Science.gov

Sample records for level ionising radiation

  1. Migration levels of PVC plasticisers: Effect of ionising radiation treatment.

    PubMed

    Zygoura, Panagiota D; Paleologos, Evangelos K; Kontominas, Michael G

    2011-09-01

    Migration levels of commercial plasticisers [di-(2-ethylhexyl) adipate (DEHA) and acetyl tributyl citrate (ATBC)] from polyvinyl chloride (PVC) film into the EU specified aqueous food simulants (distilled water, 3% w/v acetic acid and 10% v/v ethanol) were monitored as a function of time. Migration testing was carried out at 40°C for 10days (EEC, 1993). Determination of the analytes was performed by applying the analytical methodology based on surfactant (Triton X-114) mediated extraction prior to gas chromatographic-flame ionisation detection (GC-FID) recently proposed by our group. The study focuses on the determination of the effect of gamma radiation on plasticiser migration into the selected simulants. PVC cling film used was subjected to ionising treatment with a [(60)Co] source at doses equal to 5, 15 and 25kGy. DEHA and ATBC migration into the EU aqueous simulating solvents was limited, yielding final concentrations in the respective ranges 10-100μg/l and 171-422μg/l; hence, ATBC demonstrated a stronger interaction with all three simulants compared to DEHA. Migration data, with respect to ATBC, showed that the most aggressive simulant seemed to be the 10% ethanol, while in the case of DEHA the 3% aqueous acetic acid exhibited the highest extraction efficiency; distilled water demonstrated the lowest migration in both cases. With regard to PVC treatment with gamma rays, high radiation doses up to 25kGy produced a statistically significant (p<0.05) effect on the migration of both plasticisers.

  2. European Code against Cancer 4th Edition: Ionising and non-ionising radiation and cancer.

    PubMed

    McColl, Neil; Auvinen, Anssi; Kesminiene, Ausrele; Espina, Carolina; Erdmann, Friederike; de Vries, Esther; Greinert, Rüdiger; Harrison, John; Schüz, Joachim

    2015-12-01

    Ionising radiation can transfer sufficient energy to ionise molecules, and this can lead to chemical changes, including DNA damage in cells. Key evidence for the carcinogenicity of ionising radiation comes from: follow-up studies of the survivors of the atomic bombings in Japan; other epidemiological studies of groups that have been exposed to radiation from medical, occupational or environmental sources; experimental animal studies; and studies of cellular responses to radiation. Considering exposure to environmental ionising radiation, inhalation of naturally occurring radon is the major source of radiation in the population - in doses orders of magnitude higher than those from nuclear power production or nuclear fallout. Indoor exposure to radon and its decay products is an important cause of lung cancer; radon may cause approximately one in ten lung cancers in Europe. Exposures to radon in buildings can be reduced via a three-step process of identifying those with potentially elevated radon levels, measuring radon levels, and reducing exposure by installation of remediation systems. In the 4th Edition of the European Code against Cancer it is therefore recommended to: "Find out if you are exposed to radiation from naturally high radon levels in your home. Take action to reduce high radon levels". Non-ionising types of radiation (those with insufficient energy to ionise molecules) - including extremely low-frequency electric and magnetic fields as well as radiofrequency electromagnetic fields - are not an established cause of cancer and are therefore not addressed in the recommendations to reduce cancer risk.

  3. Background ionising radiation: a pictorial perspective.

    PubMed

    Bibbo, Giovanni; Piotto, Lino

    2014-09-01

    Ionising radiation from natural sources, known as background radiation, has existed on earth since the earth's formation. The exposure of humans and other living creatures to this radiation is a feature of the earth's environment which is continuing and inescapable. The word "radiation" brings fear to many people: a fear of the unknown, as human's senses cannot detect the presence of ionising radiation. In this study, a catalogue of images of the distribution of radioactivity in every day objects and foods has been produced using an imaging plate from a computed radiography cassette. The aim of the study is that by visually demonstrating that every day objects and foods are radioactive would alleviate the fear of "radiation" by becoming aware that we live in a radioactive environment and even our body is radioactive.

  4. Dosimetry of ionising radiation in modern radiation oncology

    NASA Astrophysics Data System (ADS)

    Kron, Tomas; Lehmann, Joerg; Greer, Peter B.

    2016-07-01

    Dosimetry of ionising radiation is a well-established and mature branch of physical sciences with many applications in medicine and biology. In particular radiotherapy relies on dosimetry for optimisation of cancer treatment and avoidance of severe toxicity for patients. Several novel developments in radiotherapy have introduced new challenges for dosimetry with small and dynamically changing radiation fields being central to many of these applications such as stereotactic ablative body radiotherapy and intensity modulated radiation therapy. There is also an increasing awareness of low doses given to structures not in the target region and the associated risk of secondary cancer induction. Here accurate dosimetry is important not only for treatment optimisation but also for the generation of data that can inform radiation protection approaches in the future. The article introduces some of the challenges and highlights the interdependence of dosimetric calculations and measurements. Dosimetric concepts are explored in the context of six application fields: reference dosimetry, small fields, low dose out of field, in vivo dosimetry, brachytherapy and auditing of radiotherapy practice. Recent developments of dosimeters that can be used for these purposes are discussed using spatial resolution and number of dimensions for measurement as sorting criteria. While dosimetry is ever evolving to address the needs of advancing applications of radiation in medicine two fundamental issues remain: the accuracy of the measurement from a scientific perspective and the importance to link the measurement to a clinically relevant question. This review aims to provide an update on both of these.

  5. IEC standards for individual monitoring of ionising radiation.

    PubMed

    Voytchev, M; Ambrosi, P; Behrens, R; Chiaro, P

    2011-03-01

    This paper presents IEC/SC 45B 'Radiation protection instrumentation' and its standards for individual monitoring of ionising radiation: IEC 61526 Ed. 3 for active personal dosemeters and IEC 62387-1 for passive integrating dosimetry systems. The transposition of these standards as CENELEC (European) standards is also discussed together with the collaboration between IEC/SC 45B and ISO/TC 85/SC 2.

  6. IEC STANDARDS FOR INDIVIDUAL MONITORING OF IONISING RADIATION

    SciTech Connect

    Voytchev, Miroslav; Ambrosi, P.; Behrens, R.; Chiaro Jr, Peter John

    2011-01-01

    This paper presents IEC/SC 45B Radiation protection instrumentation and its standards for individual monitoring of ionising radiation: IEC 61526 Ed. 3 for active personal dosemeters and IEC 62387-1 for passive integrating dosimetry systems. The transposition of these standards as CENELEC (European) standards is also discussed together with the collaboration between IEC/SC 45B and ISO/TC 85/SC 2.

  7. Resonance laser-induced ionisation of sodium vapour taking radiative transfer into account

    SciTech Connect

    Kosarev, N I; Shaparev, N Ya

    2006-04-30

    The problem of ionisation of atomic sodium in the field of resonance laser radiation is numerically solved taking radiative transfer into account. Seed electrons are produced due to the mechanism of associative ionisation, then they gain energy in superelastic processes (collisions of the second kind) and initiate the avalanche ionisation of the medium by electron impact. We studied the effect of secondary radiation on the laser pulse propagation upon competition between the ionising and quenching electron collisions with excited atoms, on the kinetics of ionisation-induced vapour bleaching, and the plasma channel expansion in the form of a halo. (interaction of laser radiation with matter)

  8. Feedback regulated escape of ionising radiation from high redshift galaxies

    NASA Astrophysics Data System (ADS)

    Trebitsch, M.; Blaizot, J.

    2016-12-01

    Small galaxies are thought to provide the bulk of the radiation necessary to reionise the Universe by z ˜ 6. Their ionising efficiency is usually quantified by their escape fraction f_{esc}, but it is extremely hard to constrain from observations. With the goal of studying the physical processes that determine the values of the escape fraction, we have run a series of high resolution, cosmological, radiative hydrodynamics simulations centred on three galaxies. We find that the variability of the escape fraction follows that of the star formation rate, and that local feedback is necessary for radiation to escape.

  9. Laboratory astrophysics experiments relating to ionising and weakly radiative shocks

    NASA Astrophysics Data System (ADS)

    Cross, Joseph; Foster, John; Graham, Peter; Busschaert, Clotilde; Charpentier, Nicolas; Danson, Colin; Doyle, Hugo; Drake, R. Paul; Falize, Emeric; Fyrth, Jim; Gumbrell, Edward; Koenig, Michel; Kuranz, Carolyn; Loupias, Berenice; Michaut, Claire; Patankar, Sid; Skidmore, Jonathan; Spindloe, Christopher; Tubman, Ellie; Woolsey, Nigel; Yurchak, Roman; Gregori, Gianluca

    2014-10-01

    The aim of the POLAR project is to simulate, in the laboratory, the accretion shock region of a magnetic cataclysmic variable binary star system. Scaling laws have shown that laser experiments can be related to astrophysical phenomena by matching relevant dimensionless parameters. As well as forming a reverse shock, relevant to the POLAR project, the experimental system is also likely formed of a weakly radiating shock and an ionisation front. Results from our experiment at the Orion Laser are presented here, alongside comparisons to simulation and the astrophysical case (of relevance to triggered star formation).

  10. INTERACTION OF LASER RADIATION WITH MATTER: Resonance laser-induced ionisation of sodium vapour taking radiative transfer into account

    NASA Astrophysics Data System (ADS)

    Kosarev, N. I.; Shaparev, N. Ya

    2006-04-01

    The problem of ionisation of atomic sodium in the field of resonance laser radiation is numerically solved taking radiative transfer into account. Seed electrons are produced due to the mechanism of associative ionisation, then they gain energy in superelastic processes (collisions of the second kind) and initiate the avalanche ionisation of the medium by electron impact. We studied the effect of secondary radiation on the laser pulse propagation upon competition between the ionising and quenching electron collisions with excited atoms, on the kinetics of ionisation-induced vapour bleaching, and the plasma channel expansion in the form of a halo.

  11. Binary-Encounter-Bethe ionisation cross sections for simulation of DNA damage by the direct effect of ionising radiation.

    PubMed

    Plante, I; Cucinotta, F A

    2015-09-01

    DNA damage is of crucial importance in the understanding of the effects of ionising radiation. To refine existing DNA damage models, an approach using the Binary-Encounter-Bethe (BEB) cross sections was developed. The differential cross sections for ionisation of the molecular orbitals of the DNA bases, sugars and phosphates are calculated using the electron binding energy, the mean kinetic energy and the occupancy number of each orbital as parameters. The resulting cross section has an analytic form which is quite convenient to use for Monte-Carlo codes that randomly sample the energy loss occurring during an ionisation event. We also describe an algorithm to simulate the interactions of electrons with DNA in the radiation transport code RITRACKS using the integrated BEB cross section for the bases, sugar and phosphates.

  12. Hazards of ionising radiation: 100 years of observations on man.

    PubMed Central

    Doll, R.

    1995-01-01

    In November 1895, when Conrad Röntgen serendipitously discovered X-rays, epidemiology was effectively limited to the study of infectious disease. What little epidemiological work was done in other fields was done as part of clinical medicine or under the heading of geographical pathology. The risks from exposure to X-rays and subsequently from other types of ionising radiation were consequently discovered by qualitative association or animal experiment. They did not begin to be quantified in humans until half a century later, when epidemiology emerged as a scientific discipline capable of quantifying risks of non-infectious disease and the scientific world was alerted to the need for assessing the effects of the radiation to which large populations might be exposed by the use of nuclear energy in peace and war. PMID:8519643

  13. Occupational exposure to ionising radiation and mortality among workers of the former Spanish Nuclear Energy Board.

    PubMed Central

    Rodríguez Artalejo, F; Castaño Lara, S; de Andrés Manzano, B; García Ferruelo, M; Iglesias Martín, L; Calero, J R

    1997-01-01

    OBJECTIVES: Firstly, to ascertain whether mortality among workers of the former Spanish Nuclear Energy Board (Junta de Energía Nuclear-JEN) was higher than that for the Spanish population overall; and secondly, if this were so, to ascertain whether this difference was associated with exposure to ionising radiation. METHODS: A retrospective follow up of a cohort of 5657 workers was carried out for the period 1954-92. Cohort mortality was compared with that for the Spanish population overall, with standardised mortality ratios (SMRs) adjusted for sex, age, and calendar period. Also, Poisson models were used to analyse mortality from lung cancer in the cohort by level of exposure to ionising radiation. RESULTS: Workers' median and mean cumulative exposures were 4.04 and 11.42 mSv, respectively. Mean annual exposure was 1.33 mSv. Excess mortality due to bone tumours was found for the cohort as a whole (six deaths observed; SMR 2.95; 95% confidence interval (95% CI) 1.08 to 6.43). Among miners, excess mortality was found for non-malignant respiratory diseases (SMR 2.94; 95% CI 2.27 to 3.75), and for lung cancer bordering on statistical significance (SMR 1.50; 95% CI 0.96 to 2.23; P = 0.055). Relative risks of dying of lung cancer from ionising radiation in the dose quartiles 2, 3, and 4 versus the lowest dose quartile, were 1.00, 1.64, and 0.94, respectively. CONCLUSIONS: Excess mortality from lung cancer was found among JEN miners. Nevertheless, no clear relation was found between mortality from lung cancer and level of exposure to ionising radiation in the JEN cohort. Continued follow up of the cohort is required to confirm excess mortality from bone tumours. PMID:9155782

  14. Medical effects and risks of exposure to ionising radiation.

    PubMed

    Mettler, Fred A

    2012-03-01

    Effects and risk from exposure to ionising radiation depend upon the absorbed dose, dose rate, quality of radiation, specifics of the tissue irradiated and other factors such as the age of the individual. Effects may be apparent almost immediately or may take decades to be manifest. Cancer is the most important stochastic effect at absorbed doses of less than 1 Gy. The risk of cancer induction varies widely across different tissues; however, the risk of fatal radiation-induced cancer for a general population following chronic exposure is about 5% Sv(-1). Quantification of cancer risk at doses of less than 0.1 Gy remains problematic. Hereditary risks from irradiation that might result in effects to offspring of humans appear to be much lower and any such potential risks can only be estimated from animal models. At high doses (over 1 Gy) cell killing and modification causes deterministic effects such as skin burns, and bone marrow depression, in which case immunosuppression becomes a critical issue. Acute whole body penetrating gamma irradiation at doses in excess of 2 Gy results in varying degrees of acute radiation sickness and doses over 10 Gy are usually lethal as a result of combined organ injury.

  15. Comparison of low and high dose ionising radiation using topological analysis of gene coexpression networks

    PubMed Central

    2012-01-01

    Background The growing use of imaging procedures in medicine has raised concerns about exposure to low-dose ionising radiation (LDIR). While the disastrous effects of high dose ionising radiation (HDIR) is well documented, the detrimental effects of LDIR is not well understood and has been a topic of much debate. Since little is known about the effects of LDIR, various kinds of wet-lab and computational analyses are required to advance knowledge in this domain. In this paper we carry out an “upside-down pyramid” form of systems biology analysis of microarray data. We characterised the global genomic response following 10 cGy (low dose) and 100 cGy (high dose) doses of X-ray ionising radiation at four time points by analysing the topology of gene coexpression networks. This study includes a rich experimental design and state-of-the-art computational systems biology methods of analysis to study the differences in the transcriptional response of skin cells exposed to low and high doses of radiation. Results Using this method we found important genes that have been linked to immune response, cell survival and apoptosis. Furthermore, we also were able to identify genes such as BRCA1, ABCA1, TNFRSF1B, MLLT11 that have been associated with various types of cancers. We were also able to detect many genes known to be associated with various medical conditions. Conclusions Our method of applying network topological differences can aid in identifying the differences among similar (eg: radiation effect) yet very different biological conditions (eg: different dose and time) to generate testable hypotheses. This is the first study where a network level analysis was performed across two different radiation doses at various time points, thereby illustrating changes in the cellular response over time. PMID:22594378

  16. Teaching about Radioactivity and Ionising Radiation: An Alternative Approach.

    ERIC Educational Resources Information Center

    Millar, Robin; And Others

    1990-01-01

    Children's ideas about radiation and radioactivity are reviewed and several common areas of misunderstanding are identified. An approach to teaching the topic at the secondary school level which seeks to specifically address known difficulties is outlined. (CW)

  17. Multidisciplinary approach to assess the sensitivity of dwarf tomato plants to low-LET ionising radiation

    NASA Astrophysics Data System (ADS)

    De Micco, Veronica; De Pascale, Stefania; Aronne, Giovanna; Paradiso, Roberta; Vitaglione, Paola; Turano, Mimmo; Arena, Carmen

    Ionising radiation, acting alone or in interaction with microgravity and other environmental constraints, may affect plant at molecular, morpho-structural and physiological level. The intensity of the plant’s response depends on the properties of radiation and on the features of the plant itself. Indeed, different species are characterised by different susceptibility to radiation which may change during the life course. The aim of this research was to study the radiosensitivity to low-LET ionising radiation of plants of dwarf tomato (Solanum lycopersicum L. ‘Microtom’) at two phenological phases (vegetative and reproductive), within the purpose of analysing plants for consideration as candidates for Bioregenerative Life Support Systems (BLSS) in Space. To pursue this objective, plants of the cultivar Microtom were irradiated with different doses of X-rays either at the stage of the second true leaf (VP - vegetative phase) or when at least one flower was blossomed (RP - reproductive phase). Plant’s response to ionising radiation was assessed through a multidisciplinary approach combining genetic analyses, ecophysiological measurements, morpho-anatomical characterisation of leaves and fruits, nutritional analyses of fruits. Growth, molecular and morpho-functional traits were measured during plant development up to fruiting in both VP and RP plant groups, and compared with non-irradiated control plants. Plant growth was monitored weekly recording parameters such as plant height, number of leaves, leaf area, flowering and fruiting rate. Potential DNA alterations were explored through Random Amplified Polymorphic DNA (RAPD) technique. The efficiency of the photosynthetic apparatus was evaluated by determining photosynthetic pigment composition, photochemistry and leaf gas exchanges. Leaf and fruit structure were analysed through light and epi-fluorescence microscopy. Leaf anatomical traits related to photosynthetic efficiency, and to structural radioprotection

  18. The biological effects of ionising radiation on Crustaceans: A review.

    PubMed

    Fuller, Neil; Lerebours, Adélaïde; Smith, Jim T; Ford, Alex T

    2015-10-01

    Historic approaches to radiation protection are founded on the conjecture that measures to safeguard humans are adequate to protect non-human organisms. This view is disparate with other toxicants wherein well-developed frameworks exist to minimise exposure of biota. Significant data gaps for many organisms, coupled with high profile nuclear incidents such as Chernobyl and Fukushima, have prompted the re-evaluation of our approach toward environmental radioprotection. Elucidating the impacts of radiation on biota has been identified as priority area for future research within both scientific and regulatory communities. The crustaceans are ubiquitous in aquatic ecosystems, comprising greater than 66,000 species of ecological and commercial importance. This paper aims to assess the available literature of radiation-induced effects within this subphylum and identify knowledge gaps. A literature search was conducted pertaining to radiation effects on four endpoints as stipulated by a number of regulatory bodies: mortality, morbidity, reproduction and mutation. A major finding of this review was the paucity of data regarding the effects of environmentally relevant radiation doses on crustacean biology. Extremely few studies utilising chronic exposure durations or wild populations were found across all four endpoints. The dose levels at which effects occur was found to vary by orders of magnitude thus presenting difficulties in developing phyla-specific benchmark values and reference levels for radioprotection. Based on the limited data, mutation was found to be the most sensitive endpoint of radiation exposure, with mortality the least sensitive. Current phyla-specific dose levels and limits proposed by major regulatory bodies were found to be inadequate to protect species across a range of endpoints including morbidity, mutation and reproduction and examples are discussed within. These findings serve to prioritise areas for future research that will significantly

  19. The impact of high and low dose ionising radiation on the central nervous system.

    PubMed

    Betlazar, Calina; Middleton, Ryan J; Banati, Richard B; Liu, Guo-Jun

    2016-10-01

    Responses of the central nervous system (CNS) to stressors and injuries, such as ionising radiation, are modulated by the concomitant responses of the brains innate immune effector cells, microglia. Exposure to high doses of ionising radiation in brain tissue leads to the expression and release of biochemical mediators of 'neuroinflammation', such as pro-inflammatory cytokines and reactive oxygen species (ROS), leading to tissue destruction. Contrastingly, low dose ionising radiation may reduce vulnerability to subsequent exposure of ionising radiation, largely through the stimulation of adaptive responses, such as antioxidant defences. These disparate responses may be reflective of non-linear differential microglial activation at low and high doses, manifesting as an anti-inflammatory or pro-inflammatory functional state. Biomarkers of pathology in the brain, such as the mitochondrial Translocator Protein 18kDa (TSPO), have facilitated in vivo characterisation of microglial activation and 'neuroinflammation' in many pathological states of the CNS, though the exact function of TSPO in these responses remains elusive. Based on the known responsiveness of TSPO expression to a wide range of noxious stimuli, we discuss TSPO as a potential biomarker of radiation-induced effects.

  20. Martian sub-surface ionising radiation: biosignatures and geology

    NASA Astrophysics Data System (ADS)

    Dartnell, L. R.; Desorgher, L.; Ward, J. M.; Coates, A. J.

    2007-02-01

    The surface of Mars, unshielded by thick atmosphere or global magnetic field, is exposed to high levels of cosmic radiation. This ionizing radiation field is deleterious to the survival of dormant cells or spores and the persistence of molecular biomarkers in the subsurface, and so its characterisation is of prime astrobiological interest. Previous research has attempted to address the question of biomarker persistence by inappropriately using dose profiles weighted specifically for cellular survival. Here, we present modelling results of the unmodified physically absorbed radiation dose as a function of depth through the Martian subsurface. A second major implementation of this dose accumulation rate data is in application of the optically stimulated luminescence technique for dating Martian sediments. We present calculations of the dose-depth profile from galactic cosmic rays in the Martian subsurface for various scenarios: variations of surface composition (dry regolith, ice, layered permafrost), solar minimum and maximum conditions, locations of different elevation (Olympus Mons, Hellas basin, datum altitude), and increasing atmospheric thickness over geological history. We also model the changing composition of the subsurface radiation field with depth compared between Martian locations with different shielding material, determine the relative dose contributions from primaries of different energies, and briefly treat particle deflection by the crustal magnetic fields.

  1. For discussion: obtaining consent for ionising radiation: has the time come?

    PubMed

    Mendelson, Richard M

    2010-10-01

    The aim of this paper is to promote debate on the issues surrounding the provision of information to, and the obtaining of valid consent from patients exposed to ionising radiation (IR) from diagnostic and interventional imaging procedures. This is especially pertinent in view of recent interest in the risks of IR expressed in the medical and lay press.

  2. Destruction of Raman biosignatures by ionising radiation and the implications for life detection on Mars.

    PubMed

    Dartnell, Lewis R; Page, Kristian; Jorge-Villar, Susana E; Wright, Gary; Munshi, Tasnim; Scowen, Ian J; Ward, John M; Edwards, Howell G M

    2012-04-01

    Raman spectroscopy has proven to be a very effective approach for the detection of microorganisms colonising hostile environments on Earth. The ExoMars rover, due for launch in 2018, will carry a Raman laser spectrometer to analyse samples of the martian subsurface collected by the probe's 2-m drill in a search for similar biosignatures. The martian surface is unprotected from the flux of cosmic rays, an ionising radiation field that will degrade organic molecules and so diminish and distort the detectable Raman signature of potential martian microbial life. This study employs Raman spectroscopy to analyse samples of two model organisms, the cyanobacterium Synechocystis sp. PCC 6803 and the extremely radiation resistant polyextremophile Deinococcus radiodurans, that have been exposed to increasing doses of ionising radiation. The three most prominent peaks in the Raman spectra are from cellular carotenoids: deinoxanthin in D. radiodurans and β-carotene in Synechocystis. The degradative effect of ionising radiation is clearly seen, with significant diminishment of carotenoid spectral peak heights after 15 kGy and complete erasure of Raman biosignatures by 150 kGy of ionising radiation. The Raman signal of carotenoid in D. radiodurans diminishes more rapidly than that of Synechocystis, believed to be due to deinoxanthin acting as a superior scavenger of radiolytically produced reactive oxygen species, and so being destroyed more quickly than the less efficient antioxidant β-carotene. This study highlights the necessity for further experimental work on the manner and rate of degradation of Raman biosignatures by ionising radiation, as this is of prime importance for the successful detection of microbial life in the martian near subsurface.

  3. Leaf Anatomy and Photochemical Behaviour of Solanum lycopersicum L. Plants from Seeds Irradiated with Low-LET Ionising Radiation

    PubMed Central

    De Micco, V.; Paradiso, R.; Aronne, G.; De Pascale, S.; Quarto, M.; Arena, C.

    2014-01-01

    Plants can be exposed to ionising radiation not only in Space but also on Earth, due to specific technological applications or after nuclear disasters. The response of plants to ionising radiation depends on radiation quality/quantity and/or plant characteristics. In this paper, we analyse some growth traits, leaf anatomy, and ecophysiological features of plants of Solanum lycopersicum L. “Microtom” grown from seeds irradiated with increasing doses of X-rays (0.3, 10, 20, 50, and 100 Gy). Both juvenile and compound leaves from plants developed from irradiated and control seeds were analysed through light and epifluorescence microscopy. Digital image analysis allowed quantifying anatomical parameters to detect the occurrence of signs of structural damage. Fluorescence parameters and total photosynthetic pigment content were analysed to evaluate the functioning of the photosynthetic machinery. Radiation did not affect percentage and rate of seed germination. Plants from irradiated seeds accomplished the crop cycle and showed a more compact habitus. Dose-depended tendencies of variations occurred in phenolic content, while other leaf anatomical parameters did not show distinct trends after irradiation. The sporadic perturbations of leaf structure, observed during the vegetative phase, after high levels of radiation were not so severe as to induce any significant alterations in photosynthetic efficiency. PMID:24883400

  4. EURADOS strategic research agenda: vision for dosimetry of ionising radiation

    PubMed Central

    Rühm, W.; Fantuzzi, E.; Harrison, R.; Schuhmacher, H.; Vanhavere, F.; Alves, J.; Bottollier Depois, J. F.; Fattibene, P.; Knežević, Ž.; Lopez, M. A.; Mayer, S.; Miljanić, S.; Neumaier, S.; Olko, P.; Stadtmann, H.; Tanner, R.; Woda, C.

    2016-01-01

    Since autumn 2012, the European Radiation Dosimetry Group (EURADOS) has been developing its Strategic Research Agenda (SRA), which is intended to contribute to the identification of future research needs in radiation dosimetry in Europe. The present article summarises—based on input from EURADOS Working Groups (WGs) and Voting Members—five visions in dosimetry and defines key issues in dosimetry research that are considered important for the next decades. The five visions include scientific developments required towards (a) updated fundamental dose concepts and quantities, (b) improved radiation risk estimates deduced from epidemiological cohorts, (c) efficient dose assessment for radiological emergencies, (d) integrated personalised dosimetry in medical applications and (e) improved radiation protection of workers and the public. The SRA of EURADOS will be used as a guideline for future activities of the EURADOS WGs. A detailed version of the SRA can be downloaded as a EURADOS report from the EURADOS website (www.eurados.org). PMID:25752758

  5. Xpg limits the expansion of haematopoietic stem and progenitor cells after ionising radiation

    PubMed Central

    Avila, Alush I.; Illing, Anett; Becker, Friedrich; Maerz, Lars D.; Morita, Yohei; Philipp, Melanie; Burkhalter, Martin D.

    2016-01-01

    Reduced capacity of genome maintenance represents a problem for any organism, potentially causing premature death, carcinogenesis, or accelerated ageing. Strikingly though, loss of certain genome stability factors can be beneficial, especially for the maintenance of tissue stem cells of the intestine and the haematopoietic system. We therefore screened for genome stability factors negatively impacting maintenance of haematopoietic stem cells (HSC) in the context of ionising radiation (IR). We found that in vivo knock down of Xeroderma pigmentosum, complementation group G (Xpg) causes elevation of HSC numbers after IR treatment, while numbers of haematopoietic progenitors are elevated to a lesser extent. IR rapidly induces Xpg both on mRNA and on protein level. Prevention of this induction does not influence activation of the checkpoint cascade, yet attenuates late checkpoint steps such as induction of p21 and Noxa. This causes a leaky cell cycle arrest and lower levels of apoptosis, both contributing to increased colony formation and transformation rates. Xpg thus helps to adequately induce DNA damage responses after IR, thereby keeping the expansion of damaged cells under control. This represents a new function of Xpg in the response to IR, in addition to its well-characterized role in nucleotide excision repair. PMID:27137888

  6. Induction of Hsp70 by desiccation, ionising radiation and heat-shock in the eutardigrade Richtersius coronifer.

    PubMed

    Jönsson, K Ingemar; Schill, Ralph O

    2007-04-01

    The physiology and biochemistry behind the extreme tolerance to desiccation shown by the so-called anhydrobiotic animals represents an exciting challenge to biology. The current knowledge suggests that both carbohydrates and proteins are often involved in protecting the dry cell from damage, or in the repair of induced damage. Tardigrades belong to the most desiccation-tolerant multicellular organisms, but very little research has been reported on the biochemistry behind desiccation tolerance in this group. We quantified the induction of the heat-shock protein Hsp70, a very wide-spread stress protein, in response to desiccation, ionising radiation, and heating, in the anhydrobiotic tardigrade Richtersius coronifer using an immuno-westernblot method. Elevated levels of Hsp70 were recorded after treatment of both heat and ionising radiation, and also in rehydrated tardigrades after a period of desiccation. In contrast, tardigrades in the desiccated (dry) state had reduced Hsp70 levels compared to the non-treated control group. Our results suggest that Hsp70 may be involved in the physiological and biochemical system underlying desiccation (and radiation) tolerance in tardigrades, and that its role may be connected to repair processes after desiccation rather than to biochemical stabilization in the dry state.

  7. How do air ions reflect variations in ionising radiation in the lower atmosphere in a boreal forest?

    NASA Astrophysics Data System (ADS)

    Chen, Xuemeng; Kerminen, Veli-Matti; Paatero, Jussi; Paasonen, Pauli; Manninen, Hanna E.; Nieminen, Tuomo; Petäjä, Tuukka; Kulmala, Markku

    2016-11-01

    Most of the ion production in the atmosphere is attributed to ionising radiation. In the lower atmosphere, ionising radiation consists mainly of the decay emissions of radon and its progeny, gamma radiation of the terrestrial origin as well as photons and elementary particles of cosmic radiation. These types of radiation produce ion pairs via the ionisation of nitrogen and oxygen as well as trace species in the atmosphere, the rate of which is defined as the ionising capacity. Larger air ions are produced out of the initial charge carriers by processes such as clustering or attachment to pre-existing aerosol particles. This study aimed (1) to identify the key factors responsible for the variability in ionising radiation and in the observed air ion concentrations, (2) to reveal the linkage between them and (3) to provide an in-depth analysis into the effects of ionising radiation on air ion formation, based on measurement data collected during 2003-2006 from a boreal forest site in southern Finland. In general, gamma radiation dominated the ion production in the lower atmosphere. Variations in the ionising capacity came from mixing layer dynamics, soil type and moisture content, meteorological conditions, long-distance transportation, snow cover attenuation and precipitation. Slightly similar diurnal patterns to variations in the ionising capacity were observed in air ion concentrations of the cluster size (0.8-1.7 nm in mobility diameters). However, features observed in the 0.8-1 nm ion concentration were in good connection to variations of the ionising capacity. Further, by carefully constraining perturbing variables, a strong dependency of the cluster ion concentration on the ionising capacity was identified, proving the functionality of ionising radiation in air ion production in the lower atmosphere. This relationship, however, was only clearly observed on new particle formation (NPF) days, possibly indicating that charges after being born underwent different

  8. Lemna minor plants chronically exposed to ionising radiation: RNA-seq analysis indicates a dose rate dependent shift from acclimation to survival strategies.

    PubMed

    Van Hoeck, Arne; Horemans, Nele; Nauts, Robin; Van Hees, May; Vandenhove, Hildegarde; Blust, Ronny

    2017-04-01

    Ecotoxicological research provides knowledge on ionising radiation-induced responses in different plant species. However, the sparse data currently available are mainly extracted from acute exposure treatments. To provide a better understanding of environmental exposure scenarios, the response to stress in plants must be followed in more natural relevant chronic conditions. We previously showed morphological and biochemical responses in Lemna minor plants continuously exposed for 7days in a dose-rate dependent manner. In this study responses on molecular (gene expression) and physiological (photosynthetic) level are evaluated in L. minor plants exposed to ionising radiation. To enable this, we examined the gene expression profiles of irradiated L. minor plants by using an RNA-seq approach. The gene expression data reveal indications that L. minor plants exposed at lower dose rates, can tolerate the exposure by triggering acclimation responses. In contrast, at the highest dose rate tested, a high number of genes related to antioxidative defense systems, DNA repair and cell cycle were differentially expressed suggesting that only high dose rates of ionising radiation drive L. minor plants into survival strategies. Notably, the photosynthetic process seems to be unaffected in L. minor plants among the tested dose rates. This study, supported by our earlier work, clearly indicates that plants shift from acclimation responses towards survival responses at increasing dose rates of ionising radiation.

  9. On the divergences in assessment of environmental impacts from ionising radiation following the Fukushima accident.

    PubMed

    Strand, P; Sundell-Bergman, S; Brown, J E; Dowdall, M

    2017-04-01

    The accident at the Fukushima-Daiichi Nuclear Power Station on March 11, 2011, led to significant contamination of the surrounding terrestrial and marine environments. Whilst impacts on human health remain the primary concern in the aftermath of such an accident, recent years have seen a significant body of work conducted on the assessment of the accident's impacts on both the terrestrial and marine environment. Such assessments have been undertaken at various levels of biological organisation, for different species, using different methodologies and coming, in many cases, to divergent conclusions as to the effects of the accident on the environment. This article provides an overview of the work conducted in relation to the environmental impacts of the Fukushima accident, critically comparing and contrasting methodologies and results with a view towards finding reasons for discrepancies, should they indeed exist. Based on the outcomes of studies conducted to date, it would appear that in order to avoid the fractured and disparate conclusions drawn in the aftermath of previous accidents, radioactive contaminants and their effects can no longer simply be viewed in isolation with respect to the ecosystems these effects may impact. A combination of laboratory based and field studies with a focus on ecosystem functioning and effects could offer the best opportunities for coherence in the interpretation of the results of studies into the environmental impacts of ionising radiation.

  10. Cytogenetic monitoring of nuclear workers occupationally exposed to ionising radiation.

    PubMed

    Gricienė, B; Slapšytė, G; Mierauskienė, J

    2014-06-01

    Chromosome aberration (CA) analysis using Giemsa techniques was performed in blood lymphocytes of 84 nuclear workers with cumulative doses of 1-632 mSv during employment periods of 1-25 y. The control group comprised 82 healthy male donors. An estimated CA frequency in the total radiation-exposed group was significantly higher when compared with the controls (2.27 vs. 1.76 CA/100 cells, p < 0.05). CA analyses revealed no significant differences between workers with external gamma radiation exposure and the controls (1.60 vs. 1.76 CA/100 cells, p > 0.05). However, significant increase in the total CA frequency was determined in workers with additional internal exposure (2.54 CA/100 cells, p < 0.05) and those with registered neutron doses (2.95 CA/100 cells, p < 0.01). No correlation was found between CA frequency and occupational exposure dose. Borderline significant correlation was found between duration of employment and total CA (r = 0.218, p = 0.046, Fig. 2) and chromosome-type aberration (r = 0.265, p = 0.015) frequency.

  11. EVOLUTION OF THE IEC AND EN STANDARDS FOR INDIVIDUAL MONITORING OF IONISING RADIATION.

    PubMed

    Voytchev, M; Behrens, R; Ambrosi, P; Radev, R; Chiaro, P

    2016-09-01

    This article presents the evolution of the International Electrotechnical Commission (IEC) and the European standards for individual monitoring of ionising radiation issued, respectively, from the committees IEC/Sub Committee 45B and European Committee for Electro-technical Standardization/Technical Committee 45B 'Radiation protection instrumentation'. Standards for passive individual photon and beta dosimetry systems as well as those for active individual monitors are discussed. A neutron ambient dose equivalent (rate) meter standard and a technical report concerning the determination of uncertainty in measurement are also covered.

  12. Non-ionising radiation human exposure assessment near telecommunication devices in Croatia.

    PubMed

    Simunić, Dina

    2006-03-01

    This paper gives an overview of the regulatory acts in non-ionising radiation in the world, with a special emphasis on basic guidelines issued by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). ICNIRP Guidelines are implemented in many countries worldwide. Croatia has also implemented them indirectly through the European Recommendation 1999/519/EC. The Croatian regulatory acts include the Non-lonising Radiation Protection Act, Ordinance on Electromagnetic Fields (EMF) Protection, and the Ordinance on Basic Requirements for Devices which produce Optical Radiation and Measures for Optical Radiation Protection. Dosimetry and densitometry are compliant with relevant international and European standards. The paper presents an example of densitometric human exposure assessment in complex indoor exposure conditions. In spite of a high number of indoor and outdoor sources and the "worst-case exposure assessment", the results are within the limits defined by the Croatian EMF Ordinance.

  13. Exploring Learners' Conceptual Resources: Singapore a Level Students' Explanations in the Topic of Ionisation Energy

    ERIC Educational Resources Information Center

    Taber, Keith S.; Tan, Kim Chwee Daniel

    2007-01-01

    This paper describes findings from a study to explore Singapore A-level (Grades 11 and 12, 16-19 yr old) students' understanding of ionisation energy, an abstract and complex topic that is featured in school chemistry courses. Previous research had reported that students in the United Kingdom commonly use alternative notions based on the perceived…

  14. Radiation in the workplace-a review of studies of the risks of occupational exposure to ionising radiation.

    PubMed

    Wakeford, Richard

    2009-06-01

    Many individuals are, or have been, exposed to ionising radiation in the course of their work and the epidemiological study of occupationally irradiated groups offers an important opportunity to complement the estimates of risks to health resulting from exposure to radiation that are obtained from other populations, such as the Japanese survivors of the atomic bombings of Hiroshima and Nagasaki in 1945. Moreover, workplace exposure to radiation usually involves irradiation conditions that are of direct relevance to the principal concern of radiological protection: protracted exposure to low level radiation. Further, some workers have been exposed to radioactive material that has been inadvertently taken into the body, and the study of these groups leads to risk estimates derived directly from the experience of those irradiated by these 'internal emitters', intakes of alpha-particle-emitters being of particular interest. Workforces that have been the subject of epidemiological study include medical staff, aircrews, radium dial luminisers, underground hard-rock miners, Chernobyl clean-up workers, nuclear weapons test participants and nuclear industry workers. The first solid epidemiological evidence of the stochastic effects of irradiation came from a study of occupational exposure to medical x-rays that was reported in 1944, which demonstrated a large excess risk of leukaemia among US radiologists; but the general lack of dose records for early medical staff who tended to experience the highest exposures hampers the derivation of risks per unit dose received by medical workers. The instrument dial luminisers who inadvertently ingested large amounts of radium-based paint and underground hard-rock miners who inhaled large quantities of radon and its decay products suffered markedly raised excess risks of, respectively, bone and lung cancers; the miner studies have provided standard risk estimates for radon-induced lung cancer. The large numbers of nuclear industry

  15. The effect of non ionising electromagnetic radiation on RAAF personnel during World War II.

    PubMed

    Flaherty, J A

    1994-05-01

    Did exposure to non ionising electromagnetic radiation during World War II in the short term have a stimulating effect on the anterior pituitary gland, and in turn on the gonads of both sexes, since the figures obtained appeared to affect the sexes equally? Is it that the long-term effect of microwave radiation on personnel is to cause adenoma and carcinoma? Is this long-term effect similar to the long-term effect of X-rays on infants, children and adolescents? According to Harrison's Principles of Internal Medicine 1980 (page 1710): "X-rays to the head and neck in infancy, childhood or adolescence is associated with a high incidence of thyroid disease later in life. Nodular disease is found to be particularly common on 20% of patients at risk, and may not be apparent until 30 years or more after exposure. One-third of the nodular type are found to be carcinomatous." The effect of non ionising electromagnetic and microwave radiation on those who work in these fields certainly needs much more investigation. What will be the long-term effect of using micro-ovens on the rising generation?

  16. Glioblastoma stem cells: radiobiological response to ionising radiations of different qualities.

    PubMed

    Pecchia, I; Dini, V; Ricci-Vitiani, L; Biffoni, M; Balduzzi, M; Fratini, E; Belli, M; Campa, A; Esposito, G; Cirrone, G; Romano, F; Stancampiano, C; Pelacchi, F; Pallini, R; Tabocchini, M A

    2015-09-01

    Glioblastoma multiforme (GBM) is the most common and malignant primary brain tumour, with very poor prognosis. The high recurrence rate and failure of conventional treatments are expected to be related to the presence of radio-resistant cancer stem cells (CSCs) inside the tumour mass. CSCs can both self-renew and differentiate into the heterogeneous lineages of cancer cells. Recent evidence showed a higher effectiveness of C-ions and protons in inactivating CSCs, suggesting a potential advantage of Hadrontherapy compared with conventional radiotherapy for GBM treatment. To investigate the mechanisms involved in the molecular and cellular responses of CSCs to ionising radiations, two GBM stem cell (GSC) lines, named lines 1 and 83, which were derived from patients with different clinical outcomes and having different metabolic profiles (as shown by NMR spectroscopy), were irradiated with (137)Cs photons and with protons or C-ions of 62 MeV u(-1) in the dose range of 5-40 Gy. The biological effects investigated were: cell death, cell cycle progression, and DNA damage induction and repair. Preliminary results show a different response to ionising radiation between the two GSC lines for the different end points investigated. Further experiments are in progress to consolidate the data and to get more insights on the influence of radiation quality.

  17. Characterisation of PRESAGE: A new 3-D radiochromic solid polymer dosemeter for ionising radiation.

    PubMed

    Adamovics, J; Maryanski, M J

    2006-01-01

    For the past 50 years there has been interest in developing 3-D dosemeters for ionising radiation. Particular emphasis has been put on those dosemeters that change their optical properties in proportion to the absorbed dose. Many of the dosemeters that have been evaluated have had limitations such as lack of transparency, diffusion of the image of the dose distribution or poor stability of baseline optical density. Many of these performance limitations have been overcome by the development of PRESAGE, an optically clear polyurethane-based radiochromic 3-D dosemeter. The solid PRESAGE dosemeter is formulated with a free radical initiator and a leuco dye and it does not require a container to maintain its shape. The polyurethane matrix is tissue equivalent and prevents the diffusion of the dose distribution image. There is a linear dose-response, which is independent of both photon energy and dose rate. Simple precautions such as preventing long-term exposure to additional ionising radiation including ultraviolet and controlling storage temperatures prevent the bleaching of the radiochromic response field within the irradiated dosemeter.

  18. Effect of ionising radiation treatment on the specific migration characteristics of packaging-food simulant combinations: effect of type and dose of radiation.

    PubMed

    Zygoura, P D; Paleologos, E K; Kontominas, M G

    2011-05-01

    Migration levels of acetyl tributyl citrate (ATBC) plasticiser from polyvinyl chloride (PVC) film into the European Union specified aqueous food simulants (distilled water, 3% w/v acetic acid and 10% v/v ethanol) were monitored as a function of time. Migration testing was carried out at 40°C for 10 days. Determination of the analyte was performed by applying an analytical methodology based on surfactant (Triton X-114) mediated extraction prior to gas chromatographic-flame ionisation detection. PVC cling film used was subjected to ionising treatment with a [(60)Co] source, as well as to electron-beam irradiation at doses equal to 5, 15 and 25 kGy, with the aim to compare the effect of type and dose of radiation on the specific migration behaviour of PVC. Equilibrium concentrations of acetyl tributyl citrate into the aqueous solvents covered the ranges 173-422 µg l(-1) and 296-513 µg l(-1) for gamma- and electron-irradiated PVC, respectively. Hence, e-beam irradiation resulted in significantly higher ATBC migration compared with gamma treatment. The highest extraction efficiency of the 10% ethanol solution was common in both gamma and e-beam treatments; distilled water demonstrated the lowest migration. Gamma-irradiation at intermediate doses up to 5 kGy produced no statistically significant (p > 0.05) effect on ATBC migration into all three aqueous simulants; however, this does not apply for high-energy electrons. Both ionising treatments were similar in that they resulted in statistically significant (p < 0.05) differences in plasticiser migrating amounts between non-irradiated and irradiated at doses of 15 and 25 kGy samples. Gamma-radiation did not affect the kinetics of plasticiser migration. On the contrary, electron-beam radiation produced shorter equilibration times for all food-simulating solvents tested at 40°C. The above values regarding ATBC migration into aqueous food simulants are far below the European Union restriction (1 mg kg(-1) body weight

  19. Ionising radiation exposure in patients with circular frame treatment of distal tibial fractures.

    PubMed

    Bryant, H; Dearden, P M C; Harwood, P J; Wood, T J; Sharma, H K

    2015-08-01

    Total radiation exposure accumulated during circular frame treatment of distal tibial fractures was quantified in 47 patients treated by a single surgeon from February 2007 until Oct 2010. The radiation exposures for all relevant radiology procedures for the distal tibial injury were included to estimate the radiation risk to the patient. The median time of treatment in the frame was 169 days (range 105-368 days). Patients underwent a median of 13 sets of plain radiographs; at least one intra operative exposure and 16 patients underwent CT scanning. The median total effective dose per patient from time of injury to discharge was 0.025mSv (interquartile range 0.013-0.162 and minimum to maximum 0.01-0.53). The only variable shown to be an independent predictor of cumulative radiation dose on multivariate analysis was the use of CT scanning. This was associated with a 13-fold increase in overall exposure. Radiation exposure during treatment of distal tibial fractures with a circular frame in this group was well within accepted safe limits. The fact that use of CT was the only significant predictor of overall exposure serves as a reminder to individually assess the risk and utility of radiological investigations on an individual basis. This is consistent with the UK legal requirements for justification of all X-ray imaging, as set out in the Ionising Radiation (Medical Exposure) Regulations 2000 [1].

  20. Chronic low-dose-rate ionising radiation affects the hippocampal phosphoproteome in the ApoE−/− Alzheimer's mouse model

    PubMed Central

    Kempf, Stefan J.; Janik, Dirk; Barjaktarovic, Zarko; Braga-Tanaka, Ignacia; Tanaka, Satoshi; Neff, Frauke; Saran, Anna; Larsen, Martin R.; Tapio, Soile

    2016-01-01

    Accruing data indicate that radiation-induced consequences resemble pathologies of neurodegenerative diseases such as Alzheimer's. The aim of this study was to elucidate the effect on hippocampus of chronic low-dose-rate radiation exposure (1 mGy/day or 20 mGy/day) given over 300 days with cumulative doses of 0.3 Gy and 6.0 Gy, respectively. ApoE deficient mutant C57Bl/6 mouse was used as an Alzheimer's model. Using mass spectrometry, a marked alteration in the phosphoproteome was found at both dose rates. The radiation-induced changes in the phosphoproteome were associated with the control of synaptic plasticity, calcium-dependent signalling and brain metabolism. An inhibition of CREB signalling was found at both dose rates whereas Rac1-Cofilin signalling was found activated only at the lower dose rate. Similarly, the reduction in the number of activated microglia in the molecular layer of hippocampus that paralleled with reduced levels of TNFα expression and lipid peroxidation was significant only at the lower dose rate. Adult neurogenesis, investigated by Ki67, GFAP and NeuN staining, and cell death (activated caspase-3) were not influenced at any dose or dose rate. This study shows that several molecular targets induced by chronic low-dose-rate radiation overlap with those of Alzheimer's pathology. It may suggest that ionising radiation functions as a contributing risk factor to this neurodegenerative disease. PMID:27708245

  1. Multicolour FISH analysis of ionising radiation induced micronucleus formation in human lymphocytes

    PubMed Central

    Balajee, Adayabalam S.; Bertucci, Antonella; Taveras, Maria; Brenner, David J.

    2014-01-01

    Micronucleation of chromosomal DNA is an effective indicator of DNA damage and micronucleus (MN) analysis is a valuable tool for radiation biodosimetry studies. To gain a comprehensive knowledge of micronucleation process after ionising radiation (IR) exposure, whole genome-wide chromosome analysis is desirable. With this objective, multicolour fluorescence in situ hybridization (M-FISH) technique was utilised in the present study to characterise the chromosome content of spontaneous and IR-induced micronuclei in three human donors. M-FISH analysis revealed a radiation dose-dependant increase in the number of micronuclei with multi-chromosome material above 2 Gy and as many as 3–6 multicolour signals were detected in micronuclei after high γ-rays radiation doses (5–10 Gy). Involvement of each human chromosome material was more frequently detected in multicoloured micronuclei than in single-coloured micronuclei at high radiation doses (>2 Gy). Observation of dose-dependant increase in the MN frequency with multi-chromosome material may be due to misrepair of DNA double-strand breaks involving multiple chromosomes leading to asymmetric dicentric or ring chromosomes and acentric fragments. Chromosomes belonging to groups A (1, 2 and 3) and B (4 and 5) were frequently detected in 35–45% of the total micronuclei either as single entities or in combination with other chromosomes. Among the A and B groups, chromosome 1 material was consistently detected at high MN frequencies after radiation exposure in all the donors. Additionally, chromosomes 13 and 19 were more frequently observed in micronuclei than the expected frequency based on DNA content. Our whole genome approach utilising the M-FISH technique revealed that MN formation at high radiation doses might be complex involving multiple chromosome fragments. Understanding the fate and biological consequences of these multi-chromosome-containing micronuclei may provide key molecular insights for some aspects of IR

  2. Low-dose ionising radiation and cardiovascular diseases--Strategies for molecular epidemiological studies in Europe.

    PubMed

    Kreuzer, Michaela; Auvinen, Anssi; Cardis, Elisabeth; Hall, Janet; Jourdain, Jean-Rene; Laurier, Dominique; Little, Mark P; Peters, Annette; Raj, Ken; Russell, Nicola S; Tapio, Soile; Zhang, Wei; Gomolka, Maria

    2015-01-01

    It is well established that high-dose ionising radiation causes cardiovascular diseases. In contrast, the evidence for a causal relationship between long-term risk of cardiovascular diseases after moderate doses (0.5-5 Gy) is suggestive and weak after low doses (<0.5 Gy). However, evidence is emerging that doses under 0.5 Gy may also increase long-term risk of cardiovascular disease. This would have major implications for radiation protection with respect to medical use of radiation for diagnostic purposes and occupational or environmental radiation exposure. Therefore, it is of great importance to gain information about the presence and possible magnitude of radiation-related cardiovascular disease risk at doses of less than 0.5 Gy. The biological mechanisms implicated in any such effects are unclear and results from epidemiological studies are inconsistent. Molecular epidemiological studies can improve the understanding of the pathogenesis and the risk estimation of radiation-induced circulatory disease at low doses. Within the European DoReMi (Low Dose Research towards Multidisciplinary Integration) project, strategies to conduct molecular epidemiological studies in this field have been developed and evaluated. Key potentially useful European cohorts are the Mayak workers, other nuclear workers, uranium miners, Chernobyl liquidators, the Techa river residents and several diagnostic or low-dose radiotherapy patient cohorts. Criteria for informative studies are given and biomarkers to be investigated suggested. A close collaboration between epidemiology, biology and dosimetry is recommended, not only among experts in the radiation field, but also those in cardiovascular diseases.

  3. Effect of penetrating ionising radiation on the mechanical properties of pericardium

    NASA Astrophysics Data System (ADS)

    Daar, Eman; Woods, E.; Keddie, J. L.; Nisbet, A.; Bradley, D. A.

    2010-07-01

    The pericardium is an anistropic composite material made up of collagen and elastin fibres embedded in an amorphous matrix mainly composed of proteoglycan and hyaluronan. The collagen fibres are arranged in layers, with different directions of alignment in each layer, giving rise to interesting mechanical properties of pericardium, including the ability to undergo large deformation during performance of regular physiological functions. The present study aims to investigate the effect of penetrating photon ionising radiation on bovine pericardium tissue, being part of a study of the effect of cardiac doses received in breast radiotherapy and the possibility that this can give rise to cardiovascular complications. Irradiation doses in the range 5-80 Gy were used. To characterise the various mechanical properties [elastic modulus, stress relaxation, ultimate tensile strength (UTS) and fracture] a uniaxial tensile test method was applied. The preliminary results reflect the wide inter-sample variations that are expected in dealing with tissues, with only a weak indication of increase in the UTS of the pericardium tissue with increase in radiation dose. Such an effect has also been observed by others, with reduction in UTS at doses of 80 Gy.

  4. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Evolution of tubular singular pulsed beams in a nonlinear dielectric medium upon ionisation

    NASA Astrophysics Data System (ADS)

    Vlasov, R. A.; Khasanov, O. Kh; Smirnova, T. V.

    2005-10-01

    The dynamics of a high-power femtosecond tubular pulsed beam in a dielectric medium is numerically analysed upon optically induced ionisation. It is found that the balance between nonlinearities of opposite sign and different magnitude in the case of multiphoton ionisation favours the establishment of a quasi-soliton regime of radiation propagation over a distance exceeding several diffraction lengths. The use of these beams enables attaining high-density light fields and generate high-density plasmas.

  5. Expression of the progenitor marker NG2/CSPG4 predicts poor survival and resistance to ionising radiation in glioblastoma.

    PubMed

    Svendsen, Agnete; Verhoeff, Joost J C; Immervoll, Heike; Brøgger, Jan C; Kmiecik, Justyna; Poli, Aurelie; Netland, Inger A; Prestegarden, Lars; Planagumà, Jesús; Torsvik, Anja; Kjersem, Anneli Bohne; Sakariassen, Per Ø; Heggdal, Jan I; Van Furth, Wouter R; Bjerkvig, Rolf; Lund-Johansen, Morten; Enger, Per Ø; Felsberg, Joerg; Brons, Nicolaas H C; Tronstad, Karl J; Waha, Andreas; Chekenya, Martha

    2011-10-01

    Glioblastoma (GBM) is a highly aggressive brain tumour, where patients respond poorly to radiotherapy and exhibit dismal survival outcomes. The mechanisms of radioresistance are not completely understood. However, cancer cells with an immature stem-like phenotype are hypothesised to play a role in radioresistance. Since the progenitor marker neuron-glial-2 (NG2) has been shown to regulate several aspects of GBM progression in experimental systems, we hypothesised that its expression would influence the survival of GBM patients. Quantification of NG2 expression in 74 GBM biopsies from newly diagnosed and untreated patients revealed that 50% express high NG2 levels on tumour cells and associated vessels, being associated with significantly shorter survival. This effect was independent of age at diagnosis, treatment received and hypermethylation of the O(6)-methylguanine methyltransferase (MGMT) DNA repair gene promoter. NG2 was frequently co-expressed with nestin and vimentin but rarely with CD133 and the NG2 positive tumour cells harboured genetic aberrations typical for GBM. 2D proteomics of 11 randomly selected biopsies revealed upregulation of an antioxidant, peroxiredoxin-1 (PRDX-1), in the shortest surviving patients. Expression of PRDX-1 was associated with significantly reduced products of oxidative stress. Furthermore, NG2 expressing GBM cells showed resistance to ionising radiation (IR), rapidly recognised DNA damage and effectuated cell cycle checkpoint signalling. PRDX-1 knockdown transiently slowed tumour growth rates and sensitised them to IR in vivo. Our data establish NG2 as an important prognostic factor for GBM patient survival, by mediating resistance to radiotherapy through induction of ROS scavenging enzymes and preferential DNA damage signalling.

  6. Microsatellite analysis for determination of the mutagenicity of extremely low-frequency electromagnetic fields and ionising radiation in vitro.

    PubMed

    Mairs, Robert J; Hughes, Kate; Fitzsimmons, Sara; Prise, Kevin M; Livingstone, Anne; Wilson, Lesley; Baig, Nazia; Clark, Anne Marie; Timpson, Alan; Patel, Gaurang; Folkard, M; Angerson, Wilson J; Boyd, Marie

    2007-01-10

    Extremely low-frequency electromagnetic fields (ELF-EMF) have been reported to induce lesions in DNA and to enhance the mutagenicity of ionising radiation. However, the significance of these findings is uncertain because the determination of the carcinogenic potential of EMFs has largely been based on investigations of large chromosomal aberrations. Using a more sensitive method of detecting DNA damage involving microsatellite sequences, we observed that exposure of UVW human glioma cells to ELF-EMF alone at a field strength of 1 mT (50 Hz) for 12 h gave rise to 0.011 mutations/locus/cell. This was equivalent to a 3.75-fold increase in mutation induction compared with unexposed controls. Furthermore, ELF-EMF increased the mutagenic capacity of 0.3 and 3 Gy gamma-irradiation by factors of 2.6 and 2.75, respectively. These results suggest not only that ELF-EMF is mutagenic as a single agent but also that it can potentiate the mutagenicity of ionising radiation. Treatment with 0.3 Gy induced more than 10 times more mutations per unit dose than irradiation with 3 Gy, indicating hypermutability at low dose.

  7. Inter-comparison of safety culture within selected practices in Ghana utilising ionising radiation.

    PubMed

    Faanu, A; Schandorf, C; Darko, E O; Boadu, M; Emi-Reynolds, G; Awudu, A R; Gyekye, P K; Kpeglo, D O

    2010-12-01

    The safety culture of selected practices and facilities in Ghana utilising radiation sources or radiation emitting devices has been assessed using a performance indicator, which provided status information on management and operating staff commitment to safety. The questionnaire was based on the following broad areas: general safety considerations, safety policy at the facility level, safety practices at the facility level, definition of responsibility, staff training, safety of the physical structure of the facility and the emergency plans. The analysis showed that the percentage levels of commitment to safety for the respective practices are as follows: conventional radiography, 23.3-90.0%; research reactor, 73.3%; gamma irradiation facility, 53.3%; radiotherapy, 76.7%; X-ray scanner, 80.0%; gamma scanner, 76.7%; industrial radiography 86.7% and nuclear density practice, 78%. None of the practices or facilities was able to satisfy all the requirements that will ensure a 100% level of safety culture.

  8. Implications for human and environmental health of low doses of ionising radiation.

    PubMed

    Mothersill, Carmel; Seymour, Colin

    2014-07-01

    The last 20 years have seen a major paradigm shift in radiation biology. Several discoveries challenge the DNA centric view which holds that DNA damage is the critical effect of radiation irrespective of dose. This theory leads to the assumption that dose and effect are simply linked - the more energy deposition, the more DNA damage and the greater the biological effect. This is embodied in radiation protection (RP) regulations as the linear-non-threshold (LNT) model. However the science underlying the LNT model is being challenged particularly in relation to the environment because it is now clear that at low doses of concern in RP, cells, tissues and organisms respond to radiation by inducing responses which are not readily predictable by dose. These include adaptive responses, bystander effects, genomic instability and low dose hypersensitivity, and are commonly described as stress responses, while recognizing that "stress" can be good as well as bad. The phenomena contribute to observed radiation responses and appear to be influenced by genetic, epigenetic and environmental factors, meaning that dose and response are not simply related. The question is whether our discovery of these phenomena means that we need to re-evaluate RP approaches. The so-called "non-targeted" mechanisms mean that low dose radiobiology is very complex and supra linear or sub-linear (even hormetic) responses are possible but their occurrence is unpredictable for any given system level. Issues which may need consideration are synergistic or antagonistic effects of other pollutants. RP, at present, only looks at radiation dose but the new (NTE) radiobiology means that chemical or physical agents, which interfere with tissue responses to low doses of radiation, could critically modulate the predicted risk. Similarly, the "health" of the organism could determine the effect of a given low dose by enabling or disabling a critical response. These issues will be discussed.

  9. The annual effective dose from natural sources of ionising radiation in Canada.

    PubMed

    Grasty, R L; LaMarre, J R

    2004-01-01

    A review and analysis of published information combined with the results of recent gamma ray surveys were used to determine the annual effective dose to Canadians from natural sources of radiation. The dose due to external radiation was determined from ground gamma ray surveys carried out in the cities of Toronto, Ottawa, Montreal and Winnipeg and was calculated to be 219 microSv. A compilation of airborne gamma ray data from Canada and the United States shows that there are large variations in external radiation with the highest annual outdoor level of 1424 microSv being found in northern Canada. The annual effective inhalation dose of 926 microSv from 222Rn and 220Rn was calculated from approximately 14,000 measurements across Canada. This value includes a contribution of 128 microSv from 222Rn in the outdoor air together with 6 microSv from long-lived uranium and thorium series radionuclides in dust particles. Based on published information, the annual effective dose due to internal radioactivity is 306 microSv. A program developed by the Federal Aviation Administration was used to calculate a population-weighted annual effective dose from cosmic radiation of 318 microSv. The total population-weighted average annual effective dose to Canadians from all sources of natural background radiation was calculated to be 1769 microSv but varies significantly from city to city, largely due to differences in the inhalation dose from 222Rn.

  10. Thermoluminescent properties of Ni and Co doped synthetic, high pressure, high temperature diamonds: application to ionising radiation dosimetry.

    PubMed

    Benabdesselam, M; Iacconi, P; Gheeraert, E; Kanda, H; Lapraz, D; Briand, D

    2002-01-01

    An investigation of the thermoluminescence (TL) properties of high pressure, high temperature (HPHT) synthetic diamond crystals grown under diluted nickel or cobalt as solvent catalysts is reported. After a study of TL properties of 6 different samples, it is shown that a crystal grown with Ni+2%Ti and annealed at 2100 K presents an intense glow peak at around 490 K. This peak is characterised by a broad emission band centred at 530 nm (2.34 eV). This crystal presents a significant, reproducible and linear TL response relative to the absorbed dose up to an X ray air kerma of 10 Gy. All these features make this material suitable for ionising radiation dosimetry. A similar study is made on another crystal grown from pure Co, and a comparative review of the results does show that for dosimetry work, Ni-containing diamonds are more appropriate than those grown from Co catalyst.

  11. Protection of the environment from ionising radiation in a regulatory context (protect): proposed numerical benchmark values.

    PubMed

    Andersson, Pål; Garnier-Laplace, Jacqueline; Beresford, Nicholas A; Copplestone, David; Howard, Brenda J; Howe, Paul; Oughton, Deborah; Whitehouse, Paul

    2009-12-01

    Criteria are needed to be able to judge the level of risk associated with dose rates estimated for non-human biota. In this paper, European guidance on the derivation of predicted no-effect chemical concentrations has been applied to appropriate radiation sensitivity data. A species sensitivity distribution fitted to the data for all species resulted in a generic predicted no-effect dose rate of 10 microGy h(-1).Currently, data are inadequate to derive screening values for separate organism groups. A second, higher, benchmark could aid in decision making by putting results into context on the scale of no effect to a risk of 'serious' effect. The need for, meaning and use of such a value needs to be debated by the wider community. This paper explores potential approaches of deriving scientific input to this debate. The concepts proposed in this paper are broadly consistent with the framework for human protection.

  12. Pre-service Teachers' Subject Knowledge of and Attitudes about Radioactivity and Ionising Radiation

    NASA Astrophysics Data System (ADS)

    Denys Colclough, Nicholas; Lock, Roger; Soares, Allan

    2011-02-01

    This study focussed on secondary school (11-18 years) pre-service teachers' (n = 73) knowledge of and attitudes towards risks associated with alpha, beta, and gamma radiations. A multi-method approach was used with physics, chemistry, biology, and history graduates undertaking the one-year initial teacher training, Post Graduate Certificate in Education course at a university in central England. A novel research tool, involving interviews about real concrete contexts and first-hand data collection with radioactive sources, was employed to gain insights into a sub-set of the sample (n = 12) of pre-service teachers' subject knowledge of and attitudes towards risk. The subject knowledge of all the pre-service teachers was also measured using a Certainty of Response Index instrument; multiple-choice questions with associated confidence indicators. Although the physicists displayed the higher levels of knowledge, they also demonstrated limitations in their knowledge and held misconceptions such as irradiation being confused with contamination. Physics graduates hold more rational attitudes and a greater willingness to accept risk while the attitudes of graduates in the other subject disciplines are more disparate. These findings raise questions about the extent to which pre-service science and history teachers have the knowledge necessary to teach this topic. The article concludes with discussion of the implications these findings have for initial teacher training, continuing professional development needs for teachers already in the profession, and curriculum developers.

  13. Cell culture conditions potentiate differences in the response to ionising radiation of peripheral blood leukocytes isolated from breast cancer patients and healthy subjects.

    PubMed

    Adzić, Miroslav; Nićiforović, Ana; Zarić, Bozidarka; Nesković-Konstantinović, Zora; Spasić, Snezana D; Jones, David R; Radojcić, Marija B

    2008-01-01

    To compare the effects of ionising radiation on leukocytes from breast cancer patients and healthy subjects ex vivo, the level of NF-kappaB and the antioxidant enzymes manganese-containing superoxide dismutase (Mn-SOD), copper/zinc-containing superoxide dismutase (CuZn-SOD) and catalase (CAT) in combination with flow cytometric analysis of CD4+ lymphocytes was performed. The level of Mn-SOD protein was significantly increased in the breast cancer study group both before (P < 0.001) and after (P < 0.001) irradiation when compared with healthy subjects. Measurements in parallel indicated that the level of CAT protein was significantly higher in the breast cancer study group after irradiation (2 Gy [P < 0.001] and 9 Gy [P < 0.05]) when compared with healthy subjects. Although the initial number of lymphocytes in the blood of breast cancer patients was not different from healthy subjects, the percentage of apoptotic CD4+ cells was significantly (P < 0.001) lower both before and after irradiation indicating that cell culture conditions induced radioresistance of CD4+ cells in the blood of breast cancer patients. The data presented in this current study indicate that brief ex vivo culture of peripheral blood leukocytes potentiates oxidative stress imposed by a breast cancer tumour.

  14. Effect of ionising radiation on polyphenolic content and antioxidant potential of parathion-treated sage (Salvia officinalis) leaves.

    PubMed

    Ben Salem, Issam; Fekih, Sana; Sghaier, Haitham; Bousselmi, Mehrez; Saidi, Mouldi; Landoulsi, Ahmed; Fattouch, Sami

    2013-11-15

    The γ-irradiation effects on polyphenolic content and antioxidant capacity of parathion-pretreated leaves of Salvia officinalis plant were investigated. The analysis of phenolic extracts of sage without parathion showed that irradiation decreased polyphenolic content significantly (p<0.05) by 30% and 45% at 2 and 4kGy, respectively, compared to non-irradiated samples. The same trend was observed for the Trolox equivalent antioxidant capacity (TEAC), as assessed by the anionic DPPH and cationic ABTS radical-scavenging assays. The antioxidant potential decreased significantly (p<0.01) at 2 and 4kGy, by 11-20% and 40-44%, respectively. The results obtained with a pure chlorogenic acid solution confirmed the degradation of phenols; however, its TEAC was significantly (p<0.01) increased following irradiation. Degradation products of parathion formed by irradiation seem to protect against a decline of antioxidant capacity and reduce polyphenolic loss. Ionising radiation was found to be useful in breaking down pesticide residues without inducing significant losses in polyphenols.

  15. Pre-Service Teachers' Subject Knowledge of and Attitudes about Radioactivity and Ionising Radiation

    ERIC Educational Resources Information Center

    Colclough, Nicholas Denys; Lock, Roger; Soares, Allan

    2011-01-01

    This study focussed on secondary school (11-18 years) pre-service teachers' (n = 73) knowledge of and attitudes towards risks associated with alpha, beta, and gamma radiations. A multi-method approach was used with physics, chemistry, biology, and history graduates undertaking the one-year initial teacher training, Post Graduate Certificate in…

  16. Uncertainties in estimating health risks associated with exposure to ionising radiation.

    PubMed

    Preston, R Julian; Boice, John D; Brill, A Bertrand; Chakraborty, Ranajit; Conolly, Rory; Hoffman, F Owen; Hornung, Richard W; Kocher, David C; Land, Charles E; Shore, Roy E; Woloschak, Gayle E

    2013-09-01

    The information for the present discussion on the uncertainties associated with estimation of radiation risks and probability of disease causation was assembled for the recently published NCRP Report No. 171 on this topic. This memorandum provides a timely overview of the topic, given that quantitative uncertainty analysis is the state of the art in health risk assessment and given its potential importance to developments in radiation protection. Over the past decade the increasing volume of epidemiology data and the supporting radiobiology findings have aided in the reduction of uncertainty in the risk estimates derived. However, it is equally apparent that there remain significant uncertainties related to dose assessment, low dose and low dose-rate extrapolation approaches (e.g. the selection of an appropriate dose and dose-rate effectiveness factor), the biological effectiveness where considerations of the health effects of high-LET and lower-energy low-LET radiations are required and the transfer of risks from a population for which health effects data are available to one for which such data are not available. The impact of radiation on human health has focused in recent years on cancer, although there has been a decided increase in the data for noncancer effects together with more reliable estimates of the risk following radiation exposure, even at relatively low doses (notably for cataracts and cardiovascular disease). New approaches for the estimation of hereditary risk have been developed with the use of human data whenever feasible, although the current estimates of heritable radiation effects still are based on mouse data because of an absence of effects in human studies. Uncertainties associated with estimation of these different types of health effects are discussed in a qualitative and semi-quantitative manner as appropriate. The way forward would seem to require additional epidemiological studies, especially studies of low dose and low dose

  17. Follow-up of children exposed to ionising radiation from cardiac catheterisation: the Coccinelle study

    PubMed Central

    Baysson, H.; Nkoumazok, B.; Barnaoui, S.; Réhel, J. L.; Girodon, B.; Milani, G.; Boudjemline, Y.; Bonnet, D.; Laurier, D.; Bernier, M. O.

    2015-01-01

    Cardiac catheterisation has become an essential tool in the diagnosis and treatment of children with a wide variety of congenital and acquired forms of cardiovascular disease. Despite the clear clinical benefit to the patient, radiation exposure from paediatric cardiac catheterisation procedures (CCPs) may be substantial. Given children's greater sensitivity to radiation and the longer life span during which radiation health effects can develop, an epidemiological cohort study, named Coccinelle or ‘Ladybird’ (French acronym for ‘Cohorte sur le risque de cancer après cardiologie interventionnelle pédiatrique’), is carried out in France to evaluate the risks of leukaemia and solid cancers in this population. A total number of 8000 included children are expected. Individual CCP-related doses will be assessed for each child included in the cohort. For each CCP performed, dosimetric parameters (dose–area product, fluoroscopy time and total number of cine frames) are retrieved retrospectively. Organ doses, especially to the lung, the oesophagus and the thyroid, are calculated with PCXMC software. The cohort will be followed up through linkage with French paediatric cancer registries. PMID:25833897

  18. Genotoxicity Induced by Foetal and Infant Exposure to Magnetic Fields and Modulation of Ionising Radiation Effects

    PubMed Central

    Udroiu, Ion; Antoccia, Antonio; Tanzarella, Caterina; Giuliani, Livio; Pacchierotti, Francesca; Cordelli, Eugenia; Eleuteri, Patrizia; Villani, Paola; Sgura, Antonella

    2015-01-01

    Background Few studies have investigated the toxicity and genotoxicity of extremely low frequency magnetic fields (ELF-MF) during prenatal and neonatal development. These phases of life are characterized by cell proliferation and differentiation, which might make them sensitive to environmental stressors. Although in vitro evidences suggest that ELF-MF may modify the effects of ionizing radiation, no research has been conducted so far in vivo on the genotoxic effects of ELF-MF combined with X-rays. Aim and methods Aim of this study was to investigate in somatic and germ cells the effects of chronic ELF-MF exposure from mid gestation until weaning, and any possible modulation produced by ELF-MF exposure on ionizing radiation-induced damage. Mice were exposed to 50 Hz, 65 μT magnetic field, 24 hours/day, for a total of 30 days, starting from 12 days post-conception. Another group was irradiated with 1 Gy X-rays immediately before ELF-MF exposure, other groups were only X-irradiated or sham-exposed. Micronucleus test on blood erythrocytes was performed at multiple times from 1 to 140 days after birth. Additionally, 42 days after birth, genotoxic and cytotoxic effects on male germ cells were assessed by comet assay and flow cytometric analysis. Results ELF-MF exposure had no teratogenic effect and did not affect survival, growth and development. The micronucleus test indicated that ELF-MF induced a slight genotoxic damage only after the maximum exposure time and that this effect faded away in the months following the end of exposure. ELF-MF had no effects on ionizing radiation (IR)-induced genotoxicity in erythrocytes. Differently, ELF–MF appeared to modulate the response of male germ cells to X-rays with an impact on proliferation/differentiation processes. These results point to the importance of tissue specificity and development on the impact of ELF-MF on the early stages of life and indicate the need of further research on the molecular mechanisms underlying

  19. Determination of methemoglobin in human blood after ionising radiation by EPR

    NASA Astrophysics Data System (ADS)

    Polakovs, M.; Mironova-Ulmane, N.; Pavlenko, A.; Aboltins, A.

    2015-03-01

    In the present work presents results of investigations of radiation influence on blood of patients examined by radio-isotopes diagnosis (Tc99m), blood of Chernobyl clean-up workers and human blood irradiated by LINAC using Electron Paramagnetic Resonance (EPR). The EPR spectroscopy reveals information on electronic states of transition metal ions, particularly Fe3+ in different spin states. It is shown that EPR spectra of blood of patients before examination has signal from metal-protein transferrin (g=4.3) and after administration of radioisotope proves signal of Fe3+ (methemaglobin) in the high spin state (g=6.0). The EPR spectra of Chernobyl liquidator display number of signals including low and high state of ion Fe3+ (g = 2.0 and g=6.0), and transferrin (g=4.3). The EPR spectra of irradiated human blood by LINAC (linear accelerator) have only signal Fe3+ (methemaglobin) in low-spin state with g = 2.0.

  20. Chromosome instability of HPRT-mutant subclones induced by ionising radiation of various let

    NASA Astrophysics Data System (ADS)

    Govorun, R. D.; Koshlan, I. V.; Koshlan, N. A.; Krasavin, E. A.; Shmakova, N. L.

    The induction of HPRT-mutations and survival of Chinese hamster cells (line B11ii-FAF28, clone 431) were studied after irradiation by 4He and 12C-ions of various LET (20 - 360 keV/μm), produced by the U-200 heavy ion accelerator. The RBE increases with LET up to the maximum at 100-200 keV/μm and then decreases. Cytogenetic analysis was performed on the HPRT-mutant subclones selected from unirradiated Chinese hamster V-79 cells and from HPRT- mutant subclones that arose after exposure to γ-rays, 1GeV protons and 14N-ions (LET - 77 keV/μm), produced by the synchrophasotron and the U-400M heavy ion accelerator. Slow growing mutant subclones were observed. The cytogenetic properties of individual clones were highly heterogeneous and chromosome instability was observed in both spontaneous and radiation-induced mutants. Chromosome instability was highest among spontaneous mutants and decreased with increasing LET.

  1. Chromosome instability of HPRT-mutant subclones induced by ionising radiation of various LET.

    PubMed

    Govorun, R D; Koshlan, I V; Koshlan, N A; Krasavin, E A; Shmakova, N L

    2002-01-01

    The induction of HPRT-mutations and survival of Chinese hamster cells (line B11ii-FAF28, clone 431) were studied after irradiation by 4He and 12C-ions of various LET (20-360 keV/micrometers), produced by the U-200 heavy ion accelerator. The RBE increases with LET up to the maximum at 100-200 keV/micrometers and then decreases. Cytogenetic analysis was performed on the HPRT-mutant subclones selected from unirradiated Chinese hamster V-79 cells and from HPRT-mutant subclones that arose after exposure to gamma-rays, 1 GeV protons and 14N-ions (LET-77 keV/micrometers), produced by the synchrophasotron and the U-400M heavy ion accelerator. Slow growing mutant subclones were observed. The cytogenetic properties of individual clones were highly heterogeneous and chromosome instability was observed in both spontaneous and radiation-induced mutants. Chromosome instability was highest among spontaneous mutants and decreased with increasing LET.

  2. Ionising radiation and risk of death from leukaemia and lymphoma in radiation-monitored workers (INWORKS): an international cohort study

    PubMed Central

    Leuraud, Klervi; Richardson, David B; Cardis, Elisabeth; Daniels, Robert D; Gillies, Michael; O'Hagan, Jacqueline A; Hamra, Ghassan B; Haylock, Richard; Laurier, Dominique; Moissonnier, Monika; Schubauer-Berigan, Mary K; Thierry-Chef, Isabelle; Kesminiene, Ausrele

    2015-01-01

    Summary Background There is much uncertainty about the risks of leukaemia and lymphoma after repeated or protracted low-dose radiation exposure typical of occupational, environmental, and diagnostic medical settings. We quantified associations between protracted low-dose radiation exposures and leukaemia, lymphoma, and multiple myeloma mortality among radiation-monitored adults employed in France, the UK, and the USA. Methods We assembled a cohort of 308 297 radiation-monitored workers employed for at least 1 year by the Atomic Energy Commission, AREVA Nuclear Cycle, or the National Electricity Company in France, the Departments of Energy and Defence in the USA, and nuclear industry employers included in the National Registry for Radiation Workers in the UK. The cohort was followed up for a total of 8·22 million person-years. We ascertained deaths caused by leukaemia, lymphoma, and multiple myeloma. We used Poisson regression to quantify associations between estimated red bone marrow absorbed dose and leukaemia and lymphoma mortality. Findings Doses were accrued at very low rates (mean 1·1 mGy per year, SD 2·6). The excess relative risk of leukaemia mortality (excluding chronic lymphocytic leukaemia) was 2·96 per Gy (90% CI 1·17–5·21; lagged 2 years), most notably because of an association between radiation dose and mortality from chronic myeloid leukaemia (excess relative risk per Gy 10·45, 90% CI 4·48–19·65). Interpretation This study provides strong evidence of positive associations between protracted low-dose radiation exposure and leukaemia. Funding Centers for Disease Control and Prevention, Ministry of Health, Labour and Welfare of Japan, Institut de Radioprotection et de Sûreté Nucléaire, AREVA, Electricité de France, National Institute for Occupational Safety and Health, US Department of Energy, US Department of Health and Human Services, University of North Carolina, Public Health England. PMID:26436129

  3. On the mechanism of populating 3p levels of neon under pumping by a hard ioniser

    SciTech Connect

    Khasenov, M U

    2011-03-31

    The effect of quenching additives on the luminescence properties of helium - neon mixtures under pumping by {alpha} particles emitted from {sup 210}Po atoms is considered. It is concluded that, under excitation by a heavy charged particle, the population of the 3p'[1/2]{sub 0} level of neon is not related to the dissociative recombination of molecular ions. It is suggested that the most likely channels for populating the 3p level are the excitation transfer from metastable helium atoms to neon atoms and direct excitation of neon by nuclear particles and secondary electrons. (lasers and active media)

  4. Selective laser ionisation of radionuclide 63Ni

    NASA Astrophysics Data System (ADS)

    Tsvetkov, G. O.; D’yachkov, A. B.; Gorkunov, A. A.; Labozin, A. V.; Mironov, S. M.; Firsov, V. A.; Panchenko, V. Ya.

    2017-02-01

    We report a search for a scheme of selective laser stepwise ionisation of radionuclide 63Ni by radiation of a dye laser pumped by a copper vapour laser. A three-stage scheme is found with ionisation through an autoionising state (AIS): 3d 84s2 3F4(E = 0) → 3d 94p 1Fo3(31030.99 cm‑1) → 3d 94d 2[7/2]4(49322.56 cm‑1) → AIS(67707.61 cm‑1) which, by employing saturated radiation intensities provides the ionisation selectivity of above 1200 for 63Ni.

  5. A system for protecting the environment from ionising radiation: selecting reference fauna and flora, and the possible dose models and environmental geometries that could be applied to them.

    PubMed

    Pentreath, R J; Woodhead, D S

    2001-09-28

    In order to demonstrate, explicitly, that the environment can be protected with respect to controlled sources of ionising radiation, it is essential to have a systematic framework within which dosimetry models for fauna and flora can be used. And because of the practical limitations on what could reasonably be modelled and the amount of information that could reasonably be obtained, it is also necessary to limit the application of such models to a 'set' of fauna and flora within a reference' context. This paper, therefore, outlines the factors that will need to be considered to select such 'reference' fauna and flora, and describes some of the factors and constraints necessary to develop the associated dosimetry models. It also describes some of the most basic environmental geometrics within which the dose models could be set in order to make comparisons amongst different radiation sources.

  6. InterCardioRisk: a novel online tool for estimating doses of ionising radiation to occupationally-exposed medical staff and their associated health risks.

    PubMed

    Moriña, David; Grellier, James; Carnicer, Adela; Pernot, Eileen; Ryckx, Nick; Cardis, Elisabeth

    2016-09-01

    Those working in interventional cardiology and related medical procedures are potentially subject to considerable exposure to x-rays. Two types of tissue of particular concern that may receive considerable doses during such procedures are the lens of the eye and the brain. Ocular radiation exposure results in lens changes that, with time, may progress to partial or total lens opacification (cataracts). In the early stages, such opacities do not result in visual disability; the severity of such changes tends to increase progressively with dose and time until vision is impaired and cataract surgery is required. Scattered radiation doses to the eye lens of an interventional cardiologist in typical working conditions can exceed 34 μGy min(-1) in high-dose fluoroscopy modes and 3 μGy per image during image acquisition (instantaneous rate values) when radiation protection tools are not used. A causal relation between exposure to ionising radiation and increased risk of brain and central nervous system tumours has been shown in a number of studies. Although absorbed doses to the brain in interventional cardiology procedures are lower than those to the eye lens by a factor between 3.40 and 8.08 according to our simulations, doses to both tissues are among the highest occupational radiation doses documented for medical staff whose work involves exposures to x-rays. We present InterCardioRisk, a tool featuring an easy-to-use web interface that provides a general estimation of both cumulated absorbed doses experienced by medical staff exposed in the interventional cardiology setting and their estimated associated health risks. The tool is available at http://intercardiorisk.creal.cat.

  7. System-Level Radiation Hardening

    NASA Technical Reports Server (NTRS)

    Ladbury, Ray

    2014-01-01

    Although system-level radiation hardening can enable the use of high-performance components and enhance the capabilities of a spacecraft, hardening techniques can be costly and can compromise the very performance designers sought from the high-performance components. Moreover, such techniques often result in a complicated design, especially if several complex commercial microcircuits are used, each posing its own hardening challenges. The latter risk is particularly acute for Commercial-Off-The-Shelf components since high-performance parts (e.g. double-data-rate synchronous dynamic random access memories - DDR SDRAMs) may require other high-performance commercial parts (e.g. processors) to support their operation. For these reasons, it is essential that system-level radiation hardening be a coordinated effort, from setting requirements through testing up to and including validation.

  8. Introduction, audit and review of guidelines for delegated authorization of nuclear medicine investigations in compliance with the Ionising Radiation (Medical Exposure) Regulations 2000.

    PubMed

    Harris, A M; Greaves, C D; Taylor, C M; Taylor, C; Segasby, C A; Tindale, W B

    2003-08-01

    The introduction of the Ionising Radiation (Medical Exposure) Regulations 2000 in Great Britain required every nuclear medicine investigation to be justified by a practitioner holding an appropriate Administration of Radioactive Substances Committee (ARSAC) certificate. The task of authorizing the radiation exposure may be performed by the practitioner (direct authorization) or delegated to an appropriately trained operator working to written guidelines approved by the practitioner (delegated authorization). In this study, we look at the process of implementation, audit and review of a set of Delegated Authorization Guidelines (DAG). The process of drafting the DAG is outlined. Following the introduction of the DAG, an audit of nuclear medicine referrals was performed at two sites for a period of 3 months. Each referral was compared with the DAG to determine whether it matched the criteria set out. If it did not match, it was further categorized as being due to: (1) insufficient referral information; or (2) clinical indication not included in the DAG. All non-matching requests were reviewed by the practitioner. Four hundred and thirty-seven of 632 (69%) referrals fitted the DAG, 12% (n=75) required clarification from the referrer before fitting with the criteria and 19% (n=120) were directly authorized by the practitioner. From those referrals that were directly authorized, some additional indications were identified and the DAG were subsequently revised. In conclusion, a delegated authorization procedure for nuclear medicine investigations can be implemented successfully. Regular audit is essential. This study identified the need to improve the format of the request card and to obtain additional referral information from the referrer.

  9. A new approach to studying the effects of ionising radiation on single cells using FTIR synchrotron microspectroscopy

    NASA Astrophysics Data System (ADS)

    Lipiec, E.; Birarda, G.; Kowalska, J.; Lekki, J.; Vaccari, L.; Wiecheć, A.; Wood, B. R.; Kwiatek, W. M.

    2013-12-01

    The effect of ionizing radiation on single cells using a proton source was investigated using Fourier transform infrared (FTIR) microspectroscopy. The prostate cancer cells (DU-145) were irradiated by a specific number (50, 200, 400, 2000 and 4000) of protons per cell. Next after fixing the cells with 70% ethanol micro-FTIR spectra were obtained using both: (a) the synchrotron radiation source with a Mercury-Cadmium-Telluride (MCT) detector and (b) a globar source with a focal plane array (FPA) detector. FTIR spectra obtained from both instrumental configurations were analyzed independently to investigate the changes in the DNA phosphodiester region (1150-950 cm-1) of irradiated and control (untreated by ionizing radiation) cells. A Principal Component Analysis (PCA) scores plot revealed distinct clusters for all groups of irradiated cells, even for those irradiated by the smallest dose of protons. The dose-dependent changes in the relative intensities of DNA peak at 970 cm-1 (ribose-phosphate skeletal motions), along with a shift of the O-P-O band corresponding to the symmetric phosphodiester stretching mode at 1090 cm-1 were observed. The results demonstrate that FTIR spectroscopy is a promising tool to investigate DNA damage in single cells and may become an important tool in assessing cell damage following radiotherapy.

  10. Exposure of veterinary personnel to ionising radiation during bone scanning of horses by nuclear scintigraphy with 99mtechnetium methylene diphosphonate.

    PubMed

    Gatherer, M E; Faulkner, J; Voûte, L C

    2007-06-16

    The aim of this study was to compare the radiation doses received by the personnel drawing up and injecting the radiopharmaceutical and operating the nuclear scintigraphy equipment, and those restraining nine horses while they were being scanned during scintigraphic investigations of lameness. Sensitive electronic dosimeters were worn by the personnel and the doses they received during the administration of the radiopharmaceutical and during the period of image acquisition were recorded at intervals. On average, 90 per cent of the total doses were received during the period of image acquisition. There was no significant difference between the total dose received by the person who drew up and injected the radiopharmaceutical, and the person restraining the horse during its administration. However, the person holding the horse received approximately twice the dose received by the person operating the equipment during the period of image acquisition.

  11. An evaluation of the shielding effectiveness of lead aprons used in clinics for protection against ionising radiation from novel radioisotopes.

    PubMed

    Deb, Pradip; Jamison, Robert; Mong, Lisa; U, Paul

    2015-07-01

    The purpose of this study is to evaluate the effectiveness of personal radiation shields currently worn in hospital and other diagnostic environments. This study was performed with four different radioisotopes; (18)F, (99m)Tc, (124)I and (131)I. (18)F results showed a decrease in dose with 0.5-mm Pb shielding but the reduction provided does not warrant its use clinically. (124)I testing demonstrated that dose enhancement can occur in greater shield thicknesses. PET isotope (124)I can be adequately shielded using 0.25-mm Pb equivalent aprons but any higher thickness increase the wearer's dose. As a result more shielding does not always equal more protection. The (131)I test showed that no dose reduction occurred, even when tested with up to 1.25-mm Pb equivalent shielding. Novel radioisotopes being used in the laboratory and clinic should be individually tested as each requires specific shielding testing.

  12. Assessing the performance under ionising radiation of lead tungstate scintillators for EM calorimetry in the CLAS12 Forward Tagger

    NASA Astrophysics Data System (ADS)

    Fegan, S.; Auffray, E.; Battaglieri, M.; Buchanan, E.; Caiffi, B.; Celentano, A.; Colaneri, L.; D`Angelo, A.; De Vita, R.; Dormenev, V.; Fanchini, E.; Lanza, L.; Novotny, R. W.; Parodi, F.; Rizzo, A.; Sokhan, D.; Tarasov, I.; Zonta, I.

    2015-07-01

    The well-established technology of electromagnetic calorimetry using Lead Tungstate crystals has recently seen an upheaval, with the closure of one of the most experienced large-scale suppliers of such crystals, the Bogoroditsk Technical Chemical Plant (BTCP), which was instrumental in the development of mass production procedures for PWO-II, the current benchmark for this scintillator. Obtaining alternative supplies of Lead Tungstate crystals matching the demanding specifications of contemporary calorimeter devices now presents a significant challenge to detector research and development programmes. In this paper we describe a programme of assessment carried out for the selection, based upon the performance under irradiation, of Lead Tungstate crystals for use in the Forward Tagger device, part of the CLAS12 detector in Hall B at Jefferson Lab. The crystals tested were acquired from SICCAS, the Shanghai Institute of Ceramics, Chinese Academy of Sciences. The tests performed are intended to maximise the performance of the detector within the practicalities of the crystal manufacturing process. Results of light transmission, before and after gamma ray irradiation, are presented and used to calculate dk, the induced radiation absorption coefficient, at 420 nm, the peak of the Lead Tungstate emission spectrum. Results for the SICCAS crystals are compared with identical measurements carried out on Bogoroditsk samples, which were acquired for the Forward Tagger development program before the closure of the facility. Also presented are a series of tests performed to determine the feasibility of recovering radiation damage to the crystals using illumination from an LED, with such illumination available in the Forward Tagger from a light monitoring system integral to the detector.

  13. Deoxyribonucleic acid damage-associated biomarkers of ionising radiation: current status and future relevance for radiology and radiotherapy

    PubMed Central

    Rothkamm, K

    2013-01-01

    Diagnostic and therapeutic radiation technology has developed dramatically in recent years, and its use has increased significantly, bringing clinical benefit. The use of diagnostic radiology has become widespread in modern society, particularly in paediatrics where the clinical benefit needs to be balanced with the risk of leukaemia and brain cancer increasing after exposure to low doses of radiation. With improving long-term survival rates of radiotherapy patients and the ever-increasing use of diagnostic and interventional radiology procedures, concern has risen over the long-term risks and side effects from such treatments. Biomarker development in radiology and radiotherapy has progressed significantly in recent years to investigate the effects of such use and optimise treatment. Recent biomarker development has focused on improving the limitations of established techniques by the use of automation, increasing sensitivity and developing novel biomarkers capable of quicker results. The effect of low-dose exposure (0–100 mGy) used in radiology, which is increasingly linked to cancer incidences, is being investigated, as some recent research challenges the linear-no-threshold model. Radiotherapy biomarkers are focused on identifying radiosensitive patients, determining the treatment-associated risk and allowing for a tailored and more successful treatment of cancer patients. For biomarkers in any of these areas to be successfully developed, stringent criteria must be applied in techniques and analysis of data to reduce variation among reports and allow data sets to be accurately compared. Newly developed biomarkers can then be used in combination with the established techniques to better understand and quantify the individual biological response to exposures associated with radiology tests and to personalise treatment plans for patients. PMID:23659923

  14. Heat effects on DNA repair after ionising radiation: hyperthermia commonly increases the number of non-repaired double-strand breaks and structural rearrangements

    PubMed Central

    El-Awady, R. A.; Dikomey, E.; Dahm-Daphi, J.

    2001-01-01

    After ionising radiation double-strand breaks (dsb) are lethal if not repaired or misrepaired. Cell killing is greatly enhanced by hyperthermia and it is questioned here whether heat not only affects dsb repair capacity but also fidelity in a chromosomal context. dsb repair experiments were designed so as to mainly score non-homologous end joining, while homologous recombination was largely precluded. Human male G0 fibroblasts were either preheated (45°C, 20 min) or not before X-irradiation. dsb induction and repair were measured by conventional gel electrophoresis and an assay combining restriction digestion using a rare cutting enzyme (NotI) and Southern hybridisation, which detects large chromosomal rearrangements (>100 kb). dsb induction rate in an X-chromosomal NotI fragment was 4.8 × 10–3 dsb/Gy/Mb. Similar values were found for the genome overall and also when cells were preheated. After 50 Gy, fibroblasts were competent to largely restore the original restriction fragment size. Five per cent of dsb remained non-rejoined and 14% were misrejoined. Correct restitution of restriction fragments occurred preferably during the first hour but continued at a slow rate for 12–16 h. In addition, dsb appeared to misrejoin throughout the entire repair period. After hyperthermia the fractions of non-rejoined and misrejoined dsb were similarly increased to 13 and 51%, respectively. It is suggested that heat increases the probability of dsb being incorrectly rejoined but it is not likely to interfere with one dsb repair pathway in particular. PMID:11328880

  15. Students' Conceptions of Ionisation Energy: A Cross-Cultural Study

    ERIC Educational Resources Information Center

    Tan, Kim Chwee Daniel; Taber, Keith S.; Liu, Xiufeng; Coll, Richard K.; Lorenzo, Mercedes; Li, Jia; Goh, Ngoh Khang; Chia, Lian Sai

    2008-01-01

    Previous studies have indicated that A-level students in the UK and Singapore have difficulty learning the topic of ionisation energy. A two-tier multiple-choice instrument developed in Singapore in an earlier study, the Ionisation Energy Diagnostic Instrument, was administered to A-level students in the UK, advanced placement high school students…

  16. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Polarisation of the third harmonic generated by the pump field caused by collisions of electrons and ions in a plasma produced upon ionisation of a gas of excited hydrogen-like atoms

    NASA Astrophysics Data System (ADS)

    Silin, Viktor P.; Silin, Pavel V.

    2005-06-01

    The polarisation properties of the third harmonic of the pump field are considered in a plasma produced upon ionisation of excited hydrogen-like atoms, taking into account l degeneration. These properties depend on the degree of circular polarisation and intensity of the pump field. The threshold nature of the total circular polarisation of the third harmonic appearing in the case of partial circular polarisation of the pump is established. This effect represents the bifurcation of the total circular polarisation. The conditions required to confirm experimentally the predicted polarisation properties of radiation are discussed.

  17. Ionisation en couche K et effet biologique

    NASA Astrophysics Data System (ADS)

    L'Hoir, A.; Herve Du Penhoat, M. A.; Champion, C.; Fayard, B.; Touati, A.; Abel, F.; Politis, M. F.; Despiney-Bailly, I.; Sabatier, L.; Chetioui, A.

    1998-04-01

    Initial steps of radiation action mechanism on biological targets are still undnown. The strong correlation observed between inactivation cross sections by heavy ions and K-vacancy production cross sections has drawn the attention on this process. Although quite minor in the energy deposition of these particles, the K-ionization process gives rise to quite efficient ionization clusters. Values of K-ionization biological effectivenesses extracted from measured relative biological efficiencies of ultra soft X-rays support the idea of a major -may be a dominant- contribution of the K-vacancy process to the biological effect of heavy ions. Les étapes initiales des mécanismes d'effet biologique des radiations sont encore mal connues. La forte corrélation observée entre sections efficaces d'inactivation par ions lourds et sections efficaces d'ionisation K a attiré l'attention sur ce processus. Bien que de faible probabilité, l'ionisation K engendre des grappes d'ionisation très efficaces. Les valeurs de rendement létal extraites des efficacités biologiques relatives mesurées pour les rayonnements X ultra-mous suggèrent une contribution majeure -peut-être dominante- de l'ionisation K à l'effet biologique des ions.

  18. Effects of low-level radiation

    SciTech Connect

    Goldman, M.

    1993-12-31

    The effects of low-level radiation inhumans are usually estimated by extrapolation from high-level effects. Biological radiation effects from low-level radiation can be defined as those from doses below which no deterministic or graded biological responses will occur. In addition, the health consequences are almost all probabilistic. There is incomplete knowledge regarding the role of sex, age at exposure, co-factors, or environmental pollutants.

  19. The ionisation energy of cyclopentadienone: a photoelectron-photoion coincidence study

    NASA Astrophysics Data System (ADS)

    Ormond, Thomas K.; Hemberger, Patrick; Troy, Tyler P.; Ahmed, Musahid; Stanton, John F.; Ellison, G. Barney

    2015-08-01

    Imaging photoelectron photoion coincidence (iPEPICO) spectra of cyclopentadienone (C5H4=O and C5D4=O) have been measured at the Swiss Light Source Synchrotron (Paul Scherrer Institute, Villigen, Switzerland) at the Vacuum Ultraviolet (VUV) Beamline. Complementary to the photoelectron spectra, photoionisation efficiency curves were measured with tunable VUV radiation at the Chemical Dynamics Beamline at the Advanced Light Source Synchrotron (Lawrence Berkeley National Laboratory, Berkeley, CA, USA). For both experiments, molecular beams diluted in argon and helium were generated from the vacuum flash pyrolysis of o-phenylene sulphite in a resistively heated microtubular SiC flow reactor. The Franck-Condon profiles and ionisation energies were calculated at the CCSD(T) level of theory, and are in excellent agreement with the observed iPEPICO spectra. The ionisation energies of both cyclopentadienone-d0, IE(C5H4=O), and cyclopentadienone-d4, IE(C5D4=O), were observed to be the same: 9.41 ± 0.01 eV. The mass-selected threshold photoelectron spectrum (ms-TPES) of cyclopentadienone reveals that the C=C stretch in the ground state of the cation is excited upon ionisation, supporting computational evidence that the ground state of the cation is ? 2A2, and is in agreement with previous studies. However, the previously reported ionisation potential has been improved considerably in this work. In addition, since o-benzoquinone (o-O=C6H4=O and o-O=C6D4=O) is also produced in this process, its ms-TPES has been recorded. From the iPEPICO and photoionisation efficiency spectra, we infer an adiabatic ionisation energy of IE(o-O=C6H4=O) = 9.3 ± 0.1 eV, but the rather structureless spectrum indicates a strong change in geometry upon ionisation making this value less reliable.

  20. Concerns with low-level ionizing radiation

    SciTech Connect

    Yalow, R.S.

    1994-12-31

    Populations have been studied in geographic areas of increased natural radiation, in radiation-exposed workers, in patients medically exposed, and in accidental exposures. No reproducible evidence exists of harmful effects from increases in background radiation three to ten times the usual levels. There is no increase in leukemia or other cancers among American military participants in nuclear testing, no increase in leukemia or thyroid cancer among medical patients receiving {sup 131}I for diagnosis or treatment of hypothyroidism, and no increase in lung cancer among nonsmokers exposed to increased radon in the home. The association of radiation with the atomic bomb and with excessive regulatory and health physics as-low-as-reasonably-achievable (ALARA) radiation levels practices has created a climate of fear about the dangers of radiation at any level. However, there is no evidence that radiation exposures at the levels equivalent to medical usage are harmful. The unjustified excessive concern with radiation at any level, however, precludes beneficial uses of radiation and radioactivity in medicine, science, and industry.

  1. Outdoor radiofrequency radiation levels in the West Bank-Palestine.

    PubMed

    Lahham, Adnan; Hammash, Alaa

    2012-05-01

    This work presents the results of exposure levels to radio frequency (RF) emission from different sources in the environment of the West Bank-Palestine. These RF emitters include FM and TV broadcasting stations and mobile phone base stations. Power densities were measured at 65 locations distributed over the West Bank area. These locations include mainly centres of the major cities. Also a 24 h activity level was investigated for a mobile phone base station to determine the maximum activity level for this kind of RF emitters. All measurements were conducted at a height of 1.7 m above ground level using hand held Narda SRM 3000 spectrum analyzer with isotropic antenna capable of collecting RF signals in the frequency band from 75 MHz to 3 GHz. The average value of power density resulted from FM radio broadcasting in all investigated locations was 0.148 μW cm(-2), from TV broadcasting was 0.007 μW cm(-2) and from mobile phone base station was 0.089 μW cm(-2). The maximum total exposure evaluated at any location was 3.86 μW cm(-2). The corresponding exposure quotient calculated for this site was 0.02. This value is well below unity indicating compliance with the International Commission on non-ionising Radiation protection guidelines. Contributions from all relevant RF sources to the total exposure were evaluated and found to be ~62 % from FM radio, 3 % for TV broadcasting and 35 % from mobile phone base stations. The average total exposure from all investigated RF sources was 0.37 μW cm(-2).

  2. Assessment of RF radiation levels in the vicinity of 60 GSM mobile phone base stations in Iran.

    PubMed

    Nayyeri, Vahid; Hashemi, Seyed Mohammad; Borna, Maryam; Jalilian, Hamid-Reza; Soleimani, Mohammad

    2013-07-01

    Increasing development of mobile communication infrastructure while enhancing availability of the technology raises concerns among the public, who see more cell towers erected each day, about possible health effects of electromagnetic radiations. Thereon, a survey of radio-frequency radiation from 60 GSM base stations was carried out in Tehran, Iran at several places mostly located in major medical and educational centres. Measurements were performed at 15 locations near each base station site, i.e. 900 locations in total. Since there are other RF radiation sources such as broadcasting services whose carrier frequencies are <3 GHz, the whole band of 27 MHz to 3 GHz has been assessed for hazardous exposures as well. The results were compared with the relevant guideline of International Commission on Non-Ionising Radiation Protection and that of Iran, confirming radiation exposure levels being satisfactorily below defined limits and non-detrimental.

  3. Application of positive ion chemical ionisation and tandem mass spectrometry combined with gas chromatography to the trace level analysis of ethyl carbamate in bread.

    PubMed

    Hamlet, Colin G; Jayaratne, Sanal M; Morrison, Carol

    2005-01-01

    A rapid, sensitive and selective method has been developed and validated for the analysis of the contaminant ethyl carbamate (EC) in bread products at the part-per-billion level. The new procedure uses positive ion chemical ionisation (PICI) and tandem mass spectrometry (MS/MS), combined with gas chromatography (GC), on a 'bench-top' triple-quadrupole mass spectrometer. Ammonia was the PICI reagent gas of choice because of its ability to produce abundant [M+H]+ and [M+NH4]+ ions from EC and deuterium-labelled EC (LEC) used as an internal standard. For identification and quantification, selected reaction monitoring (SRM) was used to follow the precursor-to-product ion transitions of m/z 107 --> 90, m/z 107 --> 62 and m/z 90 --> 62 for EC, as well as m/z 112 --> 63 for the LEC internal standard. The limits of detection and quantification were 0.6 and 1.2 microg kg(-1), respectively, and the recovery of the method was 101 +/- 10% at 10 microg kg(-1) and 98 +/- 5% at 100 microg kg(-1). The precision of the method, established under conditions of intermediate reproducibility, did not exceed a relative standard deviation of 7%. The quantitative performance of the new GC/PICI-SRM procedure compared favourably with that of a reference method based on GC/MS and selected ion monitoring (correlation coefficient, r = 0.997). However, the new method had the advantages of reduced sample preparation time, improved sensitivity and unambiguous identification of EC at all concentrations. Application of the new method to the analysis of 50 UK breads showed that levels of EC ranged from 0.6 to 2.3 microg kg(-1) in retail products and from 3.1 to 12.2 microg kg(-1) for breads prepared using domestic breadmaking machines (dry weight basis). Toasting bread in a domestic toaster led to increases of between two- and three-fold in mean EC concentrations.

  4. Radiative Strength Functions and Level Densities

    SciTech Connect

    Schiller, A; Becker, J A; Bernstein, L A; Voinov, A; Guttormsen, M; Hjorth-Jensen, M; Rekstad, J; Siem, S; Mitchell, G E; Tavukcu, E

    2002-08-28

    Radiative strength functions and level densities have been extracted from primary {gamma}-ray spectra for {sup 27,28}Si, {sup 56,57}Fe, {sup 96,97}Mo, and several rare earth nuclei. An unexpectedly strong ({approx} 1 mb MeV) resonance at 3 MeV in the radiative strength function has been observed for well-deformed rare earth nuclei. The physical origin of this resonance and its connection to the scissors mode is discussed.

  5. Ultraviolet radiation levels during the Antarctic spring

    NASA Technical Reports Server (NTRS)

    Frederick, John E.; Snell, Hilary E.

    1988-01-01

    The decrease in atmospheric ozone over Antarctica during spring implies enhanced levels of ultraviolet (UV) radiation received at the earth's surface. Model calculations show that UV irradiances encountered during the occurrence of an Antarctic 'ozone hole' remain less than those typical of a summer solstice at low to middle latitudes. However, the low ozone amounts observed in October 1987 imply biologically effective irradiances for McMurdo Station, Antarctica, that are comparable to or greater than those for the same location at December solstice. Life indigenous to Antarctica thereby experiences a greatly extended period of summerlike UV radiation levels.

  6. Background compensation for a radiation level monitor

    DOEpatents

    Keefe, D.J.

    1975-12-01

    Background compensation in a device such as a hand and foot monitor is provided by digital means using a scaler. With no radiation level test initiated, a scaler is down-counted from zero according to the background measured. With a radiation level test initiated, the scaler is up-counted from the previous down-count position according to the radiation emitted from the monitored object and an alarm is generated if, with the scaler having crossed zero in the positive going direction, a particular number is exceeded in a specific time period after initiation of the test. If the test is initiated while the scale is down-counting, the background count from the previous down- count stored in a memory is used as the initial starting point for the up-count.

  7. Radiation exposure at ground level by secondary cosmic radiation.

    PubMed

    Wissmann, F; Dangendorf, V; Schrewe, U

    2005-01-01

    The contribution of the charged component of secondary cosmic radiation to the ambient dose equivalent H*(10) at ground level is investigated using the muon detector MUDOS and a TEPC detector surrounded by the coincidence detector CACS to identify charged particles. The ambient dose equivalent rate H*(10)T as measured with the TEPC/CACS is used to calibrate the MUDOS count rate in terms of H*(10). First results from long-term measurements at the PTB reference site for ambient radiation dosimetry are reported. The air pressure corrected dose rate shows, as expected, a strong correlation with the neutron count rate as measured with the Kiel neutron monitor. The measured seasonal variations exhibit a negative correlation with the temperature changes in the upper layers of the atmosphere where the ground level muons are produced.

  8. Vital parameters related low level laser radiation

    NASA Astrophysics Data System (ADS)

    Palmieri, Beniamino; Capone, Stefania

    2011-08-01

    The first work hypotesis is that biosensors on the patient detecting heart, breath rate and skin parameters, modulate laser radiation to enhance the therapeutic outcome; in the second work hypotesis: biofeedback could be effective, when integrated in the low level laser energy release.

  9. Optimisation of radiolysis of Reactive Red 120 dye in aqueous solution using ionising (60)Co gamma radiation by response surface methodology.

    PubMed

    Padmanaban, V C; Giri Nandagopal, M S; Achary, Anant; Vasudevan, V N; Selvaraju, N

    2016-01-01

    In recent years, employing radiation technology is gaining great interest in degradation of industrial effluents. In this work the possibility of using gamma irradiation to degrade Reactive Red 120 (C.I.292775) was explored. The effects of pH, dose of gamma irradiation and concentration of dye were examined and their interaction were also established based on their response. For the analysis and optimisation of variables, three factor three level Box-Wilson face centred central composite design (CCF) was used. Analysis of variance with R(2) = 0.9988, adjusted R(2) = 0.9981 and the adequate precision value of 122.303 indicates that the CCF model can be used. The coefficient of variation (0.54%) indicates the reliability of the model. The dose of gamma irradiation (kGy) and the concentration of dye (mg/L) showed significant effects on the degradation of RR 120, while a difference of 6 to 10% degradation was observed in extending the pH towards the acid or alkali range from pH 7.00. The maximum concentration of dye degraded was observed as 347.509 mg/L at initial pH: 7.0, dose of gamma irradiation: 5.94 kGy and initial concentration of dye: 500 mg/L. This predicted value was found to be in agreement with the experimental value on the optimised conditions.

  10. Epidemiological investigations of aircrew: an occupational group with low-level cosmic radiation exposure.

    PubMed

    Zeeb, Hajo; Hammer, Gaël P; Blettner, Maria

    2012-03-01

    Aircrew and passengers are exposed to low-level cosmic ionising radiation. Annual effective doses for flight crew have been estimated to be in the order of 2-5 mSv and can attain 75 mSv at career end. Epidemiological studies in this occupational group have been conducted over the last 15-20 years, usually with a focus on radiation-associated cancer. These studies are summarised in this note. Overall cancer risk was not elevated in most studies and subpopulations analysed, while malignant melanoma, other skin cancers and breast cancer in female aircrew have shown elevated incidence, with lesser risk elevations in terms of mortality. In some studies, including the large German cohort, brain cancer risk appears elevated. Cardiovascular mortality risks were generally very low. Dose information for pilots was usually derived from calculation procedures based on routine licence information, types of aircraft and routes/hours flown, but not on direct measurements. However, dose estimates have shown high validity when compared with measured values. No clear-cut dose-response patterns pointing to a higher risk for those with higher cumulative doses were found. Studies on other health outcomes have shown mixed results. Overall, aircrew are a highly selected group with many specific characteristics and exposures that might also influence cancers or other health outcomes. Radiation-associated health effects have not been clearly established in the studies available so far.

  11. Monitoring radiation belt particle precipitation - automatic detection of enhanced transient ionisation in the lower plasmasphere using subionospheric narrow band VLF signals

    NASA Astrophysics Data System (ADS)

    Steinbach, P.; Lichtenberger, J.; Ferencz, Cs.

    2009-04-01

    Signals of naval VLF transmitters, propagating long distances along the Earth-ionosphere waveguide (EIWG) have been widely applied as effective tools for monitoring transient ionization at mesospheric altitudes. Perturbations in recorded amplitude and/or phase data series of stable frequency signals may refer to the effect of transient enhanced ionization in the EIWG, due to e.g. loss-cone precipitation of trapped energetic electrons (Carpenter et al., 1984, Dowden and Adams, 1990), burst of solar plasma particles (Clilverd et al., 2001). The contribution of precipitating particles are thought to be substantial in certain Sun-to-Earth energy flow processes in the upper atmosphere (Rodger et al., 2005). Narrow band VLF measuring network has been set up, developed and operated in Hungary, running in the last decade almost continuously, dedicated to monitor ionization enhancement regions along numerous transmitter-receiver paths. This setup is based on Omnipal and Ultra-MSK equipment, logging amplitude and phase data of received signals, sampled at frequencies of selected VLF transmitters. Signal trajectories, selected for recording represent proper configuration to survey transient ionization caused by energetic particles in the sub-polar region, such as effect of scattered particles of the inner radiation belt. Reprocessing of the mass archived recordings has been started using a newly developed signal processing code, detecting and classifying different sort of perturbations automatically on narrow band VLF series. Occurrence rates, daily and seasonal variation, statistics of transient ionization enhancements, their geographic distribution within the surveyed range and time period, and correlation with intense geomagnetic and/or Solar event is yielded by this analysis. References: Carpenter, D.L., Inan, U.S., Trimpi, M.L., Helliwell, R.A., and Katsufrakis, J.P.: Perturbations of subionospheric LF and MF signals due to whistler-induced electron precipitation burst

  12. Portable radiation monitor assures cleanup levels

    SciTech Connect

    Hasbach, A.

    1995-10-01

    Sevenson Environmental Services, Niagara Falls, NY, is a contractor at the EPA Superfund site at Montclair, NJ. Working with the Army Corps of Engineers, they are cleaning up radium waste left by a watch factory from the early 1900s. With the hazards of radium unknown at the time, radium in its many forms was spread throughout the region. As sand, it was used for concrete, as ash for packing material, and sometimes as landfill. When a hazardous site is found, Sevenson excavates the contaminated material and replaces it with clean fill. A Reuter-Stokes RSS-112 portable gamma monitoring system is used to ensure radiation is at sample background levels. Using a pressurized ionization chamber (PIC), the RSS-112 measures exposure rates from background to serious alarm levels over a wide energy range. Measurement takes place every five seconds. The portable system is 50% lighter than its predecessor and includes 300 point data storage, graphic display panel, 120-hour battery life between recharges, and RS-232 interface for downloading to a PC.

  13. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Change in the ionisation state of a near-surface laser-produced aluminium plasma in double-pulse ablation modes

    NASA Astrophysics Data System (ADS)

    Burakov, V. S.; Bokhonov, A. F.; Nedel'ko, M. I.; Tarasenko, N. V.

    2003-12-01

    The near-surface plasma produced upon irradiation of an aluminium target by two successive laser pulses with nonresonance and resonance wavelengths is studied by the spectroscopic and probe-assisted methods. The feasibility of increasing the ion fraction in the laser-produced plasma in double-pulse ablation modes is demonstrated. The conditions are determined under which processes on the surface as well as selective excitation and ionisation in the plasma have a determining effect on the formation of its ionisation state.

  14. Ionisers in the management of bronchial asthma.

    PubMed Central

    Nogrady, S G; Furnass, S B

    1983-01-01

    Because of recent interest in the possible benefits to asthmatic patients of negative ion generators and the largely uncontrolled and inconclusive nature of earlier studies a double blind crossover study of this treatment was carried out in 20 subjects with stable asthma over six months. After an initial two week period without an ioniser, active or placebo ionisers were installed in subjects' bedrooms for two eight week periods separated by a four week "washout" period when no ioniser was present. The study was completed by a final four week period when no ioniser was present. Subjects were randomly allocated to receive an active or a placebo ioniser first. Subjects recorded their peak expiratory flow rate (PEFR) twice daily, completed a daily symptom score questionnaire, and noted any treatment they took on a diary card. Recordings were completed throughout the trial. Ion counts and dust concentrations were measured in subjects' bedrooms during the study. Mean ion counts rose considerably when ionisers were activated (p less than 0.001). There were no significant differences in PEFR, symptom score, or consumption of medication between the periods that active ionisers and either no ionisers or placebo ionisers were in operation. This study has failed to show a statistically significant benefit in asthmatic subjects from the use of negative ion generators. PMID:6364442

  15. Galactic cosmic ray radiation levels in spacecraft on interplanetary missions

    NASA Technical Reports Server (NTRS)

    Shinn, J. L.; Nealy, J. E.; Townsend, L. W.; Wilson, J. W.; Wood, J.S.

    1994-01-01

    Using the Langley Research Center Galactic Cosmic Ray (GCR) transport computer code (HZETRN) and the Computerized Anatomical Man (CAM) model, crew radiation levels inside manned spacecraft on interplanetary missions are estimated. These radiation-level estimates include particle fluxes, LET (Linear Energy Transfer) spectra, absorbed dose, and dose equivalent within various organs of interest in GCR protection studies. Changes in these radiation levels resulting from the use of various different types of shield materials are presented.

  16. Simulation studies on a prototype ionisation chamber for measurement of personal dose equivalent, Hp(10).

    PubMed

    Cardoso, J; Carvalho, A F; Oliveira, C

    2007-01-01

    A prototype ionisation chamber for direct measurement of the personal dose equivalent, Hp(10), similar to the one developed by the Physikalisch-Technische Bundesantalt (PTB), was designed and constructed by the Metrological Laboratory of Ionizing Radiation (LMRI) of Nuclear and Technological Institute (ITN). Tests already performed have shown that the behaviour of this chamber is very similar to the PTB chamber, mainly the energy dependence for the X-ray radiation qualities of the ISO 4037-1 narrow series N-30, N-40, N-60, N-80, N-100 and N-120 and also for gamma radiation of 137Cs and 60Co. However, the results obtained also show a dependence on the energy and angles of incident radiation and a low magnitude of the electrical response of the ionisation chamber. In order to optimise the performance of the chamber, the LMRI initiated numerical simulation of this ionisation chamber by Monte Carlo method using the MCNPX code.

  17. Characterisation of ship diesel primary particulate matter at the molecular level by means of ultra-high-resolution mass spectrometry coupled to laser desorption ionisation--comparison of feed fuel, filter extracts and direct particle measurements.

    PubMed

    Rüger, Christopher P; Sklorz, Martin; Schwemer, Theo; Zimmermann, Ralf

    2015-08-01

    In this study, positive-mode laser desorption-ionisation ultra-high-resolution mass spectrometry (LDI-FT-ICR-MS) was applied to study combustion aerosol samples obtained from a ship diesel engine as well as the feed fuel, used to operate the engine. Furthermore, particulate matter was sampled from the exhaust tube using an impactor and analysed directly from the impaction foil without sample treatment. From the high percentage of shared sum formula as well as similarities in the chemical spread of aerosol and heavy fuel oil, results indicate that the primary aerosol mainly consists of survived, unburned species from the feed fuel. The effect of pyrosynthesis could be observed and was slightly more pronounced for the CH-class compared to other compound classes, but in summary not dominant. Alkylation pattern as well as the aromaticity distribution, using the double bond equivalent, revealed a shift towards lower alkylation state for the aerosol. The alkylation pattern of the most dominant series revealed a higher correlation between different aerosol samples than between aerosol and feed samples. This was confirmed by cluster analysis. Overall, this study shows that LDI-FT-ICR-MS can be successfully applied for the analysis of combustion aerosol at the molecular level and that sum formula information can be used to identify chemical differences between aerosol and fuel as well as between different size fractions of the particulate matter.

  18. Modelling of ground-level UV radiation

    NASA Astrophysics Data System (ADS)

    Koepke, P.; Schwander, H.; Thomalla, E.

    1996-06-01

    A number of modifications were made on the STAR radiation transmission model for greater ease of use while keeping its fault liability low. The improvements concern the entire aerosol description function of the model, the option of radiation calculation for different receiver geometries, the option of switching off temperature-dependent ozone absorption, and simplications of the STAR menu. The assets of using STAR are documented in the studies on the accuracy of the radiation transmission model. One of these studies gives a detailed comparison of the present model with a simple radiation model which reveals the limitations of approximation models. The other examines the error margin of radiation transmission models as a function of the input parameters available. It was found here that errors can be expected to range between 5 and 15% depending on the quality of the input data sets. A comparative study on the values obtained by measurement and through the model proved this judgement correct, the relative errors lying within the predicted range. Attached to this final report is a comprehensive sensitivity study which quantifies the action of various atmospheric parameters relevant to UV radiation, thus contributing to an elucidation of the process.

  19. Responses to the low-level-radiation controversy

    SciTech Connect

    Bond, V.P.

    1981-10-07

    Some data sets dealing with the hazards of low-level radiation are discussed. It is concluded that none of these reports, individually or collectively, changes appreciably or even significantly the evaluations of possible low-level radiation effects that have been made by several authoritative national and international groups. (ACR)

  20. Physical models implemented in the GEANT4-DNA extension of the GEANT-4 toolkit for calculating initial radiation damage at the molecular level.

    PubMed

    Villagrasa, C; Francis, Z; Incerti, S

    2011-02-01

    The ROSIRIS project aims to study the radiobiology of integrated systems for medical treatment optimisation using ionising radiations and evaluate the associated risk. In the framework of this project, one research focus is the interpretation of the initial radio-induced damage in DNA created by ionising radiation (and detected by γ-H2AX foci analysis) from the track structure of the incident particles. In order to calculate the track structure of ionising particles at a nanometric level, the Geant4 Monte Carlo toolkit was used. Geant4 (Object Oriented Programming Architecture in C++) offers a common platform, available free to all users and relatively easy to use. Nevertheless, the current low-energy threshold for electromagnetic processes in GEANT4 is set to 1 keV (250 eV using the Livermore processes), which is an unsuitable value for nanometric applications. To lower this energy threshold, the necessary interaction processes and models were identified, and the corresponding available cross sections collected from the literature. They are mostly based on the plane-wave Born approximation (first Born approximation, or FBA) for inelastic interactions and on semi-empirical models for energies where the FBA fails (at low energies). In this paper, the extensions that have been introduced into the 9.3 release of the Geant4 toolkit are described, the so-called Geant4-DNA extension, including a set of processes and models adapted in this study and permitting the simulation of electron (8 eV-1 MeV), proton (100 eV-100 MeV) and alpha particle (1 keV-10 MeV) interactions in liquid water.

  1. Ionised outflows in z ~ 2.4 quasar host galaxies

    NASA Astrophysics Data System (ADS)

    Carniani, S.; Marconi, A.; Maiolino, R.; Balmaverde, B.; Brusa, M.; Cano-Díaz, M.; Cicone, C.; Comastri, A.; Cresci, G.; Fiore, F.; Feruglio, C.; La Franca, F.; Mainieri, V.; Mannucci, F.; Nagao, T.; Netzer, H.; Piconcelli, E.; Risaliti, G.; Schneider, R.; Shemmer, O.

    2015-08-01

    Aims: Outflows driven by active galactic nuclei (AGN) are invoked by galaxy evolutionary models to quench star formation and to explain the origin of the relations observed locally between super-massive black holes and their host galaxies. We here aim to detect extended ionised outflows in luminous quasars, where we expect the highest activity both in star formation and in black-hole accretion. Currently, there are only a few studies based on spatially resolved observations of outflows at high redshift, z > 2. Methods: We analysed a sample of six luminous (L > 1047 erg/s) quasars at z ~ 2.4, observed in H-band using the near-IR integral field spectrometer SINFONI at the VLT. We performed a kinematic analysis of the [Oiii] emission line at λ = 5007 Å. Results: We detect fast, spatially extended outflows in five out of six targets. [Oiii]λ5007 has a complex gas kinematic, with blue-shifted velocities of a few hundreds of km s-1 and line widths up to 1500 km s-1. Using the spectroastrometric method, we infer a size of the ionised outflows of up to ~2 kpc. The properties of the ionised outflows, mass outflow rate, momentum rate, and kinetic power, are correlated with the AGN luminosity. The increase in outflow rate with increasing AGN luminosity is consistent with the idea that a luminous AGN pushes away the surrounding gas through fast outflows that are driven by radiation pressure, which depends on the emitted luminosity. Conclusions: We derive mass outflow rates of about 6-700 M⊙ yr-1 for our sample, which are lower than those observed in molecular outflows. The physical properties of ionised outflows show dependences on AGN luminosity that are similar to those of molecular outflows, but indicate that the mass of ionised gas is lower than that of molecular outflows. Alternatively, this discrepancy between ionised and molecular outflows could be explained with different acceleration mechanisms. Based on Observations collected at the European Organisation for

  2. Blood lead levels in radiator repair workers in Colorado.

    PubMed

    Dalton, C B; McCammon, J B; Hoffman, R E; Baron, R C

    1997-01-01

    A laboratory-based blood lead surveillance system in Colorado identified radiator repair workers as having the highest blood lead levels of all worker groups reported. A survey of 42 radiator repair shops in ten locales throughout Colorado was undertaken to estimate the prevalence of workers with elevated blood lead levels > 25 micrograms/dL. The survey was designed to test the sensitivity of the surveillance system and to assess working conditions and practices in the radiator repair industry in Colorado. Of 63 workers, 39 (62%) had blood lead levels > 25 micrograms/dL. The sensitivity of the surveillance system for detecting radiator repair workers with elevated blood lead levels was estimated at 11%. None of the radiator repair shops had adequate local exhaust ventilation. Work practice and engineering modifications are needed to reduce lead exposure in this industry.

  3. Radiation threshold levels for noise degradation of photodiodes. Technical report

    SciTech Connect

    Aukerman, L.W.; Vernon, F.L.; Song, Y.

    1986-09-30

    Space radiation can increase the noise of photodiodes as a result of either a sustained ionizing-dose-rate effect or displacement damage. Elementary, straightforward models are presented for calculating radiation threshold levels and rad hit susceptibility. Radiation-effects experiments that verify these models are discussed. Calculations for room-temperature silicon p-i-n photodetectors, an avalanche photodiode, and a hypothetical cooled staring detector indicate that this damage mechanism should not be ignored for space and nuclear environments.

  4. Radiation levels on empty cylinders containing heel material

    SciTech Connect

    Shockley, C.W.

    1991-12-31

    Empty UF{sub 6} cylinders containing heel material were found to emit radiation levels in excess of 200 mr/hr, the maximum amount stated in ORO-651. The radiation levels were as high as 335 mr/hr for thick wall (48X and 48Y) cylinders and 1050 mr/hr for thin wall (48G and 48H) cylinders. The high readings were found only on the bottom of the cylinders. These radiation levels exceeded the maximum levels established in DOT 49 CFR, Part 173.441 for shipment of cylinders. Holding periods of four weeks for thick-wall cylinders and ten weeks for thin-wall cylinders were established to allow the radiation levels to decay prior to shipment.

  5. Effects of low levels of radiation on humans

    SciTech Connect

    Auxier, J.A.

    1981-01-01

    The state of knowledge on effects of low-level ionizing radiations on humans is reviewed. Several problems relating to dose thresholds or lack of thresholds for several types of cancer and high LET radiations and the effects of fractionation and dose protection are discussed. (ACR)

  6. Radiation levels in the SSC interaction regions

    SciTech Connect

    Groom, D.E.

    1988-06-10

    The radiation environment in a typical SSC detector has been evaluated using the best available particle production models coupled with Monte Carlo simulations of hadronic and electromagnetic cascades. The problems studied include direct charged particle dose, dose inside a calorimeter from the cascades produced by incident photons and hadrons, the flux of neutrons and photons backscattered from the calorimeter into a central cavity, and neutron flux in the calorimeter. The luminosity lifetime at the SSC is dominated by collision losses in the interaction regions, where the luminosity is equivalent to losing an entire full-energy proton beam into the apparatus every six days. The result of an average p-p collision can be described quite simply. The mean charged multiplicity is about 110, and the particles are distributed nearly uniformly in pseudorapidity ({eta}) over all the angles of interest. The transverse momentum distribution is independent of angle, and for our purposes may be written as p{perpendicular}exp(-p{perpendicular}/{beta}). The mean value of p{perpendicular} may be as high as 0.6 GeV/c. Most of the radiation is produced by the very abundant low-p{perpendicular} particles. The dose or neutron fluence produced by individual particles in this energy region are simulated over a wide variety of conditions, and several measurements serve to confirm the simulation results. In general, the response (a dose, fluence, the number of backscattered neutrons, etc.) for an incident particle of momentum p can be parameterized in the form Np{sup {alpha}}, where 0.5 < {alpha}< 1.0. The authors believe most of their results to be accurate to within a factor of two or three, sufficiently precise to serve as the basis for detailed designs.

  7. Examining a link between SPEs and ground level radiation

    NASA Astrophysics Data System (ADS)

    Overholt, Andrew

    2015-01-01

    Researchers have previously found a correlation between solar proton events (SPEs) and congenital malformations (CMs). A similar correlation has also been found between long term solar variability and CMs. We examine the ionizing radiation dose from these events as well as the largest events on record to determine whether these events are capable of producing these effects. We show that the total ionizing radiation dose (consisting of neutrons and muons) at ground level is insufficient for production of the observed increases in CM rate under the current paradigm regarding ionizing radiation from muons and neutrons. Current research on the subject shows that our assumptions regarding muonic ionizing radiation may be underestimating their biologic effect. We recommend further experimentation regarding the radiation dose due to muons, as this may prove to be a more substantial contribution to our radiation environment than previously assumed.

  8. Network-level fallout radiation effects assessment. Final report

    SciTech Connect

    Not Available

    1991-05-01

    National Security calls for the ability to maintain communication capabilities in times of national disaster, which could include a nuclear attack. Nuclear detonation has two basic by-products for which telecommunication equipments are susceptible to damage. These are electromagnetic pulse (EMP) and fallout radiation. The purposes of the EMP Mitigation Program are to analyze and to lessen the effects of EMP and fallout radiation on national telecommunications resources. Fallout radiation occurs after the initial intense high-frequency EMP, and is the subject of this analysis. Fallout radiation is the residual radiation that remains in the atmosphere after a nuclear blast, and which can be carried by weather conditions to locations far from the detonation point. This analysis focuses on the effects of fallout radiation on the telecommunications network of the American Telephone and Telegraph Co. (AT and T). This assessment of AT and T-network's communications-capabilities uses a network-level approach to assess fallout-radiation effects on the network's performance. The approach used was developed for assessing network-level EMP effects on Public Switched Network communication capabilities. Details are given on how EMP assessments utilize this method. Equipment-level fallout-radiation survivability data is also required.

  9. Effects of high vs low-level radiation exposure

    SciTech Connect

    Bond, V.P.

    1983-01-01

    In order to appreciate adequately the various possible effects of radiation, particularly from high-level vs low-level radiation exposure (HLRE, vs LLRE), it is necessary to understand the substantial differences between (a) exposure as used in exposure-incidence curves, which are always initially linear and without threshold, and (b) dose as used in dose-response curves, which always have a threshold, above which the function is curvilinear with increasing slope. The differences are discussed first in terms of generally familiar nonradiation situations involving dose vs exposure, and then specifically in terms of exposure to radiation, vs a dose of radiation. Examples are given of relevant biomedical findings illustrating that, while dose can be used with HLRE, it is inappropriate and misleading the LLRE where exposure is the conceptually correct measure of the amount of radiation involved.

  10. Biophysical modelling of early and delayed radiation damage at chromosome level

    NASA Astrophysics Data System (ADS)

    Andreev, S.; Eidelman, Y.

    Exposure by ionising radiation increases cancer risk in human population Cancer is thought to originate from an altered expression of certain number of specific genes It is now widely recognised that chromosome aberrations CA are involved in stable change in expression of genes by gain or loss of their functions Thus CA can contribute to initiation or progression of cancer Therefore understanding mechanisms of CA formation in the course of cancer development might be valuable tool for quantification and prognosis of different stages of radiation carcinogenesis Early CA are defined as aberrations induced in first post-irradiation mitotic cycle The present work describes the original biophysical technique for early CA modelling It includes the following simulation steps the ionising particle track structure the structural organisation of all chromosomes in G 0 G 1 cell nucleus spatial distribution of radiation induced DNA double-strand breaks dsb within chromosomes dsb rejoining and misrejoining modelling cell cycle taking into account mitotic delay which results in complex time dependence of aberrant cells in first mitosis The results on prediction of dose-response curves for simple and complex CA measured in cells undergoing first division cycle are presented in comparison with recent experimental data There is increasing evidence that CA are also observed in descendents of irradiated cells many generations after direct DNA damage These delayed CA or chromosome instability CI are thought to be a manifestation of genome

  11. Gastrointestinal radiation injury: Prevention and treatment

    PubMed Central

    Shadad, Abobakr K; Sullivan, Frank J; Martin, Joseph D; Egan, Laurence J

    2013-01-01

    With the recent advances in detection and treatment of cancer, there is an increasing emphasis on the efficacy and safety aspects of cancer therapy. Radiation therapy is a common treatment for a wide variety of cancers, either alone or in combination with other treatments. Ionising radiation injury to the gastrointestinal tract is a frequent side effect of radiation therapy and a considerable proportion of patients suffer acute or chronic gastrointestinal symptoms as a result. These side effects often cause morbidity and may in some cases lower the efficacy of radiotherapy treatment. Radiation injury to the gastrointestinal tract can be minimised by either of two strategies: technical strategies which aim to physically shift radiation dose away from the normal intestinal tissues, and biological strategies which aim to modulate the normal tissue response to ionising radiation or to increase its resistance to it. Although considerable improvement in the safety of radiotherapy treatment has been achieved through the use of modern optimised planning and delivery techniques, biological techniques may offer additional further promise. Different agents have been used to prevent or minimize the severity of gastrointestinal injury induced by ionising radiation exposure, including biological, chemical and pharmacological agents. In this review we aim to discuss various technical strategies to prevent gastrointestinal injury during cancer radiotherapy, examine the different therapeutic options for acute and chronic gastrointestinal radiation injury and outline some examples of research directions and considerations for prevention at a pre-clinical level. PMID:23345942

  12. Predicted levels of human radiation tolerance extrapolated from clinical studies of radiation effects

    NASA Technical Reports Server (NTRS)

    Lushbaugh, C. C.

    1972-01-01

    Results of clinical studies of radiation effects on man are used to evaluate space radiation hazards encountered during manned space travel. Considered are effects of photons as well as of mixed fission neutrons and gamma irradiations in establishing body radiosensitivity and tolerance levels. Upper and lower dose-response-time relations for acute radiation syndromes in patients indicate that man is more than sufficiently radioresistant to make the risks of an early radiation effect during one short space mission intangibly small in relation to the other nonradiation risks involved.

  13. Is Exposure to Low Radiation Levels Good For You?

    NASA Astrophysics Data System (ADS)

    Dimitroyannis, Dimitri

    1996-05-01

    Little is known about the biological effects of very low levels of ionizing radiation. We propose an experiment to compare cell response to such low radiation levels, using fast replicating yeast cells. Saccharomyces Cerevisae (SC), a type of yeast, is an eukariotic unicellular microorganism with a mean cell generation time of 90 min. Its genetic organization is similar to that of superior organisms, but at the same time is very easy to handle, with special reference to its genetic analysis. Certain CS strains are widely employed for mutagenesis studies. We propose to expose simultaneously three indentical CS cultures for a period of up to a few weeks (100s of cell generations): to natural backgroung (NB) ionizing radiation (at a ground level lab), to sub-NB level (underground) and to supra-NB level (at a high altitude). At the end of the exposure we will chemically challenge the cultured cells with methyl-methane-sulphonate (MMS), a standard chemical mutagen. Mitotic recombination frequency in the MMS exposed cultures is an index of early DNA damage induction at high survival levels (ie at very low radiation levels). This experiment can be handsomely and inexpensively accomodated in one of the existing underground laboratories.

  14. Ambient ultraviolet radiation levels in public shade settings.

    PubMed

    Moise, A F; Aynsley, R

    1999-11-01

    As people become better informed about the harmful effects of prolonged exposure to solar ultraviolet radiation (UVR, 280-400 nm) they will seek the protection of shade, particularly in tropical locations such as Townsville (19 degrees south). Using broad-band radiation sensors for solar ultraviolet-B (280-315 nm), ultraviolet-A (315-400 nm) and daylight (400-800 nm) radiation, the exposure levels were measured in both the horizontal (shaded and unshaded) and vertical (shaded and unshaded) directions. The measurements were conducted at eight locations (shade settings) in Townsville during the period between December 1997 (summer) and May 1998 (beginning of winter). The quality of protection was assessed by the ratio of unshaded to shaded radiation exposure, the UVB/shade protection ratio (UVB-SPR). The UVB-SPR varies considerably between the different shade settings, with a beach umbrella showing the least protection and dense foliage the highest protection. The roof of a house verandah can provide only little protection if the verandah catches the afternoon sun. Increasing cloud cover decreases the UVB-SPR for all settings because of the increase in the diffuse fraction of the radiation. Only one setting provided a UVB-SPR of 15 or higher, as suggested for protective shading against solar UVB radiation. Shade from direct sunlight alone does not provide enough protection against high levels of solar UVR. Apart from the transmission qualities of the shading material, it is the construction of the whole shade setting that determines the exposure levels underneath. A shade structure with enough overhang is recommended so that high levels of scattered radiation do not reach the skin.

  15. Tunnelling time in strong field ionisation

    NASA Astrophysics Data System (ADS)

    Landsman, Alexandra S.; Keller, Ursula

    2014-10-01

    We revisit the common approaches to tunnelling time in the context of attoclock experiments. These experiments measure tunnelling time using close-to-circularly polarised light of the infrared ultrashort laser pulse. We test the sensitivity of the attoclock measurements of tunnelling time to non-adiabatic effects, as described by a well-known theoretical model first developed by Perelomov, Popov, and Terent'ev. We find that in the case of ionisation of helium, both adiabatic and non-adiabatic theories give very similar predictions for ionisations times over a wide intensity range typical of ultrafast experiments.

  16. Lung cancer in relation to airborne radiation levels

    SciTech Connect

    Helsing, K.J.; Natta, P.V.; Comstock, G.W. ); Kalin, Heidi ) Chee, E. )

    1992-01-01

    A 1986 aeroradiometric survey of the eastern two-thirds of Washington County, Maryland provided and opportunity to study lung cancers in relation to gamma radiation levels. In the first approach, lung cancer deaths between 1963 and 1975 in four areas of the county categorized as low, moderately low, moderately high, and high showed relative risks of 1.00, 0.93, 1.01, and 1.43, respectively, after adjustment of sex, age, and smoking. A second approach used lung cancer cases diagnosed between 1975 and 1989, controls matched to cases by race, sex, and age, and aerometric radiation readings above the individual residences. In four levels of increasing gamma radiation, odds ratios adjusted for smoking were 1.00, 0.84, 0.90, and 0.92, respectively. No differences were statistically significant.

  17. Health effects of low level radiation: carcinogenesis, teratogenesis, and mutagenesis

    SciTech Connect

    Ritenour, E.R.

    1986-04-01

    The carcinogenic effects of radiation have been demonstrated at high dose levels. At low dose levels, such as those encountered in medical diagnosis, the magnitude of the effect is more difficult to quantify. Three reasons for this difficulty are (1) the effects in human populations are small compared with the natural incidence of cancer in the populations; (2) it is difficult to transfer results obtained in animal studies to the human experience; and (3) the effects of latency period and plateau increase the complexity of population studies. In spite of these difficulties, epidemiologic studies of human populations exposed to low levels of radiation still play a valuable role in the determination of radiation carcinogenecity. They serve to provide upper estimates of risk and to rule out the appearance of new effects that may be masked by the effects of high doses. While there is evidence for mutagenic effects of radiation in experimental animals, no conclusive human data exist at the present. It is not possible to rule out the presence of genetic effects of radiation in humans, however, because many problems exist with regard to the epidemiologic detection of small effects when the natural incidence is relatively large. In animals, subtle effects (eg, a decrease in the probability of survival from egg to adult) may occur with greater frequency than more dramatic disorders in irradiated populations. However, these types of genetic abnormalities are difficult to quantitate. Current risk estimates are based primarily upon data pertaining to dominant mutations in rodents. Some specific locus studies also permit identification of recessive mutation rates. The embryo and fetus are considered to be at greater risk for adverse effects of radiation than is the adult.

  18. Radiation efficiency of earthquake sources at different hierarchical levels

    SciTech Connect

    Kocharyan, G. G.

    2015-10-27

    Such factors as earthquake size and its mechanism define common trends in alteration of radiation efficiency. The macroscopic parameter that controls the efficiency of a seismic source is stiffness of fault or fracture. The regularities of this parameter alteration with scale define several hierarchical levels, within which earthquake characteristics obey different laws. Small variations of physical and mechanical properties of the fault principal slip zone can lead to dramatic differences both in the amplitude of released stress and in the amount of radiated energy.

  19. Resonance ionisation mass spectrometry of krypton and its applications in planetary science

    NASA Astrophysics Data System (ADS)

    Strashnov, I.; Gilmour, J. D.

    2014-06-01

    A new resonance ionisation time-of-flight mass spectrometer for determining krypton isotope ratios in extraterrestrial samples is presented. Laser heating is used to extract gas from mg-size samples. A cryogenic sample concentrator is employed. Atoms continuously condense on a 75 K stainless steel substrate at the back plate of a Wiley-McLaren laser ion source from where they are desorbed by a pulsed 1064 nm laser and resonantly ionized in the plume. A three-colour (116.5 nm, 558.1 nm and 1064 nm) excitation scheme is used. Tuneable coherent Vacuum Ultraviolet (vuv) radiation near 116.5 nm is generated by four-wave sum frequency mixing of 252.5 nm and 1507 nm pulsed dye laser beams in a binary mixture of negatively and positively dispersive gases (Xe and Ar). Isotope effects have been observed that reduce the reproducibility of isotope ratio measurements between odd-mass, non-zero nuclear spin isotopes and even-mass, zero nuclear spin isotopes. This can be minimised and stabilised by controlling the laser fluences, experimental geometry, and the population of the magnetic sub-levels of the excited atomic states used in the ionisation process. Once stability is achieved, sample-standard bracketing (during which the known isotope ratios of a standard are determined before and after the measurements of the sample under the same conditions) allows precision and reproducibility of 1 % for the major isotope ratios to be achieved in samples krypton atoms. Detection limits of atoms/isotope have been demonstrated, ratios of Kr in meteorites have been made with 5-10 % precision. Applications of the instrument in various areas of planetary science are also discussed.

  20. The contribution of interventional cardiology procedures to the population radiation dose in a 'health-care level I' representative region.

    PubMed

    Peruzzo Cornetto, Andrea; Aimonetto, Stefania; Pisano, Francesco; Giudice, Marcello; Sicuro, Marco; Meloni, Teodoro; Tofani, Santi

    2016-02-01

    This study evaluates per-procedure, collective and per capita effective dose to the population by interventional cardiology (IC) procedures performed during 2002-11 at the main hospital of Aosta Valley Region that can be considered as representative of the health-care level I countries, as defined by the UNSCEAR, based on its socio-demographic characteristics. IC procedures investigated were often multiple procedures in patients older than 60 y. The median extreme dose-area product values of 300 and 22 908 cGycm(2) were found for standard pacemaker implantation and coronary angioplasty, respectively, while the relative mean per-procedure effective dose ranged from 0.7 to 47 mSv. A 3-fold increase in frequency has been observed together with a correlated increase in the delivered per capita dose (0.05-0.27 mSv y(-1)) and the collective dose (5.8-35 man Sv y(-1)). Doses increased particularly from 2008 onwards mainly because of the introduction of coronary angioplasty procedures in the authors' institution. IC practice contributed remarkably in terms of effective dose to the population, delivering ∼10% of the total dose by medical ionising radiation examination categories.

  1. Radiative Lifetimes for High Levels of Neutral Fe

    NASA Astrophysics Data System (ADS)

    Lawler, James E.; Den Hartog, E.; Guzman, A.

    2013-01-01

    New radiative lifetime measurements for ~ 50 high lying levels of Fe I are reported. Laboratory astrophysics faces a challenge to provide basic spectroscopic data, especially reliable atomic transition probabilities, in the IR region for abundance studies. The availability of HgCdTe (HAWAII) detector arrays has opened IR spectral regions for extensive new spectroscopic studies. The SDSS III APOGEE project in the H-Band is an important example which will penetrate the dust obscuring the Galactic bulge. APOGEE will survey elemental abundances of 100,000 red giant stars in the bulge, bar, disk, and halo of the Milky Way. Many stellar spectra in the H-Band are, as expected, dominated by transitions of Fe I. Most of these IR transitions connect high levels of Fe. Our program has started an effort to meet this challenge with new radiative lifetime measurements on high lying levels of Fe I using time resolved laser induced fluorescence (TRLIF). The TRLIF method is typically accurate to 5% and is efficient. Our goal is to combine these accurate, absolute radiative lifetimes with emission branching fractions [1] to determine log(gf) values of the highest quality for Fe I lines in the UV, visible, and IR. This method was used very successfully by O’Brian et al. [2] on lower levels of Fe I. This method is still the best available for all but very simple spectra for which ab-initio theory is more accurate. Supported by NSF grant AST-0907732. [1] Branching fractions are being measured by M. Ruffoni and J. C. Pickering at Imperial College London. [2] O'Brian, T. R., Wickliffe, M. E., Lawler, J. E., Whaling, W., & Brault, J. W. 1991, J. Opt. Soc. Am. B 8, 1185

  2. Ultrasound Thermometry for Therapy-level Radiation Dosimetry

    NASA Astrophysics Data System (ADS)

    Taylor, Courtney

    2010-03-01

    Radiation oncology is the process of administering a specified dose of radiation to a patient currently receiving treatment for a form of cancer. In this process, it is vital to know the delivered dose for a given radiation beam to correctly treat a patient. The primary reference standard for absorbed dose is established using water calorimetry. The absorbed dose, typically of order 1 Gy (J/kg) at therapy levels, is realized by measuring sub-millikelvin temperature changes using a thermistor in a sensitive Wheatstone bridge. Ultrasound technology has been investigated as an alternative to thermistor measurements since the speed of sound propagation in water varies with temperature. With ultrasonic time-of-flight and highly sensitive phase detection techniques, temperature sensitivity comparable to that of the thermistor bridge has been achieved without introducing non-water materials into the test area. A single ultrasound transducer transmitting and receiving at 5.0 MHz throughout the length of the water phantom, and the phase change of the sound wave was used to determine temperature increase from an irradiative source at specified depths of the phantom. In this experiment, the exposure period was varied from 15s to 160s cyclically by modulating a heat lamp, and a profile of the measured temperature response as a function of the period was obtained using Fourier analysis. Due to the large temperature gradient in the water phantom, measurements are prone to convection which was indeed observed and will be discussed.

  3. Risk evaluation - conventional and low level effects of radiation

    SciTech Connect

    Bond, V.P.; Varma, M.N.

    1984-04-01

    Any discussion of the risk of exposure to potentially-hazardous agents in the environment inevitably involves the question of whether the dose effect curve is of the threshold or linear, non-threshold type. A principal objective of this presentation is to show that the function is actually two separate relationships, each representing distinctly different functions with differing variables on the axes, and each characteristic of quite different functions with differing variables on the axes, and each characteristic of quite different disciplines (i.e., the threshold function, of Pharmacology, Toxicology and Medicine (PTM); the linear, non-threshold function, of Public Health including safety and accident statistics (PHS)). It is shown that low-level exposure (LLE) to radiation falls clearly in the PHS category. A function for cell dose vs. the fraction of single cell quantal responses is characterized, which reflects the absolute and relative sensitivities of cells. Acceptance of this function would obviate any requirement for the use in Radiation Protection of the concepts of a standard radiation, Q, dose equivalent and rem. 9 references, 4 figures.

  4. 41 CFR 50-204.35 - Application for variations from radiation levels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... variations from radiation levels. 50-204.35 Section 50-204.35 Public Contracts and Property Management Other... FOR FEDERAL SUPPLY CONTRACTS Radiation Standards § 50-204.35 Application for variations from radiation levels. (a) In accordance with policy expressed in the Federal Radiation Council's memorandum...

  5. 41 CFR 50-204.35 - Application for variations from radiation levels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... variations from radiation levels. 50-204.35 Section 50-204.35 Public Contracts and Property Management Other... FOR FEDERAL SUPPLY CONTRACTS Radiation Standards § 50-204.35 Application for variations from radiation levels. (a) In accordance with policy expressed in the Federal Radiation Council's memorandum...

  6. 41 CFR 50-204.35 - Application for variations from radiation levels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... variations from radiation levels. 50-204.35 Section 50-204.35 Public Contracts and Property Management Other... FOR FEDERAL SUPPLY CONTRACTS Radiation Standards § 50-204.35 Application for variations from radiation levels. (a) In accordance with policy expressed in the Federal Radiation Council's memorandum...

  7. 41 CFR 50-204.35 - Application for variations from radiation levels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... variations from radiation levels. 50-204.35 Section 50-204.35 Public Contracts and Property Management Other... FOR FEDERAL SUPPLY CONTRACTS Radiation Standards § 50-204.35 Application for variations from radiation levels. (a) In accordance with policy expressed in the Federal Radiation Council's memorandum...

  8. 41 CFR 50-204.35 - Application for variations from radiation levels.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... variations from radiation levels. 50-204.35 Section 50-204.35 Public Contracts and Property Management Other... FOR FEDERAL SUPPLY CONTRACTS Radiation Standards § 50-204.35 Application for variations from radiation levels. (a) In accordance with policy expressed in the Federal Radiation Council's memorandum...

  9. Predicted ionisation in mitochondria and observed acute changes in the mitochondrial transcriptome after gamma irradiation: a Monte Carlo simulation and quantitative PCR study.

    PubMed

    Kam, Winnie Wai-Ying; McNamara, Aimee L; Lake, Vanessa; Banos, Connie; Davies, Justin B; Kuncic, Zdenka; Banati, Richard B

    2013-11-01

    It is a widely accepted that the cell nucleus is the primary site of radiation damage while extra-nuclear radiation effects are not yet systematically included into models of radiation damage. We performed Monte Carlo simulations assuming a spherical cell (diameter 11.5 μm) modelled after JURKAT cells with the inclusion of realistic elemental composition data based on published literature. The cell model consists of cytoplasm (density 1g/cm(3)), nucleus (diameter 8.5 μm; 40% of cell volume) as well as cylindrical mitochondria (diameter 1 μm; volume 0.5 μm(3)) of three different densities (1, 2 and 10 g/cm(3)) and total mitochondrial volume relative to the cell volume (10, 20, 30%). Our simulation predicts that if mitochondria take up more than 20% of a cell's volume, ionisation events will be the preferentially located in mitochondria rather than in the cell nucleus. Using quantitative polymerase chain reaction, we substantiate in JURKAT cells that human mitochondria respond to gamma radiation with early (within 30 min) differential changes in the expression levels of 18 mitochondrially encoded genes, whereby the number of regulated genes varies in a dose-dependent but non-linear pattern (10 Gy: 1 gene; 50 Gy: 5 genes; 100 Gy: 12 genes). The simulation data as well as the experimental observations suggest that current models of acute radiation effects, which largely focus on nuclear effects, might benefit from more systematic considerations of the early mitochondrial responses and how these may subsequently determine cell response to ionising radiation.

  10. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Effect of pulsed laser target cleaning on ionisation and acceleration of ions in a plasma produced by a femtosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Volkov, Roman V.; Vorobiev, A. A.; Gordienko, Vyacheslav M.; Dzhidzhoev, M. S.; Lachko, I. M.; Mar'in, B. V.; Savel'ev, Andrei B.; Uryupina, D. S.

    2005-10-01

    The impurity layer on the surface of a solid target is shown to exert a significant effect on the characteristics of the ion current of the laser plasma produced under the action of ultrahigh-intensity femtosecond radiation on the surface of this target. The application of pulsed laser cleaning gives rise to an additional high-energy component in the ion spectrum of the target material. It is shown that the ion current parameters of the laser plasma such as the average and highest ion charge, the highest ion energy of the target material, etc., can be controlled by varying the lead time of the cleaning laser radiation.

  11. Ionisation induced collapse of minihaloes

    NASA Astrophysics Data System (ADS)

    Back, Trevor

    2013-08-01

    In order to analyse the turbine blade life, the damage due to the combined thermal and mechanical loads should be adequately accounted for. This is more challenging when detailed component geometry is limited. Therefore, a compromise between the level of geometric detail and the complexity of the lifing method to be implemented would be necessary. This research focuses on how the life assessment of aero engine turbine blades can be done, considering the balance between available design inputs and adequate level of fidelity. Accordingly, the thesis contributes to developing a generic turbine blade lifing method that is based on the engine thermodynamic cycle; as well as integrating critical design/technological factors and operational parameters that influence the aero engine blade life. To this end, thermo-mechanical fatigue was identified as the critical damage phenomenon driving the life of the turbine blade.. The developed approach integrates software tools and numerical models created using the minimum design information typically available at the early design stages. Using finite element analysis of an idealised blade geometry, the approach captures relevant impacts of thermal gradients and thermal stresses that contribute to the thermo-mechanical fatigue damage on the gas turbine blade. The blade life is evaluated using the Neu/Sehitoglu thermo-mechanical fatigue model that considers damage accumulation due to fatigue, oxidation, and creep. The leading edge is examined as a critical part of the blade to estimate the damage severity for different design factors and operational parameters. The outputs of the research can be used to better understand how the environment and the operating conditions of the aircraft affect the

  12. What Is The Optimal Level of Solar Radiation Management?

    NASA Astrophysics Data System (ADS)

    Irvine, Peter; Ridgwell, Andy; Lunt, Dan

    2010-05-01

    Solar radiation management (SRM), achieved by stratospheric aerosol injections or by placing a sunshade in orbit, has the potential to cool the Earth's climate to pre-industrial temperatures even with large quantities of CO2 in the atmosphere. Many authors have observed that in such a geoengineered world there would be an undesirable reduction in the intensity of the hydrological cycle. With a large geoengineering intervention in the climate there are many known issues, and potentially some unexpected issues, which could arise as a result. If climate geoengineering is to be conducted, what is the optimal level of solar radiation management? Here we present the results from a set of experiments using the UK Met Office HadCM3L coupled GCM to simulate the effect of reductions in insolation on the climate of a world with four times the pre-industrial CO2 level. We consider 10 levels of SRM geoengineering from 100% application, returning global average temperature to pre-industrial levels, to 10% of this reduction in insolation. A pre-industrial control, two and four times pre-industrial CO2 experiments were also conducted. All the simulations were run for 400 years to allow the climate to reach a new equilibrium, with the last 100 years used for the climatological averages. In addition the Glimmer Ice Sheet model was used to simulate the viability of the Greenland ice sheet in each of these climates, the results of this section of the work are already published. We assess the effects of different levels of geoengineering on a high CO2 world by a number of different methods, including: temperature and precipitation changes and the stability of the Greenland Ice-Sheet. We include a measure of the change in the climate due solely to the geoengineering intervention, accounting for imperfect mitigation. We combine these variables to find a first estimate of the optimal level of solar radiation management for a high CO2 world. Global average temperature and precipitation

  13. Elevated blood lead levels from exposure via a radiator workshop.

    PubMed

    Treble, R G; Thompson, T S; Morton, D N

    1998-04-01

    Elevated lead levels were discovered in blood samples collected from family members where both the father and the mother worked in a radiator repair workshop. The father and mother were found to have blood lead levels of 2.0 and 0.5 mumol/L (41.7 and 10.4 micrograms/dL), respectively. The father's blood lead level was just below the Canadian occupational health and safety intervention level (2.5 mumol/L or 52.1 micrograms/dL). The two children had blood lead levels of 1.0 and 0.8 mumol/L (20.8 and 16.7 micrograms/dL), both of which are in excess of the recommended guideline for intervention in the case of children (0.5 mumol/L or 10.4 micrograms/dL). The exposure of the two children was possibly due to a combination of pathways including exposure at the workshop itself during visits and also the transportation of lead-containing dust to the home environment.

  14. Ionizing Radiation: The issue of radiation quality

    NASA Astrophysics Data System (ADS)

    Prise, Kevin; Schettino, Giuseppe

    Types of Ionising radiations are differentiated from each other by fundamental characteristics of their energy deposition patterns when they interact with biological materials. At the level of the DNA these non-random patterns drive differences in the yields and distributions of DNA damage patterns and specifically the production of clustered damage or complex lesions. The complex radiation fields found in space bring significant challenges for developing a mechanistic understanding of radiation effects from the perspective of radiation quality as these consist of a diverse range of particle and energy types unique to the space environment. Linear energy transfer, energy deposited per unit track length in units of keV per micron, has long been used as a comparator for different types of radiation but has limitations in that it is an average value. Difference in primary core ionizations relative to secondary delta ray ranges vary significantly with particle mass and energy leading to complex interrelationships with damage production at the cellular level. At the cellular level a greater mechanistic understanding is necessary, linking energy deposition patterns to DNA damage patterns and cellular response, to build appropriate biophysical models that are predictive for different radiation qualities and mixed field exposures. Defined studies using monoenergetic beams delivered under controlled conditions are building quantitative data sets of both initial and long term changes in cells as a basis for a great mechanistic understanding of radiation quality effects of relevance to not only space exposures but clinical application of ion-beams.

  15. Radiation-induced taste aversion: effects of radiation exposure level and the exposure-taste interval

    SciTech Connect

    Spector, A.C.; Smith, J.C.; Hollander, G.R.

    1986-05-01

    Radiation-induced taste aversion has been suggested to possibly play a role in the dietary difficulties observed in some radiotherapy patients. In rats, these aversions can still be formed even when the radiation exposure precedes the taste experience by several hours. This study was conducted to examine whether increasing the radiation exposure level could extend the range of the exposure-taste interval that would still support the formation of a taste aversion. Separate groups of rats received either a 100 or 300 R gamma-ray exposure followed 1, 3, 6, or 24 h later by a 10-min saccharin (0.1% w/v) presentation. A control group received a sham exposure followed 1 h later by a 10-min saccharin presentation. Twenty-four hours following the saccharin presentation all rats received a series of twelve 23-h two-bottle preference tests between saccharin and water. The results indicated that the duration of the exposure-taste interval plays an increasingly more important role in determining the initial extent of the aversion as the dose decreases. The course of recovery from taste aversion seems more affected by dose than by the temporal parameters of the conditioning trial.

  16. Deep levels and radiation effects in p-InP

    NASA Technical Reports Server (NTRS)

    Anderson, W. A.; Singh, A.; Jiao, K.; Lee, B.

    1989-01-01

    A survey was conducted on past studies of hole traps in InP. An experiment was designed to evaluate hole traps in Zn-doped InP after fabrication, after electron irradiation and after annealing using deep level transient spectroscopy. Data similar to that of Yamaguchi was seen with observation of both radiation-induced hole and electron traps at E sub A=0.45 eV and 0.03 eV, respectively. Both traps are altered by annealing. It is also shown that trap parameters for surface-barrier devices are influenced by many factors such as bias voltage, which probes traps at different depths below the surface. These devices require great care in data evaluation.

  17. Low Level Laser Therapy: laser radiation absorption in biological tissues

    NASA Astrophysics Data System (ADS)

    Di Giacomo, Paola; Orlando, Stefano; Dell'Ariccia, Marco; Brandimarte, Bruno

    2013-07-01

    In this paper we report the results of an experimental study in which we have measured the transmitted laser radiation through dead biological tissues of various animals (chicken, adult and young bovine, pig) in order to evaluate the maximum thickness through which the power density could still produce a reparative cellular effect. In our experiments we have utilized a pulsed laser IRL1 ISO model (based on an infrared diode GaAs, λ=904 nm) produced by BIOMEDICA s.r.l. commonly used in Low Level Laser Therapy. Some of the laser characteristics have been accurately studied and reported in this paper. The transmission results suggest that even with tissue thicknesses of several centimeters the power density is still sufficient to produce a cell reparative effect.

  18. Influence of low-level laser radiation on kidney functions

    NASA Astrophysics Data System (ADS)

    Koultchavenia, Ekaterina V.

    1998-12-01

    Most of all renal diseases are accompanied by lowering of kidney functions. That makes the quality of the treatment worse. On an example 69 patients receiving Low-Level Laser Therapy (LLLT), the influence of the laser radiation on a contracting system of blood, on current of an active and inactive tubercular inflammation and on partial functions of kidneys were investigated. Is established, that LLLT does not render influence to a contracting system; promotes stopping of unspecific and moderate peaking of a specific inflammation of kidneys. Is proved, that after a rate of laserotherapy the improving of a blood micricirculation in kidney occurs in 57.9% of patients; a secretion - in 63.1% of the patients; a stimulation of urodynamic is fixed in 79% of cases. Magnification of diuresis, improving filtration and concentration functions of kidneys also is marked.

  19. Correcting spaceborne reflectivity measurements for application in solar ultraviolet radiation levels calculations at ground level

    NASA Astrophysics Data System (ADS)

    den Outer, P. N.; van Dijk, A.; Slaper, H.; Lindfors, A. V.; de Backer, H.; Bais, A. F.; Feister, U.; Koskela, T.; Josefsson, W.

    2012-01-01

    The Lambertian Equivalent Reflection (LER) produced by satellite-carried instruments is used to determine cloud effects on ground level UltraViolet (UV) radiation. The focus is on data use from consecutive operating instruments: the Total Ozone Mapping Spectrometers (TOMS) flown on Nimbus 7 from 1979 to 1992, TOMS on Earth Probe from 1996 to 2005, and the Ozone Monitoring Instrument (OMI) flown on Aura since 2004. The LER data produced by TOMS on Earth Probe is only included until 2002. The possibility to use the Radiative Cloud Fraction (RCF)-product of OMI is also investigated. A comparison is made with cloud effects inferred from ground-based pyranometer measurements at over 83 World Radiation Data Centre stations. Modelled UV irradiances utilizing LER data are compared with measurements of UV irradiances at eight European low elevation stations. The LER data set of the two TOMS instruments shows a consistent agreement, and the required corrections are of low percentage i.e. 2-3%. In contrast, the LER data of OMI requires correction of 7-10%, and a solar angle dependency therein is more pronounced. These corrections were inferred from a comparison with pyranometer data, and tested using the UV measurements. The RCF product of OMI requires a large correction but can then be implemented as a cloud effect proxy. However, a major drawback of RCF is the large number of clipped data, i.e. 18%, and results are not better than those obtained with the corrected LER product of OMI. The average reduction of UV radiation due to clouds for all sites together indicate a small trend: a diminishing cloudiness, in line with ground-based UV observations. Uncorrected implementation of LER would have indicated the opposite. An optimal field of view of 1.25° was established for LER data to calculate UV radiations levels. The corresponding area can be traversed within 5-7 h at the average wind speeds found for the West European continent.

  20. The Australasian Radiation Protection Society's position statement on risks from low levels of ionizing radiation.

    PubMed

    Higson, Donald

    2007-09-30

    Controversy continues on whether or not ionizing radiation is harmful at low doses, with unresolved scientific uncertainty about effects below a few tens of millisieverts. To settle what regulatory controls should apply in this dose region, an assumption has to be made relating dose to the possibility of harm or benefit. The position of the Australasian Radiation Protection Society on this matter is set out in a statement adopted by the Society in 2005. Its salient features are: --There is insufficient evidence to establish a dose-effect relationship for doses that are less than a few tens of millisieverts in a year. A linear extrapolation from higher dose levels should be assumed only for the purpose of applying regulatory controls.--Estimates of collective dose arising from individual doses that are less than some tens of millisieverts in a year should not be used to predict numbers of fatal cancers. --The risk to an individual of doses significantly less than 100 microsieverts in a year is so small, if it exists at all, that regulatory requirements to control exposure at this level are not warranted.

  1. 49 CFR 173.441 - Radiation level limitations and exclusive use provisions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Radiation level limitations and exclusive use... Radiation level limitations and exclusive use provisions. (a) Except as provided in paragraph (b) of this... prepared for shipment, so that under conditions normally incident to transportation, the radiation...

  2. 49 CFR 173.441 - Radiation level limitations and exclusive use provisions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Radiation level limitations and exclusive use... Radiation level limitations and exclusive use provisions. (a) Except as provided in paragraph (b) of this... prepared for shipment, so that under conditions normally incident to transportation, the radiation...

  3. 49 CFR 173.441 - Radiation level limitations and exclusive use provisions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Radiation level limitations and exclusive use... Radiation level limitations and exclusive use provisions. (a) Except as provided in paragraph (b) of this... prepared for shipment, so that under conditions normally incident to transportation, the radiation...

  4. 10 CFR 34.21 - Limits on external radiation levels from storage containers and source changers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Limits on external radiation levels from storage... INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Equipment § 34.21 Limits on external radiation levels from storage containers and source changers. The...

  5. 10 CFR 34.21 - Limits on external radiation levels from storage containers and source changers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Limits on external radiation levels from storage... INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Equipment § 34.21 Limits on external radiation levels from storage containers and source changers. The...

  6. 49 CFR 173.441 - Radiation level limitations and exclusive use provisions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Radiation level limitations and exclusive use... Radiation level limitations and exclusive use provisions. (a) Except as provided in paragraph (b) of this... prepared for shipment, so that under conditions normally incident to transportation, the radiation...

  7. 10 CFR 34.21 - Limits on external radiation levels from storage containers and source changers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Limits on external radiation levels from storage... INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Equipment § 34.21 Limits on external radiation levels from storage containers and source changers. The...

  8. 10 CFR 34.21 - Limits on external radiation levels from storage containers and source changers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Limits on external radiation levels from storage... INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Equipment § 34.21 Limits on external radiation levels from storage containers and source changers. The...

  9. 10 CFR 34.21 - Limits on external radiation levels from storage containers and source changers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Limits on external radiation levels from storage... INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Equipment § 34.21 Limits on external radiation levels from storage containers and source changers. The...

  10. 49 CFR 173.441 - Radiation level limitations and exclusive use provisions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Radiation level limitations and exclusive use... Radiation level limitations and exclusive use provisions. (a) Except as provided in paragraph (b) of this... prepared for shipment, so that under conditions normally incident to transportation, the radiation...

  11. The use of particle beam mass spectrometry for the measurement of impurities in a nabumetone drug substance, not easily amenable to atmospheric pressure ionisation techniques.

    PubMed

    Wolff, J C; Hawtin, P N; Monté, S; Balogh, M; Jones, T

    2001-01-01

    Liquid chromatography/particle beam mass spectrometry (LC/PB-MS) was used for the structural elucidation of some impurities in nabumetone as this compound poorly ionises by atmospheric pressure ionisation (API) techniques. PB-MS was optimised for nabumetone and a sensitivity study was carried out. To obtain full scan electron ionisation spectra a minimum of 100 ng of compound on column was needed. By using 20 mg/mL solutions of nabumetone, impurities at levels of about 250 ppm mass fraction relative to nabumetone could be detected. Results were compared with LC/API-MS and previous GC/MS.

  12. Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets

    NASA Astrophysics Data System (ADS)

    Helling, Ch; Rimmer, P. B.; Rodriguez-Barrera, I. M.; Wood, Kenneth; Robertson, G. B.; Stark, C. R.

    2016-07-01

    Brown dwarfs and giant gas extrasolar planets have cold atmospheres with rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes and material composition, vary with height, and the mineral cloud particles are charged due to triboelectric processes in such dynamic atmospheres. The dynamics of the atmospheric gas is driven by the irradiating host star and/or by the rotation of the objects that changes during its lifetime. Thermal gas ionisation in these ultra-cool but dense atmospheres allows electrostatic interactions and magnetic coupling of a substantial atmosphere volume. Combined with a strong magnetic field \\gg {{B}\\text{Earth}} , a chromosphere and aurorae might form as suggested by radio and x-ray observations of brown dwarfs. Non-equilibrium processes like cosmic ray ionisation and discharge processes in clouds will increase the local pool of free electrons in the gas. Cosmic rays and lighting discharges also alter the composition of the local atmospheric gas such that tracer molecules might be identified. Cosmic rays affect the atmosphere through air showers in a certain volume which was modelled with a 3D Monte Carlo radiative transfer code to be able to visualise their spacial extent. Given a certain degree of thermal ionisation of the atmospheric gas, we suggest that electron attachment to charge mineral cloud particles is too inefficient to cause an electrostatic disruption of the cloud particles. Cloud particles will therefore not be destroyed by Coulomb explosion for the local temperature in the collisional dominated brown dwarf and giant gas planet atmospheres. However, the cloud particles are destroyed electrostatically in regions with strong gas ionisation. The potential size of such cloud holes would, however, be too small and might occur too far inside the cloud to mimic the effect of, e.g. magnetic field induced star spots.

  13. 28 CFR 79.44 - Proof of working level month exposure to radiation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... radiation. 79.44 Section 79.44 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) CLAIMS UNDER THE RADIATION EXPOSURE COMPENSATION ACT Eligibility Criteria for Claims by Uranium Miners § 79.44 Proof of working level month exposure to radiation. (a) If one or more of the sources in § 79.43(a) contain...

  14. 28 CFR 79.44 - Proof of working level month exposure to radiation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... radiation. 79.44 Section 79.44 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) CLAIMS UNDER THE RADIATION EXPOSURE COMPENSATION ACT Eligibility Criteria for Claims by Uranium Miners § 79.44 Proof of working level month exposure to radiation. (a) If one or more of the sources in § 79.43(a) contain...

  15. 28 CFR 79.44 - Proof of working level month exposure to radiation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... radiation. 79.44 Section 79.44 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) CLAIMS UNDER THE RADIATION EXPOSURE COMPENSATION ACT Eligibility Criteria for Claims by Uranium Miners § 79.44 Proof of working level month exposure to radiation. (a) If one or more of the sources in § 79.43(a) contain...

  16. 28 CFR 79.44 - Proof of working level month exposure to radiation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... radiation. 79.44 Section 79.44 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) CLAIMS UNDER THE RADIATION EXPOSURE COMPENSATION ACT Eligibility Criteria for Claims by Uranium Miners § 79.44 Proof of working level month exposure to radiation. (a) If one or more of the sources in § 79.43(a) contain...

  17. 28 CFR 79.44 - Proof of working level month exposure to radiation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... radiation. 79.44 Section 79.44 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) CLAIMS UNDER THE RADIATION EXPOSURE COMPENSATION ACT Eligibility Criteria for Claims by Uranium Miners § 79.44 Proof of working level month exposure to radiation. (a) If one or more of the sources in § 79.43(a) contain...

  18. Derivation of the radiation budget at ground level from satellite measurements

    NASA Technical Reports Server (NTRS)

    Raschke, E.

    1982-01-01

    Determination of the Earth radiaton budget and progress in measurement of the budget components and in the treatment of imaging data from satellites are described. Methods for calculating the radiation budget in a general circulation model, radiative transfer characteristics of clouds, computation of solar radiation at ground level using meteorological data and development of a 10-channel radiometer are discussed.

  19. Derivatisation and gas chromatography-chemical ionisation mass spectrometry of selected synthetic and natural endocrine disruptive chemicals.

    PubMed

    Lerch, Oliver; Zinn, Peter

    2003-03-28

    Methods for ultra trace detection of endocrine disruptive chemicals (EDCs) are needed because of their low levels of impact. Twenty-one EDCs were selected, including 17beta-estradiol, 17alpha-ethinylestradiol, 17beta-testosterone and bisphenol A. Derivatisation with eight different fluorine containing compounds was examined. All EDCs could be derivatised automatedly (autosampler) with heptafluorobutyric acid (HFB) anhydride and trifluoroacetic acid (TFA) anhydride, respectively. The detection of these HFB and TFA derivatives in different chemical ionisation modes was studied. Fourteen different reagent gases, including methane, ammonia, acetone and water, were tested with the HFB and TFA derivatives in the negative chemical ionisation mode. Furthermore both types of derivatives were measured in positive chemical ionisation mode. Methane or water provide a good detection of all 21 TFA derivatives and create mass spectra with few fragmentation and characteristic mass peaks. This could serve as a basis for tandem or multiple mass spectrometric measurements.

  20. Is copper-silver ionisation safe and effective in controlling legionella?

    PubMed

    Cachafeiro, S Perez; Naveira, I Mato; García, I González

    2007-11-01

    Copper-silver ionisation is gaining popularity worldwide as a water disinfection method. We review the literature that supports the effectiveness and safety of the copper-silver ionisation pertaining to legionella control in water distribution systems. A search between January 1997 and January 2007 was conducted in relevant health databases: Medline, Embase, NHS CRD, Cochrane Library Plus, Web of Knowledge, IME (Spanish Medical Index) and IBECS (Health Sciences Bibliographic Index). Ten published studies were selected according to inclusion and exclusion criteria previously established; most of these were experimental. Legionella levels decrease with the application of any of the procedures used in these studies and the procedures can be combined to obtain better outcomes. No studies containing an economic evaluation were found. We conclude that copper-silver ionisation is an effective method to control legionella, bearing in mind that eradication cannot be achieved by any method in isolation. Maintaining high temperatures in the water system can maximise effectiveness of the method. Copper-silver appears to be safe, as long as ion levels are monitored and kept within international recommended levels. More studies with concurrent control group, long follow-up and economic evaluation are required to properly assess this procedure.

  1. New techniques of low level environmental radiation monitoring at JLab

    SciTech Connect

    P. Degtiarenko, V. Popov

    2010-07-01

    We present the first long-term environmental radiation monitoring results obtained using the technique of pulse mode readout for the industry-standard Reuter-Stokes RSS-1013 argon-filled high pressure ionization chambers (HPIC). With novel designs for the front-end electronics readout and customized signal processing algorithms, we are capable of detecting individual events of gas ionization in the HPIC, caused by interactions of gammas and charged particles in the gas. The technique provides enough spectroscopic information to distinguish between several different types of environmental and man-made radiation. The technique also achieves a high degree of sensitivity and stability of the data, allowing long-term environmental radiation monitoring with unprecedented precision.

  2. Low-level radiation effects on immune cells

    SciTech Connect

    Makinodan, T.

    1995-12-31

    The purpose of this study was to characterize the effects of chronic low-dose ionizing radiation (LDR) on murine immune cells. Previously, it had been reported that LDR enhances the proliferative activity of T cells in vitro and delays the growth of transplantable immunogenic tumors in vivo. This suggests that LDR eliminates immune suppressor cells, which downregulates immune response and/or adoptively upregulates the responsiveness of immune effector cells. It had also been reported that human lymphocytes become refractive to high dose radiation-induced chromosomal aberrations by pretreating mitotically active lymphocytes in vitro with very low doses of ionizing radiation, and the adaptive effect can be abrogated by cycloheximide. This suggests that protein synthesis is required for lymphocytes to respond adoptively to LDR.

  3. Cosmic radiation in commercial aviation.

    PubMed

    Bagshaw, Michael

    2008-05-01

    This paper reviews the current knowledge of cosmic radiation and its applicability to commercial aviation. Galactic cosmic radiation emanates from outside the solar system, while occasionally a disturbance in the suns' atmosphere leads to a surge in radiation particles. Protection is provided by the suns' magnetic field, the earths' magnetic field, and the earths' atmosphere. Dose rates are dependent on the altitude, the geomagnetic latitude and the solar cycle. For occupational exposure to ionising radiation, which includes aircrew, the International Commission on Radiological Protection recommends maximum mean body effective dose limits of 20mSv/yr (averaged over 5 years, with a maximum in any 1 year of 50mSv). Radiation doses can be measured during flight or may be calculated using a computer-modelling program such as CARI, EPCARD, SIEVERT or PCAIRE. Mean ambient equivalent dose rates are consistently reported in the region of 4-5microSv/h for long-haul pilots and 1-3microSv/h for short-haul, giving an annual mean effective exposure of the order 2-3mSv for long-haul and 1-2mSv for short-haul pilots. Epidemiological studies of flight crew have not shown conclusive evidence for any increase in cancer mortality or cancer incidence directly attributable to ionising radiation exposure. Whilst there is no level of radiation exposure below which effects do not occur, current evidence indicates that the probability of airline crew or passengers suffering adverse health effects as a result of exposure to cosmic radiation is very low.

  4. Photosensitizing potential of ciprofloxacin at ambient level of UV radiation.

    PubMed

    Agrawal, Neeraj; Ray, Ratan Singh; Farooq, Mohammad; Pant, Aditya Bhushan; Hans, Rajendra Kumar

    2007-01-01

    Ciprofloxacin is a widely used fluoroquinolone drug with broad spectrum antibacterial activities. Clinical experience has shown incidences of adverse effects related to skin, hepatic, central nervous system, gastrointestinal and phototoxicity. India is a tropical country and sunlight is abundant throughout the day. In this scenario exposure to ambient levels of ultraviolet radiation (UV-R) in sunlight may lead to harmful effects in ciprofloxacin users. Phototoxicity assessment of ciprofloxacin was studied by two mouse fibroblast cell lines L-929 and NIH-3T3. Generation of reactive oxygen species (ROS) like singlet oxygen (1O2), superoxide anion radical (O2*-) and hydroxyl radical (*OH) was studied under the exposure of ambient intensities of UV-A (1.14, 1.6 and 2.2 mW cm(-2)), UV-B (0.6, 0.9 and 1.2 mW cm(-2)) and sunlight (60 min). The drug was generating 1O2, O2*- and *OH in a concentration and dose-dependent manner. Sodium azide (NaN3) and 1,4-diazabicyclo 2-2-2-octane (DABCO) inhibited the generation of 1O2. Superoxide dismutase (SOD) inhibited 90-95% O2*- generation. The drug (5-40 microg mL(-1)) was responsible for linoleic acid peroxidation. Quenching study of linoleic acid peroxidation with SOD (25 and 50 U mL(-1)) confirms the involvement of ROS in drug-induced lipid peroxidation. The generation of *OH radical was further confirmed by using specific quenchers of *OH such as mannitol (0.5 M) and sodium benzoate (0.5 M). 2'-deoxyguanosine (2'-dGuO) assay and linoleic acid peroxidation showed that ROS were mainly responsible for ciprofloxacin-sensitized photo-degradation of guanine base. L-929 cell line showed 29%, 34% and 54% reduced cell viability at higher drug concentration (300 microg mL(-1)) under UV-A, UV-B and sunlight, respectively. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay in NIH-3T3 cell line at higher drug concentration (300 microg mL(-1)) showed a decrease in cell viability by 54%, 56% and 59% under UV-A, UV

  5. Radiation levels in cyclotron-radiochemistry facility measured by a novel comprehensive computerized monitoring system

    NASA Astrophysics Data System (ADS)

    Mishani, E.; Lifshits, N.; Osavistky, A.; Kaufman, J.; Ankry, N.; Tal, N.; Chisin, R.

    1999-04-01

    Radiation levels in a cyclotron-radiochemistry facility were measured during the production of commonly used PET radiopharmaceuticals by a comprehensive computerized monitoring system. The system consists of three major components: on-line radiation monitoring channels, an area control unit, and a gas waste management unit. During production the radiation levels were measured in the cyclotron vault, inside automatic chemistry production and research shielded cells, in the radiochemistry room, in the gas waste decay tank, in the chimney filters, and at the top of the cells chimney. Each detector was calibrated in a known radiation field, and a special detector dead time correction was performed in order to achieve detected signal-to-radiation linearity for the Geiger tubes located in the radiochemistry production and research cells. During production of C-11 and O-15 PET radiopharmaceuticals, high radiation levels were measured in the gas waste decay tank (240 and 80 mR/h, respectively). In contrast, the radiation levels at the chimney filters and at the top of the cells chimney did not exceed the International Atomic Energy Agency (IAEA) Drive Air Concentration (DAC) recommended for C-11 or O-15. During production of FDG, high radiation levels were measured at the chimney filters, however the radiation level at the top of the chimney (3.7 μCi/m 3) did not exceed the F-18 DAC recommendation (27 μCi/m 3). Low radiation levels of approximately 0.5-1 mR/h were measured in the radiochemistry room during production of PET radiopharmaceuticals. In the cyclotron vault, 2 min after bombardment the radiation levels at 2 m from the cyclotron decreased to 1-2 mR/h. The addition of a gas waste decay system to computerized monitoring channels located near each strategic point of the site allows for a comprehensive survey of the radiochemical processes.

  6. A theoretical concept of low level/low LET radiation carcinogenic risk (LLCR) projection

    SciTech Connect

    Filyushkin, I.V.

    1992-06-01

    Carcinogenic risk to humans resulting from low level/low LET radiation exposure (LLLCR) has not been observed directly because epidemiological observations have not yet provided statistically significant data on risk values. However, these values are of great interest for radiation health science and radiation protection practice under both normal conditions and emergency situations. This report presents a theoretical contribution to the validation of dose and dose rate efficiency factors (DDREF) transforming cocinogenic risk coefficients from those revealed in A-bomb survivors to factors appropriate for the projection of the risk resulting from very low levels of low LET radiation.

  7. Resistance of Feather-Associated Bacteria to Intermediate Levels of Ionizing Radiation near Chernobyl.

    PubMed

    Ruiz-González, Mario Xavier; Czirják, Gábor Árpád; Genevaux, Pierre; Møller, Anders Pape; Mousseau, Timothy Alexander; Heeb, Philipp

    2016-03-15

    Ionizing radiation has been shown to produce negative effects on organisms, although little is known about its ecological and evolutionary effects. As a study model, we isolated bacteria associated with feathers from barn swallows Hirundo rustica from three study areas around Chernobyl differing in background ionizing radiation levels and one control study site in Denmark. Each bacterial community was exposed to four different γ radiation doses ranging from 0.46 to 3.96 kGy to test whether chronic exposure to radiation had selected for resistant bacterial strains. Experimental radiation duration had an increasingly overall negative effect on the survival of all bacterial communities. After exposure to γ radiation, bacteria isolated from the site with intermediate background radiation levels survived better and produced more colonies than the bacterial communities from other study sites with higher or lower background radiation levels. Long-term effects of radiation in natural populations might be an important selective pressure on traits of bacteria that facilitate survival in certain environments. Our findings indicate the importance of further studies to understand the proximate mechanisms acting to buffer the negative effects of ionizing radiation in natural populations.

  8. Resistance of Feather-Associated Bacteria to Intermediate Levels of Ionizing Radiation near Chernobyl

    PubMed Central

    Ruiz-González, Mario Xavier; Czirják, Gábor Árpád; Genevaux, Pierre; Møller, Anders Pape; Mousseau, Timothy Alexander; Heeb, Philipp

    2016-01-01

    Ionizing radiation has been shown to produce negative effects on organisms, although little is known about its ecological and evolutionary effects. As a study model, we isolated bacteria associated with feathers from barn swallows Hirundo rustica from three study areas around Chernobyl differing in background ionizing radiation levels and one control study site in Denmark. Each bacterial community was exposed to four different γ radiation doses ranging from 0.46 to 3.96 kGy to test whether chronic exposure to radiation had selected for resistant bacterial strains. Experimental radiation duration had an increasingly overall negative effect on the survival of all bacterial communities. After exposure to γ radiation, bacteria isolated from the site with intermediate background radiation levels survived better and produced more colonies than the bacterial communities from other study sites with higher or lower background radiation levels. Long-term effects of radiation in natural populations might be an important selective pressure on traits of bacteria that facilitate survival in certain environments. Our findings indicate the importance of further studies to understand the proximate mechanisms acting to buffer the negative effects of ionizing radiation in natural populations. PMID:26976674

  9. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: On the bifurcation of the circular polarisation of the fifth and seventh pump-field harmonics generated in the plasma produced by the ionisation of a gas of excited hydrogen-like atoms

    NASA Astrophysics Data System (ADS)

    Silin, Viktor P.; Silin, Pavel V.

    2006-05-01

    Within the framework of the Bethe ionisation model we considered theoretically the dependences of the degree of circular polarisation of the fifth and seventh pump-field harmonics, which are generated due to bremsstrahlung, on the electric intensity of the pump field, the degree of its circular polarisation, and the principal quantum number of the excited states of hydrogen-like atoms of a gas ionised by the pump field. A bifurcation of the circular polarisation of these harmonics was discovered, which confirms our previous hypothesis that this effect is common for harmonics generated due to the bremsstrahlung in the pump field when the plasma electrons oscillate in this field. We determined how the relationships under consideration are scaled with VEn/VZ, the product of electron oscillation velocity and the principal quantum number of the excited electron divided by the Coulomb velocity.

  10. Surface solar ultraviolet radiation for paleoatmospheric levels of oxygen and ozone

    NASA Technical Reports Server (NTRS)

    Levine, J. S.

    1980-01-01

    Many investigators have concluded that the level of solar ultraviolet radiation (200-300 nm) reaching the surface was a key parameter in the origin and evolution of life on earth. The level of solar ultraviolet radiation between 200 and 300 nm is controlled primarily by molecular absorption by ozone, whose presence is strongly coupled to the level of molecular oxygen. In this paper, a series of calculations is presented of the solar ultraviolet radiation reaching the surface for oxygen levels ranging from 0.0001 the present atmospheric level to the present level. The solar spectrum between 200 and 300 nm has been divided into 34 spectral intervals. For each spectral interval, the solar ultraviolet radiation reaching the earth's surface has been calculated by considering the attenuation of the incoming beam due to ozone and oxygen absorption. A one-dimensional photochemical model of the atmosphere was used for these calculations.

  11. Cosmic-ray ionisation of dense molecular clouds

    NASA Astrophysics Data System (ADS)

    Vaupre, Solenn

    2015-07-01

    Cosmic rays (CR) are of tremendous importance in the dynamical and chemical evolution of interstellar molecular clouds, where stars and planets form. CRs are likely accelerated in the shells of supernova remnants (SNR), thus molecular clouds nearby can be irradiated by intense fluxes of CRs. CR protons have two major effects on dense molecular clouds: 1) when they encounter the dense medium, high-energy protons (>280 MeV) create pions that decay into gamma-rays. This process makes SNR-molecular cloud associations intense GeV and/or TeV sources whose spectra mimic the CR spectrum. 2) at lower energies, CRs penetrate the cloud and ionise the gas, leading to the formation of molecular species characteristic of the presence of CRs, called tracers of the ionisation. Studying these tracers gives information on low-energy CRs that are unaccessible to any other observations. I studied the CR ionisation of molecular clouds next to three SNRs: W28, W51C and W44. These SNRs are known to be interacting with the nearby clouds, from the presence of shocked gas, OH masers and pion-decay induced gamma-ray emission. My work includes millimeter observations and chemical modeling of tracers of the ionisation in these dense molecular clouds. In these three regions, we determined an enhanced CR ionisation rate, supporting the hypothesis of an origin of the CRs in the SNR nearby. The evolution of the CR ionisation rate with the distance to the SNR brings valuable constraints on the propagation properties of low-energy CRs. The method used relies on observations of the molecular ions HCO+ and DCO+, which shows crucial limitations at high ionisation. Therefore, I investigated, both through modeling and observations, the chemical abundances of several other species to try and identity alternative tracers of the ionisation. In particular, in the W44 region, observations of N2H+ bring additional constraints on the physical conditions, volatile abundances in the cloud, and the ionisation

  12. Health effects of low-level radiation in shipyard workers. Final report: [Draft

    SciTech Connect

    Matanoski, G.M.

    1991-06-01

    The Nuclear Shipyard Workers Study (NSWS) was designed to determine whether there is an excess risk of leukemia or other cancers associated with exposure to low levels of gamma radiation. The study compares the mortality experience of shipyard workers who qualified to work in radiation areas to the mortality of similar workers who hold the same types of jobs but who are not authorized to work in radiation areas. The population consists of workers from six government and two private shipyards.

  13. The measurement of radiation levels in Australian zircon milling plants.

    PubMed

    Hartley, B M

    2001-01-01

    The processing of zircon often involves grinding it to a fine powder known as zircon flour. As the resulting particles are small they may be inhaled if they become airborne and, since they contain some uranium and thorium, deliver radiation doses to workers. Theoretical estimates and measured radiation exposure in Australian zircon milling plants are reported in this paper. Theoretical doses, calculated in this work, indicate a potential maximum dose to workers of 5.5 mSv y(-1). Measured doses, based on normal work practices, vary in different plants from 0.66 mSv to 1.03 mSv y(-1) and suggest that in the dustiest Australian zircon milling plants the maximum dose would be of the order of 1 mSv y(-1). Measurements, which focused on the dustiest operations, indicate an upper limit of dose of about 3 mSv y(-1). Based on the theoretical and measured doses not exceeding 6 mSv y(-1), workers would not be designated as Category A workers, and probably would not be designated Category B workers, exceeding 1 mSv y(-1), under the guidelines of a EURATOM Directive.

  14. Jupiter radiation test levels and their expected impact on an encounter mission

    NASA Technical Reports Server (NTRS)

    Barengoltz, J. B.

    1972-01-01

    The upper limit, of electron and proton fluences for a thermoelectric outer planet spacecraft mission in a near-Jupiter environment, for use as radiation design restraints, were extracted from a model of the Jovian trapped radiation belts. Considerations of radiation effects in semiconductor devices were employed to construct simplified radiation test levels based on the design restraints. Corresponding levels, based on the nominal belt models, are one to three orders of magnitude smaller. In terms of expected radiation-induced degradation in semiconductor devices, an encounter with an environment as severe as the design restraints would require hardening the system in order to guarantee high reliability. On the other hand, the nominal levels would only necessitate care in the selection of components and the avoidance of certain semiconductor components.

  15. Ambient radiation levels in positron emission tomography/computed tomography (PET/CT) imaging center

    PubMed Central

    Santana, Priscila do Carmo; de Oliveira, Paulo Marcio Campos; Mamede, Marcelo; Silveira, Mariana de Castro; Aguiar, Polyanna; Real, Raphaela Vila; da Silva, Teógenes Augusto

    2015-01-01

    Objective To evaluate the level of ambient radiation in a PET/CT center. Materials and Methods Previously selected and calibrated TLD-100H thermoluminescent dosimeters were utilized to measure room radiation levels. During 32 days, the detectors were placed in several strategically selected points inside the PET/CT center and in adjacent buildings. After the exposure period the dosimeters were collected and processed to determine the radiation level. Results In none of the points selected for measurements the values exceeded the radiation dose threshold for controlled area (5 mSv/year) or free area (0.5 mSv/year) as recommended by the Brazilian regulations. Conclusion In the present study the authors demonstrated that the whole shielding system is appropriate and, consequently, the workers are exposed to doses below the threshold established by Brazilian standards, provided the radiation protection standards are followed. PMID:25798004

  16. Base Level Management of Radio Frequency Radiation Protection Program

    DTIC Science & Technology

    1989-04-01

    with a healti h....:d. V. STANDARDS A. The Basis of Our Permissible Exposure Limits (PELs). 1. What level of RFR is safe? It’s a big question, and a lot...mobile lifting equipment, hand-held radios, climbing gear, etc. b. Check out your equipment. Is the calibration current? Does the probe frequency range...CH--Hazardous levels possible, but only in areas that require climbing . GH--Ground-level hazardous exposures possible. DL--Transmitter dummy loaded. SH

  17. Skin dose measurements using radiochromic films, TLDS and ionisation chamber and comparison with Monte Carlo simulation.

    PubMed

    Alashrah, Saleh; Kandaiya, Sivamany; Maalej, Nabil; El-Taher, A

    2014-12-01

    Estimation of the surface dose is very important for patients undergoing radiation therapy. The purpose of this study is to investigate the dose at the surface of a water phantom at a depth of 0.007 cm as recommended by the International Commission on Radiological Protection and International Commission on Radiation Units and Measurement with radiochromic films (RFs), thermoluminescent dosemeters and an ionisation chamber in a 6-MV photon beam. The results were compared with the theoretical calculation using Monte Carlo (MC) simulation software (MCNP5, BEAMnrc and DOSXYZnrc). The RF was calibrated by placing the films at a depth of maximum dose (d(max)) in a solid water phantom and exposing it to doses from 0 to 500 cGy. The films were scanned using a transmission high-resolution HP scanner. The optical density of the film was obtained from the red component of the RGB images using ImageJ software. The per cent surface dose (PSD) and percentage depth dose (PDD) curve were obtained by placing film pieces at the surface and at different depths in the solid water phantom. TLDs were placed at a depth of 10 cm in a solid water phantom for calibration. Then the TLDs were placed at different depths in the water phantom and were exposed to obtain the PDD. The obtained PSD and PDD values were compared with those obtained using a cylindrical ionisation chamber. The PSD was also determined using Monte Carlo simulation of a LINAC 6-MV photon beam. The extrapolation method was used to determine the PSD for all measurements. The PSD was 15.0±3.6% for RF. The TLD measurement of the PSD was 16.0±5.0%. The (0.6 cm(3)) cylindrical ionisation chamber measurement of the PSD was 50.0±3.0%. The theoretical calculation using MCNP5 and DOSXYZnrc yielded a PSD of 15.0±2.0% and 15.7±2.2%. In this study, good agreement between PSD measurements was observed using RF and TLDs with the Monte Carlo calculation. However, the cylindrical chamber measurement yielded an overestimate of the PSD

  18. The assessment of risks from exposure to low-levels of ionizing radiation

    SciTech Connect

    Gilbert, E.S.

    1992-06-01

    This report is concerned with risk assessments for human populations receiving low level radiation doses; workers routinely exposed to radiation, Japanese victims of nuclear bombs, and the general public are all considered. Topics covered include risk estimates for cancer, mortality rates, risk estimates for nuclear site workers, and dosimetry.

  19. Radiation properties and emissivity parameterization of high level thin clouds

    NASA Technical Reports Server (NTRS)

    Wu, M.-L. C.

    1984-01-01

    To parameterize emissivity of clouds at 11 microns, a study has been made in an effort to understand the radiation field of thin clouds. The contributions to the intensity and flux from different sources and through different physical processes are calculated by using the method of successive orders of scattering. The effective emissivity of thin clouds is decomposed into the effective absorption emissivity, effective scattering emissivity, and effective reflection emissivity. The effective absorption emissivity depends on the absorption and emission of the cloud; it is parameterized in terms of optical thickness. The effective scattering emissivity depends on the scattering properties of the cloud; it is parameterized in terms of optical thickness and single scattering albedo. The effective reflection emissivity follows the similarity relation as in the near infrared cases. This is parameterized in terms of the similarity parameter and optical thickness, as well as the temperature difference between the cloud and ground.

  20. Network-level fallout radiation-effects assessment. Final report

    SciTech Connect

    Not Available

    1989-05-12

    The EMP Mitigation Program analyzes, and where feasible, lessens the degradation effects of EMP on national telecommunication resources. The program focuses on the resources of the public switched network (PSN) because the PSN comprises the largest, most diverse set of telecommunication assets in the United States and is the focus of National Security Emergency Preparedness (NSEP) telecommunication enhancement activities. Additionally, the majority of various organizations rely on the PSN to conduct their NSEP telecommunications responsibilities. Telecommunication equipment is most susceptible to high altitude EMP (HEMP) which occurs when a nuclear weapon is detonated at an altitude greater that 50 km above the earth's surface. In addition to studying the effects of EMP, the program has expanded to address the effects of fallout radiation and serve traffic congestion on the PSN.

  1. The ST environment: Expected charged particle radiation levels

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.

    1978-01-01

    The external (surface incident) charged particle radiation, predicted for the ST satellite at the three different mission altitudes, was determined in two ways: (1) by orbital flux-integration and (2) by geographical instantaneous flux-mapping. The latest standard models of the environment were used in this effort. Magnetic field definitions for three nominal circular trajectories and for the geographic mapping positions were obtained from a current field model. Spatial and temporal variations or conditions affecting the static environment models were considered and accounted for, wherever possible. Limited shielding and dose evaluations were performed for a simple geometry. Results, given in tabular and graphical form, are analyzed, explained, and discussed. Conclusions are included.

  2. Detection of ultraviolet radiation using tissue equivalent radiochromic gel materials

    NASA Astrophysics Data System (ADS)

    Bero, M. A.; Abukassem, I.

    2009-05-01

    Ferrous Xylenol-orange Gelatin gel (FXG) is known to be sensitive to ionising radiation such as γ and X-rays. The effect of ionising radiation is to produce an increase in the absorption over a wide region of the visible spectrum, which is proportional to the absorbed dose. This study demonstrates that FXG gel is sensitive to ultraviolet radiation and therefore it could functions as UV detector. Short exposure to UV radiation produces linear increase in absorption measured at 550nm, however high doses of UV cause the ion indicator colour to fad away in a manner proportional to the incident UV energy. Light absorbance increase at the rate of 1.1% per minute of irradiation was monitored. The exposure level at which the detector has linear response is comparable to the natural summer UV radiation. Evaluating the UV ability to pass through tissue equivalent gel materials shows that most of the UV gets absorbed in the first 5mm of the gel materials, which demonstrate the damaging effects of this radiation type on human skin and eyes. It was concluded that FXG gel dosimeter has the potential to offer a simple, passive ultraviolet radiation detector with sensitivity suitable to measure and visualises the natural sunlight UV exposure directly by watching the materials colour changes.

  3. Infrared radiation and inversion population of CO2 laser levels in Venusian and Martian atmospheres

    NASA Technical Reports Server (NTRS)

    Gordiyets, B. F.; Panchenko, V. Y.

    1983-01-01

    Formation mechanisms of nonequilibrium 10 micron CO2 molecule radiation and the possible existence of a natural laser effect in the upper atmospheres of Venus and Mars are theoretically studied. An analysis is made of the excitation process of CO2 molecule vibrational-band levels (with natural isotropic content) induced by direct solar radiation in bands 10.6, 9.4, 4.3, 2.7 and 2.0 microns. The model of partial vibrational-band temperatures was used in the case. The problem of IR radiation transfer in vibrational-rotational bands was solved in the radiation escape approximation.

  4. Effects of combined radiofrequency radiation exposure on levels of reactive oxygen species in neuronal cells

    PubMed Central

    Kang, Kyoung Ah; Lee, Hyung Chul; Lee, Je-Jung; Hong, Mi-Na; Park, Myung-Jin; Lee, Yun-Sil; Choi, Hyung-Do; Kim, Nam; Ko, Young-Gyu; Lee, Jae-Seon

    2014-01-01

    The objective of this study was to investigate the effects of the combined RF radiation (837 MHz CDMA plus 1950 MHz WCDMA) signal on levels of intracellular reactive oxygen species (ROS) in neuronal cells. Exposure of the combined RF signal was conducted at specific absorption rate values of 2 W/kg of CDMA plus 2 W/kg of WCDMA for 2 h. Co-exposure to combined RF radiation with either H2O2 or menadione was also performed. The experimental exposure groups were incubator control, sham-exposed, combined RF radiation-exposed with or without either H2O2 or menadione groups. The intracellular ROS level was measured by flow cytometry using the fluorescent probe dichlorofluorescein diacetate. Intracellular ROS levels were not consistently affected by combined RF radiation exposure alone in a time-dependent manner in U87, PC12 or SH-SY5Y cells. In neuronal cells exposed to combined RF radiation with either H2O2 or menadione, intracellular ROS levels showed no statically significant alteration compared with exposure to menadione or H2O2 alone. These findings indicate that neither combined RF radiation alone nor combined RF radiation with menadione or H2O2 influences the intracellular ROS level in neuronal cells such as U87, PC12 or SH-SY5Y. PMID:24105709

  5. COMPREHENSIVE DATA CONCERNING COSMIC RADIATION DOSES AT GROUND LEVEL AND IN-FLIGHTS FOR TURKEY.

    PubMed

    Parmaksız, A

    2016-12-01

    Cosmic radiation doses of individuals living in 81 cities in Turkey were estimated by using CARI-6 software. Annual cosmic radiation doses of individuals were found to be between 308 and 736 µSv y(-1) at ground level. The population-weighted annual effective dose from cosmic radiation was determined to be 387 µSv y(-1) for Turkey. Cosmic radiation doses on-board for 137 (60 domestic and 77 international) flights varied from 1.2 to 83 µSv. It was estimated that six or over long-route round-trip air travels may cause cosmic radiation dose above the permissible limit for member of the public, i.e. 1 mSv y(-1) According to the assumption of flights throughout 800 h on each route, cosmic radiation doses were found to be between 1.0 and 4.8 mSv for aircrew.

  6. Base-level management of radio-frequency radiation-protection program. Final report

    SciTech Connect

    Rademacher, S.E.; Montgomery, N.D.

    1989-04-01

    AFOEHL developed this report to assist the base-level aerospace medical team manage their radio-frequency radiation-protection program. This report supersedes USAFOEHL Report 80-42, 'A Practical R-F Guide for BEES.'

  7. Base-level management of radio-frequency radiation-protection program. Final report

    SciTech Connect

    Rademacher, S.E.; Montgomery, N.D.

    1989-04-01

    AFOEHL developed this report to assist the base-level aerospace medical team manage their radio-frequency radiation protection program. This report supersedes USAFOEHL Report 80-42, 'A practical R-F Guide for BEES.'

  8. Cell-oriented alternatives to dose, quality factor, and dose equivalent for low-level radiation

    SciTech Connect

    Sondhaus, C.A.; Bond, V.P.; Feinendegen, L.E. )

    1990-07-01

    Randomly occurring energy deposition events produced by low levels of ionizing radiation interacting with tissue deliver variable amounts of energy to sensitive target volumes within a small fraction of the tissue cell population. A model is described in which an experimentally derived function relating event size to cell response probability operates mathematically on the microdosimetric event size distribution characterizing a given irradiation and thus determines the total fractional number of responding cells; this fraction measures the effectiveness of the given radiation. Applying this cell response or hit size effectiveness function (HSEF) to different radiations and normalizing to equal numbers of responses produced by each radiation should define its radiation quality, or relative effectiveness, on a more nearly absolute basis than do the absorbed dose and dose equivalent, both of which are confounded when applied to low-level irradiations. Similar cell response probability functions calculated from different experimental data are presented.

  9. Cell-oriented alternatives to dose, quality factor, and dose equivalent for low-level radiation.

    PubMed

    Sondhaus, C A; Bond, V P; Feinendegen, L E

    1990-07-01

    Randomly occurring energy deposition events produced by low levels of ionizing radiation interacting with tissue deliver variable amounts of energy to sensitive target volumes within a small fraction of the tissue cell population. A model is described in which an experimentally derived function relating event size to cell response probability operates mathematically on the microdosimetric event size distribution characterizing a given irradiation and thus determines the total fractional number of responding cells; this fraction measures the effectiveness of the given radiation. Applying this cell response or hit size effectiveness function (HSEF) to different radiations and normalizing to equal numbers of responses produced by each radiation should define its radiation quality, or relative effectiveness, on a more nearly absolute basis than do the absorbed dose and dose equivalent, both of which are confounded when applied to low-level irradiations. Similar cell response probability functions calculated from different experimental data are presented.

  10. Alternative interpretations of statistics on health effects of low-level radiation

    SciTech Connect

    Hamilton, L.D.

    1983-11-01

    Four examples of the interpretation of statistics of data on low-level radiation are reviewed: (a) genetic effects of the atomic bombs at Hiroshima and Nagasaki, (b) cancer at Rocky Flats, (c) childhood leukemia and fallout in Utah, and (d) cancer among workers at the Portsmouth Naval Shipyard. Aggregation of data, adjustment for age, and other problems related to the determination of health effects of low-level radiation are discussed. Troublesome issues related to post hoc analysis are considered.

  11. Mechanism of low-level microwave radiation effect on nervous system.

    PubMed

    Hinrikus, Hiie; Bachmann, Maie; Karai, Denis; Lass, Jaanus

    2017-01-01

    The aim of this study is to explain the mechanism of the effect of low-level modulated microwave radiation on brain bioelectrical oscillations. The proposed model of excitation by low-level microwave radiation bases on the influence of water polarization on hydrogen bonding forces between water molecules, caused by this the enhancement of diffusion and consequences on neurotransmitters transit time and neuron resting potential. Modulated microwave radiation causes periodic alteration of the neurophysiologic parameters and parametric excitation of brain bioelectric oscillations. The experiments to detect logical outcome of the mechanism on physiological level were carried out on 15 human volunteers. The 450-MHz microwave radiation modulated at 7, 40 and 1000 Hz frequencies was applied at the field power density of 0.16 mW/cm(2). A relative change in the EEG power with and without radiation during 10 cycles was used as a quantitative measure. Experimental data demonstrated that modulated at 40 Hz microwave radiation enhanced EEG power in EEG alpha and beta frequency bands. No significant alterations were detected at 7 and 1000 Hz modulation frequencies. These results are in good agreement with the theory of parametric excitation of the brain bioelectric oscillations caused by the periodic alteration of neurophysiologic parameters and support the proposed mechanism. The proposed theoretical framework has been shown to predict the results of experimental study. The suggested mechanism, free of the restrictions related to field strength or time constant, is the first one providing explanation of low-level microwave radiation effects.

  12. Defining Top-of-Atmosphere Flux Reference Level for Earth Radiation Budget Studies

    NASA Technical Reports Server (NTRS)

    Loeb, N. G.; Kato, S.; Wielicki, B. A.

    2002-01-01

    To estimate the earth's radiation budget at the top of the atmosphere (TOA) from satellite-measured radiances, it is necessary to account for the finite geometry of the earth and recognize that the earth is a solid body surrounded by a translucent atmosphere of finite thickness that attenuates solar radiation differently at different heights. As a result, in order to account for all of the reflected solar and emitted thermal radiation from the planet by direct integration of satellite-measured radiances, the measurement viewing geometry must be defined at a reference level well above the earth s surface (e.g., 100 km). This ensures that all radiation contributions, including radiation escaping the planet along slant paths above the earth s tangent point, are accounted for. By using a field-of- view (FOV) reference level that is too low (such as the surface reference level), TOA fluxes for most scene types are systematically underestimated by 1-2 W/sq m. In addition, since TOA flux represents a flow of radiant energy per unit area, and varies with distance from the earth according to the inverse-square law, a reference level is also needed to define satellite-based TOA fluxes. From theoretical radiative transfer calculations using a model that accounts for spherical geometry, the optimal reference level for defining TOA fluxes in radiation budget studies for the earth is estimated to be approximately 20 km. At this reference level, there is no need to explicitly account for horizontal transmission of solar radiation through the atmosphere in the earth radiation budget calculation. In this context, therefore, the 20-km reference level corresponds to the effective radiative top of atmosphere for the planet. Although the optimal flux reference level depends slightly on scene type due to differences in effective transmission of solar radiation with cloud height, the difference in flux caused by neglecting the scene-type dependence is less than 0.1%. If an inappropriate

  13. Base-Level Management of Laser Radiation Protection Program

    DTIC Science & Technology

    1992-02-01

    lasers exempt from 21 CFR, Subchapter J, under FDA Exemption No 76 EL-01 DoD. Currently under revision. E. Practical comments on laser safety. Despite the...transition from Q, to Qm must be sufficiently fast and energy level Qm must be relatively stable. Under these conditions, the population of atoms at energy...low pressure , the atoms or molecules are in constant random motion. The frequency of the emission is subject to variations caused by Doppler

  14. BEIR-III report and the health effects of low-level radiation

    SciTech Connect

    Fabrikant, J.I.

    1980-01-01

    The present BEIR-III Committee has not highlighted any controversy over the health effects of low-level radiation. In its evaluation of the experimental data and epidemiological surveys, the Committee has carefully reviewed and assessed the value of all the available scientific evidence for estimating numerical risk coefficients for the health hazards to human populations exposed to low levels of ionizing radiation. Responsible public awareness of the possible health effects of ionizing radiations from medical and industrial radiation exposure, centers on three important matters of societal concern: (1) to place into perspective the extent of harm to the health of man and his descendants to be expected in the present and in the future from those societal activities involving ionizing radiation; (2) to develop quantitative indices of harm based on dose-effect relationships; such indices could then be used with prudent caution to introduce concepts of the regulation of population doses on the basis of somatic and genetic risks; and (3) to identify the magnitude and extent of radiation activities which could cause harm, to assess their relative significance, and to provide a framework for recommendations on how to reduce unnecessary radiation exposure to human populations. The main difference of the BEIR Committee Report is not so much from new data or new interpretations of existing data, but rather from a philosophical approach and appraisal of existing and future radiation protection resulting from an atmosphere of constantly changing societal conditions and public attitudes. (PCS)

  15. X-33 XRS-2200 Linear Aerospike Engine Sea Level Plume Radiation

    NASA Technical Reports Server (NTRS)

    DAgostino, Mark G.; Lee, Young C.; Wang, Ten-See; Turner, Jim (Technical Monitor)

    2001-01-01

    Wide band plume radiation data were collected during ten sea level tests of a single XRS-2200 engine at the NASA Stennis Space Center in 1999 and 2000. The XRS-2200 is a liquid hydrogen/liquid oxygen fueled, gas generator cycle linear aerospike engine which develops 204,420 lbf thrust at sea level. Instrumentation consisted of six hemispherical radiometers and one narrow view radiometer. Test conditions varied from 100% to 57% power level (PL) and 6.0 to 4.5 oxidizer to fuel (O/F) ratio. Measured radiation rates generally increased with engine chamber pressure and mixture ratio. One hundred percent power level radiation data were compared to predictions made with the FDNS and GASRAD codes. Predicted levels ranged from 42% over to 7% under average test values.

  16. Energy levels and radiative rates for Cr-like Cu VI and Zn VII

    NASA Astrophysics Data System (ADS)

    Aggarwal, K. M.; Bogdanovich, P.; Keenan, F. P.; Kisielius, R.

    2016-09-01

    Energy levels and radiative rates (A-values) for transitions in Cr-like Cu VI and Zn VII are reported. These data are determined in the quasi-relativistic approach (QR), by employing a very large configuration interaction (CI) expansion which is highly important for these ions. No radiative rates are available in the literature to compare with our results, but our calculated energies are in close agreement with those compiled by NIST and other available theoretical data, for a majority of the levels. The A-values (and resultant lifetimes) are listed for all significantly contributing E1, E2 and M1 radiative transitions among the energetically lowest 322 levels of each ion.

  17. Increased Artemis levels confer radioresistance to both high and low LET radiation exposures

    PubMed Central

    2012-01-01

    Background Artemis has a defined role in V(D)J recombination and has been implicated in the repair of radiation induced double-strand breaks. However the exact function(s) of Artemis in DNA repair and its preferred substrate(s) in vivo remain undefined. Our previous work suggests that Artemis is important for the repair of complex DNA damage like that inflicted by high Linear Energy Transfer (LET) radiation. To establish the contribution of Artemis in repairing DNA damage caused by various radiation qualities, we evaluated the effect of over-expressing Artemis on cell survival, DNA repair, and cell cycle arrest after exposure to high and low LET radiation. Results Our data reveal that Artemis over-expression confers marked radioprotection against both types of radiation, although the radioprotective effect was greater following high LET radiation. Inhibitor studies reveal that the radioprotection imparted by Artemis is primarily dependent on DNA-PK activity, and to a lesser extent on ATM kinase activity. Together, these data suggest a DNA-PK dependent role for Artemis in the repair of complex DNA damage. Conclusions These findings indicate that Artemis levels significantly influence radiation toxicity in human cells and suggest that Artemis inhibition could be a practical target for adjuvant cancer therapies. PMID:22713703

  18. Ionisation chamber containing boron as a neutron detector in medical accelerator fields.

    PubMed

    Zielczynski, M; Gryzinski, M A; Golnik, N; Tulik, P

    2007-01-01

    A combination of the recombination principle of H(10) measurements with the use of the ionisation chambers containing boron has been presented, in order to increase the relative sensitivity of the chamber to neutrons by a factor close to the radiation quality factor of photoneutrons. Three types of the chambers were investigated. Two of them were filled with BF(3) and the third one contained electrodes covered with B(4)C. All the chambers were placed in paraffin moderators. The response of the chambers was investigated, depending on gas pressure and polarising voltage. The results showed that it was possible to obtain nearly the same response of the chamber to H(10) for photons and neutrons in a restricted energy range; however, further investigations are needed to make an optimum design.

  19. Airborne laser-spark for ambient desorption/ionisation.

    PubMed

    Bierstedt, Andreas; Riedel, Jens

    2016-01-01

    A novel direct sampling ionisation scheme for ambient mass spectrometry is presented. Desorption and ionisation are achieved by a quasi-continuous laser induced plasma in air. Since there are no solid or liquid electrodes involved the ion source does not suffer from chemical interferences or fatigue originating from erosive burning or from electrode consumption. The overall plasma maintains electro-neutrality, minimising charge effects and accompanying long term drift of the charged particles trajectories. In the airborne plasma approach the ambient air not only serves as the plasma medium but at the same time also slows down the nascent ions via collisional cooling. Ionisation of the analyte molecules does not occur in the plasma itself but is induced by interaction with nascent ionic fragments, electrons and/or far ultraviolet photons in the plasma vicinity. At each individual air-spark an audible shockwave is formed, providing new reactive species, which expands concentrically and, thus, prevents direct contact of the analyte with the hot region inside the plasma itself. As a consequence the interaction volume between plasma and analyte does not exceed the threshold temperature for thermal dissociation or fragmentation. Experimentally this indirect ionisation scheme is demonstrated to be widely unspecific to the chemical nature of the analyte and to hardly result in any fragmentation of the studied molecules. A vast ensemble of different test analytes including polar and non-polar hydrocarbons, sugars, low mass active ingredients of pharmaceuticals as well as natural biomolecules in food samples directly out of their complex matrices could be shown to yield easily accessible yet meaningful spectra. Since the plasma medium is humid air, the chemical reaction mechanism of the ionisation is likely to be similar to other ambient ionisation techniques. Wir stellen hier eine neue Ionisationsmethode für die Umgebungsionisation (ambient ionisation) vor. Sowohl die

  20. High ionisation absorption in low mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Ponti, G.; Bianchi, S.; Muñoz-Darias, T.; De, K.; Fender, R.; Merloni, A.

    2016-05-01

    The advent of the new generation of X-ray telescopes yielded a significant step forward in our understanding of ionised absorption generated in the accretion discs of X-ray binaries. It has become evident that these relatively weak and narrow absorption features, sporadically present in the X-ray spectra of some systems, are actually the signature of equatorial outflows, which might carry away more matter than that being accreted. Therefore, they play a major role in the accretion phenomenon. These outflows (or ionised atmospheres) are ubiquitous during the softer states but absent during the power-law dominated, hard states, suggesting a strong link with the state of the inner accretion disc, presence of the radio-jet and the properties of the central source. Here, we discuss the current understanding of this field.

  1. A CONCEPTUAL FRAMEWORK FOR MANAGING RADIATION DOSE TO PATIENTS IN DIAGNOSTIC RADIOLOGY USING REFERENCE DOSE LEVELS.

    PubMed

    Almén, Anja; Båth, Magnus

    2016-06-01

    The overall aim of the present work was to develop a conceptual framework for managing radiation dose in diagnostic radiology with the intention to support optimisation. An optimisation process was first derived. The framework for managing radiation dose, based on the derived optimisation process, was then outlined. The outset of the optimisation process is four stages: providing equipment, establishing methodology, performing examinations and ensuring quality. The optimisation process comprises a series of activities and actions at these stages. The current system of diagnostic reference levels is an activity in the last stage, ensuring quality. The system becomes a reactive activity only to a certain extent engaging the core activity in the radiology department, performing examinations. Three reference dose levels-possible, expected and established-were assigned to the three stages in the optimisation process, excluding ensuring quality. A reasonably achievable dose range is also derived, indicating an acceptable deviation from the established dose level. A reasonable radiation dose for a single patient is within this range. The suggested framework for managing radiation dose should be regarded as one part of the optimisation process. The optimisation process constitutes a variety of complementary activities, where managing radiation dose is only one part. This emphasises the need to take a holistic approach integrating the optimisation process in different clinical activities.

  2. Effect of radiation and age on immunoglobulin levels in rhesus monkeys (Macaca mulatta)

    NASA Technical Reports Server (NTRS)

    Stone, W. H.; Saphire, D. G.; Hackleman, S. M.; Braun, A. M.; Pennington, P.; Scheffler, J.; Wigle, J. C.; Cox, A. B.

    1994-01-01

    We report the results of a study on the immunoglobulin levels of rhesus monkeys (Macaca mulatta) in a colony consisting of the survivors of monkeys that received a single whole-body exposure to protons, electrons or X rays between 1964 and 1969. This colony has been maintained to assess the long-term effects of ionizing radiation on astronauts and high-flying pilots. Of the original 358 monkeys that were retained for lifetime studies, 129 (97 irradiated and 32 controls) were available for our study. We found no significant difference between the irradiated and control monkeys in mean levels of IgA, IgG and IgM, irrespective of the radiation treatment. The availability of these aged monkeys provided a unique opportunity to compare their immunoglobulin levels to those of other monkeys of various ages, and thus assess the effect of age on immunoglobulin levels. We found that only the IgA levels increase with age.

  3. Erich Regener and the ionisation maximum of the atmosphere

    NASA Astrophysics Data System (ADS)

    Carlson, P.; Watson, A. A.

    2014-12-01

    In the 1930s the German physicist Erich Regener (1881-1955) did important work on the measurement of the rate of production of ionisation deep under water and in the atmosphere. Along with one of his students, Georg Pfotzer, he discovered the altitude at which the production of ionisation in the atmosphere reaches a maximum, often, but misleadingly, called the Pfotzer maximum. Regener was one of the first to estimate the energy density of cosmic rays, an estimate that was used by Baade and Zwicky to bolster their postulate that supernovae might be their source. Yet Regener's name is less recognised by present-day cosmic ray physicists than it should be, largely because in 1937 he was forced to take early retirement by the National Socialists as his wife had Jewish ancestors. In this paper we briefly review his work on cosmic rays and recommend an alternative naming of the ionisation maximum. The influence that Regener had on the field through his son, his son-in-law, his grandsons and his students, and through his links with Rutherford's group in Cambridge, is discussed in an appendix. Regener was nominated for the Nobel Prize in Physics by Schrödinger in 1938. He died in 1955 at the age of 73.

  4. Radiation induced deep level defects in bipolar junction transistors under various bias conditions

    NASA Astrophysics Data System (ADS)

    Liu, Chaoming; Yang, Jianqun; Li, Xingji; Ma, Guoliang; Xiao, Liyi; Bollmann, Joachim

    2015-12-01

    Bipolar junction transistor (BJT) is sensitive to ionization and displacement radiation effects in space. In this paper, 35 MeV Si ions were used as irradiation source to research the radiation damage on NPN and PNP bipolar transistors. The changing of electrical parameters of transistors was in situ measured with increasing irradiation fluence of 35 MeV Si ions. Using deep level transient spectroscopy (DLTS), defects in the bipolar junction transistors under various bias conditions are measured after irradiation. Based on the in situ electrical measurement and DLTS spectra, it is clearly that the bias conditions can affect the concentration of deep level defects, and the radiation damage induced by heavy ions.

  5. Sunlight-Exposed Biofilm Microbial Communities Are Naturally Resistant to Chernobyl Ionizing-Radiation Levels

    PubMed Central

    Ragon, Marie; Restoux, Gwendal; Moreira, David; Møller, Anders Pape; López-García, Purificación

    2011-01-01

    Background The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. Methodology/Principal Findings To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta) and ascomycete fungi (Ascomycota) dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU) present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. Conclusions/Significance Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in terms of general

  6. New Methodology for First Principle Calculations of Electrical Levels for Radiation Induced Defects in Silicates

    DTIC Science & Technology

    2005-02-22

    GRANT NUMBER 4. TITLE AND SUBTITLE New Methodology For First Principle Calculations Of Electrical Levels For Radiation Induced Defects In Silicates ...materials, space materials, Silicon on Insulator ( SOI ) materials 16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE PERSON DONALD J SMITH

  7. Determining the Knowledge Level of Pre-Service Teachers' on Radioactivity and Radiation

    ERIC Educational Resources Information Center

    Ergul, N. Remziye

    2012-01-01

    This study investigated the basic knowledge levels of teacher candidates' from different branches regarding the subjects of radiation and radioactivity. 42 variables were determined in relation to the specified titles. In the preparation stage of determining the variables, all the related programs were examined, and attention was paid to include…

  8. NATIONAL- AND STATE-LEVEL EMISSIONS ESTIMATES OF RADIATIVELY IMPORTANT TRACE GASES (RITGS) FROM ANTHROPOGENIC SOURCES

    EPA Science Inventory

    The report documents the development of national- and state- level emissions estimates of radiatively important trace gases (RlTGs). Emissions estimates are presented for the principal anthropogenic sources of carbon dioxide (CO2), methane (CH4), chlorofluorocarbons (CFCs), and o...

  9. Broadband EM radiation amplification by means of a monochromatically driven two-level system

    NASA Astrophysics Data System (ADS)

    Soldatov, Andrey V.

    2017-02-01

    It is shown that a two-level quantum system possessing dipole moment operator with permanent non-equal diagonal matrix elements and driven by external semiclassical monochromatic high-frequency electromagnetic (EM) (laser) field can amplify EM radiation waves of much lower frequency.

  10. Determining the Knowledge Level of Pre-Service Teachers' on Radioactivity and Radiation

    ERIC Educational Resources Information Center

    Ergul, N. Remziye

    2012-01-01

    This study investigated the basic knowledge levels of teacher candidates from different branches regarding the subjects of radiation and radioactivity. 42 variables were determined in relation to the specified titles. In the preparation stage of determining the variables, all the related programs were examined, and attention was paid to include…

  11. Autocorrelation in ultraviolet radiation measured at ground level using detrended fluctuation analysis

    NASA Astrophysics Data System (ADS)

    da Silva Filho, Paulo Cavalcante; da Silva, Francisco Raimundo; Corso, Gilberto

    2016-07-01

    In this study, we analyzed the autocorrelation among four ultraviolet (UV) radiation data sets obtained at 305 nm, 320 nm, 340 nm, and 380 nm. The data were recorded at ground level at the INPE climate station in Natal, RN, Brazil, which is a site close to the equator. The autocorrelations were computed by detrended fluctuation analysis (DFA) to estimate the index α. We found that the ​fluctuations in the UV radiation data were fractal, with scale-free behavior at a DFA index α ≃ 0.7. In addition, we performed a power law spectral analysis, which showed that the power spectrum exhibited a power law behavior with an exponent of β ≃ 0.45. Given that the theoretical result is β = 2 α - 1, these two results are in good agreement. Moreover, the application of the DFA ​method to the UV radiation data required detrending using a polynomial with an order of at least eight, which was related to the complex daily solar radiation curve obtained at ground level in a tropical region. The results indicated that the α exponent of UV radiation is similar to other climatic records such as air temperature, wind, or rain, but not solar activity.

  12. Enabling Radiative Transfer on AMR grids in CRASH

    NASA Astrophysics Data System (ADS)

    Hariharan, N.; Graziani, L.; Ciardi, B.; Miniati, F.; Bungartz, H.-J.

    2017-01-01

    We introduce CRASH-AMR, a new version of the cosmological Radiative Transfer (RT) code CRASH, enabled to use refined grids. This new feature allows us to attain higher resolution in our RT simulations and thus to describe more accurately ionisation and temperature patterns in high density regions. We have tested CRASH-AMR by simulating the evolution of an ionised region produced by a single source embedded in gas at constant density, as well as by a more realistic configuration of multiple sources in an inhomogeneous density field. While we find an excellent agreement with the previous version of CRASH when the AMR feature is disabled, showing that no numerical artifact has been introduced in CRASH-AMR, when additional refinement levels are used the code can simulate more accurately the physics of ionised gas in high density regions. This result has been attained at no computational loss, as RT simulations on AMR grids with maximum resolution equivalent to that of a uniform cartesian grid can be run with a gain of up to 60% in computational time.

  13. Lower prevalence but similar fitness in a parasitic fungus at higher radiation levels near Chernobyl.

    PubMed

    Aguileta, Gabriela; Badouin, Helene; Hood, Michael E; Møller, Anders P; Le Prieur, Stephanie; Snirc, Alodie; Siguenza, Sophie; Mousseau, Timothy A; Shykoff, Jacqui A; Cuomo, Christina A; Giraud, Tatiana

    2016-07-01

    Nuclear disasters at Chernobyl and Fukushima provide examples of effects of acute ionizing radiation on mutations that can affect the fitness and distribution of species. Here, we investigated the prevalence of Microbotryum lychnidis-dioicae, a pollinator-transmitted fungal pathogen of plants causing anther-smut disease in Chernobyl, its viability, fertility and karyotype variation, and the accumulation of nonsynonymous mutations in its genome. We collected diseased flowers of Silene latifolia from locations ranging by more than two orders of magnitude in background radiation, from 0.05 to 21.03 μGy/h. Disease prevalence decreased significantly with increasing radiation level, possibly due to lower pollinator abundance and altered pollinator behaviour. Viability and fertility, measured as the budding rate of haploid sporidia following meiosis from the diploid teliospores, did not vary with increasing radiation levels and neither did karyotype overall structure and level of chromosomal size heterozygosity. We sequenced the genomes of twelve samples from Chernobyl and of four samples collected from uncontaminated areas and analysed alignments of 6068 predicted genes, corresponding to 1.04 × 10(7)  base pairs. We found no dose-dependent differences in substitution rates (neither dN, dS, nor dN/dS). Thus, we found no significant evidence of increased deleterious mutation rates at higher levels of background radiation in this plant pathogen. We even found lower levels of nonsynonymous substitution rates in contaminated areas compared to control regions, suggesting that purifying selection was stronger in contaminated than uncontaminated areas. We briefly discuss the possibilities for a mechanistic basis of radio resistance in this nonmelanized fungus.

  14. Effect of low-level alpha-radiation on bioluminescent assay systems of various complexity.

    PubMed

    Rozhko, Tatiana V; Kudryasheva, Nadezhda S; Kuznetsov, Alexander M; Vydryakova, Galina A; Bondareva, Lydia G; Bolsunovsky, Alexander Ya

    2007-01-01

    This study addresses the effects of low-level alpha-radiation on bioluminescent assay systems of different levels of organization: in vivo and in vitro. Three bioluminescent assay systems are used: intact bacteria, lyophilized bacteria, and bioluminescent system of coupled enzyme reactions. Solutions of 241Am(NO3)3 are used as a source of alpha-radiation. It has been shown that activation processes predominate in all the three bioluminescent assay systems subjected to short-term exposure (20-55 h) and inhibition processes in the systems subjected to longer-term exposure to radiation. It has been found that these effects are caused by the radiation component of 241Am3+ impact. The intensity of the 241Am3+ effect on the bioluminescent assay systems has been shown to depend on the 241Am3+ concentration, level of organization and integrity of the bioluminescent assay system. The bioluminescent assay systems in vivo have been found to be highly sensitive to 241Am3+ (up to 10(-17) M).

  15. Assessing risks from occupational exposure to low-level radiation: The statistician's role

    SciTech Connect

    Gilbert, E.S.

    1989-06-01

    Currently, several epidemiological studies of workers who have been exposed occupationally to radiation are being conducted. These include workers in the United States, Great Britain, and Canada, involved in the production of both defense materials and nuclear power. A major reason for conducting these studies is to evaluate possible adverse health effects that may have resulted because of the radiation exposure received. The general subject of health effects resulting from low levels of radiation, including these worker studies, has attracted the attention of various news media, and has been the subject of considerable controversy. These studies provide a good illustration of certain other aspects of the statistician's role; namely, communication and adequate subject matter knowledge. A competent technical job is not sufficient if these other aspects are not fulfilled.

  16. Energy levels and radiative rates for transitions in Fe V, Co VI and Ni VII

    NASA Astrophysics Data System (ADS)

    Aggarwal, K. M.; Bogdanovich, P.; Keenan, F. P.; Kisielius, R.

    2017-03-01

    Energy levels, Landé g-factors and radiative lifetimes are reported for the lowest 182 levels of the 3d4, 3d34s and 3d34p configurations of Fe V, Co VI and Ni VII. Additionally, radiative rates (A-values) have been calculated for the E1, E2 and M1 transitions among these levels. The calculations have been performed in a quasi-relativistic approach (QR) with a very large configuration interaction (CI) wavefunction expansion, which has been found to be necessary for these ions. Our calculated energies for all ions are in excellent agreement with the available measurements, for most levels. Discrepancies among various calculations for the radiative rates of E1 transitions in Fe V are up to a factor of two for stronger transitions (f ≥ 0.1), and larger (over an order of magnitude) for weaker ones. The reasons for these discrepancies have been discussed and mainly are due to the differing amount of CI and methodologies adopted. However, there are no appreciable discrepancies in similar data for M1 and E2 transitions, or the g-factors for the levels of Fe V, the only ion for which comparisons are feasible.

  17. Radiation-induced reductions in transporter mRNA levels parallel reductions in intestinal sugar transport

    PubMed Central

    Roche, Marjolaine; Neti, Prasad V. S. V.; Kemp, Francis W.; Agrawal, Amit; Attanasio, Alicia; Douard, Véronique; Muduli, Anjali; Azzam, Edouard I.; Norkus, Edward; Brimacombe, Michael; Howell, Roger W.

    2010-01-01

    More than a century ago, ionizing radiation was observed to damage the radiosensitive small intestine. Although a large number of studies has since shown that radiation reduces rates of intestinal digestion and absorption of nutrients, no study has determined whether radiation affects mRNA expression and dietary regulation of nutrient transporters. Since radiation generates free radicals and disrupts DNA replication, we tested the hypotheses that at doses known to reduce sugar absorption, radiation decreases the mRNA abundance of sugar transporters SGLT1 and GLUT5, prevents substrate regulation of sugar transporter expression, and causes reductions in sugar absorption that can be prevented by consumption of the antioxidant vitamin A, previously shown by us to radioprotect the testes. Mice were acutely irradiated with 137Cs gamma rays at doses of 0, 7, 8.5, or 10 Gy over the whole body. Mice were fed with vitamin A-supplemented diet (100× the control diet) for 5 days prior to irradiation after which the diet was continued until death. Intestinal sugar transport was studied at days 2, 5, 8, and 14 postirradiation. By day 8, d-glucose uptake decreased by ∼10–20% and d-fructose uptake by 25–85%. With increasing radiation dose, the quantity of heterogeneous nuclear RNA increased for both transporters, whereas mRNA levels decreased, paralleling reductions in transport. Enterocytes of mice fed the vitamin A supplement had ≥ 6-fold retinol concentrations than those of mice fed control diets, confirming considerable intestinal vitamin A uptake. However, vitamin A supplementation had no effect on clinical or transport parameters and afforded no protection against radiation-induced changes in intestinal sugar transport. Radiation markedly reduced GLUT5 activity and mRNA abundance, but high-d-fructose diets enhanced GLUT5 activity and mRNA expression in both unirradiated and irradiated mice. In conclusion, the effect of radiation may be posttranscriptional, and

  18. Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells.

    PubMed

    Canuto, K S; Sergio, L P S; Guimarães, O R; Geller, M; Paoli, F; Fonseca, A S

    2015-07-10

    Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia coli cells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficient E. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out.

  19. Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells.

    PubMed

    Canuto, K S; Sergio, L P S; Guimarães, O R; Geller, M; Paoli, F; Fonseca, A S

    2015-10-01

    Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia colicells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficientE. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out.

  20. Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells

    PubMed Central

    Canuto, K.S.; Sergio, L.P.S.; Guimarães, O.R.; Geller, M.; Paoli, F.; Fonseca, A.S.

    2015-01-01

    Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia colicells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficientE. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out. PMID:26445338

  1. Lost life expectancy rate: An application to environmental levels of radiation

    SciTech Connect

    Johnson, W.H.; Kearfott, K.J.

    1997-08-01

    The risk index Lost Life Expectancy Rate (LLER) provides a unitless number (time of life expectancy lost per time exposed) describing the risk from exposure to a given hazard or from partaking in a given activity. Simple equations to calculate the LLER from radiation-induced cancers caused by an exposure to low-level radiation were derived using the relative risk models developed by the Nuclear Regulatory Commission (upper bound estimate), the United Nations Scientific Committee on the Effects of Atomic Radiation-1988, and the National Academy of Science`s Committee on the Biological Effects of Ionizing Radiation (BEIR V). Estimates of the LLER to an average person from a continuous exposure to 0.1 {mu}Sv h{sup -1} based on these models, respectively, are 5.5 x 10{sup -4}, 9.5 x 10{sup -4}, and 9.4 x 10{sup -4}. These values compare to LLERs of 0.015 from occupational accidents, 0.25 from being an automobile passenger, and 2.0 from cigarette smoking. Factors effecting LLER from radiation exposures examined in this work include dose rate, age, sex, race and smoking status. 22 refs., 3 figs., 2 tabs.

  2. Recommended Radiation Protection Practices for Low-Level Waste Disposal Sites

    SciTech Connect

    Hadlock, D. E.; Hooker, C. D.; Herrington, W. N.; Gilchrist, R. L.

    1983-12-01

    The United States Nuclear Regulatory Commission contracted with Pacific Northwest Laboratory (PNL) to provide technical assistance in estsblishing operational guidelines, with respect to radiation control programs and methods of minimizing occupational radiation exposure, at Low-Level Waste (LLW) dis- posal sites. The PNL, through site visits, evaluated operations at LLW dis- posal sites to determine the adequacy of current practices in maintaining occupational exposures as low as is reasonably achievable (ALARA). The data sought included the specifics of: ALARA programs, training programs, external exposure control , internal exposure control , respiratory protection, survei 1 - lance, radioactive waste management, facilities and equipment, and external dose analysis. The results of the study indicated the following: The Radiation Protection and ALARA programs at the three commercial LLW disposal sites were observed to be adequate in scope and content compared to similar programs at other types of nuclear facilities. However, it should be noted that there were many areas that could be improved upon to help ensure the health and safety of the occupa- tionally exposed individuals. As a result, radiation protection practices were recommended with related rationales in order to reduce occupational exposures as far below specified radiation limits as is reasonably achievable. In addition, recommendations were developed for achieving occupational exposure ALARA under the Regulatory Requirements issued in 10 CFR Part 61.

  3. Effects of electromagnetic radiation from a cellular telephone on the oxidant and antioxidant levels in rabbits.

    PubMed

    Irmak, M Kemal; Fadillioğlu, Ersin; Güleç, Mukaddes; Erdoğan, Hasan; Yağmurca, Murat; Akyol, Omer

    2002-12-01

    The number of reports on the effects induced by electromagnetic radiation (EMR) in various cellular systems is still increasing. Until now no satisfactory mechanism has been proposed to explain the biological effects of this radiation. Oxygen free radicals may play a role in mechanisms of adverse effects of EMR. This study was undertaken to investigate the influence of electromagnetic radiation of a digital GSM mobile telephone (900 MHz) on oxidant and antioxidant levels in rabbits. Adenosine deaminase, xanthine oxidase, catalase, myeloperoxidase, superoxide dismutase (SOD) and glutathione peroxidase activities as well as nitric oxide (NO) and malondialdehyde levels were measured in sera and brains of EMR-exposed and sham-exposed rabbits. Serum SOD activity increased, and serum NO levels decreased in EMR-exposed animals compared to the sham group. Other parameters were not changed in either group. This finding may indicate the possible role of increased oxidative stress in the pathophysiology of adverse effect of EMR. Decreased NO levels may also suggest a probable role of NO in the adverse effect.

  4. Energy levels, radiative rates, and lifetimes for transitions in W LVIII

    SciTech Connect

    Aggarwal, Kanti M. Keenan, Francis P.

    2014-11-15

    Energy levels and radiative rates are reported for transitions in Cl-like W LVIII. Configuration interaction (CI) has been included among 44 configurations (generating 4978 levels) over a wide energy range up to 363 Ryd, and the general-purpose relativistic atomic structure package (GRASP) adopted for the calculations. Since no other results of comparable complexity are available, calculations have also been performed with the flexible atomic code (FAC), which help in assessing the accuracy of our results. Energies are listed for the lowest 400 levels (with energies up to ∼98 Ryd), which mainly belong to the 3s{sup 2}3p{sup 5}, 3s3p{sup 6}, 3s{sup 2}3p{sup 4}3d, 3s{sup 2}3p{sup 3}3d{sup 2}, 3s3p{sup 4}3d{sup 2}, 3s{sup 2}3p{sup 2}3d{sup 3}, and 3p{sup 6}3d configurations, and radiative rates are provided for four types of transitions, i.e. E1, E2, M1, and M2. Our energy levels are assessed to be accurate to better than 0.5%, whereas radiative rates (and lifetimes) should be accurate to better than 20% for a majority of the strong transitions.

  5. Radioactivity levels in the mostly local foodstuff consumed by residents of the high level natural radiation areas of Ramsar, Iran.

    PubMed

    Fathabadi, Nasrin; Salehi, Ali Akbar; Naddafi, Kazem; Kardan, Mohammad Reza; Yunesian, Masud; Nodehi, Ramin Nabizadeh; Deevband, Mohammad Reza; Shooshtari, Molood Gooniband; Hosseini, Saeedeh Sadat; Karimi, Mahtab

    2017-04-01

    Among High Level Natural Radiation Areas (HLNRAs) all over the world, the northern coastal city of Ramsar has been considered enormously important. Many studies have measured environmental radioactivity in Ramsar, however, no survey has been undertaken to measure concentrations in the diets of residents. This study determined the (226)Ra activity concentration in the daily diet of people of Ramsar. The samples were chosen from both normal and high level natural radiation areas and based on the daily consumption patterns of residents. About 150 different samples, which all are local and have the highest consumption, were collected during the four seasons. In these samples, after washing and drying and pretreatment, the radionuclide was determined by α-spectrometry. The mean radioactivity concentration of (226)Ra ranged between 5 ± 1 mBq kg(-1) wet weight (chino and meat) to 725 ± 480 mBq kg(-1) for tea dry leaves. The (226)Ra activity concentrations compared with the reference values of UNSCEAR appear to be higher in leafy vegetables, milk and meat product. Of the total daily dietary (226)Ra exposure for adults in Ramsar, the largest percentage was from eggs. The residents consuming eggs from household chickens may receive an elevated dose in the diet.

  6. Intercomparison of ionisation chamber measurements from (125)I seeds.

    PubMed

    Davies, J B; Enari, K F; Baldock, C

    2007-05-01

    The reference air kerma rates of a set of individual (125)I seeds were calculated from current measurements of a calibrated re-entrant ionisation chamber. Single seeds were distributed to seven Australian brachytherapy centres for the same measurement with the user's instrumentation. Results are expressed as the ratio of the reference air kerma rate measured by the Australian Nuclear Science & Technology Organisation (ANSTO) to the reference air kerma rate measured at the centre. The intercomparison ratios of all participants were within +/-5% of unity.

  7. NICIL: Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library

    NASA Astrophysics Data System (ADS)

    Wurster, James

    2016-08-01

    NICIL (Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library) calculates the ionization values and the coefficients of the non-ideal magnetohydrodynamics terms of Ohmic resistivity, the Hall effect, and ambipolar diffusion. Written as a standalone Fortran90 module that can be implemented in existing codes, NICIL is fully parameterizable, allowing the user to choose which processes to include and decide the values of the free parameters. The module includes both cosmic ray and thermal ionization; the former includes two ion species and three species of dust grains (positively charged, negatively charged and neutral), and the latter includes five elements which can be doubly ionized.

  8. Estimation of radiofrequency power leakage from microwave ovens for dosimetric assessment at nonionizing radiation exposure levels.

    PubMed

    Lopez-Iturri, Peio; de Miguel-Bilbao, Silvia; Aguirre, Erik; Azpilicueta, Leire; Falcone, Francisco; Ramos, Victoria

    2015-01-01

    The electromagnetic field leakage levels of nonionizing radiation from a microwave oven have been estimated within a complex indoor scenario. By employing a hybrid simulation technique, based on coupling full wave simulation with an in-house developed deterministic 3D ray launching code, estimations of the observed electric field values can be obtained for the complete indoor scenario. The microwave oven can be modeled as a time- and frequency-dependent radiating source, in which leakage, basically from the microwave oven door, is propagated along the complete indoor scenario interacting with all of the elements present in it. This method can be of aid in order to assess the impact of such devices on expected exposure levels, allowing adequate minimization strategies such as optimal location to be applied.

  9. Estimation of Radiofrequency Power Leakage from Microwave Ovens for Dosimetric Assessment at Nonionizing Radiation Exposure Levels

    PubMed Central

    Lopez-Iturri, Peio; de Miguel-Bilbao, Silvia; Aguirre, Erik; Azpilicueta, Leire; Falcone, Francisco; Ramos, Victoria

    2015-01-01

    The electromagnetic field leakage levels of nonionizing radiation from a microwave oven have been estimated within a complex indoor scenario. By employing a hybrid simulation technique, based on coupling full wave simulation with an in-house developed deterministic 3D ray launching code, estimations of the observed electric field values can be obtained for the complete indoor scenario. The microwave oven can be modeled as a time- and frequency-dependent radiating source, in which leakage, basically from the microwave oven door, is propagated along the complete indoor scenario interacting with all of the elements present in it. This method can be of aid in order to assess the impact of such devices on expected exposure levels, allowing adequate minimization strategies such as optimal location to be applied. PMID:25705676

  10. Prediction of Flight-Level Radiation Hazards Due To Solar Energetic Protons

    DTIC Science & Technology

    2006-01-01

    health problems for personnel and soft errors in electronics. Much work has been performed to calculate radiation dose rates at flight levels due to...codes used to calculate dose rates. His discussions helped me gain focus and provided me with the necessary information to critically evaluate the...different processes used in the calculations . Finally, I would like to thank Dr. Herb Sauer from the Cooperative Institute for Research in

  11. Fine-structure energy levels, radiative rates and lifetimes in Si-like nickel

    NASA Astrophysics Data System (ADS)

    Gupta, G. P.; Msezane, A. Z.

    2012-07-01

    Large scale CIV3 calculations of excitation energies from ground state as well as of oscillator strengths and radiative decay rates for all electric-dipole-allowed and intercombination transitions among the fine-structure levels of the terms belonging to the (1s22s22p6)3s23p2, 3s3p3, 3p4, 3s23p3d, 3s23p4s, 3s23p4p, 3s23p4d and 3s23p4f configurations of Ni XV, are performed using very extensive configuration-interaction wave functions. The relativistic effects in intermediate coupling are incorporated by means of the Breit-Pauli Hamiltonian. In order to keep our calculated energy splittings as close as possible to the National Institute of Standard and Technology (NIST) values, we have made small adjustments to the diagonal elements of the Hamiltonian matrices. Our calculated excitation energies, including their ordering, are in excellent agreement with the available NIST results. From our radiative decay rates we have also calculated radiative lifetimes of the fine-structure levels. It is noted that our calculated radiative rates show significant disagreement (23-30%) with those calculated by Ishikawa and Vilkas (2002 Phys. Scr. 65 219) for the transitions involving the 3s3p3(5S2) level. For this high spin level 3s3p3(5S2) our calculated lifetime is found to be in excellent agreement with the experimental value of Träbert et al (1989 Z. Phys. D 11 207). In this calculation, we also predict many additional new and accurate data for various optically allowed and intercombination transitions to complete the void in the existing data.

  12. Advanced Quantum Mechanical Calculation of Superheavy Ions: Energy Levels, Radiation and Finite Nuclear Size Effects

    SciTech Connect

    Glushkov, Alexander V.; Gurnitskaya, E.P.; Loboda, A.V.

    2005-10-26

    Advanced quantum approach to calculation of spectra for superheavy ions with an account of relativistic, correlation, nuclear, radiative effects is developed and based on the gauge invariant quantum electrodynamics (QED) perturbation theory (PT). The Lamb shift polarization part is calculated in the Ueling approximation, self-energy part is defined within a new non-PT procedure of Ivanov-Ivanova. Calculation results for energy levels, hyperfine structure parameters of some heavy elements ions are presented.

  13. The scientific jigsaw puzzle: Fitting the pieces of the low-level radiation debate

    SciTech Connect

    Beyea, Jan

    2012-05-01

    Quantitative risk estimates from exposure to ionizing radiation are dominated by analysis of the one-time exposures received by the Japanese survivors at Hiroshima and Nagasaki. Three recent epidemiologic studies suggest that the risk from protracted exposure is no lower, and in fact may be higher, than from single exposures. There is near-universal acceptance that epidemiologic data demonstrates an excess risk of delayed cancer incidence above a dose of 0.1 sievert (Sv), which, for the average American, is equivalent to 40 years of unavoidable exposure from natural background radiation. Model fits, both parametric and nonparametric, to the atomic-bomb data support a linear no-threshold model, below 0.1 Sv. On the basis of biologic arguments, the scientific establishment in the United States and many other countries accepts this dose-model down to zero-dose, but there is spirited dissent. The dissent may be irrelevant for developed countries, given the increase in medical diagnostic radiation that has occurred in recent decades; a sizeable percentage of this population will receive cumulative doses from the medical profession in excess of 0.1 Sv, making talk of a threshold or other sublinear response below that dose moot for future releases from nuclear facilities or a dirty bomb. The risks from both medical diagnostic doses and nuclear accident doses can be computed using the linear dose-response model, with uncertainties assigned below 0.1 Sv in a way that captures alternative scientific hypotheses. Then, the important debate over low-level radiation exposures, namely planning for accident response and weighing benefits and risks of technologies, can proceed with less distraction. One of the biggest paradoxes in the low-level radiation debate is that an individual risk can be a minor concern, while the societal risk-the total delayed cancers in an exposed population-can be of major concern.

  14. An assessment of ozone levels, UV radiation and their occupational health hazard estimation during photocopying operation.

    PubMed

    Singh, Bhupendra Pratap; Kumar, Amit; Singh, Deepak; Punia, Monika; Kumar, Krishan; Jain, Vinod Kumar

    2014-06-30

    This study investigates the levels of ozone concentration along with an ultraviolet (UV) and visible spectral radiation at eight photocopy centers in an academic institute, Delhi. Sampling was done in two types of locations, i.e., basement photocopy centers (BPC) and ground floor photocopy centers (GPC) for 8h. Measurements of levels of ozone, UV and visible radiation were done by ozone analyzer, UV radiometer and Field spectra instrument, respectively. Results show that the hourly mean concentration of ozone was observed to be in the range of 1.8-10.0 ppb and 5.3-45.8 ppb for BPC and GPC, respectively. In terms UV radiations, energy lies between 5.0×10(-3) and 7.0×10(-3) mW/cm(2) for ultraviolet A (UVA), 1.0×10(-3) and 2.0×10(-3) mW/cm(2) for ultraviolet B (UVB) and 6.0×10(-3) and 8.0×10(-3) mW/cm(2) for ultraviolet C (UVC). Correlation between the UV radiations and ozone production observed was statistically insignificant. To know the health hazard occurred to the workers, the standard erythema dose (SED) value was calculated for emitting UV radiation. The SED was estimated to be in the range of 0.02-0.04 and 0.02-0.32 for direct and indirect methods which is less than the guideline prescribed by Commission Internationale del' Eclairage (CIE). In nutshell, person involved in photocopy operation for their livelihood must be trained and should have knowledge for the long term gradual build up health problems due to ozone and UV production from photocopier. The manufactures should be ultimated with the significant ozone production, so that photocopier machine can be redesigned.

  15. Aerosols attenuating the solar radiation collected by solar tower plants: The horizontal pathway at surface level

    NASA Astrophysics Data System (ADS)

    Elias, Thierry; Ramon, Didier; Dubus, Laurent; Bourdil, Charles; Cuevas-Agulló, Emilio; Zaidouni, Taoufik; Formenti, Paola

    2016-05-01

    Aerosols attenuate the solar radiation collected by solar tower plants (STP), along two pathways: 1) the atmospheric column pathway, between the top of the atmosphere and the heliostats, resulting in Direct Normal Irradiance (DNI) changes; 2) the grazing pathway close to surface level, between the heliostats and the optical receiver. The attenuation along the surface-level grazing pathway has been less studied than the aerosol impact on changes of DNI, while it becomes significant in STP of 100 MW or more. Indeed aerosols mostly lay within the surface atmospheric layer, called the boundary layer, and the attenuation increases with the distance covered by the solar radiation in the boundary layer. In STP of 100 MW or more, the distance between the heliostats and the optical receiver becomes large enough to produce a significant attenuation by aerosols. We used measured aerosol optical thickness and computed boundary layer height to estimate the attenuation of the solar radiation at surface level at Ouarzazate (Morocco). High variabilities in aerosol amount and in vertical layering generated a significant magnitude in the annual cycle and significant inter-annual changes. Indeed the annual mean of the attenuation caused by aerosols over a 1-km heliostat-receiver distance was 3.7% in 2013, and 5.4% in 2014 because of a longest desert dust season. The monthly minimum attenuation of less than 3% was observed in winter and the maximum of more than 7% was observed in summer.

  16. Tension between reducing sea-level rise and global warming through solar-radiation management

    NASA Astrophysics Data System (ADS)

    Irvine, P. J.; Sriver, R. L.; Keller, K.

    2012-02-01

    Geoengineering using solar-radiation management (SRM) is gaining interest as a potential strategy to reduce future climate change impacts. Basic physics and past observations suggest that reducing insolation will, on average, cool the Earth. It is uncertain, however, whether SRM can reduce climate change stressors such as sea-level rise or rates of surface air temperature change. Here we use an Earth system model of intermediate complexity to quantify the possible response of sea levels and surface air temperatures to projected climate forcings and SRM strategies. We find that SRM strategies introduce a potentially strong tension between the objectives to reduce (1) the rate of temperature change and (2) sea-level rise. This tension arises primarily because surface air temperatures respond faster to radiative forcings than sea levels. Our results show that the forcing required to stop sea-level rise could cause a rapid cooling with a rate similar to the peak business-as-usual warming rate. Furthermore, termination of SRM was found to produce warming rates up to five times greater than the maximum rates under the business-as-usual CO2 scenario, whereas sea-level rise rates were only 30% higher. Reducing these risks requires a slow phase-out of many decades and thus commits future generations.

  17. Radiation environment at aviation altitudes and in space.

    PubMed

    Sihver, L; Ploc, O; Puchalska, M; Ambrožová, I; Kubančák, J; Kyselová, D; Shurshakov, V

    2015-06-01

    On the Earth, protection from cosmic radiation is provided by the magnetosphere and the atmosphere, but the radiation exposure increases with increasing altitude. Aircrew and especially space crew members are therefore exposed to an increased level of ionising radiation. Dosimetry onboard aircraft and spacecraft is however complicated by the presence of neutrons and high linear energy transfer particles. Film and thermoluminescent dosimeters, routinely used for ground-based personnel, do not reliably cover the range of particle types and energies found in cosmic radiation. Further, the radiation field onboard aircraft and spacecraft is not constant; its intensity and composition change mainly with altitude, geomagnetic position and solar activity (marginally also with the aircraft/spacecraft type, number of people aboard, amount of fuel etc.). The European Union Council directive 96/29/Euroatom of 1996 specifies that aircrews that could receive dose of >1 mSv y(-1) must be evaluated. The dose evaluation is routinely performed by computer programs, e.g. CARI-6, EPCARD, SIEVERT, PCAire, JISCARD and AVIDOS. Such calculations should however be carefully verified and validated. Measurements of the radiation field in aircraft are thus of a great importance. A promising option is the long-term deployment of active detectors, e.g. silicon spectrometer Liulin, TEPC Hawk and pixel detector Timepix. Outside the Earth's protective atmosphere and magnetosphere, the environment is much harsher than at aviation altitudes. In addition to the exposure to high energetic ionising cosmic radiation, there are microgravity, lack of atmosphere, psychological and psychosocial components etc. The milieu is therefore very unfriendly for any living organism. In case of solar flares, exposures of spacecraft crews may even be lethal. In this paper, long-term measurements of the radiation environment onboard Czech aircraft performed with the Liulin since 2001, as well as measurements and

  18. Ground-Level Ozone Following Astrophysical Ionizing Radiation Events: An Additional Biological Hazard?

    PubMed

    Thomas, Brian C; Goracke, Byron D

    2016-01-01

    Astrophysical ionizing radiation events such as supernovae, gamma-ray bursts, and solar proton events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in solar UV radiation at Earth's surface and in the upper levels of the ocean. Other work has also considered the potential impact of nitric acid rainout, concluding that no significant threat is likely. Not yet studied to date is the potential impact of ozone produced in the lower atmosphere following an ionizing radiation event. Ozone is a known irritant to organisms on land and in water and therefore may be a significant additional hazard. Using previously completed atmospheric chemistry modeling, we examined the amount of ozone produced in the lower atmosphere for the case of a gamma-ray burst and found that the values are too small to pose a significant additional threat to the biosphere. These results may be extended to other ionizing radiation events, including supernovae and extreme solar proton events.

  19. Kr-81m calibration factor for the npl ionisation chamber.

    PubMed

    Johansson, Lena; Stroak, Andrew

    2006-01-01

    A general method has been developed for the measurement of the activity concentration of 81mKr gas. Due to its short half-life, 13.1s, this gas has to be eluted from a 81Rb/81mKr generator. The 81Rb parent has a half-life of about 4.6 h. The calibration was done in two steps: firstly, a gamma-ray spectrometer was calibrated using 51Cr and 139Ce sources, nuclides with gamma-ray energies bracketing that of 81mKr (190.5 keV). The measurement geometry was equivalent to that of the 81mKr measurement; the sources were inserted into two collimated PTFE tubes in front of the gamma-ray detector. Secondly, a calibration factor for the NPL radionuclide calibrator was determined with a specially designed ionisation chamber insert. The 81mKr gas passed in front of the gamma-ray detector in PTFE tubing before and after entering the ionisation chamber. The calibration factor for 81mKr in the radionuclide calibrator with this geometry was independent of the gas flow rate within determined limits. The analytical calculations of the activity determination, uncertainties and measurement criteria are discussed.

  20. Partial ionisation cross-sections of 2-propanol and ethanal

    NASA Astrophysics Data System (ADS)

    Vacher, J. R.; Jorand, F.; Blin-Simiand, N.; Pasquiers, S.

    2006-04-01

    Electron impact ionisation of 2-propanol and ethanal is studied using mass spectrometry. Cross-sections of the formation of molecular ions and ionic fragments are measured between 14 and 86 eV. Free energy changes are evaluated using ab initio calculations. For 2-propanol, two ions, identified as CH 3CHOH + (45 amu) and CH3CHCH3+ (43 amu), contribute more than 75% to the total cross-section over the whole range of electron energies and are produced by simple bond cleavage in the molecular ion. Both processes occur spontaneously, leaving the molecular ion as a minority species. For ethanal, two ions, identified as HCO + (29 amu) and CH 3CO + (43 amu), and the molecular ion (44 amu) contribute more than 80% to the total cross-section. The ions of 29 and 43 amu result from a simple bond cleavage in the molecular ion. These sprocesses are not spontaneous and the contribution of the molecular ion becomes predominant at 15 eV and is therefore significant over the whole range of ionisation energies.

  1. Effect of radiation and age on immunoglobulin levels in rhesus monkeys (Macaca mulatta)

    SciTech Connect

    Stone, W.H.; Hackleman, S.M.; Braun, A.M.; Pennington, P.; Saphire, D.G.; Scheffler, J.; Wigle, J.C.; Cox, A.B.

    1994-06-01

    We report the results of a study on the immunoglobulin levels of rhesus monkeys (Macaca mulatta) in a colony consisting of the survivors of monkeys that received a single whole-body exposure of protons, electrons or X rays between 1964 and 1969. This colony has been maintained to assess the long-term effects of ionizing radiation on astronauts and high-flying pilots. Of the original 358 monkeys that were retained for lifetime studies, 129 (97 irradiated and 32 controls) were available for our study. We found no significant difference between the irradiated and control monkeys in mean levels of IgA, IgG and IgM, irrespective of the radiation treatment. The availability of these aged monkeys provided a unique opportunity to compare their immunoglobulin levels to those of other monkeys of various ages, and thus assess the effect of age on immunoglobulin levels. We found that only the IgA levels increase with age. 48 refs., 2 figs., 4 tabs.

  2. Diagnostic accuracy at several reduced radiation dose levels for CT imaging in the diagnosis of appendicitis

    NASA Astrophysics Data System (ADS)

    Zhang, Di; Khatonabadi, Maryam; Kim, Hyun; Jude, Matilda; Zaragoza, Edward; Lee, Margaret; Patel, Maitraya; Poon, Cheryce; Douek, Michael; Andrews-Tang, Denise; Doepke, Laura; McNitt-Gray, Shawn; Cagnon, Chris; DeMarco, John; McNitt-Gray, Michael

    2012-03-01

    Purpose: While several studies have investigated the tradeoffs between radiation dose and image quality (noise) in CT imaging, the purpose of this study was to take this analysis a step further by investigating the tradeoffs between patient radiation dose (including organ dose) and diagnostic accuracy in diagnosis of appendicitis using CT. Methods: This study was IRB approved and utilized data from 20 patients who underwent clinical CT exams for indications of appendicitis. Medical record review established true diagnosis of appendicitis, with 10 positives and 10 negatives. A validated software tool used raw projection data from each scan to create simulated images at lower dose levels (70%, 50%, 30%, 20% of original). An observer study was performed with 6 radiologists reviewing each case at each dose level in random order over several sessions. Readers assessed image quality and provided confidence in their diagnosis of appendicitis, each on a 5 point scale. Liver doses at each case and each dose level were estimated using Monte Carlo simulation based methods. Results: Overall diagnostic accuracy varies across dose levels: 92%, 93%, 91%, 90% and 90% across the 100%, 70%, 50%, 30% and 20% dose levels respectively. And it is 93%, 95%, 88%, 90% and 90% across the 13.5-22mGy, 9.6-13.5mGy, 6.4-9.6mGy, 4-6.4mGy, and 2-4mGy liver dose ranges respectively. Only 4 out of 600 observations were rated "unacceptable" for image quality. Conclusion: The results from this pilot study indicate that the diagnostic accuracy does not change dramatically even at significantly reduced radiation dose.

  3. Carcinogenesis and low-level ionizing radiation with special reference to lung cancer and exposure to radon daughters

    SciTech Connect

    Fabrikant, J.I.

    1982-04-01

    Of the important health effects of ionizing radiation, three important late effects - carcinogenesis, teratogenesis and mutagenesis are of greatest concern. This is because any exposure, even at low levels, carries some risk of such deleterious effects. As the dose of radiation increases above very low levels, the risk of health effects increases. Cancer-induction is the most important late somatic effect of low-dose ionizing radiation. Solid cancers, rather than leukemia, are principal late effects in exposed individuals. Tissues vary greatly in their susceptibility to radiation carcinogenesis. The most frequently occurring radiation-induced cancers in man include, in decreasing order of susceptibility: the female breast, the thyroid gland, the blood-forming tissues, the lung, certain organs of the gastrointestinal tract, and the bones. A number of biological and physical factors affect the cancer risk, such as age, sex, life-style, LET, and RBE. Despite uncertainty about low-level radiation risks, regulatory and advisory bodies must set standards for exposure, and individuals need information to be able to make informed judgments for themselves. From the point of view of the policy maker, the overriding concern is the fact that small doses of radiation can cause people to have more cancers than would otherwise be expected. While concern for all radiation effects exists, our human experience is limited to cancer-induction in exposed populations. This discussion is limited to cancer risk estimation and decision-making in relation to the health effects on populations of exposure to low levels of ionizing radiation. Here, low-level radiation will refer to yearly whole-body doses up to 5 rems or 0.05 Sv, or to cumulative doses up to 50 rems or 0.5 Sv from low-LET radiation and from high-LET radiation. (ERB)

  4. Measurement of the solar ultraviolet radiation at ground level in Bangi, Malaysia

    SciTech Connect

    Aljawi, Ohoud; Gopir, Geri; Duay, Abdul Basit

    2015-04-24

    Understanding the amount of ultraviolet (UV) radiation received by human, plant, and animal organisms near the earth’s surface is important to a wide range of fields such as cancer research, agriculture and forestry. The solar ultraviolet spectral irradiance at ground level was measured using the Avantes spectrometer for the period of January to March 2014 at Bangi (2°55´N, 101°46´E, 50 m above sea level) in Malaysia. These data were used to estimate the diurnal variation of UV irradiance (300 – 400 nm). The maximum irradiance of UV radiation was 45 W m{sup −2} on horizontal surface. The maximum irradiance of UV received in the local noon time, and the minimum values of UV irradiance was received in the local morning time. It is found a bigger value of UV radiation was observed on clear sky in January. The estimation of daily flux average of UV irradiance was (921± 91) kJ m{sup −2}.

  5. Measured Radiation and Background Levels During Transmission of Megawatt Electron Beams Through Millimeter Apertures

    SciTech Connect

    Alarcon, Ricardo; Balascuta, S.; Benson, Stephen V.; Bertozzi, William; Boyce, James R.; Cowan, Ray; Douglas, David R.; Evtushenko, Pavel; Fisher, P.; Ihloff, Ernest E.; Kalantarians, Narbe; Kelleher, Aidan Michael; Krossler, W. J.; Legg, Robert A.; Long, Elena; Milner, Richard; Neil, George R.; Ou, Longwu; Schmookler, Barack Abraham; Tennant, Christopher D.; Tschalar, C.; Williams, Gwyn P.; Zhang, Shukui

    2013-11-01

    We report measurements of photon and neutron radiation levels observed while transmitting a 0.43 MW electron beam through millimeter-sized apertures and during beam-off, but accelerating gradient RF-on, operation. These measurements were conducted at the Free-Electron Laser (FEL) facility of the Jefferson National Accelerator Laboratory (JLab) using a 100 MeV electron beam from an energy-recovery linear accelerator. The beam was directed successively through 6 mm, 4 mm, and 2 mm diameter apertures of length 127 mm in aluminum at a maximum current of 4.3 mA (430 kW beam power). This study was conducted to characterize radiation levels for experiments that need to operate in this environment, such as the proposed DarkLight Experiment. We find that sustained transmission of a 430 kW continuous-wave (CW) beam through a 2 mm aperture is feasible with manageable beam-related backgrounds. We also find that during beam-off, RF-on operation, multipactoring inside the niobium cavities of the accelerator cryomodules is the primary source of ambient radiation when the machine is tuned for 130 MeV operation.

  6. Measurement of the solar ultraviolet radiation at ground level in Bangi, Malaysia

    NASA Astrophysics Data System (ADS)

    Aljawi, Ohoud; Gopir, Geri; Duay, Abdul Basit

    2015-04-01

    Understanding the amount of ultraviolet (UV) radiation received by human, plant, and animal organisms near the earth's surface is important to a wide range of fields such as cancer research, agriculture and forestry. The solar ultraviolet spectral irradiance at ground level was measured using the Avantes spectrometer for the period of January to March 2014 at Bangi (2°55´N, 101°46´E, 50 m above sea level) in Malaysia. These data were used to estimate the diurnal variation of UV irradiance (300 - 400 nm). The maximum irradiance of UV radiation was 45 W m-2 on horizontal surface. The maximum irradiance of UV received in the local noon time, and the minimum values of UV irradiance was received in the local morning time. It is found a bigger value of UV radiation was observed on clear sky in January. The estimation of daily flux average of UV irradiance was (921± 91) kJ m-2.

  7. Grazing rates of Calanus finmarchicus on Thalassiosira weissflogii cultured under different levels of ultraviolet radiation.

    PubMed

    Fields, David M; Durif, Caroline M F; Bjelland, Reidun M; Shema, Steven D; Skiftesvik, Anne B; Browman, Howard I

    2011-01-01

    UVB alters photosynthetic rate, fatty acid profiles and morphological characteristics of phytoplankton. Copepods, important grazers of primary production, select algal cells based upon their size, morphological traits, nutritional status, and motility. We investigated the grazing rates of the copepod Calanus finmarchicus on the diatom Thalassiosira weissflogii cultured under 3 levels of ultraviolet radiation (UVR): photosynthetically active radiation (PAR) only (4 kJ-m(-2)/day), and PAR supplemented with UVR radiation at two intensities (24 kJ-m(-2)/day and 48 kJ-m(-2)/day). There was no significant difference in grazing rates between the PAR only treatment and the lower UVR treatment. However, grazing rates were significantly (∼66%) higher for copepods feeding on cells treated with the higher level of UVR. These results suggest that a short-term increase in UVR exposure results in a significant increase in the grazing rate of copepods and, thereby, potentially alters the flow rate of organic matter through this component of the ecosystem.

  8. Investigation of background radiation levels and geologic unit profiles in Durango, Colorado

    SciTech Connect

    Triplett, G.H. ); Foutz, W.L.; Lesperance, L.R. )

    1989-11-01

    As part of the Uranium Mill Tailings Remedial Action (UMTRA) Project, Oak Ridge National Laboratory (ORNL) has performed radiological surveys on 435 vicinity properties (VPs) in the Durango area. This study was undertaken to establish the background radiation levels and geologic unit profiles in the Durango VP area. During the months of May through June, 1986, extensive radiometric measurements and surface soil samples were collected in the Durango VP area by personnel from ORNL's Grand Junction Office. A majority of the Durango VP surveys were conducted at sites underlain by Quaternary alluvium, older Quaternary gravels, and Cretaceous Lewis and Mancos shales. These four geologic units were selected to be evaluated. The data indicated no formation anomalies and established regional background radiation levels. Durango background radionuclide concentrations in surface soil were determined to be 20.3 {plus minus} 3.4 pCi/g for {sup 40}K, 1.6 {plus minus} 0.5 pCi/g for {sup 226}Ra, and 1.2 {plus minus} 0.3 pCi/g for {sup 232}Th. The Durango background gamma exposure rate was found to be 16.5 {plus minus} 1.3 {mu}R/h. Average gamma spectral count rate measurements for {sup 40}K, {sup 226}Ra and {sup 232}Th were determined to be 553, 150, and 98 counts per minute (cpm), respectively. Geologic unit profiles and Durango background radiation measurements are presented and compared with other areas. 19 refs., 15 figs., 5 tabs.

  9. Excitotoxic and Radiation Stress Increase TERT Levels in the Mitochondria and Cytosol of Cerebellar Purkinje Neurons.

    PubMed

    Eitan, Erez; Braverman, Carmel; Tichon, Ailone; Gitler, Daniel; Hutchison, Emmette R; Mattson, Mark P; Priel, Esther

    2016-08-01

    Telomerase reverse transcriptase (TERT) is the catalytic subunit of telomerase, an enzyme that elongates telomeres at the ends of chromosomes during DNA replication. Recently, it was shown that TERT has additional roles in cell survival, mitochondrial function, DNA repair, and Wnt signaling, all of which are unrelated to telomeres. Here, we demonstrate that TERT is enriched in Purkinje neurons, but not in the granule cells of the adult mouse cerebellum. TERT immunoreactivity in Purkinje neurons is present in the nucleus, mitochondria, and cytoplasm. Furthermore, TERT co-localizes with mitochondrial markers, and immunoblot analysis of protein extracts from isolated mitochondria and synaptosomes confirmed TERT localization in mitochondria. TERT expression in Purkinje neurons increased significantly in response to two stressors: a sub-lethal dose of X-ray radiation and exposure to a high glutamate concentration. While X-ray radiation increased TERT levels in the nucleus, glutamate exposure elevated TERT levels in mitochondria. Our findings suggest that in mature Purkinje neurons, TERT is present both in the nucleus and in mitochondria, where it may participate in adaptive responses of the neurons to excitotoxic and radiation stress.

  10. Evaluation of a pulse-discharge helium ionisation detector for the determination of neon concentrations by gas chromatography.

    PubMed

    Lasa, J; Mochalski, P; Pusz, J

    2004-05-07

    A pulse-discharge helium ionisation detector, PDHID (Valco, PD-D2-I) with sample introduced to the discharge zone is shown to be applicable for reliable determinations of neon by gas chromatography. The detection level of 80 pg was obtained, but the dependence between detector response and neon mass was non-linear. However, for the discharge gas doped with 33 ppm of neon, a linear response to the neon mass up to 10(-5) g and the detection level of 0.5 ng were obtained. The method can be used for measuring neon concentrations in groundwater systems for hydrogeological purposes.

  11. Energy levels and radiative transition rates for Ge XXXI, As XXXII, and Se XXXIII

    SciTech Connect

    Aggarwal, Sunny Singh, J.; Jha, A.K.S.; Mohan, Man

    2014-07-15

    Fine-structure energies of the 67 levels belonging to the 1s{sup 2}, 1s 2l, 1s3l, 1s4l, 1s5l, and 1s6l configurations of Ge XXXI, As XXXII, and Se XXXIII have been calculated using the General-Purpose Relativistic Atomic Structure Package. In addition, radiative rates, oscillator strengths, transition wavelengths, and line strengths have been calculated for all electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among these levels. Lifetimes are also presented for all excited levels of these three ions. We have compared our results with the results available in the literature and the accuracy of the data is assessed. We predict new energy levels, oscillator strengths, and transition probabilities where no other theoretical or experimental results are available, which will form the basis for future experimental work.

  12. Microwave absorption by magnetite: a possible mechanism for coupling nonthermal levels of radiation to biological systems.

    PubMed

    Kirschvink, J L

    1996-01-01

    The presence of trace amounts of biogenic magnetite (Fe3O4) in animal and human tissues and the observation that ferromagnetic particles are ubiquitous in laboratory materials (including tissue culture media) provide a physical mechanism through which microwave radiation might produce or appear to produce biological effects. Magnetite is an excellent absorber of microwave radiation at frequencies between 0.5 and 10.0 GHz through the process of ferromagnetic resonance, where the magnetic vector of the incident field causes precession of Bohr magnetons around the internal demagnetizing field of the crystal. Energy absorbed by this process is first transduced into acoustic vibrations at the microwave carrier frequency within the crystal lattice via the magnetoacoustic effect; then, the energy should be dissipated in cellular structures in close proximity to the magnetite crystals. Several possible methods for testing this hypothesis experimentally are discussed. Studies of microwave dosimetry at the cellular level should consider effects of biogenic magnetite.

  13. Radiation doses in alternative commercial high-level waste management systems

    SciTech Connect

    Schneider, K.J.; Pelto, P.J.; Lavender, J.C.; Daling, P.M.; Fecht, B.A.

    1986-01-01

    In the commercial high-level waste management system, potential changes are being considered that will augment the benefits of an integral monitored retrievable storage (MRS) facility. The US Department of Energy (DOE) has recognized that alternative options could be implemented in the authorized waste management system (i.e., without an integral MRS facility) to potentially achieve some of the same beneficial effects of the integral MRS system. This paper summarizes those DOE-sponsored analyses related to radiation doses resulting from changes in the waste management system. This report presents generic analyses of aggregated radiation dose impacts to the public and occupational workers, of nine postulated changes in the operation of a spent-fuel management system without an MRS facility.

  14. Fused Silica Final Optics for Inertial Fusion Energy: Radiation Studies and System-Level Analysis

    SciTech Connect

    Latkowski, Jeffery F.; Kubota, Alison; Caturla, Maria J.; Dixit, Sham N.; Speth, Joel A.; Payne, Stephen A.

    2003-06-15

    The survivability of the final optic, which must sit in the line of sight of high-energy neutrons and gamma rays, is a key issue for any laser-driven inertial fusion energy (IFE) concept. Previous work has concentrated on the use of reflective optics. Here, we introduce and analyze the use of a transmissive final optic for the IFE application. Our experimental work has been conducted at a range of doses and dose rates, including those comparable to the conditions at the IFE final optic. The experimental work, in conjunction with detailed analysis, suggests that a thin, fused silica Fresnel lens may be an attractive option when used at a wavelength of 351 nm. Our measurements and molecular dynamics simulations provide convincing evidence that the radiation damage, which leads to optical absorption, not only saturates but that a 'radiation annealing' effect is observed. A system-level description is provided, including Fresnel lens and phase plate designs.

  15. Temperature rise, sea level rise and increased radiative forcing - an application of cointegration methods

    NASA Astrophysics Data System (ADS)

    Schmith, Torben; Thejll, Peter; Johansen, Søren

    2016-04-01

    We analyse the statistical relationship between changes in global temperature, global steric sea level and radiative forcing in order to reveal causal relationships. There are in this, however, potential pitfalls due to the trending nature of the time series. We therefore apply a statistical method called cointegration analysis, originating from the field of econometrics, which is able to correctly handle the analysis of series with trends and other long-range dependencies. Further, we find a relationship between steric sea level and temperature and find that temperature causally depends on the steric sea level, which can be understood as a consequence of the large heat capacity of the ocean. This result is obtained both when analyzing observed data and data from a CMIP5 historical model run. Finally, we find that in the data from the historical run, the steric sea level, in turn, is driven by the external forcing. Finally, we demonstrate that combining these two results can lead to a novel estimate of radiative forcing back in time based on observations.

  16. Impact of the 1980 BEIR-III report on low-level radiation risk assessment, radiation protection guides, and public health policy

    SciTech Connect

    Fabrikant, J.I.

    1981-06-01

    The author deals with the scientific basis for establishing appropriate radiation protection guides, and this effect on evaluation of societal activities concerned with the health effects in human populations exposed to low-level radiation. Methodology is discussed for estimating risks of radio-induced cancer and genetically related ill-health in man, the sources of data, the dose-response models used, and the precision ascribed to the process. (PSB)

  17. Effects of cell phone radiation on lipid peroxidation, glutathione and nitric oxide levels in mouse brain during epileptic seizure.

    PubMed

    Esmekaya, Meric Arda; Tuysuz, Mehmet Zahid; Tomruk, Arın; Canseven, Ayse G; Yücel, Engin; Aktuna, Zuhal; Keskil, Semih; Seyhan, Nesrin

    2016-09-01

    The objective of the this study was to evaluate the effects of cellular phone radiation on oxidative stress parameters and oxide levels in mouse brain during pentylenetetrazole (PTZ) induced epileptic seizure. Eight weeks old mice were used in the study. Animals were distributed in the following groups: Group I: Control group treated with PTZ, Group II: 15min cellular phone radiation+PTZ treatment+30min cellular phone radiation, Group III: 30min cellular phone radiation+PTZ treatment+30min cellular phone radiation. The RF radiation was produced by a 900MHz cellular phone. Lipid peroxidation, which is the indicator of oxidative stress was quantified by measuring the formation of thiobarbituric acid reactive substances (TBARS). The glutathione (GSH) levels were determined by the Ellman method. Tissue total nitric oxide (NOx) levels were obtained using the Griess assay. Lipid peroxidation and NOx levels of brain tissue increased significantly in group II and III compared to group I. On the contrary, GSH levels were significantly lower in group II and III than group I. However, no statistically significant alterations in any of the endpoints were noted between group II and Group III. Overall, the experimental findings demonstrated that cellular phone radiation may increase the oxidative damage and NOx level during epileptic activity in mouse brain.

  18. Energy deposition study of low-energy cosmic radiation at sea level

    NASA Astrophysics Data System (ADS)

    Wijesinghe, Pushpa

    In this dissertation work, a computer simulation model based on the Geant4 simulation package has been designed and developed to study the energy deposition and track structures of cosmic muons and their secondary electrons in tissue-like materials. The particle interactions in a cubic water volume were first simulated. To analyze the energy deposition and tracks in small structures, with the intention of studying the energy localization in nanometric structures such as DNA, the chamber was sliced in three dimentions. Validation studies have been performed by comparing the results with experimental, theoretical, and other simulation results to test the accuracy of the simulation model. A human body phantom in sea-level muon environment was modeled to measure the yearly dose to a human from cosmic muons. The yearly dose in this phantom is about 22 millirems. This is close to the accepted value for the yearly dose from cosmic radiation at sea level. Shielding cosmic muons with a concrete slab from 0 to 2 meters increased the dose received by the body. This dissertation presents an extensive study on the interactions of secondary electrons created by muons in water. Index words. Radiation Dosimetry Simulation, Track Structures, Sea-Level muon Flux, Energy Deposition

  19. Plasmodium falciparum: effect of radiation on levels of gene transcripts in sporozoites.

    PubMed

    Hoffman, Benjamin U; Chattopadhyay, Rana

    2008-02-01

    Humans immunized by the bites of irradiated Plasmodium falciparum (Pf) sporozoite-infected mosquitoes are protected against malaria. Radiation attenuates the sporozoites preventing them from fully developing and replicating in hepatocytes, but the effects of radiation on gene expression in sporozoites are unknown. We used RT-PCR (35 cycles of PCR followed by densitometry) to assess the expression of ten genes in Pf sporozoites, and in sporozoites irradiated with 15,000cGy. Irradiation reduced expression substantially (>60%) of two DNA repair genes; moderately (30-60%) of PfUIS3, the Pf orthologue of PbUIS3, a gene up-regulated in Plasmodium berghei sporozoites and of a third DNA repair gene; and minimally (<30%) of the Pf18S ribosomal RNA, PfCSP, PfSSP2/TRAP, and PfCELTOS genes. Irradiation increased expression of PfSPATR minimally. PfLSA1 RNA was not detectable in sporozoites. These results establish that radiation of sporozoites affects gene expression levels and provide the foundation for studies to identify specific genes involved in attenuation and protective immunity.

  20. Simultaneous Microscopic Description of Nuclear Level Density and Radiative Strength Function

    NASA Astrophysics Data System (ADS)

    Hung, N. Quang; Dang, N. Dinh; Huong, L. T. Quynh

    2017-01-01

    The nuclear level density (NLD) and radiative strength function (RSF) are simultaneously described within a microscopic approach, which takes into account the thermal effects of the exact pairing as well as the giant resonances within the phonon-damping model. The good agreement between the results of calculations and experimental data extracted by the Oslo group for 170,171,172Yb isotopes shows the importance of exact thermal pairing in the description of NLD at low and intermediate excitation energies. It also invalidates the assumption based on the Brink-Axel hypothesis in the description of the RSF.

  1. Radiative lifetime measurements of some Gd I levels by time-resolved laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Shang, Xue; Zhou, Chunxiao; Dai, Zhenwen

    2017-04-01

    Natural radiative lifetimes for 27 excited levels of Gd I in the energy range from 28215.140 to 43963.900 cm-1 were measured using time-resolved laser-induced fluorescence (TR-LIF) technique in an atom beam produced by laser-induced plasma. All the lifetimes obtained in this paper range from 8.4 to 833 ns with the uncertainties within ten percent. A comparison with a few previously reported values was performed and good agreement between them was achieved. To our best knowledge, 18 lifetimes of Gd I are reported for the first time.

  2. Non-Radiative Carrier Recombination Enhanced by Two-Level Process: A First-Principles Study

    PubMed Central

    Yang, Ji-Hui; Shi, Lin; Wang, Lin-Wang; Wei, Su-Huai

    2016-01-01

    Non-radiative recombination plays an important role in the performance of optoelectronic semiconductor devices such as solar cells and light-emitting diodes. Most textbook examples assume that the recombination process occurs through a single defect level, where one electron and one hole are captured and recombined. Based on this simple picture, conventional wisdom is that only defect levels near the center of the bandgap can be effective recombination centers. Here, we present a new two-level recombination mechanism: first, one type of carrier is captured through a defect level forming a metastable state; then the local defect configuration rapidly changes to a stable state, where the other type of carrier is captured and recombined through another defect level. This novel mechanism is applied to the recombination center in CdTe. We show that this two-level process can significantly increase the recombination rate (by three orders of magnitude) in agreement with experiments. We expect that this two-level recombination process can exist in a wide range of semiconductors, so its effect should be carefully examined in characterizing optoelectronic materials. PMID:26880667

  3. Non-radiative carrier recombination enhanced by two-level process: A first-principles study

    DOE PAGES

    Yang, Ji -Hui; Shi, Lin; Wang, Lin -Wang; ...

    2016-02-16

    In this study, non-radiative recombination plays an important role in the performance of optoelectronic semiconductor devices such as solar cells and light-emitting diodes. Most textbook examples assume that the recombination process occurs through a single defect level, where one electron and one hole are captured and recombined. Based on this simple picture, conventional wisdom is that only defect levels near the center of the bandgap can be effective recombination centers. Here, we present a new two-level recombination mechanism: first, one type of carrier is captured through a defect level forming a metastable state; then the local defect configuration rapidly changesmore » to a stable state, where the other type of carrier is captured and recombined through another defect level. This novel mechanism is applied to the recombination center Te2+cd in CdTe. We show that this two-level process can significantly increase the recombination rate (by three orders of magnitude) in agreement with experiments. We expect that this two-level recombination process can exist in a wide range of semiconductors, so its effect should be carefully examined in characterizing optoelectronic materials.« less

  4. Non-radiative carrier recombination enhanced by two-level process: A first-principles study

    SciTech Connect

    Yang, Ji -Hui; Shi, Lin; Wang, Lin -Wang; Wei, Su -Huai

    2016-02-16

    In this study, non-radiative recombination plays an important role in the performance of optoelectronic semiconductor devices such as solar cells and light-emitting diodes. Most textbook examples assume that the recombination process occurs through a single defect level, where one electron and one hole are captured and recombined. Based on this simple picture, conventional wisdom is that only defect levels near the center of the bandgap can be effective recombination centers. Here, we present a new two-level recombination mechanism: first, one type of carrier is captured through a defect level forming a metastable state; then the local defect configuration rapidly changes to a stable state, where the other type of carrier is captured and recombined through another defect level. This novel mechanism is applied to the recombination center Te2+cd in CdTe. We show that this two-level process can significantly increase the recombination rate (by three orders of magnitude) in agreement with experiments. We expect that this two-level recombination process can exist in a wide range of semiconductors, so its effect should be carefully examined in characterizing optoelectronic materials.

  5. Radiation

    NASA Video Gallery

    Outside the protective cocoon of Earth's atmosphere, the universe is full of harmful radiation. Astronauts who live and work in space are exposed not only to ultraviolet rays but also to space radi...

  6. Estimates of cosmic radiation exposure on Tunisian passenger aircraft.

    PubMed

    Zarrouk, Neïla; Bennaceur, Raouf

    2008-01-01

    Radiation field produced by cosmic radiations in the earth's atmosphere is very complex and is significantly different from that found in the nuclear industry and other environments at ground level. Aircraft crew and frequent flyers are exposed to high levels of cosmic radiations of galactic and solar origin and to secondary radiation produced in the atmosphere. Following recommendations of the International Commission on Radiological Protection in publication 60, the European Union introduced a revised Basic Safety Standard Directive, which included exposure to natural sources of ionising radiations, including cosmic radiation, as occupational exposure. We computed the dose received by some Tunisian flights, using CARI-6, EPCARD, PCAIRE, and SIEVERT codes. Calculations performed during the year 2007, on mostly regular passenger flights of the Nouvelair Tunisian Company, indicate a mean effective dose rate ranging between 3 and 4 microSv/h. We give the general background and details, focusing on the situation in Tunisia with respect to radiation protection aspects of the cosmic radiation exposure. As far as we know, such a study has not previously been carried out.

  7. TOWARDS A NOVEL MODULAR ARCHITECTURE FOR CERN RADIATION MONITORING.

    PubMed

    Boukabache, Hamza; Pangallo, Michel; Ducos, Gael; Cardines, Nicola; Bellotta, Antonio; Toner, Ciarán; Perrin, Daniel; Forkel-Wirth, Doris

    2016-11-30

    The European Organization for Nuclear Research (CERN) has the legal obligation to protect the public and the people working on its premises from any unjustified exposure to ionising radiation. In this context, radiation monitoring is one of the main concerns of the Radiation Protection Group. After 30 y of reliable service, the ARea CONtroller (ARCON) system is approaching the end of its lifecycle, which raises the need for new, more efficient radiation monitors with a high level of modularity to ensure better maintainability. Based on these two main principles, new detectors are currently being developed that will be capable of measuring very low dose rates down to 50 nSv h(-1), whilst being able to measure radiation over an extensive range of 8 decades without any auto scaling. To reach these performances, CERN Radiation MOnitoring Electronics (CROME), the new generation of CERN radiation monitors, is based on the versatile architecture that includes new read-out electronics developed by the Instrumentation and Logistics section of the CERN Radiation Protection Group as well as a reconfigurable system on chip capable of performing complex processing calculations. Beside the capabilities of CROME to continuously measure the ambient dose rate, the system generates radiation alarms, provides interlock signals, drives alarm display units through a fieldbus and provides long-term, permanent and reliable data logging. The measurement tests performed during the first phase of the development show very promising results that pave the way to the second phase: the certification.

  8. Electron impact ionisation cross sections of iron hydrogen clusters

    NASA Astrophysics Data System (ADS)

    Huber, Stefan E.; Sukuba, Ivan; Urban, Jan; Limtrakul, Jumras; Probst, Michael

    2016-09-01

    We computed electron impact ionisation cross sections (EICSs) of iron hydrogen clusters, FeH n with n = 1,2, ...,10, from the ionisation threshold to 10 keV using the Deutsch-Märk (DM) and the binary-encounter-Bethe (BEB) formalisms. The maxima of the cross sections for the iron hydrogen clusters range from 6.13 × 10-16 cm2 at 60 eV to 8.76 × 10-16 cm2 at 76 eV for BEB-AE (BEB method based on quantum-chemical data from all-electron basis sets) calculations, from 4.15 × 10-16 cm2 at 77 eV to 7.61 × 10-16 cm2 at 80 eV for BEB-ECP (BEB method based on quantum-chemical data from effective-core potentials for inner-core electrons) calculations and from 2.49 × 10-16 cm2 at 43.5 eV to 7.04 × 10-16 cm2 at 51 eV for the DM method. Cross sections calculated via the BEB method are substantially higher than the ones obtained via the DM method, up to a factor of about two for FeH and FeH2. The formation of Fe-H bonds depopulates the iron 4 s orbital, causing significantly lower cross sections for the small iron hydrides compared to atomic iron. Both the DM and BEB cross sections can be fitted perfectly against a simple expression used in modelling and simulation codes in the framework of nuclear fusion research. The energetics of the iron hydrogen clusters change substantially when exact exchange is present in the density functional, while the cluster geometries do not depend on this choice.

  9. Modulation of DNA methylation levels sensitizes doxorubicin-resistant breast adenocarcinoma cells to radiation-induced apoptosis

    SciTech Connect

    Luzhna, Lidia; Kovalchuk, Olga

    2010-02-05

    Chemoresistant tumors often fail to respond to other cytotoxic treatments such as radiation therapy. The mechanisms of chemo- and radiotherapy cross resistance are not fully understood and are believed to be epigenetic in nature. We hypothesize that MCF-7 cells and their doxorubicin-resistant variant MCF-7/DOX cells may exhibit different responses to ionizing radiation due to their dissimilar epigenetic status. Similar to previous studies, we found that MCF-7/DOX cells harbor much lower levels of global DNA methylation than MCF-7 cells. Furthermore, we found that MCF-7/DOX cells had lower background apoptosis levels and were less responsive to radiation than MCF-7 cells. Decreased radiation responsiveness correlated to significant global DNA hypomethylation in MCF-7/DOX cells. Here, for the first time, we show that the radiation resistance of MCF-7/DOX cells can be reversed by an epigenetic treatment - the application of methyl-donor SAM. SAM-mediated reversal of DNA methylation led to elevated radiation sensitivity in MCF-7/DOX cells. Contrarily, application of SAM on the radiation sensitive and higher methylated MCF-7 cells resulted in a decrease in their radiation responsiveness. This data suggests that a fine balance of DNA methylation is needed to insure proper radiation and drug responsiveness.

  10. A large-scale measurement, analysis and modelling of electromagnetic radiation levels in the vicinity of GSM/UMTS base stations in an urban area.

    PubMed

    Karadağ, Teoman; Yüceer, Mehmet; Abbasov, Teymuraz

    2016-01-01

    The present study analyses the electric field radiating from the GSM/UMTS base stations located in central Malatya, a densely populated urban area in Turkey. The authors have conducted both instant and continuous measurements of high-frequency electromagnetic fields throughout their research by using non-ionising radiation-monitoring networks. Over 15,000 instant and 13,000,000 continuous measurements were taken throughout the process. The authors have found that the normal electric field radiation can increase ∼25% during daytime, depending on mobile communication traffic. The authors' research work has also demonstrated the fact that the electric field intensity values can be modelled for each hour, day or week with the results obtained from continuous measurements. The authors have developed an estimation model based on these values, including mobile communication traffic (Erlang) values obtained from mobile phone base stations and the temperature and humidity values in the environment. The authors believe that their proposed artificial neural network model and multivariable least-squares regression analysis will help predict the electric field intensity in an environment in advance.

  11. Seasonal Variation in Exposure Level of Types A and B Ultraviolet Radiation: An Environmental Skin Carcinogen

    PubMed Central

    Rafieepour, A; Ghamari, F; Mohammadbeigi, A; Asghari, M

    2015-01-01

    Background: The main source of ultraviolet radiation (UVR) is the sun, affecting organs such as the skin, eyes, and immune system. According to American Conference of Governmental Industrial Hygienist (ACGIH) reports, the amount of UVR reaching the Earth's surface is increasing yearly and is responsible for an increase in solar radiation-related diseases. Aims: To investigate the amount of UVR reaching the Earth's surface and understand the risk of UVR on disease among outdoor laborers in one of the central provinces of Iran. Materials and Methods: Arak city was divided into two geographic areas, and the weekly measurement of UVR was done in three locations) asphalt, grass and rooftop). To measure UVR, Hanger UV spectrometer, standard deviation (SD8-A), and SD8-B detectors were used. Amounts of UVR for a consecutive year and varying weather conditions were measured. Finally, values obtained were compared to ACGIH standards. Results: The minimum and maximum levels of UV type A radiation occurred in April 1.27 (0.724) W/m2 and September 7.147 (4.128) W/m2, these figures for UV type B were in March–April 0.005 (0.003) and September 0.083 (0.077). The maximum UVR is received between 11 and 15 o’clock. Conclusions: In the central cities of Iran, the minimum and maximum UV type A and B is received in March–April and in September, respectively. Based on the results, the angular position of the sun in the sky, cloud cover, and height from ground level affected the amount of UVR received, but the geographic locations studied did not. PMID:25861533

  12. Environmental radiation monitoring of low-level wastes by the State of Washington

    SciTech Connect

    Conklin, A.W.; Mooney, R.R.; Erickson, J.L.

    1989-11-01

    The Washington State Department of Health, as the state`s regulatory agency for radiation, monitors several forms of low-level radioactive wastes. The monitoring is done to assess the potential impact on the environment and on public health. The emphasis of the monitoring program is placed on the solid and liquid wastes from defense activities on the Hanford Reservation, commercial wastes at the site located on leased land at Hanford and uranium mill tailings in Northeastern Washington. Although not classified as low-level waste, monitoring is also periodically conducted at selected landfills and sewage treatment facilities and other licensees, where radioactive wastes are known or suspected to be present. Environmental pathways associated with waste disposal are monitored independently, and/or in conjunction with the waste site operators to verify their results and evaluate their programs. The Department also participates in many site investigations conducted by site operators and other agencies, and conducts it`s own special investigations when deemed necessary. Past investigations and special projects have included allegations of adverse environmental impact of I-129, uranium in ground water, impacts of wastes on the agricultural industry, radioactivity in seeps into the Columbia River from waste sites, identifying lost waste sites at Hanford, differentiating groundwater contamination from defense versus commercial sources, and radioactivity in municipal landfills and sewers. The state`s environmental radiation monitoring program has identified and verified a number of environmental problems associated with radioactive waste disposal, but has, to date, identified no adverse offsite impacts to public health.

  13. Measurement of soil radioactivity levels and radiation hazard assessment in southern Rechna interfluvial region, Pakistan.

    PubMed

    Jabbar, Abdul; Arshed, Waheed; Bhatti, Arshad Saleem; Ahmad, Syed Salman; Akhter, Perveen; Rehman, Saeed-Ur; Anjum, Muhammad Iftikhar

    2010-10-01

    Rechna interfluvial region is one of the main regions of Punjab, Pakistan. It is the area which is lying between River Ravi and River Chenab, alluvial-filled. Radioactivity levels in soil samples, collected from southern Rechna interfluvial region, Pakistan, have been estimated by using gamma-ray spectrometric technique. (226)Ra, (232)Th, the primordial radionuclide (40)K, and the artificial radionuclide (137)Cs have been measured in the soil of the study area. The mean radioactivity levels of (226)Ra, (232)Th, (40)K, and (137)Cs were found to be 50.6 +/- 1.7, 62.3 +/- 3.2, 662.2 +/- 32.1, and 3.1 +/- 0.3 Bq kg(-1), respectively. The mean radium equivalent activity (Ra(eq)), outdoor radiation hazard index (H(out)), indoor radiation hazard index (H(in)), and terrestrial absorbed dose rate for the area under study were determined as 190.8 +/- 8.7 Bq kg(-1), 0.52, 0.65, and 69.8 nGy h(-1), respectively. The annual effective dose to the general public was found to be 0.43 mSv. This value lies well below the limit of 1 mSv for general public as recommended by the International Commission on Radiological Protection. The measured values are comparable with other global radioactivity measurements and are found to be safe for the public and the environment.

  14. Improving the Fermilab Booster Notching Efficiency, Beam Losses and Radiation Levels

    SciTech Connect

    Rakhno, I.L.; Drozhdin, A.I.; Mokhov, N.V.; Sidorov, V.I.; Tropin, I.S.; /Fermilab

    2012-05-14

    A fast vertical 1.08-m long kicker (notcher) located in the Fermilab Booster Long-05 straight section is currently used to remove 3 out of 84 circulating bunches after injection to generate an abort gap. With the maximum magnetic field of 72.5 Gauss, it removes only 87% of the 3-bunch intensity at 400 MeV, with 75% loss on pole tips of the focusing Booster magnets, 11% on the Long-06 collimators, and 1% in the rest of the ring. We propose to improve the notching efficiency and reduce beam loss in the Booster by using three horizontal kickers in the Long-12 section. STRUCT calculations show that using horizontal notchers, one can remove up to 96% of the 3-bunch intensity at 400-700 MeV, directing 95% of it to a new beam dump at the Long-13 section. This fully decouples notching and collimation. The beam dump absorbs most of the impinging proton energy in its jaws. The latter are encapsulated into an appropriate radiation shielding that reduces impact on the machine components, personnel and environment to the tolerable levels. MARS simulations show that corresponding prompt and residual radiation levels can be reduced ten times compared to the current ones.

  15. Assessment of natural radioactivity levels and radiation hazards due to cement industry.

    PubMed

    El-Taher, A; Makhluf, S; Nossair, A; Abdel Halim, A S

    2010-01-01

    The cement industry is considered as one of the basic industries that plays an important role in the national economy of developing countries. Activity concentrations of (226)Ra, (232)Th and (40)K in Assiut cement and other local cement types from different Egyptian factories has been measured by using gamma-ray spectrometry. From the measured gamma-ray spectra, specific activities were determined. The measured activity concentrations for these natural radionuclides were compared with the reported data for other countries. The average values obtained for (226)Ra, (232)Th and (40)K activity concentration in different types of cement are lower than the corresponding global values reported in UNSCEAR publications. The obtained results show that the averages of radiation hazard parameters for Assiut cement factory are lower than the acceptable level of 370Bqkg(-1) for radium equivalent Ra(eq), 1 for level index Igammar, the external hazard index Hex radiation hazard parameters. Cement does not pose a significant radiological hazard when used for construction of buildings.

  16. Radiation-induced cardiovascular effects

    NASA Astrophysics Data System (ADS)

    Tapio, Soile

    Recent epidemiological studies indicate that exposure to ionising radiation enhances the risk of cardiovascular mortality and morbidity in a moderate but significant manner. Our goal is to identify molecular mechanisms involved in the pathogenesis of radiation-induced cardiovascular disease using cellular and mouse models. Two radiation targets are studied in detail: the vascular endothelium that plays a pivotal role in the regulation of cardiac function, and the myocardium, in particular damage to the cardiac mitochondria. Ionising radiation causes immediate and persistent alterations in several biological pathways in the endothelium in a dose- and dose-rate dependent manner. High acute and cumulative doses result in rapid, non-transient remodelling of the endothelial cytoskeleton, as well as increased lipid peroxidation and protein oxidation of the heart tissue, independent of whether exposure is local or total body. Proteomic and functional changes are observed in lipid metabolism, glycolysis, mitochondrial function (respiration, ROS production etc.), oxidative stress, cellular adhesion, and cellular structure. The transcriptional regulators Akt and PPAR alpha seem to play a central role in the radiation-response of the endothelium and myocardium, respectively. We have recently started co-operation with GSI in Darmstadt to study the effect of heavy ions on the endothelium. Our research will facilitate the identification of biomarkers associated with adverse cardiac effects of ionising radiation and may lead to the development of countermeasures against radiation-induced cardiac damage.

  17. Underwater radiated noise levels of a research icebreaker in the central Arctic Ocean.

    PubMed

    Roth, Ethan H; Schmidt, Val; Hildebrand, John A; Wiggins, Sean M

    2013-04-01

    U.S. Coast Guard Cutter Healy's underwater radiated noise signature was characterized in the central Arctic Ocean during different types of ice-breaking operations. Propulsion modes included transit in variable ice cover, breaking heavy ice with backing-and-ramming maneuvers, and dynamic positioning with the bow thruster in operation. Compared to open-water transit, Healy's noise signature increased approximately 10 dB between 20 Hz and 2 kHz when breaking ice. The highest noise levels resulted while the ship was engaged in backing-and-ramming maneuvers, owing to cavitation when operating the propellers astern or in opposing directions. In frequency bands centered near 10, 50, and 100 Hz, source levels reached 190-200 dB re: 1 μPa at 1 m (full octave band) during ice-breaking operations.

  18. Energy levels, radiative rates, and lifetimes for transitions in W XL

    SciTech Connect

    Aggarwal, Kanti M. Keenan, Francis P.

    2014-11-15

    Energy levels and radiative rates are reported for transitions in Br-like tungsten, W XL, calculated with the general-purpose relativistic atomic structure package (GRASP). Configuration interaction (CI) has been included among 46 configurations (generating 4215 levels) over a wide energy range up to 213 Ryd. However, for conciseness results are only listed for the lowest 360 levels (with energies up to ∼43 Ryd), which mainly belong to the 4s{sup 2}4p{sup 5},4s{sup 2}4p{sup 4}4d,4s{sup 2}4p{sup 4}4f,4s4p{sup 6},4p{sup 6}4d,4s4p{sup 5}4d,4s{sup 2}4p{sup 3}4d{sup 2}, and 4s{sup 2}4p{sup 3}4d4f configurations, and provided for four types of transitions, E1, E2, M1, and M2. Comparisons are made with existing (but limited) results. However, to fully assess the accuracy of our data, analogous calculations have been performed with the flexible atomic code, including an even larger CI than in GRASP. Our energy levels are estimated to be accurate to better than 0.02 Ryd, whereas results for radiative rates (and lifetimes) should be accurate to better than 20% for a majority of the strong transitions.

  19. Differential ionisation of natural antioxidant polyenes in electrospray and nanospray mass spectrometry.

    PubMed

    Guaratini, Thais; Gates, Paul J; Pinto, Ernani; Colepicolo, Pio; Lopes, Norberto P

    2007-01-01

    Carotenoids are natural products with high economic relevance for the pharmaceutical industries and are a common subject for biochemical research. Reported here is a comparative study of the ionisation of carotenoids by electrospray mass spectrometry (ESI-MS) and nanospray mass spectrometry (nanoESI-MS). The results demonstrate that, along with solvent choice, the influence of the different ionisation processes of ESI and nanoESI are fundamental in determining how ionisation is achieved and which ions (molecular ion or protonated molecule) are observed in MS. The increased understanding afforded by this study will help in the development of unequivocal microanalytical methods for carotenoids and related antioxidant polyenes.

  20. Ionisation effect on the electron localisation in the subcycle waveform shaping scheme

    NASA Astrophysics Data System (ADS)

    Wang, Zhuo; Feng, Zhengpeng; Long, Hua

    2015-03-01

    We have theoretically studied the ionisation effect on the asymmetric dissociation of H+2 exposed to the synthesised multicycle infrared pulses of different wavelengths by solving the time-dependent Schr?dinger equation without using the Born-Oppenheimer approximation. It has been demonstrated that the ionisation does slightly influence the electron localisation for the relatively low pulse intensity (less than 1014 W/cm2). However, our further results show that the ionisation effect becomes much more significant when increasing the pulse intensity, leading to a distinctly different mechanism responsible for the enhancement of the electron localisation.

  1. A miniaturised laser ablation/ionisation analyser for investigation of elemental/isotopic composition with the sub-ppm detection sensitivity

    NASA Astrophysics Data System (ADS)

    Tulej, M.; Riedo, A.; Meyer, S.; Iakovleva, M.; Neuland, M.; Wurz, P.

    2012-04-01

    analysis of solid materials on the planetary surfaces (Rohner et al., 2003). Initial laboratory tests that were conducted with an IR laser radiation for the ablation, atomisation and ionisation of the material, indicated a high performance of the instrument in terms of sensitivity, dynamic range and mass resolution (Tulej et al., 2011). After some technical improvements and implementation of a computer-controlled performance optimiser we have achieved further improvements of both, the instrumental sensitivity down to sub-ppm level and reproducibility of the measurements. We will demonstrate the potential of the mass analyser to perform the quantitative elemental analysis of solids with a spatial (vertical, lateral) resolution commensurate with typical grain sizes, and its capabilities for investigation of isotopic patterns with accuracy and precision comparable to that of large analytical laboratory instruments, e.g., TIMS, SIMS, LA-ICP-MS. The results can be of considerable interest for in situ dating or investigation of other fine isotopic fractionation effects including studies of bio-markers.

  2. MO-C-18C-01: Radiation Risks at Level of Few CT Scans: How Real?- Science to Practice

    SciTech Connect

    Rehani, M; Samei, E; Morgan, W; Goske, M; Shore, R

    2014-06-15

    There are controversies surrounding radiation effects in human population in the range of radiation doses encountered by patients resulting from one to several CT scans. While it is understandable why the effects from low levels of diagnostic radiation are controversial, the situation is complicated by the media which may distort the known facts. There is need to understand the state of science regarding low-level radiation effects and also to understand how to communicate the potential risk with patients, the public and media. This session will seek to come to a consensus in order to speak with one voice to the media and the public. This session will review radiation effects known so far from a variety of exposed groups since the nuclear holocaust, provide clarification where effects are certain and where they are not, at what level extrapolation is the only way and at what level there is weak but agreeable acceptance. We will depict where and why there is agreement among organizations responsible for studying radiation effects, and how to deal with situations where effects are uncertain. Specific focus on radiation effects in children will be provided.Finally, the session will attempt to bridge the communication gap from the science to how to be an effective communicator with patients, parents, and media about ionizing radiation. Learning Objectives: To have a clear understanding about certainties and uncertainties of radiation effects at the level of a few CT scans To understand the results and limitations from 3 major pediatric CT scientific studies on childhood exposures published recently. To understand successful strategies used in risk communication.

  3. Secondary ionisations in a wall-less ion-counting nanodosimeter: quantitative analysis and the effect on the comparison of measured and simulated track structure parameters in nanometric volumes

    NASA Astrophysics Data System (ADS)

    Hilgers, Gerhard; Bug, Marion U.; Gargioni, Elisabetta; Rabus, Hans

    2015-10-01

    The object of investigation in nanodosimetry is the physical characteristics of the microscopic structure of ionising particle tracks, i.e. the sequence of the interaction types and interaction sites of a primary particle and all its secondaries, which reflects the stochastic nature of the radiation interaction. In view of the upcoming radiation therapy with protons and carbon ions, the ionisation structure of the ion track is of particular interest. Owing to limitations in current detector technology, the only way to determine the ionisation cluster size distribution in a DNA segment is to simulate the particle track structure in condensed matter. This is done using dedicated computer programs based on Monte Carlo procedures simulating the interaction of the primary ions with the target. Hence, there is a need to benchmark these computer codes using suitable experimental data. Ionisation cluster size distributions produced in the nanodosimeter's sensitive volume by monoenergetic protons and alpha particles (with energies between 0.1 MeV and 20 MeV) were measured at the PTB ion accelerator facilities. C3H8 and N2 were alternately used as the working gas. The measured data were compared with the simulation results obtained with the PTB Monte-Carlo code PTra [B. Grosswendt, Radiat. Environ. Biophys. 41, 103 (2002); M.U. Bug, E. Gargioni, H. Nettelbeck, W.Y. Baek, G. Hilgers, A.B. Rosenfeld, H. Rabus, Phys. Rev. E 88, 043308 (2013)]. Measured and simulated characteristics of the particle track structure are generally in good agreement for protons over the entire energy range investigated. For alpha particles with energies higher than the Bragg peak energy, a good agreement can also be seen, whereas for energies lower than the Bragg peak energy differences of as much as 25% occur. Significant deviations are only observed for large ionisation cluster sizes. These deviations can be explained by a background consisting of secondary ions. These ions are produced in the

  4. Creating a strategy for science-based national policy: Addressing conflicting views on the health risk of low-level ionizing radiation. Final report, Wingspread Conference

    SciTech Connect

    McClellan, Roger O.; Apple, Martin A.

    1998-03-03

    Significant cancer risk for adults exposed to more than 100 millisieverts (10 REM) of ionizing radiation. More research on low-level ionizing radiation is needed in molecular and cellular mechanisms of injury and ongoing exposed populations. Implementation costs should be considered in regulating low-level ionizing radiation. Comparative risk assessment is a powerful tool for risk-based policy formation, and conflicting legal statutes should become harmonized for radiation regulation. More public dialog on low-level radiation is needed. A high level commission should evaluate radiation hazard control practices.

  5. Electrochromic Radiator Coupon Level Testing and Full Scale Thermal Math Modeling for Use on Altair Lunar Lander

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik; Bannon, Erika; Bower, Chad

    2009-01-01

    In order to control system and component temperatures, many spacecraft thermal control systems use a radiator coupled with a pumped fluid loop to reject waste heat from the vehicle. Since heat loads and radiation environments can vary considerably according to mission phase, the thermal control system must be able to vary the heat rejection. The ability to "turn down" the heat rejected from the thermal control system is critically important when designing the system.. Electrochromic technology as a radiator coating is being investigated to vary the amount of heat being rejected by a radiator. Coupon level tests were performed to test the feasibility of the technology. Furthermore, thermal math models were developed to better understand the turndown ratios required by full scale radiator architectures to handle the various operation scenarios during a mission profile for Altair Lunar Lander. This paper summarizes results from coupon level tests as well as thermal math models developed to investigate how electrochromics can be used to provide the largest turn down ratio for a radiator. Data from the various design concepts of radiators and their architectures are outlined. Recommendations are made on which electrochromic radiator concept should be carried further for future thermal vacuum testing.

  6. Electrochromic Radiator Coupon Level Testing and Full Scale Thermal Math Modeling for Use on Altair Lunar Lander

    NASA Technical Reports Server (NTRS)

    Bannon, Erika T.; Bower, Chad E.; Sheth, Rubik; Stephan, Ryan

    2010-01-01

    In order to control system and component temperatures, many spacecraft thermal control systems use a radiator coupled with a pumped fluid loop to reject waste heat from the vehicle. Since heat loads and radiation environments can vary considerably according to mission phase, the thermal control system must be able to vary the heat rejection. The ability to "turn down" the heat rejected from the thermal control system is critically important when designing the system. Electrochromic technology as a radiator coating is being investigated to vary the amount of heat rejected by a radiator. Coupon level tests were performed to test the feasibility of this technology. Furthermore, thermal math models were developed to better understand the turndown ratios required by full scale radiator architectures to handle the various operation scenarios encountered during a mission profile for the Altair Lunar Lander. This paper summarizes results from coupon level tests as well as the thermal math models developed to investigate how electrochromics can be used to increase turn down ratios for a radiator. Data from the various design concepts of radiators and their architectures are outlined. Recommendations are made on which electrochromic radiator concept should be carried further for future thermal vacuum testing.

  7. Trade Study of System Level Ranked Radiation Protection Concepts for Deep Space Exploration

    NASA Technical Reports Server (NTRS)

    Cerro, Jeffrey A

    2013-01-01

    A strategic focus area for NASA is to pursue the development of technologies which support exploration in space beyond the current inhabited region of low earth orbit. An unresolved issue for crewed deep space exploration involves limiting crew radiation exposure to below acceptable levels, considering both solar particle events and galactic cosmic ray contributions to dosage. Galactic cosmic ray mitigation is not addressed in this paper, but by addressing credible, easily implemented, and mass efficient solutions for the possibility of solar particle events, additional margin is provided that can be used for cosmic ray dose accumulation. As a result, NASA s Advanced Engineering Systems project office initiated this Radiation Storm Shelter design activity. This paper reports on the first year results of an expected 3 year Storm Shelter study effort which will mature concepts and operational scenarios that protect exploration astronauts from solar particle radiation events. Large trade space definition, candidate concept ranking, and a planned demonstration comprised the majority of FY12 activities. A system key performance parameter is minimization of the required increase in mass needed to provide a safe environment. Total system mass along with operational assessments and other defined protection system metrics provide the guiding metrics to proceed with concept developments. After a downselect to four primary methods, the concepts were analyzed for dosage severity and the amount of shielding mass necessary to bring dosage to acceptable values. Besides analytical assessments, subscale models of several concepts and one full scale concept demonstrator were created. FY12 work terminated with a plan to demonstrate test articles of two selected approaches. The process of arriving at these selections and their current envisioned implementation are presented in this paper.

  8. Effects of low-level radiation upon the hematopoietic steam cell: implications for leukemogenesis

    SciTech Connect

    Cronkite, E.P.; Bond, V.P.; Carsten, A.L.; Miller, M.E.; Bullis, J.E.

    1983-01-01

    These studies have addressed firstly the effect of single small doses of x-ray upon murine hematopoietic stem cells to obtain a better estimate of the D/sub q/. It is small, of the order of 20 rads. Secondly, a dose fractionation schedule tht does not kill or perturb the kinetics of hemopoietic cell proliferation was sought in order to investigate the leukemogenic potential of low level radiation upon an unperturbed hemopoietic system. The studies reported herein show tht 1.25 rads every other day decrease the CFU-S content of bone marrow by the time 40 rads are accumulated. Studies on the effect of 0.5, 1.0, 2.0, and 3.0 rads 3 times per week are under way. Two rads 3 times per week produced a modest decrease in CFU-S content of bone marrow after an accumulation of 68 rads. With 3.0 rads 3 times per week an accumulation of 102 rads produces a significant decrease in CFU-S content of bone marrow. Dose fractionation at 0.5 and 1.0 rad 3 times per week has not produced a CFU-S depression after accumulation of 17 and 34 rads. Radiation leukemogenesis studies published to date have utilized single doses and chronic exposure schedules that probably have significantly perturbed the kinetics of hematopoietic stem cells. Whether radiation will produce leukemia in animal models with dose schedules that do not perturb kinetics of hematopoietic stem cells remains to be seen.

  9. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) Provides Accurate Direct from Culture Species Identification within the Genus Candida.

    PubMed

    Cameron, Simon J S; Bolt, Frances; Perdones-Montero, Alvaro; Rickards, Tony; Hardiman, Kate; Abdolrasouli, Alireza; Burke, Adam; Bodai, Zsolt; Karancsi, Tamas; Simon, Daniel; Schaffer, Richard; Rebec, Monica; Balog, Julia; Takáts, Zoltan

    2016-11-14

    Members of the genus Candida, such as C. albicans and C. parapsilosis, are important human pathogens. Other members of this genus, previously believed to carry minimal disease risk, are increasingly recognised as important human pathogens, particularly because of variations in susceptibilities to widely used anti-fungal agents. Thus, rapid and accurate identification of clinical Candida isolates is fundamental in ensuring timely and effective treatments are delivered. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) has previously been shown to provide a high-throughput platform for the rapid and accurate identification of bacterial and fungal isolates. In comparison to commercially available matrix assisted laser desorption ionisation time of flight mass spectrometry (MALDI-ToF), REIMS based methods require no preparative steps nor time-consuming cell extractions. Here, we report on the ability of REIMS-based analysis to rapidly and accurately identify 153 clinical Candida isolates to species level. Both handheld bipolar REIMS and high-throughput REIMS platforms showed high levels of species classification accuracy, with 96% and 100% of isolates classified correctly to species level respectively. In addition, significantly different (FDR corrected P value < 0.05) lipids within the 600 to 1000 m/z mass range were identified, which could act as species-specific biomarkers in complex microbial communities.

  10. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) Provides Accurate Direct from Culture Species Identification within the Genus Candida

    PubMed Central

    Cameron, Simon J. S.; Bolt, Frances; Perdones-Montero, Alvaro; Rickards, Tony; Hardiman, Kate; Abdolrasouli, Alireza; Burke, Adam; Bodai, Zsolt; Karancsi, Tamas; Simon, Daniel; Schaffer, Richard; Rebec, Monica; Balog, Julia; Takáts, Zoltan

    2016-01-01

    Members of the genus Candida, such as C. albicans and C. parapsilosis, are important human pathogens. Other members of this genus, previously believed to carry minimal disease risk, are increasingly recognised as important human pathogens, particularly because of variations in susceptibilities to widely used anti-fungal agents. Thus, rapid and accurate identification of clinical Candida isolates is fundamental in ensuring timely and effective treatments are delivered. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) has previously been shown to provide a high-throughput platform for the rapid and accurate identification of bacterial and fungal isolates. In comparison to commercially available matrix assisted laser desorption ionisation time of flight mass spectrometry (MALDI-ToF), REIMS based methods require no preparative steps nor time-consuming cell extractions. Here, we report on the ability of REIMS-based analysis to rapidly and accurately identify 153 clinical Candida isolates to species level. Both handheld bipolar REIMS and high-throughput REIMS platforms showed high levels of species classification accuracy, with 96% and 100% of isolates classified correctly to species level respectively. In addition, significantly different (FDR corrected P value < 0.05) lipids within the 600 to 1000 m/z mass range were identified, which could act as species-specific biomarkers in complex microbial communities. PMID:27841356

  11. Parameterization of the level-resolved radiative recombination rate coefficients for the SPEX code

    NASA Astrophysics Data System (ADS)

    Mao, Junjie; Kaastra, Jelle

    2016-03-01

    The level-resolved radiative recombination (RR) rate coefficients for H-like to Na-like ions from H (Z = 1) up to and including Zn (Z = 30) are studied here. For H-like ions, the quantum-mechanical exact photoionization cross sections for nonrelativistic hydrogenic systems are usedto calculate the RR rate coefficients under the principle of detailed balance, while for He-like to Na-like ions, the archival data on ADAS are adopted. Parameterizations are made for the direct capture rates in a wide temperature range. The fitting accuracies are better than 5% for about 99% of the ~3 × 104 levels considered here. The ~1% exceptions include levels from low-charged many-electron ions, and/or high-shell (n ≳ 4) levels are less important in terms of interpreting X-ray emitting astrophysical plasmas. The RR data will be incorporated into the high-resolution spectral analysis package SPEX. Results of the parameterizations are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A84

  12. Ground level photosynthetically active radiation dynamics in stands of Acacia mearnsii De Wild.

    PubMed

    Péllico Netto, Sylvio; Sanquetta, Carlos R; Caron, Braulio O; Behling, Alexandre; Simon, Augusto A; Corte, Ana Paula D; Bamberg, Rogério

    2015-09-01

    The objective is to study the dynamics of photosynthetic radiation reaching the soil surface in stands of Acacia mearnsii De Wild and its influence on height growth in stands. This fact gives rise to the formulation of the following hypothesis for this study: "The reduction of the incidence of light inside the stand of black wattle will cause the inflection point in its height growth when this reaches 4 to 5 m in height, i.e. when the stand is between 2 and 3 years of age". The study was conducted in stands in the state of Rio Grande do Sul, Brazil, where diameters at breast height, total height and photosynthetically active radiation available at ground level were measured. The frequency tended to be more intense when the age of the stands increases. It was evident that a reduction of light incidence inside the forest occurred, caused by canopy closure. Consequently, closed canopy propitiated the competition of plants. This has affected the conditions for growth in diameter and height of this species, reason why it becomes possible to conceive the occurrence of an inflection point in the growth of these two variables, confirming the formulated hypothesis.

  13. Conceptual basis for evaluating risk from low-level radiation exposure

    SciTech Connect

    Bond, V.P.

    1981-01-01

    Serious or lethal injuries that may result from the exposure of animals or human beings to ionizing radiations can be divided into two distinctly different categories, on the basis of whether the injury results only from failure of an entire vital organ, or stems from impairment of the function of a single cell. These two categories of injury are termed here organ effects, normally induced by non-stochastic processes, and single cell effects, normally induced by stochastic processes. This presentation is limited to low-level radiation exposure (LLR) since: (1) only with single hit kinetics does the average number of cell doses per cell in the exposed population essentially equal the number of cells dosed; (2) in excluding multihit all-or-none effects, the functions developed are essentially independent of the time rate at which the (instantaneously deposited) cell doses are laid down, and of considerations of repair of sub-effect injury; and (3) it makes little or no difference with LLR if the incidence of single cell effects is expressed in terms of exposed or surviving cells.

  14. Radiation safety concerns and diagnostic reference levels for computed tomography scanners in Tamil Nadu.

    PubMed

    Livingstone, Roshan S; Dinakaran, Paul M

    2011-01-01

    Radiation safety in computed tomography (CT) scanners is of concern due its widespread use in the field of radiological imaging. This study intends to evaluate radiation doses imparted to patients undergoing thorax, abdomen and pelvic CT examinations and formulate regional diagnostic reference levels (DRL) in Tamil Nadu, South India. In-site CT dose measurement was performed in 127 CT scanners in Tamil Nadu for a period of 2 years as a part of the Atomic Energy Regulatory Board (AERB)-funded project. Out of the 127 CT scanners,13 were conventional; 53 single-slice helical scanners (SSHS); 44 multislice CT (MSCT) scanners; and 17 refurbished scanners. CT dose index (CTDI) was measured using a 32-cm polymethyl methacrylate (PMMA)-body phantom in each CT scanner. Dose length product (DLP) for different anatomical regions was generated using CTDI values. The regional DRLs for thorax, abdomen and pelvis examinations were 557, 521 and 294 mGy cm, respectively. The mean effective dose was estimated using the DLP values and was found to be 8.04, 6.69 and 4.79 mSv for thorax, abdomen and pelvic CT examinations, respectively. The establishment of DRLs in this study is the first step towards optimization of CT doses in the Indian context.

  15. Measurements of gamma radiation levels and spectra in the San Francisco Bay Area

    NASA Astrophysics Data System (ADS)

    Lo, B. T.; Brozek, K. P.; Angell, C. T.; Norman, E. B.

    2011-10-01

    Much of the radiation received by an average person is emitted by naturally-occurring radioactive isotopes from the thorium, actinium, and uranium decay series, or potassium. In this study, we have measured gamma radiation levels at various locations in the San Francisco Bay Area and the UC Berkeley campus from spectra taken using an ORTEC NOMAD portable data acquisition system and a large-volume coaxial HPGe detector. We have identified a large number of gamma rays originating from natural sources. The most noticeable isotopes are 214Bi, 40K, and 208Tl. We have observed variations in counting rates by factors of two to five between different locations due to differences in local conditions - such as building, concrete, grass, and soil compositions. In addition, in a number of outdoor locations, we have observed 604-, 662-, and 795-keV gamma rays from 134,137Cs, which we attribute to fallout from the recent Fukushima reactor accident. The implications of these results will be discussed. This work was supported in part by a grant from the U. S. Dept. of Homeland Security.

  16. Diagnostic imaging and radiation exposure in inflammatory bowel disease.

    PubMed

    Zakeri, Nekisa; Pollok, Richard C G

    2016-02-21

    Diagnostic imaging plays a key role in the diagnosis and management of inflammatory bowel disease (IBD). However due to the relapsing nature of IBD, there is growing concern that IBD patients may be exposed to potentially harmful cumulative levels of ionising radiation in their lifetime, increasing malignant potential in a population already at risk. In this review we explore the proportion of IBD patients exposed to high cumulative radiation doses, the risk factors associated with higher radiation exposures, and we compare conventional diagnostic imaging with newer radiation-free imaging techniques used in the evaluation of patients with IBD. While computed tomography (CT) performs well as an imaging modality for IBD, the effective radiation dose is considerably higher than other abdominal imaging modalities. It is increasingly recognised that CT imaging remains responsible for the majority of diagnostic medical radiation to which IBD patients are exposed. Magnetic resonance imaging (MRI) and small intestine contrast enhanced ultrasonography (SICUS) have now emerged as suitable radiation-free alternatives to CT imaging, with comparable diagnostic accuracy. The routine use of MRI and SICUS for the clinical evaluation of patients with known or suspected small bowel Crohn's disease is to be encouraged wherever possible. More provision is needed for out-of-hours radiation-free imaging modalities to reduce the need for CT.

  17. Diagnostic imaging and radiation exposure in inflammatory bowel disease

    PubMed Central

    Zakeri, Nekisa; Pollok, Richard CG

    2016-01-01

    Diagnostic imaging plays a key role in the diagnosis and management of inflammatory bowel disease (IBD). However due to the relapsing nature of IBD, there is growing concern that IBD patients may be exposed to potentially harmful cumulative levels of ionising radiation in their lifetime, increasing malignant potential in a population already at risk. In this review we explore the proportion of IBD patients exposed to high cumulative radiation doses, the risk factors associated with higher radiation exposures, and we compare conventional diagnostic imaging with newer radiation-free imaging techniques used in the evaluation of patients with IBD. While computed tomography (CT) performs well as an imaging modality for IBD, the effective radiation dose is considerably higher than other abdominal imaging modalities. It is increasingly recognised that CT imaging remains responsible for the majority of diagnostic medical radiation to which IBD patients are exposed. Magnetic resonance imaging (MRI) and small intestine contrast enhanced ultrasonography (SICUS) have now emerged as suitable radiation-free alternatives to CT imaging, with comparable diagnostic accuracy. The routine use of MRI and SICUS for the clinical evaluation of patients with known or suspected small bowel Crohn’s disease is to be encouraged wherever possible. More provision is needed for out-of-hours radiation-free imaging modalities to reduce the need for CT. PMID:26900282

  18. The association betweeen cancers and low level radiation: An evaluation of the epidemiological evidence at the Hanford Nuclear Weapons Facility

    SciTech Connect

    Britton, J. |

    1993-05-01

    Cancer has traditionally been linked to exposure to high doses of radiation, but there is considerable controversy regarding the carcinogenicity of low doses of ionizing radiation in humans. Over the past 30 years there have been 14 studies conducted on employees at the Hanford nuclear weapons facility to investigate the relationship between exposure to low doses of radiation and mortality due to cancer (1-14). Interest in this issue was originally stimulated by the Atomic Energy Commission (AEC) which was trying to determine whether the linear extrapolation of health effects from high to low dose exposure was accurate. If the risk has been underestimated, then the maximum permissible occupational radiation exposure in the United States had been set too high. Because the health risk associated with low level radiation are unclear and controversial it seems appropriate to review the studies relating to Hanford at this time.

  19. Ionisation Mechanisms in AN Optically Pumped Mercury Vapour.

    NASA Astrophysics Data System (ADS)

    Counsell, G. F.

    Available from UMI in association with The British Library. Requires signed TDF. A plasma formed in a mercury vapour by optical pumping at visible and U.V. wavelengths from a high current mercury discharge, has been investigated with a view to gaining an understanding of the ionisation processes giving rise to the plasma. These were believed to generate both atomic and molecular ions. The results of this work have applications in the fields of fluorescent lighting and the mercury-nitrogen laser. The plasma was studied with a variety of diagnostic tools. Electron number densities and temperatures were determined using Langmuir probes operating in the orbital motion limited regime. Populations of the 6^3 P triplet states, believed to be the only significantly populated excited states in the plasma, were determined using absorption spectroscopy. Lastly, a quadrupole mass spectrometer, coupled to the plasma with an electrostatic ion transport system, was used to investigate the flux of atomic and molecular ions to a body at floating potential in the plasma. The Langmuir probe and absorption spectroscopy results were included into a model describing ion motions in the plasma, based around the ion fluid equations and including source terms for the generation of atomic and molecular ions, both by electron impact and by binary collisions of atoms in the 6^3P triplet states. Where possible, ionisation rats in the model were calculated using published cross-sections. However, for the heavy body collisional processes in particular, many of these are unknown. Consequently, an attempt was made to determine these cross-sections by generating results from the model that could be compared to experimental measurements of the atomic and molecular ion fluxes to the mass spectrometer. A number of computational experiments were carried out, varying the cross-sections until a good fit to the experimental measurements was achieved. Using this technique it was possible to estimate cross

  20. Observation of tree-level B decays with ss production from gluon radiation.

    PubMed

    Aubert, B; Bona, M; Boutigny, D; Karyotakis, Y; Lees, J P; Poireau, V; Prudent, X; Tisserand, V; Zghiche, A; Garra Tico, J; Grauges, E; Lopez, L; Palano, A; Eigen, G; Stugu, B; Sun, L; Abrams, G S; Battaglia, M; Brown, D N; Button-Shafer, J; Cahn, R N; Groysman, Y; Jacobsen, R G; Kadyk, J A; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Lopes Pegna, D; Lynch, G; Mir, L M; Orimoto, T J; Ronan, M T; Tackmann, K; Wenzel, W A; Del Amo Sanchez, P; Hawkes, C M; Watson, A T; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Schroeder, T; Steinke, M; Walker, D; Asgeirsson, D J; Cuhadar-Donszelmann, T; Fulsom, B G; Hearty, C; Mattison, T S; McKenna, J A; Khan, A; Saleem, M; Teodorescu, L; Blinov, V E; Bukin, A D; Druzhinin, V P; Golubev, V B; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Todyshev, K Yu; Bondioli, M; Curry, S; Eschrich, I; Kirkby, D; Lankford, A J; Lund, P; Mandelkern, M; Martin, E C; Stoker, D P; Abachi, S; Buchanan, C; Foulkes, S D; Gary, J W; Liu, F; Long, O; Shen, B C; Zhang, L; Paar, H P; Rahatlou, S; Sharma, V; Berryhill, J W; Campagnari, C; Cunha, A; Dahmes, B; Hong, T M; Kovalskyi, D; Richman, J D; Beck, T W; Eisner, A M; Flacco, C J; Heusch, C A; Kroseberg, J; Lockman, W S; Schalk, T; Schumm, B A; Seiden, A; Williams, D C; Wilson, M G; Winstrom, L O; Chen, E; Cheng, C H; Fang, F; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Andreassen, R; Mancinelli, G; Meadows, B T; Mishra, K; Sokoloff, M D; Blanc, F; Bloom, P C; Chen, S; Ford, W T; Hirschauer, J F; Kreisel, A; Nagel, M; Nauenberg, U; Olivas, A; Smith, J G; Ulmer, K A; Wagner, S R; Zhang, J; Gabareen, A M; Soffer, A; Toki, W H; Wilson, R J; Winklmeier, F; Zeng, Q; Altenburg, D D; Feltresi, E; Hauke, A; Jasper, H; Merkel, J; Petzold, A; Spaan, B; Wacker, K; Brandt, T; Klose, V; Kobel, M J; Lacker, H M; Mader, W F; Nogowski, R; Schubert, J; Schubert, K R; Schwierz, R; Sundermann, J E; Volk, A; Bernard, D; Bonneaud, G R; Latour, E; Lombardo, V; Thiebaux, Ch; Verderi, M; Clark, P J; Gradl, W; Muheim, F; Playfer, S; Robertson, A I; Xie, Y; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cecchi, A; Cibinetto, G; Franchini, P; Luppi, E; Negrini, M; Petrella, A; Piemontese, L; Prencipe, E; Santoro, V; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Finocchiaro, G; Pacetti, S; Patteri, P; Peruzzi, I M; Piccolo, M; Rama, M; Zallo, A; Buzzo, A; Contri, R; Lo Vetere, M; Macri, M M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Chaisanguanthum, K S; Morii, M; Wu, J; Dubitzky, R S; Marks, J; Schenk, S; Uwer, U; Bard, D J; Dauncey, P D; Flack, R L; Nash, J A; Nikolich, M B; Panduro Vazquez, W; Tibbetts, M; Behera, P K; Chai, X; Charles, M J; Mallik, U; Meyer, N T; Ziegler, V; Cochran, J; Crawley, H B; Dong, L; Eyges, V; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gritsan, A V; Guo, Z J; Lae, C K; Denig, A G; Fritsch, M; Schott, G; Arnaud, N; Béquilleux, J; Davier, M; Grosdidier, G; Höcker, A; Lepeltier, V; Le Diberder, F; Lutz, A M; Pruvot, S; Rodier, S; Roudeau, P; Schune, M H; Serrano, J; Sordini, V; Stocchi, A; Wang, W F; Wormser, G; Lange, D J; Wright, D M; Bingham, I; Chavez, C A; Forster, I J; Fry, J R; Gabathuler, E; Gamet, R; Hutchcroft, D E; Payne, D J; Schofield, K C; Touramanis, C; Bevan, A J; George, K A; Di Lodovico, F; Menges, W; Sacco, R; Cowan, G; Flaecher, H U; Hopkins, D A; Paramesvaran, S; Salvatore, F; Wren, A C; Brown, D N; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Chia, Y M; Edgar, C L; Lafferty, G D; West, T J; Yi, J I; Anderson, J; Chen, C; Jawahery, A; Roberts, D A; Simi, G; Tuggle, J M; Blaylock, G; Dallapiccola, C; Hertzbach, S S; Li, X; Moore, T B; Salvati, E; Saremi, S; Cowan, R; Dujmic, D; Fisher, P H; Koeneke, K; Sciolla, G; Sekula, S J; Spitznagel, M; Taylor, F; Yamamoto, R K; Zhao, M; Zheng, Y; McLachlin, S E; Patel, P M; Robertson, S H; Lazzaro, A; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Simard, M; Taras, P; Viaud, F B; Nicholson, H; De Nardo, G; Fabozzi, F; Lista, L; Monorchio, D; Sciacca, C; Baak, M A; Raven, G; Snoek, H L; Jessop, C P; Losecco, J M; Benelli, G; Corwin, L A; Honscheid, K; Kagan, H; Kass, R; Morris, J P; Rahimi, A M; Regensburger, J J; Wong, Q K; Blount, N L; Brau, J; Frey, R; Igonkina, O; Kolb, J A; Lu, M; Rahmat, R; Sinev, N B; Strom, D; Strube, J; Torrence, E; Gagliardi, N; Gaz, A; Margoni, M; Morandin, M; Pompili, A; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; Ben-Haim, E; Briand, H; Calderini, G; Chauveau, J; David, P; Del Buono, L; de la Vaissière, Ch; Hamon, O; Leruste, Ph; Malclès, J; Ocariz, J; Perez, A; Gladney, L; Biasini, M; Covarelli, R; Manoni, E; Angelini, C; Batignani, G; Bettarini, S; Carpinelli, M; Cenci, R; Cervelli, A; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Mazur, M A; Morganti, M; Neri, N; Paoloni, E; Rizzo, G; Walsh, J J; Haire, M; Biesiada, J; Elmer, P; Lau, Y P; Lu, C; Olsen, J; Smith, A J S; Telnov, A V; Baracchini, E; Bellini, F; Cavoto, G; D'Orazio, A; Del Re, D; Di Marco, E; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Jackson, P D; Li Gioi, L; Mazzoni, M A; Morganti, S; Piredda, G; Polci, F; Renga, F; Voena, C; Ebert, M; Hartmann, T; Schröder, H; Waldi, R; Adye, T; Castelli, G; Franek, B; Olaiya, E O; Ricciardi, S; Roethel, W; Wilson, F F; Aleksan, R; Emery, S; Escalier, M; Gaidot, A; Ganzhur, S F; Hamel de Monchenault, G; Kozanecki, W; Vasseur, G; Yèche, Ch; Zito, M; Chen, X R; Liu, H; Park, W; Purohit, M V; Wilson, J R; Allen, M T; Aston, D; Bartoldus, R; Bechtle, P; Berger, N; Claus, R; Coleman, J P; Convery, M R; Dingfelder, J C; Dorfan, J; Dubois-Felsmann, G P; Dunwoodie, W; Field, R C; Glanzman, T; Gowdy, S J; Graham, M T; Grenier, P; Hast, C; Hryn'ova, T; Innes, W R; Kaminski, J; Kelsey, M H; Kim, H; Kim, P; Kocian, M L; Leith, D W G S; Li, S; Luitz, S; Luth, V; Lynch, H L; Macfarlane, D B; Marsiske, H; Messner, R; Muller, D R; O'Grady, C P; Ofte, I; Perazzo, A; Perl, M; Pulliam, T; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Snyder, A; Stelzer, J; Su, D; Sullivan, M K; Suzuki, K; Swain, S K; Thompson, J M; Va'vra, J; van Bakel, N; Wagner, A P; Weaver, M; Wisniewski, W J; Wittgen, M; Wright, D H; Yarritu, A K; Yi, K; Young, C C; Burchat, P R; Edwards, A J; Majewski, S A; Petersen, B A; Wilden, L; Ahmed, S; Alam, M S; Bula, R; Ernst, J A; Jain, V; Pan, B; Saeed, M A; Wappler, F R; Zain, S B; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Ritchie, J L; Ruland, A M; Schilling, C J; Schwitters, R F; Izen, J M; Lou, X C; Ye, S; Bianchi, F; Gallo, F; Gamba, D; Pelliccioni, M; Bomben, M; Bosisio, L; Cartaro, C; Cossutti, F; Della Ricca, G; Lanceri, L; Vitale, L; Azzolini, V; Lopez-March, N; Martinez-Vidal, F; Milanes, D A; Oyanguren, A; Albert, J; Banerjee, Sw; Bhuyan, B; Hamano, K; Kowalewski, R; Nugent, I M; Roney, J M; Sobie, R J; Back, J J; Harrison, P F; Ilic, J; Latham, T E; Mohanty, G B; Pappagallo, M; Band, H R; Chen, X; Dasu, S; Flood, K T; Hollar, J J; Kutter, P E; Pan, Y; Pierini, M; Prepost, R; Wu, S L; Neal, H

    2008-05-02

    We report on our search for decays proceeding via a tree-level b-->c quark transition in which a gluon radiates into an ss[over ] pair. We present observations of the decays B;{-}-->D_{s};{+}K;{-}pi;{-} and B[over ];{0}-->D_{s};{+}K_{S};{0}pi;{-} and evidence for B;{-}-->D_{s};{+}K;{-}K;{-} and set upper limits on the branching fractions for B[over ];{0}-->D_{s};{+}K_{S};{0}pi;{-} and B;{-}-->D_{s};{+}K;{-}K;{-} using 383x10;{6} Upsilon(4S)-->BB[over ] events collected by the BABAR detector at SLAC. We present evidence that the invariant mass distributions of D_{s};{+}K;{-} pairs from B;{-}-->D_{s};{+}K;{-}pi;{-} decays are inconsistent with the phase-space model, suggesting the presence of charm resonances lying below the D_{s};{+}K;{-} threshold.

  1. Misuse of statistics in the interpretation of data on low-level radiation

    SciTech Connect

    Hamilton, L.D.

    1982-01-01

    Four misuses of statistics in the interpretation of data of low-level radiation are reviewed: (1) post-hoc analysis and aggregation of data leading to faulty conclusions in the reanalysis of genetic effects of the atomic bomb, and premature conclusions on the Portsmouth Naval Shipyard data; (2) inappropriate adjustment for age and ignoring differences between urban and rural areas leading to potentially spurious increase in incidence of cancer at Rocky Flats; (3) hazard of summary statistics based on ill-conditioned individual rates leading to spurious association between childhood leukemia and fallout in Utah; and (4) the danger of prematurely published preliminary work with inadequate consideration of epidemiological problems - censored data - leading to inappropriate conclusions, needless alarm at the Portsmouth Naval Shipyard, and diversion of scarce research funds.

  2. AFOMP POLICY STATEMENT No. 2: recommended clinical radiation oncology medical physicist staffing levels in AFOMP countries.

    PubMed

    Round, W H; Tay, Y K; Ng, K H; Cheung, K Y; Fukuda, S; Han, Y; Huang, Y X; Kim, H J; Krisanachinda, A; Liu, H L

    2010-03-01

    This document is the second of a series of policy statements being issued by the Asia-Oceania Federation of Organizations for Medical Physics (AFOMP). The document was developed by the AFOMP Professional Development Committee (PDC) and was released by the AFOMP Council in 2009. The main purpose of the document is to give guidance as to how many medical physicists are required to staff a radiation oncology department. Strict guidelines are difficult to define as work practices vary from country-to-country and from hospital-to-hospital. A calculation scheme is presented to aid in estimating medical physics staffing requirements that is primarily based on equipment levels and patient numbers but also with allowances for staff training, professional development and leave requirements.

  3. Radioprotective effect of sesamol on gamma-radiation induced DNA damage, lipid peroxidation and antioxidants levels in cultured human lymphocytes.

    PubMed

    Prasad, N Rajendra; Menon, Venugopal P; Vasudev, V; Pugalendi, K V

    2005-05-05

    Sesamol pretreated (1, 5 and 10 microg/ml) lymphocytes were exposed to different doses of gamma-radiation, i.e., 1, 2 and 4 Gray (Gy) and the cellular changes were estimated by using cytokinesis blocked micronucleus assay (MN), dicentric aberration (DC), thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Radiation significantly increased MN, DC frequencies, TBARS levels and decreased GSH and antioxidant enzyme levels in a dose dependent manner. The highest damage to lymphocytes was observed at 4 Gy irradiation. On the other hand, sesamol pretreatment significantly decreased MN, DC frequencies, TBARS levels and increased GSH levels and SOD, CAT and GPx activities in a concentration dependent manner. At 1 Gy irradiation all concentrations of sesamol (1, 5 and 10 microg/ml) significantly protects the lymphocytes from radiation damage. At 2 Gy irradiation 5 and 10 microg/ml of sesamol shows significant radioprotection. Since the highest damage was observed at 4 Gy irradiation both 1 and 5 microg/ml of sesamol pretreatment were not sufficient to protect the lymphocytes from radiation damage but 10 microg/ml of sesamol significantly (p<0.05) protects the lymphocytes from radiation effect. Thus, sesamol pretreatment gives significant protection to cultured human lymphocytes against gamma-radiation induced cellular damage. The possible mechanism involved in the radioprotective influence of sesamol is discussed.

  4. PAFOG—a new efficient forecast model of radiation fog and low-level stratiform clouds

    NASA Astrophysics Data System (ADS)

    Bott, Andreas; Trautmann, Thomas

    The new one-dimensional forecast model PAFOG for radiation fogs and low-level stratiform clouds will be presented. The aim of the model is to improve the local visibility forecast on airports and other traffic locations where fog and low-level stratus frequently occur. PAFOG has been developed on the basis of the microphysical fog model MIFOG of Bott et al. [J. Atmos. Sci. 47 (1990) 2153]. To obtain a numerically efficient model, the detailed spectral cloud microphysics of MIFOG has been replaced by the parameterization scheme of Chaumerliac et al. [J. Geophys. Res. 92 (1987) 3114]. Furthermore, according to Siebert et al. [Beitr. Phys. Atmos. 65 (1992a) 93], a model for low vegetation is included in PAFOG so that now fog evolution as influenced by different types of vegetation can also be accounted for. The performance of PAFOG has been tested by comparing the model results with routine observations of the German Weather Service. Nine different weather periods comprising a total of 45 days have been investigated. In 41 cases, PAFOG yields agreement with the observations in terms of occurrence or nonoccurrence of fog or stratiform clouds. During radiation fogs, the calculated and observed visibilities are quite similar. However, in the model simulations the formation of dense fogs tends to be somewhat delayed. From the case studies with stratiform clouds, it is seen that cloud evolution in time and space strongly depends on the value of the large-scale subsidence. Since this quantity is not available from measurements, it must be provided by means of a numerical weather forecast model.

  5. Radiative Heating of the ISCCP Upper Level Cloud Regimes and its Impact on the Large-scale Tropical Circulation

    SciTech Connect

    Li, Wei; Schumacher, Courtney; McFarlane, Sally A.

    2013-01-31

    Radiative heating profiles of the International Satellite Cloud Climatology Project (ISCCP) cloud regimes (or weather states) were estimated by matching ISCCP observations with radiative properties derived from cloud radar and lidar measurements from the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) sites at Manus, Papua New Guinea, and Darwin, Australia. Focus was placed on the ISCCP cloud regimes containing the majority of upper level clouds in the tropics, i.e., mesoscale convective systems (MCSs), deep cumulonimbus with cirrus, mixed shallow and deep convection, and thin cirrus. At upper levels, these regimes have average maximum cloud occurrences ranging from 30% to 55% near 12 km with variations depending on the location and cloud regime. The resulting radiative heating profiles have maxima of approximately 1 K/day near 12 km, with equal heating contributions from the longwave and shortwave components. Upper level minima occur near 15 km, with the MCS regime showing the strongest cooling of 0.2 K/day and the thin cirrus showing no cooling. The gradient of upper level heating ranges from 0.2 to 0.4 K/(day∙km), with the most convectively active regimes (i.e., MCSs and deep cumulonimbus with cirrus) having the largest gradient. When the above heating profiles were applied to the 25-year ISCCP data set, the tropics-wide average profile has a radiative heating maximum of 0.45Kday-1 near 250 hPa. Column-integrated radiative heating of upper level cloud accounts for about 20% of the latent heating estimated by the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR). The ISCCP radiative heating of tropical upper level cloud only slightly modifies the response of an idealized primitive equation model forced with the tropics-wide TRMM PR latent heating, which suggests that the impact of upper level cloud is more important to large-scale tropical circulation variations because of convective feedbacks rather than direct forcing by

  6. Radiative lifetime and energy of the low-energy isomeric level in 229Th

    NASA Astrophysics Data System (ADS)

    Tkalya, E. V.; Schneider, Christian; Jeet, Justin; Hudson, Eric R.

    2015-11-01

    We estimate the range of the radiative lifetime and energy of the anomalous, low-energy 3 /2+(7.8 ±0.5 eV) state in the 229Th nucleus. Our phenomenological calculations are based on the available experimental data for the intensities of M 1 and E 2 transitions between excited levels of the 229Th nucleus in the Kπ[N nZΛ ] =5 /2+[633 ] and 3 /2+[631 ] rotational bands. We also discuss the influence of certain branching coefficients, which affect the currently accepted measured energy of the isomeric state. From this work, we establish a favored region, 0.66 ×106seV3/ω3≤τ ≤2.2 ×106seV3/ω3 , where the transition lifetime τ as a function of transition energy ω should lie at roughly the 95% confidence level. Together with the result of Beck et al. [LLNL-PROC-415170 (2009)], we establish a favored area where transition lifetime and energy should lie at roughly the 90% confidence level. We also suggest new nuclear physics measurements, which would significantly reduce the ambiguity in the present data.

  7. Site-specific changes in zinc levels in the epididymis of rats exposed to ionizing radiation

    NASA Astrophysics Data System (ADS)

    Homma-Takeda, S.; Nishimura, Y.; Watanabe, Y.; Yukawa, M.

    2007-07-01

    The epididymis is an accessory sex organ that plays an important role in sperm maturation and storage. Trace elements, such as copper (Cu), manganese (Mn), zinc (Zn) and selenium (Se), have a pivotal role in spermatogenesis. We studied the effects of radiation on trace element levels in the epididymis in male Wistar rats using inductively coupled plasma-mass spectrometry (ICP-MS). We determined trace element concentration in segment-dissected specimens and used micro-PIXE analysis to determine Zn in epididymal sections in situ. Zn concentrations in the caput and cauda epididymis of control rats were 37.7 ± 6.5 μg/g wet weight and 18.7 ± 4.1 μg/g wet weight, respectively. At 6 h after irradiation at a single dose of 5Gy, the Zn level decreased by 33% in the caput epididymis, whereas the level did not change in the cauda segment. Similar results were obtained for Se, but not both Cu and Mn. PIXE spot analysis revealed that Zn in the lumen of the epididymal tubules decreased after irradiation.

  8. Recombination in liquid filled ionisation chambers with multiple charge carrier species: Theoretical and numerical results

    NASA Astrophysics Data System (ADS)

    Aguiar, P.; González-Castaño, D. M.; Gómez, F.; Pardo-Montero, J.

    2014-10-01

    Liquid-filled ionisation chambers (LICs) are used in radiotherapy for dosimetry and quality assurance. Volume recombination can be quite important in LICs for moderate dose rates, causing non-linearities in the dose rate response of these detectors, and needs to be corrected for. This effect is usually described with Greening and Boag models for continuous and pulsed radiation respectively. Such models assume that the charge is carried by two different species, positive and negative ions, each of those species with a given mobility. However, LICs operating in non-ultrapure mode can contain different types of electronegative impurities with different mobilities, thus increasing the number of different charge carriers. If this is the case, Greening and Boag models can be no longer valid and need to be reformulated. In this work we present a theoretical and numerical study of volume recombination in parallel-plate LICs with multiple charge carrier species, extending Boag and Greening models. Results from a recent publication that reported three different mobilities in an isooctane-filled LIC have been used to study the effect of extra carrier species on recombination. We have found that in pulsed beams the inclusion of extra mobilities does not affect volume recombination much, a behaviour that was expected because Boag formula for charge collection efficiency does not depend on the mobilities of the charge carriers if the Debye relationship between mobilities and recombination constant holds. This is not the case in continuous radiation, where the presence of extra charge carrier species significantly affects the amount of volume recombination.

  9. Ionisation Chambers and Secondary Emission Monitors at the PROSCAN Beam Lines

    NASA Astrophysics Data System (ADS)

    Dölling, Rudolf

    2006-11-01

    PROSCAN, the dedicated new medical facility at PSI using proton beams for the treatment of deep seated tumours and eye melanoma, is now in the commissioning phase. Air filled ionisation chambers in several configurations are used as current monitors, profile monitors, halo, position and loss monitors at the PROSCAN beam lines. Similar monitors based on secondary emission are used for profile and current measurements in the regime where saturation deteriorates the accuracy of the ionisation chambers.

  10. [Levels of radiation exposure and radiation risk in flights aboard the orbital complex "Mir" and the International space station].

    PubMed

    Shafirkin, A V; Kolomenskiĭ, A V; Petrov, V M

    2001-01-01

    The paper presents results of calculating mean daily values of absorbed and equivalent doses from galactic cosmic rays (GCR) and Earth's radiation belts (ERB) to crew members on orbital missions aboard Mir and the International space station during solar minimum and maximum. Calculated doses were corrected in accordance with the dosimetric and spectrometric data from Mir missions 18 through to 23 that took place in the period of solar minimum. Contribution of local and albedo neutrons to equivalent dose was also taken into account. Presented are calculated total radiation risk and tumor risk over life time for Mir and ISS crews following missions of varying duration, and predictions for reduction in life span in view of recent dosimetric data.

  11. Radiation dose due to radon and thoron progeny inhalation in high-level natural radiation areas of Kerala, India.

    PubMed

    Omori, Yasutaka; Tokonami, Shinji; Sahoo, Sarata Kumar; Ishikawa, Tetsuo; Sorimachi, Atsuyuki; Hosoda, Masahiro; Kudo, Hiromi; Pornnumpa, Chanis; Nair, Raghu Ram K; Jayalekshmi, Padmavaty Amma; Sebastian, Paul; Akiba, Suminori

    2017-03-20

    In order to evaluate internal exposure to radon and thoron, concentrations for radon, thoron, and thoron progeny were measured for 259 dwellings located in high background radiation areas (HBRAs, outdoor external dose: 3-5 mGy y(-1)) and low background radiation areas (control areas, outdoor external dose: 1 mGy y(-1)) in Karunagappally Taluk, Kerala, India. The measurements were conducted using passive-type radon-thoron detectors and thoron progeny detectors over two six-month measurement periods from June 2010 to June 2011. The results showed no major differences in radon and thoron progeny concentrations between the HBRAs and the control areas. The geometric mean of the annual effective dose due to radon and thoron was calculated as 0.10 and 0.44 mSv, respectively. The doses were small, but not negligible compared with the external dose in the two areas.

  12. Radiation response of alloy T91 at damage levels up to 1000 peak dpa

    SciTech Connect

    Gigax, J. G.; Chen, T.; Kim, Hyosim; Wang, J.; Price, L. M.; Aydogan, E.; Maloy, S. A.; Schreiber, D. K.; Toloczko, M. B.; Garner, F. A.; Shao, Lin

    2016-12-01

    Ferritic/martensitic alloys are required for advanced reactor components to survive 500e600 neutroninduced dpa. Ion-induced void swelling of ferritic/martensitic alloy T91 in the quenched and tempered condition has been studied using a defocused, non-rastered 3.5 MeV Fe-ion beam at 475 C to produce damage levels up to 1000 peak displacements per atom (dpa). The high peak damage level of 1000 dpa is required to reach 500e600 dpa level due to injected interstitial suppression of void nucleation in the peak dpa region, requiring data extraction closer to the surface at lower dpa levels. At a relatively low peak damage level of 250 dpa, voids began to develop, appearing first in the near-surface region. With increasing ion fluence, swelling was observed deeper in the specimen, but remained completely suppressed in the back half of the ion range, even at 1000 peak dpa. The local differences in dpa rate in the front half of the ion range induce an “internal temperature shift” that strongly influences the onset of swelling, with shorter transient regimes resulting from lower dpa rates, in agreement not only with observations in neutron irradiation studies but also in various ion irradiations. Swelling was accompanied by radiation-induced precipitation of Cu-rich and Si, Ni, Mn-rich phases were observed by atom probe tomography, indicating concurrent microchemical evolution was in progress. In comparison to other ferritic/martensitic alloys during ion irradiation, T91 exhibits good swelling resistance with a swelling incubation period of about 400 local dpa.

  13. Radiation response of alloy T91 at damage levels up to 1000 peak dpa

    NASA Astrophysics Data System (ADS)

    Gigax, J. G.; Chen, T.; Kim, Hyosim; Wang, J.; Price, L. M.; Aydogan, E.; Maloy, S. A.; Schreiber, D. K.; Toloczko, M. B.; Garner, F. A.; Shao, Lin

    2016-12-01

    Ferritic/martensitic alloys are required for advanced reactor components to survive 500-600 neutron-induced dpa. Ion-induced void swelling of ferritic/martensitic alloy T91 in the quenched and tempered condition has been studied using a defocused, non-rastered 3.5 MeV Fe-ion beam at 475 °C to produce damage levels up to 1000 peak displacements per atom (dpa). The high peak damage level of 1000 dpa is required to reach 500-600 dpa level due to injected interstitial suppression of void nucleation in the peak dpa region, requiring data extraction closer to the surface at lower dpa levels. At a relatively low peak damage level of 250 dpa, voids began to develop, appearing first in the near-surface region. With increasing ion fluence, swelling was observed deeper in the specimen, but remained completely suppressed in the back half of the ion range, even at 1000 peak dpa. The local differences in dpa rate in the front half of the ion range induce an "internal temperature shift" that strongly influences the onset of swelling, with shorter transient regimes resulting from lower dpa rates, in agreement not only with observations in neutron irradiation studies but also in various ion irradiations. Swelling was accompanied by radiation-induced precipitation of Cu-rich and Si, Ni, Mn-rich phases were observed by atom probe tomography, indicating concurrent microchemical evolution was in progress. In comparison to other ferritic/martensitic alloys during ion irradiation, T91 exhibits good swelling resistance with a swelling incubation period of about 400 local dpa.

  14. Detection of Low Level Microwave Radiation Induced Deoxyribonucleic Acid Damage Vis-à-vis Genotoxicity in Brain of Fischer Rats

    PubMed Central

    Deshmukh, Pravin Suryakantrao; Megha, Kanu; Banerjee, Basu Dev; Ahmed, Rafat Sultana; Chandna, Sudhir; Abegaonkar, Mahesh Pandurang; Tripathi, Ashok Kumar

    2013-01-01

    Background: Non-ionizing radiofrequency radiation has been increasingly used in industry, commerce, medicine and especially in mobile phone technology and has become a matter of serious concern in present time. Objective: The present study was designed to investigate the possible deoxyribonucleic acid (DNA) damaging effects of low-level microwave radiation in brain of Fischer rats. Materials and Methods: Experiments were performed on male Fischer rats exposed to microwave radiation for 30 days at three different frequencies: 900, 1800 and 2450 MHz. Animals were divided into 4 groups: Group I (Sham exposed): Animals not exposed to microwave radiation but kept under same conditions as that of other groups, Group II: Animals exposed to microwave radiation at frequency 900 MHz at specific absorption rate (SAR) 5.953 × 10−4 W/kg, Group III: Animals exposed to 1800 MHz at SAR 5.835 × 10−4 W/kg and Group IV: Animals exposed to 2450 MHz at SAR 6.672 × 10−4 W/kg. At the end of the exposure period animals were sacrificed immediately and DNA damage in brain tissue was assessed using alkaline comet assay. Results: In the present study, we demonstrated DNA damaging effects of low level microwave radiation in brain. Conclusion: We concluded that low SAR microwave radiation exposure at these frequencies may induce DNA strand breaks in brain tissue. PMID:23833433

  15. Radiation dosimetry.

    PubMed Central

    Cameron, J

    1991-01-01

    This article summarizes the basic facts about the measurement of ionizing radiation, usually referred to as radiation dosimetry. The article defines the common radiation quantities and units; gives typical levels of natural radiation and medical exposures; and describes the most important biological effects of radiation and the methods used to measure radiation. Finally, a proposal is made for a new radiation risk unit to make radiation risks more understandable to nonspecialists. PMID:2040250

  16. Potential interactions between different levels of cosmic radiation and their influence on the assessment of radiation risk during a manned deep space mission

    NASA Astrophysics Data System (ADS)

    Mortazavi, S.

    Despite the fact that galactic cosmic rays is believed to be isotropic throughout interstellar space, solar flares and coronal mass ejections can produce sudden and dramatic increase in flux of particles and expose the astronauts to transient high levels of ionizing radiation Furthermore, astronauts receive extra doses in the course of their extravehicular activities. It has been estimated that exposure to unpredictable extremely large solar particle events would kill the astronauts without massive shielding in interplanetary space. It is also generally believed that the biological effects of small doses of ionizing radiation may lie below the detection limits. However, potential interactions between a small dose and a subsequent high dose are still a black box that its output may be much different from the effect of a high dose alone. Potential interactions from low and high doses can either be a simple additivity, adaptive responses or synergistic effects. Significant adaptive response has been demonstrated in humans after exposure to high levels of natural radiation. Furthermore, non-linear behavior has been observed for cosmic radiation. Recent long-term follow-up studies as well as studies performed on twins show that in contrast to early reports, the type of interaction is determined by intrinsic factors such as genetic constitution of each individual. Despite that these responses for low- LET radiations (mainly photons and beta particles) are documented to some extent, there are no data on possible interactions of high-energy protons or high-LET heavy ions. The assessment of potential interactions between chronic low doses and acute high doses of high energy protons and heavy ions will be of importance in practical radiation protection of cosmonauts during a deep space mission.

  17. Analysis of nitroaromatic compounds in complex samples using solid-phase microextraction and isotope dilution quantification gas chromatography-electron-capture negative ionisation mass spectrometry.

    PubMed

    Jönsson, S; Gustavsson, L; van Bavel, B

    2007-09-14

    A solid-phase microextraction (SPME) method using gas chromatography-electron-capture negative ionisation mass spectrometry (GC-ECNI-MS) and isotope dilution quantification for the analysis of nitroaromatic compounds in complex, water based samples has been optimised. For ionisation, ECNI was the most sensitive and selective method. SPME was compared to solid-phase extraction (SPE) and found to be more sensitive for these small volume samples. LODs were in the range 0.02-38ngL(-1) for SPME and 6-184ngL(-1) for SPE, respectively. The SPME method was applied on samples in the ngL(-1) level from artificial reed beds treated with sludge containing residues from explosives and pharmaceuticals.

  18. Effectiveness of ionizing radiation in reducing furan and acrylamide levels in foods.

    PubMed

    Fan, Xuetong; Mastovska, Katerina

    2006-10-18

    Furan and acrylamide are two possible carcinogens commonly found in many thermally processed foods. The possibility of using ionizing radiation to reduce the levels of thermally induced furan and acrylamide in water and selected foods was investigated. Aqueous furan solutions, and foods (frankfurters, sausages, infant sweet potatoes) that contained furan were irradiated to various doses of gamma-rays. Water and oil spiked with acrylamide and potato chips (a known acrylamide-containing food) were also irradiated. In addition, possible irradiation-induced formation of acrylamide in glucose and asparagine solutions was analyzed. Results showed that irradiation at 1.0 kGy destroyed almost all furan in water. In frankfurters, sausages, and infant sweet potatoes, the rate of irradiation-induced destruction of furan was much lower than the rate in water, although significant reductions in furan levels were observed in all foods. Irradiation at 2.5-3.5 kGy, doses that can inactivate 5-log of most common pathogens, reduced furan levels in the food samples by 25-40%. Similarly to furan, acrylamide in water was also sensitive to irradiation. After 1.5 kGy of irradiation, most of the acrylamide was degraded. Irradiation, however, had a very limited effect on acrylamide levels in oil and in potato chips, even at a dose of 10 kGy. No detectable acrylamide was formed in the mixture of asparagine and glucose upon irradiation. These results suggest that a low dose of irradiation easily destroys furan and acrylamide in water. In real foods, however, the reduction of furan was less effective than in water, whereas the reduction in acrylamide was minimal.

  19. Assessing the Space-Radiation Hazard in Ground-Level Enhanced (GLE) Solar Particle Events (Invited)

    NASA Astrophysics Data System (ADS)

    Tylka, A. J.; Dietrich, W. F.; Atwell, W. A.

    2010-12-01

    The most severe transient radiation hazards for human spaceflight in the historical record are solar particle events associated with so-called Ground-Level Enhancements (GLEs), in which processes at the Sun can accelerate protons to GeV energies in minutes. We report on recent efforts to improve the reliability of assessments of these radiation hazards. These efforts are based on a new analysis of the entire historical data base of GLEs from 1956-2006, using the complete ensemble of measurements from riometers, satellites, and neutron-monitors, from ˜10 MeV to ˜10 GeV. Of particular importance is the functional form of the proton spectrum. We have found that the event-integrated integral proton spectrum can generally be well represented by the so-called Band function (Band et al., ApJ 413, 281-292, 1993; a double power law with a smooth rollover) in rigidity. The residuals of these fits with respect to the data typically range from <10% for satellite measurements to <30% for neutron monitor measurements. We present a new catalogue of Band fit parameters for 58 out of the 66 GLEs that have been observed since 1956. We also examine how the dose-depth profiles calculated from these Band fits differ from earlier calculations, based on assumed functional forms derived from more limited datasets. For some of the larger events, we also show hour-by-hour analysis of the accumulated dose. Supported by ONR, NASA/SRAG (IPR NNJ09HC54I), and NASA LWS/TRT (DPR NNH09AL11I).

  20. Association between sperm DNA integrity and seminal plasma antioxidant levels in health workers occupationally exposed to ionizing radiation

    SciTech Connect

    Kumar, Dayanidhi; Salian, Sujith Raj; Kalthur, Guruprasad; Uppangala, Shubhashree; Kumari, Sandhya; Challapalli, Srinivas; Chandraguthi, Shrinidhi Gururajarao; Jain, Navya; Krishnamurthy, Hanumanthappa; Kumar, Pratap; Adiga, Satish Kumar

    2014-07-15

    There is a paucity of data regarding the association between occupational radiation exposure and risk to human fertility. Recently, we provided the first evidence on altered sperm functional characteristics, DNA damage and hypermethylation in radiation health workers. However, there is no report elucidating the association between seminal plasma antioxidants and sperm chromatin integrity in occupationally exposed subjects. Here, we assessed the seminal plasma antioxidants and lipid peroxidation level in 83 men who were occupationally exposed to ionizing radiation and then correlated with the sperm chromatin integrity. Flow cytometry based sperm chromatin integrity assay revealed a significant decline in αt value in the exposed group in comparison to the non-exposed group (P<0.0001). Similarly, both total and reduced glutathione levels and total antioxidant capacity in the seminal plasma were significantly higher in exposed group than the non-exposed group (P<0.01, 0.001 and 0.0001, respectively). However, superoxide dismutase level and malondialdehyde level, which is an indicator of lipid peroxidation in the seminal plasma, did not differ significantly between two groups. The total antioxidant capacity (TAC) and GSH level exhibited a positive correlation with sperm DNA integrity in exposed subjects. To conclude, this study distinctly shows that altered sperm chromatin integrity in radiation health workers is associated with increase in seminal plasma antioxidant level. Further, the increased seminal plasma GSH and TAC could be an adaptive measure to tackle the oxidative stress to protect genetic and functional sperm deformities in radiation health workers. - Highlights: • Seminal plasma antioxidants were measured in men occupationally exposed to radiation. • Sperm chromatin integrity was significantly affected in the exposed group. • Glutathione and total antioxidant capacity was significantly higher in exposed group. • Sperm DNA damage in exposed subjects

  1. Level crossing analysis of cosmic microwave background radiation: a method for detecting cosmic strings

    SciTech Connect

    Movahed, M. Sadegh; Khosravi, Shahram E-mail: khosravi@ipm.ir

    2011-03-01

    In this paper we study the footprint of cosmic string as the topological defects in the very early universe on the cosmic microwave background radiation. We develop the method of level crossing analysis in the context of the well-known Kaiser-Stebbins phenomenon for exploring the signature of cosmic strings. We simulate a Gaussian map by using the best fit parameter given by WMAP-7 and then superimpose cosmic strings effects on it as an incoherent and active fluctuations. In order to investigate the capability of our method to detect the cosmic strings for the various values of tension, Gμ, a simulated pure Gaussian map is compared with that of including cosmic strings. Based on the level crossing analysis, the superimposed cosmic string with Gμ∼>4 × 10{sup −9} in the simulated map without instrumental noise and the resolution R = 1' could be detected. In the presence of anticipated instrumental noise the lower bound increases just up to Gμ∼>5.8 × 10{sup −9}.

  2. Survey of studies of occupational populations exposed to low-level radiation

    SciTech Connect

    Marks, S.

    1980-04-01

    Studies of occupational populations exposed to large doses of radiation, principally from the ingestion of radium by dial painters and inhalation of radon and its daughters by miners, have provided important information on the health effects of those radioisotopes. Studies of medical radiologists, military personnel exposed to nuclear tests, and factory workers exposed to thorium are in progress. Employees of DOE-contractor facilities and of naval shipyards are also under study. Personnel dosimetry data are generally available for the latter category of occupational populations. Reasons for conducting the studies include interest in exploring the verification at low exposure levels of results of studies of heavily exposed populations and the responsibility of the employer to maintain adequate surveillance of the health of his workers by conducting appropriate epidemiologic studies. The low level of exposure of workers in facilities where adequate personnel dosimetry records are available make it unlikely that the results of such studies can be used to provide health risk estimates in the near future.

  3. Effect of gamma radiation on the ripening and levels of bioactive amines in bananas cv. Prata

    NASA Astrophysics Data System (ADS)

    Gloria, Maria Beatriz A.; Adão, Regina C.

    2013-06-01

    Green Prata bananas at the full three-quarter stage were exposed to gamma radiation at doses of 0.0 (control), 1.0, 1.5 and 2.0 kGy and stored at 16±1 °C and 85% relative humidity. Samples were collected periodically and analyzed for peel color, pulp-to-peel ratio and levels of starch, soluble sugars and bioactive amines. Degradation of starch and formation of fructose and glucose followed first- and zero-order kinetics, respectively. Higher irradiation doses caused increased inhibitory effect on starch degradation and glucose formation. However, doses of 1.5 and 2.0 kGy caused browning of the peel, making the fruit unacceptable. Irradiation at 1.0 kGy was the most promising dose: it did not affect peel color, the pulp-to-peel ratio or the levels of the amines spermidine, serotonin and putrescine. However, it slowed down starch degradation and the formation and accumulation of fructose and glucose, delaying the ripening of the fruit for 7 days.

  4. BOREAS RSS-14 Level-2 GOES-7 Shortwave and Longwave Radiation Images

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Nickeson, Jaime (Editor); Gu, Jiujing; Smith, Eric A.

    2000-01-01

    The BOREAS RSS-14 team collected and processed several GOES-7 and GOES-8 image data sets that covered the BOREAS study region. This data set contains images of shortwave and longwave radiation at the surface and top of the atmosphere derived from collected GOES-7 data. The data cover the time period of 05-Feb-1994 to 20-Sep-1994. The images missing from the temporal series were zero-filled to create a consistent sequence of files. The data are stored in binary image format files. Due to the large size of the images, the level-1a GOES-7 data are not contained on the BOREAS CD-ROM set. An inventory listing file is supplied on the CD-ROM to inform users of what data were collected. The level-1a GOES-7 image data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). See sections 15 and 16 for more information. The data files are available on a CD-ROM (see document number 20010000884).

  5. Theoretical oscillator strengths, transition probabilities, and radiative lifetimes of levels in Pb V

    SciTech Connect

    Colón, C.; Alonso-Medina, A.; Porcher, P.

    2014-01-15

    Theoretical values of oscillator strengths and transition probabilities for 306 spectral lines arising from the 5d{sup 9}ns(n=7,8,9),5d{sup 9}np(n=6,7),5d{sup 9}6d, and 5d{sup 9} 5f configurations, and radiative lifetimes of 9 levels, of Pb V have been obtained. These values were obtained in intermediate coupling (IC) and using ab initio relativistic Hartree–Fock calculations including core-polarization effects. We use for the IC calculations the standard method of least squares fitting of experimental energy levels by means of computer codes from Cowan. We included in these calculations the 5d{sup 8}6s6p and 5d{sup 8}6s{sup 2} configurations. These calculations have facilitated the identification of the 214.25, 216.79, and 227.66 nm spectral lines of Pb V. In the absence of experimental results of oscillator strengths and transition probabilities, we could not make a direct comparison with our results. However, the Stark broadening parameters calculated from these values are in excellent agreement with experimental widening found in the literature. -- Highlights: •Theoretical values of transition probabilities of Pb V have been obtained. •We use for the IC calculations the standard method of least square. •The parameters calculated from these values are in agreement with the experimental values.

  6. Haemopoietic cell renewal in radiation fields

    NASA Astrophysics Data System (ADS)

    Fliedner, T. M.; Nothdurft, W.; Tibken, B.; Hofer, E.; Weiss, M.; Kindler, H.

    1994-10-01

    Space flight activities are inevitably associated with a chronic exposure of astronauts to a complex mixture of ionising radiation. Although no acute radiation consequences are to be expected as a rule, the possibility of Solar Particle Events (SPE) associated with relatively high doses of radiation (1 or more Gray) cannot be excluded. It is the responsibility of physicians in charge of the health of astronauts to evaluate before, during and after space flight activities the functional status of haemopoietic cell renewal. Chronic low level exposure of dogs indicate that daily gamma-exposure doses below about 2 cGy are tolerated for several years as far as blood cell concentrations are concerned. However, the stem cell pool may be severely affected. The maintenance of sufficient blood cell counts is possible only through increased cell production to compensate for the radiation inflicted excess cell loss. This behaviour of haemopoietic cell renewal during chronic low level exposure can be simulated by bioengineering models of granulocytopoiesis. It is possible to define a ``turbulence region'' for cell loss rates, below which an prolonged adaptation to increased radiation fields can be expected to be tolerated. On the basis of these experimental results, it is recommended to develop new biological indicators to monitor haemopoietic cell renewal at the level of the stem cell pool using blood stem cells in addition to the determination of cytokine concentrations in the serum (and other novel approaches). To prepare for unexpected haemopoietic effects during prolonged space missions, research should be increased to modify the radiation sensitivity of haemopoietic stem cells (for instance by the application of certain regulatory molecules). In addition, a ``blood stem cell bank'' might be established for the autologous storage of stem cells and for use in space activities keeping them in a radiation protected container.

  7. Dr. Robert Clark studies levels of radiation Skylab 2 crew was exposed to

    NASA Technical Reports Server (NTRS)

    1973-01-01

    In the Radiation Counting Laboratory sixty feet underground at JSC, Dr. Robert S. Clark prepares to load pieces of iridium foil - sandwiched between plastic sheets - into the laboratory's radiation detector. The iridium foil strips were worn by the crew of the second Skylab flight in personal radiation dosimeters throughout their 59.5 days in space. Inside the radiation detector assembly surrounded by 28 tons of lead shielding, the sample will be tested to determine the total neutron dose to which the astronauts were exposed during their long stay aboard the space station.

  8. Excitation and Ionisation dynamics in high-frequency plasmas

    NASA Astrophysics Data System (ADS)

    O'Connell, D.

    2008-07-01

    Non-thermal low temperature plasmas are widely used for technological applications. Increased demands on plasma technology have resulted in the development of various discharge concepts based on different power coupling mechanisms. Despite this, power dissipation mechanisms in these discharges are not yet fully understood. Of particular interest are low pressure radio-frequency (rf) discharges. The limited understanding of these discharges is predominantly due to the complexity of the underlying mechanisms and difficult diagnostic access to important parameters. Optical measurements are a powerful diagnostic tool offering high spatial and temporal resolution. Optical emission spectroscopy (OES) provides non-intrusive access, to the physics of the plasma, with comparatively simple experimental requirements. Improved advances in technology and modern diagnostics now allow deeper insight into fundamental mechanisms. In low pressure rf discharges insight into the electron dynamics within the rf cycle can yield vital information. This requires high temporal resolution on a nano-second time scale. The optical emission from rf discharges exhibits temporal variations within the rf cycle. These variations are particularly strong, in for example capacitively coupled plasmas (CCPs), but also easily observable in inductively coupled plasmas (ICPs), and can be exploited for insight into power dissipation. Interesting kinetic and non-linear coupling effects are revealed in capacitive systems. The electron dynamics exhibits a complex spatio-temporal structure. Excitation and ionisation, and, therefore, plasma sustainment is dominated through directed energetic electrons created through the dynamics of the plasma boundary sheath. In the relatively simple case of an asymmetric capacitively coupled rf plasma the complexity of the power dissipation is exposed and various mode transitions can be clearly observed and investigated. At higher pressure secondary electrons dominate the

  9. Comparison of ionisation chamber and semiconductor detector devices for measurement of the dose-width product for panoramic dental units.

    PubMed

    Mitchell, S A; Martin, C J

    2013-06-01

    Doses for panoramic dental radiography are assessed in terms of the dose-width product (DWP) or dose-area product, which gives a measure of the radiation through a whole exposure. The DWP can be measured using a pencil ionisation chamber (IC) similar to that used for computed tomography dose assessment. However, ICs are sensitive to radiation incident from all directions and so backscatter from the image receptor may increase the recorded dose. This study compares measurements performed using four options: a pencil IC mounted straight on the image receptor, the IC mounted with a steel plate to the rear to standardise scatter conditions, the IC mounted with a steel plate and lead collimators in front to minimise the effect of extra-focal radiation, and a Quart Dido employing a one square centimetre semiconductor detector (SD) designed for panoramic measurements. The results indicate that modification of the current method by incorporating a steel plate reduced the measurement dose by 7% on average, but the reduction was greater for units with semiconductor imaging plates. The measurements with the SD agree more closely with the IC with the steel plate to the rear. An IC with a backing plate to standardise scatter or a suitable SD is recommended for measurement on panoramic dental units.

  10. Ionizing radiation effects on sex steroid hormone levels in serum and milt of freshwater fish Oreochromis mossambicus.

    PubMed

    Saiyad Musthafa, M; Jawahar Ali, A; Mohamed Ahadhu Shareef, T H; Vijayakumar, S; Iyanar, K; Thangaraj, K

    2014-03-01

    Effects of gamma rays on the sex steroid hormone levels [testosterone (T), 11-ketotestosterone (11-KT) and 17β-estradiol (E2)] were studied in the freshwater fish Oreochromis mossambicus. Gamma radiation induced effects on hormone levels reported here for the first time in the fish. Since radionuclides released accidentally or during a nuclear disaster can contaminate inland water bodies, biomonitoring methods are required for assessing the impacts of certain dose levels of radiation that may ultimately result in ionizing radiation exposure to both humans and non-human biota. Three groups of (n=15 in each group) fishes were irradiated with a single dose of (60)Co 10Gy, 15Gy and 20Gy with a duration of .33, .50 and .66min. Significant decrease of the hormone levels was seen at higher doses of 15Gy and 20Gy. The sex steroid hormone levels in the fishes are vital for sperm production, development, differential functions related to the physiology and reproductive behavior. This study serves as biomonitoring tool to assess the ionizing radiation effects on reproductive behavior of aquatic biota.

  11. State background-radiation levels: results of measurements taken during 1975-1979

    SciTech Connect

    Myrick, T.E.; Berven, B.A.; Haywood, F.F.

    1981-11-01

    Background radiation levels across the United States have been measured by the Off-Site Pollutant Measurements Group of the Health and Safety Research Division at Oak Ridge National Laboratory (ORNL). These measurements have been conducted as part of the ORNL program of radiological surveillance at inactive uranium mills and sites formerly utilized during Manhattan Engineer District and early Atomic Energy Commission projects. The measurements included determination of /sup 226/Ra, /sup 232/Th, and /sup 238/U concentrations in surface soil samples and measurement of external gamma-ray exposure rates at 1 m above the ground surface at the location of soil sampling. This information is being utilized for comparative purposes to determine the extent of contamination present at the survey sites and surrounding off-site areas. The sampling program to date has provided background information at 356 locations in 33 states. External gamma-ray exposure rates were found to range from less than 1 to 34 ..mu..R/h, with an US average of 8.5 ..mu..R/h. The nationwide average concentrations of /sup 226/Ra, /sup 232/Th, and /sup 238/U in surface soil were determined to be 1.1, 0.98, and 1.0 pCi/g, respectively.

  12. Regular and Chaotic Quantum Dynamics of Two-Level Atoms in a Selfconsistent Radiation Field

    NASA Technical Reports Server (NTRS)

    Konkov, L. E.; Prants, S. V.

    1996-01-01

    Dynamics of two-level atoms interacting with their own radiation field in a single-mode high-quality resonator is considered. The dynamical system consists of two second-order differential equations, one for the atomic SU(2) dynamical-group parameter and another for the field strength. With the help of the maximal Lyapunov exponent for this set, we numerically investigate transitions from regularity to deterministic quantum chaos in such a simple model. Increasing the collective coupling constant b is identical with 8(pi)N(sub 0)(d(exp 2))/hw, we observed for initially unexcited atoms a usual sharp transition to chaos at b(sub c) approx. equal to 1. If we take the dimensionless individual Rabi frequency a = Omega/2w as a control parameter, then a sequence of order-to-chaos transitions has been observed starting with the critical value a(sub c) approx. equal to 0.25 at the same initial conditions.

  13. Use of gamma radiation on control of Clostridium botulinum in mortadella formulated with different nitrite levels

    NASA Astrophysics Data System (ADS)

    Dutra, Monalisa Pereira; Aleixo, Glécia de Cássia; Ramos, Alcinéia de Lemos Souza; Silva, Maurício Henriques Louzada; Pereira, Marcio Tadeu; Piccoli, Roberta Hilsdorf; Ramos, Eduardo Mendes

    2016-02-01

    This study investigated the effects of applying different doses of gamma radiation (0, 10 and 20 kGy) on Clostridium botulinum spores (107 spores/g) inoculated into mortadellas with different nitrite contents (0, 150 and 300 ppm). We also evaluated the order of application of heat (cooking) and irradiation processing. The products were evaluated for survival of C. botulinum, pH, water activity (Aw), redox potential (Eh) and residual nitrite content. In the non-irradiated raw batters, almost all spores could be recovered when no nitrite was added and only half was recovered with the addition of 150 ppm of nitrite. The use of 150 ppm of nitrite was able to inhibit the germination or growth of C. botulinum in non-irradiated cooked mortadellas after 48 h of processing. However, after 30 days of chilling storage (4 °C), it was possible to recover 105 UFC/g of this microorganism. The gamma irradiation (>10 kGy) had a positive effect on the inactivation of C. botulinum in mortadellas, independent of the sodium nitrite level used and the cooking/irradiation processing order.

  14. Development of a new ionisation chamber, for HP(10) measurement, using Monte-Carlo simulation and experimental methods.

    PubMed

    Silva, H; Cardoso, J; Oliveira, C

    2011-03-01

    An ionisation chamber that directly measures the quantity personal dose equivalent, H(p)(10), is used as a secondary standard in some metrology laboratories. An ionisation chamber of this type was first developed by Ankerhold. Using the Monte-Carlo simulation, the dose in the sensitive volume as a function of the IC dimensions and the effects of the several components of the ionising chamber have been investigated. Based on these results, a new ionising chamber, lighter than the previous ones, is constructed and experimentally tested.

  15. Soybean fruit development and set at the node level under combined photoperiod and radiation conditions.

    PubMed

    Nico, Magalí; Mantese, Anita I; Miralles, Daniel J; Kantolic, Adriana G

    2016-01-01

    In soybean, long days during post-flowering increase seed number. This positive photoperiodic effect on seed number has been previously associated with increments in the amount of radiation accumulated during the crop cycle because long days extend the duration of the crop cycle. However, evidence of intra-nodal processes independent of the availability of assimilates suggests that photoperiodic effects at the node level might also contribute to pod set. This work aims to identify the main mechanisms responsible for the increase in pod number per node in response to long days; including the dynamics of flowering, pod development, growth and set at the node level. Long days increased pods per node on the main stems, by increasing pods on lateral racemes (usually dominated positions) at some main stem nodes. Long days lengthened the flowering period and thereby increased the number of opened flowers on lateral racemes. The flowering period was prolonged under long days because effective seed filling was delayed on primary racemes (dominant positions). Long days also delayed the development of flowers into pods with filling seeds, delaying the initiation of pod elongation without modifying pod elongation rate. The embryo development matched the external pod length irrespective of the pod's chronological age. These results suggest that long days during post-flowering enhance pod number per node through a relief of the competition between pods of different hierarchy within the node. The photoperiodic effect on the development of dominant pods, delaying their elongation and therefore postponing their active growth, extends flowering and allows pod set at positions that are usually dominated.

  16. Tritium: a model for low level long-term ionizing radiation exposure

    SciTech Connect

    Carsten, A.L.

    1984-01-01

    The somatic, cytogenetic and genetic effects of single and chronic tritiated water (HTO) ingestion in mice was investigated. This study serves not only as an evaluation of tritium toxicity (TRITOX) but due to its design involving long-term low concentration ingestion of HTO may serve as a model for low level long-term ionizing radiation exposure in general. Long-term studies involved animals maintained on HTO at concentrations of 0.3 ..mu..Ci/ml, 1.0 ..mu..Ci/ml, 3.0 ..mu..Ci/ml or depth dose equivalent chronic external exposures to /sup 137/Cs gamma rays. Maintenance on 3.0 ..mu..Ci/ml resulted in no effect on growth, life-time shortening or bone marrow cellularity, but did result in a reduction of bone marrow stem cells, an increase in DLM's in second generation animals maintained on this regimen and cytogenetic effects as indicated by increased sister chromatid exchanges (SCE's) in bone marrow cells, increased chromosome aberrations in the regenerating liver and an increase in micronuclei in red blood cells. Biochemical and microdosimetry studies showed that animals placed on the HTO regimen reached tritium equilibrium in the body water in approximately 17 to 21 days with a more gradual increase in bound tritium. When animals maintained for 180 days on 3.0 ..mu..Ci/ml HTO were placed on a tap water regimen, the tritium level in tissue dropped from the equilibrium value of 2.02 ..mu..Ci/ml before withdrawal to 0.001 ..mu..Ci/ml at 28 days. 18 references.

  17. Fifth Warren K. Sinclair Keynote Address: Issues in quantifying the effects of low-level radiation.

    PubMed

    Goodhead, Dudley T

    2009-11-01

    Health risks from exposure to high doses of ionizing radiation are well characterized from epidemiological studies. Uncertainty and controversy remain for extension of these risks to the low doses and low dose rates of particular relevance in the workplace, in medical diagnostics and screening, and from background radiations. In order to make such extrapolations, a number of concepts have been developed for radiation protection, partly on the basis of assumed processes in the mechanisms of radiation carcinogenesis. Included amongst these are the assumptions of a linear no-threshold dose response and simple scaling factors for dose rate and radiation quality. With a progressive reduction in recommended dose limits over the past half century, these approaches have had considerable success in protecting humans. But do they go far enough or, conversely, are they overprotective? Four selected underlying aspects are considered. It is concluded that (1) even the lowest dose of radiation has the capability to cause complex DNA damage that can lead to a variety of permanent cellular changes; (2) the unique clustered characteristics of radiation damage, even at very low doses, enable it to stand out above the much larger quantity of endogenous DNA damage; (3) although a chromosome aberration may represent the rate-limiting initiating event for carcinogenesis, as is often assumed, direct evidence is still lacking; and (4) the extensive influence that dicentric aberrations have had on guiding extrapolations for radiation protection may be substantially misleading. Finally, some comments are offered on aspects that lie outside the current paradigm.

  18. Cancer Mortality Among People Living in Areas With Various Levels of Natural Background Radiation.

    PubMed

    Dobrzyński, Ludwik; Fornalski, Krzysztof W; Feinendegen, Ludwig E

    2015-01-01

    There are many places on the earth, where natural background radiation exposures are elevated significantly above about 2.5 mSv/year. The studies of health effects on populations living in such places are crucially important for understanding the impact of low doses of ionizing radiation. This article critically reviews some recent representative literature that addresses the likelihood of radiation-induced cancer and early childhood death in regions with high natural background radiation. The comparative and Bayesian analysis of the published data shows that the linear no-threshold hypothesis does not likely explain the results of these recent studies, whereas they favor the model of threshold or hormesis. Neither cancers nor early childhood deaths positively correlate with dose rates in regions with elevated natural background radiation.

  19. Health Effects of Low Level Radiation: When Will We Acknowledge the Reality?

    PubMed Central

    Cuttler, J. M.

    2007-01-01

    The 1986 April 26th Chernobyl event was the worst nuclear power accident—it killed 31 people. Its significance was exaggerated immensely because of the pervasive fear of ionizing radiation that has been indoctrinated in all of humanity. In reality, our environment includes radiation from natural sources, varying widely in intensity, to which all living things have adapted. The effect of radiation on organisms is primarily on their damage control biosystem, which prevents, repairs and removes cell damage. Low doses stimulate this system, while high doses inhibit it. So low doses decrease the incidences of cancer and congenital malformations; high doses have the opposite effect. Efforts by radiation protection organizations to lower exposures to (human-made) radiation to as low as reasonably achievable (ALARA) provide no benefit. They only create inappropriate fear—barriers to very important applications of nuclear technology in energy production and medicine. PMID:18648566

  20. Cancer Mortality Among People Living in Areas With Various Levels of Natural Background Radiation

    PubMed Central

    Fornalski, Krzysztof W.; Feinendegen, Ludwig E.

    2015-01-01

    There are many places on the earth, where natural background radiation exposures are elevated significantly above about 2.5 mSv/year. The studies of health effects on populations living in such places are crucially important for understanding the impact of low doses of ionizing radiation. This article critically reviews some recent representative literature that addresses the likelihood of radiation-induced cancer and early childhood death in regions with high natural background radiation. The comparative and Bayesian analysis of the published data shows that the linear no-threshold hypothesis does not likely explain the results of these recent studies, whereas they favor the model of threshold or hormesis. Neither cancers nor early childhood deaths positively correlate with dose rates in regions with elevated natural background radiation. PMID:26674931

  1. Fundamentals of Radiation Dosimetry

    SciTech Connect

    Bos, Adrie J. J.

    2011-05-05

    The basic concepts of radiation dosimetry are reviewed on basis of ICRU reports and text books. The radiation field is described with, among others, the particle fluence. Cross sections for indirectly ionizing radiation are defined and indicated is how they are related to the mass energy transfer and mass energy absorption coefficients. Definitions of total and restricted mass stopping powers of directly ionizing radiation are given. The dosimetric quantities, kerma, absorbed dose and exposure together with the relations between them are discussed in depth. Finally it is indicated how the absorbed dose can be measured with a calorimeter by measuring the temperature increase and with an ionisation chamber measuring the charge produced by the ionizing radiation and making use of the Bragg-Gray relation.

  2. Fundamentals of Radiation Dosimetry

    NASA Astrophysics Data System (ADS)

    Bos, Adrie J. J.

    2011-05-01

    The basic concepts of radiation dosimetry are reviewed on basis of ICRU reports and text books. The radiation field is described with, among others, the particle fluence. Cross sections for indirectly ionizing radiation are defined and indicated is how they are related to the mass energy transfer and mass energy absorption coefficients. Definitions of total and restricted mass stopping powers of directly ionizing radiation are given. The dosimetric quantities, kerma, absorbed dose and exposure together with the relations between them are discussed in depth. Finally it is indicated how the absorbed dose can be measured with a calorimeter by measuring the temperature increase and with an ionisation chamber measuring the charge produced by the ionizing radiation and making use of the Bragg-Gray relation.

  3. Level Densities and Radiative Strength Functions in 56FE and 57FE

    SciTech Connect

    Tavukcu, Emel

    2002-12-10

    Understanding nuclear level densities and radiative strength functions is important for pure and applied nuclear physics. Recently, the Oslo Cyclotron Group has developed an experimental method to extract level densities and radiative strength functions simultaneously from the primary γ rays after a light-ion reaction. A primary γ-ray spectrum represents the γ-decay probability distribution. The Oslo method is based on the Axel-Brink hypothesis, according to which the primary γ-ray spectrum is proportional to the product of the level density at the final energy and the radiative strength function. The level density and the radiative strength function are fit to the experimental primary γ-ray spectra, and then normalized to known data. The method works well for heavy nuclei. The present measurements extend the Oslo method to the lighter mass nuclei 56Fe and 57Fe. The experimental level densities in 56Fe and 57Fe reveal step structure. This step structure is a signature for nucleon pair breaking. The predicted pairing gap parameter is in good agreement with the step corresponding to the first pair breaking. Thermodynamic quantities for 56Fe and 57Fe are derived within the microcanonical and canonical ensembles using the experimental level densities. Energy-temperature relations are considered using caloric curves and probability density functions. The differences between the thermodynamics of small and large systems are emphasized. The experimental heat capacities are compared with the recent theoretical calculations obtained in the Shell Model Monte Carlo method. Radiative strength functions in 56Fe and 57Fe have surprisingly high values at low γ-ray energies. This behavior has not been observed for heavy nuclei, but has been observed in other light- and medium-mass nuclei. The origin of this low γ-ray energy effect remains unknown.

  4. [Substantiation of a complex of radiation-hygienic approaches to the management of very low-level waste].

    PubMed

    Korenkov, I P; Lashchenova, T N; Shandala, N K

    2015-01-01

    In the article there are presented materials on radiation-hygienic approaches to the treatment of very low level radioactive waste (VLLW) and industrial waste containing radionuclides. There is done detailed information on radiation-hygienic principles and criteria for the assurance ofradiation safety in the collection, transportation, storage and processing of VLLW as a category of radioactive waste.. Particular attention is paid to the problem of designing VLLW landfill site choice, system of radiation monitoring in operation and decommissioning of the landfill. There are presented data about the criteria for the release of VLLW buried at the site, from regulatory control. Also there are considered in detail the radiation-hygienic requirements for radiation safety of industrial waste containing radionuclides for which there is assumed unlimited and limited use of solid materials in economic activity, based on the requirements ofthe revised Basic Sanitary Rules for Radiation Safety - 99/2010. There are considered basic requirements for the organization of industrial waste landfill. As an example, there-are presented the hygiene requirements for industrial waste management and results of waste categorization in Northern Federal Enterprise for Radioactive Waste Management.

  5. Surface ionisation of molecular H2 and atomic H Rydberg states at doped silicon surfaces

    NASA Astrophysics Data System (ADS)

    Sashikesh, G.; So, E.; Ford, M. S.; Softley, T. P.

    2014-09-01

    The detection of ions or electrons from the surface ionisation of molecular H2 and atomic H Rydberg states incident at doped Si surfaces is investigated experimentally to analyse the effect of the dopant charge distribution on the surface-ionisation processes. In both experimental studies, the molecular H2 and atomic H Rydberg states are generated via two-colour vacuum ultraviolet--ultraviolet (VUV-UV) resonant excitation. For H2, various Stark states of the N+ = 2, n = 17 manifold are populated in the presence of an electric field. The variation of the observed surface-ionisation signal with surface dopant concentration and type, shows similar characteristics for all the Stark states. A comparison is made between these ion-detected surface-ionisation profiles and those obtained via electron detection. Different trends as a function of dopant concentration and type are observed for the two cases, explained by the greater effect of surface charges on the post-ionisation ion trajectory compared to the electron trajectory. For the atomic-H Rydberg states with principal quantum number ? populated in the absence of a Stark field, the observed behaviour is similar to the interaction of molecular H2 Rydberg states at the same surfaces, and these measurements confirm that the observed effects are attributable to the nature of the target surface rather than the specific atomic or molecular Rydberg species.

  6. Ionising irradiation alters the dynamics of human long interspersed nuclear elements 1 (LINE1) retrotransposon.

    PubMed

    Tanaka, Atsushi; Nakatani, Youko; Hamada, Nobuyuki; Jinno-Oue, Atsushi; Shimizu, Nobuaki; Wada, Seiichi; Funayama, Tomoo; Mori, Takahisa; Islam, Salequl; Hoque, Sheikh Ariful; Shinagawa, Masahiko; Ohtsuki, Takahiro; Kobayashi, Yasuhiko; Hoshino, Hiroo

    2012-09-01

    It is important to identify the mechanism by which ionising irradiation induces various genomic alterations in the progeny of surviving cells. Ionising irradiation activates mobile elements like retrotransposons, although the mechanism of its phenomena consisting of transcriptions and insertions of the products into new sites of the genome remains unclear. In this study, we analysed the effects of sparsely ionising X-rays and densely ionising carbon-ion beams on the activities of a family of active retrotransposons, long interspersed nuclear elements 1 (L1). We used the L1/reporter knock-in human glioma cell line, NP-2/L1RP-enhanced GFP (EGFP), that harbours full-length L1 tagged with EGFP retrotransposition detection cassette (L1RP-EGFP) in the chromosomal DNA. X-rays and carbon-ion beams similarly increased frequencies the transcription from L1RP-EGFP and its retrotransposition. Short-sized de novo L1RP-EGFP insertions with 5'-truncation were induced by X-rays, while full-length or long-sized insertions (>5 kb, containing ORF1 and ORF2) were found only in cell clones irradiated by the carbon-ion beams. These data suggest that X-rays and carbon-ion beams induce different length of de novo L1 insertions, respectively. Our findings thus highlight the necessity to investigate the mechanisms of mutations caused by transposable elements by ionising irradiation.

  7. 10 CFR 840.4 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite. 840.4 Section 840.4 Energy DEPARTMENT OF ENERGY EXTRAORDINARY NUCLEAR OCCURRENCES § 840.4 Criterion I—Substantial discharge of radioactive material...

  8. 10 CFR 840.4 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite. 840.4 Section 840.4 Energy DEPARTMENT OF ENERGY EXTRAORDINARY NUCLEAR OCCURRENCES § 840.4 Criterion I—Substantial discharge of radioactive material...

  9. 10 CFR 840.4 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite. 840.4 Section 840.4 Energy DEPARTMENT OF ENERGY EXTRAORDINARY NUCLEAR OCCURRENCES § 840.4 Criterion I—Substantial discharge of radioactive material...

  10. 10 CFR 840.4 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite. 840.4 Section 840.4 Energy DEPARTMENT OF ENERGY EXTRAORDINARY NUCLEAR OCCURRENCES § 840.4 Criterion I—Substantial discharge of radioactive material...

  11. 10 CFR 840.4 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite. 840.4 Section 840.4 Energy DEPARTMENT OF ENERGY EXTRAORDINARY NUCLEAR OCCURRENCES § 840.4 Criterion I—Substantial discharge of radioactive material...

  12. Photooxidation and antioxidant responses in the earthworm Amynthas gracilis exposed to environmental levels of ultraviolet B radiation.

    PubMed

    Chuang, Shu-Chun; Chen, Jiun-Hong

    2013-03-01

    Ultraviolet (UV) radiation leads to photooxidation in various organisms. Our previous study demonstrated that ultraviolet B (UV-B) radiation is lethal for particular species of earthworms, but the mechanisms responsible for the lethality are unclear. In our current study, we investigated that ultraviolet light causes photooxidative damage and reduces antioxidant responses in the earthworm Amynthas gracilis. Intact earthworms and skin/muscle tissue extracts were exposed to UV-B radiation for in vivo and in vitro studies. Both in vitro and in vivo results showed that the products of photooxidative damage, MDA and H(2)O(2), increased after UV-B exposure. Glutathione peroxidase (GPx) and catalase were inhibited immediately after exposure to high doses (3000J/m(2)) of UV-B radiation in vivo. Catalase activity was increased following a low UV-B dose (500J/m(2)) in vivo, but decreased in response to all dosage levels in vitro. These data indicate that a relationship exists between UV-B induced damage and photooxidation and also that catalase and GPx act as important antioxidants to prevent photooxidation. According to these data, A. gracilis exhibits high sensitivity to environmental levels of UV-B. Therefore, A. gracilis represents a sensitive and cost-effective model organism for investigations of UV-radiation damage and environmental UV stress.

  13. Health effects in women exposed to low levels of ionizing radiation

    SciTech Connect

    Fabrikant, J.I.

    1982-06-01

    There are three delayed health effects of radiation which appear at the present time to have importance to women in radiation protection. These are: (1) the probability of cancer-induction at low doses and low-dose rates; (2) the consideration of those cancers in women, notably the breast and the thyroid, attributable to radiation exposure; and (3) the probability of induction of developmental abnormalities in the newborn following low-dose exposure in utero. The bases for the concern over these effects are discussed. (ACR)

  14. Report on policy and activities concerning public awareness of health effects of low-level radiation

    SciTech Connect

    1986-11-01

    In the summer of 1986, the Executive Committee authorized a study limited to determining policy and practices relevant to dissemination of information to the public on radiation health effects in three federal agencies. This report summarizes findings on two broad questions related to the communication issue: What, if any, are the policies under which federal agencies operate in disseminating information on health effects of radiation and what are the current programs and activities designed to provide the public information on health effects of radiation.

  15. Impact ionisation mass spectrometry of polypyrrole-coated pyrrhotite microparticles

    NASA Astrophysics Data System (ADS)

    Hillier, Jon K.; Sternovsky, Zoltan; Armes, Steven P.; Fielding, Lee A.; Postberg, Frank; Bugiel, Sebastian; Drake, Keith; Srama, Ralf; Kearsley, Anton T.; Trieloff, Mario

    2014-07-01

    Cation and anion impact ionization mass spectra of polypyrrole-coated pyrrhotite cosmic dust analogue particles are analysed over a range of cosmically relevant impact speeds. Spectra with mass resolutions of 150-300 were generated by hypervelocity impacts of charged particles, accelerated to up to 37 km s-1 in a Van de Graaff electrostatic accelerator, onto a silver target plate in the Large Area Mass Analyzer (LAMA) spectrometer. Ions clearly indicative of the polypyrrole overlayer are identified at masses of 93, 105, 117, 128 and 141 u. Organic species, predominantly derived from the thin (20 nm) polypyrrole layer on the surface of the particles, dominate the anion spectra even at high (>20 km s-1) impact velocities and contribute significantly to the cation spectra at velocities lower than this. Atomic species from the pyrrhotite core (Fe and S) are visible in all spectra at impact velocities above 6 km s-1 for 56Fe+, 9 km s-1 for 32S+ and 16 km s-1 for 32S- ions. Species from the pyrrhotite core are also frequently visible in cation spectra at impact speeds at which surface ionisation is believed to dominate (<10 km s-1), although the large number of organic peaks complicates the identification of characteristic molecular species. A thin oxidised surface layer on the pyrrhotite particles is indicated by weak spectral features assigned to iron oxides and iron oxy-hydroxides, although the definitive identification of sulfates and hydrated sulfates from the oxidation process was not possible. Silver was confirmed as an excellent choice for the target plate of an impact ionization mass spectrometer, as it provided a unique isotope signature for many target-projectile cluster peaks at masses above 107-109 u. The affinity of Ag towards a dominant organic fragment ion (CN-) derived from fragmentation of the polypyrrole component led to molecular cluster formation. This resulted in an enhanced sensitivity to a particular particle component, which may be of great use

  16. Theoretical and experimental investigation of high-level radiation sources used to model a heat input

    NASA Astrophysics Data System (ADS)

    Gradov, V. M.; Petrikevich, B. B.; Shcherbakov, A. A.

    1980-03-01

    This paper examines high-intensity xenon-filled radiation sources for heat load simulation. A mathematical model of the discharge is proposed, and results of a theoretical and an experimental investigation are presented.

  17. Ionizing radiation effects on cells, organelles and tissues on proteome level.

    PubMed

    Tapio, Soile

    2013-01-01

    This chapter will review the proteome alterations induced by ionizing radiation in cellular systems or using animal models with whole body or localised exposure. The recent developments in qualitative and quantitative proteome analysis using formalin-fixed paraffin-embedded material from radiobiology archives will be illustrated. The development of promising protein targets to be used as radiation biomarkers in future molecular epidemiology studies is described.

  18. Evaluation of spontaneous DNA damage in lymphocytes of healthy adult individuals from high-level natural radiation areas of Kerala in India.

    PubMed

    Kumar, P R Vivek; Cheriyan, V D; Seshadri, M

    2012-05-01

    Inhabitants of the high-level natural radiation areas (>1 mSv year(-1)) of Kerala in southwest India were evaluated for basal damage (spontaneous DNA strand breaks and alkali-labile sites) by the alkaline comet assay and oxidative DNA damage (ENDO III- and hOGG1-sensitive sites) by the enzyme-modified comet assay. Of the 67 adult male subjects studied, 45 were from high-level natural radiation areas and 22 subjects were from a nearby normal-level natural radiation area (≤1 mSv year(-1)). Basal damage due to the age and residential area (normal-level natural radiation area/high-level natural radiation areas) of the donors showed significant interaction (P < 0.001) when all subjects were analyzed using a general linear model (GLM). In subgroup analysis, basal damage increased with age in subjects from the normal-level natural radiation area (P = 0.02), while a significant negative correlation (P = 0.002) was observed in subjects from high-level natural radiation areas. Further, basal damage in elderly subjects from high-level natural radiation areas was significantly (P < 0.001) lower compared to the subjects from the normal-level natural radiation area. Oxidative DNA damage was not influenced by age, smoking habit or residential area in the entire sample. However, in a subgroup analysis, hOGG1-sensitive sites showed a significant increase with age in subjects from high-level natural radiation areas (P = 0.005). ENDO III-sensitive sites increased with natural radiation exposure in subjects from high-level natural radiation areas (P = 0.02), but when stratified according to smoking, a significant increase was observed only in smokers (P = 0.01). To the best of our knowledge, this is the first study on basal and oxidative DNA damage in healthy adults of this population. However, our findings need more validation in a larger study population.

  19. An integrated two-level hierarchical system for decision making in radiation therapy based on fuzzy cognitive maps.

    PubMed

    Papageorgiou, Elpiniki I; Stylios, Chrysostomos D; Groumpos, Peter P

    2003-12-01

    The radiation therapy decision-making is a complex process that has to take into consideration a variety of interrelated functions. Many fuzzy factors that must be considered in the calculation of the appropriate dose increase the complexity of the decision-making problem. A novel approach introduces fuzzy cognitive maps (FCMs) as the computational modeling method, which tackles the complexity and allows the analysis and simulation of the clinical radiation procedure. Specifically this approach is used to determine the success of radiation therapy process estimating the final dose delivered to the target volume, based on the soft computing technique of FCMs. Furthermore a two-level integrated hierarchical structure is proposed to supervise and evaluate the radiotherapy process prior to treatment execution. The supervisor determines the treatment variables of cancer therapy and the acceptance level of final radiation dose to the target volume. Two clinical case studies are used to test the proposed methodology and evaluate the simulation results. The usefulness of this two-level hierarchical structure discussed and future research directions are suggested for the clinical use of this methodology.

  20. Energy levels, radiative rates and lifetimes for transitions in Br-like ions with 38 ⩽ Z ⩽ 42

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, Francis P.

    2014-12-01

    Energy levels and radiative rates for transitions in five Br-like ions (Sr IV, Y V, Zr VI, Nb VII and Mo VIII) are calculated with the general-purpose relativistic atomic structure package (grasp). Extensive configuration interaction has been included and results are presented among the lowest 31 levels of the 4s24p5, 4s24p44d and 4s4p6 configurations. Lifetimes for these levels have also been determined, although unfortunately no measurements are available with which to compare. However, recently theoretical results have been reported by Singh et al (2013 Phys. Scr. 88 035301) using the same grasp code. But their reported data for radiative rates and lifetimes cannot be reproduced and show discrepancies of up to five orders of magnitude with the present calculations.

  1. Chromosome aberration analysis in persons exposed to low-level radiation from the JCO criticality accident in Tokai-mura.

    PubMed

    Sasaki, M S; Hayata, I; Kamada, N; Kodama, Y; Kodama, S

    2001-09-01

    Chromosome aberrations were studied in peripheral blood lymphocytes of 43 persons who were exposed to low-level radiation of mixed neutrons and gamma-rays resulting from the JCO criticality accident. When the age-adjusted frequencies of dicentric and ring chromosomes were compared with the dose calibration curve established in vitro for 60Co gamma-rays as a reference radiation, a significant correlation was observed between the chromosomally estimated doses and the documented doses evaluated by physical means. The regression coefficient of the chromosomal doses against the documented doses, 1.47 +/- 0.33, indicates that the relative biological effectiveness of fission neutrons at low doses is considerably higher than that currently adopted in the radiation protection standard.

  2. Molybdic acid ionisation under hydrothermal conditions to 300 °C

    NASA Astrophysics Data System (ADS)

    Minubayeva, Z.; Seward, T. M.

    2010-08-01

    This UV spectrophotometric study was aimed at providing precise, experimentally derived thermodynamic data for the ionisation of molybdic acid (H 2MoO 4) from 30 to 300 °C and at equilibrium saturated vapour pressures. The determination of the equilibrium constants and associated thermodynamic parameters were facilitated by spectrophotometric measurements using a specially designed high temperature optical Ti-Pd flow-through cell with silica glass windows. The following van't Hoff isochore equations describe the temperature dependence of the first and second ionisation constants of molybdic acid up to 300 °C:

  3. A micro-gap, air-filled ionisation chamber as a detector for criticality accident dosimetry.

    PubMed

    Murawski, Ł; Zielczyński, M; Golnik, N; Gryziński, M A

    2014-10-01

    A micro-gap air-filled ionisation chamber was designed for criticality dosimetry. The special feature of the chamber is its very small gap between electrodes of only 0.3 mm. This prevents ion recombination at high dose rates and minimises the influence of gas on secondary particles spectrum. The electrodes are made of polypropylene because of higher content of hydrogen in this material, when compared with soft tissue. The difference between neutron and gamma sensitivity in such chamber becomes practically negligible. The chamber's envelope contains two specially connected capacitors, one for polarising the electrodes and the other for collecting the ionisation charge.

  4. BOREAS RSS-14 Level -3 Gridded Radiometer and Satellite Surface Radiation Images

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Nickeson, Jaime (Editor); Hodges, Gary; Smith, Eric A.

    2000-01-01

    The BOREAS RSS-14 team collected and processed GOES-7 and -8 images of the BOREAS region as part of its effort to characterize the incoming, reflected, and emitted radiation at regional scales. This data set contains surface radiation parameters, such as net radiation and net solar radiation, that have been interpolated from GOES-7 images and AMS data onto the standard BOREAS mapping grid at a resolution of 5 km N-S and E-W. While some parameters are taken directly from the AMS data set, others have been corrected according to calibrations carried out during IFC-2 in 1994. The corrected values as well as the uncorrected values are included. For example, two values of net radiation are provided: an uncorrected value (Rn), and a value that has been corrected according to the calibrations (Rn-COR). The data are provided in binary image format data files. Some of the data files on the BOREAS CD-ROMs have been compressed using the Gzip program. See section 8.2 for details. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  5. On the effect of different aerosol types on surface solar radiation levels over the region of Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Alexandri, Georgia; Georgoulias, Aristeidis K.; Kourtidis, Konstantinos; Meleti, Charikleia; Balis, Dimitris

    2014-05-01

    In this work, we examine the direct effect of different aerosol types on the surface solar radiation (SSR) levels in the region of Eastern Mediterranean. Simulations with the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model were performed using ground and satellite-based data as input. An IDL tool that "feeds" SBDART with the appropriate input data was developed allowing us to simulate SSR with a time step of 1 hour. Level-2 aerosol optical depth, cloud optical depth, cloud fraction, effective droplet radius, cloud top pressure, precipitable water and surface albedo data from MODIS, as well as ozone total column data from Earth Probe TOMS and OMI satellite sensors, coarse resolution cloud data from the ISCCP and single scattering albedo, asymmetry factor and Angström exponent sunphotometric data from the AERONET are used in our radiative transfer simulations. Simulations are performed over selected spots within Eastern Mediterranean for clear, liquid cloud and ice cloud covered skies and for different aerosol types (maritime, dust, anthropogenic, fine-mode natural). The optical properties of aerosols were determined using a combination of satellite, ground-based, model and reanalysis products. The aerosol direct radiative effect is defined as the difference between simulations done with and without the presence of aerosols. This research has been financed by EPAN II and PEP under the national action "Bilateral, multilateral and regional R&T cooperations" (AEROVIS Sino-Greek project).

  6. A rapid fish radiation associated with the last sea-level changes in southern Brazil: the silverside Odontesthes perugiae complex.

    PubMed Central

    Beheregaray, Luciano B; Sunnucks, Paul; Briscoe, David A

    2002-01-01

    Coastal freshwater fishes provide valuable models for studying the role of the last glaciations in promoting speciation. To date, the great majority of studies are of Northern Hemisphere taxa, and reflect the influence of vicariant events during, or prior to, the Pleistocene. Microsatellite markers and mitochondrial DNA sequences were used to investigate patterns of population divergence and evolutionary relationships in a freshwater group of silverside fishes (Odontesthes perugiae complex), endemic to the recently formed coastal plain of southern Brazil. Lacustrine morphotypes showed concordant patterns of genetic and morphological divergence consistent with the geographical history of the coastal plain. The results support the proposal of a silverside radiation chronologically shaped by the sea-level changes of the Pleistocene and Holocene. The radiating lineage comprises a minimum of three allopatric and two sympatric lacustrine species. Four species displayed extremely high levels of genetic variation and some of the most rapid speciation rates reported in fishes. These features were related to a marine-estuarine origin of the radiation. To the best of our knowledge, this study represents the first molecular phylogeographic survey of a coastal radiation in South America. PMID:11788038

  7. System level latchup mitigation for single event and transient radiation effects on electronics

    SciTech Connect

    Kimbrough, J.R.; Colella, N.J.

    1994-12-31

    A `blink` technique, analogous to a person blinking at a flash of bright light, is provided for mitigating the effects of single event current latchup and prompt pulse destructive radiation on a micro-electronic circuit. The system includes event detection means, power dump logic means, and energy limiting measures with autonomous recovery. The event detection means includes ionizing radiation pulse detection means for detecting a pulse of ionizing radiation and for providing at an output terminal thereof a detection signal indicative of the detection of a pulse of ionizing radiation or by ion-induced destructive latchup of a semiconductor device. The current sensing means is coupled to the power bus for determining an occurrence of excess current through the power bus caused by ionizing radiation. The power dump means includes power dump logic means having a first input terminal connected to the output terminal of the ionizing radiation pulse detection means and having a second input terminal connected to the output terminal of the current sensing means. The power dump logic means provides an output signal to the input terminal of the means for opening the power bus and the means for shorting the power bus to a ground potential to remove power from the power bus. The energy limiting mean with autonomous recovery includes means for opening the power bus and means for shorting the power bus to a ground potential. The means for opening the power bus and means for shorting the power bus to a ground potential includes a series FET and a shunt FET. The invention provides for self-contained sensing for latchup, first removal of power to protect latched components, and autonomous recovery to enable transparent operation of other system elements.

  8. System level latchup mitigation for single event and transient radiation effects on electronics

    DOEpatents

    Kimbrough, Joseph Robert; Colella, Nicholas John

    1997-01-01

    A "blink" technique, analogous to a person blinking at a flash of bright light, is provided for mitigating the effects of single event current latchup and prompt pulse destructive radiation on a micro-electronic circuit. The system includes event detection circuitry, power dump logic circuitry, and energy limiting measures with autonomous recovery. The event detection circuitry includes ionizing radiation pulse detection means for detecting a pulse of ionizing radiation and for providing at an output terminal thereof a detection signal indicative of the detection of a pulse of ionizing radiation. The current sensing circuitry is coupled to the power bus for determining an occurrence of excess current through the power bus caused by ionizing radiation or by ion-induced destructive latchup of a semiconductor device. The power dump circuitry includes power dump logic circuitry having a first input terminal connected to the output terminal of the ionizing radiation pulse detection circuitry and having a second input terminal connected to the output terminal of the current sensing circuitry. The power dump logic circuitry provides an output signal to the input terminal of the circuitry for opening the power bus and the circuitry for shorting the power bus to a ground potential to remove power from the power bus. The energy limiting circuitry with autonomous recovery includes circuitry for opening the power bus and circuitry for shorting the power bus to a ground potential. The circuitry for opening the power bus and circuitry for shorting the power bus to a ground potential includes a series FET and a shunt FET. The invention provides for self-contained sensing for latchup, first removal of power to protect latched components, and autonomous recovery to enable transparent operation of other system elements.

  9. System level latchup mitigation for single event and transient radiation effects on electronics

    DOEpatents

    Kimbrough, J.R.; Colella, N.J.

    1997-09-30

    A ``blink`` technique, analogous to a person blinking at a flash of bright light, is provided for mitigating the effects of single event current latchup and prompt pulse destructive radiation on a micro-electronic circuit. The system includes event detection circuitry, power dump logic circuitry, and energy limiting measures with autonomous recovery. The event detection circuitry includes ionizing radiation pulse detection means for detecting a pulse of ionizing radiation and for providing at an output terminal thereof a detection signal indicative of the detection of a pulse of ionizing radiation. The current sensing circuitry is coupled to the power bus for determining an occurrence of excess current through the power bus caused by ionizing radiation or by ion-induced destructive latchup of a semiconductor device. The power dump circuitry includes power dump logic circuitry having a first input terminal connected to the output terminal of the ionizing radiation pulse detection circuitry and having a second input terminal connected to the output terminal of the current sensing circuitry. The power dump logic circuitry provides an output signal to the input terminal of the circuitry for opening the power bus and the circuitry for shorting the power bus to a ground potential to remove power from the power bus. The energy limiting circuitry with autonomous recovery includes circuitry for opening the power bus and circuitry for shorting the power bus to a ground potential. The circuitry for opening the power bus and circuitry for shorting the power bus to a ground potential includes a series FET and a shunt FET. The invention provides for self-contained sensing for latchup, first removal of power to protect latched components, and autonomous recovery to enable transparent operation of other system elements. 18 figs.

  10. Outdoor 220Rn, 222Rn and terrestrial gamma radiation levels: investigation study in the thorium rich Fen Complex, Norway.

    PubMed

    Mrdakovic Popic, Jelena; Bhatt, Chhavi Raj; Salbu, Brit; Skipperud, Lindis

    2012-01-01

    The present study was done in the Fen Complex, a Norwegian area rich in naturally occurring radionuclides, especially in thorium ((232)Th). Measurement of radioactivity levels was conducted at the decommissioned iron (Fe) and niobium (Nb) mining sites (TENORM) as well as at the undisturbed wooded sites (NORM), all open for free public access. The soil activity concentrations of (232)Th (3280-8395 Bq kg(-1)) were significantly higher than the world and the Norwegian average values and exceeded the Norwegian screening level (1000 Bq kg(-1)) for radioactive waste, while radium ((226)Ra) was present at slightly elevated levels (89-171 Bq kg(-1)). Terrestrial gamma dose rates were also elevated, ranging 2.6-4.4 μGy h(-1). Based on long-term surveys, the air concentrations of thoron ((220)Rn) and radon ((222)Rn) reached 1786 and 82 Bq m(-3), respectively. Seasonal variation in the outdoor gamma dose rates and Rn concentrations was confirmed. Correlation analyses showed a linear relationship between air radiation levels and the abundance of (232)Th in soil. The annual outdoor effective radiation doses for humans (occupancy 5 h day(-1)) were estimated to be in the range of 3.0-7.7 mSv, comparable or higher than the total average (summarized indoor and outdoor) exposure dose for the Norwegian population (2.9 mSv year(-1)). On the basis of all obtained results, this Norwegian area should be considered as enhanced natural radiation area (ENRA).

  11. Determination of Cd and Zn by isotope dilution-thermal ionisation mass spectrometry using a sequential analysis procedure.

    PubMed

    Ayoub, Ahmed S; McGaw, Brian A; Midwood, Andrew J

    2002-05-16

    Isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) was used to examine the certified Cd and Zn content of 4 Certified Reference Materials (CRMs); 2 soils: GBW07401 and GBW07405, 1 plant CRM060 and an animal tissue SRM1566a. The CRMs were chosen to be of contrasting origin and Cd:Zn content. Three digestion procedures were compared: (i) an open tube aqua regia procedure (ii) microwave digestion using Teflon bombs and (iii) hydrofluoric acid (HF) digestion using PTFE bombs. The Cd and Zn levels obtained using ID-TIMS all fell within the published certified range for the CRMs. This was the case regardless of the digestion procedure used, although HF digestion tended to yield marginally higher levels than the other procedures and in one instance, Cd in GBW07401, was significantly different (P<0.05) from the certified range. A filament loading procedure was developed, to allow sequential analysis of Cd and Zn on the same single filament during thermal ionisation mass spectrometry analysis. The sequential analysis technique was evaluated to ensure that Zn did not fractionate during Cd analysis and there was no inter-element interference. No marked difference in the precision and accuracy of the isotope ratio measurements were obtained from sequential element analyses on the same filament when compared to individual element analyses for a range of standard solutions or for sample digests. The most efficient procedure in terms of costs and productivity for future work of this kind would be a combination of microwave digestion and sequential analysis of Cd and Zn on the same filament.

  12. Study of the dosimetric characteristics of cosmic radiation at civil aviation altitudes.

    PubMed

    Ferrari, A; Pellicioni, M; Rancati, T

    2002-01-01

    The dependence of the doses on solar activity for intermediate levels of the solar modulation parameter has been studied by means of simulations carried out by the Monte Carlo transport code FLUKA. The vertical cut-off rigidities investigated lie between 0.4 and 6.1 GV. The calculated results show that the linear dependence proposed in a previous work, for the effective dose rate as a function of the solar modulation parameter, can be considered as an acceptable approximation. In addition, some dosimetric characteristics of cosmic radiation and some properties of the dosemeters in use for monitoring in the cosmic ray environment have been analysed with a view to simplifying measurements. The depth-dose curves in the ICRU sphere and the response of a tissue-equivalent ionisation chamber have been determined by the FLUKA code for a number of cosmic ray spectra On the basis of the calculated results, it is concluded that a value of the depth. d, which would make the ambient dose equivalent a conservative predictor of the effective dose, cannot be specified for cosmic radiation. However, the operational quantity can be useful in order to verify the predictions of Monte Carlo calculations. It is demonstrated that a crude approximation of the ambient dose equivalent could be obtained by multiplying by 2 the absorbed dose measured by a tissue-equivalent ionisation chamber with wall thickness of 10 mm.

  13. Measurements of background radiation levels around Indian station Bharati, during 33rd Indian Scientific Expedition to Antarctica.

    PubMed

    Bakshi, A K; Prajith, Rama; Chinnaesakki, S; Pal, Rupali; Sathian, Deepa; Dhar, Ajay; Selvam, T Palani; Sapra, B K; Datta, D

    2017-02-01

    A comprehensive measurement of radioactivity concentrations of the primordial radionuclides (238)U, (232)Th and (40)K and their decay products in the soil samples collected from the sites of Indian research stations, Bharati and Maitri, at Antarctica was carried out using gamma spectrometric method. The activity concentrations in the soil samples of Bharati site were observed to be few times higher than of Maitri site. The major contributor to radioactivity content in the soil at Bharati site is (232)Th radionuclide in higher concentration. The gamma radiation levels based on the measured radioactivity of soil samples were calculated using the equation given in UNSCEAR 2000. The calculated radiation levels were compared with the measured values and found to correlate reasonably well. The study could be useful for the scientists working at Antarctica especially those at Indian station to take decision to avoid areas with higher radioactivity before erecting any facility for long term experiment or use.

  14. Multi-Level Effects of Low Dose Rate Ionizing Radiation on Southern Toad, Anaxyrus [Bufo] terrestris

    PubMed Central

    Stark, Karolina; Scott, David E.; Tsyusko, Olga; Coughlin, Daniel P.; Hinton, Thomas G.

    2015-01-01

    Despite their potential vulnerability to contaminants from exposure at multiple life stages, amphibians are one of the least studied groups of vertebrates in ecotoxicology, and research on radiation effects in amphibians is scarce. We used multiple endpoints to assess the radiosensitivity of the southern toad (Anaxyrus [Bufo] terrestris) during its pre-terrestrial stages of development –embryonic, larval, and metamorphic. Toads were exposed, from several hours after oviposition through metamorphosis (up to 77 days later), to four low dose rates of 137Cs at 0.13, 2.4, 21, and 222 mGy d-1, resulting in total doses up to 15.8 Gy. Radiation treatments did not affect hatching success of embryos, larval survival, or the length of the larval period. The individual family variation in hatching success of embryos was larger than the radiation response. In contrast, newly metamorphosed individuals from the higher dose-rate treatments had higher mass and mass/length body indices, a measure which may relate to higher post-metamorphic survival. The increased mass and index at higher dose rates may indicate that the chronic, low dose rate radiation exposures triggered secondary responses. Additionally, the increases in growth were linked to a decrease in DNA damage (as measured by the Comet Assay) in red blood cells at a dose rate of 21 mGy d-1 and a total dose of 1.1 Gy. In conclusion, the complex effects of low dose rates of ionizing radiation may trigger growth and cellular repair mechanisms in amphibian larvae. PMID:25927361

  15. Observed instantaneous cirrus radiative effect on surface-level shortwave and longwave irradiances

    NASA Astrophysics Data System (ADS)

    Dupont, Jean-Charles; Haeffelin, Martial

    2008-11-01

    Data collected at the SIRTA Observatory, 20 km south of Paris, are analyzed to determine the instantaneous surface cloud radiative effect (CRE) induced by cirrus clouds. CRE is here defined as the difference between overcast-sky and clear-sky surface radiative fluxes obtained by ground-based measurement of broadband fluxes and clear-sky parametric models, respectively. Clear-sky periods detected by a double threshold based on lidar and radiative fluxes analysis show a root mean square error for clear-sky models smaller than 6.5 W m-2 for shortwave flux and 4 W m-2 for longwave flux. Over 100 h in 2003-2006 characterized by homogeneous overcast cirrus clouds are analyzed. Fifty percent of this cirrus population is subvisible and semitransparent, that is, with optical thickness less than 0.3. The mean surface shortwave cirrus cloud radiative effect (CRESW) is found near -50 W m-2. We establish the relationship between CRESW and cirrus optical thickness (COT) to be about -90 W m-2 per unit of COT. This SW sensitivity ranges from -80 W m-2 COT-1 to -100 W m-2 COT-1 for turbid to pristine atmospheres, respectively. We also establish the relationship between surface longwave cloud radiative effect (CRELW) and the irradiance emitted by the cirrus cloud derived from cloud infrared emissivity and cloud temperature. The average surface CRELW is about +5 W m-2. CRELW is found to be about 10% of the cloud irradiance. This LW effect ranges from 5 to 15% of the cirrus irradiance depending on atmospheric humidity for the wet and dry atmosphere, respectively.

  16. Multi-Level Effects of Low Dose Rate Ionizing Radiation on Southern Toad, Anaxyrus [Bufo] terrestris.

    PubMed

    Stark, Karolina; Scott, David E; Tsyusko, Olga; Coughlin, Daniel P; Hinton, Thomas G

    2015-01-01

    Despite their potential vulnerability to contaminants from exposure at multiple life stages, amphibians are one of the least studied groups of vertebrates in ecotoxicology, and research on radiation effects in amphibians is scarce. We used multiple endpoints to assess the radiosensitivity of the southern toad (Anaxyrus [Bufo] terrestris) during its pre-terrestrial stages of development -embryonic, larval, and metamorphic. Toads were exposed, from several hours after oviposition through metamorphosis (up to 77 days later), to four low dose rates of 137Cs at 0.13, 2.4, 21, and 222 mGy d-1, resulting in total doses up to 15.8 Gy. Radiation treatments did not affect hatching success of embryos, larval survival, or the length of the larval period. The individual family variation in hatching success of embryos was larger than the radiation response. In contrast, newly metamorphosed individuals from the higher dose-rate treatments had higher mass and mass/length body indices, a measure which may relate to higher post-metamorphic survival. The increased mass and index at higher dose rates may indicate that the chronic, low dose rate radiation exposures triggered secondary responses. Additionally, the increases in growth were linked to a decrease in DNA damage (as measured by the Comet Assay) in red blood cells at a dose rate of 21 mGy d-1 and a total dose of 1.1 Gy. In conclusion, the complex effects of low dose rates of ionizing radiation may trigger growth and cellular repair mechanisms in amphibian larvae.

  17. Multi-level effects of low dose rate ionizing radiation on southern toad, Anaxyrus [Bufo] terrestris

    DOE PAGES

    Stark, Karolina; Scott, David E.; Tsyusko, Olga; ...

    2015-04-30

    Despite their potential vulnerability to contaminants from exposure at multiple life stages, amphibians are one of the least studied groups of vertebrates in ecotoxicology, and research on radiation effects in amphibians is scarce. We used multiple endpoints to assess the radiosensitivity of the southern toad (Anaxyrus [Bufo] terrestris) during its pre-terrestrial stages of development –embryonic, larval, and metamorphic. Toads were exposed, from several hours after oviposition through metamorphosis (up to 77 days later), to four low dose rates of ¹³⁷Cs at 0.13, 2.4, 21, and 222 mGy d⁻¹, resulting in total doses up to 15.8 Gy. Radiation treatments did notmore » affect hatching success of embryos, larval survival, or the length of the larval period. The individual family variation in hatching success of embryos was larger than the radiation response. In contrast, newly metamorphosed individuals from the higher dose-rate treatments had higher mass and mass/length body indices, a measure which may relate to higher post-metamorphic survival. The increased mass and index at higher dose rates may indicate that the chronic, low dose rate radiation exposures triggered secondary responses. Additionally, the increases in growth were linked to a decrease in DNA damage (as measured by the Comet Assay) in red blood cells at a dose rate of 21mGy d⁻¹ and a total dose of 1.1 Gy. In conclusion, the complex effects of low dose rates of ionizing radiation may trigger growth and cellular repair mechanisms in amphibian larvae.« less

  18. [The role of transcription factors in the response of mouse lymphocytes to low-level electromagnetic and laser radiations].

    PubMed

    Khrenov, M O; Cherenkov, D A; Glushkova, O V; Novoselova, T V; Lunin, S M; Parfeniuk, S B; Lysenko, E A; Novoselova, E G; Fesenko, E E

    2007-01-01

    The effects of low-intensity laser radiation (LILR, 632.8 nm, 0.2 mW/cm2) and low-intensity electromagnetic waves (LIEW, 8.15 - 18 GHz, 1 MW/cm2) on the production of transcription factors in lymphocytes from NMRI male mice were examined. The total level of NF-KB and its phosphorylated metabolite Phospho-NF-kappaB, as well as the regulatory protein IkappaB-alpha were determined in spleen lymphocytes subjected to laser or microwave radiations. The proteins were determined by immunoblotting. Laser light induced a lowering in the level of NF-kappaB and IkappaB-alpha. By contrast, irradiation with electromagnetic waves resulted in a significant increase in the amount of NF-kappaB and IkappaB-alpha. The phosphorylated form of NF-kappaB did not noticeably change under either of the two kinds of radiation. The results showed that electromagnetic waves activate the production of both NF-kappaB and the regulatory protein IkappaB-alpha and these data confirm the stress character of the response of spleen lymphocytes to low-level microwaves of the centimeter range.

  19. Radiation dose assessments to support evaluations of radiological control levels for recycling or reuse of materials and equipment

    SciTech Connect

    Hill, R.L.; Aaberg, R.L.; Baker, D.A.; Kennedy, W.E. Jr.

    1995-07-01

    Pacific Northwest Laboratory is providing Environmental Protection Support and Assistance to the USDOE, Office of Environmental Guidance. Air, Water, and Radiation Division. As part of this effort, PNL is collecting data and conducting technical evaluations to support DOE analyses of the feasibility of developing radiological control levels for recycling or reuse of metals, concrete, or equipment containing residual radioactive contamination from DOE operations. The radiological control levels will be risk-based, as developed through a radiation exposure scenario and pathway analysis. The analysis will include evaluation of relevant radionuclides, potential mechanisms of exposure, and both health and non-health-related impacts. The main objective of this report is to develop a methodology for establishing radiological control levels for recycle or reuse. This report provides the results of the radiation exposure scenario and pathway analyses for 42 key radionuclides generated during DOE operations that may be contained in metals or equipment considered for either recycling or reuse. The scenarios and information developed by the IAEA. Application of Exemption Principles to the Recycle and Reuse of Materials from Nuclear Facilities, are used as the initial basis for this study. The analyses were performed for both selected worker populations at metal smelters and for the public downwind of a smelter facility. Doses to the public downwind were estimated using the US (EPA) CAP88-PC computer code with generic data on atmospheric dispersion and population density. Potential non-health-related effects of residual activity on electronics and on film were also analyzed.

  20. Annealing of GaSb Single Crystals in Ionised Hydrogen Atmosphere

    DTIC Science & Technology

    2001-01-01

    and Applications 46 of Single Crystals, Antoni Rogaski, Krzysztof Adamiec, Pawel Madejczyk, Editors, Proceedings of SPIE Vol. 4412 (2001) © 2001...1-50 hours. Hydrogen ionised by means of a deuterium lamp flew through this annealing reactor. After cooling the quartz ampoule, the carrier

  1. Examining Pre-Service Teachers' Use of Atomic Models in Explaining Subsequent Ionisation Energy Values

    ERIC Educational Resources Information Center

    Wheeldon, Ruth

    2012-01-01

    Chemistry students' explanations of ionisation energy phenomena often involve a number of non-scientific or inappropriate ideas being used to form causality arguments. Research has attributed this to many science teachers using these ideas themselves (Tan and Taber, in "J Chem Educ" 86(5):623-629, 2009). This research extends this work by…

  2. Identification of carbohydrates by matrix-free material-enhanced laser desorption/ionisation mass spectrometry.

    PubMed

    Hashir, Muhammad Ahsan; Stecher, Guenther; Bakry, Rania; Kasemsook, Saowapak; Blassnig, Bernhard; Feuerstein, Isabel; Abel, Gudrun; Popp, Michael; Bobleter, Ortwin; Bonn, Guenther K

    2007-01-01

    Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) is a sensitive mass spectrometric technique which utilises acidic materials as matrices for laser energy absorption, desorption and ionisation of analytes. These matrix materials produce background signals particularly in the low-mass range and make the detection and identification of small molecules difficult and nearly impossible. To overcome this problem this paper introduces matrix-free material-enhanced laser desorption/ionisation mass spectrometry (mf-MELDI-MS) for the screening and analysis of small molecules such as carbohydrates. For this purpose, 4,4'-azo-dianiline was immobilised on silica gel enabling the absorption of laser energy sufficient for successful desorption and ionisation of low molecular weight compounds. The particle and pore sizes, the solvent system for suspension and the sample preparation procedures have been optimised. The newly synthesised MELDI material delivered excellent spectra with regard to signal-to-noise ratio and detection sensitivity. Finally, wheat straw degradation products and Salix alba L. plant extracts were analysed proving the high performance and excellent behaviour of the introduced material.

  3. Mysteries of LiF TLD response following high ionisation density irradiation: nanodosimetry and track structure theory, dose response and glow curve shapes.

    PubMed

    Horowitz, Y; Fuks, E; Datz, H; Oster, L; Livingstone, J; Rosenfeld, A

    2011-06-01

    Three outstanding effects of ionisation density on the thermoluminescence (TL) mechanisms giving rise to the glow peaks of LiF:Mg,Ti (TLD-100) are currently under investigation: (1) the dependence of the heavy charged particle (HCP) relative efficiency with increasing ionisation density and the effectiveness of its modelling by track structure theory (TST), (2) the behaviour of the TL efficiency, f(D), as a function of photon energy and dose. These studies are intended to promote the development of a firm theoretical basis for the evaluation of relative TL efficiencies to assist in their application in mixed radiation fields. And (3) the shape of composite peak 5 in the glow curve for various HCP types and energies and following high-dose electron irradiation, i.e. the ratio of the intensity of peak 5a to peak 5. Peak 5a is a low-temperature satellite of peak 5 arising from electron-hole capture in a spatially correlated trapping centre/luminescent centre (TC/LC) complex that has been suggested to possess a potential as a solid-state nanodosemeter due to the preferential electron/hole population of the TC/LC at high ionisation density. It is concluded that (1) the predictions of TST are very strongly dependent on the choice of photon energy used in the determination of f(D); (2) modified TST employing calculated values of f(D) at 2 keV is in agreement with 5-MeV alpha particle experimental results for composite peak 5 but underestimates the 1.5-MeV proton relative efficiencies. Both the proton and alpha particle relative TL efficiencies of the high-temperature TL (HTTL) peaks 7 and 8 are underestimated by an order of magnitude suggesting that the HTTL efficiencies are affected by other factors in addition to radial electron dose; (3) the dose-response supralinearity of peaks 7 and 8 change rapidly with photon energy: this behaviour is explained in the framework of the unified interaction model as due to a very strong dependence on photon energy of the relative

  4. Medical-biological aspects of radiation effects in Daphnia magna

    NASA Astrophysics Data System (ADS)

    Sarapultseva, E.; Uskalova, D.; Savina, N.; Ustenko, K.

    2017-01-01

    We have shown that γ-irradiation at doses of 100 and 1000 mGy significantly compromised fecundity and reproductive success of the directly exposed D. magna. These effects were also observed among the non-exposed first-generation progeny of irradiated parents, thus implying the manifestation of transgenerational effects in Daphnia. We have also shown that compromised viability of irradiated D. magna can be attributed cytotoxic effects of irradiation. It would therefore appear that the compromised viability may be attributed to the cytotoxic effects resulted from epigenetic changes affecting some metabolic pathways involved in detoxification of free-radicals. Additionally we have analyzed more distant progeny of irradiated at doses of 10, 100 and 1000 mGy Daphnia. Our data demonstrated that multicellular crustacean D. magna represent a very useful experimental model for analyse of long-term effects of ionising radiation at the organismal level.

  5. Six iterative reconstruction algorithms in brain CT: a phantom study on image quality at different radiation dose levels

    PubMed Central

    Olsson, M-L; Siemund, R; Stålhammar, F; Björkman-Burtscher, I M; Söderberg, M

    2013-01-01

    Objective: To evaluate the image quality produced by six different iterative reconstruction (IR) algorithms in four CT systems in the setting of brain CT, using different radiation dose levels and iterative image optimisation levels. Methods: An image quality phantom, supplied with a bone mimicking annulus, was examined using four CT systems from different vendors and four radiation dose levels. Acquisitions were reconstructed using conventional filtered back-projection (FBP), three levels of statistical IR and, when available, a model-based IR algorithm. The evaluated image quality parameters were CT numbers, uniformity, noise, noise-power spectra, low-contrast resolution and spatial resolution. Results: Compared with FBP, noise reduction was achieved by all six IR algorithms at all radiation dose levels, with further improvement seen at higher IR levels. Noise-power spectra revealed changes in noise distribution relative to the FBP for most statistical IR algorithms, especially the two model-based IR algorithms. Compared with FBP, variable degrees of improvements were seen in both objective and subjective low-contrast resolutions for all IR algorithms. Spatial resolution was improved with both model-based IR algorithms and one of the statistical IR algorithms. Conclusion: The four statistical IR algorithms evaluated in the study all improved the general image quality compared with FBP, with improvement seen for most or all evaluated quality criteria. Further improvement was achieved with one of the model-based IR algorithms. Advances in knowledge: The six evaluated IR algorithms all improve the image quality in brain CT but show different strengths and weaknesses. PMID:24049128

  6. Spectral Analyses and Radiation Exposures from Several Ground-Level Enhancement (GLE) Solar Proton Events: A Comparison of Methodologies

    NASA Technical Reports Server (NTRS)

    Atwell, William; Tylka, Allan; Dietrich, William; Badavi, Francis; Rojdev, Kristina

    2011-01-01

    Several methods for analyzing the particle spectra from extremely large solar proton events, called Ground-Level Enhancements (GLEs), have been developed and utilized by the scientific community to describe the solar proton energy spectra and have been further applied to ascertain the radiation exposures to humans and radio-sensitive systems, namely electronics. In this paper 12 GLEs dating back to 1956 are discussed, and the three methods for describing the solar proton energy spectra are reviewed. The three spectral fitting methodologies are EXP [an exponential in proton rigidity (R)], WEIB [Weibull fit: an exponential in proton energy], and the Band function (BAND) [a double power law in proton rigidity]. The EXP and WEIB methods use low energy (MeV) GLE solar proton data and make extrapolations out to approx.1 GeV. On the other hand, the BAND method utilizes low- and medium-energy satellite solar proton data combined with high-energy solar proton data deduced from high-latitude neutron monitoring stations. Thus, the BAND method completely describes the entire proton energy spectrum based on actual solar proton observations out to 10 GeV. Using the differential spectra produced from each of the 12 selected GLEs for each of the three methods, radiation exposures are presented and discussed in detail. These radiation exposures are then compared with the current 30-day and annual crew exposure limits and the radiation effects to electronics.

  7. Common strategic research agenda for radiation protection in medicine.

    PubMed

    2017-04-01

    Reflecting the change in funding strategies for European research projects, and the goal to jointly improve medical radiation protection through sustainable research efforts, five medical societies involved in the application of ionising radiation (European Association of Nuclear Medicine, EANM; European Federation of Organizations for Medical Physics. EFOMP; European Federation of Radiographer Societies, EFRS; European Society of Radiology, ESR; European Society for Radiotherapy and Oncology, ESTRO) have identified research areas of common interest and developed this first edition of the Common Strategic Research Agenda (SRA) for medical radiation protection. The research topics considered necessary and most urgent for effective medical care and efficient in terms of radiation protection are summarised in five main themes: 1. Measurement and quantification in the field of medical applications of ionising radiation 2. Normal tissue reactions, radiation-induced morbidity and long-term health problems 3. Optimisation of radiation exposure and harmonisation of practices 4. Justification of the use of ionising radiation in medical practice 5. Infrastructures for quality assurance The SRA is a living document; thus comments and suggestions by all stakeholders in medical radiation protection are welcome and will be dealt with by the European Alliance for Medical Radiation Protection Research (EURAMED) established by the above-mentioned societies.

  8. Estimation of {sup 237}U Level Density and Radiative Strength Functions from the (n-bar,{gamma}) Reaction

    SciTech Connect

    Sukhovoj, Anatoly M.; Khitrov, Valery A.; Maslov, Vladimir M.

    2009-01-28

    Intensity distribution of the primary {gamma}-transitions following resonance neutron capture in {sup 236}U about the mean value was approximated in different energy intervals of these quanta and neutrons. Extrapolation of the obtained functions to zero registration threshold of {gamma}-transitions allowed independent estimation of the expected level number of both parities for spin values J = 1/2, 3/2 and sum of radiative widths for both electric and magnetic gamma-transitions to levels with excitation energy up to {approx_equal}2.3 MeV.

  9. Natural widths and blackbody radiation induced shift and broadening of Rydberg levels in magnesium ions

    NASA Astrophysics Data System (ADS)

    Glukhov, Igor L.; Mokhnenko, Sergey N.; Nikitina, Elizaveta A.; Ovsiannikov, Vitaly D.

    2015-01-01

    Theoretical analysis is presented of the natural lifetimes and blackbody-radiation (BBR)-induced shifts and widths of Rydberg states with small and large angular momenta l. Asymptotic presentations in elementary functions are derived for matrix elements of bound-bound, bound-free and threshold radiative transitions from hydrogenic-type states with large angular momenta, applicable to both hydrogen-like and many-electron atoms and ions. For states with small angular momenta two numerical methods based on the quantum defects were used and corresponding data are compared with one another and with the most reliable data of the literature. Asymptotic approximations are derived for natural lifetimes, thermal shifts and broadening of Rydberg states of small and high l and principal quantum numbers n ≫ 1.

  10. Development of UV-B screening compounds in response to variation in ambient levels of UV-B radiation

    NASA Astrophysics Data System (ADS)

    Sullivan, Joe H.; Xu, Chenping; Gao, Wei; Slusser, James R.

    2005-08-01

    The induction of UV-B screening compounds in response to exposure to UV-B radiation is a commonly reported response and is generally considered to be an adaptive response of plants for protection from UVinduced damage. However, a number of questions remain to be answered including the importance of qualitative and localization differences among species in providing protection, indirect consequences of changes in leaf secondary chemistry on ecological processes and the dose response of metabolite accumulation. In this study we utilized UV monitoring data provided on site by the USDA UV-B Monitoring and Research Program to monitor the changes in UV-screening compounds in soybeans under a range of UV-B levels due to natural variation in ambient UV-B radiation. Soybean cultivars Essex, Clark and Clark-magenta, an isoline of Clark that produces minimal levels of flavonols, were grown beneath shelters covered either with polyester to block most UV-B radiation or teflon which is nearly transparent in the UV range and harvested at regular intervals for pigment and protein analysis. Daily levels of weighted UV-B varied from <1 to >7 kJ m-2. Increases in UV-screening compounds showed a positive dose response to UV-B radiation in all cultivars with Essex showing the steepest dose response. UV-A also induced screening compounds in all species The hydroxycinnimates of the magenta isoline showed a steep dose response to UV-A and a rather constant (non dose specific) but small additional increment in response to UV-B. The Clark isoline, which produced primarily the flavonol quercetin, showed a dose response to UV-B intermediate between that of Clark-magenta and Essex. All three cultivars show similar tolerance to UV-B in field conditions indicating that UV-induced pigment production is adequate to protect them from excessive UV-B damage.

  11. Applying spaceborne reflectivity measurements for calculation of the solar ultraviolet radiation at ground level

    NASA Astrophysics Data System (ADS)

    den Outer, P. N.; van Dijk, A.; Slaper, H.; Lindfors, A. V.; De Backer, H.; Bais, A. F.; Feister, U.; Koskela, T.; Josefsson, W.

    2012-12-01

    Long-term analysis of cloud effects on ultraviolet (UV) radiation on the ground using spaceborne observations requires the use of instruments that have operated consecutively. The longest data record can be built from the reflectivity measurements produced by the instruments Total Ozone Mapping Spectrometers (TOMS) flown on Nimbus 7 from 1979 to 1992, TOMS on Earth Probe from 1996 to 2005, and the Ozone Monitoring Instrument (OMI) flown on EOS Aura since 2004. The reflectivity data produced by TOMS on Earth Probe is only included until 2002. A comparison is made with cloud effects inferred from ground-based pyranometer measurements at over 83 World Radiation Data Centre stations. Modelled UV irradiances utilizing the standard reflectivity are compared with measurements of UV irradiances at eight European low-elevation stations. The reflectivity data of the two TOMS instruments shows a consistent agreement, and the required corrections are of low percentage, i.e. 2-3%. In contrast, the reflectivity product of OMI requires correction of 7-10%, and a solar angle dependency therein is more pronounced. These corrections were inferred from a comparison with pyranometer data, and tested using the UV measurements. The average reduction of UV radiation due to clouds for all sites together indicates a small trend: a diminishing cloudiness, in line with ground-based UV observations. Uncorrected implementation of the reflectivity data would have indicated the opposite. An optimal area was established for reflectivity data for the calculation of daily sums of UV radiation. It measures approximately 1.25° in latitudinal direction for square-shaped areas overhead the ground-based UV stations. Such an area can be traversed within 5 to 7 h at the average wind speeds found for the West European continent.

  12. Theoretical and experimental investigation of high-level radiation sources used to model a heat input

    NASA Astrophysics Data System (ADS)

    Gradov, V. M.; Petrikevich, B. B.; Shcherbakov, A. A.

    1980-09-01

    A mathematical model of a wall-stabilized discharge is proposed for calculating the characteristics of high-intensity radiation sources used in high-temperature testing of materials and structures. The proposed model takes into consideration a number of processes and their effect on the total plasma absorption coefficient. These include photoionization of Xe atoms and ions and Xe bremsstrahlung. Theoretical calculations are verified by experiments carried out with a xenon arc lamp.

  13. Assessment of radiofrequency radiation within the vicinity of some GSM base stations in Ghana.

    PubMed

    Deatanyah, P; Amoako, J K; Fletcher, J J; Asiedu, G O; Adjei, D N; Dwapanyin, G O; Amoatey, E A

    2012-08-01

    A radiofrequency (RF) electromagnetic radiation safety survey had been carried out at public access points in 46 towns with 76 Global Systems for Mobile communication cell sites in two major cities in Ghana. The objective was to determine the levels of RF field in residential areas, schools and market places, and compare the measured results with the guidelines set by the International Commission of Non-Ionising Radiation (ICNIRP). Measurements were made with log-periodic antenna coupled with spectrum analyzer. The results varied from 0.85 to 1.07 mW m(-2) and 0.78 to 1.19 mW m(-2) for the transmission frequencies of 900 and 1800 MHz, respectively. The result generally shows a compliance with the ICNIRP limit of 0.024 % but was 108 times higher than a similar survey carried out in Ghana 2 y ago.

  14. Levels of thoron and progeny in high background radiation area of southeastern coast of Odisha, India.

    PubMed

    Ramola, R C; Gusain, G S; Rautela, B S; Sagar, D V; Prasad, G; Shahoo, S K; Ishikawa, T; Omori, Y; Janik, M; Sorimachi, A; Tokonami, S

    2012-11-01

    Exposure to radon, (222)Rn, is assumed to be the most significant source of natural radiation to human beings in most cases. It is thought that radon and its progeny are major factors that cause cancer. The presence of thoron, (220)Rn, was often neglected because it was considered that the quantity of thoron in the environment is less than that of radon. However, recent studies have shown that a high thoron concentration was found in some regions and the exposure to (220)Rn and its progeny can equal or several time exceed that of (220)Rn and its progeny. The results of thoron and its progeny measurements in the houses of high background radiation area (HBRA) of the southeastern coast of Odisha, India presented here. This area is one of the high background radiation areas in India with a large deposit of monazite sand which is the probable source of thoron. Both active and passive methods were employed for the measurement of thoron and its progeny in cement, brick and mud houses in the study area. Thoron concentration was measured using RAD-7 and Raduet. A CR-39 track detector was employed for the measurement of environmental thoron progeny, both in active and passive modes. Thoron and its progeny concentrations were found to be comparatively high in the area. A comparison between the results obtained with various techniques is presented in this paper.

  15. Performance study and influence of radiation emission energy and soil contamination level on γ-radiation shielding of stabilised/solidified radionuclide-polluted soils.

    PubMed

    Falciglia, Pietro P; Puccio, Valentina; Romano, Stefano; Vagliasindi, Federico G A

    2015-05-01

    This work focuses on the stabilisation/solidification (S/S) of radionuclide-polluted soils at different (232)Th levels using Portland cement alone and with barite aggregates. The potential of S/S was assessed applying a full testing protocol and calculating γ-radiation shielding (γRS) index, that included the measurement of soil radioactivity before and after the S/S as a function of the emission energy and soil contamination level. The results indicate that setting processes are strongly dependent on the contaminant concentration, and for contamination level higher than 5%, setting time values longer than 72 h. The addition of barite aggregates to the cement gout leads to a slight improvement of the S/S performance in terms of durability and contaminant leaching but reduces the mechanical resistance of the treated soils samples. Barite addition also causes an increase in the γ-rays shielding properties of the S/S treatment up to about 20%. Gamma-ray measurements show that γRS strongly depends on the energy, and that the radioactivity with the contamination level was governed by a linear trend, while, γRS index does not depend on the radionuclide concentration. Results allow the calculated γRS values and those available from other experiments to be applied to hazard radioactive soil contaminations.

  16. Integrated Radiation Transport and Nuclear Fuel Performance for Assembly-Level Simulations

    SciTech Connect

    Clarno, Kevin T; Hamilton, Steven P; Philip, Bobby; Berrill, Mark A; Sampath, Rahul S; Allu, Srikanth; Pugmire, Dave; Dilts, Gary; Banfield, James E

    2012-02-01

    The Advanced Multi-Physics (AMP) Nuclear Fuel Performance code (AMPFuel) is focused on predicting the temperature and strain within a nuclear fuel assembly to evaluate the performance and safety of existing and advanced nuclear fuel bundles within existing and advanced nuclear reactors. AMPFuel was extended to include an integrated nuclear fuel assembly capability for (one-way) coupled radiation transport and nuclear fuel assembly thermo-mechanics. This capability is the initial step toward incorporating an improved predictive nuclear fuel assembly modeling capability to accurately account for source-terms and boundary conditions of traditional (single-pin) nuclear fuel performance simulation, such as the neutron flux distribution, coolant conditions, and assembly mechanical stresses. A novel scheme is introduced for transferring the power distribution from the Scale/Denovo (Denovo) radiation transport code (structured, Cartesian mesh with smeared materials within each cell) to AMPFuel (unstructured, hexagonal mesh with a single material within each cell), allowing the use of a relatively coarse spatial mesh (10 million elements) for the radiation transport and a fine spatial mesh (3.3 billion elements) for thermo-mechanics with very little loss of accuracy. In addition, a new nuclear fuel-specific preconditioner was developed to account for the high aspect ratio of each fuel pin (12 feet axially, but 1 4 inches in diameter) with many individual fuel regions (pellets). With this novel capability, AMPFuel was used to model an entire 17 17 pressurized water reactor fuel assembly with many of the features resolved in three dimensions (for thermo-mechanics and/or neutronics), including the fuel, gap, and cladding of each of the 264 fuel pins; the 25 guide tubes; the top and bottom structural regions; and the upper and lower (neutron) reflector regions. The final, full assembly calculation was executed on Jaguar using 40,000 cores in under 10 hours to model over 162

  17. Integrated Radiation Transport and Nuclear Fuel Performance for Assembly-Level Simulations

    SciTech Connect

    Hamilton, Steven P; Clarno, Kevin T; Philip, Bobby; Berrill, Mark A; Sampath, Rahul S; Allu, Srikanth

    2012-01-01

    The Advanced Multi-Physics (AMP) Nuclear Fuel Performance code (AMPFuel) is focused on predicting the temperature and strain within a nuclear fuel assembly to evaluate the performance and safety of existing and advanced nuclear fuel bundles within existing and advanced nuclear reactors. AMPFuel was extended to include an integrated nuclear fuel assembly capability for (one-way) coupled radiation transport and nuclear fuel assembly thermo-mechanics. This capability is the initial step toward incorporating an improved predictive nuclear fuel assembly modeling capability to accurately account for source-terms, such as neutron flux distribution, coolant conditions and assembly mechanical stresses, of traditional (single-pin) nuclear fuel performance simulation. A novel scheme is introduced for transferring the power distribution from the Scale/Denovo (Denovo) radiation transport code (structured, Cartesian mesh with smeared materials within each cell) to AMPFuel (unstructured, hexagonal mesh with a single material within each cell), allowing the use of a relatively coarse spatial mesh (10 million elements) for the radiation transport and a fine spatial mesh (3.3 billion elements) for thermo-mechanics with very little loss of accuracy. With this novel capability, AMPFuel was used to model an entire 1717 pressurized water reactor fuel assembly with many of the features resolved in three dimensions (for thermo-mechanics and/or neutronics). A full assembly calculation was executed on Jaguar using 40,000 cores in under 10 hours to model over 160 billion degrees of freedom for 10 loading steps. The single radiation transport calculation required about 50% of the time required to solve the thermo-mechanics with a single loading step, which demonstrates that it is feasible to incorporate, in a single code, a high-fidelity radiation transport capability with a high-fidelity nuclear fuel thermo-mechanics capability and anticipate acceptable computational requirements. The

  18. Effects of radiation on the longitudinal trends of total serum cholesterol levels in the atomic bomb survivors.

    PubMed

    Wong, F L; Yamada, M; Sasaki, H; Kodama, K; Hosoda, Y

    1999-06-01

    The effects of radiation on the long-term trends of the total serum cholesterol levels of the Hiroshima and Nagasaki atomic bomb survivors were examined using data collected in the Adult Health Study over a 28-year period (1958-1986). The growth-curve method was used to model the longitudinal age-dependent changes in cholesterol levels. For each sex, temporal trends of cholesterol levels were characterized with respect to age, body mass index, city and birth year. We then examined whether the temporal trends differed by radiation dose. We showed that the mean growth curve of cholesterol levels for the irradiated subjects were significantly higher than that for the unirradiated subjects, and that the increase was greater for women than for men. No difference in dose response was detected between Hiroshima and Nagasaki. An increased mean level of cholesterol was evident for irradiated women in general, but a notable increase was apparent in males only for the youngest birth cohort of 1935-1945. The difference in the mean cholesterol levels between the irradiated and unirradiated subjects diminished past 70 years of age. It is not known whether this is due to natural progression or is an artifact of nonrandom variation in the rate of participation in the examinations. The maximum predicted increase at 1 Gy for women occurred at age 52 years for the 1930 cohort: 2.5 mg/dl (95% CI 1.6-3.3 mg/dl) for Hiroshima and 2.3 mg/dl (95% CI 1.5-3.1 mg/dl) for Nagasaki. The corresponding increase for men occurred at age 29 years for the 1940 cohort: 1.6 mg/dl (95% CI 0.4-2.8) for Hiroshima and 1.4 mg/dl (95% CI 0.3-2.6) for Nagasaki. Controlling for cigarette smoking did not alter the dose-response relationship. Although the difference in the mean growth curves of the irradiated and unirradiated groups was statistically significant, there was a considerable overlap in the individual growth curves of the two groups. The significant sex difference and the greater magnitude of

  19. Sensitivity to ionising radiation of lymphocytes from Huntington's chorea patients compared to controls

    SciTech Connect

    McGovern, D. ); Webb, T. )

    1982-06-01

    Blood samples were collected from 22 patients with Huntington's chorea and from 22 matched controls. Lymphocytes were separated from aliquots of each sample and cultures set up both from these and from further aliquots of whole blood. After 24 hours, half of each culture was subjected to X irradiation. Seventy-two hours later the percentages of live lymphocytes were estimated for each half of every culture and the viability ratio calculated for each sample. The lymphocytes derived from the patients with Huntington's chorea were found to be more susceptible to X irradiation than were the lymphocytes derived from controls. This was true both for whole blood and separated lymphocyte cultures. This susceptibility was found not to be the result of the main types of medication received by the patients. The small differences between viability ratios from patients and controls and the degree of overlap makes this test unsuitable for the prediction of asymptomatic carriers of the Huntington's chorea gene.

  20. Kinetics of the nitrogen first negative system excitation by ionising radiation

    SciTech Connect

    Khasenov, M U

    2005-12-31

    The rate constants of N{sub 2}{sup +}(B) quenching by nitrogen and helium and of two- and three-body charge exchange of He{sub 2}{sup +} on H{sub 2}, D{sub 2}, and Kr are measured from luminescence at the 0-0 transition of the first negative system of nitrogen in mixtures of helium and nitrogen with hydrogen, krypton or deuterium excited by alpha particles emitted by {sup 210}Po . (active media)

  1. Effect of low dose ionising radiation and nitric oxide on the state of animal blood system.

    PubMed

    Rodionova, N; Ganzha, O; Makovetska, L; Druzhyna, M; Muzalov, I; Mikhailenko, V

    2013-01-01

    Meta: doslidyty tryvalyj vplyv oksydu azotu ta malyh doz ionizujuchoi' radiacii' na stan systemy krovi. Materialy i metody. V eksperymenti vykorystani neinbredni samci-shhury vagoju 120–140 g. Tvaryny zaznavaly dii' riznyh chynnykiv: ingaljacii' oksydom azotu protjagom 30 dib (po 14 godyn na dobu), frakcionovanogo oprominennja malymy dozamy ionizujuchoi' radiacii' v sumarnij dozi 1,0 Gr ta i'h sumisnogo vplyvu. Doslidzhuvaly gematologichni, biohimichni ta biofizychni pokaznyky. Rezul'taty doslidzhennja. Pokazana radiozahysna dija oksydu azotu na morfofunkcional'ni pokaznyky, shho projavljalos' u reakcii' erytroi'dnogo pulu krovotvorennja i limfocytarnoi' lanky, u rivni porushennja okysnogo metabolizmu, znyzhenni vmistu atypovyh limfocytiv u peryferychnij krovi. Vysnovok. Oksyd azotu za sumisnoi' prolongovanoi' dii' z malymy dozamy ionizujuchogo vyprominjuvannja vyjavljaje radiozahysnyj efekt u systemi krovi. Kombinovana dija zaznachenyh chynnykiv, shho harakteryzujut'sja vplyvom na rizni metabolichni shljahy, pryzvodyt' do bil'sh efektyvnoi' adaptacii', nizh i'h okreme zastosuvannja.

  2. Combined effects of depleted uranium and ionising radiation on zebrafish embryos.

    PubMed

    Ng, C Y P; Pereira, S; Cheng, S H; Adam-Guillermin, C; Garnier-Laplace, J; Yu, K N

    2015-11-01

    In the environment, living organisms are exposed to a mixture of stressors, and the combined effects are deemed as multiple stressor effects. In the present work, the authors studied the multiple stressor effect in embryos of the zebrafish (Danio rerio) from simultaneous exposure to alpha particles and depleted uranium (DU) through quantification of apoptotic signals at 24 h post-fertilisation (hpf) revealed by vital dye acridine orange staining. In each set of experiments, dechorionated zebrafish embryos were divided into 4 groups, each having 10 embryos: Group (C) in which the embryos did not receive any further treatment; Group (IU) in which the embryos received an alpha-particle dose of 0.44 mGy at 5 hpf and were then exposed to 100 µg l(-1) of DU from 5 to 6 hpf; Group (I) in which the embryos received an alpha-particle dose of 0.44 mGy at 5 hpf and Group (U) in which the dechorionated embryos were exposed to 100 µg l(-1) of DU from 5 to 6 hpf. The authors confirmed that an alpha-particle dose of 0.44 mGy and a DU exposure for 1 h separately led to hormetic and toxic effects assessed by counting apoptotic signals, respectively, in the zebrafish. Interestingly, the combined exposure led to an effect more toxic than that caused by the DU exposure alone, so effectively DU changed the beneficial effect (hormesis) brought about by alpha-particle irradiation into an apparently toxic effect. This could be explained in terms of the promotion of early death of cells predisposed to spontaneous transformation by the small alpha-particle dose (i.e. hormetic effect) and the postponement of cell death upon DU exposure.

  3. The Effects of Ionising Radiation on MEMS Silicon Strain Gauges: Preliminary Background and Methodology

    DTIC Science & Technology

    2006-09-01

    are smaller and lighter than the current generation of detectors. The lower costs associated with mass - production of MEMS could also allow greater...development can measure the mass of an object down to 10-18 grams [1] or inertial motion on the order of nanometres [2], for example. Most significantly...an individual is typically encumbered by the weight and size of the current detectors. The lower costs associated with mass -production of MEMS could

  4. New laboratory atomic data for neutral, singly and doubly ionised iron group elements for astrophysics applications

    NASA Astrophysics Data System (ADS)

    Pickering, Juliet C.; Nave, Gillian; Liggins, Florence; Clear, Christian; Ruffoni, Matthew; Sansonetti, Craig

    2015-08-01

    We present new laboratory spectroscopic measurements to produce atomic data for astrophysically important species: neutral, singly and doubly ionised iron group elements.We use high resolution Fourier Transform Spectrometry (FTS) (resolving power up to 2x106 at 200nm) to measure atomic spectra, giving accurate line wavelengths (to a few parts in 108), atomic energy levels, hyperfine structure splitting and log gfs (accurate to a few %) (Ruffoni et al this meeting). These data are vital for astrophysical spectral analyses for: line identification, spectrum synthesis, elemental abundance determinations [eg 1], and disentangling of blends etc. It is not possible to theoretically calculate these atomic data to the accuracy needed for modern astrophysics applications.At Imperial College we have a unique visible-VUV FT spectrometer with short wavelength cut-off of 135nm. We supplement FTS data at shorter wavelengths with spectra recorded on the NIST 10.7m grating spectrograph (with phosphor image or photographic plates) and at longer wavelengths in the IR we use the NIST IR FT spectrometer.An elemental spectrum may contain thousands of spectral lines from the IR to VUV. We use these wavelengths to correct known atomic energy levels, and search for new atomic levels. The result is a classified linelist and accurate atomic energy levels.We present progress on iron group element atomic energy levels and wavelengths for V I and V II [2,3], Co III [4], Cr I, Mn I and Mn II, and Ni II.This work is supported by STFC(UK), The Leverhulme Trust, The Royal Society and NASA.References[1] Bergemann M, Pickering JC & Gehren T,“NLTE analysis of Co I/Co II lines in spectra of cool stars with new laboratory hyperfine splitting constants",MNRAS 401(2) 1334 (2010)[2] Thorne AP, Pickering JC & Semeniuk J,“The spectrum and term analysis of V II”, ApJS 207,13 (2013)[3] Thorne AP, Pickering JC & Semeniuk J,“The spectrum and term analysis of V I",ApJS 192,11 (2011)[4] Smillie DG

  5. Resonant electronic transport through a triple quantum-dot with Λ-type level structure under dual radiation fields

    SciTech Connect

    Guan, Chun; Xing, Yunhui; Zhang, Chao; Ma, Zhongshui

    2014-08-14

    Due to quantum interference, light can transmit through dense atomic media, a phenomenon known as electromagnetically induced transparency (EIT). We propose that EIT is not limited to light transmission and there is an electronic analog where resonant transparency in charge transport in an opaque structure can be induced by electromagnetic radiation. A triple-quantum-dots system with Λ-type level structure is generally opaque due to the level in the center dot being significantly higher and therefore hopping from the left dot to the center dot is almost forbidden. We demonstrate that an electromagnetically induced electron transparency (EIET) in charge of transport can indeed occur in the Λ-type system. The direct evidence of EIET is that an electron can travel from the left dot to the right dot, while the center dot apparently becomes invisible. We analyze EIET and the related shot noise in both the zero and strong Coulomb blockade regimes. It is found that the EIET (position, height, and symmetry) can be tuned by several controllable parameters of the radiation fields, such as the Rabi frequencies and detuning frequencies. The result offers a transparency/opaque tuning technique in charge transport using interfering radiation fields.

  6. Electro-optic and radiation damage performance of the CIS115, an imaging sensor for the JANUS optical camera onboard JUICE

    NASA Astrophysics Data System (ADS)

    Soman, M. R.; Allanwood, E. A. H.; Holland, A. D.; Stefanov, K.; Pratlong, J.; Leese, M.; Gow, J. P. D.; Smith, D. R.

    2016-08-01

    The Jupiter Icy Moon Explorer (JUICE) has been officially adopted as the next Large class mission by the European Space Agency, with a launch date of 2022. The science payload includes an optical camera, JANUS, which will perform imaging and mapping observations of Jupiter, its moons and icy rings. A 13 slot filter wheel will be used to provide spectral information in order for the JANUS experiment to study the geology and physical properties of Ganymede, Europa and Io, and to investigate processes and structures in the atmosphere of Jupiter. The sensor selected for JANUS is the back-thinned CIS115, a 3 MPixel CMOS Image Sensor from e2v technologies. The CIS115 has a 4-Transistor pixel design with a pinned photodiode to improve signal to noise performance by reducing dark current and allowing for reset level subtraction. The JUICE mission will consist of an 8 year cruise phase followed by a 3 year science phase in the Jovian system. Models of the radiation environment throughout the JUICE mission predict that the End of Life (EOL) non-ionising damage will be equivalent to 1010 protons cm-2 (10 MeV) and the EOL ionising dose will be 100 krad(Si), once the shielding from the spacecraft and instrument design is taken into account. An extensive radiation campaign is therefore being carried out to qualify and characterise the CIS115 for JANUS, as well as other space and terrestrial applications. Radiation testing to take the CIS115 to twice the ionising dose and displacement damage levels was completed in 2015 and the change in sensor performance has been characterised. Good sensor performance has been observed following irradiation and a summary of the key results from the campaign using gamma irradiation (ionising dose) will be presented here, including its soft X-ray detection capabilities, flat-band voltage shift and readout noise. In 2016, further radiation campaigns on flight-representative CIS115s will be undertaken and their results will be disseminated in

  7. Dust Propagation and Radiation In the Presence of a Low-level Jet in Central China on March 17, 2010

    NASA Astrophysics Data System (ADS)

    McDowell, B. K.; Chen, S. H.

    2014-12-01

    Suspended dust in the air can directly change the energy budget in the atmosphere and at the surface through scattering and absorption of radiation. Thus, dust can potentially modify the development of weather systems. To explore the dust-radiation effects on weather systems, a dust model was developed based on the Weather Research and Forecasting (WRF) model. The calculations of dust processes in the WRF dust model include emission, advection, boundary layer mixing, cumulus mixing, dust-radiation interaction, wet scavenging, and sedimentation. Due to a high vertical spatial resolution near the surface a time splitting method was applied to the calculation of dust sedimentation to relax the numerical time step. The "Hexi Corridor" is the historical name given to a string of oases along the northern slope of the Tibetan Plateau that formed a relatively easy transportation route between eastern China and central Asia. As trade developed over the centuries, this route became known as the Silk Road. This corridor also marks the transition from the relatively flat Gobi desert area in northern China to the elevated mountains of the Tibetan Plateau. These mountains present a southern barrier to the paths of dust storms that develop during spring outbreaks of the Mongolian Cyclone. In March of 2010, a series of dust storms developed in the Gobi Desert north of the Hexi Corridor that transported massive amounts of dust eastward to central and northeastern China, Korea and Japan. On March 17 during this event, a low-level jet developed along the northern perimeter of the Plateau, in alignment with upper level winds and the Hexi Corridor. Over the course of the day, a well-defined short-duration dust plume was emitted in the southern Gobi desert area and was transported over 1300 km in a southeast direction, over the Loess Plateau and into the Gansu Province. In this study, the interactions of synoptic conditions with regional topography that led to the development of the low-level

  8. Production of extended plasma channels in atmospheric air by amplitude-modulated UV radiation of GARPUN-MTW Ti : sapphire—KrF laser. Part 2. Accumulation of plasma electrons and electric discharge control

    NASA Astrophysics Data System (ADS)

    Zvorykin, V. D.; Ionin, Andrei A.; Levchenko, A. O.; Mesyats, Gennadii A.; Seleznev, L. V.; Sinitsyn, D. V.; Smetanin, Igor V.; Sunchugasheva, E. S.; Ustinovskii, N. N.; Shutov, A. V.

    2013-04-01

    The problem of the production of extended (~1 m) plasma channels is studied in atmospheric air by amplitude-modulated laser pulses of UV radiation, which are a superposition of a subpicosecond USP train amplified in a regenerative KrF amplifier with an unstable confocal resonator and a quasi-stationary lasing pulse. The USPs possess a high (0.2-0.3 TW) peak power and efficiently ionise oxygen molecules due to multiphoton ionisation, and the quasi-stationary lasing pulse, which has a relatively long duration (~100 ns), maintains the electron density at a level ne = (3-5) × 1014 cm—3 by suppressing electron attachment to oxygen. Experiments in laser triggering of high-voltage electric discharges suggest that the use of combined pulses results in a significant lowering of the breakdown threshold and enables controlling the discharge trajectory with a higher efficiency in comparison with smooth pulses. It was shown that controlled breakdowns may develop with a delay of tens of microseconds relative to the laser pulse, which is many orders of magnitude greater than the lifetime of free electrons in the laser-induced plasma. We propose a mechanism for this breakdown, which involves speeding-up of the avalanche ionisation of the air by negative molecular oxygen ions with a low electron binding energy (~0.5 eV) and a long lifetime (~1 ms), which are produced upon cessation of the laser pulse.

  9. An improved mathematical model for prediction of air quantity to minimise radiation levels in underground uranium mines.

    PubMed

    Panigrahi, Durga Charan; Sahu, Patitapaban; Mishra, Devi Prasad

    2015-02-01

    Ventilation is the primary means of controlling radon and its daughter concentrations in an underground uranium mine environment. Therefore, prediction of air quantity is the vital component for planning and designing of ventilation systems to minimise the radiation exposure of miners in underground uranium mines. This paper comprehensively describes the derivation and verification of an improved mathematical model for prediction of air quantity, based on the growth of radon daughters in terms of potential alpha energy concentration (PAEC), to reduce the radiation levels in uranium mines. The model also explains the prediction of air quantity depending upon the quality of intake air to the stopes. This model can be used to evaluate the contribution of different sources to radon concentration in mine atmosphere based on the measurements of radon emanation and exhalation. Moreover, a mathematical relationship has been established for quick prediction of air quantity to achieve the desired radon daughter concentration in the mines.

  10. Atomic squeezing in assembly of two two-level atoms interacting with a single mode coherent radiation

    NASA Astrophysics Data System (ADS)

    Prakash, H.; Kumar, R.

    2007-06-01

    Saito and Ueda [Phys. Rev. A 59, 3959 (1999)] studied atomic and radiation squeezing in interaction of a single mode coherent state left| α rightrangle of radiation with two excited two-level atoms, using the Jaynes Cummings Hamiltonian. They considered α real and studied squeezing of the Dicke operator Sx using the Kitagawa-Ueda criterion for squeezing and coupling times less than or nearly equal to \\vert α \\vert^{-1}. We obtain results to all orders in coupling time for atoms, which are initially in (i) fully excited, (ii) superradiant or in (iii) ground states and obtain more general results. We use our recently reported criterion for atomic squeezing, of which the Kitagawa-Ueda criterion is a special case, and obtain a much stronger (nearly 95%) atomic squeezing than that (nearly 1.1%) reported by Saito and Ueda.

  11. Shielding NSLS-II light source: Importance of geometry for calculating radiation levels from beam losses

    NASA Astrophysics Data System (ADS)

    Kramer, S. L.; Ghosh, V. J.; Breitfeller, M.; Wahl, W.

    2016-11-01

    Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produces significantly higher neutron component dose to the experimental floor than a lower energy beam injection and ramped operations. Minimizing this dose will require adequate knowledge of where the miss-steered beam can occur and sufficient EM shielding close to the loss point, in order to attenuate the energy of the particles in the EM shower below the neutron production threshold (<10 MeV), which will spread the incident energy on the bulk shield walls and thereby the dose penetrating the shield walls. Designing supplemental shielding near the loss point using the analytic shielding model is shown to be inadequate because of its lack of geometry specification for the EM shower process. To predict the dose rates outside the tunnel requires detailed description of the geometry and materials that the beam losses will encounter inside the tunnel. Modern radiation shielding Monte-Carlo codes, like FLUKA, can handle this geometric description of the radiation transport process in sufficient detail, allowing accurate predictions of the dose rates expected and the ability to show weaknesses in the design before a high radiation incident occurs. The effort required to adequately define the accelerator geometry for these codes has been greatly reduced with the implementation of the graphical interface of FLAIR to FLUKA. This made the effective shielding process for NSLS-II quite accurate and reliable. The principles used to provide supplemental

  12. Electron impact ionisation of encapsulated 99mTc@C 60 and 99mTc@C 70

    NASA Astrophysics Data System (ADS)

    Đustebek, J. B.; Đorđević, V. R.; Cvetićanin, J. M.; Veličković, S. R.; Veljković, M. V.; Nešković, O. M.; Rakočević, Z. L.; Bibić, N. M.

    2010-03-01

    The present study shows simultaneous surface ionisation and electron impact ionisation during the formation and investigation of endohedral fullerenes 99mTc@C 60 and 99mTc@C 70. The endohedral fullerenes were generated using a mass spectrometer with a triple rhenium filament as an ion source. The ionisation energies (IE) determined were: 8.52 ± 0.25 eV for 99mTc@C 60 and 9.57 ± 0.25 eV for 99mTc@ C 70.

  13. HELLE: Health Effects of Low Level Exposures/ Gezondheidseffecten van lage blootstellingniveaus [International workshop: Influence of low level exposures to chemicals and radiation on human and ecological health

    SciTech Connect

    Schoten, Eert

    1998-11-26

    The Health Council is closely involved in establishing the scientific foundation of exposure limits for substances and radiation in order to protect public health. Through the years, the Council has contributed to the formulation of principles and procedures, both for carcinogenic and for noncarcinogenic agents. As a rule, the discussion with regard to the derivation of health-based recommended exposure limits centers around the appropriateness of extrapolation methods (What can be inferred from data on high exposure levels and on experimental animals?). Generally speaking, there is a lack of direct information on the health effects of low levels of exposure. Effects at these levels cannot usually be detected by means of traditional animal experiments or epidemiological research. The capacity of these analytical instruments to distinguish between ''signal'' and ''noise'' is inadequate in most cases. Annex B of this report contains a brief outline of the difficulties and the established methods for tackling this problem. In spite of this, the hope exists that the posited weak signals, if they are indeed present, can be detected by other means. The search will have to take place on a deeper level. In other words, effort must be made to discover what occurs at underlying levels of biological organization when organisms are exposed to low doses of radiation or substances. Molecular and cell biology provide various methods and techniques which give an insight into the processes within the cell. This results in an increase in the knowledge about the molecular and cellular effects of exposure to agents, or stated differently, the working mechanisms which form the basis of the health effects. Last year, the Health Council considered that the time was ripe to take stock of the state of knowledge in this field. To this end, an international working conference was held from 19 to 21 October 1997, entitled ''Health Effects of Low Level Exposures: Scientific Developments and

  14. Synergistic effects of ethanol and UV radiation to reduce levels of selected foodborne pathogenic bacteria.

    PubMed

    Ha, Ji-Hyoung; Ha, Sang-Do

    2010-03-01

    The purpose of this study was to determine whether combined treatments would produce synergistic disinfection effects on food products during food processing compared with single treatments. We investigated the bactericidal effects of a commercial chemical disinfectant (ethanol) and of UV radiation on Bacillus cereus F4810/72, Cronobacter sakazakii KCTC 2949, Staphylococcus aureus ATCC 35556, Escherichia coli ATCC 10536, and Salmonella enterica Typhimurium NO/NA in vitro. Various concentrations of ethanol (10, 30, 40, and 50%) were tested with various exposure doses of UV radiation (6, 96, 216, 360, and 504 mWs/cm(2)) with a UV lamp. The combined ethanol-UV treatments resulted in greater reductions in bacterial counts than did either treatment alone. The synergistic effect values for B. cereus, C. sakazakii, S. aureus, S. enterica Typhimurium NO/NA, and E. coli were 0.40 to 1.52, 0.52 to 1.74, 0.20 to 2.32, 0.07 to 1.14, and 0.02 to 1.75 log CFU/ml, respectively. The results of this study suggest that a significant synergistic benefit results from combining ethanol and UV treatments against foodborne pathogens in vitro.

  15. Study of radiation induced deep-level defects in proton irradiated AlGaAs-GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Li, S. S.

    1980-01-01

    Radiation induced deep-level defects (both electron and hole traps) in proton irradiated AlGaAs-GaAs p-n junction solar cells are investigated along with the correlation between the measured defect parameters and the solar cell performance parameters. The range of proton energies studied was from 50 KeV to 10 MeV and the proton fluence was varied from 10 to the 10th power to 10 to the 13th power P/sq cm. Experimental tools employed include deep-level transient spectroscopy, capacitance-voltage, current voltage, and SEM-EBIC methods. Defect and recombination parameters such as defect density and energy level, capture cross section, carrier lifetimes and effective hole diffusion lengths in n-GaAs LPE layers were determined from these measurements.

  16. Ionizing radiation induced changes in phenotype, photosynthetic pigments and free polyamine levels in Vigna radiata (L.) Wilczek.

    PubMed

    Sengupta, Mandar; Chakraborty, Anindita; Raychaudhuri, Sarmistha Sen

    2013-05-01

    Effects of gamma rays on the free polyamine (PA) levels were studied in Vigna radiata (L.) Wilczek. Seeds exposed to different doses of gamma rays were checked for damage on phenotype, germination frequency and alteration in photosynthetic pigments. Free polyamine levels were estimated from seeds irradiated in dry and water imbibed conditions. Polyamine levels of seedlings grown from irradiated seeds, and irradiated seedlings from unexposed seeds were also measured. Damage caused by gamma irradiation resulted in decrease in final germination percentage and seedling height. Photosynthetic pigments decreased in a dose dependent manner as marker of stress. Polyamines decreased in irradiated dry seeds and in seedlings grown from irradiated seeds. Radiation stress induced increase in free polyamines was seen in irradiated imbibed seeds and irradiated seedlings. Response of polyamines towards gamma rays is dependent on the stage of the life cycle of the plant.

  17. Estimated association between dwelling soil contamination and internal radiation contamination levels after the 2011 Fukushima Daiichi nuclear accident in Japan

    PubMed Central

    Tsubokura, Masaharu; Nomura, Shuhei; Sakaihara, Kikugoro; Kato, Shigeaki; Leppold, Claire; Furutani, Tomoyuki; Morita, Tomohiro; Oikawa, Tomoyoshi; Kanazawa, Yukio

    2016-01-01

    Objectives Measurement of soil contamination levels has been considered a feasible method for dose estimation of internal radiation exposure following the Chernobyl disaster by means of aggregate transfer factors; however, it is still unclear whether the estimation of internal contamination based on soil contamination levels is universally valid or incident specific. Methods To address this issue, we evaluated relationships between in vivo and soil cesium-137 (Cs-137) contamination using data on internal contamination levels among Minamisoma (10–40 km north from the Fukushima Daiichi nuclear power plant), Fukushima residents 2–3 years following the disaster, and constructed three models for statistical analysis based on continuous and categorical (equal intervals and quantiles) soil contamination levels. Results A total of 7987 people with a mean age of 55.4 years underwent screening of in vivo Cs-137 whole-body counting. A statistically significant association was noted between internal and continuous Cs-137 soil contamination levels (model 1, p value <0.001), although the association was slight (relative risk (RR): 1.03 per 10 kBq/m2 increase in soil contamination). Analysis of categorical soil contamination levels showed statistical (but not clinical) significance only in relatively higher soil contamination levels (model 2: Cs-137 levels above 100 kBq/m2 compared to those <25 kBq/m2, RR=1.75, p value <0.01; model 3: levels above 63 kBq/m2 compared to those <11 kBq/m2, RR=1.45, p value <0.05). Conclusions Low levels of internal and soil contamination were not associated, and only loose/small associations were observed in areas with slightly higher levels of soil contamination in Fukushima, representing a clear difference from the strong associations found in post-disaster Chernobyl. These results indicate that soil contamination levels generally do not contribute to the internal contamination of residents in Fukushima; thus, individual

  18. A two-level atom and the problem of the radiation reaction in the semiclassical theory: optical Bloch equations revisited

    NASA Astrophysics Data System (ADS)

    Surdutovich, G. I.; Ghiner, A. V.

    2000-08-01

    A famous model of a two-level atom interacting with the classical electromagnetic field is used to illustrate the fundamental problem of the relationship between the dynamical and relaxation processes under the interaction of radiation with a quantum-mechanical system and, as a result, to derive nonlinear Bloch-like equations. The presented considerations are based on the analysis of the balance of the fluxes of energy between atomic and field subsystems. It is shown that the generally accepted model of the exponential relaxation deduced for an isolated excited atom and inserted customarily into optical Bloch equations (OBE) describing atom in an external field always leads to a very strange result: spontaneous emission of an atom should be accompanied by the radiation of the coherent field into the external field's mode. Making use of only the energetic considerations, we found the relaxation mechanism (in the form of additional terms in the OBE) which, on the one hand, guarantees the fulfillment of the energetic balance and, on the other hand, allows to introduce arbitrary additional collision-like relaxation mechanism without violation of this balance. Note that these additional terms introduced into OBE from the energetic considerations in a remarkable manner exactly correspond to the renormalization of the external field with the allowance of the classical radiation damping (RD) effect. The revisited OBE may be used as the starting point for considering the dynamics of an atom by making allowance for the quantum properties of an external field.

  19. Core level photoionization on free sub-10-nm nanoparticles using synchrotron radiation

    SciTech Connect

    Meinen, Jan; Leisner, Thomas; Khasminskaya, Svetlana; Eritt, Markus; Antonsson, Egill; Langer, Burkhard; Ruehl, Eckart

    2010-08-15

    A novel instrument is presented, which permits studies on singly charged free nanoparticles in the diameter range from 1 to 30 nm using synchrotron radiation in the soft x-ray regime. It consists of a high pressure nanoparticle source, a high efficiency nanoparticle beam inlet, and an electron time-of-flight spectrometer suitable for probing surface and bulk properties of free, levitated nanoparticles. We show results from x-ray photoelectron spectroscopy study near the Si L{sub 3,2}-edge on 8.2 nm SiO{sub 2} particles prepared in a nanoparticle beam. The possible use of this apparatus regarding chemical reactions on the surface of nanometer-sized particles is highlighted. This approach has the potential to be exploited for process studies on heterogeneous atmospheric chemistry.

  20. Image quality and radiation levels in videofluoroscopy for swallowing studies: A review

    SciTech Connect

    Beck, T.J.; Gayler, B.W. )

    1990-01-01

    Inexpensive video recording equipment coupled to conventional x-ray fluoroscopes is now in widespread use by clinicians for the evaluation of patients with swallowing disorders. The prevalence and simplicity of this apparatus have encouraged its use by clinical specialists who are often not specifically trained in the safe use of x-ray equipment, and this may not be in the best interest of either the patient or the examiner. This has prompted an overview of the operating principles of videofluorescopy equipment. The factors governing image quality are discussed as well as potential hazards and protective measures for both patients and operator. A method of estimating the radiation dose to sensitive tissues from a typical swallowing study is included. 6 references.

  1. A model for the formation of defects in RPC bakelite plates at high radiation levels

    NASA Astrophysics Data System (ADS)

    Greci, T.; Felli, F.; Saviano, G.; Benussi, L.; Bianco, S.; Passamonti, L.; Piccolo, D.; Pierluigi, D.; Russo, A.

    2013-04-01

    This study analyzes in detail the defects in bakelite observed in Resistive Plate Counters (RPC) after exposure to high-radiation environment and fluxed with humidified gas mixture at 9 kV voltage. Objective of this study was to identify the nature of defects and their formation mechanism. The defects were observed firstly on the whole RPC inner surface, and their localization mapped. The defected areas have been analyzed with optical and electron microscopy (SEM), and chemically by EDS (Energy Dispersion Spectroscopy) techniques. An area particularly defect-rich also analysed by x-ray diffraction (XRD). Samples of new and fluxed bakelite have been chemically analyzed by ICP-Plasma (via sample total digestion) in order to determine trace elements variations in composition. model is proposed to explain the chemistry of the formation process.

  2. Measurement of solar radiation at ground level in the region 1950-2150 A using ammonia actinometry

    NASA Technical Reports Server (NTRS)

    Knoot, P.; Reeves, R. R., Jr.

    1978-01-01

    The use of ammonia as an actinometer for measurement of the solar flux in the region 1950-2150 A is presented. The solar flux was found to be 270 million photons/sq cm per sec at ground level in this wavelength interval in an area with minimum overhead ozone concentration. The advantages of this method over previously used methods are discussed, and the results are related to the present estimates of the tropospheric photodissociation rates for the freons CFCl3 and CF2Cl2 by radiation in this wavelength region.

  3. Quality control methodology and implementation of X-radiation standards beams, mammography level, following the standard IEC 61267.

    PubMed

    Corrêa, E L; Vivolo, V; Potiens, M P A

    2012-07-01

    This study presents the results of the establishment of a quality control program developed and applied for the X-ray system of the Calibration Laboratory of IPEN. The X-ray standard beams, mammography level, using molybdenum and aluminum as additional filtration were established after the application of this quality control and the spectrometry of these qualities was made. The reference ionization chamber has traceability to the PTB. The radiation qualities RQR-M, RQA-M, RQN-M and RQB-M, following the recommendations of the IEC 61267 and the IAEA TRS 457 were established.

  4. Energy levels, Auger branching ratios, and radiative rates of the core-excited states of B-like carbon

    SciTech Connect

    Sun Yan; Gou Bingcong; Chen Feng

    2011-09-28

    Energy levels, Auger branching ratios, and radiative rates of the core-excited states of B-like carbon are calculated by the saddle-point variation and saddle-point complex-rotation methods. Relativistic and mass polarization corrections are included using first-order perturbation theory. Calculated Auger channel energies and branching ratios are used to identify high-resolution Auger spectrum in the 300-keV C{sup +}{yields} CH{sub 4} collision experiment. It is found that Auger decay of these five-electron core-excited states gives significant contributions to Auger spectrum in the range of 238-280 eV.

  5. Influence du traitement ionisant par rayonnement γ sur le pouvoir antioxydant de fractions polyphénoliques issues de substances d'origine végétale

    NASA Astrophysics Data System (ADS)

    Stuyck, S.; Connaulte, J.; Lesgards, G.; Prost, M.; Raffi, J.

    1998-04-01

    Ionizing radiation of vegetables is a cleaning up and preservation physical treatment which consists in submitting them to γ radiation, X radiation or electrons beam. This study deals with the influence of γ radiation on antioxidative effect of vegetables polyphenolic parts. In that purpose, we use a simple biological test based on erythrocytes haemolysis. Le traitement ionisant des produits végétaux est un procédé physique d'assainissement et de conservation qui consiste à les soumettre à l'action de rayonnements γ, de rayons X ou de faisceaux d'électrons. Ce travail porte sur l'étude de l'influence des rayonnements γ sur le pouvoir antioxydant de fractions polyphénoliques issues de substances d'origine végétale. Pour cela, un test biologique basé sur l'hémolyse d'érythrocytes est utilisé.

  6. Dose to level I and II axillary lymph nodes and lung by tangential field radiation in patients undergoing postmastectomy radiation with tissue expander reconstruction

    PubMed Central

    2011-01-01

    Background To define the dosimetric coverage of level I/II axillary volumes and the lung volume irradiated in postmastectomy radiotherapy (PMRT) following tissue expander placement. Methods and Materials Twenty-three patients were identified who had undergone postmastectomy radiotherapy with tangent only fields. All patients had pre-radiation tissue expander placement and expansion. Thirteen patients had bilateral expander reconstruction. The level I/II axillary volumes were contoured using the RTOG contouring atlas. The patient-specific variables of expander volume, superior-to-inferior location of expander, distance between expanders, expander angle and axillary volume were analyzed to determine their relationship to the axillary volume and lung volume dose. Results The mean coverage of the level I/II axillary volume by the 95% isodose line (VD95%) was 23.9% (range 0.3 - 65.4%). The mean Ipsilateral Lung VD50% was 8.8% (2.2-20.9). Ipsilateral and contralateral expander volume correlated to Axillary VD95% in patients with bilateral reconstruction (p = 0.01 and 0.006, respectively) but not those with ipsilateral only reconstruction (p = 0.60). Ipsilateral Lung VD50% correlated with angle of the expander from midline (p = 0.05). Conclusions In patients undergoing PMRT with tissue expanders, incidental doses delivered by tangents to the axilla, as defined by the RTOG contouring atlas, do not provide adequate coverage. The posterior-superior region of level I and II is the region most commonly underdosed. Axillary volume coverage increased with increasing expander volumes in patients with bilateral reconstruction. Lung dose increased with increasing expander angle from midline. This information should be considered both when placing expanders and when designing PMRT tangent only treatment plans by contouring and targeting the axilla volume when axillary treatment is indicated. PMID:22204504

  7. Cirrus cloud radiative forcing on surface-level shortwave and longwave irradiances at regional and global scale

    NASA Astrophysics Data System (ADS)

    Dupont, J. C.; Haeffelin, M.; Long, C. N.

    2009-04-01

    Cirrus clouds not only play a major role in the energy budget of the Earth-Atmosphere system, but are also important in the hydrological cycle. According to satellite passive remote sensing high-altitude clouds cover as much as 40% of the earth's surface on average and can reach 70% of cloud cover over the Tropics. Hence, given their very large cloud cover, the relatively small instantaneous radiative effects of these cirrus clouds can engender a significant cumulative radiative forcing at the surface. Precise calculations of the cirrus cloud radiative forcing are obtained from the difference between measured radiative fluxes downwelling at the surface in the presence of cirrus clouds (broadband flux measurements) and computed clear sky references (parametric models with RMS error < 5 W m-2). Overcast and clear sky period identification is obtained from a combined analysis of lidar and broadband flux measurements. In this study, we analyze two datasets: ground-based and satellite measurements. The firsts corresponds to solar and infrared irradiance measurements, cloud and aerosol Lidar backscattering profiles, microwave radiometer brightness temperatures, radiosonde profiles, and sun-photometer extinctions monitored at four observatories located in the midlatitudes (SIRTA Observatory and ARM SGP Lamont), the Tropics (ARM TWP Nauru) and the Arctic (ARM NSA Barrow). This dataset permits us to estimate the Cirrus cloud Radiative Forcing (cloud base altitude above 7 km) on surface-level shortwave (CRFSW) and longwave (CRFLW) irradiances. The sensitivity of CRFSW to Cloud Optical Thickness (noted CRFSW*) is established and ranges from 100 W m-2 to 200 W m-2 per unit of cloud optical thickness. The important variability of aerosols and water vapor content obtained in studying the 4 observatories allows us to quantify the combined influence of aerosol optical thickness and integrated water vapor on CRFSW* : 10 to 20 % CRFSW* range for turbid and pristine atmosphere

  8. Health physics manual of good practices for reducing radiation exposure to levels that are as low as reasonably achievable (ALARA)

    SciTech Connect

    Herrington, W.N.; Higby, D.P.; Kathren,., R.L.; Merwin, S.E.; Stoetzel, G.A.

    1988-06-01

    A primary objective of the US Department of Energy (DOE) health physics and radiation protection program has been to limit radiation exposures to those levels that are as low as reasonably achievable (ALARA). As a result, the ALARA concept developed into a program and a set of operational principles to ensure that the objective was consistently met. Implementation of these principles required that a guide be produced. The original ALARA guide was issued by DOE in 1980 to promote improved understanding of ALARA concepts within the DOE community and to assist those responsible for operational ALARA activities in attaining their goals. Since 1980, additional guidance has been published by national and international organizations to provide further definition and clarification to ALARA concepts. As basic ALARA experience increased, the value and role of the original guide prompted the DOE Office of Nuclear Safety (ONS) to support a current revision. The revised manual of good practices includes six sections: 1.0 Introduction, 2.0 Administration, 3.0 Optimization, 4.0 Setting and Evaluating ALARA Goals, 5.0 Radiological Design, and 6.0 Conduct of Operations. The manual is directed primarily to contractor and DOE staff who are responsible for conduct and overview of radiation protection and ALARA programs at DOE facilities. The intent is to provide sufficient guidance such that the manual, if followed, will ensure that radiation exposures are maintained as low as reasonably achievable and will establish the basis for a formally structured and auditable program. 118 refs., 16 figs., 3 tabs.

  9. Angular distribution of electrons in multiphoton ionisation of polarised Lithium atoms

    NASA Astrophysics Data System (ADS)

    Klimova, Yu. A.; Marmo, S. I.; Meremianin, A. V.

    2013-09-01

    The asymmetry of the angular distributions of photoelectrons in the photoionisation of polarised alkali atoms is investigated. The general formulas for the amplitude of the multiphoton ionisation of np-states are given. In these formulas the dynamical and kinematical factors are explicitly separated. Our calculations within Fues model potential approach demonstrate that, under the experimental conditions essentially similar to those employed in [M. Schuricke, Ganjun Zhu, J. Steinmann, K. Simeonidis, I. Ivanov, A. Kheifets, A.N. Grum-Grzhimailo, K. Bartschat, A. Dorn, J. Ullrich, Phys. Rev. A 83 (2011) 023413(11)], the relative magnitude of the linear magnetic dichroism in three-photon ionisation of Li can be as large as 30%.

  10. Exploring the Powerful Ionised Wind in the Seyfert Galaxy PG1211+143

    NASA Astrophysics Data System (ADS)

    Pounds, Ken

    2013-10-01

    Highly-ionised high-speed winds in AGN (UFOs) were first detected with XMM-Newton a decade ago, and are now established as a key factor in the study of SMBH accretion, and in the growth and metal enrichment of their host galaxies. However, information on the ionisation and dynamical structure, and the ultimate fate of UFOs remains very limited. We request a 600ks extended XMM-Newton study of the prototype UFO PG1211+143 in AO-13, to obtain high quality EPIC and RGS spectra, to map the flow structure and variability, while seeking evidence for the anticipated interaction with the ISM and possible conversion of the energetic wind to a momentum-driven flow.

  11. Experimental shielding evaluation of the radiation protection provided by the structurally significant components of residential structures.

    PubMed

    Dickson, E D; Hamby, D M

    2014-03-01

    The human health and environmental effects following a postulated accidental release of radioactive material to the environment have been a public and regulatory concern since the early development of nuclear technology. These postulated releases have been researched extensively to better understand the potential risks for accident mitigation and emergency planning purposes. The objective of this investigation is to provide an updated technical basis for contemporary building shielding factors for the US housing stock. Building shielding factors quantify the protection from ionising radiation provided by a certain building type. Much of the current data used to determine the quality of shielding around nuclear facilities and urban environments is based on simplistic point-kernel calculations for 1950s era suburbia and is no longer applicable to the densely populated urban environments realised today. To analyse a building's radiation shielding properties, the ideal approach would be to subject a variety of building types to various radioactive sources and measure the radiation levels in and around the building. While this is not entirely practicable, this research analyses the shielding effectiveness of ten structurally significant US housing-stock models (walls and roofs) important for shielding against ionising radiation. The experimental data are used to benchmark computational models to calculate the shielding effectiveness of various building configurations under investigation from two types of realistic environmental source terms. Various combinations of these ten shielding models can be used to develop full-scale computational housing-unit models for building shielding factor calculations representing 69.6 million housing units (61.3%) in the United States. Results produced in this investigation provide a comparison between theory and experiment behind building shielding factor methodology.

  12. Correlation of the ionisation response at selected points of IC sensitive regions with SEE sensitivity parameters under pulsed laser irradiation

    NASA Astrophysics Data System (ADS)

    Gordienko, A. V.; Mavritskii, O. B.; Egorov, A. N.; Pechenkin, A. A.; Savchenkov, D. V.

    2014-12-01

    The statistics of the ionisation response amplitude measured at selected points and their surroundings within sensitive regions of integrated circuits (ICs) under focused femtosecond laser irradiation is obtained for samples chosen from large batches of two types of ICs. A correlation between these data and the results of full-chip scanning is found for each type. The criteria for express validation of IC single-event effect (SEE) hardness based on ionisation response measurements at selected points are discussed.

  13. Exploring the effects of low-level laser therapy on fibroblasts and tumor cells following gamma radiation exposure.

    PubMed

    Ramos Silva, Camila; Cabral, Fernanda Viana; de Camargo, Claudinei Francisco Morais; Núñez, Silvia Cristina; Mateus Yoshimura, Tania; de Lima Luna, Arthur Cássio; Maria, Durvanei Augusto; Ribeiro, Martha Simões

    2016-12-01

    Ionizing radiation (IR) induces DNA damage and low-level laser therapy (LLLT) has been investigated to prevent or repair detrimental outcomes resulting from IR exposure. Few in vitro studies, however, explore the biological mechanisms underlying those LLLT benefits. Thus, in this work, fibroblasts and tumor cells are submitted to IR with doses of 2.5 Gy and 10 Gy. After twenty-four-h, the cells are exposed to LLLT with fluences of 30 J cm(-2) , 90 J cm(-2) , and 150 J cm(-2) . Cellular viability, cell cycle phases, cell proliferation index and senescence are evaluated on days 1 and 4 after LLLT irradiation. For fibroblasts, LLLT promotes - in a fluence-dependent manner - increments in cell viability and proliferation, while a reduction in the senescence was observed. Regarding tumor cells, no influences of LLLT on cell viability are noticed. Whereas LLLT enhances cell populations in S and G2 /M cell cycle phases for both cellular lines, a decrease in proliferation and increase in senescence was verified only for tumor cells. Putting together, the results suggest that fibroblasts and tumor cells present different responses to LLLT following exposure to gamma-radiation, and these promising results should stimulate further investigations. Senescence of tumor cells and fibroblasts on the 4(th) day after ionizing radiation (IR) and low-level laser therapy (LLLT) exposures. The number of senescent cells increased significantly for tumor cells (a) while for fibroblasts no increment was observed (b). The blue collor indicates senescence activity.

  14. Migration to new ampoule types for the NPL secondary standard ionisation chambers.

    PubMed

    Baker, M; Fenwick, A; Ferreira, K; Keightley, J; Johansson, L; Collins, S

    2014-05-01

    As the pre-calibrated sample containers used for activity assay in the two NPL secondary standards ionisation chambers are being phased out, suitable replacements have been identified. Characterisation checks have been carried out on the new ISO ampoules and a long-term recalibration schedule has been devised. Around 40 calibration factors have been determined so far and comparison of ion chamber responses for the two ampoule types showed variations of up to 7% for low energy photon emitting radionuclides.

  15. UV-B radiation increases anthocyanin levels in cotyledons and inhibits the growth of common buckwheat seedlings.

    PubMed

    Dębski, Henryk; Szwed, Magdalena; Wiczkowski, WiesŁaw; Szawara-Nowak, Dorota; Bączek, Natalia; Horbowicz, Marcin

    2016-12-01

    The impact of short-term UV-B treatment on the content of individual flavonoids and photosynthetic pigments in cotyledons and the growth of common buckwheat (Fagopyrum esculentum Moench) seedlings was investigated. Seeds of four common buckwheat cultivars were germinated in darkness over a period of 4 days and acclimatized for 2 days under a 16/8 h light/dark photoperiod at 24/18 °C day/night, and exposure to 100-120 μmol ∙ m(-2) ∙ s(-1) of photosynthetically active radiation (PAR). Seedlings were divided into three batches, including two batches subjected to different doses of UV-B (5 W ∙ m(-2) and 10 W ∙ m(-2), one hour per day) for 5 days, and a control group exposed to PAR only. Exposure to UV-B increased anthocyanin levels in the cotyledons of all examined cultivars, it inhibited hypocotyl elongation, but did not affect the content of photosynthetic pigments. Flavone concentrations increased in cv. Red Corolla and Kora, remained constant in cv. Panda and decreased in cv. Hruszowska. Exposure to UV-B decreased rutin levels in cv. Hruszowska, but not in the remaining cultivars. Cultivars Hruszowska, Panda and Kora appeared to be less resistant to UV-B than Red Corolla. Higher resistance to UV-B radiation in Red Corolla can probably be attributed to its higher content of anthocyanins and rutin in comparison with the remaining cultivars.

  16. Modest increase in temperature affects ODC activity in L929 cells: Low-level radiofrequency radiation does not.

    PubMed

    Höytö, A; Sihvonen, A-P; Alhonen, L; Juutilainen, J; Naarala, J

    2006-09-01

    The effects of low-level radiofrequency (RF) radiation and elevated temperature on ornithine decarboxylase (ODC) activity were investigated in murine L929 fibroblasts. The cells were exposed at 900 MHz either to a pulse-modulated (pulse frequency 217 Hz; GSM-type modulation) or a continuous wave signal at specific absorption rate (SAR) levels of 0.2 W kg(-1) (0.1-0.3 W kg(-1)) and 0.4 W kg(-1) (0.3-0.5 W kg(-1)) for 2, 8, or 24 h. RF radiation did not affect cellular ODC activity. However, a slight increase in temperature (0.8-0.9 degrees C) in the exposure system lead to decreased ODC activity in cell cultures. This was verified by tests in which cells were exposed to different temperatures in incubators. The results show that ODC activity is sensitive to small temperature differences in cell cultures. Hence, a precise temperature control in cellular ODC activity studies is needed.

  17. A Carbon Nano Tube electron impact ionisation source for low-power, compact spacecraft mass spectrometers

    NASA Astrophysics Data System (ADS)

    Sheridan, S.; Bardwell, M. W.; Morse, A. D.; Morgan, G. H.

    2012-04-01

    A novel ionisation source which uses commercially available Carbon Nano Tube devices is demonstrated as a replacement for a filament based ionisation source in an ion trap mass spectrometer. The carbon nanotube ion source electron emission was characterised and exhibited typical emission of 30 ± 1.7 μA with an applied voltage differential of 300 V between the carbon nanotube tips and the extraction grid. The ion source was tested for longevity and operated under a condition of continuous emission for a period of 44 h; there was an observed reduction in emission current of 26.5% during operation. Spectra were generated by installing the ion source into a Finnigan Mat ITD700 ion trap mass spectrometer; the spectra recorded showed all of the characteristic m/z peaks from m/z 69 to m/z 219. Perfluorotributylamine spectra were collected and averaged contiguously for a period of 48 h with no significant signal loss or peak mass allocation shift. The low power requirements and low mass of this novel ionisation source are considered be of great value to future space missions where mass spectrometric technology will be employed.

  18. Examining Pre-Service Teachers' Use of Atomic Models in Explaining Subsequent Ionisation Energy Values

    NASA Astrophysics Data System (ADS)

    Wheeldon, Ruth

    2012-06-01

    Chemistry students' explanations of ionisation energy phenomena often involve a number of non-scientific or inappropriate ideas being used to form causality arguments. Research has attributed this to many science teachers using these ideas themselves (Tan and Taber, in J Chem Educ 86(5):623-629, 2009). This research extends this work by considering which atomic models are used in pre-service teachers' explanations and how that relates to the causality ideas expressed. Thirty-one pre-service teachers were interviewed. Each was asked to describe and explain four different atomic representations (Rutherford, Electron cloud micrograph, Bohr and Schrödinger types) in as much detail as they could. They also provided an explanation for the subsequent ionisation energy values for an oxygen atom and identified which representations were helpful in explaining the values. Significantly, when pre-service teachers only used Bohr type representations, they did not use repelling electron ideas in their explanations. However, arguments that were based on electron-electron repulsion used features from Schrödinger type atoms. These findings suggest that many pre-service teachers need to develop their atomic modelling skills so that they select and use models more expertly and that subsequent ionisation explanations offer a context in which to explore different atomic models' limitations and their deployment as explanatory resources.

  19. The radiation characteristics of the transport packages with vitrified high-level waste

    SciTech Connect

    Bogatov, S. A.; Mitenkova, E. F. Novikov, N. V.

    2015-12-15

    The calculation method of neutron yield in the (α, n) reaction for a homogeneous material of arbitrary composition is represented. It is shown that the use of the ORIGEN 2 code excluding the real elemental composition of vitrified high-level waste leads to significant underestimation of the neutron yield in the (α, n) reaction. For vitrified high-level waste and spent nuclear fuel from VVER, the neutron fluxes are analyzed. The thickness of the protective materials for a transfer cask and a shipping cask with vitrified highlevel waste are estimated.

  20. The radiation characteristics of the transport packages with vitrified high-level waste

    NASA Astrophysics Data System (ADS)

    Bogatov, S. A.; Mitenkova, E. F.; Novikov, N. V.

    2015-12-01

    The calculation method of neutron yield in the (α, n) reaction for a homogeneous material of arbitrary composition is represented. It is shown that the use of the ORIGEN 2 code excluding the real elemental composition of vitrified high-level waste leads to significant underestimation of the neutron yield in the (α, n) reaction. For vitrified high-level waste and spent nuclear fuel from VVER, the neutron fluxes are analyzed. The thickness of the protective materials for a transfer cask and a shipping cask with vitrified highlevel waste are estimated.

  1. Radiation response of Chinese hamster cells after elevation of intracellular glutathione levels

    SciTech Connect

    Russo, A.; Mitchell, J.B.

    1984-08-01

    Cellular glutathione (GSH) levels were modulated by either inhibition of GSH synthesis by buthionine sulfoximine (BSO) or elevation of GSH by treatment with 2-oxo-thiazolidine-4-carboxylate (OTZ), cobaltous chloride, or cysteamine. Using these agents, x ray survival in air was assessed as a function of cellular GSH levels. Depletion of GSH by GSO resulted in slight sensitization of the aerated curve. However, elevation of GSH by as much as 200 to 300% of controls provided no radioprotection in air. These data are discussed in the context of the role of GSH and GSH peroxidase in the detoxification of peroxides produced by x rays.

  2. Cytokine levels as biomarkers of radiation fibrosis in patients treated with breast radiotherapy

    PubMed Central

    2014-01-01

    Background Radiation fibrosis is not easily measurable although clinical scores have been developed for this purpose. Biomarkers present an alternative more objective approach to quantification, and estimation in blood provides accessible samples. We investigated if blood cytokines could be used to measure established fibrosis in patients who have undergone radiotherapy for breast cancer. Methods We studied two cohorts treated by breast-conserving surgery and radiotherapy in the UK START Trial A, one with breast fibrosis (cases) and one with no or minimal fibrosis (controls). Two candidate cytokines, plasma connective tissue growth factor (CTGF) and serum interleukin-6 (IL6) were estimated by ELISA. Comparisons between cases and controls used the t-test or Mann–Whitney test and associations between blood concentration and clinical factors were assessed using the Spearman rank correlation coefficient. Results Seventy patients were included (26 cases, 44 controls). Mean time since radiotherapy was 9.9 years (range 8.3-12.0). No statistically significant differences between cases and controls in serum IL6 (median (IQR) 0.84 pg/ml (0.57-1.14), 0.75 pg/ml (0.41-1.43) respectively) or plasma CTGF (331.4 pg/ml (234.8-602.9), 334.5 pg/ml (270.0-452.8) were identified. There were no significant associations between blood cytokine concentration and age, fibrosis severity, breast size or time since radiotherapy. Conclusions No significant difference in IL6 or CTGF concentrations was detected between patients with breast fibrosis and controls with minimal or no fibrosis. PMID:24885397

  3. On the dependence of the two-level source function on its radiation field.

    NASA Technical Reports Server (NTRS)

    Steinitz, R.; Shine, R. A.

    1973-01-01

    The consequences of the universally made assumption that the stimulated emission profile is identical to the absorption profile are quantitatively investigated for a two-level atom with Doppler redistribution. The nonlinear terms arising in the source function are evaluated iteratively. We find that the magnitude of the effects is probably completely negligible for visible and UV solar lines.

  4. Effects of plasma microfields on radiative transitions from atomic levels above the ionization threshold

    NASA Technical Reports Server (NTRS)

    Davis, J.; Jacobs, V. L.

    1975-01-01

    The effects of plasma electric microfields on line-like optical features arising from atomic levels above the ionization threshold are investigated within the framework of the quasi-static and single-frequency dynamic-field theories of spectral-line broadening. The 2p(23)P to 1s2p(3)P and 2s2p(3)P to 1s2s(3)S transitions in helium and helium-like ions are treated as examples. The mixing of the doubly excited levels in the perturbing microfields produces Stark broadening of the emission lines and induces autoionization of the 2p(23)P level, which, unlike the 2s2p(3)P level, is metastable against autoionization in the field-free environment. Determination of the complete Stark-broadening profiles in thermal plasmas is complicated by the need to include the effects of both the (quasi-static) ion and the (dynamic) electron fields. Under nonequilibrium conditions, where electric fields from either electron or ion plasma waves can far exceed nearby particle fields, the calculation and interpretation of the line shapes may be simplified and could provide a diagnostic probe of the wave-field properties.

  5. [Mucosal tolerance and low level laser therapy: Is the delegation to radiation technicians possible?].

    PubMed

    Duchosal, S

    2015-10-01

    Mucositis remains a frequent complication of radiotherapy. Low level laser applications are used to accelerate the healing process. This technique is used routinely in our centre. It is performed by delegation by radiotherapists. The conditions of this delegation of tasks are addressed here.

  6. Energy levels and radiative data for Kr-like W38+ from MCDHF and RMBPT calculations

    NASA Astrophysics Data System (ADS)

    Guo, XueLing; Grumer, Jon; Brage, Tomas; Si, Ran; Chen, ChongYang; Jönsson, Per; Wang, Kai; Yan, Jun; Hutton, Roger; Zou, YaMing

    2016-07-01

    Energies, transition rates, line strengths and lifetimes have been computed for all levels of the 4p 6 and 4p 54d configurations of W38+ by using the multi-configuration Dirac-Hartree-Fock (MCDHF) method as well as relativistic many-body perturbation theory. We investigate systematically correlation, relativistic and quantum electro-dynamical (QED) effects of different properties, including excitation energies and transition rates. We demonstrate that it is important to include the core-valence correlation of rather deep subshells (including 3d and 3p) to reach close to spectroscopic accuracy for the transition energies. We also show that high-multipole transitions (E3, M2) are important for the lifetime of some metastable levels of 4p 54d ({}3{F}3,{}1{D}2,{}3{D}2). The present results are in good agreement with experiments and of considerably higher accuracy than those achieved in previous theoretical works.

  7. Ionisation from the 3s sub-level of highly charged ions

    NASA Technical Reports Server (NTRS)

    Golden, L. B.; Sampson, D. H.; Omidvar, K.

    1978-01-01

    Scaled electron-impact cross sections are calculated for ionization from the 3s sublevel of hydrogenic ions with Z equal infinity by use of the Born exchange or the Coulomb-Born Oppenheimer approximation (which is exact, apart from relativistic corrections, in this limit). The results are fitted to an analytic expression which goes into the correct Bethe approximation result at high energies and which can readily be integrated over a Maxwellian electron velocity distribution to obtain collision rates. These results permit calculation of the approximate cross section and collision rate for ionization from the 3s sublevel of any highly charged ion with Z/N larger than approximately 2. Results obtained by the described procedure for Fe-14(+) and Fe-15(+) are compared with results obtained by other procedures.

  8. Search for tachyons associated with extensive air showers in the ground level cosmic radiation

    NASA Technical Reports Server (NTRS)

    Masjed, H. F.; Ashton, F.

    1985-01-01

    Events detected in a shielded plastic scintillation counter occurring in the 26 microsec preceding the arrival of an extensive air shower at ground level with local electron density or = 20 m to the -2 power and the 240 microsec after its arrival have been studied. No significant excess of events (tachyons) arriving in the early time domain have been observed in a sample of 11,585 air shower triggers.

  9. The Influence of Chronic Exposure to Low Level Pulsed Microwave Radiation on Performance and Cognitive Behavior.

    DTIC Science & Technology

    1983-05-15

    response having defint .’e survival value for the animal (reinforced, low rate bar pressing) was markedly retarded, in comparison both with the...Foremost would be the need to handle a large number of animals in virtually identical fashion so that statistically adequate control and experimental...rat be irradiated independently, that is free of interaction with its neighbors, that the irradiation levels be stable for all animals in a group and

  10. Measurement of radiated electromagnetic field levels before and after a changeover to energy-efficient lighting.

    PubMed

    Kerr, L N; Boivin, W S; Boyd, S M; Coletta, J N

    2001-01-01

    An energy-efficient lighting retrofit at the Food and Drug Administration (FDA) Winchester Engineering and Analytical Center (WEAC) presented the opportunity to measure the electromagnetic (EM) environments in several rooms before and after changing the fluorescent lighting systems and to compare the changes in EM fields with the proposed standard EM immunity levels. Three rooms, representing the types of work areas in the laboratory, were selected and measured before and after the lighting changeover. Electric and magnetic field measurements were taken in the extremely low frequency (ELF), very low frequency (VLF), and radio frequency (RF) ranges of the EM spectrum. In 2 rooms, ELF electric fields were reduced and VLF and RF electric fields were increased as a result of the changeover to high-frequency fixtures. A third room received low-frequency, energy-efficient fixtures during this changeover, and this change resulted in only a slight increase of the ELF electric fields. The ELF magnetic fields were greatly reduced in 2 but only slightly reduced in the third room. No significant change was seen in VLF or RF magnetic fields for any of these rooms. Some field-strength measurements exceeded the proposed immunity levels recommended in the draft International Electrotechnical Commission standard IEC 60601-1-2 (rev. 2). The data show that increasing the separation distance from the fluorescent light fixtures greatly reduces the field-strength levels, limiting the potential for EM interference.

  11. The use of isodose levels to interpret radiation induced lung injury: a quantitative analysis of computed tomography changes

    PubMed Central

    Knoll, Miriam A.; Sheu, Ren Dih; Knoll, Abraham D.; Kerns, Sarah L.; Lo, Yeh-Chi; Rosenzweig, Kenneth E.

    2016-01-01

    Background Patients treated with stereotactic body radiation therapy (SBRT) for lung cancer are often found to have radiation-induced lung injury (RILI) surrounding the treated tumor. We investigated whether treatment isodose levels could predict RILI. Methods Thirty-seven lung lesions in 32 patients were treated with SBRT and received post-treatment follow up (FU) computed tomography (CT). Each CT was fused with the original simulation CT and treatment isodose levels were overlaid. The RILI surrounding the treated lesion was contoured. The RILI extension index [fibrosis extension index (FEI)] was defined as the volume of RILI extending outside a given isodose level relative to the total volume of RILI and was expressed as a percentage. Results Univariate analysis revealed that the planning target volume (PTV) was positively correlated with RILI volume at FU: correlation coefficient (CC) =0.628 and P<0.0001 at 1st FU; CE =0.401 and P=0.021 at 2nd FU; CE =0.265 and P=0.306 at 3rd FU. FEI −40 Gy at 1st FU was significantly positively correlated with FEI −40 Gy at subsequent FU’s (CC =0.689 and P=6.5×10−5 comparing 1st and 2nd FU; 0.901 and P=0.020 comparing 2nd and 3rd FU. Ninety-six percent of the RILI was found within the 20 Gy isodose line. Sixty-five percent of patients were found to have a decrease in RILI on the second 2nd CT. Conclusions We have shown that RILI evolves over time and 1st CT correlates well with subsequent CTs. Ninety-six percent of the RILI can be found to occur within the 20 Gy isodose lines, which may prove beneficial to radiologists attempting to distinguish recurrence vs. RILI. PMID:26981453

  12. Measurement of gamma radiation levels in soil samples from Thanjavur using γ-ray spectrometry and estimation of population exposure

    PubMed Central

    Senthilkumar, B.; Dhavamani, V.; Ramkumar, S.; Philominathan, P.

    2010-01-01

    This study assesses the level of terrestrial gamma radiation and associated dose rates from the naturally occurring radionuclides 232Th, 238U and 40K in 10 soil samples collected from Thanjavur (Tamil Nadu, India) using γ-ray spectrometry. The activity profile of radionuclides has clearly showed the existence of low level activity in Thanjavur. The geometric mean activity concentrations of 232Th, 238U and 40K is 42.9±9.4 Bq.kg−1, 14.7±1.7 Bq.kg−1 and 149.5±3.1 Bq.kg−1 respectively are derived from all the soil samples studied. The activity concentration of 232Th, 238U and 40K in soil is due to the presence of metamorphic rocks like shale, hornblende-biotite gneiss and quartzofeldspathic gneiss in these areas. Gamma absorbed dose rates in air outdoors were calculated to be in the range between 32 nGy.h−1 and 59.1 nGy.h−1 with an arithmetic mean of 43.3 ±9 nGy.h−1. This value is lesser than the population weighted world-averaged of 60 nGy.h−1. Inhabitants of Thanjavur are subjected to external gamma radiation exposure (effective dose) ranging between 39.2 and 72.6 μSv.y−1 with an arithmetic mean of 53.1±11 μSv.y−1. The values of the external hazard index determined from the soil radioactivity of the study area are less than the recommended safe levels. PMID:20177570

  13. Measurement of gamma radiation levels in soil samples from Thanjavur using gamma-ray spectrometry and estimation of population exposure.

    PubMed

    Senthilkumar, B; Dhavamani, V; Ramkumar, S; Philominathan, P

    2010-01-01

    This study assesses the level of terrestrial gamma radiation and associated dose rates from the naturally occurring radionuclides (232)Th, (238)U and (40)K in 10 soil samples collected from Thanjavur (Tamil Nadu, India) using gamma-ray spectrometry. The activity profile of radionuclides has clearly showed the existence of low level activity in Thanjavur. The geometric mean activity concentrations of (232)Th, (238)U and (40)K is 42.9+/-9.4 Bq.kg(-1), 14.7+/-1.7 Bq.kg(-1) and 149.5+/-3.1 Bq.kg(-1) respectively are derived from all the soil samples studied. The activity concentration of (232)Th, (238)U and (40)K in soil is due to the presence of metamorphic rocks like shale, hornblende-biotite gneiss and quartzofeldspathic gneiss in these areas. Gamma absorbed dose rates in air outdoors were calculated to be in the range between 32 nGy.h(-1) and 59.1 nGy.h(-1) with an arithmetic mean of 43.3 +/-9 nGy.h(-1). This value is lesser than the population weighted world-averaged of 60 nGy.h(-1). Inhabitants of Thanjavur are subjected to external gamma radiation exposure (effective dose) ranging between 39.2 and 72.6 muSv.y(-1) with an arithmetic mean of 53.1+/-11 muSv.y(-1). The values of the external hazard index determined from the soil radioactivity of the study area are less than the recommended safe levels.

  14. Neonatal exposure to a moderate dose of ionizing radiation causes behavioural defects and altered levels of tau protein in mice.

    PubMed

    Buratovic, Sonja; Stenerlöw, Bo; Fredriksson, Anders; Sundell-Bergman, Synnöve; Viberg, Henrik; Eriksson, Per

    2014-12-01

    Medical use of ionizing radiation (IR) has great benefits for treatment and diagnostic imaging, but procedures as computerized tomography (CT) may deliver a significant radiation dose to the patient. Recently, awareness has been raised about possible non-cancer consequences from low dose exposure to IR during critical phases of perinatal and/or neonatal brain development. In the present study neonatal NMRI mice were whole body irradiated with a single dose of gamma radiation (0; 350 and 500 mGy) on postnatal day 10 (PND 10). At 2 and 4 months of age, mice of both sexes were observed for spontaneous behaviour in a novel home environment. The neuroproteins CaMKII, GAP-43, synaptophysin and total tau in male mouse cerebral cortex and hippocampus were analysed 24h post-irradiation and in adults at 6 months of age exposed to 0 or 500 mGy on PND 10. A significantly dose-response related deranged spontaneous behaviour in 2- and 4-month-old mice was observed, where both males and females displayed a modified habituation, indicating reduced cognitive function. The dose of 350 mGy seems to be a tentative threshold. Six-month-old male mice showed a significantly increased level of total tau in cerebral cortex after irradiation to 500 mGy compared to controls. This demonstrates that a single moderate dose of IR, given during a defined critical period of brain development, is sufficient to cause persistently reduced cognitive function. Moreover, an elevation of tau protein was observed in male mice displaying reduced cognitive function.

  15. Ionizing radiations in pregnancy and teratogenesis: a review of literature.

    PubMed

    De Santis, M; Di Gianantonio, E; Straface, G; Cavaliere, A F; Caruso, A; Schiavon, F; Berletti, R; Clementi, M

    2005-01-01

    The present paper is a review of the data available in the literature concerning the prenatal exposure to radiation evaluating the reported teratogenic effect. We have particularly focused on the fetal effects of maternal ionising radiation exposure, both diagnostic and occupational, particularly in terms of congenital anomalies and birth weight. Ionising radiation represents a possible teratogen for the fetus, but this risk has been found to be dependent on the dosage and the effects correlatable to the gestational age at exposure. Recently, of particularly note is the fact that maternal thyroid exposure to diagnostic radiation has been associated with a slight reduction in the birth weight. Inadvertent exposure from diagnostic procedures in pregnancy doesn't usually increase the natural risk of congenital anomalies but creates a considerable state of maternal anxiety. Diagnostic radiological procedures should be avoided in pregnant women unless the information cannot be obtained by other techniques.

  16. Variable filtered photographic film as a radiation detector for environmental radiation monitoring

    NASA Astrophysics Data System (ADS)

    Majid, Zafri Azran Abdul; Junet, Laila Kalidah; Hazali, Norazlanshah; Abdullah, Abdul Adam; Hanafiah, Megat Ahmad Kamal Megat

    2013-05-01

    Environmental radiation is an ionising radiation that present in the natural environment which mostly originates from cosmic rays and radionuclide agents in the environment. This may lead the population to be exposed to the radiation. Therefore, the environmental radiation needs to be observed cautiously to minimize the impact of radiation. However, there is no specific or proper monitoring device that provides an outdoor environmental radiation monitoring. Hence, a new outdoor environmental radiation monitoring device was developed. A photographic film has been chosen as a dosimeter. The purpose of this study was to prove the covered photographic film attached with variable filter can be used to develop environmental radiation monitoring device to detect the ionising radiation. The filter used was variable thickness of plastic, aluminium (Al) and lead (Pb). The result from the study showed that the mean optical density (OD) values for medium speed film are in the range 0.41 to 0.73, and for fast speed film the OD values are in the range 0.51 to 1.35. The OD values decreased when the filter was attached. This has proven that the photographic film can be used to detect radiation and fast speed film was more sensitive compared to medium speed film.

  17. Secretory IgA, albumin level, and bone density as markers of biostimulatory effects of laser radiation

    NASA Astrophysics Data System (ADS)

    Kucerova, Hana; Dostalova, Tatjana; Himmlova, Lucia; Bartova, Jirina; Mazanek, Jiri

    1998-12-01

    The aim of contribution is to evaluate the effects of low- level laser radiation on healing process after human molars extraction in lower jaw using frequency 5 Hz, 292 Hz and 9000 Hz. Changes in bone density and monitoring of secretory IgA and albumin levels in saliva were used as a marker of biostimulatory effect. Bone density after extraction and 6 month after surgical treatment was examined using the dental digital radiography. Bone healing was followed by osseointegration of bone structure in extraction wound. Changes of bone density, secretory IgA and albumin levels were compared in groups of patients with laser therapy and control group without laser therapy. Differences in levels of the saliva markers (sIgA and albumin) were found to be significant comparing irradiated and non-irradiated groups, as well as comparing groups irradiated by various modulatory frequencies. Density of alveolar bone (histogram) was examined on five slices acquired from every RVG image. Histograms were evaluated with computer program for microscopic image analysis. Differences of density were verified in area of the whole slice. There were no significant differences found between the bone density in irradiated and non irradiated groups perhaps due to our used therapeutical diagram.

  18. Evidence of children's vulnerability to radiation in the context of radiological/nuclear events and considerations for emergency response.

    PubMed

    Lane, Rachel; Reinhardt, Pascale; Thompson, Patsy

    2010-11-01

    International organisations, such as International Atomic Energy Agency, United Nations Scientific Committee on the Effects of Atomic Radiation and World Health Organisation, together with committees of experts such as Biological Effects of Ionising Radiation and Committee on Medical Aspects of Radiation in the Environment, have assessed the effects of radiation on large exposed populations (Chernobyl accident, and Hiroshima/Nagasaki atomic bombings) and on nuclear energy workers and people living near nuclear facilities. Childhood and in utero exposure to moderate and high levels of ionizing radiation, such as those experienced during the atomic bombings of Japan, or from radiotherapy, is an established cause of leukaemia and solid cancer. There is no evidence of increase in solid cancers (excluding thyroid cancer) or leukaemia in the children from Chernobyl, and no evident link between worker's exposure to radiation and leukaemia in their offspring or with the presence of leukaemia clusters around nuclear power plants. It has also not been possible to demonstrate the evidence of radiation hereditary effects in human populations. In accordance with international guidance, Canadian Nuclear Safety Commission recommends optimisation of protection strategies to reduce doses to children. The development of credible radiological/nuclear event scenarios would assist in identifying probable sources of radioactivity and pathways of exposure for children. Such scenarios should then be used to identify protection strategies appropriate for children.

  19. EXPERIENCE MONITORING FOR LOW LEVEL NEUTRON RADIATION AT THE H-CANYON AT THE SAVANNAH RIVER SITE

    SciTech Connect

    HOGUE, MARK

    2005-10-07

    Department of Energy contractors are required to monitor external occupational radiation exposure of an individual likely to receive an effective dose equivalent to the whole body of 0.1 rem (0.001sievert) or more in a year. For a working year of 2000 hours, this translates to a dose rate of 0.05 mrem/hr (0.5 {micro}Sv/hr). This can be a challenging requirement for neutron exposure because traditional surveys with shielded BF{sub 3} proportional counters are difficult to conduct, particularly at low dose rates. A modified survey method was used at the Savannah River Site to find low dose rates in excess of 0.05 mrem/hr. An unshielded He{sup 3} detector was used to find elevated gross slow neutron counts. Areas with high count rates on the unshielded He{sup 3} detector were further investigated with shielded BF{sub 3} proportional counters and thermoluminescent neutron dosimeters were placed in the area of interest. An office area was investigated with this method. The data initially suggested that whole body neutron dose rates to office workers could be occurring at levels significantly higher than 0.1 rem (0.001sievert). The final evaluation, however, showed that the office workers were exposed to less than 0.1 rem/yr (0.001sievert/yr) of neutron radiation.

  20. Methods for assessing background levels of radiation and radioactive materials in the environment around uranium mills

    SciTech Connect

    Wogman, N.A.; Silker, W.B.; Glissmeyer, J.A.; Endres, G.W.R.

    1980-04-01

    Techniques and costs for determining background levels and mill contributions to the environment are assessed. Three specific programs are identified for the determination of natural background and mill contributions to that background. Since the most significant radiological impact to man within 10 km of mill tailings occurs through airborne /sup 222/Rn and its daughters, their measurement is emphasized in the suggested procedures. The next major radiological impact from the mills occurs through airborne movement of particulates from the mill and its tailings piles. Thus, the more sophisticated measurement technologies presented include measurements of airborne radionuclide particulates, as well as methods to measure the dose from /sup 222/Rn and its daughters. The most expensive methods for assessing background levels of radioactive materials around uranium mills allow a determination of uranium, thorium, and radium in water, soil, and vegetation, as well as air. The methodologies are organized by their increasing capital and operating costs. The more expensive techniques provide a better evaluation of the mill contribution to the environment. There is no single universal technique that is applicable to all mills.

  1. Studies of Background Levels for the NIF Yield Diagnostics from Neutron and Gamma Radiation

    SciTech Connect

    Song, P; Eder, D; Moran, M; Landen, O; O'Brien, D; Hsing, W

    2007-08-27

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is nearing completion of construction and is preparing for the National Ignition Campaign (NIC) with potentially significant yield in 2010. The design of a wide range of yield diagnostics in and outside the target-bay of the NIF must consider scattered background neutrons and neutron-induced gamma rays to measure neutrons and x-rays from target. The large and complex target chamber and facility make the calculation of scattered neutrons and gamma rays extremely challenging. The NIF was designed with shielded locations for many of the yield diagnostics including the neutron alcove and four diagnostic mezzanines. Accurate calculation of the background levels in these shielded locations requires advanced Monte Carlo techniques, e.g., variance reduction. Placement, size, and materials of collimators on the line of sight (LOS) through the shielding must be evaluated to trade off signal levels and unwanted backgrounds. The background at these locations is also affected by neutrons that pass through the laser beam tubes and scatter off of structures and walls in the switch yards. Detailed 3D Monte Carlo analyses are performed to determine neutron and gamma fluxes for some of the yield diagnostics.

  2. RH 1.5D: Polarized multi-level radiative transfer with partial frequency distribution

    NASA Astrophysics Data System (ADS)

    Pereira, Tiago M. D.; Uitenbroek, Han

    2015-02-01

    RH 1.5D performs Zeeman multi-level non-local thermodynamical equilibrium calculations with partial frequency redistribution for an arbitrary amount of chemical species. Derived from the RH code and written in C, it calculates spectra from 3D, 2D or 1D atmospheric models on a column-by-column basis (or 1.5D). It includes optimization features to speed up or improve convergence, which are particularly useful in dynamic models of chromospheres. While one should be aware of its limitations, the calculation of spectra using the 1.5D or column-by-column is a good approximation in many cases, and generally allows for faster convergence and more flexible methods of improving convergence. RH 1.5D scales well to at least tens of thousands of CPU cores.

  3. On the determination of radiative lifetimes of excited Mn I and Mn II levels

    NASA Astrophysics Data System (ADS)

    Schnabel, R.; Bard, A.; Kock, M.

    1995-12-01

    Time-resolved laser-induced fluorescence spectroscopy has been used to measure the lifetimes of 46 Mn I and 7 Mn II levels. A high-current hollow cathode produces an effusive beam of manganese atoms and ions in the ground states and in metastable states. Selected states are populated with tunable dye laser pulses. The following fluorescence is measured by means of a Tektronix 1 GHz transient digitizer. Including the separately measured response function of the system in the evaluation procedure the full decay curve can be applied for a determination of the lifetimes. All measurements are performed with linearly polarized laser beams adjusted to the magic angle in order to exclude systematic error sources. A comparison with literature data is given.

  4. Rise to modern levels of ocean oxygenation coincided with the Cambrian radiation of animals

    PubMed Central

    Chen, Xi; Ling, Hong-Fei; Vance, Derek; Shields-Zhou, Graham A.; Zhu, Maoyan; Poulton, Simon W.; Och, Lawrence M.; Jiang, Shao-Yong; Li, Da; Cremonese, Lorenzo; Archer, Corey

    2015-01-01

    The early diversification of animals (∼630 Ma), and their development into both motile and macroscopic forms (∼575–565 Ma), has been linked to stepwise increases in the oxygenation of Earth's surface environment. However, establishing such a linkage between oxygen and evolution for the later Cambrian ‘explosion' (540–520 Ma) of new, energy-sapping body plans and behaviours has proved more elusive. Here we present new molybdenum isotope data, which demonstrate that the areal extent of oxygenated bottom waters increased in step with the early Cambrian bioradiation of animals and eukaryotic phytoplankton. Modern-like oxygen levels characterized the ocean at ∼521 Ma for the first time in Earth history. This marks the first establishment of a key environmental factor in modern-like ecosystems, where animals benefit from, and also contribute to, the ‘homeostasis' of marine redox conditions. PMID:25980960

  5. Rise to modern levels of ocean oxygenation coincided with the Cambrian radiation of animals.

    PubMed

    Chen, Xi; Ling, Hong-Fei; Vance, Derek; Shields-Zhou, Graham A; Zhu, Maoyan; Poulton, Simon W; Och, Lawrence M; Jiang, Shao-Yong; Li, Da; Cremonese, Lorenzo; Archer, Corey

    2015-05-18

    The early diversification of animals (∼ 630 Ma), and their development into both motile and macroscopic forms (∼ 575-565 Ma), has been linked to stepwise increases in the oxygenation of Earth's surface environment. However, establishing such a linkage between oxygen and evolution for the later Cambrian 'explosion' (540-520 Ma) of new, energy-sapping body plans and behaviours has proved more elusive. Here we present new molybdenum isotope data, which demonstrate that the areal extent of oxygenated bottom waters increased in step with the early Cambrian bioradiation of animals and eukaryotic phytoplankton. Modern-like oxygen levels characterized the ocean at ∼ 521 Ma for the first time in Earth history. This marks the first establishment of a key environmental factor in modern-like ecosystems, where animals benefit from, and also contribute to, the 'homeostasis' of marine redox conditions.

  6. Low-level laser therapy in chemo- and radiation-induced mucositis: results of multicenter phase III studies

    NASA Astrophysics Data System (ADS)

    Bensadoun, Rene-Jean

    2001-04-01

    Low of middle energy irradiation with helium-neon laser (LLLT) appears to be a simple atraumatic technique for the prevention and treatment of mucositis of various origins. Preliminary findings obtained by Ciais et al prompted randomized multi-center, double-blind trials to evaluate LLLT for the prevention of a acute chemo- and radiation- induced stomatitis. Irradiation by LLLT corresponds to local application of a high photon density monochromatic light source. Activation of epithelial healing on LLL-treated surfaces, the most commonly recognized effect, has been confirmed by numerous in vitro studies, and is a function of cell type, wavelength, and energy dose. The mechanism of action at a molecular and enzymatic level is currently being studied (detoxification of free-radicals).

  7. A preliminary area survey of neutron radiation levels associated with the NASA variable energy cyclotron horizontal neutron delivery system

    NASA Technical Reports Server (NTRS)

    Roberts, W. K.; Leonard, R. F.

    1976-01-01

    The 25 MeV deuteron beam from the NASA variable energy cyclotron incident on a thick beryllium target will deliver a tissue neutron dose rate of 2.14 rad micron A-min at a source to skin distance of 125 cm. A neutron survey of the existing hallways with various shielding configurations made during operating of the horizontal neutron delivery system indicates that minimal amounts of additional neutron shielding material are required to provide a low level radiation environment within a self-contained neutron therapy control station. Measurements also indicate that the primary neutron distribution delivered by a planned vertical delivery system will be minimally perturbed by neutrons backscattered from the floor.

  8. Study of stillbirth and major congenital anomaly among newborns in the high-level natural radiation areas of Kerala, India.

    PubMed

    Jaikrishan, G; Sudheer, K R; Andrews, V J; Koya, P K M; Madhusoodhanan, M; Jagadeesan, C K; Seshadri, M

    2013-01-01

    Monitoring newborns for adverse outcomes like stillbirth and major congenital anomalies (MCA) is being carried out in government hospitals since 1995 in and around high-level natural radiation areas, a narrow strip of land on the southwest coast of Kerala, India. Natural deposits of monazite sand containing thorium and its daughter products account for elevated levels of natural radiation. Among 141,540 newborns [140,558 deliveries: 139,589 singleton, 957 twins (6.81 ‰), 11 triplets (0.078 ‰), and one quadruplet] screened, 615 (4.35 ‰) were stillbirth and MCA were seen in 1,370 (9.68 ‰) newborns. Clubfoot (404, 2.85 ‰) was the most frequent MCA followed by hypospadias (152, 2.10 ‰ among male newborns), congenital heart disease (168, 1.19 ‰), cleft lip/palate (149, 1.05 ‰), Down syndrome (104, 0.73 ‰), and neural tube defects (72, 0.51 ‰). Newborns with MCA among stillbirths were about 20-fold higher at 190.24 ‰ (117/615) compared to 8.89 ‰ (1,253/140,925) among live births (P < .001). Logistic regression was carried out to compare stillbirth, overall, and specific MCA among newborns from areas with dose levels of ≤1.5, 1.51-3.0, 3.01-6.0 and >6 mGy/year after controlling for maternal age at birth, gravida, consanguinity, ethnicity, and gender of the baby. Clubfoot showed higher prevalence of 3.26 ‰ at dose level of 1.51-3.0 mGy/year compared to 2.33 ‰ at ≤1.5 mGy/year (OR = 1.39; 95 % CI, 1.12-1.72), without indication of any clear dose-response. Prevalences of stillbirth, overall MCA, and other specific MCA were similar across different dose levels and were relatively lower than that reported elsewhere in India, probably due to better literacy, health awareness, and practices in the study population.

  9. Predictive value of tumor recurrence using urinary vascular endothelial factor levels in patients receiving radiation therapy for Glioblastoma Multiforme (GBM)

    PubMed Central

    2013-01-01

    Background Glioblastoma Multiforme (GBM) is the most common primary malignant tumor of the central nervous system. Standard of care includes maximal resection followed by chemoradiotherapy. Tumors need adequate perfusion and neovascularization to maintain oxygenation and for removal of wastes. Vascular endothelial growth factor (VEGF) is a well characterized pro-angiogenic factor. We hypothesized that the increases in urinary VEGF levels would occur early in the course of tumor recurrence or progression. We examine the feasibility of collecting and analyzing urinary VEGF levels in a prospective, multi-institutional trial (Radiation Therapy Oncology Group, RTOG, 0611) as well as the role of VEGF as a marker of tumor recurrence. Method We evaluated VEGF levels in urine specimens collected post-operatively, at the conclusion of radiation therapy (RT) and one month following RT. Urinary VEGF levels were correlated with tumor progression at one year. VEGF levels were measured by enzyme-linked immunosorbant assay in urine specimens and normalized to urinary creatinine levels. Sample size was determined based on a 50% 1-year recurrence rate. With a sensitivity and specificity of 80%, the expected 95% confidence interval was (0.69, 0.91) with 100 patients. A failure was defined as documented disease progression, recurrence or death before one year. Results 202 patients were enrolled between February-2006 and October-2007. Four patients were ineligible as they did not receive RT. Of the remaining 198 patients, 128 had all three samples collected. In this group, 35 patients (27.3%) did not progress, 89 (69.5%) had progression and 4 (3.1%) died without evidence of progression. Median VEGF levels at baseline were 52.9 pg/mg Cr (range 0.2- 15,034.4); on the last day of RT, 56.6 (range 0–2,377.1); and at one month follow-up, 70.0 (range 0.1-1813.2). In patients without progression at 1-year, both baseline VEGF level and end of RT VEGF level were lower than those of patients

  10. ESTIMATION OF CARDIAC CT ANGIOGRAPHY RADIATION DOSE TOWARD THE ESTABLISHMENT OF NATIONAL DIAGNOSTIC REFERENCE LEVEL FOR CCTA IN IRAN.

    PubMed

    Hosseini Nasab, Seyed Mohammad Bagher; Shabestani-Monfared, Ali; Deevband, Mohammad Reza; Paydar, Reza; Nabahati, Mehrdad

    2016-08-29

    In recent years, with the introduction of 64-slice CT and dual-source CT technology, coronary CT angiography (CCTA) has emerged as a useful diagnostic imaging modality as a non-invasive assessment of coronary heart disease. CT produces a larger radiation dose than other imaging tests and cardiac CT involves higher radiation dose with the advances in the spatial and temporal resolution. The aims of this study are patient dose assessment and establishment of national diagnostic reference level for CCTA in Iran. A questionnaire was sent to CCTA centers. Data for patient and CT protocols were obtained. The volumetric CT dose index (CTDIvol), dose length product (DLP) and total DLP were considered in the 32 cm standard body phantom. Calculation of estimated effective dose (ED) was obtained by multiplying the DLP by a conversion factor [k = 0.014 mSv (mGy·cm)(-1)]. Mean value of CTDIvol and DLP for CCTA was 50 mGy and 825 mGy·cm. The third quartile (75th) of the distribution of mean CTDIvol (66.54 mGy) and DLP (1073 mGy·cm) values was expressed as the diagnostic reference level (DRL) for CCTA in Iran. The median of ED was 10.26 mSv and interquartile range of ED was 7.08-15.03 mSv. A large variety in CTDIvol and DLP among CT scanner and different sites due to variability in CT parameter is noted. It seems that training could help to reduce patient's dose.

  11. Effects of UV-B radiation and water stress on gas exchange of soybeans under two different nitrogen levels

    SciTech Connect

    Rosa, L.M.; Forseth, I.N. )

    1993-06-01

    Due to anthropogenic destruction of stratospheric ozone, UV-B radiation is projected to increase in the near future. Other potential global climate changes in temperature and precipitation patterns raise the need for research into plant responses to multiple environmental stresses. The objective of this study was to document UV-B and water stress effects on gas exchange of soybean (Glycine max Merr.) under two nitrogen levels. Two soybean cultivars differing in sensitivity to UV-B were tested at fluence rates of 19.1 or 8.5 kJ m[sub [minus]2]day[sub [minus]1] (enhance and natural levels of UV-B, respectively). Measurements of photosaturated CO[sub 2] uptake at ambient CO[sub 2] (A). stomatal conductance. photosaturated O[sub 2] evolution at saturating CO[sub 2] (A[sub max]), long term water use efficiency (using [delta][sup 13]C), and nitrogen fixation (using [sup 15]N) were performed. No significant treatment effects on A could be detected. However A[sub max] was significantly increased, and stomatal conductance reduced (p<0.01) by increased UV-B at all levels of water and nitrogen for both cultivars, suggesting a stronger stomal limitation of photosynthesis under UV-B. Water and nitrogen use efficiency also decreased under increased UV-B in both cultivars (p<0.01).

  12. Low radiation level detection with room temperature InAs detector

    NASA Astrophysics Data System (ADS)

    Makai, Janos P.; Makai, Tamas

    2014-08-01

    Recently, room temperature or near room temperature InAs detectors are widely used in laser warning receivers, process control monitors, temperature sensors, etc. requiring linear operation over many decades of the sensitivity range. The linearity of zero biased Si, InGaAs and Ge detectors is thoroughly discussed in the literature, contrary to InAs detectors. In an earlier work of the authors it has been demonstrated that applying a bootstrap circuit to a Ge detector - depending on the frequency of the operation - will virtually increase the shunt resistance of the detector by 3-6 decades compared to the detector alone. In the present work, a similar circuitry was applied to a room temperature InAs detector, the differences between the bootstrapped Ge and bootstrapped InAs detector are underlined. It is shown, how the bootstrap circuit channels the photogenerated current to the feedback impedance decreasing with many decades the detectable low level limit of the detector - I/V converter unit. The linearity improvement results are discussed as a function of the chopping frequency, calculated and measured values are compared, the noise sources are analyzed and noise measurement results are presented.

  13. Simulation of ion induced radiation damage in cells

    NASA Astrophysics Data System (ADS)

    Friedland, W.; Jacob, P.; Paretzke, H. G.; Ottolenghi, A.; Ballarini, F.; Dingfelder, M.

    The biophysical simulation code PARTRAC has been used in several studies of DNA damage induced by various radiation qualities including photons electrons protons alphas and ions heavier than alpha particles Ion-electron interaction cross sections are taken from isotachic protons scaled by Z eff 2 with the effective charge calculated according to the Barkas formula Recently ion type dependent angular distributions were introduced for intermediate secondary electron energies taking into account the different kinematic scaling of the constituents of the electron spectra Calculated stopping powers radial dose distributions and secondary electron spectra were found in good agreement with available experimental and theoretical results Radiation damage to DNA is determined in PARTRAC by superposition of the calculated track structures with a DNA target model taking into account direct effects from coincidences of ionisations and atoms within the DNA helix as well as indirect effects due to interactions of OH radicals produced in water surrounding the DNA For a simulation of radiation effects in human cells this target model comprises several genomic structure levels from the DNA double-helix up to chromosomes Calculated DNA damage due to irradiation of human fibroblast cells by ions of boron nitrogen and neon was compared to corresponding experimental data The calculated total yield of DSB per dose showed saturation behaviour with an RBE of about 2 whereas experimental data had a decreasing tendency with increasing LET to RBE values

  14. Statins and Metformin Use Is Associated with Lower PSA Levels in Prostate Cancer Patients Presenting for Radiation Therapy

    PubMed Central

    Liu, Xiaonan; Li, Jing; Schild, Steven E.; Schild, Michael H.; Wong, William; Vora, Sujay; Herman, Michael G.; Fatyga, Mirek

    2017-01-01

    Background A possible association between the level of prostate specific antigen (PSA) and the use of some commonly prescribed medications has been reported in recent studies. Most of these studies were carried out in general populations of men who were screened for prostate cancer using the PSA test. We reported on the association between the initial PSA level and the use of statins, metformin and alpha-blockers in patients who were diagnosed with prostate cancer and presented for radiation therapy. Methods Three hundred and eighty one patients treated between the years of 2000-2005 and 2009-2012 were included in this retrospective study. The information about statin, metformin and alpha-blockers use was recorded immediately prior to treatment. Differences in PSA levels prior to treatment by medication status were estimated using univa-riate and multivariate linear regression on log PSA values. Results Compared with men who were not on these medications, the PSA level at presentation was 20% lower for statin users (p = 0.002) and 33% lower for metformin users (p = 0.004). We did not observe statistically significant associations between the use of statins or metformin and cancer stage, National Comprehensive Cancer Network (NCCN) risk score, or therapy outcome. A statistically significant association between the NCCN risk score and the use of alpha-blockers was observed (p = 0.002). Conclusions We found that statins and metformin were associated with lower PSA levels in prostate cancer patients to an extent that could influence management decisions. We found no statistically significant associations between the use of these medications and treatment outcomes. PMID:28239505

  15. Activation of VEGF and FGF induced angiogenesis under influence of low level laser radiation in vitro

    NASA Astrophysics Data System (ADS)

    Gasparyan, Levon; Brill, Grigory; Makela, Anu

    2006-02-01

    One of the feasible explanations for long-term treatment effects of laser therapy of diseases connected with tissue ischemia and altered blood circulation is activation of angiogenesis after low level laser irradiation. The aim of the current study was to investigate if laser irradiation can enhance vascular endothelial growth factor (VEGF) or basic fibroblast growth factor (FGF) induced angiogenesis in vitro. The study was conducted on rat thoracic aortal rings. Samples of group 1 served as control, samples of groups 2 and 3 were incubated with VEGF or FGF, group 4 samples were irradiated with laser (660 nm, 20 mW) during 10 min, samples of groups 5 and 6 were incubated with VEGF or FGF accordingly and received 10 min of laser irradiation. In the control group no noticeable angiogenesis occurred. The application of VEGF activated angiogenesis: the area covered by new vessels was 1,3+/-0,24 mm2 and the maximal length of vessels was 0,93+/-0,11 mm. Laser light irradiation (group 4) activated angiogenesis (1,9+/-0,29 mm2 and 0,75+/-0,10 mm). The combined influence of laser light and VEGF on angiogenesis (group 5) was significantly stronger (p <0,001), than each of the factors separately (6,98+/-0,88 mm2 and 1,7+/-0,23 mm). Application of FGF also activated angiogenesis: the area covered by new vessels was 2,76+/-0,22 mm2 and the maximal length of vessels was 1,19+/-0,12 mm. Combined influence of laser light and FGF on angiogenesis (group 6) was again significantly stronger (p <0,001), than each of the factors separately (5,43+/-0,28 mm2 and 1,99+/-0,10 mm). Studies show that laser irradiation can intensify effects of growth factors in vitro.

  16. Characterization of the deep levels responsible for non-radiative recombination in InGaN/GaN light-emitting diodes

    SciTech Connect

    Meneghini, M. La Grassa, M.; Vaccari, S.; Meneghesso, G.; Zanoni, E.

    2014-03-17

    This paper presents an extensive investigation of the deep levels related to non-radiative recombination in InGaN/GaN light-emitting diodes (LEDs). The study is based on combined optical and deep-level transient spectroscopy measurements, carried out on LEDs with identical structure and with different values of the non-radiative recombination coefficient. Experimental data lead to the following, relevant, results: (i) LEDs with a high non-radiative recombination coefficient have a higher concentration of a trap (labeled as “e{sub 2}”) with an activation energy of 0.7 eV, which is supposed to be located close to/within the active region; (ii) measurements carried out with varying filling pulse duration suggest that this deep level behaves as a point-defect/dislocation complex. The Arrhenius plot of this deep level is critically compared with the previous literature reports, to identify its physical origin.

  17. Headspace analysis of new psychoactive substances using a Selective Reagent Ionisation-Time of Flight-Mass Spectrometer

    PubMed Central

    Acton, W. Joe; Lanza, Matteo; Agarwal, Bishu; Jürschik, Simone; Sulzer, Philipp; Breiev, Kostiantyn; Jordan, Alfons; Hartungen, Eugen; Hanel, Gernot; Märk, Lukas; Mayhew, Chris A.; Märk, Tilmann D.

    2014-01-01

    The rapid expansion in the number and use of new psychoactive substances presents a significant analytical challenge because highly sensitive instrumentation capable of detecting a broad range of chemical compounds in real-time with a low rate of false positives is required. A Selective Reagent Ionisation-Time of Flight-Mass Spectrometry (SRI-ToF-MS) instrument is capable of meeting all of these requirements. With its high mass resolution (up to m/Δm of 8000), the application of variations in reduced electric field strength (E/N) and use of different reagent ions, the ambiguity of a nominal (monoisotopic) m/z is reduced and hence the identification of chemicals in a complex chemical environment with a high level of confidence is enabled. In this study we report the use of a SRI-ToF-MS instrument to investigate the reactions of H3O+, O2+, NO+ and Kr+ with 10 readily available (at the time of purchase) new psychoactive substances, namely 4-fluoroamphetamine, methiopropamine, ethcathinone, 4-methylethcathinone, N-ethylbuphedrone, ethylphenidate, 5-MeO-DALT, dimethocaine, 5-(2-aminopropyl)benzofuran and nitracaine. In particular, the dependence of product ion branching ratios on the reduced electric field strength for all reagent ions was investigated and is reported here. The results reported represent a significant amount of new data which will be of use for the development of drug detection techniques suitable for real world scenarios. PMID:25844048

  18. Radiation-induced bystander effects: are they good, bad or both?

    PubMed

    Mothersill, Carmel; Seymour, Colin

    2005-01-01

    Our current knowledge of the mechanisms underlying the induction of bystander effects by low dose-low linear-energy-transfer ionising radiation is reviewed, and the question of how bystander effects may be related to observed adaptive responses, systemic genomic instability or other effects of low doses exposures is considered. Bystander effects appear to be the result of a generalised stress response in tissues or cells. The signals may be produced by all exposed cells but the response may require a quoram in order to be expressed. The major response involving low LET radiation exposure discussed in the existing literature is a death response, which has many characteristics of apoptosis but may be detected in cell lines without p53 expression. While a death response might appear to be adverse, it can in fact be protective and remove damaged cells from the population. Since many cell populations carry damaged cells without being exposed to radiation ('background damage') low doses exposures might cause removal of cells damaged by agents other than the test dose of radiation, which would lead to the production of 'u- or n-shaped' dose-response curves. The level of harmful or beneficial response would then be related to the background damage carried by the cell population and the genetic programme determining response to damage. This model may be important when attempting to predict the consequences of mixed exposures involving radiation and other environmental stressors.

  19. KINETIC SIMULATIONS OF THERMOLUMINESCENCE DOSE RESPONSE: LONG OVERDUE CONFRONTATION WITH THE EFFECTS OF IONISATION DENSITY.

    PubMed

    Horowitz, Y S; Eliyahu, I; Oster, L

    2016-12-01

    The reader will time-travel through almost seven decades of kinetic models and mathematical simulations of thermoluminescence (TL) characteristics based on the band-gap theory of the solid state. From post-World-War II, ideas concerning electron trapping mechanisms to the highly idealised one trap-one recombination (OTOR) model first elaborated in 1956 but still in 'high gear' today. The review caresses but purposely avoids in-depth discussion of the endless stream of papers discussing the intricacies of glow peak shapes arising from first-order, second-order, mixed-order and general-order kinetics predominantly based on non-interacting systems, and then on to the more physically realistic scenarios that have attempted to analyse complex systems involving ever greater numbers of interacting trapping centres, luminescent centres and non-luminescent centres. The review emphasises the difficulty the band-gap models have in the simulation of dose response linear/supralinear behaviour and especially the dependence of the supralinearity on ionisation density. The significance of the non-observation of filling-rate supralinearity in the absorption stage is emphasised since it removes from consideration the possibility of TL supralinearity arising from irradiation stage supralinearity. The importance of the simultaneous action of both localised and delocalised transitions has gradually penetrated the mindset of the community of kinetic researchers, but most simulations have concentrated on the shape of glow peaks and the extraction of the glow peak parameters, E (the thermal activation energy) and s (the attempt-to-escape frequency). The simulation of linear/supralinear dose response and its dependence on ionisation density have been largely avoided until recently due to the fundamental schism between the effects of ionisation density and some basic assumptions of the band-gap model. The review finishes with an in-depth presentation and discussion of the most recent

  20. Monte Carlo configuration interaction applied to multipole moments, ionisation energies and electron affinities.

    PubMed

    Coe, Jeremy P; Taylor, Daniel J; Paterson, Martin J

    2013-05-15

    The method of Monte Carlo configuration interaction (MCCI) (Greer, J. Chem. Phys. 1995a, 103, 1821; Tong, Nolan, Cheng, and Greer, Comp. Phys. Comm. 2000, 142, 132) is applied to the calculation of multipole moments. We look at the ground and excited state dipole moments in carbon monoxide. We then consider the dipole of NO, the quadrupole of N2 and of BH. An octupole of methane is also calculated. We consider experimental geometries and also stretched bonds. We show that these nonvariational quantities may be found to relatively good accuracy when compared with full configuration interaction results, yet using only a small fraction of the full configuration interaction space. MCCI results in the aug-cc-pVDZ basis are seen to generally have reasonably good agreement with experiment. We also investigate the performance of MCCI when applied to ionisation energies and electron affinities of atoms in an aug-cc-pVQZ basis. We compare the MCCI results with full configuration interaction quantum Monte Carlo (Booth and Alavi, J. Chem. Phys. 2010, 132, 174104; Cleland, Booth, and Alavi, J. Chem. Phys. 2011, 134, 024112) and "exact" nonrelativistic results (Booth and Alavi, J. Chem. Phys. 2010, 132, 174104; Cleland, Booth, and Alavi, J. Chem. Phys. 2011, 134, 024112). We show that MCCI could be a useful alternative for the calculation of atomic ionisation energies however electron affinities appear much more challenging for MCCI. Due to the small magnitude of the electron affinities their percentage errors can be high, but with regards to absolute errors MCCI performs similarly for ionisation energies and electron affinities.

  1. Impact of Ultrahigh Baseline PSA Levels on Biochemical and Clinical Outcomes in Two Radiation Therapy Oncology Group Prostate Clinical Trials

    SciTech Connect

    Rodrigues, George; Bae, Kyounghwa; Roach, Mack; Lawton, Colleen; Donnelly, Bryan; Grignon, David; Hanks, Gerald; Porter, Arthur; Lepor, Herbert; Sandler, Howard

    2011-06-01

    Purpose: To assess ultrahigh (UH; prostate-specific antigen [PSA]levels {>=}50 ng/ml) patient outcomes by comparison to other high-risk patient outcomes and to identify outcome predictors. Methods and Materials: Prostate cancer patients (PCP) from two Phase III Radiation Therapy Oncology Group clinical trials (studies 9202 and 9413) were divided into two groups: high-risk patients with and without UH baseline PSA levels. Predictive variables included age, Gleason score, clinical T stage, Karnofsky performance score, and treatment arm. Outcomes included overall survival (OS), distant metastasis (DM), and biochemical failure (BF). Unadjusted and adjusted hazard ratios (HRs) were calculated using either the Cox or Fine and Gray's regression model with associated 95% confidence intervals (CI) and p values. Results: There were 401 patients in the UH PSA group and 1,792 patients in the non-UH PSA PCP group of a total of 2,193 high-risk PCP. PCP with UH PSA were found to have inferior OS (HR, 1.19; 95% CI, 1.02-1.39, p = 0.02), DM (HR, 1.51; 95% CI, 1.19-1.92; p = 0.0006), and BF (HR, 1.50; 95% CI, 1.29-1.73; p < 0.0001) compared to other high-risk PCP. In the UH cohort, PSA level was found to be a significant factor for the risk of DM (HR, 1.01; 95% CI, 1.001-1.02) but not OS and BF. Gleason grades of 8 to 10 were found to consistently predict for poor OS, DM, and BF outcomes (with HR estimates ranging from 1.41-2.36) in both the high-risk cohort and the UH cohort multivariable analyses. Conclusions: UH PSA levels at diagnosis are related to detrimental changes in OS, DM, and BF. All three outcomes can be modeled by various combinations of all predictive variables tested.

  2. Forensic applications of desorption electrospray ionisation mass spectrometry (DESI-MS).

    PubMed

    Morelato, Marie; Beavis, Alison; Kirkbride, Paul; Roux, Claude

    2013-03-10

    Desorption electrospray ionisation mass spectrometry (DESI-MS) is an emerging analytical technique that enables in situ mass spectrometric analysis of specimens under ambient conditions. It has been successfully applied to a large range of forensically relevant materials. This review assesses and highlights forensic applications of DESI-MS including the analysis and detection of illicit drugs, explosives, chemical warfare agents, inks and documents, fingermarks, gunshot residues and drugs of abuse in urine and plasma specimens. The minimal specimen preparation required for analysis and the sensitivity of detection achieved offer great advantages, especially in the field of forensic science.

  3. The WISSH quasars project. I. Powerful ionised outflows in hyper-luminous quasars

    NASA Astrophysics Data System (ADS)

    Bischetti, M.; Piconcelli, E.; Vietri, G.; Bongiorno, A.; Fiore, F.; Sani, E.; Marconi, A.; Duras, F.; Zappacosta, L.; Brusa, M.; Comastri, A.; Cresci, G.; Feruglio, C.; Giallongo, E.; La Franca, F.; Mainieri, V.; Mannucci, F.; Martocchia, S.; Ricci, F.; Schneider, R.; Testa, V.; Vignali, C.

    2017-02-01

    Models and observations suggest that both the power and effects of AGN feedback should be maximised in hyper-luminous (LBol > 1047 erg s-1) quasars, i.e. objects at the brightest end of the AGN luminosity function. In this paper, we present the first results of a multiwavelength observing programme, focusing on a sample of WISE/SDSS selected hyper-luminous (WISSH) broad-line quasars at z ≈ 1.5-5. The WISSH quasars project has been designed to reveal the most energetic AGN-driven outflows, estimate their occurrence at the peak of quasar activity, and extend the study of correlations between outflows and nuclear properties up to poorly investigated, extreme AGN luminosities, i.e. LBol 1047 - 1048 erg s-1. We present near-infrared, long-slit LBT/LUCI1 spectroscopy of five WISSH quasars at z ≈ 2.3 - 3.5, showing prominent [OIII] emission lines with broad (FWHM 1200-2200 km s-1) and skewed profiles. The luminosities of these broad [OIII] wings are the highest measured so far, with L[OIII]broad ≳ 5 × 1044 erg s-1, and reveal the presence of powerful ionised outflows with associated mass outflow rates Ṁ ≳ 1700M⊙ yr-1 and kinetic powers Ėkin ≳ 1045 erg s-1. Although these estimates are affected by large uncertainties because of the use of [OIII] as a tracer of ionised outflows and the very basic outflow model adopted here, these results suggest that in our hyper-luminous targets the AGN is highly efficient at pushing large amounts of ionised gas outwards. Furthermore, the mechanical outflow luminosities measured for WISSH quasars correspond to higher percentages ( 1-3%) of LBol than those derived for AGN with lower LBol. Our targets host very massive (MBH ≳ 2 × 109M⊙) black holes that are still accreting at a high rate (i.e. a factor of 0.4-3 of the Eddington limit). These findings clearly demonstrate that WISSH quasars offer the opportunity to probe the extreme end of both luminosity and supermassive black holes (SMBH) mass functions and revealing

  4. Characterisation of the muon beams for the Muon Ionisation Cooling Experiment

    SciTech Connect

    Adams, D.; et al.,

    2013-10-01

    A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.5--2.3 \\pi mm-rad horizontally and 0.6--1.0 \\pi mm-rad vertically, a horizontal dispersion of 90--190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE.

  5. Multi-level synchrotron radiation-based microtomography of the dental alveolus and its consequences for orthodontics.

    PubMed

    Dalstra, M; Cattaneo, P M; Laursen, M G; Beckmann, F; Melsen, B

    2015-03-18

    Multilevel synchrotron radiation-based microtomography has been performed on a human jaw segment obtained at autopsy by cutting increasingly smaller samples from the original segment. The focus of this study lay on the microstructure of the interface between root, periodontal ligament (PDL) and alveolar bone in order to find an answer to the question why alveolar bone remodels during orthodontic loading, when the associated stress and strain levels calculated with finite element analyses are well below the established threshold levels for bone remodeling. While the inner surface of the alveolus appears to be rather smooth on the lower resolution scans, detailed scans of the root-PDL-bone interface reveal that on a microscopical scale it is actually quite rough and uneven with bony spiculae protruding into the PDL space. Any external (orthodontic) loading applied to the root, when transferred through the PDL to the alveolar bone, will cause stress concentrations in these spiculae, rather than be distributed over a "smooth surface". As osteocyte lacunae are shown to be present in these spiculae, the local amplified stresses and strain can well be registered by the mechano-sensory network of osteocytes. In addition, a second stress amplification mechanism, due to the very presence of the lacunae themselves, is evidence that stresses and strains calculated with FE analyses, based on macroscopical scale models of teeth and their supporting structures, grossly underestimate the actual mechanical loading of alveolar bone at tissue level. It is therefore hypothesized that remodeling of alveolar bone is subject to the same biological regulatory process as remodeling in other bones.

  6. Using photo-ionisation models to derive carbon and oxygen gas-phase abundances in the rest UV

    NASA Astrophysics Data System (ADS)

    Pérez-Montero, Enrique; Amorín, Ricardo

    2017-01-01

    We present a new method to derive oxygen and carbon abundances using the ultraviolet (UV) lines emitted by the gas-phase ionised by massive stars. The method is based on the comparison of the nebular emission-line ratios with those predicted by a large grid of photo-ionisation models. Given the large dispersion in the O/H - C/O plane, our method firstly fixes C/O using ratios of appropriate emission lines and, in a second step, calculates O/H and the ionisation parameter from carbon lines in the UV. We find abundances totally consistent with those provided by the direct method when we apply this method to a sample of objects with an empirical determination of the electron temperature using optical emission lines. The proposed methodology appears as a powerful tool for systematic studies of nebular abundances in star-forming galaxies at high redshift.

  7. Analysis of the effects of increasing doses of ionizing radiation to the exteriorized rat ovary on follicular development, atresia, and serum gonadotropin levels

    SciTech Connect

    Jarrell, J.; YoungLai, E.V.; Barr, R.; O'Connell, G.; Belbeck, L.; McMahon, A.

    1986-02-01

    There is increasing interest in the effects of environmental and therapeutic agents on the reproductive system, in particular, the ovary. To study the effects of controlled doses of ionizing radiation to the ovary, Sprague-Dawley rats had their ovaries exteriorized and subjected to increasing doses of radiation. There was a significant increase in ovarian follicular atresia, a significant increase in serum follicle-stimulating hormone levels, but no change in serum luteinizing hormone levels. This experimental protocol may facilitate the testing putative radioprotectants.

  8. Measuring technique for thermal ionisation mass spectrometry of human tracer kinetic study with stable cerium isotopes.

    PubMed

    Keiser, Teresa; Höllriegl, Vera; Giussani, Augusto; Oeh, Uwe

    2011-06-01

    Thermal ionisation mass spectrometry (TIMS) method has been developed for the simultaneous detection of different cerium isotopes in biological samples (i.e., blood and urine) at very low concentrations. The work has been done in the frame of a biokinetic study, where different stable cerium isotopes have been administered orally and intravenously as tracers to the human body. In order to develop an appropriate detection method for the tracers in the biological samples, an optimum sample preparation technique has been set and adapted to the specific requirements of the analysis technique used, i.e., TIMS. For sample evaporation and ionisation, the double tantalum filament technique showed the best results. The ions produced were simultaneously collected on a secondary electron multiplier so that the isotopic ratios of the cerium isotopes in the biological samples could be measured. The technique has been optimised for the determination of cerium down to 1 ng loaded on the evaporation filament corresponding to cerium concentrations of down to 1 ng ml(-1) in the blood or urine samples. It has been shown that the technique is reliable in application and enables studies on cerium metabolism and biokinetics in humans without employing radioactive tracers.

  9. An experimental and theoretical study of core-valence double ionisation of acetaldehyde (ethanal).

    PubMed

    Zagorodskikh, S; Vapa, M; Vahtras, O; Zhaunerchyk, V; Mucke, M; Eland, J H D; Squibb, R J; Linusson, P; Jänkälä, K; Ågren, H; Feifel, R

    2016-01-28

    Core-valence double ionisation spectra of acetaldehyde (ethanal) are presented at photon energies above the carbon and oxygen 1s ionisation edges, measured by a versatile multi-electron coincidence spectroscopy technique. We use this molecule as a testbed for analyzing core-valence spectra by means of quantum chemical calculations of transition energies. These theoretical approaches range from two simple models, one based on orbital energies corrected by core valence interaction and one based on the equivalent core approximation, to a systematic series of quantum chemical electronic structure methods of increasing sophistication. The two simple models are found to provide a fast orbital interpretation of the spectra, in particular in the low energy parts, while the coverage of the full spectrum is best fulfilled by correlated models. CASPT2 is the most sophisticated model applied, but considering precision as well as computational costs, the single and double excitation configuration interaction model seems to provide the best option to analyze core-valence double hole spectra.

  10. Deficits in Sustained Attention and Changes in Dopaminergic Protein Levels following Exposure to Proton Radiation Are Related to Basal Dopaminergic Function.

    PubMed

    Davis, Catherine M; DeCicco-Skinner, Kathleen L; Hienz, Robert D

    2015-01-01

    The current report assessed the effects of low-level proton irradiation in inbred adult male Fischer 344 and Lewis rats performing an analog of the human Psychomotor Vigilance Test (PVT), commonly utilized as an object risk assessment tool to quantify fatigue and sustained attention in laboratory, clinical, and operational settings. These strains were used to determine if genetic differences in dopaminergic function would impact radiation-induced deficits in sustained attention. Exposure to head-only proton irradiation (25 or 100 cGy) disrupted rPVT performance in a strain-specific manner, with 25 cGy-exposed Fischer 344 rats displaying the most severe deficits in sustained attention (i.e., decreased accuracy and increased premature responding); Lewis rats did not display behavioral deficits following radiation. Fischer 344 rats displayed greater tyrosine hydroxylase and dopamine transporter levels in the frontal cortex compared to the Lewis rats, even though radiation exposure increased both of these proteins in the Lewis rats only. Tyrosine hydroxylase was decreased in the parietal cortex of both rat strains following radiation exposure, regardless of proton dose. Strain-specific cytokine changes were also found in the frontal cortex, with the Lewis rats displaying increased levels of putative neurotrophic cytokines (e.g., CNTF). These data support the hypothesis that basal dopaminergic function impacts the severity of radiation-induced deficits in sustained attention.

  11. High-resolution laser spectroscopy with the Collinear Resonance Ionisation Spectroscopy (CRIS) experiment at CERN-ISOLDE

    NASA Astrophysics Data System (ADS)

    Cocolios, T. E.; de Groote, R. P.; Billowes, J.; Bissell, M. L.; Budinčević, I.; Day Goodacre, T.; Farooq-Smith, G. J.; Fedosseev, V. N.; Flanagan, K. T.; Franchoo, S.; Garcia Ruiz, R. F.; Gins, W.; Heylen, H.; Kron, T.; Li, R.; Lynch, K. M.; Marsh, B. A.; Neyens, G.; Rossel, R. E.; Rothe, S.; Smith, A. J.; Stroke, H. H.; Wendt, K. D. A.; Wilkins, S. G.; Yang, X.

    2016-06-01

    The Collinear Resonance Ionisation Spectroscopy (CRIS) experiment at CERN has achieved high-resolution resonance ionisation laser spectroscopy with a full width at half maximum linewidth of 20(1) MHz for 219,221 Fr, and has measured isotopes as short lived as 5 ms with 214 Fr. This development allows for greater precision in the study of hyperfine structures and isotope shifts, as well as a higher selectivity of single-isotope, even single-isomer, beams. These achievements are linked with the development of a new laser laboratory and new data-acquisition systems.

  12. Correlation of the ionisation response at selected points of IC sensitive regions with SEE sensitivity parameters under pulsed laser irradiation

    SciTech Connect

    Gordienko, A V; Mavritskii, O B; Egorov, A N; Pechenkin, A A; Savchenkov, D V

    2014-12-31

    The statistics of the ionisation response amplitude measured at selected points and their surroundings within sensitive regions of integrated circuits (ICs) under focused femtosecond laser irradiation is obtained for samples chosen from large batches of two types of ICs. A correlation between these data and the results of full-chip scanning is found for each type. The criteria for express validation of IC single-event effect (SEE) hardness based on ionisation response measurements at selected points are discussed. (laser applications and other topics in quantum electronics)

  13. Effects of ionised or chelated water-soluble mineral mixture supplementation on growth performance, nutrient digestibility, blood characteristics, meat quality and intestinal microbiota in broilers.

    PubMed

    Upadhaya, S D; Lee, B R; Kim, I H

    2016-04-01

    An experiment was conducted to study the effects of dietary supplementation of water-soluble ionised or chelated mineral mixture on growth performance, nutrient digestibility, blood characteristics, relative organ weight, meat quality and excreta microflora in broilers. A total of 408 Arbor Acres broilers (17 birds in 8 replicate pens) were randomly allocated into one of the following three treatments: (1) Control/basal diet (CON), (2) T1 (basal diet + 0.5% ionised mineral mixture solution, pH 3.0) and (3) T2 (basal diet + 0.5% chelated mineral mixture solution, pH 3.0). The body weight gain was greater and feed conversion ratio was lower in broilers supplemented with ionised or chelated mineral liquid complex compared to CON during the grower and overall phase of the experiment. No significant effect in the concentration of Ca and P in the blood was observed in birds supplemented with ionised or chelated mineral mixture solution. No adverse effects were observed in organ weight and meat quality with ionised or chelated mineral mixture supplementation. Regarding intestinal microbiota counts there was a reduction of Escherichia coli counts in the small intestine in ionised mineral supplemented birds. In the large intestine, E. coli as well as Salmonella populations were reduced in ionised mineral supplemented birds. In conclusion, ionised or chelated minerals have partial positive effects in improving growth performance and reducing pathogenic bacteria load in the gastro-intestinal tract.

  14. Evaluation of Ki-67 Staining Levels as an Independent Biomarker of Biochemical Recurrence After Salvage Radiation Therapy for Prostate Cancer

    SciTech Connect

    Parker, Alexander S.; Heckman, Michael G.; Wu, Kevin J.; Crook, Julia E.; Hilton, Tracy W.; Pisansky, Thomas M.; Bernard, Johnny R.; Schild, Steven E.; Khor, Li Yan; Hammond, Elizabeth H.; Pollack, Alan; Buskirk, Steven J.

    2009-12-01

    Purpose: We recently published a scoring algorithm to predict biochemical recurrence (BCR) after salvage radiation therapy (SRT) for prostate cancer. Currently, this algorithm is based on clinicopathologic features and does not incorporate information from tumor-based biomarkers. Herein, we evaluate the ability of Ki-67 staining in primary prostate cancer to independently aid in the prediction of BCR among men undergoing SRT. Methods and Materials: We identified 147 patients who were treated with SRT between July 1987 and July 2003 at Mayo Clinic (Rochester, MN; Jacksonville, FL; Scottsdale, AZ). Staining levels of Ki-67 in primary tumor samples were detected by use of a monoclonal antibody and quantified by use of a computer-assisted method. We used Cox proportional hazards models to examine the association of Ki-67 staining and BCR in single-variable models and after multivariable adjustment. Results: The risk of BCR for men with tumors in the highest tertile of Ki-67 staining is approximately two times that for men with tumors in the lower two tertiles (relative risk, 2.02; 95% confidence interval, 1.23-3.32; p = 0.005) after adjustment for the features in our original scoring algorithm. Further adjustment for additional covariates did not attenuate this association. Evidence from concordance index values supports that Ki-67 staining adds to the predictive ability of our existing scoring algorithm. Conclusions: Our data suggest that higher levels of Ki-67 staining are associated with increased risk of BCR after SRT, independent of existing clinicopathologic covariates. Future studies involving larger numbers of patients are required to validate these results and also explore possible means of combining this biomarker with existing prognostic tools.

  15. SU-E-T-573: Normal Tissue Dose Effect of Prescription Isodose Level Selection in Lung Stereotactic Body Radiation Therapy

    SciTech Connect

    Zhang, Q; Lei, Y; Zheng, D; Zhu, X; Wahl, A; Lin, C; Zhou, S; Zhen, W

    2015-06-15

    Purpose: To evaluate dose fall-off in normal tissue for lung stereotactic body radiation therapy (SBRT) cases planned with different prescription isodose levels (IDLs), by calculating the dose dropping speed (DDS) in normal tissue on plans computed with both Pencil Beam (PB) and Monte-Carlo (MC) algorithms. Methods: The DDS was calculated on 32 plans for 8 lung SBRT patients. For each patient, 4 dynamic conformal arc plans were individually optimized for prescription isodose levels (IDL) ranging from 60% to 90% of the maximum dose with 10% increments to conformally cover the PTV. Eighty non-overlapping rind structures each of 1mm thickness were created layer by layer from each PTV surface. The average dose in each rind was calculated and fitted with a double exponential function (DEF) of the distance from the PTV surface, which models the steep- and moderate-slope portions of the average dose curve in normal tissue. The parameter characterizing the steep portion of the average dose curve in the DEF quantifies the DDS in the immediate normal tissue receiving high dose. Provided that the prescription dose covers the whole PTV, a greater DDS indicates better normal tissue sparing. The DDS were compared among plans with different prescription IDLs, for plans computed with both PB and MC algorithms. Results: For all patients, the DDS was found to be the lowest for 90% prescription IDL and reached a highest plateau region for 60% or 70% prescription. The trend was the same for both PB and MC plans. Conclusion: Among the range of prescription IDLs accepted by lung SBRT RTOG protocols, prescriptions to 60% and 70% IDLs were found to provide best normal tissue sparing.

  16. Total effective dose equivalent assessment after exposure to high-level natural radiation using the RESRAD code.

    PubMed

    Ziajahromi, Shima; Khanizadeh, Meysam; Nejadkoorki, Farhad

    2014-03-01

    The current work reports the activity concentrations of several natural radionuclides ((226)Ra, (232)Th, and (40)K) in Khak-Sefid area of Ramsar, Iran. An evaluation of total effective dose equivalent (TEDE) from exposure to high-level natural radiations is also presented. Soil samples were analyzed using a high-purity germanium detector with 80 % relative efficiency. The TEDE was calculated on a land area of 40,000 m(2) with 1.5-m thickness of contaminated zone for the member of three critical groups of farmer, construction worker, and resident using Residual Radioactive Material Guidelines (RESRAD) modeling program. It was found that the mean activity concentrations (in Bq/kg) were 23,118 ± 468, 25.8 ± 2.3, and 402.6 ± 16.5 for (226)Ra, (232)Th, and (40)K, respectively. The maximum calculated TEDE during 1,000 years was 107.1 mSv/year at year 90, 92.42 mSv/year at year 88, and 22.09 mSv/year at year 46 for farmer, resident, and construction worker scenarios, respectively. The maximum TEDE in farmer scenario can be reduced to the level below the dose limit of 1 mSv/year which is safe for public health using soil cover with thickness of 50 cm or more on the contaminated zone. According to RESRAD prediction, the TEDE received by individuals for all exposure scenarios considerably exceed the set dose limit, and it is mainly due to (226)Ra.

  17. Personal radiation detector at a high technology readiness level that satisfies DARPA's SN-13-47 and SIGMA program requirements

    NASA Astrophysics Data System (ADS)

    Ginzburg, D.; Knafo, Y.; Manor, A.; Seif, R.; Ghelman, M.; Ellenbogen, M.; Pushkarsky, V.; Ifergan, Y.; Semyonov, N.; Wengrowicz, U.; Mazor, T.; Kadmon, Y.; Cohen, Y.; Osovizky, A.

    2015-06-01

    There is a need to develop new personal radiation detector (PRD) technologies that can be mass produced. On August 2013, DARPA released a request for information (RFI) seeking innovative radiation detection technologies. In addition, on December 2013, a Broad Agency Announcement (BAA) for the SIGMA program was released. The RFI requirements focused on a sensor that should possess three main properties: low cost, high compactness and radioisotope identification capabilities. The identification performances should facilitate the detection of a hidden threat, ranging from special nuclear materials (SNM) to commonly used radiological sources. Subsequently, the BAA presented the specific requirements at an instrument level and provided a comparison between the current market status (state-of-the-art) and the SIGMA program objectives. This work presents an optional alternative for both the detection technology (sensor with communication output and without user interface) for DARPA's initial RFI and for the PRD required by the SIGMA program. A broad discussion is dedicated to the method proposed to fulfill the program objectives and to the selected alternative that is based on the PDS-GO design and technology. The PDS-GO is the first commercially available PRD that is based on a scintillation crystal optically coupled with a silicon photomultiplier (SiPM), a solid-state light sensor. This work presents the current performance of the instrument and possible future upgrades based on recent technological improvements in the SiPM design. The approach of utilizing the SiPM with a commonly available CsI(Tl) crystal is the key for achieving the program objectives. This approach provides the appropriate performance, low cost, mass production and small dimensions; however, it requires a creative approach to overcome the obstacles of the solid-state detector dark current (noise) and gain stabilization over a wide temperature range. Based on the presented results, we presume that

  18. The Level of Europium-154 Contaminating Samarium-153-EDTMP Activates the Radiation Alarm System at the US Homeland Security Checkpoints.

    PubMed

    Najeeb Al Hallak, Mohammed; McCurdy, Matt; Zouain, Nicolas; Hayes, Justin

    2009-08-28

    (153)Sm-EDTMP is a radiopharmaceutical composed of EDTMP (ethylenediamine-tetramethylenephosphonate) and Samarium-153 [1]. (153)Sm-EDTMP has an affinity for skeletal tissue and concentrates in areas with increased bone turnover; thus, it is successfully used in relieving pain related to diffuse bone metastases [1]. The manufacturing process of (153)Sm-EDTMP leads to contamination with (154)Eu (Europium-154) [2]. A previous study only alluded to the retention of (154)Eu in the bones after receiving treatment with (153)Sm-EDTMP [2]. Activation of the alarm at security checkpoints after (153)Sm-EDTMP therapy has not been previously reported. Two out of 15 patients who received (153)Sm-EDTMP at Roger Maris Cancer Center (Fargo, N. Dak., USA) activated the radiation activity sensors while passing through checkpoints; one at a US airport and the other while crossing the American-Canadian border. We assume that the (154)Eu which remained in the patients' bones activated the sensors. METHODS: In order to investigate this hypothesis, we obtained the consent from 3 of our 15 patients who received (153)Sm-EDTMP within the previous 4 months to 2 years, including the patient who had activated the radiation alarm at the airport. The patients were scanned with a handheld detector and a gamma camera for energies from 511 keV to 1.3 MeV. RESULTS: All three patients exhibited identical spectral images, and further analysis showed that the observed spectra are the result of (154)Eu emissions. CONCLUSION: Depending on the detection thresholds and windows used by local and federal authorities, the remaining activity of (154)Eu retained in patients who received (153)Sm-EDTMP could be sufficient enough to increase the count rates above background levels and activate the sensors. At Roger Maris Cancer Center, patients are now informed of the potential consequences of (153)Sm-EDTMP therapy prior to initiating treatment. In addition, patients treated with (153)Sm-EDTMP at Roger Maris Cancer

  19. Induction of p53 protein by gamma radiation in lymphocyte lines from breast cancer and ataxia telangiectasia patients.

    PubMed Central

    Birrell, G. W.; Ramsay, J. R.

    1995-01-01

    Exposure of human cells to gamma-radiation causes levels of the tumour-suppressor nuclear protein p53 to increase in temporal association with the decrease in replicative DNA synthesis. Cells from patients with the radiosensitive and cancer-prone disease ataxia telangiectasia (AT) exhibit radioresistant DNA synthesis and show a reduced or delayed gamma-radiation-induced increase in p53 protein levels. We have used Western immunoblotting with semiquantitative densitometry to examine the gamma-radiation-induced levels of p53 protein in 57 lymphoblastoid cell lines (LCLs) derived from patients with AT, carriers of the AT gene, breast cancer patients and normal donors. We confirm the previously reported reduced induction in AT homozygote LCLs (n = 8) compared with normal donor LCLs (n = 17, P = 0.01). We report that AT heterozygote LCLs (n = 5) also have a significantly reduced p53 induction when compared with LCLs from normal donors (n = 17, P = 0.02). The response of breast cancer patient cells was not significantly different from normal donor cells but 18% (5/27) had a p53 response in the AT heterozygote range (95% confidence interval) compared with only 6% (1/17) of the normal donor cells. We found no significant correlation between p53 induction and cellular radiosensitivity in LCLs from breast cancer patients. These methods may be useful in identifying individuals at greater risk of the DNA-damaging effects of ionising radiation. Images Figure 2 PMID:7577453

  20. Plasma formation on a metal surface under combined action of laser and microwave radiation

    SciTech Connect

    Gavrilyuk, A P; Shaparev, N Ya

    2013-10-31

    By means of numerical modelling of the combined effect of laser (1.06 mm) and microwave (10{sup 10} – 10{sup 13} s{sup -1}) radiation on the aluminium surface in vacuum it is shown that the additional action of microwave radiation with the frequency 10{sup 12} s{sup -1} provides complete ionisation of the metal vapour (for the values of laser radiation duration and intensity used in the calculations), while in the absence of microwave radiation the vapour remains weakly ionised. The mathematical model used accounts for the processes, occurring in the condensed phase (heat conduction, melting), the evaporation and the kinetic processes in the resulting vapour. (interaction of laser radiation with matter. laser plasma)