 13 precisely dated early medieval Spanish pottery fragments, 4 archeological French kilns and a 3 collections of bricks used for the construction of different historical buildings from France and with ages ranging between 330 to 1290 AD have been studied. The material collected has been dated by archeological/historical constraints together with radiocarbon,thermoluminiscence (TL) and archeomagentic analysis. From classical Thellier experiments including TRM anisotropy and cooling rate corrections upon archeointensity estimates and conducted on 164 specimens (119 of them giving reliable results) ten new high-quality mean intensities have been obtained. The new intensity data together with a selection of the most reliable data from Western Europe have been relocated to the latitude of Paris and confirm the existence of an intensity maxima of ~85 μT centred at ~850 AD and related to intensity changes up to 20 μT per century. The results also indicate that a previous abrupt intensity change (reaching a maximum value of ~ 90 μT) took place in Western Europe around 650 AD. A selection of high-quality intensity data from Bulgaria, Italy and Greece indicate a very similar intensity trend for Eastern Europe. Although available data indicate that the duration of such periods of high intensities may be of less than one century more data are needed to infer the exact duration of these maximums. A comparison between the selected data and regional and global geomagnetic field models indicates that

  9. Public magnetic field exposure based on internal current density for electric low voltage systems.

    PubMed

    Keikko, Tommi; Seesvuori, Reino; Hyvönen, Martti; Valkealahti, Seppo

    2009-04-01

    A measurement concept utilizing a new magnetic field exposure metering system has been developed for indoor substations where voltage is transformed from a medium voltage of 10 or 20 kV to a low voltage of 400 V. The new metering system follows the guidelines published by the International Commission on Non-Ionizing Radiation Protection. It can be used to measure magnetic field values, total harmonic distortion of the magnetic field, magnetic field exposure ratios for public and workers, load current values, and total harmonic distortion of the load current. This paper demonstrates how exposure to non-sinusoidal magnetic fields and magnetic flux density exposure values can be compared directly with limit values for internal current densities in a human body. Further, we present how the magnetic field and magnetic field exposure behaves in the vicinity of magnetic field sources within the indoor substation and in the neighborhood. Measured magnetic fields around the substation components have been used to develop a measurement concept by which long-term measurements in the substations were performed. Long-term measurements revealed interesting and partly unexpected dependencies between the measured quantities, which have been further analyzed. The principle of this paper is to substitute a demanding exposure measurement with measurements of the basic quantities like the 50 Hz fundamental magnetic field component, which can be estimated based on the load currents for certain classes of substation lay-out.

  10. Cumulative radiation exposure from diagnostic imaging in intensive care unit patients

    PubMed Central

    Moloney, Fiachra; Fama, Daniel; Twomey, Maria; O’Leary, Ruth; Houlihane, Conor; Murphy, Kevin P; O’Neill, Siobhan B; O’Connor, Owen J; Breen, Dorothy; Maher, Michael M

    2016-01-01

    AIM: To quantify cumulative effective dose of intensive care unit (ICU) patients attributable to diagnostic imaging. METHODS: This was a prospective, interdisciplinary study conducted in the ICU of a large tertiary referral and level 1 trauma center. Demographic and clinical data including age, gender, date of ICU admission, primary reason for ICU admission, APACHE II score, length of stay, number of days intubated, date of death or discharge, and re-admission data was collected on all patients admitted over a 1-year period. The overall radiation exposure was quantified by the cumulative effective radiation dose (CED) in millisieverts (mSv) and calculated using reference effective doses published by the United Kingdom National Radiation Protection Board. Pediatric patients were selected for subgroup-analysis. RESULTS: A total of 2737 studies were performed in 421 patients. The total CED was 1704 mSv with a median CED of 1.5 mSv (IQR 0.04-6.6 mSv). Total CED in pediatric patients was 74.6 mSv with a median CED of 0.07 mSv (IQR 0.01-4.7 mSv). Chest radiography was the most commonly performed examination accounting for 83% of all studies but only 2.7% of total CED. Computed tomography (CT) accounted for 16% of all studies performed and contributed 97% of total CED. Trauma patients received a statistically significant higher dose [median CED 7.7 mSv (IQR 3.5-13.8 mSv)] than medical [median CED 1.4 mSv (IQR 0.05-5.4 mSv)] and surgical [median CED 1.6 mSv (IQR 0.04-7.5 mSv)] patients. Length of stay in ICU [OR = 1.12 (95%CI: 1.079-1.157)] was identified as an independent predictor of receiving a CED greater than 15 mSv. CONCLUSION: Trauma patients and patients with extended ICU admission times are at increased risk of higher CEDs. CED should be minimized where feasible, especially in young patients. PMID:27158429

  11. Neuroendocrine mediated effects of electromagnetic-field exposure: Possible role of the pineal gland

    SciTech Connect

    Wilson, W.B.; Stevens, R.G.; Anderson, L.E. )

    1989-01-01

    Reports from recent epidemiological studies have suggested a possible association between extremely low frequently (ELF; including 50- or 60-Hz) electric- and magnetic-field exposure, and increased risk of certain cancers, depression, and miscarriage. ELF field-induced pineal gland dysfunction is a possible etiological factor in these effects. Work in our laboratory and elsewhere has shown that ELF electromagnetic-field exposure can alter the normal circadian rhythm of melatonin synthesis and release in the pineal gland. Consequences of reduced or inappropriately timed melatonin release on the endocrine, neuronal, and immune systems are discussed. Laboratory data linking ELF field exposure to changes in pineal circadian rhythms in both animal and humans are reviewed. The authors suggest that the pineal gland, in addition to being a convenient locus for measuring dyschronogenic effects of ELF field exposure, may play a central role in biological response to these fields via alterations in the melatonin signal.

  12. Exposure to 2.45 GHz electromagnetic fields elicits an HSP-related stress response in rat hippocampus.

    PubMed

    Yang, Xue-Sen; He, Gen-Lin; Hao, Yu-Tong; Xiao, Yang; Chen, Chun-Hai; Zhang, Guang-Bin; Yu, Zheng-Ping

    2012-07-01

    The issue of possible neurobiological effects of the electromagnetic field (EMF) exposure is highly controversial. To determine whether electromagnetic field exposure could act as an environmental stimulus capable of producing stress responses, we employed the hippocampus, a sensitive target of electromagnetic radiation, to assess the changes in its stress-related gene and protein expression after EMF exposure. Adult male Sprague-Dawley rats with body restrained were exposed to a 2.45 GHz EMF at a specific absorption rate (SAR) of 6 W/kg or sham conditions. cDNA microarray was performed to examine the changes of gene expression involved in the biological effects of electromagnetic radiation. Of 2048 candidate genes, 23 upregulated and 18 downregulated genes were identified. Of these differential expression genes, two heat shock proteins (HSP), HSP27 and HSP70, are notable because expression levels of both proteins are increased in the rat hippocampus. Result from immunocytochemistry revealed that EMF caused intensive staining for HSP27 and HSP70 in the hippocampus, especially in the pyramidal neurons of cornu ammonis 3 (CA3) and granular cells of dentate gyrus (DG). The gene and protein expression profiles of HSP27 and HSP70 were further confirmed by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Our data provide direct evidence that exposure to electromagnetic fields elicits a stress response in the rat hippocampus.

  13. Development of a source-exposure matrix for occupational exposure assessment of electromagnetic fields in the INTEROCC study.

    PubMed

    Vila, Javier; Bowman, Joseph D; Figuerola, Jordi; Moriña, David; Kincl, Laurel; Richardson, Lesley; Cardis, Elisabeth

    2016-11-09

    To estimate occupational exposures to electromagnetic fields (EMF) for the INTEROCC study, a database of source-based measurements extracted from published and unpublished literature resources had been previously constructed. The aim of the current work was to summarize these measurements into a source-exposure matrix (SEM), accounting for their quality and relevance. A novel methodology for combining available measurements was developed, based on order statistics and log-normal distribution characteristics. Arithmetic and geometric means, and estimates of variability and maximum exposure were calculated by EMF source, frequency band and dosimetry type. The mean estimates were weighted by our confidence in the pooled measurements. The SEM contains confidence-weighted mean and maximum estimates for 312 EMF exposure sources (from 0 Hz to 300 GHz). Operator position geometric mean electric field levels for radiofrequency (RF) sources ranged between 0.8 V/m (plasma etcher) and 320 V/m (RF sealer), while magnetic fields ranged from 0.02 A/m (speed radar) to 0.6 A/m (microwave heating). For extremely low frequency sources, electric fields ranged between 0.2 V/m (electric forklift) and 11,700 V/m (high-voltage transmission line-hotsticks), whereas magnetic fields ranged between 0.14 μT (visual display terminals) and 17 μT (tungsten inert gas welding). The methodology developed allowed the construction of the first EMF-SEM and may be used to summarize similar exposure data for other physical or chemical agents.Journal of Exposure Science and Environmental Epidemiology advance online publication, 9 November 2016; doi:10.1038/jes.2016.60.

  14. Intensity-dependent two-electron emission dynamics with orthogonally polarized two-color laser fields

    NASA Astrophysics Data System (ADS)

    Yuan, Zongqiang; Ye, Difa; Xia, Qinzhi; Liu, Jie; Fu, Libin

    2015-06-01

    In this paper, we explore the intensity-dependent strong-field double ionization of Ne with orthogonally polarized two-color laser pulses consisting of 800- and 400-nm laser fields. The yield of Ne2+ as a function of the relative phase Δ ϕ of the two colors experiences a qualitative transition as the laser intensity decreases from the saturation regime to the far-below-saturation regime. In the saturation regime, our simulations well reproduce the recent experimental observations [Phys. Rev. Lett. 112, 193002 (2014), 10.1103/PhysRevLett.112.193002]. Turning to the far-below-saturation regime, however, we find that the observed small knee structure totally disappears and the maximum yield of Ne2+ is shifted by a π /2 phase. This is explained by the competition between the trajectory concentration effect and the Δ ϕ -dependent ionization rate of the tunneling electron. The possibility of controlling over the two-electron emission direction along the 400-nm field through the laser intensity is also investigated. We show that the two-electron emission direction can be reversed by changing the laser intensity for some vales of Δ ϕ , while this fails for some other values of Δ ϕ .

  15. Big brown bats (Eptesicus fuscus) maintain hearing sensitivity after exposure to intense band-limited noise.

    PubMed

    Simmons, Andrea Megela; Hom, Kelsey N; Simmons, James A

    2017-03-01

    Thresholds to short-duration narrowband frequency-modulated (FM) sweeps were measured in six big brown bats (Eptesicus fuscus) in a two-alternative forced choice passive listening task before and after exposure to band-limited noise (lower and upper frequencies between 10 and 50 kHz, 1 h, 116-119 dB sound pressure level root mean square; sound exposure level 152 dB). At recovery time points of 2 and 5 min post-exposure, thresholds varied from -4 to +4 dB from pre-exposure threshold estimates. Thresholds after sham (control) exposures varied from -6 to +2 dB from pre-exposure estimates. The small differences in thresholds after noise and sham exposures support the hypothesis that big brown bats do not experience significant temporary threshold shifts under these experimental conditions. These results confirm earlier findings showing stability of thresholds to broadband FM sweeps at longer recovery times after exposure to broadband noise. Big brown bats may have evolved a lessened susceptibility to noise-induced hearing losses, related to the special demands of echolocation.

  16. Anomalous photoelectron angular distribution in ionization of Kr in intense ultraviolet laser fields

    NASA Astrophysics Data System (ADS)

    Nakano, Motoyoshi; Otobe, Tomohito; Itakura, Ryuji

    2017-06-01

    We investigate multiphoton ionization of Kr for the formation of the two spin-orbit split states 1/2 2P and 3/2 2P of Kr+ in intense ultraviolet femtosecond laser fields (λ ≈ 398 nm, τ ≈ 50 fs). As the laser intensity increases from 8 to 39 TW cm-2, the photoelectron angular distribution (PAD) exhibits the anomalous enhancement in the direction perpendicular to the laser polarization. With the support of the time-dependent density functional theory taking account of the spin-orbit interaction, the measured anomalous PAD is ascribed to the autoionization to 3/2 2P.

  17. Intense Isolated Ultrashort Attosecond Pulse Generation in a Multi-Cycle Three-Colour Laser Field

    NASA Astrophysics Data System (ADS)

    Zhang, Gang-Tai

    2014-12-01

    An efficient method for generating an intense isolated ultrashort attosecond pulse is presented theoretically. By adding a 267 nm controlling pulse to a multi-cycle two-colour field, not only the spectral cutoff and the yields of the harmonic spectrum are evidently enhanced, but also the selection of the single quantum path is realised. Then a high-efficiency supercontinuum with a 504 eV bandwidth and smooth structure is obtained, which enables the production of an intense isolated 30 as pulse. In addition, the influences of the laser parameters on the supercontinuum and isolated attosecond pulse are investigated.

  18. Water intensity assessment of shale gas resources in the Wattenberg field in northeastern Colorado.

    PubMed

    Goodwin, Stephen; Carlson, Ken; Knox, Ken; Douglas, Caleb; Rein, Luke

    2014-05-20

    Efficient use of water, particularly in the western U.S., is an increasingly important aspect of many activities including agriculture, urban, and industry. As the population increases and agriculture and energy needs continue to rise, the pressure on water and other natural resources is expected to intensify. Recent advances in technology have stimulated growth in oil and gas development, as well as increasing the industry's need for water resources. This study provides an analysis of how efficiently water resources are used for unconventional shale development in Northeastern Colorado. The study is focused on the Wattenberg Field in the Denver-Julesberg Basin. The 2000 square mile field located in a semiarid climate with competing agriculture, municipal, and industrial water demands was one of the first fields where widespread use of hydraulic fracturing was implemented. The consumptive water intensity is measured using a ratio of the net water consumption and the net energy recovery and is used to measure how efficiently water is used for energy extraction. The water and energy use as well as energy recovery data were collected from 200 Noble Energy Inc. wells to estimate the consumptive water intensity. The consumptive water intensity of unconventional shale in the Wattenberg is compared with the consumptive water intensity for extraction of other fuels for other energy sources including coal, natural gas, oil, nuclear, and renewables. 1.4 to 7.5 million gallons is required to drill and hydraulically fracture horizontal wells before energy is extracted in the Wattenberg Field. However, when the large short-term total freshwater-water use is normalized to the amount of energy produced over the lifespan of a well, the consumptive water intensity is estimated to be between 1.8 and 2.7 gal/MMBtu and is similar to surface coal mining.

  19. Mapping the spatial patterns of field traffic and traffic intensity to predict soil compaction risks at the field scale

    NASA Astrophysics Data System (ADS)

    Duttmann, Rainer; Kuhwald, Michael; Nolde, Michael

    2015-04-01

    Soil compaction is one of the main threats to cropland soils in present days. In contrast to easily visible phenomena of soil degradation, soil compaction, however, is obscured by other signals such as reduced crop yield, delayed crop growth, and the ponding of water, which makes it difficult to recognize and locate areas impacted by soil compaction directly. Although it is known that trafficking intensity is a key factor for soil compaction, until today only modest work has been concerned with the mapping of the spatially distributed patterns of field traffic and with the visual representation of the loads and pressures applied by farm traffic within single fields. A promising method for for spatial detection and mapping of soil compaction risks of individual fields is to process dGPS data, collected from vehicle-mounted GPS receivers and to compare the soil stress induced by farm machinery to the load bearing capacity derived from given soil map data. The application of position-based machinery data enables the mapping of vehicle movements over time as well as the assessment of trafficking intensity. It also facilitates the calculation of the trafficked area and the modeling of the loads and pressures applied to soil by individual vehicles. This paper focuses on the modeling and mapping of the spatial patterns of traffic intensity in silage maize fields during harvest, considering the spatio-temporal changes in wheel load and ground contact pressure along the loading sections. In addition to scenarios calculated for varying mechanical soil strengths, an example for visualizing the three-dimensional stress propagation inside the soil will be given, using the Visualization Toolkit (VTK) to construct 2D or 3D maps supporting to decision making due to sustainable field traffic management.

  20. In vivo setup characterization for pulsed electromagnetic field exposure at 3 GHz

    NASA Astrophysics Data System (ADS)

    Collin, A.; Perrin, A.; Cretallaz, C.; Pla, S.; Arnaud-Cormos, D.; Debouzy, J. C.; Leveque, P.

    2016-08-01

    An in vivo setup for pulsed electric field exposure at 3 GHz is proposed and characterized in this work. The exposure system allows far field, whole-body exposure of six animals placed in Plexiglas cages with a circular antenna. Chronic exposures under 18 W incident average power (1-4 kW peak power) and acute exposures under 56 W incident average power (4.7 kW peak power) were considered. Numerical and experimental dosimetry of the setup allowed the accurate calculation of specific absorption rate (SAR) distributions under various exposure conditions. From rat model numerical simulations, the whole-body mean SAR values were 1.3 W kg-1 under chronic exposures and 4.1 W kg-1 under acute exposure. The brain-averaged SAR value was 1.8 W kg-1 and 5.7 W kg-1 under chronic and acute exposure, respectively. Under acute exposure conditions, a 10 g specific absorption of 1.8  ±  1.1 mJ · kg-1 value was obtained. With temperature rises below 0.8 °C, as measured or simulated on a gel phantom under typical in vivo exposures, this exposure system provides adequate conditions for in vivo experimental investigations under non-thermal conditions.

  1. Intense THz radiation produced in organic salt crystals for high-field applications

    NASA Astrophysics Data System (ADS)

    Vicario, C.; Ruchert, C.; Hauri, C. P.

    2013-03-01

    Organic stilbazolium salt crystals pumped by intense, ultrashort mid-infrared laser have been investigated for efficient THz generation by optical rectification. In this paper we present our latest results in view of the generation of single-cycle and high-field THz transient in the THz gap (0.1-10 THz). The organic rectifiers like DAST, OH1 and DSTMS combine extremely large optical susceptibility with excellent velocity matching between the infrared pump and the THz radiation. Our simple collinear conversion scheme provides THz beams with excellent focusing properties and single cycle electric field larger than 1.5 MV/cm and magnetic field strength beyond 0.5 Tesla. The source can potentially cover the full THz gap at field strength which is barely provided by other THz sources. The THz pulse is carrier-envelope phase stable and the polarity of the field can be easily inverted.

  2. Matching Intensity-Modulated Radiation Therapy to an Anterior Low Neck Field

    SciTech Connect

    Amdur, Robert J. Liu, Chihray; Li, Jonathan; Mendenhall, William; Hinerman, Russell

    2007-10-01

    When using intensity-modulated radiation therapy (IMRT) to treat head and neck cancer with the primary site above the level of the larynx, there are two basic options for the low neck lymphatics: to treat the entire neck with IMRT, or to match the IMRT plan to a conventional anterior 'low neck' field. In view of the potential advantages of using a conventional low neck field, it is important to look for ways to minimize or manage the problems of matching IMRT to a conventional radiotherapy field. Treating the low neck with a single anterior field and the standard larynx block decreases the dose to the larynx and often results in a superior IMRT plan at the primary site. The purpose of this article is to review the most applicable studies and to discuss our experience with implementing a technique that involves moving the position of the superior border of the low neck field several times during a single treatment fraction.

  3. Electric-field effects on the OH vibrational frequency and infrared absorption intensity for water

    NASA Astrophysics Data System (ADS)

    Hermansson, Kersti

    1993-07-01

    The variations of the anharmonic OH frequency and the infrared absorption intensity with field strength have been calculated for the uncoupled OH stretching vibration of a water molecule in a static, homogeneous electric field using ab initio methods at the MP4 level with a nearly saturated basis set. The OH frequency is found to be virtually independent of the field components perpendicular to the vibrating OH bond. For the parallel component, the frequency vs field curve is close to quadratic, with a maximum for a slightly negative (directed from H to O) field strength. The external field perturbation, defined as Vext(E∥,rOH)=Vtot(E∥, rOH)-Vfree(rOH), is found to be closely linear in rOH, except when the field strength E∥ is both large and negative. The linear external force constant is almost perfectly accounted for by the sum of two terms, -E∥ṡdμ∥free/drOH and -1/2ṡE∥ṡ∂μ∥induced/∂rOH. These derivatives are quite insensitive to the choice of basis-set. The ∂μ∥induced/∂rOH derivative is approximately proportional to E∥, and gives rise to the arclike shape of the frequency vs field curve. The frequency maximum occurs where ∂μ∥tot/∂rOH≊0. It is the sign of dμ∥free/drOH which determines that the frequency maximum occurs at a negative field strength for water (but at a positive field strength for OH-, for example), i.e., that a frequency red-shift (blue-shift for OH-) occurs when the molecule is bound. The linear relationship between the infrared absorption intensity and frequency of the water OH vibration is derived.

  4. Investigation of EEG changes during exposure to extremely low-frequency magnetic field to conduct brain signals.

    PubMed

    Shafiei, S A; Firoozabadi, S M; Tabatabaie, K Rasoulzadeh; Ghabaee, M

    2014-11-01

    There are evidences that confirm the effect of magnetic fields (MFs) on brain signals and some psychological disorders such as headache, migraine and depression. The aim of the present study was to investigate changes in EEG power spectrum due to localized exposure in different parts of the brain by extremely low-frequency magnetic fields (ELF-MFs) to extract some protocols for treatment of some psychological disorders. In addition, regular effects were investigated by increasing intensity of ELF-MF. Therefore, EEG relative power spectrum was evaluated at T4, T3, F3, F4, and Cz points, when all the points were exposed to MFs with 45, 17, 10, 5, and 3 Hz frequencies, separately. Intensity of MF was 0, 100, 240, or 360 μT in four sessions. Significant changes were observed in different EEG bands caused by locally exposing to ELF-MF in different points of brain (P < 0.05). Some exposure to MFs decreased alpha band of frontal and central areas in closed-eyes state. Based on the findings in this study, some protocols can be designed using a combination of various MFs exposures to conduct the brain signals that is necessary to evaluate clinically.

  5. The effects of prenatal exposure to a 900-MHz electromagnetic field on the 21-day-old male rat heart.

    PubMed

    Türedi, Sibel; Hancı, Hatice; Topal, Zehra; Ünal, Deniz; Mercantepe, Tolga; Bozkurt, İlyas; Kaya, Haydar; Odacı, Ersan

    2015-01-01

    The growing spread of mobile phone use is raising concerns about the effect on human health of the electromagnetic field (EMF) these devices emit. The purpose of this study was to investigate the effects on rat pup heart tissue of prenatal exposure to a 900 megahertz (MHz) EMF. For this purpose, pregnant rats were divided into experimental and control groups. Experimental group rats were exposed to a 900 MHz EMF (1 h/d) on days 13-21 of pregnancy. Measurements were performed with rats inside the exposure box in order to determine the distribution of EMF intensity. Our measurements showed that pregnant experimental group rats were exposed to a mean electrical field intensity of 13.77 V/m inside the box (0.50 W/m(2)). This study continued with male rat pups obtained from both groups. Pups were sacrificed on postnatal day 21, and the heart tissues were extracted. Malondialdehyde, superoxide dismutase and catalase values were significantly higher in the experimental group rats, while glutathione values were lower. Light microscopy revealed irregularities in heart muscle fibers and apoptotic changes in the experimental group. Electron microscopy revealed crista loss and swelling in the mitochondria, degeneration in myofibrils and structural impairments in Z bands. Our study results suggest that exposure to EMF in the prenatal period causes oxidative stress and histopathological changes in male rat pup heart tissue.

  6. Rigorous electromagnetic field simulation of two-beam interference exposures for the exploration of double patterning and double exposure scenarios

    NASA Astrophysics Data System (ADS)

    Erdmann, Andreas; Evanschitzky, Peter; Fühner, Tim; Schnattinger, Thomas; Xu, Cheng-Bai; Szmanda, Chuck

    2008-03-01

    The introduction of double patterning and double exposure technologies, especially in combination with hyper NA, increases the importance of wafer topography phenomena. Rigorous electromagnetic field (EMF) simulations of two beam interference exposures over non-planar wafers are used to explore the impact of the hardmask material and pattern on resulting linewidths and swing curves after the second lithography step. Moreover, the impact of the optical material contrast between the frozen and unfrozen resist in a pattern freezing process and the effect of a reversible contrast enhancement layer on the superposition of two subsequent lithographic exposures are simulated. The described simulation approaches can be used for the optimization of wafer stack configurations for double patterning and to identify appropriate optical material properties for alternative double patterning and double exposure techniques.

  7. Occupational exposure to electromagnetic fields and acute leukaemia: analysis of a case-control study

    PubMed Central

    Willett, E; McKinney, P; Fear, N; Cartwright, R; Roman, E

    2003-01-01

    Aims: To investigate whether the risk of acute leukaemia among adults is associated with occupational exposure to electromagnetic fields. Methods: Probable occupational exposure to electromagnetic fields at higher than typical residential levels was investigated among 764 patients diagnosed with acute leukaemia during 1991–96 and 1510 sex and age matched controls. A job exposure matrix was applied to the self reported employment histories to determine whether or not a subject was exposed to electromagnetic fields. Risks were assessed using conditional logistic regression for a matched analysis. Results: Study subjects considered probably ever exposed to electromagnetic fields at work were not at increased risk of acute leukaemia compared to those considered never exposed. Generally, no associations were observed on stratification by sex, leukaemia subtype, number of years since exposure stopped, or occupation; there was no evidence of a dose-response effect using increasing number of years exposed. However, relative to women considered never exposed, a significant excess of acute lymphoblastic leukaemia was observed among women probably exposed to electromagnetic fields at work that remained increased irrespective of time prior to diagnosis or job ever held. Conclusion: This large population based case-control study found little evidence to support an association between occupational exposure to electromagnetic fields and acute leukaemia. While an excess of acute lymphoblastic leukaemia among women was observed, it is unlikely that occupational exposure to electromagnetic fields was responsible, given that increased risks remained during periods when exposure above background levels was improbable. PMID:12883018

  8. Effect of dielectric spacer thickness on signal intensity of surface plasmon field-enhanced fluorescence spectroscopy.

    PubMed

    Murakami, Takashi; Arima, Yusuke; Toda, Mitsuaki; Takiguchi, Hiromi; Iwata, Hiroo

    2012-02-15

    Surface plasmon field-enhanced fluorescence spectroscopy (SPFS) combines enhanced field platform and fluorescence detection. Its advantages are the strong intensity of the electromagnetic field and the high signal/noise (S/N) ratio due to the localized evanescent field at the water/metal interface. However, the energy transfer from the fluorophore to the metal surface diminishes the fluorescence intensity, and this reduces the sensitivity. In this study, we tested whether polystyrene (PSt) could act as a dielectric layer to suppress the energy transfer from the fluorophore to the metal surface. We hypothesized that this would improve the sensitivity of SPFS-based immunoassays. We used α-fetoprotein (AFP) as a model tumor biomarker in the sandwich-type immunoassay. We determined the relationship between fluorescent signal intensity and PSt layer thickness and compared this to theoretical predictions. We found that the fluorescence signal increased by optimally controlling the thickness of the PSt layer. Our results indicated that the SPFS-based immunoassay is a promising clinical diagnostic tool for quantitatively determining the concentrations of low-level biomarkers in blood samples.

  9. Intensity and phase fields behind Phase Shifting Masks studied with High Resolution Interference Microscopy

    NASA Astrophysics Data System (ADS)

    Puthankovilakam, Krishnaparvathy; Scharf, Toralf; Herzig, Hans Peter; Weichelt, Tina; Zeitner, Uwe; Vogler, Uwe; Voelkel, Reinhard

    2015-03-01

    The proximity printing industry is in real need of high resolution results and it can be done using Phase Shift Mask (PSM) or by applying Optical Proximity Correction (OPC). In our research we are trying to find out details of how light fields behind the structures of photo masks develop in order to determine the best conditions and designs for proximity printing. We focus here on parameters that are used in real situation with gaps up to 50 μm and structure sizes down to 2 μm. The light field evolution behind the structures is studied and delivers insight in to precisions and tolerances that need to be respected. It is the first time that an experimental analysis of light propagation through mask is presented in detail, which includes information on intensity and phase. The instrument we use is known as High Resolution Interference Microscopy (HRIM). HRIM is a Mach-Zehnder interferometer which is capable of recording three dimensional distributions of intensity and phase with diffraction limited resolution. Our characterization technique allows plotting the evolution of the desired light field and therefore printable structure till the desired proximity gap. In this paper we discuss in detail the evolution of intensity and phase fields of elbow or corner structure at different position behind a phase mask and interpret the main parameters. Of particular interest are tolerances against proximity gap variation and the resolution in printed structures.

  10. High-intensity geomagnetic field 'spike' observed at ca. 3000 cal BP in Texas, USA

    NASA Astrophysics Data System (ADS)

    Bourne, Mark D.; Feinberg, Joshua M.; Stafford, Thomas W.; Waters, Michael R.; Lundelius, Ernest; Forman, Steven L.

    2016-05-01

    By observing the fluctuations in direction and intensity of the Earth's magnetic field through time, we increase our understanding of the fluid motions of the Earth's outer core that sustain the geomagnetic field, the geodynamo. Recent archaeomagnetic studies in the Near East have found extremely rapid increases - 'spikes' - in geomagnetic field intensity at ca. 3000 yr cal BP. These observations have proved problematic for our current understanding of core-flow. However, until now, these geomagnetic spikes had not been observed outside of the Near East, where they have been preserved in metallurgical slag and fired, mud brick walls. We present a new, fully oriented, geomagnetic secular variation and relative palaeointensity (RPI) record for the last 17,000 yr from Hall's Cave, Texas, whose complete, >3.8 m thick sedimentary sequence spans from the present to 16 , 850 ± 110 RC yr BP (Modern to 20,600 cal BP). Within the stable, cool climate of the cave, pedogenic and bioturbation processes are negligible to non-existent, thereby limiting post-depositional physical and geochemical alteration of the magnetic record. The sub-aerial and subterranean setting of the sedimentary sequence in Hall's Cave enabled us to collect oriented palaeomagnetic cubes from a previously excavated stratigraphic section. The palaeomagnetic samples yielded high-quality vectors. An age model for the sequence, determined using 15 AMS 14C-dates on individual bones from microvertebrates, was combined with the palaeomagnetic data to construct a secular variation record. The record is in broad agreement with predictions by Holocene field models for the site's location. However, starting ca. 3000 yr ago, the RPI data indicate an almost four-fold increase in geomagnetic field intensity lasting several hundred years. This record presents well-dated evidence, obtained using conventional techniques, for the existence of a geomagnetic intensity spike in North America that is contemporaneous with the

  11. FIRST SIMULTANEOUS DETECTION OF MOVING MAGNETIC FEATURES IN PHOTOSPHERIC INTENSITY AND MAGNETIC FIELD DATA

    SciTech Connect

    Lim, Eun-Kyung; Yurchyshyn, Vasyl; Goode, Philip

    2012-07-01

    The formation and the temporal evolution of a bipolar moving magnetic feature (MMF) was studied with high-spatial and temporal resolution. The photometric properties were observed with the New Solar Telescope at Big Bear Solar Observatory using a broadband TiO filter (705.7 nm), while the magnetic field was analyzed using the spectropolarimetric data obtained by Hinode. For the first time, we observed a bipolar MMF simultaneously in intensity images and magnetic field data, and studied the details of its structure. The vector magnetic field and the Doppler velocity of the MMF were also studied. A bipolar MMF with its positive polarity closer to the negative penumbra formed, accompanied by a bright, filamentary structure in the TiO data connecting the MMF and a dark penumbral filament. A fast downflow ({<=}2 km s{sup -1}) was detected at the positive polarity. The vector magnetic field obtained from the full Stokes inversion revealed that a bipolar MMF has a U-shaped magnetic field configuration. Our observations provide a clear intensity counterpart of the observed MMF in the photosphere, and strong evidence of the connection between the MMF and the penumbral filament as a serpentine field.

  12. Injury, intense dust exposure, and chronic disease among survivors of the World Trade Center terrorist attacks of September 11, 2001.

    PubMed

    Alper, Howard E; Yu, Shengchao; Stellman, Steven D; Brackbill, Robert M

    2017-12-01

    The World Trade Center attack of September 11, 2001 in New York City (9/11) exposed thousands of people to intense concentrations of hazardous materials that have resulted in reports of increased levels of asthma, heart disease, diabetes, and other chronic diseases along with psychological illnesses such as post-traumatic stress disorder (PTSD). Few studies have discriminated between health consequences of immediate (short-term or acute) intense exposures versus chronic residential or workplace exposures. We used proportional hazards methods to determine adjusted hazard ratios (AHRs) for associations between several components of acute exposures (e.g., injury, immersion in the dust cloud) and four chronic disease outcomes: asthma, other non-neoplastic lung diseases, cardiovascular disease, and diabetes, in 8701 persons free of those conditions prior to exposure and who were physically present during or immediately after the World Trade Center attacks. Participants were followed prospectively up to 11 years post-9/11. Heart disease exhibited a dose-response association with sustaining injury (1 injury type: AHR =2.0, 95% CI (Confidence Interval) 1.1-3.6; 2 injury types: AHR = 3.1, 95% CI 1.2-7.9; 3 or more injury types: AHR = 6.8, 95% CI 2.0-22.6), while asthma and other lung diseases were both significantly associated with dust cloud exposure (AHR = 1.3, 95% CI 1.0-1.6). Diabetes was not associated with any of the predictors assessed in this study. In this study we demonstrated that the acute exposures of injury and dust cloud that were sustained on 9/11/2001 had significant associations with later heart and respiratory diseases. Continued monitoring of 9/11 exposed persons' health by medical providers is warranted for the foreseeable future.

  13. Kidney-Sparing Methods for Extended-Field Intensity-Modulated Radiotherapy (EF-IMRT) in Cervical Carcinoma Treatment

    PubMed Central

    Kunogi, Hiroaki; Yamaguchi, Nanae; Terao, Yasuhisa; Sasai, Keisuke

    2016-01-01

    Coplanar extended-field intensity-modulated radiation therapy (EF-IMRT) targeting the whole-pelvic and para-aortic lymph nodes in patients with advanced cervical cancer results in impaired creatinine clearance. An improvement in renal function cannot be expected unless low-dose (approximately 10 Gy) kidney exposure is reduced. The dosimetric method should be considered during EF-IMRT planning to further reduce low-dose exposure to the kidneys. To assess the usefulness of non-coplanar EF-IMRT with kidney-avoiding beams to spare the kidneys during cervical carcinoma treatment in dosimetric analysis between non-coplanar and coplanar EF-IMRT, we compared the doses of the target organ and organs at risk, including the kidney, in 10 consecutive patients. To estimate the influence of EFRT on renal dysfunction, creatinine clearance values after treatment were also examined in 18 consecutive patients. Of these 18 patients, 10 patients who were included in the dosimetric analysis underwent extended field radiation therapy (EFRT) with concurrent chemotherapy, and eight patients underwent whole-pelvis radiation therapy with concurrent chemotherapy to treat cervical carcinoma between April 2012 and March 2015 at our institution. In the dosimetric analysis, non-coplanar EF-IMRT was effective at reducing low-dose (approximately 10 Gy) exposure to the kidneys, thus maintaining target coverage and sparing other organs at risk, such as the small bowel, rectum, and bladder, compared with coplanar EF-IMRT. Renal function in all 10 patients who underwent EFRT, including coplanar EF-IMRT (with kidney irradiation), was low after treatment, and differed significantly from that of the eight patients who underwent WPRT (no kidney irradiation) 6 months after the first day of treatment (P = 0.005). In conclusion, non-coplanar EF-IMRT should be considered in patients with advanced cervical cancer, particularly in patients with a long life expectancy or with pre-existing renal dysfunction. PMID

  14. Impact of high-intensity pulsed electric fields on carotenoids profile of tomato juice made of moderate-intensity pulsed electric field-treated tomatoes.

    PubMed

    Vallverdú-Queralt, Anna; Odriozola-Serrano, Isabel; Oms-Oliu, Gemma; Lamuela-Raventós, Rosa M; Elez-Martínez, Pedro; Martín-Belloso, Olga

    2013-12-01

    The effect of pulsed electric fields (PEF) on the carotenoid content of tomato juices was studied. First, moderate-intensity PEF (MIPEF) was applied to raw tomatoes. Afterwards, MIPEF-treated and untreated tomatoes were immediately refrigerated at 4 °C for 24 h and then, they were separately ground to produce tomato juices. Juices were treated by heat treatments or by high-intensity PEF (HIPEF) and stored under refrigeration for 56 days. MIPEF treatment of tomatoes increased the content of carotenoid compounds in tomato juices. An enhancement of 63-65% in 15-cis-lycopene was observed in juices prepared with MIPEF-treated tomatoes. A slight increase in cis-lycopene isomers was observed over time, whereas other carotenoids slightly decreased. However, HIPEF treated tomato juices maintained higher carotenoid content (10-20%) through the storage time than thermally and untreated juices. The combination of MIPEF and HIPEF treatments could be used not only to produce tomato juices with high carotenoid content but also, to maintain higher the carotenoid content during storage time.

  15. Numerical investigation of acoustic field in enclosures: Evaluation of active and reactive components of sound intensity

    NASA Astrophysics Data System (ADS)

    Meissner, Mirosław

    2015-03-01

    The paper focuses on a theoretical description and numerical evaluation of active and reactive components of sound intensity in enclosed spaces. As the study was dedicated to low-frequency room responses, a modal expansion of the sound pressure was used. Numerical simulations have shown that the presence of energy vortices whose size and distribution depend on the character of the room response is a distinctive feature of the active intensity field. When several modes with frequencies close to a source frequency are excited, the vortices within the room are positioned irregularly. However, if the response is determined by one or two dominant modes, a regular distribution of vortices in the room can be observed. The irrotational component of the active intensity was found using the Helmholtz decomposition theorem. As was evidenced by numerical simulations, the suppression of the vortical flow of sound energy in the nearfield permits obtaining a clear image of the sound source.

  16. Exposure of arctic field scientists to ultraviolet radiation evaluated using personal dosimeters.

    PubMed

    Cockell, C S; Scherer, K; Horneck, G; Rettberg, P; Facius, R; Gugg-Helminger, A; Driscoll, C; Lee, P

    2001-10-01

    During July 2000 we used an electronic personal dosimeter (X-2000) and a biological dosimeter (Deutsches Zentrum für Luft- und Raumfahrt: Biofilm) to characterize the UV radiation exposure of arctic field scientists involved in biological and geological fieldwork. These personnel were working at the Haughton impact structure on Devon Island (75 degrees N) in the Canadian High Arctic under a 24 h photoperiod. During a typical day of field activities under a clear sky, the total daily erythemally weighted exposure, as measured by electronic dosimetry, was up to 5.8 standard erythemal dose (SED). Overcast skies (typically 7-8 okta of stratus) reduced exposures by a mean of 54%. We estimate that during a month of field activity in July a typical field scientist at this latitude could potentially receive approximately 80 SED to the face. Because of body movements the upper body was exposed to a UV regimen that often changed on second-to-second time-scales as assessed by electronic dosimetry. Over a typical 10 min period on vehicle traverse, we found that erythemal exposure could vary to up to 87% of the mean exposure. Time-integrated exposures showed that the type of outdoor field activities in the treeless expanse of the polar desert had little effect on the exposure received. Although absolute exposure changed in accordance with the time of day, the exposure ratio (dose received over horizontal dose) did not vary much over the day. Under clear skies the mean exposure ratio was 0.35 +/- 0.12 for individual activities at different times of the day assessed using electronic dosimetry. Biological dosimetry showed that the occupation was important in determining daily exposures. In our study, scientists in the field received an approximately two-fold higher dose than individuals, such as medics and computer scientists, who spent the majority of their time in tents.

  17. The Human Exposure Model (HEM): A Tool to Support Rapid Assessment of Human Health Impacts from Near-Field Consumer Product Exposures

    EPA Science Inventory

    The US EPA is developing an open and publically available software program called the Human Exposure Model (HEM) to provide near-field exposure information for Life Cycle Impact Assessments (LCIAs). Historically, LCIAs have often omitted impacts from near-field sources of exposur...

  18. The Human Exposure Model (HEM): A Tool to Support Rapid Assessment of Human Health Impacts from Near-Field Consumer Product Exposures

    EPA Science Inventory

    The US EPA is developing an open and publically available software program called the Human Exposure Model (HEM) to provide near-field exposure information for Life Cycle Impact Assessments (LCIAs). Historically, LCIAs have often omitted impacts from near-field sources of exposur...

  19. Reproduction, growth, and development of rats during chronic exposure to multiple field strengths of 60-Hz electric fields

    SciTech Connect

    Rommereim, D.N.; Rommereim, R.L.; Sikov, M.R.; Buschbom, R.L.; Anderson, L.E. )

    1990-04-01

    A study with multiple exposure groups and large group sizes was performed to establish whether exposure to 60-Hz electric fields would result in reproductive and developmental toxicity. A response model was developed from previous results and tested in groups of rats exposed to electric fields at various field strengths. Female rats were mated, and sperm-positive animals randomly distributed among four groups: sham-exposed or exposed to 10, 65, or 130 kV/m, 60-Hz vertical electric fields. Animals were exposed for 19 hr/day throughout the experiment. During gestation, exposure to the higher field strengths resulted in slightly depressed weight gains of dams. Offspring were born in the field and remained with their dams through the suckling period. Numbers of pups per litter and pup mortality did not differ among the exposure groups. Dams exposed at 65 kV/m lost slightly more weight through the lactation period than the control group. Male pups exposed to higher field strengths gained slightly less weight from 4 to 21 days of age than did sham-exposed animals. At weaning, two F1 females per litter (randomly selected) continued on the same exposure regimen were mated at 11 weeks of age to unexposed males, and euthanized at 20 days of gestation. Uterine contents were evaluated, and all live fetuses were weighed and examined for external, visceral, and skeletal malformations. Fertility and gestational weight gain of F1 females were not affected by exposure, nor was prenatal viability or fetal body weight. No significant increase in the incidence of litters with malformations was observed. Although no developmental toxicity was detected, exposures produced physical changes in the dams, evidenced as a rust-colored deposit on the muzzle and ears (chromodacryorrhea) that increased in incidence and severity at 65 and 130 kV/m.

  20. Culturing of cells as influenced by exposure to AC and DC fields

    NASA Astrophysics Data System (ADS)

    Abdel-Salam, M.; Nakano, M.; Tanino, M.; Mizuno, A.

    2008-12-01

    This paper is aimed at investigating culturing of living cells as influenced by exposure to AC and DC ionized and non-ionized fields in a point-to-plane gap. A cell suspension including yeast was placed on the ground plane at the gap axis and exposed to AC and DC fields of varying magnitudes. The effect of exposure time, frequency of the AC fields and magnitude of the applied fields on the survival rate of cells was investigated. The survival rate was also investigated as influenced by blowing the ionized field by air.

  1. Holocene geomagnetic field intensity variations: Contribution from the low latitude Canary Islands site

    NASA Astrophysics Data System (ADS)

    Kissel, C.; Laj, C.; Rodriguez-Gonzalez, A.; Perez-Torrado, F.; Carracedo, J. C.; Wandres, C.

    2015-11-01

    New absolute paleomagnetic intensity (PI) are investigated from 37 lava flows located at Tenerife and Gran Canaria (Canary Islands). They complete previously published directional results from the same flows and therefore allow to examine the time variations of the full geomagnetic vector. Twenty-eight flows are radiocarbon dated between 1706 AD and about 13 200 BC and one is historical. Eight other flows are not dated but they have stratigraphic links with the dated flows and archeomagnetic ages had been attributed to them based on their paleomagnetic directions. Various mineralogical analyses were conducted, giving access to the nature of the magnetic minerals and to their grain size. We performed the original Thellier and Thellier paleointensity (PI) experiments with a success rate of about 65% coupling this experiment with the strict set of selection criteria PICRIT-03. The mean PIs at the flow level are based on 3 to 12 independent PI determinations except for one site in which only one reliable determination could be obtained. The data indicate some variability in the local field intensity with a prominent PI peak centered around 600 BC and reaching 80 μT (VADM 16 ×1022 Am2), documented for the first time in this region. Combined with the published data obtained from western Africa, Spain, Portugal, Morocco and the Azores within a 2000 km-radius around the Canary Islands, our data allow to construct a curve illustrating the Earth magnetic field intensity fluctuations for Southwestern Europe/Western Africa. This curve, compared to the one produced for the Middle East and one calculated for Central Asia shows that maximum intensity patches have a very large geographical extent. They do not yet appear clearly in the models of variations of the dipolar field intensity.

  2. Factors modifying the response of large animals to low-intensity radiation exposure

    NASA Technical Reports Server (NTRS)

    Page, N. P.; Still, E. T.

    1972-01-01

    In assessing the biological response to space radiation, two of the most important modifying factors are dose protraction and dose distribution to the body. Studies are reported in which sheep and swine were used to compare the hematology and lethality response resulting from radiation exposure encountered in a variety of forms, including acute (high dose-rate), chronic (low dose-rate), combinations of acute and chronic, and whether received as a continuous or as fractionated exposure. While sheep and swine are basically similar in response to acute radiation, their sensitivity to chronic irradiation is markedly different. Sheep remain relatively sensitive as the radiation exposure is protracted while swine are more resistant and capable of surviving extremely large doses of chronic irradiation. This response to chronic irradiation correlated well with changes in radiosensitivity and recovery following an acute, sublethal exposure.

  3. An algorithm for quantitatively estimating non-occupational pesticide exposure intensity for spouses in the Agricultural Health Study

    EPA Science Inventory

    Purpose: Women living or working on farms may be exposed to pesticides from direct occupational use of agricultural pesticides and from non-occupational pathways, such as take-home exposure from skin, clothes and shoes of farmworkers, drift from nearby fields, and pest treatments...

  4. Orbital Noise of the Earth Causes Intensity Fluctuation in the Geomagnetic Field

    NASA Technical Reports Server (NTRS)

    Liu, Han-Shou; Kolenkiewicz, R.; Wade, C., Jr.

    2003-01-01

    Orbital noise of Earth's obliquity can provide an insight into the core of the Earth that causes intensity fluctuations in the geomagnetic field. Here we show that noise spectrum of the obliquity frequency have revealed a series of frequency periods centered at 250-, 1OO-, 50-, 41-, 30-, and 26-kyr which are almost identical with the observed spectral peaks from the composite curve of 33 records of relative paleointensity spanning the past 800 kyr (Sint-800 data). A continuous record for the past two million years also reveals the presence of the major 100 kyr periodicity in obliquity noise and geomagnetic intensity fluctuations. These results of correlation suggest that obliquity noise may power the dynamo, located in the liquid outer core of the Earth, which generates the geomagnetic field.

  5. Scaling of Wave-Packet Dynamics in an Intense Midinfrared Field

    SciTech Connect

    Tate, J.; Agostini, P.; DiMauro, L. F.; Auguste, T.; Salieres, P.; Muller, H. G.

    2007-01-05

    A theoretical investigation is presented that examines the wavelength scaling from near-visible (0.8 {mu}m) to midinfrared (2 {mu}m) of the photoelectron distribution and high harmonics generated by a 'single' atom in an intense electromagnetic field. The calculations use a numerical solution of the time-dependent Schroedinger equation (TDSE) in argon and the strong-field approximation in helium. The scaling of electron energies ({lambda}{sup 2}), harmonic cutoff ({lambda}{sup 2}), and attochirp ({lambda}{sup -1}) agree with classical mechanics, but it is found that, surprisingly, the harmonic yield follows a {lambda}{sup -(5-6)} scaling at constant intensity. In addition, the TDSE results reveal an unexpected contribution from higher-order returns of the rescattering electron wave packet.

  6. Training in laparoscopic renal surgery, in a few weeks of intense exposure.

    PubMed

    Hennayake, S; Jayawardhena, D; Kumara, S; Sakelaris, G

    2005-08-01

    discharge for nephrectomy was 7 h, and for nephroureterectomy, heminephroureterectomy and bilateral nephrectomy 21, 23 and 43 h, respectively. Trainee A had been in pediatric surgery for 4 years and during a period of 6 weeks he assisted in five operations, but did not get the opportunity to perform independently. Trainee B had been in pediatric surgery for 13 years and during a period of 12 weeks he assisted in nine operations and performed three. Trainee C had been in pediatric surgery for 20 years and during a period of 6 weeks he assisted in five operations and performed one. Since returning to their overseas units, trainee B and trainee C have successfully performed two nephrectomies each. Retroperitoneoscopic renal surgery is within the grasp of any experienced urologist or urology trainee. With intensive exposure and one-to-one mentoring, 6-12 weeks would be sufficient to achieve adequate competence and confidence to perform a prone retroperitoneoscopic nephrectomy.

  7. Hexavalent chromium exposures and exposure-control technologies in American enterprise: results of a NIOSH field research study.

    PubMed

    Blade, L M; Yencken, M Story; Wallace, M E; Catalano, J D; Khan, A; Topmiller, J L; Shulman, S A; Martinez, A; Crouch, K G; Bennett, J S

    2007-08-01

    The National Institute for Occupational Safety and Health (NIOSH) conducted 21 field surveys in selected industries to characterize workers' exposures to hexavalent chromium-containing airborne particulate and to evaluate existing technologies for controlling these exposures. Hexavalent chromium Cr(VI) is a respiratory irritant and chronic inhalation may cause lung cancer. Primary evaluation methods included collection of full work shift, personal breathing-zone (PBZ) air samples for Cr(VI), measurement of ventilation system parameters, and documentation of processes and work practices. This study emphasized evaluation of engineering exposure control measures, so PBZ exposures were measured on the outside of personal protective equipment, for example, respirators. Field surveys were conducted in two chromium electroplating facilities, including one where full-shift PBZ exposures to Cr(VI) ranged from 3.0 to 16 times the 1 micro g/m(3)NIOSH recommended exposure limit (REL) despite several engineering controls on the plating tanks. At a painting and coating facility that used Cr(VI)-containing products, full-shift exposures of painters and helpers (2.4 to 55 micro g/m(3)) exceeded the REL, but LEV effectiveness was limited. Other operations evaluated included welding in construction; metal cutting operations on chromium-containing materials in ship breaking; chromate-paint removal with abrasive blasting; atomized alloy-spray coating; foundry operations; printing; and the manufacture of refractory brick, colored glass, prefabricated concrete products, and treated wood products. NIOSH researchers concluded that, in many of the evaluated processes, Cr(VI) exposures at or below the current NIOSH REL are achievable. However, for some processes, it is unclear whether controlling exposures to this range is consistently achievable without respirator use. Some operations involving the application of coatings and finishes may be among those most difficult to control to this

  8. Electronic and intraband optical properties of single quantum rings under intense laser field radiation

    SciTech Connect

    Radu, A.; Kirakosyan, A. A.; Baghramyan, H. M.; Barseghyan, M. G.; Laroze, D.

    2014-09-07

    The influence of an intense laser field on one-electron states and intraband optical absorption coefficients is investigated in two-dimensional GaAs/Ga{sub 0.7}Al{sub 0.3}As quantum rings. An analytical expression of the effective lateral confining potential induced by the laser field is obtained. The one-electron energy spectrum and wave functions are found using the effective mass approximation and exact diagonalization technique. We have shown that changes in the incident light polarization lead to blue- or redshifts in the intraband optical absorption spectrum. Moreover, we found that only blueshift is obtained with increasing outer radius of the quantum ring.

  9. Electron nuclear dynamics of LiH and HF in an intense laser field

    NASA Astrophysics Data System (ADS)

    Broeckhove, J.; Coutinho-Neto, M. D.; Deumens, E.; Öhrn, Y.

    1997-12-01

    The electron nuclear dynamics theory (END) extended to include a time-dependent external field is briefly described. The dynamical equations, in addition to the full electron nuclear coupling terms, now also contain the interactions of both the nuclei and the electrons with the external field. This extended END theory is applied to the study of vibrational excitations of the simple diatomics HF and LiH. The END results using an intense infrared laser field are compared with those of molecular dynamics as well as those from quantum wave-packet calculations. While the effect of the nonadiabatic electron-nuclear coupling terms on the vibrational dynamics is negligible for the chosen application, the electron-field coupling has a significant impact.

  10. Tunneling wave packets of atoms from intense elliptically polarized fields in natural geometry

    NASA Astrophysics Data System (ADS)

    Han, Meng; Li, Min; Liu, Ming-Ming; Liu, Yunquan

    2017-02-01

    We study strong-field tunneling of atoms in intense elliptically polarized laser fields in natural tunneling geometry. We obtain the temporal- and spatial-dependent tunneling ionization rates, the transverse and longitudinal momentum distributions, and the position distributions of the tunnel exit in parabolic coordinates. The tunneling electron wave packets at the tunnel exit are three dimensionally characterized for both momentum and spatial distributions. The conjunction between the tunneling point and the classical propagation of the widely used semiclassical model are naturally connected. We further calculate the ellipticity-dependent photoelectron momentum distributions on the detector, which are validated by comparison with the exact results through numerically solving the time-dependent Schrödinger equation. The theory clarifies crucial questions about strong-field tunneling ionization, which has important implications for the attoclock with elliptical or circular fields, photoelectron holography, molecular orbital imaging, etc.

  11. Magnetospheric Multiscale analysis of intense field-aligned Poynting flux near the Earth's plasma sheet boundary

    NASA Astrophysics Data System (ADS)

    Stawarz, J. E.; Eastwood, J. P.; Varsani, A.; Ergun, R. E.; Shay, M. A.; Nakamura, R.; Phan, T. D.; Burch, J. L.; Gershman, D. J.; Giles, B. L.; Goodrich, K. A.; Khotyaintsev, Y. V.; Lindqvist, P.-A.; Russell, C. T.; Strangeway, R. J.; Torbert, R. B.

    2017-07-01

    The Magnetospheric Multiscale mission is employed to examine intense Poynting flux directed along the background magnetic field toward Earth, which reaches amplitudes of nearly 2 mW/m2. The event is located within the plasma sheet but likely near the boundary at a geocentric distance of 9 RE in association with bulk flow signatures. The fluctuations have wavelengths perpendicular to the magnetic field of 124-264 km (compared to an ion gyroradius of 280 km), consistent with highly kinetic Alfvén waves. While the wave vector remains highly perpendicular to the magnetic field, there is substantial variation of the direction in the perpendicular plane. The field-aligned Poynting flux may be associated with kinetic Alfvén waves released along the separatrix by magnetotail reconnection and/or the radiation of waves excited by bursty bulk flow braking and may provide a means through which energy released by magnetic reconnection is transferred to the auroral region.

  12. Positron acceleration by sheath field in ultra-intense laser–solid interactions

    NASA Astrophysics Data System (ADS)

    Yan, Yonghong; Wu, Yuchi; Chen, Jia; Yu, Minghai; Dong, Kegong; Gu, Yuqiu

    2017-04-01

    A positron production experiment was performed by irradiating an ultra-intense picosecond laser on solid tantalum targets. Quasi-monoenergetic positron beams were obtained owing to the sheath field on the back of the target. The experiment shows that the peak energy of the positron spectrum has a linear relation with the reciprocal of the target diameter. A simple analytical model of the sheath field was constructed to explain the experimental data, which predicts the positron peak energy in terms of the target diameter and hot electron parameters. Based on the field model, Monte Carlo simulations were conducted to treat the positron production and acceleration self-consistently. The simulated spectra are in good agreement with most experiment results. The disagreement of the 1 mm diameter data reveals that the hot electron propagation along the target flank surface plays an important role in the sheath field set up. Several aspects involved in the positron acceleration are discussed.

  13. Coherent manipulation of absorption by intense fields in four level ladder system

    NASA Astrophysics Data System (ADS)

    Kumar, Pardeep; Dasgupta, Shubhrangshu

    2016-05-01

    Nonlinear optical processes attributed to the dependence of the susceptibility of the medium on the input fluence can be remarkably manipulated by the quantum interference and coherence. One of these processes, the optical bistability (OB), that refers to the possibilities of two stable outputs for the same input fields, can also be modified by quantum coherence. Further, the nonlinear dependence of the absorption on the power of the input light gives rise to interesting processes like saturable absorption (SA) and reverse saturable absorption (RSA). While the SA corresponds to the decrease in the absorption coefficient with the increase of intensity of input light, the RSA corresponds to otherwise, that finds applications in optical limiting. We show, using a four-level Ladder system, how a control field manipulates these processes for an intense probe field applied in the excited state transition. The nonlinear absorption increases whereas the threshold of OB decreases in presence of a control field. We further delineates how the control field and the decay rates modifies SA and RSA. The control of these processes find applications in optical switching, optical limiting and optical communications.

  14. The influence of intense electric fields on three-dimensional asymmetric magnetic reconnection

    SciTech Connect

    Pritchett, P. L.

    2013-06-15

    A three-dimensional particle-in-cell simulation of magnetic reconnection in an asymmetric configuration without a guide field and with temperature ratio T{sub i}/T{sub e}>1 demonstrates that intense perpendicular electric fields are produced on the low-density side of the current layer where there is a strong gradient in the plasma density. The simulation shows that the 3-D reconnection rate is unaffected by these intense electric fields, that the electron current layer near the X line remains coherent and does not break up, but that localized regions of strong energy dissipation exist along the low-density separatrices. Near the X line the dominant term in the generalized Ohm's law for the reconnection electric field remains the off-diagonal electron pressure gradient ∂P{sub exy}/∂x. On the low-beta separatrix, however, the anomalous drag −<δnδE{sub y}>/ makes an equally important contribution to that of the pressure gradient to the average E{sub y} field.

  15. Dalitz plot analysis of Coulomb exploding O{sub 3} in ultrashort intense laser fields

    SciTech Connect

    Matsuda, Akitaka; Takahashi, Eiji J.; Hishikawa, Akiyoshi

    2007-09-21

    The three-body Coulomb explosion of O{sub 3}, O{sub 3}{sup 3+}{yields}O{sup +}+O{sup +}+O{sup +}, in ultrashort intense laser fields (2x10{sup 15} W/cm{sup 2}) is studied with two different pulse durations (9 and 40 fs) by the coincidence momentum imaging method. In addition to a decrease in the total kinetic energy release, a broadening in the Dalitz plot distribution [Philos. Mag. 44, 1068 (1953)] is observed when the pulse duration is increased from 9 to 40 fs. The analysis based on a simple Coulomb explosion model shows that the geometrical structure of O{sub 3} remains almost unchanged during the interaction with the few-cycle intense laser fields, while a significant structural deformation along all the three vibrational coordinates, including the antisymmetric stretching coordinate, is identified in the 40 fs intense laser fields. The observed nuclear dynamics are discussed in terms of the population transfer to the excited states of O{sub 3}.

  16. Acoustic characterization of high intensity focused ultrasound fields: A combined measurement and modeling approach

    PubMed Central

    Canney, Michael S.; Bailey, Michael R.; Crum, Lawrence A.; Khokhlova, Vera A.; Sapozhnikov, Oleg A.

    2008-01-01

    Acoustic characterization of high intensity focused ultrasound (HIFU) fields is important both for the accurate prediction of ultrasound induced bioeffects in tissues and for the development of regulatory standards for clinical HIFU devices. In this paper, a method to determine HIFU field parameters at and around the focus is proposed. Nonlinear pressure waveforms were measured and modeled in water and in a tissue-mimicking gel phantom for a 2 MHz transducer with an aperture and focal length of 4.4 cm. Measurements were performed with a fiber optic probe hydrophone at intensity levels up to 24 000 W∕cm2. The inputs to a Khokhlov–Zabolotskaya–Kuznetsov-type numerical model were determined based on experimental low amplitude beam plots. Strongly asymmetric waveforms with peak positive pressures up to 80 MPa and peak negative pressures up to 15 MPa were obtained both numerically and experimentally. Numerical simulations and experimental measurements agreed well; however, when steep shocks were present in the waveform at focal intensity levels higher than 6000 W∕cm2, lower values of the peak positive pressure were observed in the measured waveforms. This underrepresentation was attributed mainly to the limited hydrophone bandwidth of 100 MHz. It is shown that a combination of measurements and modeling is necessary to enable accurate characterization of HIFU fields. PMID:19062878

  17. Acoustic characterization of high intensity focused ultrasound fields: a combined measurement and modeling approach.

    PubMed

    Canney, Michael S; Bailey, Michael R; Crum, Lawrence A; Khokhlova, Vera A; Sapozhnikov, Oleg A

    2008-10-01

    Acoustic characterization of high intensity focused ultrasound (HIFU) fields is important both for the accurate prediction of ultrasound induced bioeffects in tissues and for the development of regulatory standards for clinical HIFU devices. In this paper, a method to determine HIFU field parameters at and around the focus is proposed. Nonlinear pressure waveforms were measured and modeled in water and in a tissue-mimicking gel phantom for a 2 MHz transducer with an aperture and focal length of 4.4 cm. Measurements were performed with a fiber optic probe hydrophone at intensity levels up to 24,000 W/cm(2). The inputs to a Khokhlov-Zabolotskaya-Kuznetsov-type numerical model were determined based on experimental low amplitude beam plots. Strongly asymmetric waveforms with peak positive pressures up to 80 MPa and peak negative pressures up to 15 MPa were obtained both numerically and experimentally. Numerical simulations and experimental measurements agreed well; however, when steep shocks were present in the waveform at focal intensity levels higher than 6000 W/cm(2), lower values of the peak positive pressure were observed in the measured waveforms. This underrepresentation was attributed mainly to the limited hydrophone bandwidth of 100 MHz. It is shown that a combination of measurements and modeling is necessary to enable accurate characterization of HIFU fields.

  18. The role of the magnetic field intensity and geometry in the type III burst generation

    NASA Astrophysics Data System (ADS)

    Zlobec, P.; Messerotti, M.; Ruzdjak, V.; Vrsnak, B.; Karlicky, M.

    1990-12-01

    The association of type III bursts related to H-alpha flares in different magnetic environments were studied in the period 1970-1981. Special attention is paid to flares which partly cover a major spot umbra (Z-flares). In particular, the location of the spots in the active regions and the magnetic field intensities of spots covered by a ribbon are considered. The association rate with type III bursts decreases to 17 percent when the flare is located inside the bipolar pattern of a large active region, compared with an association rate of 54 percent when the flare is situated outside it. The association rate increases with the magnetic field intensity of the spot covered by H-alpha emission; this is most clearly revealed for the flares occurring outside the bipolar pattern of active regions. Ninety-three percent of the flare-associated type III burst were accompanied by 10 cm radio bursts. For the most general case, in which a flare is developing anywhere in an active region, the association with type III bursts generation increases with the increasing magnetic field intensity of the main spot of the group.

  19. Intensity and phase fields behind phase-shifting masks studied with high-resolution interference microscopy

    NASA Astrophysics Data System (ADS)

    Puthankovilakam, Krishnaparvathy; Scharf, Toralf; Kim, Myun Sik; Naqavi, Ali; Herzig, Hans Peter; Weichelt, Tina; Zeitner, Uwe; Vogler, Uwe; Voelkel, Reinhard

    2016-04-01

    We try to find out the details of how light fields behind the structures of photomasks develop in order to determine the best conditions and designs for proximity printing. The parameters that we use approach real situations like structure printing at proximity gaps of 20 to 50 μm and structure sizes down to 2 μm. This is the first time that an experimental analysis of light propagation through a mask is presented in detail, which includes information on intensity and phase. We use high-resolution interference microscopy (HRIM) for the measurement. HRIM is a Mach-Zehnder interferometer, which is capable of recording three-dimensional distributions of intensity and phase with diffraction-limited resolution. Our characterization technique allows plotting the evolution of the desired light field, usually called the aerial image, and therefore gives access to the printable structure until the desired proximity gap. Here, we discuss in detail the evolution of intensity and phase fields of elbow or corner structures at different positions behind a phase mask and interpret the main parameters. Of particular interest are tolerances against proximity gap variation and the theoretical explanation of the resolution in printed structures.

  20. Monitoring tropical cyclone intensity using wind fields derived from short-interval satellite images

    NASA Technical Reports Server (NTRS)

    Rodgers, E. B.; Gentry, R. C.

    1981-01-01

    Rapid scan visible images from the Visible Infrared Spin Scan Radiometer sensor on board SMS-2 and GOES-1 were used to derive high resolution upper and lower tropospheric environmental wind fields around three western Atlantic tropical cyclones (1975-78). These wind fields were used to derive upper and lower tropospheric areal mean relative vorticity and their differences, the net relative angular momentum balance and upper tropospheric mass outflow. These kinematic parameters were shown by studies using composite rawinsonde data to be strongly related to tropical cyclone formation and intensity changes. Also, the role of forced synoptic scale subsidence in tropical cyclone formation was examined. The studies showed that satellite-derived lower and upper tropospheric wind fields can be used to monitor and possibly predict tropical cyclone formation and intensity changes. These kinematic analyses showed that future changes in tropical cyclone intensity are mainly related to the "spin-up" of the storms by the net horizontal transport of relative angular momentum caused by convergence of cyclonic vorticity in the lower troposphere and to a lesser extent the divergence of anticyclone vorticity in the upper troposphere.

  1. MAGNETIC FLUX CONSERVATION IN THE HELIOSHEATH INCLUDING SOLAR CYCLE VARIATIONS OF MAGNETIC FIELD INTENSITY

    SciTech Connect

    Michael, A. T.; Opher, M.; Provornikova, E.; Richardson, J. D.; Tóth, G. E-mail: mopher@bu.edu E-mail: jdr@space.mit.edu

    2015-04-10

    In the heliosheath (HS), Voyager 2 has observed a flow with constant radial velocity and magnetic flux conservation. Voyager 1, however, has observed a decrease in the flow’s radial velocity and an order of magnitude decrease in magnetic flux. We investigate the role of the 11 yr solar cycle variation of the magnetic field strength on the magnetic flux within the HS using a global 3D magnetohydrodynamic model of the heliosphere. We use time and latitude-dependent solar wind velocity and density inferred from Solar and Heliospheric Observatory/SWAN and interplanetary scintillations data and implemented solar cycle variations of the magnetic field derived from 27 day averages of the field magnitude average of the magnetic field at 1 AU from the OMNI database. With the inclusion of the solar cycle time-dependent magnetic field intensity, the model matches the observed intensity of the magnetic field in the HS along both Voyager 1 and 2. This is a significant improvement from the same model without magnetic field solar cycle variations, which was over a factor of two larger. The model accurately predicts the radial velocity observed by Voyager 2; however, the model predicts a flow speed ∼100 km s{sup −1} larger than that derived from LECP measurements at Voyager 1. In the model, magnetic flux is conserved along both Voyager trajectories, contrary to observations. This implies that the solar cycle variations in solar wind magnetic field observed at 1 AU does not cause the order of magnitude decrease in magnetic flux observed in the Voyager 1 data.

  2. Intraoperative observation of changes in cochlear nerve action potentials during exposure to electromagnetic fields generated by mobile phones.

    PubMed

    Colletti, Vittorio; Mandalà, Marco; Manganotti, Paolo; Ramat, Stefano; Sacchetto, Luca; Colletti, Liliana

    2011-07-01

    The rapid spread of devices generating electromagnetic fields (EMF) has raised concerns as to the possible effects of this technology on humans. The auditory system is the neural organ most frequently and directly exposed to electromagnetic activity owing to the daily use of mobile phones. In recent publications, a possible correlation between mobile phone usage and central nervous system tumours has been detected. Very recently a deterioration in otoacoustic emissions and in the auditory middle latency responses after intensive and long-term magnetic field exposure in humans has been demonstrated. To determine with objective observations if exposure to mobile phone EMF affects acoustically evoked cochlear nerve compound action potentials, seven patients suffering from Ménière's disease and undergoing retrosigmoid vestibular neurectomy were exposed to the effects of mobile phone placed over the craniotomy for 5 min. All patients showed a substantial decrease in amplitude and a significant increase in latency of cochlear nerve compound action potentials during the 5 min of exposure to EMF. These changes lasted for a period of around 5 min after exposure. The possibility that EMF can produce relatively long-lasting effects on cochlear nerve conduction is discussed and analysed in light of contrasting previous literature obtained under non-surgical conditions. Limitations of this novel approach, including the effects of the anaesthetics, craniotomy and surgical procedure, are presented in detail.

  3. The Revised Electromagnetic Fields Directive and Worker Exposure in Environments With High Magnetic Flux Densities

    PubMed Central

    Stam, Rianne

    2014-01-01

    Some of the strongest electromagnetic fields (EMF) are found in the workplace. A European Directive sets limits to workers’ exposure to EMF. This review summarizes its origin and contents and compares magnetic field exposure levels in high-risk workplaces with the limits set in the revised Directive. Pubmed, Scopus, grey literature databases, and websites of organizations involved in occupational exposure measurements were searched. The focus was on EMF with frequencies up to 10 MHz, which can cause stimulation of the nervous system. Selected studies had to provide individual maximum exposure levels at the workplace, either in terms of the external magnetic field strength or flux density or as induced electric field strength or current density. Indicative action levels and the corresponding exposure limit values for magnetic fields in the revised European Directive will be higher than those in the previous version. Nevertheless, magnetic flux densities in excess of the action levels for peripheral nerve stimulation are reported for workers involved in welding, induction heating, transcranial magnetic stimulation, and magnetic resonance imaging (MRI). The corresponding health effects exposure limit values for the electric fields in the worker’s body can be exceeded for welding and MRI, but calculations for induction heating and transcranial magnetic stimulation are lacking. Since the revised European Directive conditionally exempts MRI-related activities from the exposure limits, measures to reduce exposure may be necessary for welding, induction heating, and transcranial nerve stimulation. Since such measures can be complicated, there is a clear need for exposure databases for different workplace scenarios with significant EMF exposure and guidance on good practices. PMID:24557933

  4. The revised electromagnetic fields directive and worker exposure in environments with high magnetic flux densities.

    PubMed

    Stam, Rianne

    2014-06-01

    Some of the strongest electromagnetic fields (EMF) are found in the workplace. A European Directive sets limits to workers' exposure to EMF. This review summarizes its origin and contents and compares magnetic field exposure levels in high-risk workplaces with the limits set in the revised Directive. Pubmed, Scopus, grey literature databases, and websites of organizations involved in occupational exposure measurements were searched. The focus was on EMF with frequencies up to 10 MHz, which can cause stimulation of the nervous system. Selected studies had to provide individual maximum exposure levels at the workplace, either in terms of the external magnetic field strength or flux density or as induced electric field strength or current density. Indicative action levels and the corresponding exposure limit values for magnetic fields in the revised European Directive will be higher than those in the previous version. Nevertheless, magnetic flux densities in excess of the action levels for peripheral nerve stimulation are reported for workers involved in welding, induction heating, transcranial magnetic stimulation, and magnetic resonance imaging (MRI). The corresponding health effects exposure limit values for the electric fields in the worker's body can be exceeded for welding and MRI, but calculations for induction heating and transcranial magnetic stimulation are lacking. Since the revised European Directive conditionally exempts MRI-related activities from the exposure limits, measures to reduce exposure may be necessary for welding, induction heating, and transcranial nerve stimulation. Since such measures can be complicated, there is a clear need for exposure databases for different workplace scenarios with significant EMF exposure and guidance on good practices.

  5. Comparison of personal radio frequency electromagnetic field exposure in different urban areas across Europe

    SciTech Connect

    Joseph, Wout; Thuroczy, Gyoergy; Gajsek, Peter; Trcek, Tomaz; Bolte, John; Vermeeren, Guenter; Juhasz, Peter; Finta, Viktoria

    2010-10-15

    Background: Only limited data are available on personal radio frequency electromagnetic field (RF-EMF) exposure in everyday life. Several European countries performed measurement studies in this area of research. However, a comparison between countries regarding typical exposure levels is lacking. Objectives: To compare for the first time mean exposure levels and contributions of different sources in specific environments between different European countries. Methods: In five countries (Belgium, Switzerland, Slovenia, Hungary, and the Netherlands), measurement studies were performed using the same personal exposure meters. The pooled data were analyzed using the robust regression on order statistics (ROS) method in order to allow for data below the detection limit. Mean exposure levels were compared between different microenvironments such as homes, public transports, or outdoor. Results: Exposure levels were of the same order of magnitude in all countries and well below the international exposure limits. In all countries except for the Netherlands, the highest total exposure was measured in transport vehicles (trains, car, and busses), mainly due to radiation from mobile phone handsets (up to 97%). Exposure levels were in general lower in private houses or flats than in offices and outdoors. At home, contributions from various sources were quite different between countries. Conclusions: Highest total personal RF-EMF exposure was measured inside transport vehicles and was well below international exposure limits. This is mainly due to mobile phone handsets. Mobile telecommunication can be considered to be the main contribution to total RF-EMF exposure in all microenvironments.

  6. Exposure of children to extremely low frequency magnetic fields in France: Results of the EXPERS study.

    PubMed

    Magne, Isabelle; Souques, Martine; Bureau, Isabelle; Duburcq, Anne; Remy, Emmanuel; Lambrozo, Jacques

    2017-09-01

    The assessment of magnetic field exposure in children is an important point in the context of epidemiological issues. EXPERS is the first study ever carried out measuring personal exposure to extremely low frequency magnetic fields at a national scale, involving 977 French children with 24 h personal measurements. Descriptive statistical analyses were performed for all the children, and only for children where no alarm clock was identified, as in some cases this requirement of the measurement protocol was not respected. The proportion of children with a 24 h arithmetic mean of ≥0.4 μT was 3.1% when considering all children and 0.8% when excluding alarm clocks. The alarm clocks were the main variable linked to the child exposure measurements. Magnetic field exposure increased when the home was located close to a high voltage power line. However, none of the 0.8% of children living at <125 m to a 225 kV line or <200 m to a 400 kV overhead line had a personal exposure of >0.4 μT. A multiple correspondence analysis showed the difficulty to build a statistical model predicting child exposure. The distribution of child personal exposure was significantly different from the distribution of exposure during sleep, questioning the exposure assessment in some epidemiological studies.

  7. A localized ELF magnetic field exposure system for microscope cover-slips.

    PubMed

    Wang, Paul K C

    2014-07-01

    In extremely low frequency (ELF) magnetic field exposure systems for the inverted microscope stage where the cells grown on the entire microscope cover-slip are exposed to the magnetic field, the effects of variations in cell characteristics from one cover-slip to another on the experimental data cannot be readily identified. To overcome this drawback, a localized ELF magnetic field exposure system for cells grown on cover-slips was designed. The basic idea is to expose only a marked portion of the cover-slip to the magnetic field so that the effect of the ELF magnetic field on the cells grown on the same cover-slip can be observed under a microscope. A prototype system was built and tested. Experimental test results pertaining to the prototype system performance validate the proposed design approach. The paper concludes with a discussion of alternative approaches to the design of localized ELF magnetic field exposure systems.

  8. Local exposure of brain central areas to a pulsed ELF magnetic field for a purposeful change in EEG.

    PubMed

    Amirifalah, Zeinab; Firoozabadi, S Mohammad P; Shafiei, S Ali

    2013-01-01

    This study examines the simultaneous exposure of 2 brain areas in the location of central electrodes (C3 and C4) to a weak and pulsed extremely low-frequency magnetic field (ELF-MF) on the electroencephalogram (EEG). The intent is to change the EEG for a therapeutic application, such as neurofeedback, by inducing the "resonance effect." A total of 10 healthy women received 9 minutes of ELF-MF (intensity 200 μT) and sham in a counterbalanced design. ELF-MF exposure frequencies were 10, 14, and 18 Hz. The paired t test revealed that local pulsed ELF-MF significantly decreases beta (15-25 Hz), sensorimotor rhythm (13-15 Hz), and theta (4-8 Hz) powers at a frequency of 10 Hz in C3 and C4 regions (12.0%-26.6%) after exposure, in comparison with that achieved during the exposure (P < .05). Variations during the exposure were transient and different from those after. The resonance effect was observed nowhere around the regions. The study suggests that this technique may be applied in the treatment of anxiety; however, further investigation is needed.

  9. Incidence of Sepsis and Mortality With Prior Exposure of HMG-COA Reductase Inhibitors in a Surgical Intensive Care Population.

    PubMed

    Schurr, James W; Wu, Wenchen; Smith-Hannah, Alexandria; Smith, Candace J; Barrera, Rafael

    2016-01-01

    The anti-inflammatory properties of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) may reduce the risk of developing sepsis in surgical intensive care patients and improve outcomes in those who do become septic. The objective of this study was to assess whether surgical intensive care unit (SICU) patients with prior exposure to HMG-CoA reductase inhibitors had a lower incidence of developing sepsis and improved outcomes. A retrospective cohort study was conducted. Patient demographic data, statin use, sequential organ failure assessment (SOFA) scores, vasopressor requirements, ventilator days, length of SICU stay, and mortality in septic patients were collected. Incidence of development of sepsis was determined using systemic inflammatory response syndrome criteria. Patients were grouped into cohorts based on whether they met the sepsis criteria and if they had previously received statins. Cohorts of patients who did and did not become septic with prior statin exposure were compared and an odds ratio was calculated to determine a protective effect. The setting was a SICU. The study comprised of 455 SICU patients and had no interventions. Among the 455 SICU patients, 427 patients were included for the final results. Patients receiving statins verses not receiving statins were similar in demographics. Previous statin exposure had a protective effect in the development of sepsis (9.77% on statins vs. 33.6% without statins; odds ratio 0.203, confidence interval 0.118-0.351). Of those patients who developed sepsis, there was a statistically significant decrease in 28-day mortality in patients with prior statin exposure (P = 0.0341). No statistical difference was noted in length of stay, vasopressor requirements, or days on mechanical ventilation. Prior exposure to statins may have a protective effect on the development of sepsis and decrease mortality in critically ill surgical patients.

  10. Effect of electric field exposure on melatonin and enzyme circadian rhythms in the rat pineal

    SciTech Connect

    Wilson, B.; Anderson, L.E.; Hilton, D.I.; Phillips, R.D.

    1980-11-01

    The effects of chronic 30-day electric field exposure on pineal serotonin N-acetyl transferase (EC 2.1.15) activity as well as melatonin and 5-methoxy tryptophol (5-MTOL) concentrations in rats, were assessed.

  11. Agreement between two methods for retrospective assessment of occupational exposure intensity to six chlorinated solvents: Data from The National Birth Defects Prevention Study.

    PubMed

    Johnson, Candice Y; Rocheleau, Carissa M; Hein, Misty J; Waters, Martha A; Stewart, Patricia A; Lawson, Christina C; Reefhuis, Jennita

    2017-05-01

    The wide variety of jobs encountered in population-based studies makes retrospective exposure assessment challenging in occupational epidemiology. In this analysis, two methods for estimating exposure intensity to chlorinated solvents are compared: rated (assigned by an expert rater) and modeled (assigned using statistical models). Estimates of rated and modeled intensities were compared for jobs held by mothers participating in the National Birth Defects Prevention Study with possible exposure to six chlorinated solvents: carbon tetrachloride, chloroform, methylene chloride, perchloroethylene, 1,1,1-trichloroethane, and trichloroethylene. For each possibly exposed job, an industrial hygienist assigned (1) an exposure intensity (rated intensity) and (2) determinants of exposure to be used in a statistical model of exposure intensity (modeled intensity). Of 12,326 reported jobs, between 31 (0.3%) and 746 (6%) jobs were rated as possibly exposed to each of the six solvents. Agreement between rated and modeled intensities was low overall (Spearman correlation coefficient range: -0.09 to 0.28; kappa range: -0.23 to 0.43). Although no air measurements were available to determine if rated or modeled estimates were more accurate, review of participants' job titles showed that modeled estimates were often unexpectedly high given the low-exposure tasks found in these jobs. Differences between the high-exposure jobs used to create the statistical models (obtained from air measurements in the published literature) and the low-exposure jobs in the actual study population is a potential explanation for the disagreement between the two methods. Investigators should be aware that statistical models estimating exposure intensity using existing data from one type of worker population might not be generalizable to all populations of workers.

  12. Statistical analysis of geomagnetic field intensity differences between ASM and VFM instruments onboard Swarm constellation

    NASA Astrophysics Data System (ADS)

    De Michelis, Paola; Tozzi, Roberta; Consolini, Giuseppe

    2017-02-01

    From the very first measurements made by the magnetometers onboard Swarm satellites launched by European Space Agency (ESA) in late 2013, it emerged a discrepancy between scalar and vector measurements. An accurate analysis of this phenomenon brought to build an empirical model of the disturbance, highly correlated with the Sun incidence angle, and to correct vector data accordingly. The empirical model adopted by ESA results in a significant decrease in the amplitude of the disturbance affecting VFM measurements so greatly improving the vector magnetic data quality. This study is focused on the characterization of the difference between magnetic field intensity measured by the absolute scalar magnetometer (ASM) and that reconstructed using the vector field magnetometer (VFM) installed on Swarm constellation. Applying empirical mode decomposition method, we find the intrinsic mode functions (IMFs) associated with ASM-VFM total intensity differences obtained with data both uncorrected and corrected for the disturbance correlated with the Sun incidence angle. Surprisingly, no differences are found in the nature of the IMFs embedded in the analyzed signals, being these IMFs characterized by the same dominant periodicities before and after correction. The effect of correction manifests in the decrease in the energy associated with some IMFs contributing to corrected data. Some IMFs identified by analyzing the ASM-VFM intensity discrepancy are characterized by the same dominant periodicities of those obtained by analyzing the temperature fluctuations of the VFM electronic unit. Thus, the disturbance correlated with the Sun incidence angle could be still present in the corrected magnetic data. Furthermore, the ASM-VFM total intensity difference and the VFM electronic unit temperature display a maximal shared information with a time delay that depends on local time. Taken together, these findings may help to relate the features of the observed VFM-ASM total intensity

  13. [Effect of a constant high intensity magnetic field on reproductive functions in male rats].

    PubMed

    Kokoreva, L V; Chuvpilo, T A; Pustynnikova, A M

    1990-01-01

    In two experiments male rats were exposed to a constant magnetic field (CMF) of 0.4 T either once for 3 hours or 56 times for the same time (throughout the entire spermatogenetic cycle). During the first week after exposure they were mated with untreated females. Some of the females were sacrificed on their 21st day of gestation. The following parameters were measured: percentage of implantations and resorptions, total fetal lethality, number and weight of alive fetuses, weight of placentas and ovaries, hydration of placentas and fetuses. At birth the duration of gestation, the amount of alive and dead newborns, their weight and distribution in the litter were determined. These parameters were used to evaluate the genetic quality of spermatozoa that were involved in fertilization. The pups were observed during the first month of life. The results obtained suggest that mature spermatozoa are resistant to a single CMF exposure and that this exposure causes no mutations in the gametes which may reduce fetal viability. However, chronic exposure to CMF leads to a small and significant increase of preimplantation lethality of fetuses which may indicate a higher frequency of lethal mutations in the gametes.

  14. Intense Plasma Waveguide Terahertz Sources for High-Field THz Probe Science with Ultrafast Lasers for Solid State Physics

    DTIC Science & Technology

    2016-08-25

    AFRL-AFOSR-UK-TR-2016-0029 Intense Plasma-Waveguide Terahertz Sources for High - Field THz probe science with ultrafast lasers for Solid State Physics...SUPPLEMENTARY NOTES 14.  ABSTRACT Project finished successfully 15.  SUBJECT TERMS High - Field THz probe, INTENSE PLASMA-WAVEGUIDE TERAHERTZ SOURCES, Solid State...an existing high energy laser system, has been applied to the study of intense terahertz radiation generated in gaseous plasmas in purpose

  15. Effects of mass media campaign exposure intensity and durability on quit attempts in a population-based cohort study

    PubMed Central

    Wakefield, M. A.; Spittal, M. J.; Yong, H-H.; Durkin, S. J.; Borland, R.

    2011-01-01

    Objective: To assess the extent to which intensity and timing of televised anti-smoking advertising emphasizing the serious harms of smoking influences quit attempts. Methods: Using advertising gross rating points (GRPs), we estimated exposure to tobacco control and nicotine replacement therapy (NRT) advertising in the 3, 4–6, 7–9 and 10–12 months prior to follow-up of a replenished cohort of 3037 Australian smokers during 2002–08. Using generalized estimating equations, we related the intensity and timing of advertising exposure from each source to the likelihood of making a quit attempt in the 3 months prior to follow-up. Results: Tobacco control advertising in the 3-month period prior to follow-up, but not in more distant past periods, was related to a higher likelihood of making a quit attempt. Each 1000 GRP increase per quarter was associated with an 11% increase in making a quit attempt [odds ratio (OR) = 1.11, 95% confidence interval (CI) 1.03–1.19, P = 0.009)]. NRT advertising was unrelated to quit attempts. Conclusions: Tobacco control advertising emphasizing the serious harms of smoking is associated with short-term increases in the likelihood of smokers making a quit attempt. Repeated cycles of higher intensity tobacco control media campaigns are needed to sustain high levels of quit attempts. PMID:21730252

  16. The contribution of temperature, exposure intensity and visible light to the inhibitory effect of irradiation on acute chlamydial infection.

    PubMed

    Marti, Hanna; Blenn, Christian; Borel, Nicole

    2015-12-01

    Water-filtered infrared A (wIRA) is radiation with a spectrum ranging from 780 to 1400 nm. Chlamydiaceae are obligate intracellular bacteria associated with various diseases in both animals and humans. A recent in vitro study demonstrated that wIRA combined with visible light (wIRA/VIS) has potential as a non-chemical method for the treatment of chlamydial infections without adversely affecting the cell viability. The aim of this study was to investigate the influence of various factors on the effect of wIRA/VIS on acute chlamydial infection, namely the impact of temperature, exposure intensity and infectious dose (multiplicity of infection) as well as the efficacy of the visible light component.We demonstrate that non-thermal effects contribute to the inhibition of acute chlamydial infection. Visible light enhances the inhibitory effect of wIRA on extracellular bacteria (elementary bodies or EBs).Moreover, the inhibitory effect of wIRA/VIS following treatment of EBs prior to infection correlated with increased irradiation intensity. The infectivity of mature chlamydial inclusions was significantly reduced upon wIRA/VIS exposure at all irradiation intensities investigated, suggesting the contribution of host cell factors to the anti-chlamydial effect of wIRA/VIS in the late stage of the developmental cycle. The effect of irradiation was not influenced by the infectious dose.

  17. Proteomic analysis of continuous 900-MHz radiofrequency electromagnetic field exposure in testicular tissue: a rat model of human cell phone exposure.

    PubMed

    Sepehrimanesh, Masood; Kazemipour, Nasrin; Saeb, Mehdi; Nazifi, Saeed; Davis, Devra Lee

    2017-05-01

    Although cell phones have been used worldwide, some adverse and toxic effects were reported for this communication technology apparatus. To analyze in vivo effects of exposure to radiofrequency-electromagnetic field (RF-EMF) on protein expression in rat testicular proteome, 20 Sprague-Dawley rats were exposed to 900 MHz RF-EMF for 0, 1, 2, or 4 h/day for 30 consecutive days. Protein content of rat testes was separated by high-resolution two-dimensional electrophoresis using immobilized pH gradient (pI 4-7, 7 cm) and 12% acrylamide and identified by MALDI-TOF/TOF-MS. Two protein spots were found differentially overexpressed (P < 0.05) in intensity and volume with induction factors 1.7 times greater after RF-EMF exposure. After 4 h of daily exposure for 30 consecutive days, ATP synthase beta subunit (ASBS) and hypoxia up-regulated protein 1 precursor (HYOU1) were found to be significantly up-regulated. These proteins affect signaling pathways in rat testes and spermatogenesis and play a critical role in protein folding and secretion in the endoplasmic reticulum. Our results indicate that exposure to RF-EMF produces increases in testicular proteins in adults that are related to carcinogenic risk and reproductive damage. In light of the widespread practice of men carrying phones in their pockets near their gonads, where exposures can exceed as-tested guidelines, further study of these effects should be a high priority.

  18. FIELD COLLECTION METHODS USED IN THE EPA NATIONAL EXPOSURE RESEARCH LABORATORY HUMAN EXPOSURE MEASUREMENT PROGRAM TO EVALUATE CHILDREN'S AGGREGATE EXPOSURE TO PESTICIDES: A TUTORIAL

    EPA Science Inventory

    A tutorial on the field sampling equipment used to collect multimedia samples.

    We conduct observational human exposure measurement studies in order to understand what chemicals people come into contact with, at what levels, what the sources of those chemicals are, and wher...

  19. FIELD COLLECTION METHODS USED IN THE EPA NATIONAL EXPOSURE RESEARCH LABORATORY HUMAN EXPOSURE MEASUREMENT PROGRAM TO EVALUATE CHILDREN'S AGGREGATE EXPOSURE TO PESTICIDES: A TUTORIAL

    EPA Science Inventory

    A tutorial on the field sampling equipment used to collect multimedia samples.

    We conduct observational human exposure measurement studies in order to understand what chemicals people come into contact with, at what levels, what the sources of those chemicals are, and wher...

  20. Modeling high-intensity pulsed electric field inactivation of a lipase from Pseudomonas fluorescens.

    PubMed

    Soliva-Fortuny, R; Bendicho-Porta, S; Martín-Belloso, O

    2006-11-01

    The inactivation kinetics of a lipase from Pseudomonas fluorescens (EC 3.1.1.3.) were studied in a simulated skim milk ultrafiltrate treated with high-intensity pulsed electric fields. Samples were subjected to electric field intensities ranging from 16.4 to 27.4 kV/cm for up to 314.5 micros, thus achieving a maximum inactivation of 62.1%. The suitability of describing experimental data using mechanistic first-order kinetics and an empirical model based on the Weibull distribution function is discussed. In addition, different mathematical expressions relating the residual activity values to field strength and treatment time are supplied. A first-order fractional conversion model predicted residual activity with good accuracy (A(f) = 1.018). A mechanistic insight of the model kinetics was that experimental values were the consequence of different structural organizations of the enzyme, with uneven resistance to the pulsed electric field treatments. The Weibull model was also useful in predicting the energy density necessary to achieve lipase inactivation.

  1. Assessment of magnetic field exposures for a mortality study at a uranium enrichment plant.

    PubMed

    Wenzl, T B

    1999-01-01

    A survey of workplace exposures to 60-Hz magnetic fields was carried out at a large uranium enrichment facility to assign exposures for an updated mortality study. Stratified random selection was used to choose workers for measurement in all jobs and areas, to determine whether consistent distinctions could be made between job groups based on average magnetic field exposures. A total of 252 workdays was measured with a personal monitor, and individual average magnetic field exposures ranged from 0.20 to 82.6 mG. A priori job groups showed significant differences between geometric mean exposures, which ranged from 0.80 to 3.51 mG. Most of these groups showed widely ranging exposures, so they were subdivided based on location and job title to improve the precision of the exposure assignments for the mortality study. These final assignments were made up of 26 groups having arithmetic means ranging from 0.43 to 24.9 mG, with most groups defined by location in addition to job title. In general, electrical maintenance workers did not have elevated magnetic field exposures (> 3 mG), but the exposures of the electricians in switchyard (substation) jobs were elevated. Available employment records did not allow most electricians to be distinguished based on location, so they were assigned exposures based on their plantwide average (above 7 mG). An estimated 9% of the work time of this cohort was spent at daily average exposures above 3 mG, despite the very large electric power consumption at this plant.

  2. Intense laser field effects on the linear and nonlinear intersubband optical properties of a semi-parabolic quantum well

    NASA Astrophysics Data System (ADS)

    Kasapoglu, E.; Duque, C. A.; Sari, H.; Sökmen, I.

    2011-07-01

    By using the compact-density matrix approach, the effect of a nonresonant intense laser field on the linear and nonlinear optical absorptions based on intersubband transitions and the refractive index changes in an asymmetric semiconductor quantum well have been presented. Our results show that the peak position of the absorption coefficient is sensitive to intense laser field, the absorption maximum shifts towards lower energies for increasing intense laser field value. Also we observe as the intense laser field strength increases, the total refractive index change has been increased in magnitude and also shifted towards lower energies. The results indicate that linear and nonlinear optical properties of the low dimensional semiconductor heterostructures can be adjusted in a desired energy range by using intense laser field.

  3. The influence of reduced light intensity on the response of benthic diatoms to herbicide exposure.

    PubMed

    Wood, Rebecca J; Mitrovic, Simon M; Lim, Richard P; Kefford, Ben J

    2016-09-01

    Herbicide pollution events in aquatic ecosystems often coincide with increased turbidity and reduced light intensity. It is therefore important to determine whether reduced light intensity can influence herbicide toxicity, especially to primary producers such as benthic diatoms. Benthic diatoms collected from 4 rivers were exposed to herbicides in 48 h rapid toxicity tests under high light (100 µmol m(-2)  s(-1) ) and low light (20 µmol m(-2)  s(-1) ) intensities. The effects of 2 herbicides (atrazine and glyphosate) were assessed on 26 freshwater benthic diatom taxa. There was no significant interaction of light and herbicide effects at the community level or on the majority (22 of 26) of benthic diatom taxa. This indicates that low light levels will likely have only a minor influence on the response of benthic diatoms to herbicides. Environ Toxicol Chem 2016;35:2252-2260. © 2016 SETAC. © 2016 SETAC.

  4. Review of Studies Concerning Electromagnetic Field (EMF) Exposure Assessment in Europe: Low Frequency Fields (50 Hz–100 kHz)

    PubMed Central

    Gajšek, Peter; Ravazzani, Paolo; Grellier, James; Samaras, Theodoros; Bakos, József; Thuróczy, György

    2016-01-01

    We aimed to review the findings of exposure assessment studies done in European countries on the exposure of the general public to low frequency electric and magnetic fields (EMFs) of various frequencies. The study shows that outdoor average extremely low frequency magnetic fields (ELF-MF) in public areas in urban environments range between 0.05 and 0.2 µT in terms of flux densities, but stronger values (of the order of a few µT) may occur directly beneath high-voltage power lines, at the walls of transformer buildings, and at the boundary fences of substations. In the indoor environment, high values have been measured close to several domestic appliances (up to the mT range), some of which are held close to the body, e.g., hair dryers, electric shavers. Common sources of exposure to intermediate frequencies (IF) include induction cookers, compact fluorescent lamps, inductive charging systems for electric cars and security or anti-theft devices. No systematic measurement surveys or personal exposimetry data for the IF range have been carried out and only a few reports on measurements of EMFs around such devices are mentioned. According to the available European exposure assessment studies, three population exposure categories were classified by the authors regarding the possible future risk analysis. This classification should be considered a crucial advancement for exposure assessment, which is a mandatory step in any future health risk assessment of EMFs exposure. PMID:27598182

  5. Review of Studies Concerning Electromagnetic Field (EMF) Exposure Assessment in Europe: Low Frequency Fields (50 Hz-100 kHz).

    PubMed

    Gajšek, Peter; Ravazzani, Paolo; Grellier, James; Samaras, Theodoros; Bakos, József; Thuróczy, György

    2016-09-01

    We aimed to review the findings of exposure assessment studies done in European countries on the exposure of the general public to low frequency electric and magnetic fields (EMFs) of various frequencies. The study shows that outdoor average extremely low frequency magnetic fields (ELF-MF) in public areas in urban environments range between 0.05 and 0.2 µT in terms of flux densities, but stronger values (of the order of a few µT) may occur directly beneath high-voltage power lines, at the walls of transformer buildings, and at the boundary fences of substations. In the indoor environment, high values have been measured close to several domestic appliances (up to the mT range), some of which are held close to the body, e.g., hair dryers, electric shavers. Common sources of exposure to intermediate frequencies (IF) include induction cookers, compact fluorescent lamps, inductive charging systems for electric cars and security or anti-theft devices. No systematic measurement surveys or personal exposimetry data for the IF range have been carried out and only a few reports on measurements of EMFs around such devices are mentioned. According to the available European exposure assessment studies, three population exposure categories were classified by the authors regarding the possible future risk analysis. This classification should be considered a crucial advancement for exposure assessment, which is a mandatory step in any future health risk assessment of EMFs exposure.

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

    SciTech Connect

    Rogers, W.R.; Smith, H.D.; Orr, J.L.; Reiter, R.J.; Barlow-Walden, L.

    1995-12-31

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

  7. Writing Intensive Undergraduate Field Camp and Education: Expanding the Classroom and Preparing Students for the Workforce

    NASA Astrophysics Data System (ADS)

    Ford, M. T.; McGehee, T. L.

    2014-12-01

    There has always been a strong perception within the geoscience community that a capstone field course was the pinnacle of an undergraduate geoscience degree. Such a course draws from the student's accumulated knowledge base, using information from multiple sub-disciplines to solve "real-world" problems. Since 2006, there has been a 92% increase in students attending field camps (Status of the Geoscience Workforce 2014 - AGI). But, the number of field camps has significantly declined. In 1995, 35% of geoscience departments offered a summer field course but by 2006 that number had dropped to 15% (Status Report on Geoscience Summer Field Camps - AGI) and since 2009, the number of field camps listed in the Geology.com directory has dropped from 100 to about 75. This decline is despite the fact that 88% of industry professionals believe fieldwork should "be an integral and required part of undergraduate programs" (Petcovic, et al., 2014). In 2012, in order to meet the growing needs of industry and better prepare our students, Texas A&M University-Kingsville developed an in-house, unique set of field courses that expand the limits of the classroom. We have two required courses. One is similar to a traditional field camp except that it contains a writing intensive component. The six-credit course runs for seven weeks. Prior to camp, students are required to write an introduction (geologic history section) on the study area. We spend two weeks in the field, mapping daily (Big Bend National Park), and then return to Kingsville. Students then have two weeks to finish a fully referenced paper, including their edited introduction, methods, observations, interpretations, discussion and conclusions and once complete, they begin the introduction for the next area. This is another two-week field session, in central Texas. After this, we return the first paper which has been edited for content by geoscience faculty and for grammar by an English instructor. Students spend the next

  8. Exposure to strong static magnetic field slows the growth of human cancer cells in vitro.

    PubMed

    Raylman, R R; Clavo, A C; Wahl, R L

    1996-01-01

    Proposals to enhance the amount of radiation dose delivered to small tumors with radioimmunotherapy by constraining emitted electrons with very strong homogeneous static magnetic fields has renewed interest in the cellular effects of prolonged exposures to such fields. Past investigations have not studied the effects on tumor cell growth of lengthy exposures to very high magnetic fields. Three malignant human cell lines, HTB 63 (melanoma), HTB 77 IP3 (ovarian carcinoma), and CCL 86 (lymphoma: Raji cells), were exposed to a 7 Tesla uniform static magnetic field for 64 hours. Following exposure, the number of viable cells in each group was determined. In addition, multicycle flow cytometry was performed on all cell lines, and pulsed-field electrophoresis was performed solely on Raji cells to investigate changes in cell cycle patterns and the possibility of DNA fragmentation induced by the magnetic field. A 64 h exposure to the magnetic field produced a reduction in viable cell number in each of the three cell lines. Reductions of 19.04 +/- 7.32%, 22.06 +/- 6.19%, and 40.68 +/- 8.31% were measured for the melanoma, ovarian carcinoma, and lymphoma cell lines, respectively, vs. control groups not exposed to the magnetic field. Multicycle flow cytometry revealed that the cell cycle was largely unaltered. Pulsed-field electrophoresis analysis revealed no increase in DNA breaks related to magnetic field exposure. In conclusion, prolonged exposure to a very strong magnetic field appeared to inhibit the growth of three human tumor cell lines in vitro. The mechanism underlying this effect has not, as yet, been identified, although alteration of cell growth cycle and gross fragmentation of DNA have been excluded as possible contributory factors. Future investigations of this phenomenon may have a significant impact on the future understanding and treatment of cancer.

  9. Radiation Exposure to Staff in Intensive Care Unit with Portable CT Scanner.

    PubMed

    Xie, Zhichao; Liao, Xuelian; Kang, Yan; Zhang, Jiangqian; Jia, Lingli

    2016-01-01

    Background. Bedside radiological procedures pose a risk of radiation exposure to ICU staff. The perception of risk may increase the degree of caution among the health care staff and raise new barriers preventing patients from obtaining prompt care. Objective. The aim of this study was to estimate the annual cumulative radiation dose to individual ICU staff. Methods. In this prospective study, forty subjects were required to wear thermoluminescent dosimeter badges during their working hours. The badges were analyzed to determine the exposure after 3 months. Results. A total of 802 radiological procedures were completed at bedside during the study period. The estimated annual dosage to doctors and nurses on average was 0.99 mSv and 0.88 mSv (p < 0.001), respectively. Residents were subjected to the highest radiation exposure (1.04 mSv per year, p = 0.002). The radiation dose was correlated with day shift working hours (r = 0.426; p = 0.006) and length of service (r = -0.403; p < 0.01). Conclusions. With standard precautions, bedside radiological procedures-including portable CT scans-do not expose ICU staff to high dose of ionizing radiation. The level of radiation exposure is related to the daytime working hours and length of service.

  10. Radiation Exposure to Staff in Intensive Care Unit with Portable CT Scanner

    PubMed Central

    Xie, Zhichao; Liao, Xuelian; Zhang, Jiangqian; Jia, Lingli

    2016-01-01

    Background. Bedside radiological procedures pose a risk of radiation exposure to ICU staff. The perception of risk may increase the degree of caution among the health care staff and raise new barriers preventing patients from obtaining prompt care. Objective. The aim of this study was to estimate the annual cumulative radiation dose to individual ICU staff. Methods. In this prospective study, forty subjects were required to wear thermoluminescent dosimeter badges during their working hours. The badges were analyzed to determine the exposure after 3 months. Results. A total of 802 radiological procedures were completed at bedside during the study period. The estimated annual dosage to doctors and nurses on average was 0.99 mSv and 0.88 mSv (p < 0.001), respectively. Residents were subjected to the highest radiation exposure (1.04 mSv per year, p = 0.002). The radiation dose was correlated with day shift working hours (r = 0.426; p = 0.006) and length of service (r = −0.403; p < 0.01). Conclusions. With standard precautions, bedside radiological procedures—including portable CT scans—do not expose ICU staff to high dose of ionizing radiation. The level of radiation exposure is related to the daytime working hours and length of service. PMID:27556036

  11. Investigating short-term exposure to electromagnetic fields on reproductive capacity of invertebrates in the field situation.

    PubMed

    Vijver, Martina G; Bolte, John F B; Evans, Tracy R; Tamis, Wil L M; Peijnenburg, Willie J G M; Musters, C J M; de Snoo, Geert R

    2014-01-01

    Organisms are exposed to electromagnetic fields from the introduction of wireless networks that send information all over the world. In this study we examined the impact of exposure to the fields from mobile phone base stations (GSM 900 MHz) on the reproductive capacity of small, virgin, invertebrates. A field experiment was performed exposing four different invertebrate species at different distances from a radiofrequency electromagnetic fields (RF EMF) transmitter for a 48-h period. The control groups were isolated from EMF exposure by use of Faraday cages. The response variables as measured in the laboratory were fecundity and number of offspring. Results showed that distance was not an adequate proxy to explain dose-response regressions. No significant impact of the exposure matrices, measures of central tendency and temporal variability of EMF, on reproductive endpoints was found. Finding no impact on reproductive capacity does not fully exclude the existence of EMF impact, since mechanistically models hypothesizing non-thermal-induced biological effects from RF exposure are still to be developed. The exposure to RF EMF is ubiquitous and is still increasing rapidly over large areas. We plea for more attention toward the possible impacts of EMF on biodiversity.

  12. Space-time contours to treat intense field-dressed molecular states. I. Theory

    NASA Astrophysics Data System (ADS)

    Sarkar, Biplab; Adhikari, Satrajit; Baer, Michael

    2007-07-01

    A molecular system exposed to an intense external field is considered. The strength of the field is measured by the number L of electronic states that become populated during this process. In the present article the authors discuss a rigorous way, based on the recently introduced space-time contours [R. Baer, et al., J. Chem. Phys. 119, 6998 (2003)], to form N coupled Schrödinger equations where N field-free states forms a Hilbert subspace in the spatial region of interest. From previous studies it is known that a group of states forms a Hilbert subspace if and only if the corresponding topological D matrix is diagonal [M. Baer, et al., Farad, Discuss 127, 337 (2004)].

  13. Drift waves, intense parallel electric fields, and turbulence associated with asymmetric magnetic reconnection at the magnetopause

    NASA Astrophysics Data System (ADS)

    Ergun, R. E.; Chen, L.-J.; Wilder, F. D.; Ahmadi, N.; Eriksson, S.; Usanova, M. E.; Goodrich, K. A.; Holmes, J. C.; Sturner, A. P.; Malaspina, D. M.; Newman, D. L.; Torbert, R. B.; Argall, M. R.; Lindqvist, P.-A.; Burch, J. L.; Webster, J. M.; Drake, J. F.; Price, L.; Cassak, P. A.; Swisdak, M.; Shay, M. A.; Graham, D. B.; Strangeway, R. J.; Russell, C. T.; Giles, B. L.; Dorelli, J. C.; Gershman, D.; Avanov, L.; Hesse, M.; Lavraud, B.; Le Contel, O.; Retino, A.; Phan, T. D.; Goldman, M. V.; Stawarz, J. E.; Schwartz, S. J.; Eastwood, J. P.; Hwang, K.-J.; Nakamura, R.; Wang, S.

    2017-04-01

    Observations of magnetic reconnection at Earth's magnetopause often display asymmetric structures that are accompanied by strong magnetic field (B) fluctuations and large-amplitude parallel electric fields (E||). The B turbulence is most intense at frequencies above the ion cyclotron frequency and below the lower hybrid frequency. The B fluctuations are consistent with a thin, oscillating current sheet that is corrugated along the electron flow direction (along the X line), which is a type of electromagnetic drift wave. Near the X line, electron flow is primarily due to a Hall electric field, which diverts ion flow in asymmetric reconnection and accompanies the instability. Importantly, the drift waves appear to drive strong parallel currents which, in turn, generate large-amplitude ( 100 mV/m) E|| in the form of nonlinear waves and structures. These observations suggest that turbulence may be common in asymmetric reconnection, penetrate into the electron diffusion region, and possibly influence the magnetic reconnection process.

  14. Optoelectrofluidic field separation based on light-intensity gradients and its applications

    NASA Astrophysics Data System (ADS)

    Yoon, Jinsung; Lee, Sanghyun; Kang, Kwan Hyoung

    2010-11-01

    Optoelectrofluidic field separation (OEFS) of particles under light-intensity gradient (LIG) is reported, where the LIG illumination on the photoconductive layer converts the short-ranged dielectrophoresis (DEP) force to the long-ranged one. The long-ranged DEP force can compete with the hydrodynamic force by alternating current electro-osmosis (ACEO) over the entire illumination area for realizing effective field separation of particles. Results of the field separation and concentration of diverse particle pairs (0.82--16 μm) are well demonstrated, and conditions determining the critical radius and effective particle manipulation are discussed. In addition, expanding the OEFS to biological applications such as rapid cell manipulation and separation will be discussed. The OEFS with LIG strategy could be a promising manipulation method of particles including biological cells in many applications where a rapid manipulation of particles over the entire working area is of interest.

  15. Attosecond control of spin polarization in electron-ion recollision driven by intense tailored fields

    NASA Astrophysics Data System (ADS)

    Ayuso, David; Jiménez-Galán, Alvaro; Morales, Felipe; Ivanov, Misha; Smirnova, Olga

    2017-07-01

    Tunnel ionization of noble gas atoms driven by a strong circularly polarized laser field in combination with a counter-rotating second harmonic generates spin-polarized electrons correlated to the spin-polarized ionic core. Crucially, such two-color field can bring the spin-polarized electrons back to the parent ion, enabling the scattering of the spin-polarized electron on the spin-polarized parent ion. Here we show how one can control the degree of spin polarization as a function of electron energy and recollision time by tuning the laser parameters, such as the relative intensities of the counter-rotating fields. The attosecond precision of the control over the degree of spin polarization opens the door for attosecond control and spectroscopy of spin-resolved dynamics.

  16. Early studies on the biological effects of high-intensity magnetic fields.

    PubMed

    Soria, E D; Fine, E J

    1992-10-01

    In 1892, Frederick Peterson described the experiences of humans exposed to magnetic fields of strength comparable to those currently used in magnetic resonance imaging. These investigations were conducted in the Edison Laboratory. None of the subjects exposed to constant and to time-variable magnetic fields suffered any ill effects. Peterson concluded that the human organism was in no way appreciably affected by the most powerful magnets known to nineteenth-century science. Peterson can be credited with the first truly scientific assessment of the biological effects of high-intensity magnetic fields. His experiments on humans, done one century ago with great cogency and skill, provide a source of inspiration to modern studies on magnetic resonance imaging.

  17. Method for measuring specific heats in intense magnetic fields at low temperatures using capacitance thermometry

    NASA Astrophysics Data System (ADS)

    Lawless, W. N.; Clark, C. F.; Arenz, R. W.

    1982-11-01

    A drift method is described for measuring specific heats in intense magnetic fields at low temperatures. Capacitance thermometry is used, and an automated data-collection system utilizes the imbalance of a transformer-ratio-arm bridge to process the capacitance data. The zero-field specific heat must be known, and measurement of the in situ drift in zero-field calibrates the thermal link. Additional calibration of the link is required if the link's magnetothermal conductivity effects are significant, and a specific example of a copper-wire link is presented. The method resolves complex structure in the specific heat near a steep λ-type anomaly, as illustrated by measurements on a chromite spinel at 7.5 T. The uncertainty in the method is estimated to be ≂±7%.

  18. Lightning criteria relative to space shuttles: Currents and electric field intensity in Florida lightning

    NASA Technical Reports Server (NTRS)

    Uman, M. A.; Mclain, D. K.

    1972-01-01

    The measured electric field intensities of 161 lightning strokes in 39 flashes which occurred between 1 and 35 km from an observation point at Kennedy Space Center, Florida during June and July of 1971 have been analyzed to determine the lightning channel currents which produced the fields. In addition, typical channel currents are derived and from these typical electric fields at distances between 0.5 and 100 km are computed and presented. On the basis of the results recommendations are made for changes in the specification of lightning properties relative to space vehicle design as given in NASA TMX-64589 (Daniels, 1971). The small sample of lightning analyzed yielded several peak currents in the 100 kA range. Several current rise-times from zero to peak of 0.5 microsec or faster were found; and the fastest observed current rate-of-rise was near 200 kA/microsec. The various sources of error are discussed.

  19. Influence of electromagnetic field intensity on the metastable zone width of CaCO3 crystallization in circulating water

    NASA Astrophysics Data System (ADS)

    Wang, Jianguo; Liang, Yandong; Chen, Si

    2016-09-01

    In this study, changes in the metastable zone width of CaCO3 crystallization was determined through conductivity titration by altering electromagnetic field parameters applied to the circulating water system. The critical conductivity value and metastable zone curves of CaCO3 crystallization were determined under different solution concentrations and electromagnetic field intensities. Experimental results indicate that the effect of the electromagnetic field intensity on the critical conductivity value intensifies with the increase of solution concentration. Moreover, the metastable zone width of CaCO3 crystallization increases with the increase of electromagnetic field intensity within 200 Gs, thereby prolonging the induction period of nucleation.

  20. Acceleration of electrons by a circularly polarized laser pulse in the presence of an intense axial magnetic field in vacuum

    SciTech Connect

    Singh, K. P.

    2006-08-15

    Acceleration of electrons by a circularly polarized laser pulse in the presence of a short duration intense axial magnetic field has been studied. Resonance occurs between the electrons and the laser field for an optimum magnetic field leading to effective energy transfer from laser to electrons. The value of optimum magnetic field is independent of the laser intensity and decreases with initial electron energy. The electrons rotate around the axis of the laser pulse with small angle of emittance and small energy spread. Acceleration gradient increases with laser intensity and decreases with initial electron energy.

  1. An Active Contour Model for the Segmentation of Images with Intensity Inhomogeneities and Bias Field Estimation

    PubMed Central

    Huang, Chencheng; Zeng, Li

    2015-01-01

    Intensity inhomogeneity causes many difficulties in image segmentation and the understanding of magnetic resonance (MR) images. Bias correction is an important method for addressing the intensity inhomogeneity of MR images before quantitative analysis. In this paper, a modified model is developed for segmenting images with intensity inhomogeneity and estimating the bias field simultaneously. In the modified model, a clustering criterion energy function is defined by considering the difference between the measured image and estimated image in local region. By using this difference in local region, the modified method can obtain accurate segmentation results and an accurate estimation of the bias field. The energy function is incorporated into a level set formulation with a level set regularization term, and the energy minimization is conducted by a level set evolution process. The proposed model first appeared as a two-phase model and then extended to a multi-phase one. The experimental results demonstrate the advantages of our model in terms of accuracy and insensitivity to the location of the initial contours. In particular, our method has been applied to various synthetic and real images with desirable results. PMID:25837416

  2. Ligand field and Judd-Ofelt intensity parameters of samarium doped tellurite glass

    NASA Astrophysics Data System (ADS)

    Tanko, Y. A.; Ghoshal, S. K.; Sahar, M. R.

    2016-08-01

    We report the samarium ions (Sm3+) contents dependent ligand field and Judd-Ofelt (JO) intensity parameters (Ω2, Ω4, Ω6) of zinc tellurite glass. The amorphous nature of the melt-quench synthesized glasses is confirmed using XRD. The lower energy region of the absorption spectra is used to calculate JO intensity parameters and the UV edge is exploited to determine the Nephelauxetic ratio, bonding, and Racah parameters. The Nephelauxetic ratio and Racah parameter is reduced and the bonding parameter is enhanced with the increase of Sm3+ concentration. The enhancement in covalency is found to increase the non-bridging oxygen and crystal field strength by delocalizing more d-shell electrons. Furthermore, Nephelauxetic function revealed an increase due to the reduction of localized d-electrons that is aroused from the overlap of d-orbital and ligand orbital. The JO intensity parameters displayed the Ω4>Ω6>Ω2 trend. Increase in Ω2 and decrease in Ω2 and Ω2 with the increase of Sm3+ concentration indicated an increase in the Smsbnd O covalency and coordination in the asymmetry of the prepared glasses. The large vale of spectroscopic quality factor (greater than unity) makes the proposed glass system prospective for various optical devices fabrication.

  3. Spatial correlation of the high intensity zone in deep-water acoustic field

    NASA Astrophysics Data System (ADS)

    Li, Jun; Li, Zheng-Lin; Ren, Yun

    2016-12-01

    The spatial correlations of acoustic field have important implications for underwater target detection and other applications in deep water. In this paper, the spatial correlations of the high intensity zone in the deep-water acoustic field are investigated by using the experimental data obtained in the South China Sea. The experimental results show that the structures of the spatial correlation coefficient at different ranges and depths are similar to the transmission loss structure in deep water. The main reason for this phenomenon is analyzed by combining the normal mode theory with the ray theory. It is shown that the received signals in the high intensity zone mainly include one or two main pulses which are contributed by the interference of a group of waterborne modes with similar phases. The horizontal-longitudinal correlations at the same receiver depth but in different high intensity zones are analyzed. At some positions, more pulses are received in the arrival structure of the signal due to bottom reflection and the horizontal-longitudinal correlation coefficient decreases accordingly. The multi-path arrival structure of receiving signal becomes more complex with increasing receiver depth. Project supported by the National Natural Science Foundation of China (Grant Nos. 11434012 and 41561144006).

  4. Acoustic energy density distribution and sound intensity vector field inside coupled spaces.

    PubMed

    Meissner, Mirosław

    2012-07-01

    In this paper, the modal expansion method supported by a computer implementation has been used to predict steady-state distributions of the potential and kinetic energy densities, and the active and reactive sound intensities inside two coupled enclosures. The numerical study was dedicated to low-frequency room responses. Calculation results have shown that the distribution of energetic quantities in coupled spaces is strongly influenced by the modal localization. Appropriate descriptors of the localization effect were introduced to identify localized modes. As was evidenced by numerical data, the characteristic objects in the active intensity field are vortices positioned irregularly inside the room. It was found that vortex centers lie exactly on the lines corresponding to zeros of the eigenfunction for a dominant mode. Finally, an impact of the wall impedance on the quantitative relationship between the active and reactive intensities was analyzed and it was concluded that for very small sound damping the behavior of the sound intensity inside the room space is essentially only oscillatory.

  5. An inverse method for estimation of the acoustic intensity in the focused ultrasound field

    NASA Astrophysics Data System (ADS)

    Yu, Ying; Shen, Guofeng; Chen, Yazhu

    2017-03-01

    Recently, a new method which based on infrared (IR) imaging was introduced. Authors (A. Shaw, et al and M. R. Myers, et al) have established the relationship between absorber surface temperature and incident intensity during the absorber was irradiated by the transducer. Theoretically, the shorter irradiating time makes estimation more in line with the actual results. But due to the influence of noise and performance constrains of the IR camera, it is hard to identify the difference in temperature with short heating time. An inverse technique is developed to reconstruct the incident intensity distribution using the surface temperature with shorter irradiating time. The algorithm is validated using surface temperature data generated numerically from three-layer model which was developed to calculate the acoustic field in the absorber, the absorbed acoustic energy during the irradiation, and the consequent temperature elevation. To assess the effect of noisy data on the reconstructed intensity profile, in the simulations, the different noise levels with zero mean were superposed on the exact data. Simulation results demonstrate that the inversion technique can provide fairly reliable intensity estimation with satisfactory accuracy.

  6. Exposure to electromagnetic fields and suicide among electric utility workers: a nested case-control study

    PubMed Central

    van Wijngaarden, E.; Savitz, D.; Kleckner, R.; Cai, J.; Loomis, D.

    2000-01-01

    OBJECTIVES—This nested case-control study examines mortality from suicide in relation to estimated exposure to extremely low frequency electromagnetic fields (EMFs) in a cohort of 138 905 male electric utility workers.
METHODS—Case-control sampling included 536 deaths from suicide and 5348 eligible controls. Exposure was classified based on work in the most common jobs with increased exposure to magnetic fields and indices of cumulative exposure to magnetic fields based on a measurement survey.
RESULTS—Suicide mortality was increased relative to work in exposed jobs and with indices of exposure to magnetic fields. Increased odds ratios (ORs) were found for years of employment as an electrician (OR 2.18; 95% confidence interval (95% CI) 1.25 to 3.80) or lineman (OR 1.59; 95% CI 1.18 to 2.14), whereas a decreased OR was found for power p