WorldWideScience

Sample records for adaptive radiation

  1. Epigenomic Adaptation to Low Dose Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Gould, Michael N. [Univ. of Wisconsin, Madison, WI (United States)

    2015-06-30

    The overall hypothesis of this grant application is that the adaptive responses elicited by low dose ionizing radiation (LDIR) result in part from heritable DNA methylation changes in the epigenome. In the final budget period at the University of Wisconsin-Madison, we will specifically address this hypothesis by determining if the epigenetically labile, differentially methylated regions (DMRs) that regulate parental-specific expression of imprinted genes are deregulated in agouti mice by low dose radiation exposure during gestation. This information is particularly important to ascertain given the 1) increased human exposure to medical sources of radiation; 2) increased number of people predicted to live and work in space; and 3) enhanced citizen concern about radiation exposure from nuclear power plant accidents and terrorist ‘dirty bombs.’

  2. Evolution of Genetic Variance during Adaptive Radiation.

    Science.gov (United States)

    Walter, Greg M; Aguirre, J David; Blows, Mark W; Ortiz-Barrientos, Daniel

    2018-04-01

    Genetic correlations between traits can concentrate genetic variance into fewer phenotypic dimensions that can bias evolutionary trajectories along the axis of greatest genetic variance and away from optimal phenotypes, constraining the rate of evolution. If genetic correlations limit adaptation, rapid adaptive divergence between multiple contrasting environments may be difficult. However, if natural selection increases the frequency of rare alleles after colonization of new environments, an increase in genetic variance in the direction of selection can accelerate adaptive divergence. Here, we explored adaptive divergence of an Australian native wildflower by examining the alignment between divergence in phenotype mean and divergence in genetic variance among four contrasting ecotypes. We found divergence in mean multivariate phenotype along two major axes represented by different combinations of plant architecture and leaf traits. Ecotypes also showed divergence in the level of genetic variance in individual traits and the multivariate distribution of genetic variance among traits. Divergence in multivariate phenotypic mean aligned with divergence in genetic variance, with much of the divergence in phenotype among ecotypes associated with changes in trait combinations containing substantial levels of genetic variance. Overall, our results suggest that natural selection can alter the distribution of genetic variance underlying phenotypic traits, increasing the amount of genetic variance in the direction of natural selection and potentially facilitating rapid adaptive divergence during an adaptive radiation.

  3. Tissues may adapt to radiation exposure

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    French scientists discovered radioactivity and developed vaccination, so it is perhaps appropriate that a prominent French cancer specialist should be promoting the idea of a radiation vaccination effect - or radiation adaptation, as he prefers to call it. Raymond Latarjet, of the Institut Curie in Paris, maintains that recent studies at the gene level are showing evidence that with low doses of radiation, there is time for a cell repair mechanism to take effect, and that this seems to provide some protection against subsequent exposure to high doses. He cited experiments in his laboratory in which exposure to a dose of 4 Gy (400 rad) had, predictably, produced a large number of gene mutations in a specimen, but the number of mutations was less than half that number in a specimen that had been exposed to a dose of 0.02 Gy some six hours before exposure to the 4 Gy

  4. Tissues may adapt to radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-08-01

    French scientists discovered radioactivity and developed vaccination, so it is perhaps appropriate that a prominent French cancer specialist should be promoting the idea of a radiation vaccination effect - or radiation adaptation, as he prefers to call it. Raymond Latarjet, of the Institut Curie in Paris, maintains that recent studies at the gene level are showing evidence that with low doses of radiation, there is time for a cell repair mechanism to take effect, and that this seems to provide some protection against subsequent exposure to high doses. He cited experiments in his laboratory in which exposure to a dose of 4 Gy (400 rad) had, predictably, produced a large number of gene mutations in a specimen, but the number of mutations was less than half that number in a specimen that had been exposed to a dose of 0.02 Gy some six hours before exposure to the 4 Gy.

  5. Sparse adaptive finite elements for radiative transfer

    International Nuclear Information System (INIS)

    Widmer, G.; Hiptmair, R.; Schwab, Ch.

    2008-01-01

    The linear radiative transfer equation, a partial differential equation for the radiation intensity u(x,s), with independent variables x element of D is contained in R n in the physical domain D of dimension n=2,3, and angular variable s element of S 2 :={y element of R 3 :|y|=1}, is solved in the n+2-dimensional computational domain DxS 2 . We propose an adaptive multilevel Galerkin finite element method (FEM) for its numerical solution. Our approach is based on (a) a stabilized variational formulation of the transport operator, (b) on so-called sparse tensor products of two hierarchic families of finite element spaces in H 1 (D) and in L 2 (S 2 ), respectively, and (c) on wavelet thresholding techniques to adapt the discretization to the underlying problem. An a priori error analysis shows, under strong regularity assumptions on the solution, that the sparse tensor product method is clearly superior to a discrete ordinates method, as it converges with essentially optimal asymptotic rates while its complexity grows essentially only as that for a linear transport problem in R n . Numerical experiments for n=2 on a set of example problems agree with the convergence and complexity analysis of the method and show that introducing adaptivity can improve performance in terms of accuracy vs. number of degrees even further

  6. Adaptive response to high LET radiations

    International Nuclear Information System (INIS)

    Dam, Annamaria; Bogdandi, E. Noemi; Polonyi, Istvan; Sardy, M. Marta; Balashazy, Imre; Palfalvy, Jozsef

    2001-01-01

    The biological consequences of exposure to ionizing radiation include gene mutation, chromosome aberrations, cellular transformation and cell death. These effects are attributed to the DNA damaging effects of the irradiation resulting in irreversible changes during DNA replication or during the processing of the DNA damage by enzymatic repair processes. These repair processes could initiate some adaptive mechanisms in the cell, which could lead to radioadaptive response (RAR). Adaptive responses have typically been detected by exposing cells to a low radiation dose (1-50 mGy) and then challenging the cells with a higher dose of radiation (2-4 Gy) and comparing the outcome to that seen with the challenge dose only. For adaptive response to be seen the challenge dose must be delivered within 24 hour of the inducing dose. Radio-adaptation is extensively studied for low LET radiation. Nevertheless, few data are available for high LET radiation at very low doses and dose rate. Our study was aimed to investigate the radioadaptive response to low-dose neutron irradiation by detection of the genotoxic damage i.e.: hprt-mutant colonies induced. Altered protein synthesis was also studied to identify stress proteins may responsible for radio-adaptation. New alpha particle irradiator system was also built up to study the biological effects of low dose alpha irradiation. The experiments were carried out on monolayers of human melanoma and CHO (Chines Hamster Ovary) cells irradiated by neutrons produced in the biological irradiation channel of the Research Reactor of Budapest Neutron Center. Cells were exposed to 0.5-50 mGy neutron doses with dose rates of 1.59-10 mGy/min. The challenge doses of 2-4 Gy gamma rays were administrated within 1-48 hours after priming treatment. The induced mutants at hprt locus were selected by adding 6-thioguanine and allow to grow for 10 days for expression of the phenotype. The protein synthesis was studied by PAGE, the molecular mass of specific

  7. Shape Morphing Adaptive Radiator Technology (SMART) for Variable Heat Rejection

    Science.gov (United States)

    Erickson, Lisa

    2016-01-01

    The proposed technology leverages the temperature dependent phase change of shape memory alloys (SMAs) to drive the shape of a flexible radiator panel. The opening/closing of the radiator panel, as a function of temperature, passively adapts the radiator's rate of heat rejection in response to a vehicle's needs.

  8. Automatic Organ Localization for Adaptive Radiation Therapy for Prostate Cancer

    National Research Council Canada - National Science Library

    Joshi, Sarang

    2004-01-01

    The focus of this study is adaptive radiation therapy (ART) for prostate cancer, in which the treatment is to be adjusted over time, based on CT images acquired on the treatment table before each daily treatment...

  9. Biological Bases for Radiation Adaptive Responses in the Lung

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Bobby R. [Lovelace Biomedical and Environmental Research Inst., Albuquerque, NM (United States); Lin, Yong [Lovelace Biomedical and Environmental Research Inst., Albuquerque, NM (United States); Wilder, Julie [Lovelace Biomedical and Environmental Research Inst., Albuquerque, NM (United States); Belinsky, Steven [Lovelace Biomedical and Environmental Research Inst., Albuquerque, NM (United States)

    2015-03-01

    Our main research objective was to determine the biological bases for low-dose, radiation-induced adaptive responses in the lung, and use the knowledge gained to produce an improved risk model for radiation-induced lung cancer that accounts for activated natural protection, genetic influences, and the role of epigenetic regulation (epiregulation). Currently, low-dose radiation risk assessment is based on the linear-no-threshold hypothesis, which now is known to be unsupported by a large volume of data.

  10. Ecological opportunity and sexual selection together predict adaptive radiation.

    Science.gov (United States)

    Wagner, Catherine E; Harmon, Luke J; Seehausen, Ole

    2012-07-19

    A fundamental challenge to our understanding of biodiversity is to explain why some groups of species undergo adaptive radiations, diversifying extensively into many and varied species, whereas others do not. Both extrinsic environmental factors (for example, resource availability, climate) and intrinsic lineage-specific traits (for example, behavioural or morphological traits, genetic architecture) influence diversification, but few studies have addressed how such factors interact. Radiations of cichlid fishes in the African Great Lakes provide some of the most dramatic cases of species diversification. However, most cichlid lineages in African lakes have not undergone adaptive radiations. Here we compile data on cichlid colonization and diversification in 46 African lakes, along with lake environmental features and information about the traits of colonizing cichlid lineages, to investigate why adaptive radiation does and does not occur. We find that extrinsic environmental factors related to ecological opportunity and intrinsic lineage-specific traits related to sexual selection both strongly influence whether cichlids radiate. Cichlids are more likely to radiate in deep lakes, in regions with more incident solar radiation and in lakes where there has been more time for diversification. Weak or negative associations between diversification and lake surface area indicate that cichlid speciation is not constrained by area, in contrast to diversification in many terrestrial taxa. Among the suite of intrinsic traits that we investigate, sexual dichromatism, a surrogate for the intensity of sexual selection, is consistently positively associated with diversification. Thus, for cichlids, it is the coincidence between ecological opportunity and sexual selection that best predicts whether adaptive radiation will occur. These findings suggest that adaptive radiation is predictable, but only when species traits and environmental factors are jointly considered.

  11. Adaptive search and detection of laser radiation

    International Nuclear Information System (INIS)

    Efendiev, F.A.; Kasimova, F.I.

    2008-01-01

    Formation of cosmic optical line connected with the solving of difficult problems, among which stand out spatial search task, detection and target tracking. Indeed, the main advantage of systems of the optical diapason, high radiation direction leads to a challenging task of entering in communication, consisting in mutual targeting antenna receiving and transmitting systems. Algorithm detection, obtained by solving the corresponding statistical optimal detection test synthesis tasks detector determines the structure and quality of his work which depend on the average characteristics of the signal and the background radiation of the thermal noise require full priori certainty about the conditions of observation. Algorithm of the optimal detector of laser light modulated on a sub carrier frequency of intensity assumes a priori known intensity and efficiency background radiation and internal noise power photo detector

  12. Direct aperture optimization for online adaptive radiation therapy

    International Nuclear Information System (INIS)

    Mestrovic, Ante; Milette, Marie-Pierre; Nichol, Alan; Clark, Brenda G.; Otto, Karl

    2007-01-01

    This paper is the first investigation of using direct aperture optimization (DAO) for online adaptive radiation therapy (ART). A geometrical model representing the anatomy of a typical prostate case was created. To simulate interfractional deformations, four different anatomical deformations were created by systematically deforming the original anatomy by various amounts (0.25, 0.50, 0.75, and 1.00 cm). We describe a series of techniques where the original treatment plan was adapted in order to correct for the deterioration of dose distribution quality caused by the anatomical deformations. We found that the average time needed to adapt the original plan to arrive at a clinically acceptable plan is roughly half of the time needed for a complete plan regeneration, for all four anatomical deformations. Furthermore, through modification of the DAO algorithm the optimization search space was reduced and the plan adaptation was significantly accelerated. For the first anatomical deformation (0.25 cm), the plan adaptation was six times more efficient than the complete plan regeneration. For the 0.50 and 0.75 cm deformations, the optimization efficiency was increased by a factor of roughly 3 compared to the complete plan regeneration. However, for the anatomical deformation of 1.00 cm, the reduction of the optimization search space during plan adaptation did not result in any efficiency improvement over the original (nonmodified) plan adaptation. The anatomical deformation of 1.00 cm demonstrates the limit of this approach. We propose an innovative approach to online ART in which the plan adaptation and radiation delivery are merged together and performed concurrently--adaptive radiation delivery (ARD). A fundamental advantage of ARD is the fact that radiation delivery can start almost immediately after image acquisition and evaluation. Most of the original plan adaptation is done during the radiation delivery, so the time spent adapting the original plan does not

  13. On the adaptive conception in radiation hygiene

    International Nuclear Information System (INIS)

    Shepelin, O.P.

    1993-01-01

    The article presents the assessments of human adoptation capabilities under extreme conditions as for instance, after the Chernobyl accident (1986). It is shown that the problem of comprehensive assessment of radiation factor impact on the human population shall take into account the scope of accident, heaviness of the after effects of medicobiological, socioeconomic and moral-psycological nature

  14. Shape Morphing Adaptive Radiator Technology (SMART) Updates to Techport Entry

    Science.gov (United States)

    Erickson, Lisa; Bertagne, Christopher; Hartl, Darren; Witcomb, John; Cognata, Thomas

    2017-01-01

    The Shape-Morphing Adaptive Radiator Technology (SMART) project builds off the FY16 research effort that developed a flexible composite radiator panel and demonstrated its ability to actuate from SMA's attached to it. The proposed FY17 Shape-Morphing Adaptive Radiator Technology (SMART) project's goal is to 1) develop a practical radiator design with shape memory alloys (SMAs) bonded to the radiator's panel, and 2) build a multi-panel radiator prototype for subsequent system level thermal vacuum tests. The morphing radiator employs SMA materials to passively change its shape to adapt its rate of heat rejection to vehicle requirements. Conceptually, the radiator panel has a naturally closed position (like a cylinder) in a cold environment. Whenever the radiator's temperature gradually rises, SMA's affixed to the face sheet will pull the face sheet open a commensurate amount - increasing the radiators view to space and causing it to reject more heat. In a vehicle, the radiator's variable heat rejection capabilities would reduce the number of additional heat rejection devices in a vehicle's thermal control system. This technology aims to help achieve the required maximum to minimum heat rejection ratio required for manned space vehicles to adopt a lighter, simpler, single loop thermal control architecture (ATCS). Single loop architectures are viewed as an attractive means to reduce mass and complexity over traditional dual-loop solutions. However, fluids generally considered safe enough to flow within crewed cabins (e.g. propylene glycol-water mixtures) have much higher freezing points and viscosities than those used in the external sides of dual loop ATCSs (e.g. Ammonia and HFE7000).

  15. Genotypic sex determination enabled adaptive radiations of extinct marine reptiles.

    Science.gov (United States)

    Organ, Chris L; Janes, Daniel E; Meade, Andrew; Pagel, Mark

    2009-09-17

    Adaptive radiations often follow the evolution of key traits, such as the origin of the amniotic egg and the subsequent radiation of terrestrial vertebrates. The mechanism by which a species determines the sex of its offspring has been linked to critical ecological and life-history traits but not to major adaptive radiations, in part because sex-determining mechanisms do not fossilize. Here we establish a previously unknown coevolutionary relationship in 94 amniote species between sex-determining mechanism and whether a species bears live young or lays eggs. We use that relationship to predict the sex-determining mechanism in three independent lineages of extinct Mesozoic marine reptiles (mosasaurs, sauropterygians and ichthyosaurs), each of which is known from fossils to have evolved live birth. Our results indicate that each lineage evolved genotypic sex determination before acquiring live birth. This enabled their pelagic radiations, where the relatively stable temperatures of the open ocean constrain temperature-dependent sex determination in amniote species. Freed from the need to move and nest on land, extreme physical adaptations to a pelagic lifestyle evolved in each group, such as the fluked tails, dorsal fins and wing-shaped limbs of ichthyosaurs. With the inclusion of ichthyosaurs, mosasaurs and sauropterygians, genotypic sex determination is present in all known fully pelagic amniote groups (sea snakes, sirenians and cetaceans), suggesting that this mode of sex determination and the subsequent evolution of live birth are key traits required for marine adaptive radiations in amniote lineages.

  16. The link between bacterial radiation resistance and cold adaptation

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Biosciences; Volume 27; Issue 2. Clipboard: The link between bacterial radiation resistance and cold adaptation. M K Chattopadhyay. Volume 27 Issue 2 March 2002 pp 71-73. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/jbsc/027/02/0071-0073 ...

  17. Conserved sex chromosomes across adaptively radiated anolis lizards

    Czech Academy of Sciences Publication Activity Database

    Rovatsos, M.; Altmanová, M.; Pokorná, Martina; Kratochvíl, L.

    2014-01-01

    Roč. 68, č. 7 (2014), s. 2079-2085 ISSN 0014-3820 R&D Projects: GA ČR GAP506/10/0718 Institutional support: RVO:67985904 Keywords : adaptive radiation * Anolis * reptiles Subject RIV: EG - Zoology Impact factor: 4.612, year: 2014

  18. Radiation protection concepts review with an adapted quiz commercial game

    International Nuclear Information System (INIS)

    Rodrigues Junior, Ary de Araujo

    2002-01-01

    Before a new employee starts working at EMBRARAD under a large irradiation operator supervision, he has to attend the first radiation protection training. After that all radiation protection subjects are revised every six months. In that half-yearly training the employees are chosen randomly to explain radiation protection subjects to other participants under an instructor supervision. After some years attending the same training, employees do not have motivation to participate in this kind of periodic event due to the same issues covered. Therefore something should be made to revival their interest and motivation to take part in this periodic training. The way chose was adapted a commercial game to revised radiation protection subjects and included it in the periodic training. The game was well accepted by the employees, it caused a competition among them because everybody wanted to win the game and consequently stimulated them to study. (author)

  19. Adaptation of radiation shielding code to space environment

    International Nuclear Information System (INIS)

    Okuno, Koichi; Hara, Akihisa

    1992-01-01

    Recently, the trend to the development of space has heightened. To the development of space, many problems are related, and as one of them, there is the protection from cosmic ray. The cosmic ray is the radiation having ultrahigh energy, and there was not the radiation shielding design code that copes with cosmic ray so far. Therefore, the high energy radiation shielding design code for accelerators was improved so as to cope with the peculiarity that cosmic ray possesses. Moreover, the calculation of the radiation dose equivalent rate in the moon base to which the countermeasures against cosmic ray were taken was simulated by using the improved code. As the important countermeasures for the safety protection from radiation, the covering with regolith is carried out, and the effect of regolith was confirmed by using the improved code. Galactic cosmic ray, solar flare particles, radiation belt, the adaptation of the radiation shielding code HERMES to space environment, the improvement of the three-dimensional hadron cascade code HETCKFA-2 and the electromagnetic cascade code EGS 4-KFA, and the cosmic ray simulation are reported. (K.I.)

  20. Ecological opportunity and the origin of adaptive radiations.

    Science.gov (United States)

    Yoder, J B; Clancey, E; Des Roches, S; Eastman, J M; Gentry, L; Godsoe, W; Hagey, T J; Jochimsen, D; Oswald, B P; Robertson, J; Sarver, B A J; Schenk, J J; Spear, S F; Harmon, L J

    2010-08-01

    Ecological opportunity--through entry into a new environment, the origin of a key innovation or extinction of antagonists--is widely thought to link ecological population dynamics to evolutionary diversification. The population-level processes arising from ecological opportunity are well documented under the concept of ecological release. However, there is little consensus as to how these processes promote phenotypic diversification, rapid speciation and adaptive radiation. We propose that ecological opportunity could promote adaptive radiation by generating specific changes to the selective regimes acting on natural populations, both by relaxing effective stabilizing selection and by creating conditions that ultimately generate diversifying selection. We assess theoretical and empirical evidence for these effects of ecological opportunity and review emerging phylogenetic approaches that attempt to detect the signature of ecological opportunity across geological time. Finally, we evaluate the evidence for the evolutionary effects of ecological opportunity in the diversification of Caribbean Anolis lizards. Some of the processes that could link ecological opportunity to adaptive radiation are well documented, but others remain unsupported. We suggest that more study is required to characterize the form of natural selection acting on natural populations and to better describe the relationship between ecological opportunity and speciation rates.

  1. Plant's adaptive response under UV-B-radiation influence

    International Nuclear Information System (INIS)

    Danil'chenko, O.A.; Grodzinskij, D.M.

    2002-01-01

    Reduction of ozone layer, owing to anthropogenic contamination of an atmosphere results in increase of intensity of UV-radiation and shift of its spectrum in the short-wave side that causes strengthening of various biological effects of irradiation. Consequences of these processes may include increase of injuring of plants and decrease of productivity of agricultural crops to increased UV levels. The important significance in the plant's adaptation to different unfavorable factors has the plant's radioadaptive answer. It has been shown that radioadaptation of plants occurred not only after irradiation with g-radiation in low doses but after UV-rays action . Reaction of radioadaptation it seems to be nonspecific phenomenon in relation to type radiations

  2. Two adaptive radiative transfer schemes for numerical weather prediction models

    Directory of Open Access Journals (Sweden)

    V. Venema

    2007-11-01

    Full Text Available Radiative transfer calculations in atmospheric models are computationally expensive, even if based on simplifications such as the δ-two-stream approximation. In most weather prediction models these parameterisation schemes are therefore called infrequently, accepting additional model error due to the persistence assumption between calls. This paper presents two so-called adaptive parameterisation schemes for radiative transfer in a limited area model: A perturbation scheme that exploits temporal correlations and a local-search scheme that mainly takes advantage of spatial correlations. Utilising these correlations and with similar computational resources, the schemes are able to predict the surface net radiative fluxes more accurately than a scheme based on the persistence assumption. An important property of these adaptive schemes is that their accuracy does not decrease much in case of strong reductions in the number of calls to the δ-two-stream scheme. It is hypothesised that the core idea can also be employed in parameterisation schemes for other processes and in other dynamical models.

  3. Widespread parallel population adaptation to climate variation across a radiation: implications for adaptation to climate change.

    Science.gov (United States)

    Thorpe, Roger S; Barlow, Axel; Malhotra, Anita; Surget-Groba, Yann

    2015-03-01

    Global warming will impact species in a number of ways, and it is important to know the extent to which natural populations can adapt to anthropogenic climate change by natural selection. Parallel microevolution within separate species can demonstrate natural selection, but several studies of homoplasy have not yet revealed examples of widespread parallel evolution in a generic radiation. Taking into account primary phylogeographic divisions, we investigate numerous quantitative traits (size, shape, scalation, colour pattern and hue) in anole radiations from the mountainous Lesser Antillean islands. Adaptation to climatic differences can lead to very pronounced differences between spatially close populations with all studied traits showing some evidence of parallel evolution. Traits from shape, scalation, pattern and hue (particularly the latter) show widespread evolutionary parallels within these species in response to altitudinal climate variation greater than extreme anthropogenic climate change predicted for 2080. This gives strong evidence of the ability to adapt to climate variation by natural selection throughout this radiation. As anoles can evolve very rapidly, it suggests anthropogenic climate change is likely to be less of a conservation threat than other factors, such as habitat loss and invasive species, in this, Lesser Antillean, biodiversity hot spot. © 2015 John Wiley & Sons Ltd.

  4. The adaptive collision source method for discrete ordinates radiation transport

    International Nuclear Information System (INIS)

    Walters, William J.; Haghighat, Alireza

    2017-01-01

    Highlights: • A new adaptive quadrature method to solve the discrete ordinates transport equation. • The adaptive collision source (ACS) method splits the flux into n’th collided components. • Uncollided flux requires high quadrature; this is lowered with number of collisions. • ACS automatically applies appropriate quadrature order each collided component. • The adaptive quadrature is 1.5–4 times more efficient than uniform quadrature. - Abstract: A novel collision source method has been developed to solve the Linear Boltzmann Equation (LBE) more efficiently by adaptation of the angular quadrature order. The angular adaptation method is unique in that the flux from each scattering source iteration is obtained, with potentially a different quadrature order used for each. Traditionally, the flux from every iteration is combined, with the same quadrature applied to the combined flux. Since the scattering process tends to distribute the radiation more evenly over angles (i.e., make it more isotropic), the quadrature requirements generally decrease with each iteration. This method allows for an optimal use of processing power, by using a high order quadrature for the first iterations that need it, before shifting to lower order quadratures for the remaining iterations. This is essentially an extension of the first collision source method, and is referred to as the adaptive collision source (ACS) method. The ACS methodology has been implemented in the 3-D, parallel, multigroup discrete ordinates code TITAN. This code was tested on a several simple and complex fixed-source problems. The ACS implementation in TITAN has shown a reduction in computation time by a factor of 1.5–4 on the fixed-source test problems, for the same desired level of accuracy, as compared to the standard TITAN code.

  5. Deep reinforcement learning for automated radiation adaptation in lung cancer.

    Science.gov (United States)

    Tseng, Huan-Hsin; Luo, Yi; Cui, Sunan; Chien, Jen-Tzung; Ten Haken, Randall K; Naqa, Issam El

    2017-12-01

    To investigate deep reinforcement learning (DRL) based on historical treatment plans for developing automated radiation adaptation protocols for nonsmall cell lung cancer (NSCLC) patients that aim to maximize tumor local control at reduced rates of radiation pneumonitis grade 2 (RP2). In a retrospective population of 114 NSCLC patients who received radiotherapy, a three-component neural networks framework was developed for deep reinforcement learning (DRL) of dose fractionation adaptation. Large-scale patient characteristics included clinical, genetic, and imaging radiomics features in addition to tumor and lung dosimetric variables. First, a generative adversarial network (GAN) was employed to learn patient population characteristics necessary for DRL training from a relatively limited sample size. Second, a radiotherapy artificial environment (RAE) was reconstructed by a deep neural network (DNN) utilizing both original and synthetic data (by GAN) to estimate the transition probabilities for adaptation of personalized radiotherapy patients' treatment courses. Third, a deep Q-network (DQN) was applied to the RAE for choosing the optimal dose in a response-adapted treatment setting. This multicomponent reinforcement learning approach was benchmarked against real clinical decisions that were applied in an adaptive dose escalation clinical protocol. In which, 34 patients were treated based on avid PET signal in the tumor and constrained by a 17.2% normal tissue complication probability (NTCP) limit for RP2. The uncomplicated cure probability (P+) was used as a baseline reward function in the DRL. Taking our adaptive dose escalation protocol as a blueprint for the proposed DRL (GAN + RAE + DQN) architecture, we obtained an automated dose adaptation estimate for use at ∼2/3 of the way into the radiotherapy treatment course. By letting the DQN component freely control the estimated adaptive dose per fraction (ranging from 1-5 Gy), the DRL automatically favored dose

  6. Adaptive Stereotactic Body Radiation Therapy Planning for Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Yujiao [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Zhang, Fan [Occupational and Environmental Safety Office, Duke University Medical Center, Durham, North Carolina (United States); Yoo, David S.; Kelsey, Chris R. [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Yin, Fang-Fang [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Cai, Jing, E-mail: jing.cai@duke.edu [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States)

    2013-09-01

    Purpose: To investigate the dosimetric effects of adaptive planning on lung stereotactic body radiation therapy (SBRT). Methods and Materials: Forty of 66 consecutive lung SBRT patients were selected for a retrospective adaptive planning study. CBCT images acquired at each fraction were used for treatment planning. Adaptive plans were created using the same planning parameters as the original CT-based plan, with the goal to achieve comparable comformality index (CI). For each patient, 2 cumulative plans, nonadaptive plan (P{sub NON}) and adaptive plan (P{sub ADP}), were generated and compared for the following organs-at-risks (OARs): cord, esophagus, chest wall, and the lungs. Dosimetric comparison was performed between P{sub NON} and P{sub ADP} for all 40 patients. Correlations were evaluated between changes in dosimetric metrics induced by adaptive planning and potential impacting factors, including tumor-to-OAR distances (d{sub T-OAR}), initial internal target volume (ITV{sub 1}), ITV change (ΔITV), and effective ITV diameter change (Δd{sub ITV}). Results: 34 (85%) patients showed ITV decrease and 6 (15%) patients showed ITV increase throughout the course of lung SBRT. Percentage ITV change ranged from −59.6% to 13.0%, with a mean (±SD) of −21.0% (±21.4%). On average of all patients, P{sub ADP} resulted in significantly (P=0 to .045) lower values for all dosimetric metrics. Δd{sub ITV}/d{sub T-OAR} was found to correlate with changes in dose to 5 cc (ΔD5cc) of esophagus (r=0.61) and dose to 30 cc (ΔD30cc) of chest wall (r=0.81). Stronger correlations between Δd{sub ITV}/d{sub T-OAR} and ΔD30cc of chest wall were discovered for peripheral (r=0.81) and central (r=0.84) tumors, respectively. Conclusions: Dosimetric effects of adaptive lung SBRT planning depend upon target volume changes and tumor-to-OAR distances. Adaptive lung SBRT can potentially reduce dose to adjacent OARs if patients present large tumor volume shrinkage during the treatment.

  7. Conserved sex chromosomes across adaptively radiated Anolis lizards.

    Science.gov (United States)

    Rovatsos, Michail; Altmanová, Marie; Pokorná, Martina; Kratochvíl, Lukáš

    2014-07-01

    Vertebrates possess diverse sex-determining systems, which differ in evolutionary stability among particular groups. It has been suggested that poikilotherms possess more frequent turnovers of sex chromosomes than homoiotherms, whose effective thermoregulation can prevent the emergence of the sex reversals induced by environmental temperature. Squamate reptiles used to be regarded as a group with an extensive variability in sex determination; however, we document how the rather old radiation of lizards from the genus Anolis, known for exceptional ecomorphological variability, was connected with stability in sex chromosomes. We found that 18 tested species, representing most of the phylogenetic diversity of the genus, share the gene content of their X chromosomes. Furthermore, we discovered homologous sex chromosomes in species of two genera (Sceloporus and Petrosaurus) from the family Phrynosomatidae, serving here as an outgroup to Anolis. We can conclude that the origin of sex chromosomes within iguanas largely predates the Anolis radiation and that the sex chromosomes of iguanas remained conserved for a significant part of their evolutionary history. Next to therian mammals and birds, Anolis lizards therefore represent another adaptively radiated amniote clade with conserved sex chromosomes. We argue that the evolutionary stability of sex-determining systems may reflect an advanced stage of differentiation of sex chromosomes rather than thermoregulation strategy. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  8. Adaptation of the present concept of dosimetric radiation protection quantities for external radiation to radiation protection practice

    International Nuclear Information System (INIS)

    Boehm, J.; Thompson, I. M. G.

    2004-01-01

    The present concept of dosimetric radiation protection quantities for external radiation is reviewed. For everyday application of the concept some adaptations are recommended. The check of the compliance with dose limits should be performed either by the comparison with values of the respective operational quantities directly or by the calculation of the protection quantity by means of the operational quantity, the appertaining conversion coefficient and additional information of the radiation field. Only four operational quantities are regarded to be sufficient for most applications in radiation protection practice. The term equivalent should be used in the connection dose equivalent only. Proposals are made for names of frequently used operational quantities which are denoted up to now by symbols only. (authors)

  9. Multiple factors participating in radiation-induced adaptive response

    International Nuclear Information System (INIS)

    Nenoi, Mitsuru; Vares, G.; Wang, Bing

    2009-01-01

    Radiation-induced adaptive response (RAR) is essentially the acquisition of radiation resistance by pre-exposed low dose radiation (priming). In this paper, in vitro findings on RAR-related factors are reviewed and authors' studies of RAR-related gene analysis in lethality and malformation of mouse fetus are described for future view. Studies on in vitro RAR have involved such participating factors as signal transduction, response appearance and bystander effect, and gene expression profiling. In RAR, DNA double strand break (DSB) by priming is conceivably the initial stimulation. In various cell systems including p53-knockout cells and in enzyme inhibition studies, intracellular signaling factors like protein kinase C, p38 MAPK, phospholipase C have been shown to participate. Increased activities of antioxidant and of damaged DNA repairing system, modulation of cell cycle, heat-shock reactions and apoptosis are suggested to concern to RAR appearance. Relationship between RAR and bystander effect is conceived to be important based on findings of cell lethality, mutagenesis, gap junction and NO radical. Genes relating to DSB repair, stress response, cell cycle and apoptosis have been shown to be specifically changed in RAR by their expression profile. Authors have conducted in vivo studies on RAR using embryogenetic system in the mouse. They have shown by gene profiling that signaling evoked by priming is important when the fetal lethality and malformation are used as RAR measures, and that in the subsequent process to RAR appearance, many signaling factors, particularly the transcription factor like p53, play a role. Database construction according to measures employed in individual studies, classification of living systems studied, radiation factors like linear energy transfer (LET), dose and dose rate, and functional genes concerned is thought useful for understanding the ultimate molecular mechanisms involved in ARA. (K.T.)

  10. Adaptive phenotypic plasticity in the Midas cichlid fish pharyngeal jaw and its relevance in adaptive radiation

    Directory of Open Access Journals (Sweden)

    Salzburger Walter

    2011-04-01

    Full Text Available Abstract Background Phenotypic evolution and its role in the diversification of organisms is a central topic in evolutionary biology. A neglected factor during the modern evolutionary synthesis, adaptive phenotypic plasticity, more recently attracted the attention of many evolutionary biologists and is now recognized as an important ingredient in both population persistence and diversification. The traits and directions in which an ancestral source population displays phenotypic plasticity might partly determine the trajectories in morphospace, which are accessible for an adaptive radiation, starting from the colonization of a novel environment. In the case of repeated colonizations of similar environments from the same source population this "flexible stem" hypothesis predicts similar phenotypes to arise in repeated subsequent radiations. The Midas Cichlid (Amphilophus spp. in Nicaragua has radiated in parallel in several crater-lakes seeded by populations originating from the Nicaraguan Great Lakes. Here, we tested phenotypic plasticity in the pharyngeal jaw of Midas Cichlids. The pharyngeal jaw apparatus of cichlids, a second set of jaws functionally decoupled from the oral ones, is known to mediate ecological specialization and often differs strongly between sister-species. Results We performed a common garden experiment raising three groups of Midas cichlids on food differing in hardness and calcium content. Analyzing the lower pharyngeal jaw-bones we find significant differences between diet groups qualitatively resembling the differences found between specialized species. Observed differences in pharyngeal jaw expression between groups were attributable to the diet's mechanical resistance, whereas surplus calcium in the diet was not found to be of importance. Conclusions The pharyngeal jaw apparatus of Midas Cichlids can be expressed plastically if stimulated mechanically during feeding. Since this trait is commonly differentiated - among

  11. An adaptive crystal bender for high power synchrotron radiation beams

    International Nuclear Information System (INIS)

    Berman, L.E.; Hastings, J.B.

    1992-01-01

    Perfect crystal monochromators cannot diffract x-rays efficiently, nor transmit the high source brightness available at synchrotron radiation facilities, unless surface strains within the beam footprint are maintained within a few arcseconds. Insertion devices at existing synchrotron sources already produce x-ray power density levels that can induce surface slope errors of several arcseconds on silicon monochromator crystals at room temperature, no matter how well the crystal is cooled. The power density levels that will be produced by insertion devices at the third-generation sources will be as much as a factor of 100 higher still. One method of restoring ideal x-ray diffraction behavior, while coping with high power levels, involves adaptive compensation of the induced thermal strain field. The design and performance, using the X25 hybrid wiggler beam line at the National Synchrotron Light Source (NSLS), of a silicon crystal bender constructed for this purpose are described

  12. Adaptive radiation of multituberculate mammals before the extinction of dinosaurs.

    Science.gov (United States)

    Wilson, Gregory P; Evans, Alistair R; Corfe, Ian J; Smits, Peter D; Fortelius, Mikael; Jernvall, Jukka

    2012-03-14

    The Cretaceous-Paleogene mass extinction approximately 66 million years ago is conventionally thought to have been a turning point in mammalian evolution. Prior to that event and for the first two-thirds of their evolutionary history, mammals were mostly confined to roles as generalized, small-bodied, nocturnal insectivores, presumably under selection pressures from dinosaurs. Release from these pressures, by extinction of non-avian dinosaurs at the Cretaceous-Paleogene boundary, triggered ecological diversification of mammals. Although recent individual fossil discoveries have shown that some mammalian lineages diversified ecologically during the Mesozoic era, comprehensive ecological analyses of mammalian groups crossing the Cretaceous-Paleogene boundary are lacking. Such analyses are needed because diversification analyses of living taxa allow only indirect inferences of past ecosystems. Here we show that in arguably the most evolutionarily successful clade of Mesozoic mammals, the Multituberculata, an adaptive radiation began at least 20 million years before the extinction of non-avian dinosaurs and continued across the Cretaceous-Paleogene boundary. Disparity in dental complexity, which relates to the range of diets, rose sharply in step with generic richness and disparity in body size. Moreover, maximum dental complexity and body size demonstrate an adaptive shift towards increased herbivory. This dietary expansion tracked the ecological rise of angiosperms and suggests that the resources that were available to multituberculates were relatively unaffected by the Cretaceous-Paleogene mass extinction. Taken together, our results indicate that mammals were able to take advantage of new ecological opportunities in the Mesozoic and that at least some of these opportunities persisted through the Cretaceous-Paleogene mass extinction. Similar broad-scale ecomorphological inventories of other radiations may help to constrain the possible causes of mass extinctions.

  13. From dinosaurs to modern bird diversity: extending the time scale of adaptive radiation.

    Science.gov (United States)

    Moen, Daniel; Morlon, Hélène

    2014-05-01

    What explains why some groups of organisms, like birds, are so species rich? And what explains their extraordinary ecological diversity, ranging from large, flightless birds to small migratory species that fly thousand of kilometers every year? These and similar questions have spurred great interest in adaptive radiation, the diversification of ecological traits in a rapidly speciating group of organisms. Although the initial formulation of modern concepts of adaptive radiation arose from consideration of the fossil record, rigorous attempts to identify adaptive radiation in the fossil record are still uncommon. Moreover, most studies of adaptive radiation concern groups that are less than 50 million years old. Thus, it is unclear how important adaptive radiation is over temporal scales that span much larger portions of the history of life. In this issue, Benson et al. test the idea of a "deep-time" adaptive radiation in dinosaurs, compiling and using one of the most comprehensive phylogenetic and body-size datasets for fossils. Using recent phylogenetic statistical methods, they find that in most clades of dinosaurs there is a strong signal of an "early burst" in body-size evolution, a predicted pattern of adaptive radiation in which rapid trait evolution happens early in a group's history and then slows down. They also find that body-size evolution did not slow down in the lineage leading to birds, hinting at why birds survived to the present day and diversified. This paper represents one of the most convincing attempts at understanding deep-time adaptive radiations.

  14. Optimization of adaptive radiation therapy in cervical cancer: Solutions for photon and proton therapy

    NARCIS (Netherlands)

    van de Schoot, A.J.A.J.

    2016-01-01

    In cervical cancer radiation therapy, an adaptive strategy is required to compensate for interfraction anatomical variations in order to achieve adequate dose delivery. In this thesis, we have aimed at optimizing adaptive radiation therapy in cervical cancer to improve treatment efficiency and

  15. Auto-propagation of contours for adaptive prostate radiation therapy

    International Nuclear Information System (INIS)

    Chao Ming; Xie Yaoqin; Xing Lei

    2008-01-01

    The purpose of this work is to develop an effective technique to automatically propagate contours from planning CT to cone beam CT (CBCT) to facilitate CBCT-guided prostate adaptive radiation therapy. Different from other disease sites, such as the lungs, the contour mapping here is complicated by two factors: (i) the physical one-to-one correspondence may not exist due to the insertion or removal of some image contents within the region of interest (ROI); and (ii) reduced contrast to noise ratio of the CBCT images due to increased scatter. To overcome these issues, we investigate a strategy of excluding the regions with variable contents by a careful design of a narrow shell signifying the contour of an ROI. For rectum, for example, a narrow shell with the delineated contours as its interior surface was constructed to avoid the adverse influence of the day-to-day content change inside the rectum on the contour mapping. The corresponding contours in the CBCT were found by warping the narrow shell through the use of BSpline deformable model. Both digital phantom experiments and clinical case testing were carried out to validate the proposed ROI mapping method. It was found that the approach was able to reliably warp the constructed narrow band with an accuracy better than 1.3 mm. For all five clinical cases enrolled in this study, the method yielded satisfactory results even when there were significant rectal content changes between the planning CT and CBCT scans. The overlapped area of the auto-mapped contours over 90% to the manually drawn contours is readily achievable. The proposed approach permits us to take advantage of the regional calculation algorithm yet avoiding the nuisance of rectum/bladder filling and provide a useful tool for adaptive radiotherapy of prostate in the future

  16. Auto-propagation of contours for adaptive prostate radiation therapy

    Science.gov (United States)

    Chao, Ming; Xie, Yaoqin; Xing, Lei

    2008-09-01

    The purpose of this work is to develop an effective technique to automatically propagate contours from planning CT to cone beam CT (CBCT) to facilitate CBCT-guided prostate adaptive radiation therapy. Different from other disease sites, such as the lungs, the contour mapping here is complicated by two factors: (i) the physical one-to-one correspondence may not exist due to the insertion or removal of some image contents within the region of interest (ROI); and (ii) reduced contrast to noise ratio of the CBCT images due to increased scatter. To overcome these issues, we investigate a strategy of excluding the regions with variable contents by a careful design of a narrow shell signifying the contour of an ROI. For rectum, for example, a narrow shell with the delineated contours as its interior surface was constructed to avoid the adverse influence of the day-to-day content change inside the rectum on the contour mapping. The corresponding contours in the CBCT were found by warping the narrow shell through the use of BSpline deformable model. Both digital phantom experiments and clinical case testing were carried out to validate the proposed ROI mapping method. It was found that the approach was able to reliably warp the constructed narrow band with an accuracy better than 1.3 mm. For all five clinical cases enrolled in this study, the method yielded satisfactory results even when there were significant rectal content changes between the planning CT and CBCT scans. The overlapped area of the auto-mapped contours over 90% to the manually drawn contours is readily achievable. The proposed approach permits us to take advantage of the regional calculation algorithm yet avoiding the nuisance of rectum/bladder filling and provide a useful tool for adaptive radiotherapy of prostate in the future.

  17. Adaptive introgression from distant Caribbean islands contributed to the diversification of a microendemic adaptive radiation of trophic specialist pupfishes.

    Directory of Open Access Journals (Sweden)

    Emilie J Richards

    2017-08-01

    Full Text Available Rapid diversification often involves complex histories of gene flow that leave variable and conflicting signatures of evolutionary relatedness across the genome. Identifying the extent and source of variation in these evolutionary relationships can provide insight into the evolutionary mechanisms involved in rapid radiations. Here we compare the discordant evolutionary relationships associated with species phenotypes across 42 whole genomes from a sympatric adaptive radiation of Cyprinodon pupfishes endemic to San Salvador Island, Bahamas and several outgroup pupfish species in order to understand the rarity of these trophic specialists within the larger radiation of Cyprinodon. 82% of the genome depicts close evolutionary relationships among the San Salvador Island species reflecting their geographic proximity, but the vast majority of variants fixed between specialist species lie in regions with discordant topologies. Top candidate adaptive introgression regions include signatures of selective sweeps and adaptive introgression of genetic variation from a single population in the northwestern Bahamas into each of the specialist species. Hard selective sweeps of genetic variation on San Salvador Island contributed 5 times more to speciation of trophic specialists than adaptive introgression of Caribbean genetic variation; however, four of the 11 introgressed regions came from a single distant island and were associated with the primary axis of oral jaw divergence within the radiation. For example, standing variation in a proto-oncogene (ski known to have effects on jaw size introgressed into one San Salvador Island specialist from an island 300 km away approximately 10 kya. The complex emerging picture of the origins of adaptive radiation on San Salvador Island indicates that multiple sources of genetic variation contributed to the adaptive phenotypes of novel trophic specialists on the island. Our findings suggest that a suite of factors

  18. Radiation adaptive response for the growth of cultured glial cells

    International Nuclear Information System (INIS)

    Suzuki, S.; Miura, Y.; Kano, M.; Toda, T.; Urano, S.

    2003-01-01

    Full text: To examine the molecular mechanism of radiation adaptive response (RAR) for the growth of cultured glial cells and to investigate the influence of aging on the response, glial cells were cultured from young and aged rats (1 month and 24 months old). RAR for the growth of glial cells conditioned with a low dose of X-rays and subsequently exposed to a high dose of X-rays was examined for cell number and BrdU incorporation. Involvement of the subcellular signaling pathway factors in RAR was investigated using their inhibitors, activators and mutated glial cells. RAR was observed in cells cultured from young rats, but was not in cells from aged rats. The inhibitors of protein kinase C (PKC) and DNA-dependent protein kinase (DNA-PK) or phosphatidylinositol 3-kinase (PI3K) suppressed RAR. The activators of PKC instead of low dose irradiation also caused RAR. Moreover, glial cells cultured from severe combined immunodeficiency (scid) mice (CB-17 scid) and ataxia-telangiectasia (AT) cells from AT patients showed no RAR. These results indicated that PKC, ATM, DNAPK and/or PI3K were involved in RAR for growth and BrdU incorporation of cultured glial cells and RAR decreased with aging. Proteomics data of glial cells exposed to severe stress of H 2 O 2 or X-rays also will be presented in the conference since little or no difference has not been observed with slight stress yet

  19. Does occupational exposure to ionizing radiation induce adaptation

    International Nuclear Information System (INIS)

    Djurovic, B.; Selakovic, V.; Radjen, S.; Radakovic, S.; Spasic-Jokic, V.

    2008-01-01

    Full text: Even the most of personnel occupationally exposed (OE) to ionizing radiation (IR) is exposed to very low doses (LD), some harmful effects can be noticed. IR can affect the cell structure in two ways: directly and indirectly-inducing radiolysis of water and production of reactive oxygen species (ROS) similar to endogenously induced. In the low- LET exposure almost 70 % of absorbed energy is spent for ROS production. Over-production of ROS can cause oxidative stress. DNA is the main target of induced ROS. It is also experimentally showed that many important cell protective mechanisms, such is adaptation, are dependent of ROS concentration produced by low doses. The aim of this paper is to investigate if occupational exposure to LD induce over-production of ROS, and influence the activity of protective enzymes and radiosensitivity as well as induce adaptation. Our subjects were medical workers occupationally exposed to IR (44) and not-exposed (33), matched in gender, age, habits-dietary, alcohol consumption, smoking. Occupational exposure was calculated on the basis of individual TL-dose records. Besides the standard medical examination, micronucleus test, superoxide production and lipid peroxidation index, expressed as malonaldehyde (MDA) production, were performed by standard procedures as well as measurements of activity of the superoxide dismutase (SOD) and glutathione (GSH). Half of each sample were put in a sterile plastic test-tube placed in a plexiglas container 15 x 15 cm, and irradiated by 60 Co source of γ-ray at room temperature. Employed radiation dose was 2 Gy, dose-rate 0.45 Gy/min and distance from the source 74 cm. All blood samples were frozen at -70 C degrees, and kept till analyses which were performed at the same time. Our results confirm: significantly higher incidence of micronuclei in OE (.31±10 vs 17±8, p=0.00) with significant increase after irradiation in each group and lack of differences in radiosensitivity between groups

  20. Adaptive Multichannel Radiation Sensors for Plant Parameter Monitoring

    Science.gov (United States)

    Mollenhauer, Hannes; Remmler, Paul; Schuhmann, Gudrun; Lausch, Angela; Merbach, Ines; Assing, Martin; Mollenhauer, Olaf; Dietrich, Peter; Bumberger, Jan

    2016-04-01

    Nutrients such as nitrogen are playing a key role in the plant life cycle. They are much needed for chlorophyll production and other plant cell components. Therefore, the crop yield is strongly affected by plant nutrient status. Due to the spatial and temporal variability of soil characteristics or swaying agricultural inputs the plant development varies within a field. Thus, the determination of these fluctuations in the plant development is valuable for a detection of stress conditions and optimization of fertilisation due to its high environmental and economic impact. Plant parameters play crucial roles in plant growth estimation and prediction since they are used as indicators of plant performance. Especially indices derived out of remote sensing techniques provide quantitative information about agricultural crops instantaneously, and above all, non-destructively. Due to the specific absorption of certain plant pigments, a characteristic spectral signature can be seen in the visible and IR part of the electromagnetic spectrum, known as narrow-band peaks. In an analogous manner, the presence and concentration of different nutrients cause a characteristic spectral signature. To this end, an adequate remote sensing monitoring concept is needed, considering heterogeneity and dynamic of the plant population and economical aspects. This work will present the development and field investigations of an inexpensive multichannel radiation sensor to observe the incoming and reflected specific parts or rather distinct wavelengths of the solar light spectrum on the crop and facilitate the determination of different plant indices. Based on the selected sensor wavelengths, the sensing device allows the detection of specific parameters, e.g. plant vitality, chlorophyll content or nitrogen content. Besides the improvement of the sensor characteristic, the simple wavelength adaption, and the price-performance ratio, the achievement of appropriate energy efficiency as well as a

  1. Understanding the role of p53 in adaptive response to radiation-induced germline mutations

    International Nuclear Information System (INIS)

    Langlois, N.L.; Quinn, J.S.; Somers, C.M.; Boreham, D.R.; Mitchel, R.E.J.

    2003-01-01

    Full text: Radiation-induced adaptive response is now a widely studied area of radiation biology. Studies have demonstrated reduced levels of radiation-induced biological damage when an 'adaptive dose' is given before a higher 'challenge dose' compared to when the challenge dose is given alone. It has been shown in some systems to be a result of inducible cellular repair systems. The adaptive response has been clearly demonstrated in many model systems, however its impact on heritable effects in the mammalian germline has never been studied. Expanded Simple Tandem Repeat (ESTR) loci have been used as markers demonstrating that induced heritable mutations in mice follow a dose-response relationship. Recent data in our laboratory show preliminary evidence of radiation-induced adaptive response suppressing germline mutations at ESTR loci in wild type mice. The frequency of heritable mutations was significantly reduced when a priming dose of 0.1 Gy was given 24 hours prior to a 1 Gy acute challenging dose. We are now conducting a follow-up study to attempt to understand the mechanism of this adaptive response. P53 is known to play a significant role in governing apoptosis, DNA repair and cancer induction. In order to determine what function p53 has in the adaptive response for heritable mutations, we have mated radiation treated Trp53+/- male mice (C57Bl) to untreated, normal females (C57Bl). Using DNA fingerprinting, we are investigating the rate of inherited radiation-induced mutations on pre- and post-meiotic radiation-treated gametocytes by examining mutation frequencies in offspring DNA. If p53 is integral in the mechanism of adaptive response, we should not see an adaptive response in radiation-induced heritable mutations in these mice. This research is significant in that it will provide insight to understanding the mechanism behind radiation-induced adaptive response in the mammalian germline

  2. Radiation-induced adaptive response in human lymphoblast

    International Nuclear Information System (INIS)

    Yatagai, Fumio; Sugasawa, Kaoru

    2009-01-01

    Described are the genetic analysis of variant strains obtained by the optimal condition for radiation-induced adaptive response (AR), and molecular elucidation of the suppression of concomitant mutation. The TK6 cells (heterozygous thymidine kinase, +/-) were used for detection of mutation by loss of heterozygosity (LOH). The optimal conditions for reducing the mutation by subsequent irradiation (SI) to its rate of about 60% (vs control 100%, no PI) were found to be 5 cGy of pre-irradiation (PI) of X-ray and 2 Gy of SI with the interval of 6 hr, where mutated cells were of non-LOH type in around 25% and homo-LOH type by homologous recombination (HR) in 60%. By cDNA sequencing, the former cells having changed bases were found to be in variant strain ratio of 1/8 vs control 7/18, suggesting that the mutation was decreased mainly by suppression of base change. Expression of XPC protein, an important component for recognition of the base damage in global genome nucleotide excision repair, was studied by Western blotting as the possible mechanism of suppressing the mutation, which revealed different time dynamics of the protein in cells with PI+SI and SI alone (control). To see the effect of PI on the double strand break (DSB) repair, cells with PI were infected with restriction enzyme I-SceI vector to yield DSB instead of SI, which revealed more efficient repair (70% increase) by HR than control, without significant difference in non-homologous end-joining repair. Micro-array analysis to study the gene expression in the present experimental conditions for AR is in progress. The TK6 cells used here were thought useful for additional studies of the mechanism of AR as mutation by direct or indirect irradiation can be tested. (K.T.)

  3. The Adaptive Radiation of Cichlid Fish in Lake Tanganyika: A Morphological Perspective

    Directory of Open Access Journals (Sweden)

    Tetsumi Takahashi

    2011-01-01

    Full Text Available Lake Tanganyika is the oldest of the Great Ancient Lakes in the East Africa. This lake harbours about 250 species of cichlid fish, which are highly diverse in terms of morphology, behaviour, and ecology. Lake Tanganyika's cichlid diversity has evolved through explosive speciation and is treated as a textbook example of adaptive radiation, the rapid differentiation of a single ancestor into an array of species that differ in traits used to exploit their environments and resources. To elucidate the processes and mechanisms underlying the rapid speciation and adaptive radiation of Lake Tanganyika's cichlid species assemblage it is important to integrate evidence from several lines of research. Great efforts have been, are, and certainly will be taken to solve the mystery of how so many cichlid species evolved in so little time. In the present review, we summarize morphological studies that relate to the adaptive radiation of Lake Tanganyika's cichlids and highlight their importance for understanding the process of adaptive radiation.

  4. On-line Adaptive Radiation Treatment of Prostate Cancer

    National Research Council Canada - National Science Library

    Zhang, Tiezhi

    2008-01-01

    .... The specific aims of this project are to develop the key technical components for online adaptive treatment, which include parallel deformable image registration algorithm, parallel dose calculation...

  5. From dinosaurs to modern bird diversity: extending the time scale of adaptive radiation.

    Directory of Open Access Journals (Sweden)

    Daniel Moen

    2014-05-01

    Full Text Available What explains why some groups of organisms, like birds, are so species rich? And what explains their extraordinary ecological diversity, ranging from large, flightless birds to small migratory species that fly thousand of kilometers every year? These and similar questions have spurred great interest in adaptive radiation, the diversification of ecological traits in a rapidly speciating group of organisms. Although the initial formulation of modern concepts of adaptive radiation arose from consideration of the fossil record, rigorous attempts to identify adaptive radiation in the fossil record are still uncommon. Moreover, most studies of adaptive radiation concern groups that are less than 50 million years old. Thus, it is unclear how important adaptive radiation is over temporal scales that span much larger portions of the history of life. In this issue, Benson et al. test the idea of a "deep-time" adaptive radiation in dinosaurs, compiling and using one of the most comprehensive phylogenetic and body-size datasets for fossils. Using recent phylogenetic statistical methods, they find that in most clades of dinosaurs there is a strong signal of an "early burst" in body-size evolution, a predicted pattern of adaptive radiation in which rapid trait evolution happens early in a group's history and then slows down. They also find that body-size evolution did not slow down in the lineage leading to birds, hinting at why birds survived to the present day and diversified. This paper represents one of the most convincing attempts at understanding deep-time adaptive radiations.

  6. Adaptive response and split-dose effect of radiation on the survival ...

    Indian Academy of Sciences (India)

    Unknown

    The findings have been discussed from a mechanistic point of view. The possible biological implications, potential medical benefits, uncertainties and controversies related to adaptive response have also been addressed. [Tiku A B and Kale R K 2004 Adaptive response and split-dose effect of radiation on the survival of ...

  7. Adaptive radiation image enhancement based on different image quality evaluation standards

    International Nuclear Information System (INIS)

    Guo Xiaojing; Wu Zhifang

    2012-01-01

    Genetic algorithm based on incomplete Beta function was realized, and adaptive gray transform based on the said genetic algorithm was implemented, based as such, three image quality evaluation standards were applied in the adaptive gray transform of radiation images, and effects of processing time, stability, generation number and so on of the three standards were compared. The better algorithm scheme was applied in image processing module of container DR/CT inspection system to obtain effective adaptive image enhancement. (authors)

  8. Possible human impacts on adaptive radiation: beak size bimodality in Darwin's finches

    OpenAIRE

    Hendry, Andrew P; Grant, Peter R; Rosemary Grant, B; Ford, Hugh A; Brewer, Mark J; Podos, Jeffrey

    2006-01-01

    Adaptive radiation is facilitated by a rugged adaptive landscape, where fitness peaks correspond to trait values that enhance the use of distinct resources. Different species are thought to occupy the different peaks, with hybrids falling into low-fitness valleys between them. We hypothesize that human activities can smooth adaptive landscapes, increase hybrid fitness and hamper evolutionary diversification. We investigated this possibility by analysing beak size data for 1755 Geospiza fortis...

  9. A goal-based angular adaptivity method for thermal radiation modelling in non grey media

    Science.gov (United States)

    Soucasse, Laurent; Dargaville, Steven; Buchan, Andrew G.; Pain, Christopher C.

    2017-10-01

    This paper investigates for the first time a goal-based angular adaptivity method for thermal radiation transport, suitable for non grey media when the radiation field is coupled with an unsteady flow field through an energy balance. Anisotropic angular adaptivity is achieved by using a Haar wavelet finite element expansion that forms a hierarchical angular basis with compact support and does not require any angular interpolation in space. The novelty of this work lies in (1) the definition of a target functional to compute the goal-based error measure equal to the radiative source term of the energy balance, which is the quantity of interest in the context of coupled flow-radiation calculations; (2) the use of different optimal angular resolutions for each absorption coefficient class, built from a global model of the radiative properties of the medium. The accuracy and efficiency of the goal-based angular adaptivity method is assessed in a coupled flow-radiation problem relevant for air pollution modelling in street canyons. Compared to a uniform Haar wavelet expansion, the adapted resolution uses 5 times fewer angular basis functions and is 6.5 times quicker, given the same accuracy in the radiative source term.

  10. Plasma ICR heating antennas: adaptation, radiated field structure, coupling

    International Nuclear Information System (INIS)

    Pegourie, B.

    1982-01-01

    The transmission line theory has been used to find the antenna adapattion improvement possibilities, so as to optimize the power transfer from generator to plasma. ICR heating antennas are described, radiated magnetic field is measured, and superstructures (diaphragms and electrostatic screen) is studied from a mock-up and a numerical model. Results about antenna radiation and electric property modifications due to superstructures, without plasma, are presented. At last, TFR antenna coupling properties, in terms of frequency, electromagnetic wave and plasma conditions, are studied. In the whole work, we tried to define, when possible the construction criteria fitted to cyclotron heating in the big tokamak experiments under construction [fr

  11. Determining appropriate timing of adaptive radiation therapy for nasopharyngeal carcinoma during intensity-modulated radiation therapy

    International Nuclear Information System (INIS)

    Huang, Huixian; Lu, Heming; Feng, Guosheng; Jiang, Hailan; Chen, Jiaxin; Cheng, Jinjian; Pang, Qiang; Lu, Zhiping; Gu, Junzhao; Peng, Luxing; Deng, Shan; Mo, Ying; Wu, Danling; Wei, Yinglin

    2015-01-01

    To determine appropriate timing of an adaptive radiation therapy (ART) replan by evaluating anatomic and dosimetric changes of target volumes and organs at risk (OARs) during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC). Nineteen NPC patients were recruited. Each patient had repeat computed tomography (CT) scans after each five fractions and at treatment completion. Automatic re-contouring the targets and OARs by using deformable registration algorithm was conducted through CT-CT fusion. Anatomic changes were assessed by comparing the initial CT and repeated CT. Hybrid plans with re-contouring were generated and the dose-volume histograms (DVH) of the hybrid plan and the original plan were compared. Progressive volume reductions in gross target volume for primary disease (GTVnx), gross target volume for involved lymph nodes (GTVnd), and parotids were observed over time. Comparing with the original plan, each hybrid plan had no significant difference in homogeneity index (HI) for all the targets. Some parameters for planning target volumes for primary disease and high-risk clinical target volume (PTVnx and PTV1, respectively) improved significantly, notably starting from the 10th fraction. These parameters included mean dose (Dmean), dose to 95 % of the volume (D95), percentage of the volume receiving 95 % of the prescription dose (V95), and conformity index (CI) for PTVnx, and Dmean, D95, and CI for PTV1. The dosimetric parameters for PTVnd remained the same in general except for D95 and V95 which had significant improvement at specific time points; whereas for PTV2, similar trend of dosimetric changes was also observed. Dose to some OARs increased significantly at some time points. There were significant anatomic and dosimetric changes in the targets and OARs. The target dose coverage in the hybrid plans did not get worse, but overdose occurred in some critical structures. Significant dosimetric changes should be considered as a

  12. Adaptive Divergence in Experimental Populations of Pseudomonas fluorescens. IV. Genetic Constraints Guide Evolutionary Trajectories in a Parallel Adaptive Radiation

    OpenAIRE

    McDonald, Michael J.; Gehrig, Stefanie M.; Meintjes, Peter L.; Zhang, Xue-Xian; Rainey, Paul B.

    2009-01-01

    The capacity for phenotypic evolution is dependent upon complex webs of functional interactions that connect genotype and phenotype. Wrinkly spreader (WS) genotypes arise repeatedly during the course of a model Pseudomonas adaptive radiation. Previous work showed that the evolution of WS variation was explained in part by spontaneous mutations in wspF, a component of the Wsp-signaling module, but also drew attention to the existence of unknown mutational causes. Here, we identify two new muta...

  13. Extremely low doses of X-radiation can induce adaptive responses in mouse prostate

    International Nuclear Information System (INIS)

    Day, T.K.; Zeng, G.; Hooker, A.M.; Turner, D.R.; Sykes, P.J.; Baht, M.

    2006-01-01

    Full text: The pKZl mouse chromosomal inversion assay is the only assay which has detected modulation of a mutagenic endpoint after single whole body X-irradiation with doses lower than 1 mGy. A non-linear dose response for chromosomal inversion has been observed between 1 jaGy and 10 mGy with doses between 5-10 uGy causing an induction in inversions and doses between 1-10 mGy causing a reduction below endogenous inversion frequency (Hooker et al, 2004. Radiat. Res. 162:447-52.) An adaptive response is a decreased biological effect induced by a priming radiation dose given prior to a challenge dose. Adaptive responses contradict the linear-no-threshold model of risk estimation. pKZl mice were exposed to priming radiation doses which by themselves either induced or reduced inversion frequency. Four hours later mice received a challenge dose of 1000 mGy. The inversion frequency was quantified in prostate three days later. We demonstrated that very low (10 mGy, 1 mGy and 10 )J,Gy) priming doses of X-radiation induced a chromosomal inversion adaptive response. These are the lowest X-radiation doses reported to induce an adaptive response for any endpoint. Reverse adaptive response experiments will also be discussed where the challenge dose studied was lower than the priming dose. Analysis of the distribution of inversions in 50 prostatic glands screened/animal suggested that there are two types of damage induced by the high challenge dose and only one of these types of damage is modified by the priming dose. Identification of the modifying factors involved in the adaptive response may provide candidates for radioprotection. This work was funded by the Low Dose Radiation Research Program, U.S. Department of Energy, grant no. DE-FG02-01ER63227 and DE-FG02-05ER64104

  14. Adaptation of vacuum-assisted mouthpiece head immobilization system for precision infant brain radiation therapy.

    Science.gov (United States)

    Wong, Kenneth; Cheng, Justine; Bowlin, Kristine; Olch, Arthur

    Our purpose was to describe an adaptation of a commercially available mouthpiece for vacuum-assisted mouthpiece immobilization for radiation therapy in infants. An infant diagnosed with a brain tumor required radiation therapy. After reviewing dental literature about obturators, we designed a modification for the smallest commercially available mouthpiece tray. The patient was simulated with the adapted mouthpiece tray. We achieved excellent immobilization and had small daily image guided treatment position shifts. Our patient tolerated treatment well without injury to oral cavity or mucosa. Head immobilization with a vacuum-assisted modified mouthpiece has not been described in infants. Our modification is a novel and safe and permits effective and accurate immobilization for infants for radiation therapy. New manufacturing technologies may allow creation of individualized mouthpieces. Copyright © 2016 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

  15. Genome hypermethylation in Pinus silvestris of Chernobyl - a mechanism for radiation adaptation?

    Energy Technology Data Exchange (ETDEWEB)

    Kovalchuk, Olga; Burke, Paula; Arkhipov, Andrey; Kuchma, Nikolaj; James, S. Jill; Kovalchuk, Igor; Pogribny, Igor

    2003-08-28

    Adaptation is a complex process by which populations of organisms respond to long-term environmental stresses by permanent genetic change. Here we present data from the natural 'open-field' radiation adaptation experiment after the Chernobyl accident and provide the first evidence of the involvement of epigenetic changes in adaptation of a eukaryote-Scots pine (Pinus silvestris), to chronic radiation exposure. We have evaluated global genome methylation of control and radiation-exposed pine trees using a method based on cleavage by a methylation-sensitive HpaII restriction endonuclease that leaves a 5' guanine overhang and subsequent single nucleotide extension with labeled [{sup 3}H] dCTP. We have found that genomic DNA of exposed pine trees was considerably hypermethylated. Moreover, hypermethylation appeared to be dependent upon the radiation dose absorbed by the trees. Such hypermethylation may be viewed as a defense strategy of plants that prevents genome instability and reshuffling of the hereditary material, allowing survival in an extreme environment. Further studies are clearly needed to analyze in detail the involvement of DNA methylation and other epigenetic mechanisms in the complex process of radiation stress and adaptive response.

  16. Diversification rates indicate an early role of adaptive radiations at the origin of modern echinoid fauna.

    Directory of Open Access Journals (Sweden)

    Simon Boivin

    Full Text Available Evolutionary radiations are fascinating phenomena corresponding to a dramatic diversification of taxa and a burst of cladogenesis over short periods of time. Most evolutionary radiations have long been regarded as adaptive but this has seldom been demonstrated with large-scale comparative datasets including fossil data. Originating in the Early Jurassic, irregular echinoids are emblematic of the spectacular diversification of mobile marine faunas during the Mesozoic Marine Revolution. They diversified as they colonized various habitats, and now constitute the main component of echinoid fauna in modern seas. The evolutionary radiation of irregular echinoids has long been considered as adaptive but this hypothesis has never been tested. In the present work we analyze the evolution of echinoid species richness and morphological disparity over 37 million years based on an extensive fossil dataset. Our results demonstrate that morphological and functional diversifications in certain clades of irregular echinoids were exceptionally high compared to other clades and that they were associated with the evolution of new modes of life and so can be defined as adaptive radiations. The role played by ecological opportunities in the diversification of these clades was critical, with the evolution of the infaunal mode of life promoting the adaptive radiation of irregular echinoids.

  17. Cranial shape evolution in adaptive radiations of birds: comparative morphometrics of Darwin's finches and Hawaiian honeycreepers

    Science.gov (United States)

    Tokita, Masayoshi; Yano, Wataru; James, Helen F.

    2017-01-01

    Adaptive radiation is the rapid evolution of morphologically and ecologically diverse species from a single ancestor. The two classic examples of adaptive radiation are Darwin's finches and the Hawaiian honeycreepers, which evolved remarkable levels of adaptive cranial morphological variation. To gain new insights into the nature of their diversification, we performed comparative three-dimensional geometric morphometric analyses based on X-ray microcomputed tomography (µCT) scanning of dried cranial skeletons. We show that cranial shapes in both Hawaiian honeycreepers and Coerebinae (Darwin's finches and their close relatives) are much more diverse than in their respective outgroups, but Hawaiian honeycreepers as a group display the highest diversity and disparity of all other bird groups studied. We also report a significant contribution of allometry to skull shape variation, and distinct patterns of evolutionary change in skull morphology in the two lineages of songbirds that underwent adaptive radiation on oceanic islands. These findings help to better understand the nature of adaptive radiations in general and provide a foundation for future investigations on the developmental and molecular mechanisms underlying diversification of these morphologically distinguished groups of birds. This article is part of the themed issue ‘Evo-devo in the genomics era, and the origins of morphological diversity’. PMID:27994122

  18. Cranial shape evolution in adaptive radiations of birds: comparative morphometrics of Darwin's finches and Hawaiian honeycreepers.

    Science.gov (United States)

    Tokita, Masayoshi; Yano, Wataru; James, Helen F; Abzhanov, Arhat

    2017-02-05

    Adaptive radiation is the rapid evolution of morphologically and ecologically diverse species from a single ancestor. The two classic examples of adaptive radiation are Darwin's finches and the Hawaiian honeycreepers, which evolved remarkable levels of adaptive cranial morphological variation. To gain new insights into the nature of their diversification, we performed comparative three-dimensional geometric morphometric analyses based on X-ray microcomputed tomography (µCT) scanning of dried cranial skeletons. We show that cranial shapes in both Hawaiian honeycreepers and Coerebinae (Darwin's finches and their close relatives) are much more diverse than in their respective outgroups, but Hawaiian honeycreepers as a group display the highest diversity and disparity of all other bird groups studied. We also report a significant contribution of allometry to skull shape variation, and distinct patterns of evolutionary change in skull morphology in the two lineages of songbirds that underwent adaptive radiation on oceanic islands. These findings help to better understand the nature of adaptive radiations in general and provide a foundation for future investigations on the developmental and molecular mechanisms underlying diversification of these morphologically distinguished groups of birds.This article is part of the themed issue 'Evo-devo in the genomics era, and the origins of morphological diversity'. © 2016 The Authors.

  19. Goal based mesh adaptivity for fixed source radiation transport calculations

    International Nuclear Information System (INIS)

    Baker, C.M.J.; Buchan, A.G.; Pain, C.C.; Tollit, B.S.; Goffin, M.A.; Merton, S.R.; Warner, P.

    2013-01-01

    Highlights: ► Derives an anisotropic goal based error measure for shielding problems. ► Reduces the error in the detector response by optimizing the finite element mesh. ► Anisotropic adaptivity captures material interfaces using fewer elements than AMR. ► A new residual based on the numerical scheme chosen forms the error measure. ► The error measure also combines the forward and adjoint metrics in a novel way. - Abstract: In this paper, the application of goal based error measures for anisotropic adaptivity applied to shielding problems in which a detector is present is explored. Goal based adaptivity is important when the response of a detector is required to ensure that dose limits are adhered to. To achieve this, a dual (adjoint) problem is solved which solves the neutron transport equation in terms of the response variables, in this case the detector response. The methods presented can be applied to general finite element solvers, however, the derivation of the residuals are dependent on the underlying finite element scheme which is also discussed in this paper. Once error metrics for the forward and adjoint solutions have been formed they are combined using a novel approach. The two metrics are combined by forming the minimum ellipsoid that covers both the error metrics rather than taking the maximum ellipsoid that is contained within the metrics. Another novel approach used within this paper is the construction of the residual. The residual, used to form the goal based error metrics, is calculated from the subgrid scale correction which is inherent in the underlying spatial discretisation employed

  20. Prolonged stress induces adaptation of drosophila population to ionizing radiation

    International Nuclear Information System (INIS)

    Mosse, I. B.; Glushkova, I. V.; Aksyutik, T. V.

    2003-01-01

    We studied natural populations of Drosophila melanogaster from radio-contaminated area (Vetka district of Gomel region with 24 Ci/km 2 of 137 Cs and 0.5 Cu/km 2 of 90 Sr) and from Berezynski Natural Reserve as a control area (region of Chernobyl catastrophe). Population samples were caught in 2000-2001 years. Natural insect populations from radio-contaminated areas are more resistant to additional irradiation than control populations. Keeping of natural populations under laboratory or vivarium conditions is a strong stress (limited space, overpopulation, other than in nature temperature and light conditions), which increases mutation process and induces unspecific adaptation. (authors)

  1. The possible role of chromatin conformation changes in adaptive responses to ionizing radiation

    International Nuclear Information System (INIS)

    Ekhtiar, A.; Ammer, A.; Jbawi, A.; Othman, A.

    2012-05-01

    Organisms are affected by different DNA damaging agents naturally present in the environment or released as a result of human activity. Many defense mechanisms have evolved in organisms to minimize genotoxic damage. One of them is induced radioresistance or adaptive response. The adaptive response could be considered as a nonspecific phenomenon in which exposure to minimal stress could result in increased resistance to higher levels of the same or to other types of stress some hours later. A better understanding of the molecular mechanism underlying the adaptive response may lead to an improvement of cancer treatment, risk assessment and risk management strategies, radiation protection. The aim of current study was to study the possible role of chromatin conformation changes induced by ionizing radiation on the adaptive responses in human lymphocyte. For this aim the chromatin conformation have been studied in human lymphocytes from three non-smoking and three smoking healthy volunteers prior, and after espouser to gamma radiation (adaptive dose 0.1 Gy, challenge dose 1.5 Gy and adaptive + dose challenge). Chromosomal aberrations and micronucleus have been used as end point to study radio cytotoxicity and adaptive response. Our results indicated individual differences in radio adaptive response and the level of this response was dependent of chromatin de condensation induced by a adaptive small dose.The results showed that different dose of gamma rays induce a chromatin de condensation in human lymphocyte. The maximum chromatin relaxation were record when lymphocyte exposed to adaptive dose (0.1 Gy.). Results also showed that Adaptive dose have affected on the induction of challenge dose (1.5 Gy) of chromosome aberration and micronucleus . The comparison of results of chromatin de condensation induction as measured by flow cytometry and cytogenetic damages measured by chromosomal aberrations or micronucleus, was showed a proportionality of adaptive response with

  2. Hierarchical Adaptive Solution of Radiation Transport Problems on Unstructured Grids

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Cassiano R. E de Oliveira

    2008-06-30

    Computational radiation transport has steadily gained acceptance in the last decade as a viable modeling tool due to the rapid advancements in computer software and hardware technologies. It can be applied for the analysis of a wide range of problems which arise in nuclear reactor physics, medical physics, atmospheric physics, astrophysics and other areas of engineering physics. However, radiation transport is an extremely chanllenging computational problem since the governing equation is seven-deimensional (3 in space, 2 in direction, 1 in energy, and 1 in time) with a high degree of coupleing betwen these variables. If not careful, this relatively large number of independent variables when discretized can potentially lead to sets of linear equations of intractable size. Though parallel computing has allowed the solution of very large problems, avaliable computational resources will always be finite due to the fact that every more sophisticated multiphysics models are being demanded by industry. There is thus the pressing requirement to optimize the discretizations so as to minimize the effort and maximize the accuracy.

  3. A quantitative formulation of the dynamic behaviour of adaptation processes to ionizing radiation

    International Nuclear Information System (INIS)

    Pfandler, S.

    1999-12-01

    The discovery of adaptation processes in cells (i.e., increased resistance to effects of a challenge dose administered after a lower adapting dose) has fuelled the debate on possible cellular processes relevant for low dose exposures. However, numerous experiments on radioadaptive response do not provide a clear picture of the nature of adaptive response and the conditions under which it occurs. This work proposes a model that succeeds in modelling data obtained from various experiments on radioadaptation. The model assumes impaired DNA integrity as triggering signal for induction of adaptation. Induction of adaptive response is seen as two-phase process. First, ionizing radiation induces radicals by water radiolysis which give rise to specific DNA lesions. On the other hand, these lesions must be perceived and, in a way, processed by the cell, thereby creating the final signal necessary for the comprehensive adaptive response. This processing occurs through some event in S-phase and can be halted by local conformational changes of chromatin induced by ionizing radiation. Thus, the model assumes two counteracting processes that have to be balanced for the triggering signal of adaptation to occur, each of them related to different target volumes. This work comprises mathematical treatment of radical formation, DNA lesion induction and inhibition of local initiation of replication which finally provides functions that quantify the reduction of double strand breaks introduced by challenge doses in adapted cells as compared to non-adapted cells. Non-linear regression analyses based upon data from experiments on radioadaptation yield regression curves which describe existing data satisfactorily. Thus, it corroborates the existence of adaptive response as, in principle, universal feature of cells and specifies conditions which favor development of radioadaptation. (author)

  4. Adaptive response and split-dose effect of radiation on the survival ...

    Indian Academy of Sciences (India)

    Unknown

    Although the importance of radiation-induced adaptive response has been recognized in human health, risk assessment and clinical application, the phenomenon has not been understood well in terms of survival of ani- mals. To examine this aspect Swiss albino mice were irradiated with different doses (2–10 Gy) at 0⋅015 ...

  5. Disentangling adaptive evolutionary radiations and the role of diet in promoting diversification on islands

    Science.gov (United States)

    DeMiguel, Daniel

    2016-01-01

    Although the initial formulation of modern concepts of adaptive radiation arose from consideration of the fossil data, rigorous attempts to identify this phenomenon in the fossil record are largely uncommon. Here I focus on direct evidence of the diet (through tooth-wear patterns) and ecologically-relevant traits of one of the most renowned fossil vertebrates-the Miocene ruminant Hoplitomeryx from the island of Gargano-to deepen our understanding of the most likely causal forces under which adaptive radiations emerge on islands. Results show how accelerated accumulation of species and early-bursts of ecological diversification occur after invading an island, and provide insights on the interplay between diet and demographic (population-density), ecological (competition/food requirements) and abiotic (climate-instability) factors, identified as drivers of adaptive diversification. A pronounced event of overpopulation and a phase of aridity determined most of the rate and magnitude of radiation, and pushed species to expand diets from soft-leafy foods to tougher-harder items. Unexpectedly, results show that herbivorous mammals are restricted to browsing habits on small-islands, even if bursts of ecological diversification and dietary divergence occur. This study deepens our understanding of the mechanisms promoting adaptive radiations, and forces us to reevaluate the role of diet in the origins and evolution of islands mammals. PMID:27405690

  6. Adaptive response and split-dose effect of radiation on the survival ...

    Indian Academy of Sciences (India)

    Although the importance of radiation-induced adaptive response has been recognized in human health, risk assessment and clinical application, the phenomenon has not been understood well in terms of survival of animals. To examine this aspect Swiss albino mice were irradiated with different doses (2–10 Gy) at 0.015 ...

  7. [Benefits of breathing-adapted radiation therapy for breast cancer].

    Science.gov (United States)

    Vourch, S; Miglierini, P; Miranda, O; Malhaire, J-P; Boussion, N; Pradier, O; Schick, U

    2016-02-01

    The purpose of this study was to compare free-breathing radiotherapy, end-expiration gating and end-inspiration gating for left breast cancer, with respect to the target volume coverage and dose to organs at risk. Sixteen patients underwent 3D and 4D simulation CT. For each patient, five dosimetric plans were compared: free breathing, end-inspiration gating, end-expiration gating, and two optimised plans with a 3mm reduction of the posterior field edge to create optimised end-inspiration and end-expiration plans. Dose-volume parameters, including planning target volume coverage and dose to lung, heart and left anterior descending coronary artery were analysed. Planning target volume coverage was adequate and similar in the five dosimetric plans (P=0.49). Significant advantage was found for end-inspiration gating in sparing the ipsilateral lung, heart and left anterior descending coronary artery compared to free-breathing 3D radiotherapy. Optimised end-inspiration was even more favourable than end-inspiration gating (Pradiation therapy allowed for dose reduction to organs at risk (left lung, heart and left anterior descending coronary artery), while keeping the same planning target volume coverage. Therefore it can be considered as an interesting option for left breast cancer radiation treatment. Copyright © 2015 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

  8. Adaptive radiation of island plants: Evidence from Aeonium (Crassulaceae) of the Canary Islands

    DEFF Research Database (Denmark)

    Jorgensen, T.H.; Olesen, J.M.

    2001-01-01

    The presence of diverse and species-rich plant lineages on oceanic islands is most often associated with adaptive radiation. Here we discuss the possible adaptive significance of some of the most prominent traits in island plants, including woodiness, monocarpy and sexual dimorphisms. Indirect...... evidence that such traits have been acquired through convergent evolution on islands comes from molecular phylogenies; however, direct evidence of their selective value rarely is obtained. The importance of hybridization in the evolution of island plants is also considered as part of a more general...... discussion of the mechanisms governing radiations on islands. Most examples are from the Hawaiian and Canarian floras, and in particular from studies on the morphological, ecological and molecular diversification of the genus Aeonium, the largest plant radiation of the Canarian Islands....

  9. Adaptive response in frogs chronically exposed to low doses of ionizing radiation in the environment

    International Nuclear Information System (INIS)

    Audette-Stuart, M.; Kim, S.B.; McMullin, D.; Festarini, A.; Yankovich, T.L.; Carr, J.; Mulpuru, S.

    2011-01-01

    Using the micronucleus assay, decreased levels of DNA damage were found after high dose ionizing radiation exposure of liver cells taken from frogs inhabiting a natural environment with above-background levels of ionizing radiation, compared to cells taken from frogs inhabiting background areas. The data obtained from a small number of animals suggest that stress present in the above-background environment could induce an adaptive response to ionizing radiation. This study did not reveal harmful effects of exposure to low levels of radioactivity. On the contrary, stress present in the above-background area may serve to enhance cellular defense mechanisms. - Highlights: → Frogs were collected from background and higher tritium level habitats. → The micronucleus assay was conducted on liver cells obtained from the frogs. → No detrimental effects were noted in frogs exposed to elevated tritium. → Adaptive responses were observed in frogs exposed to elevated tritium.

  10. Adaptive response in frogs chronically exposed to low doses of ionizing radiation in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Audette-Stuart, M., E-mail: stuartm@aecl.ca [Environmental Technologies Branch, Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, Ontario, K0J 1P0 (Canada); Kim, S.B.; McMullin, D.; Festarini, A.; Yankovich, T.L.; Carr, J.; Mulpuru, S. [Environmental Technologies Branch, Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, Ontario, K0J 1P0 (Canada)

    2011-06-15

    Using the micronucleus assay, decreased levels of DNA damage were found after high dose ionizing radiation exposure of liver cells taken from frogs inhabiting a natural environment with above-background levels of ionizing radiation, compared to cells taken from frogs inhabiting background areas. The data obtained from a small number of animals suggest that stress present in the above-background environment could induce an adaptive response to ionizing radiation. This study did not reveal harmful effects of exposure to low levels of radioactivity. On the contrary, stress present in the above-background area may serve to enhance cellular defense mechanisms. - Highlights: > Frogs were collected from background and higher tritium level habitats. > The micronucleus assay was conducted on liver cells obtained from the frogs. > No detrimental effects were noted in frogs exposed to elevated tritium. > Adaptive responses were observed in frogs exposed to elevated tritium.

  11. Regulation Of Nf=kb And Mnsod In Low Dose Radiation Induced Adaptive Protection Of Mouse And Human Skin Cells

    Energy Technology Data Exchange (ETDEWEB)

    Jian Li

    2012-11-07

    A sampling of publications resulting from this grant is provided. One is on the subject of NF-κB-Mediated HER2 Overexpression in Radiation-Adaptive Resistance. Another is on NF-κB-mediated adaptive resistance to ionizing radiation.

  12. Benefits of adaptive radiation therapy in lung cancer as a function of replanning frequency.

    Science.gov (United States)

    Dial, Christian; Weiss, Elisabeth; Siebers, Jeffrey V; Hugo, Geoffrey D

    2016-04-01

    To quantify the potential benefit associated with daily replanning in lung cancer in terms of normal tissue dose sparing and to characterize the tradeoff between adaptive benefit and replanning frequency. A set of synthetic images and contours, derived from weekly active breathing control images of 12 patients who underwent radiation therapy treatment for nonsmall cell lung cancer, is generated for each fraction of treatment using principal component analysis in a way that preserves temporal anatomical trends (e.g., tumor regression). Daily synthetic images and contours are used to simulate four different treatment scenarios: (1) a "no-adapt" scenario that simulates delivery of an initial plan throughout treatment, (2) a "midadapt" scenario that implements a single replan for fraction 18, (3) a "weekly adapt" scenario that simulates weekly adaptations, and (4) a "full-adapt" scenario that simulates daily replanning. An initial intensity modulated radiation therapy plan is created for each patient and replanning is carried out in an automated fashion by reoptimizing beam apertures and weights. Dose is calculated on each image and accumulated to the first in the series using deformable mappings utilized in synthetic image creation for comparison between simulated treatments. Target coverage was maintained and cord tolerance was not exceeded for any of the adaptive simulations. Average reductions in mean lung dose (MLD) and volume of lung receiving 20 Gy or more (V20lung) were 65 ± 49 cGy (p = 0.000 01) and 1.1% ± 1.2% (p = 0.0006), respectively, for all patients. The largest reduction in MLD for a single patient was 162 cGy, which allowed an isotoxic escalation of the target dose of 1668 cGy. Average reductions in cord max dose, mean esophageal dose (MED), dose received by 66% of the heart (D66heart), and dose received by 33% of the heart (D33heart), were 158 ± 280, 117 ± 121, 37 ± 77, and 99 ± 120 cGy, respectively. Average incremental reductions in MLD for

  13. An adaptive radiation model for the origin of new genefunctions

    Energy Technology Data Exchange (ETDEWEB)

    Francino, M. Pilar

    2004-10-18

    The evolution of new gene functions is one of the keys to evolutionary innovation. Most novel functions result from gene duplication followed by divergence. However, the models hitherto proposed to account for this process are not fully satisfactory. The classic model of neofunctionalization holds that the two paralogous gene copies resulting from a duplication are functionally redundant, such that one of them can evolve under no functional constraints and occasionally acquire a new function. This model lacks a convincing mechanism for the new gene copies to increase in frequency in the population and survive the mutational load expected to accumulate under neutrality, before the acquisition of the rare beneficial mutations that would confer new functionality. The subfunctionalization model has been proposed as an alternative way to generate genes with altered functions. This model also assumes that new paralogous gene copies are functionally redundant and therefore neutral, but it predicts that relaxed selection will affect both gene copies such that some of the capabilities of the parent gene will disappear in one of the copies and be retained in the other. Thus, the functions originally present in a single gene will be partitioned between the two descendant copies. However, although this model can explain increases in gene number, it does not really address the main evolutionary question, which is the development of new biochemical capabilities. Recently, a new concept has been introduced into the gene evolution literature which is most likely to help solve this dilemma. The key point is to allow for a period of natural selection for the duplication per se, before new function evolves, rather than considering gene duplication to be neutral as in the previous models. Here, I suggest a new model that draws on the advantage of postulating selection for gene duplication, and proposes that bursts of adaptive gene amplification in response to specific selection

  14. "Intelligent Ensemble" Projections of Precipitation and Surface Radiation in Support of Agricultural Climate Change Adaptation

    Science.gov (United States)

    Taylor, Patrick C.; Baker, Noel C.

    2015-01-01

    Earth's climate is changing and will continue to change into the foreseeable future. Expected changes in the climatological distribution of precipitation, surface temperature, and surface solar radiation will significantly impact agriculture. Adaptation strategies are, therefore, required to reduce the agricultural impacts of climate change. Climate change projections of precipitation, surface temperature, and surface solar radiation distributions are necessary input for adaption planning studies. These projections are conventionally constructed from an ensemble of climate model simulations (e.g., the Coupled Model Intercomparison Project 5 (CMIP5)) as an equal weighted average, one model one vote. Each climate model, however, represents the array of climate-relevant physical processes with varying degrees of fidelity influencing the projection of individual climate variables differently. Presented here is a new approach, termed the "Intelligent Ensemble, that constructs climate variable projections by weighting each model according to its ability to represent key physical processes, e.g., precipitation probability distribution. This approach provides added value over the equal weighted average method. Physical process metrics applied in the "Intelligent Ensemble" method are created using a combination of NASA and NOAA satellite and surface-based cloud, radiation, temperature, and precipitation data sets. The "Intelligent Ensemble" method is applied to the RCP4.5 and RCP8.5 anthropogenic climate forcing simulations within the CMIP5 archive to develop a set of climate change scenarios for precipitation, temperature, and surface solar radiation in each USDA Farm Resource Region for use in climate change adaptation studies.

  15. p53-dependent adaptive responses in human cells exposed to space radiations.

    Science.gov (United States)

    Takahashi, Akihisa; Su, Xiaoming; Suzuki, Hiromi; Omori, Katsunori; Seki, Masaya; Hashizume, Toko; Shimazu, Toru; Ishioka, Noriaki; Iwasaki, Toshiyasu; Ohnishi, Takeo

    2010-11-15

    It has been reported that priming irradiation or conditioning irradiation with a low dose of X-rays in the range of 0.02-0.1 Gy induces a p53-dependent adaptive response in mammalian cells. The aim of the present study was to clarify the effect of space radiations on the adaptive response. Two human lymphoblastoid cell lines were used; one cell line bears a wild-type p53 (wtp53) gene, and another cell line bears a mutated p53 (mp53) gene. The cells were frozen during transportation on the space shuttle and while in orbit in the International Space Station freezer for 133 days between November 15, 2008 and March 29, 2009. After the frozen samples were returned to Earth, the cells were cultured for 6 h and then exposed to a challenging X-ray-irradiation (2 Gy). Cellular sensitivity, apoptosis, and chromosome aberrations were scored using dye-exclusion assays, Hoechst33342 staining assays, and chromosomal banding techniques, respectively. In cells exposed to space radiations, adaptive responses such as the induction of radioresistance and the depression of radiation-induced apoptosis and chromosome aberrations were observed in wtp53 cells but not in mp53 cells. These results have confirmed the hypothesis that p53-dependent adaptive responses are apparently induced by space radiations within a specific range of low doses. The cells exhibited this effect owing to space radiations exposure, even though the doses in space were very low. Copyright © 2010 Elsevier Inc. All rights reserved.

  16. Evidence for adaptive radiation from a phylogenetic study of plant defenses

    Science.gov (United States)

    Agrawal, Anurag A.; Fishbein, Mark; Halitschke, Rayko; Hastings, Amy P.; Rabosky, Daniel L.; Rasmann, Sergio

    2009-01-01

    One signature of adaptive radiation is a high level of trait change early during the diversification process and a plateau toward the end of the radiation. Although the study of the tempo of evolution has historically been the domain of paleontologists, recently developed phylogenetic tools allow for the rigorous examination of trait evolution in a tremendous diversity of organisms. Enemy-driven adaptive radiation was a key prediction of Ehrlich and Raven's coevolutionary hypothesis [Ehrlich PR, Raven PH (1964) Evolution 18:586–608], yet has remained largely untested. Here we examine patterns of trait evolution in 51 North American milkweed species (Asclepias), using maximum likelihood methods. We study 7 traits of the milkweeds, ranging from seed size and foliar physiological traits to defense traits (cardenolides, latex, and trichomes) previously shown to impact herbivores, including the monarch butterfly. We compare the fit of simple random-walk models of trait evolution to models that incorporate stabilizing selection (Ornstein-Ulenbeck process), as well as time-varying rates of trait evolution. Early bursts of trait evolution were implicated for 2 traits, while stabilizing selection was implicated for several others. We further modeled the relationship between trait change and species diversification while allowing rates of trait evolution to vary during the radiation. Species-rich lineages underwent a proportionately greater decline in latex and cardenolides relative to species-poor lineages, and the rate of trait change was most rapid early in the radiation. An interpretation of this result is that reduced investment in defensive traits accelerated diversification, and disproportionately so, early in the adaptive radiation of milkweeds. PMID:19805160

  17. Convergence across a continent: adaptive diversification in a recent radiation of Australian lizards.

    Science.gov (United States)

    Blom, Mozes P K; Horner, Paul; Moritz, Craig

    2016-06-15

    Recent radiations are important to evolutionary biologists, because they provide an opportunity to study the mechanisms that link micro- and macroevolution. The role of ecological speciation during adaptive radiation has been intensively studied, but radiations can arise from a diversity of evolutionary processes; in particular, on large continental landmasses where allopatric speciation might frequently precede ecological differentiation. It is therefore important to establish a phylogenetic and ecological framework for recent continental-scale radiations that are species-rich and ecologically diverse. Here, we use a genomic (approx. 1 200 loci, exon capture) approach to fit branch lengths on a summary-coalescent species tree and generate a time-calibrated phylogeny for a recent and ecologically diverse radiation of Australian scincid lizards; the genus Cryptoblepharus We then combine the phylogeny with a comprehensive phenotypic dataset for over 800 individuals across the 26 species, and use comparative methods to test whether habitat specialization can explain current patterns of phenotypic variation in ecologically relevant traits. We find significant differences in morphology between species that occur in distinct environments and convergence in ecomorphology with repeated habitat shifts across the continent. These results suggest that isolated analogous habitats have provided parallel ecological opportunity and have repeatedly promoted adaptive diversification. By contrast, speciation processes within the same habitat have resulted in distinct lineages with relatively limited morphological variation. Overall, our study illustrates how alternative diversification processes might have jointly stimulated species proliferation across the continent and generated a remarkably diverse group of Australian lizards. © 2016 The Author(s).

  18. Possible human impacts on adaptive radiation: beak size bimodality in Darwin's finches.

    Science.gov (United States)

    Hendry, Andrew P; Grant, Peter R; Rosemary Grant, B; Ford, Hugh A; Brewer, Mark J; Podos, Jeffrey

    2006-08-07

    Adaptive radiation is facilitated by a rugged adaptive landscape, where fitness peaks correspond to trait values that enhance the use of distinct resources. Different species are thought to occupy the different peaks, with hybrids falling into low-fitness valleys between them. We hypothesize that human activities can smooth adaptive landscapes, increase hybrid fitness and hamper evolutionary diversification. We investigated this possibility by analysing beak size data for 1755 Geospiza fortis measured between 1964 and 2005 on the island of Santa Cruz, Galápagos. Some populations of this species can display a resource-based bimodality in beak size, which mirrors the greater beak size differences among species. We first show that an historically bimodal population at one site, Academy Bay, has lost this property in concert with a marked increase in local human population density. We next show that a nearby site with lower human impacts, El Garrapatero, currently manifests strong bimodality. This comparison suggests that bimodality can persist when human densities are low (Academy Bay in the past, El Garrapatero in the present), but not when they are high (Academy Bay in the present). Human activities may negatively impact diversification in 'young' adaptive radiations, perhaps by altering adaptive landscapes.

  19. A general hybrid radiation transport scheme for star formation simulations on an adaptive grid

    Energy Technology Data Exchange (ETDEWEB)

    Klassen, Mikhail; Pudritz, Ralph E. [Department of Physics and Astronomy, McMaster University 1280 Main Street W, Hamilton, ON L8S 4M1 (Canada); Kuiper, Rolf [Max Planck Institute for Astronomy Königstuhl 17, D-69117 Heidelberg (Germany); Peters, Thomas [Institut für Computergestützte Wissenschaften, Universität Zürich Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Banerjee, Robi; Buntemeyer, Lars, E-mail: klassm@mcmaster.ca [Hamburger Sternwarte, Universität Hamburg Gojenbergsweg 112, D-21029 Hamburg (Germany)

    2014-12-10

    Radiation feedback plays a crucial role in the process of star formation. In order to simulate the thermodynamic evolution of disks, filaments, and the molecular gas surrounding clusters of young stars, we require an efficient and accurate method for solving the radiation transfer problem. We describe the implementation of a hybrid radiation transport scheme in the adaptive grid-based FLASH general magnetohydrodyanmics code. The hybrid scheme splits the radiative transport problem into a raytracing step and a diffusion step. The raytracer captures the first absorption event, as stars irradiate their environments, while the evolution of the diffuse component of the radiation field is handled by a flux-limited diffusion solver. We demonstrate the accuracy of our method through a variety of benchmark tests including the irradiation of a static disk, subcritical and supercritical radiative shocks, and thermal energy equilibration. We also demonstrate the capability of our method for casting shadows and calculating gas and dust temperatures in the presence of multiple stellar sources. Our method enables radiation-hydrodynamic studies of young stellar objects, protostellar disks, and clustered star formation in magnetized, filamentary environments.

  20. Radiation-induced adaptive response in fetal mice: a micro-array study

    International Nuclear Information System (INIS)

    Vares, G.; Bing, Wang; Mitsuru, Nenoi; Tetsuo, Nakajima; Kaoru, Tanaka; Isamu, Hayata

    2006-01-01

    Exposure of sublethal doses of ionizing radiation can induce protective mechanisms against a subsequent higher dose irradiation. This phenomenon called radio-adaptation (or adaptive response - AR), has been described in a wide range of biological models. In a series of studies, we demonstrated the existence of a radiation-induced AR in mice during late organogenesis. For better understanding of molecular mechanisms underlying AR in our model, we performed a global analysis of transcriptome regulations in cells collected from whole mouse fetuses. Using cDNA micro-arrays, we studied gene expression in these cells after in utero priming exposure to irradiation. Several combinations of radiation dose and dose-rate were applied to induce or not an AR in our system. Gene regulation was observed after exposure to priming radiation in each condition. Student's t-test was performed in order to identify genes whose expression modulation was specifically different in AR-inducing an( non-AR-inducing conditions. Genes were ranked according to their ability in discriminating AR-specific modulations. Since AR genes were implicated in variety of functions and cellular processes, we applied a functional classification algorithm, which clustered genes in a limited number of functionally related group: We established that AR genes are significantly enriched for specific keywords. Our results show a significant modulation of genes implicated in signal transduction pathways. No AR-specific alteration of DNA repair could be observed. Nevertheless, it is likely that modulation of DNA repair activity results, at least partly, from post-transcriptional regulation. One major hypothesis is that de-regulations of signal transduction pathways and apoptosis may be responsible for AR phenotype. In previous work, we demonstrated that radiation-induced AR in mice during organogenesis is related to Trp53 gene status and to the occurrence of radiation-induced apoptosis. Other work proposed that p53

  1. DNA excision repair as a component of adaptation to low doses of ionizing radiation Escherichia coli

    International Nuclear Information System (INIS)

    Huang, H.; Claycamp, H.G.

    1993-01-01

    In this study the authors examined whether or not DNA excision repair is a component of adaptation induced by very low-dose ionizing radiation in Escherichia coli, a well-characterized prokaryote, and investigated the relationship between enhanced excision repair and the SOS response. Their data suggest that there seems to be narrow 'windows' of dose-effect for the induction of SOS-independent DNA excision repair. Being similar to mammalian cell studies, the dose range for this effect was about 200-fold less than D 37 for radiation survival. (author)

  2. Evaluation of Online/Offline Image Guidance/Adaptation Approaches for Prostate Cancer Radiation Therapy

    International Nuclear Information System (INIS)

    Qin, An; Sun, Ying; Liang, Jian; Yan, Di

    2015-01-01

    Purpose: To evaluate online/offline image-guided/adaptive treatment techniques for prostate cancer radiation therapy with daily cone-beam CT (CBCT) imaging. Methods and Materials: Three treatment techniques were evaluated retrospectively using daily pre- and posttreatment CBCT images on 22 prostate cancer patients. Prostate, seminal vesicles (SV), rectal wall, and bladder were delineated on all CBCT images. For each patient, a pretreatment intensity modulated radiation therapy plan with clinical target volume (CTV) = prostate + SV and planning target volume (PTV) = CTV + 3 mm was created. The 3 treatment techniques were as follows: (1) Daily Correction: The pretreatment intensity modulated radiation therapy plan was delivered after online CBCT imaging, and position correction; (2) Online Planning: Daily online inverse plans with 3-mm CTV-to-PTV margin were created using online CBCT images, and delivered; and (3) Hybrid Adaption: Daily Correction plus an offline adaptive inverse planning performed after the first week of treatment. The adaptive plan was delivered for all remaining 15 fractions. Treatment dose for each technique was constructed using the daily posttreatment CBCT images via deformable image registration. Evaluation was performed using treatment dose distribution in target and critical organs. Results: Treatment equivalent uniform dose (EUD) for the CTV was within [85.6%, 100.8%] of the pretreatment planned target EUD for Daily Correction; [98.7%, 103.0%] for Online Planning; and [99.2%, 103.4%] for Hybrid Adaptation. Eighteen percent of the 22 patients in Daily Correction had a target dose deficiency >5%. For rectal wall, the mean ± SD of the normalized EUD was 102.6% ± 2.7% for Daily Correction, 99.9% ± 2.5% for Online Planning, and 100.6% ± 2.1% for Hybrid Adaptation. The mean ± SD of the normalized bladder EUD was 108.7% ± 8.2% for Daily Correction, 92.7% ± 8.6% for Online Planning, and 89.4% ± 10.8% for Hybrid

  3. Ecological opportunity and predator-prey interactions: linking eco-evolutionary processes and diversification in adaptive radiations.

    Science.gov (United States)

    Pontarp, Mikael; Petchey, Owen L

    2018-03-14

    Much of life's diversity has arisen through ecological opportunity and adaptive radiations, but the mechanistic underpinning of such diversification is not fully understood. Competition and predation can affect adaptive radiations, but contrasting theoretical and empirical results show that they can both promote and interrupt diversification. A mechanistic understanding of the link between microevolutionary processes and macroevolutionary patterns is thus needed, especially in trophic communities. Here, we use a trait-based eco-evolutionary model to investigate the mechanisms linking competition, predation and adaptive radiations. By combining available micro-evolutionary theory and simulations of adaptive radiations we show that intraspecific competition is crucial for diversification as it induces disruptive selection, in particular in early phases of radiation. The diversification rate is however decreased in later phases owing to interspecific competition as niche availability, and population sizes are decreased. We provide new insight into how predation tends to have a negative effect on prey diversification through decreased population sizes, decreased disruptive selection and through the exclusion of prey from parts of niche space. The seemingly disparate effects of competition and predation on adaptive radiations, listed in the literature, may thus be acting and interacting in the same adaptive radiation at different relative strength as the radiation progresses. © 2018 The Authors.

  4. State of research and perspective on adaptive response to low doses of ionizing radiation in Japan

    International Nuclear Information System (INIS)

    Sadao Hattori

    1997-01-01

    In a review article entitled ''Physical Benefits from Low Levels of Ionizing Radiation,'' published in Health Physics in December of 1982, Professor T.D. Luckey of the University of Missouri, asserted the ''radiation hormesis'' with 200 references. This resulted in the first International Symposium on Radiation Hormesis in Oakland, California (August 1985). CRIEPI consulted many specialists about Luckey's paper and studied many other papers such as Lorenz, 1954; Luckey, 1980, Liu et al., 1985. Radiation hormesis research in Japan has been based on the rationale that if Luckey's claim were to be true, radiation management in Japan has been extremely erroneous. CRIEPI organized a Hormesis Research Steering Committee composed of leading specialists in the field concerned, and began research in cooperation with a number of universities, as well as the National Cancer Research Institute, and the National Institute of Radiological Sciences. After obtaining interesting results in various experiments on the health effects of exposure to low doses of radiation, we have proceeded on an expanded program, which involves fourteen universities and two research institutes throughout Japan. The interesting results we obtained can be categorized in five groups. 1. Enhancement of immune systems such as lymphocytes and suppression of cancer, 2. Radio-adaptive response relating to the activation of DNA repair and adoptosis, 3. Rejuvenation of cells such as increase of SOD and cell membrane permeability, 4. Radiation effect on neuro-transmitting system through increase of key enzymes, 5. Others, including the therapy of adult-disease such as diabetes and hypertension. We are now carrying out experimental activities on the effects of low-dose radiation on mammals. After several years of research activities, we are recognizing Luckey's claim. Some basic surveys including Hiroshima Nagasaki and animal experiments in Japan have brought us valuable informations on the health effects of low

  5. Radiation transport code with adaptive Mesh Refinement: acceleration techniques and applications

    International Nuclear Information System (INIS)

    Velarde, Pedro; Garcia-Fernaandez, Carlos; Portillo, David; Barbas, Alfonso

    2011-01-01

    We present a study of acceleration techniques for solving Sn radiation transport equations with Adaptive Mesh Refinement (AMR). Both DSA and TSA are considered, taking into account the influence of the interaction between different levels of the mesh structure and the order of approximation in angle. A Hybrid method is proposed in order to obtain better convergence rate and lower computer times. Some examples are presented relevant to ICF and X ray secondary sources. (author)

  6. Adaptive Radiation: application in lung cancer; Radioterapia adaptativa: aplicacion en cancer de pulmon

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Mazon, J.; Raba Diez, J. I.; Vazquez Rodriguez, J. a.; Pacheco Baldor, M. T.; Mendiguren Santiago, M. A.; Menendez Garcia, J. C.

    2011-07-01

    The previous updates are a form of adaptive radiation that can be used to account for changes in the size, shape and location of both the tumor and healthy tissue. Are especially useful in the case of lung cancer which typically is associated with significant anatomical changes due to the response to treatment.In the present study, the variation in tumor volume and dosimetric effects from a new CT and replanning during the course of treatment in patients with lung cancer.

  7. Disentangling adaptive evolutionary radiations and the role of diet in promoting diversification on islands

    OpenAIRE

    DeMiguel, Daniel

    2016-01-01

    Although the initial formulation of modern concepts of adaptive radiation arose from consideration of the fossil data, rigorous attempts to identify this phenomenon in the fossil record are largely uncommon. Here I focus on direct evidence of the diet (through tooth-wear patterns) and ecologically-relevant traits of one of the most renowned fossil vertebrates-the Miocene ruminant Hoplitomeryx from the island of Gargano-to deepen our understanding of the most likely causal forces under which a...

  8. Solar Radiation-Associated Adaptive SNP Genetic Differentiation in Wild Emmer Wheat, Triticum dicoccoides.

    Science.gov (United States)

    Ren, Jing; Chen, Liang; Jin, Xiaoli; Zhang, Miaomiao; You, Frank M; Wang, Jirui; Frenkel, Vladimir; Yin, Xuegui; Nevo, Eviatar; Sun, Dongfa; Luo, Ming-Cheng; Peng, Junhua

    2017-01-01

    Whole-genome scans with large number of genetic markers provide the opportunity to investigate local adaptation in natural populations and identify candidate genes under positive selection. In the present study, adaptation genetic differentiation associated with solar radiation was investigated using 695 polymorphic SNP markers in wild emmer wheat originated in a micro-site at Yehudiyya, Israel. The test involved two solar radiation niches: (1) sun, in-between trees; and (2) shade, under tree canopy, separated apart by a distance of 2-4 m. Analysis of molecular variance showed a small (0.53%) but significant portion of overall variation between the sun and shade micro-niches, indicating a non-ignorable genetic differentiation between sun and shade habitats. Fifty SNP markers showed a medium (0.05 ≤ F ST ≤ 0.15) or high genetic differentiation ( F ST > 0.15). A total of 21 outlier loci under positive selection were identified by using four different F ST -outlier testing algorithms. The markers and genome locations under positive selection are consistent with the known patterns of selection. These results suggested that genetic differentiation between sun and shade habitats is substantial, radiation-associated, and therefore ecologically determined. Hence, the results of this study reflected effects of natural selection through solar radiation on EST-related SNP genetic diversity, resulting presumably in different adaptive complexes at a micro-scale divergence. The present work highlights the evolutionary theory and application significance of solar radiation-driven natural selection in wheat improvement.

  9. Phylogenomics Reveals Three Sources of Adaptive Variation during a Rapid Radiation.

    Directory of Open Access Journals (Sweden)

    James B Pease

    2016-02-01

    Full Text Available Speciation events often occur in rapid bursts of diversification, but the ecological and genetic factors that promote these radiations are still much debated. Using whole transcriptomes from all 13 species in the ecologically and reproductively diverse wild tomato clade (Solanum sect. Lycopersicon, we infer the species phylogeny and patterns of genetic diversity in this group. Despite widespread phylogenetic discordance due to the sorting of ancestral variation, we date the origin of this radiation to approximately 2.5 million years ago and find evidence for at least three sources of adaptive genetic variation that fuel diversification. First, we detect introgression both historically between early-branching lineages and recently between individual populations, at specific loci whose functions indicate likely adaptive benefits. Second, we find evidence of lineage-specific de novo evolution for many genes, including loci involved in the production of red fruit color. Finally, using a "PhyloGWAS" approach, we detect environment-specific sorting of ancestral variation among populations that come from different species but share common environmental conditions. Estimated across the whole clade, small but substantial and approximately equal fractions of the euchromatic portion of the genome are inferred to contribute to each of these three sources of adaptive genetic variation. These results indicate that multiple genetic sources can promote rapid diversification and speciation in response to new ecological opportunity, in agreement with our emerging phylogenomic understanding of the complexity of both ancient and recent species radiations.

  10. In vivo study of the adaptive response induced by radiation of different types

    International Nuclear Information System (INIS)

    Klokov, D.Yu.; Zaichkina, S.I.; Rozanova, O.M.; Aptikaeva, G.F.; Akhmadieva, A.Kh.; Smirnova, E.N.; Surkenova, G.N.; Kuzin, A.M.

    2000-01-01

    Low doses of X- and gamma-rays are known to induce the adaptive response (AR), i.e. a reduction in the damage caused by subsequent high doses. Using micronucleus test, we investigated the in vivo induction of AR in mouse bone marrow cells by low doses of radiation of different types. In our experiments we used low-LET gamma-radiation, high-LET secondary radiation from 70 GeV protons and secondary biogenic radiation. The latter is a novel type of radiation discovered only recently. Secondary biogenic radiation is known to be induced in biological objects after exposure to radiation and thought to be responsible for stimulating and protecting effects in cells in response to external irradiation. To expose mice to the secondary biogenic radiation, animals were housed in plastic cages containing gamma-irradiated oat seeds as bedding and food for 2 weeks before challenging with a high dose (1.5 Gy at a dose rate of 1 Gy/min) of 60 Co gamma-radiation. It was found that the yield of cytogenetic damage in mice exposed to both secondary biogenic and gamma-radiation was significantly reduced as compared to that in animals exposed to the challenge dose alone, i.e. the AR was induced. Pretreatment of animals with a low dose of gamma-radiation (0.1 Gy at a dose rate of 0.125 Gy/min) also induced the AR. In contrast, preliminary exposure of mice to a low dose (0.09 Gy at a dose rate of 1 Gy/min) of secondary radiation from 70 GeV protons induced no AR, suggesting that triggering the cascade of events leading to the AR induction depends on the DNA single-strand to double- strand breaks ratio. The precise mechanisms underlying the AR are of great importance since the phenomenon of AR can be used for medical benefits and in assessment of risks for carcinogens. But they have not been elucidated well at present. Taken together, our results suggest the crucial role of particular types of initial DNA lesions and the secondary biogenic radiation induced in cells in response to external

  11. Land radiative management as contributor to regional-scale climate adaptation and mitigation

    Science.gov (United States)

    Seneviratne, Sonia I.; Phipps, Steven J.; Pitman, Andrew J.; Hirsch, Annette L.; Davin, Edouard L.; Donat, Markus G.; Hirschi, Martin; Lenton, Andrew; Wilhelm, Micah; Kravitz, Ben

    2018-02-01

    Greenhouse gas emissions urgently need to be reduced. Even with a step up in mitigation, the goal of limiting global temperature rise to well below 2 °C remains challenging. Consequences of missing these goals are substantial, especially on regional scales. Because progress in the reduction of carbon dioxide emissions has been slow, climate engineering schemes are increasingly being discussed. But global schemes remain controversial and have important shortcomings. A reduction of global mean temperature through global-scale management of solar radiation could lead to strong regional disparities and affect rainfall patterns. On the other hand, active management of land radiative effects on a regional scale represents an alternative option of climate engineering that has been little discussed. Regional land radiative management could help to counteract warming, in particular hot extremes in densely populated and important agricultural regions. Regional land radiative management also raises some ethical issues, and its efficacy would be limited in time and space, depending on crop growing periods and constraints on agricultural management. But through its more regional focus and reliance on tested techniques, regional land radiative management avoids some of the main shortcomings associated with global radiation management. We argue that albedo-related climate benefits of land management should be considered more prominently when assessing regional-scale climate adaptation and mitigation as well as ecosystem services.

  12. Radiation-induced bystander effect and adaptive response in mammalian cells

    Science.gov (United States)

    Zhou, H.; Randers-Pehrson, G.; Waldren, C. A.; Hei, T. K.

    2004-01-01

    Two conflicting phenomena, bystander effect and adaptive response, are important in determining the biological responses at low doses of radiation and have the potential to impact the shape of the dose-response relationship. Using the Columbia University charged-particle microbeam and the highly sensitive AL cell mutagenic assay, we show here that non-irradiated cells acquire mutagenesis through direct contact with cells whose nuclei have been traversed with a single alpha particle each. Pretreatment of cells with a low dose of X-rays four hours before alpha particle irradiation significantly decreased this bystander mutagenic response. Results from the present study address some of the fundamental issues regarding both the actual target and radiation dose effect and can contribute to our current understanding in radiation risk assessment. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

  13. Low-Dose UVA Radiation-Induced Adaptive Response in Cultured Human Dermal Fibroblasts

    Directory of Open Access Journals (Sweden)

    Zhongrong Liu

    2012-01-01

    Full Text Available Objective. To investigate the mechanism of the adaptive response induced by low-dose ultraviolet A (UVA radiation. Methods. Cultured dermal fibroblasts were irradiated by a lethal dose of UVA (86.4 J/cm2 with preirradiation of single or repetitive low dose of UVA (7.2 J/cm2. Alterations of cellular morphology were observed by light microscope and electron microscope. Cell cycle and cellular apoptosis were assayed by flow cytometer. The extent of DNA damage was determined by single-cell gel electrophoresis (SCGE. Results. The cultured dermal fibroblasts, with pretreatment of single or repetitive irradiation of 7.2 J/cm2 UVA relieved toxic reaction of cellular morphology and arrest of cell cycle, decreased apoptosis ratio, reduced DNA chain breakage, and accelerated DNA repair caused by subsequent 86.4 J/cm2 UVA irradiation. Compared with nonpretreatment groups, all those differences were significant (P<0.01 or P<0.05. Conclusions. The adaptation reaction might depend on the accumulated dose of low-dose UVA irradiation. Low-dose UVA radiation might induce adaptive response that may protect cultured dermal fibroblasts from the subsequent challenged dose of UVA damage. The duration and protective capability of the adaptive reaction might be related to the accumulated dose of low-dose UVA Irradiation.

  14. Adaptive planning using megavoltage fan-beam CT for radiation therapy with testicular shielding

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Poonam [Department of Human Oncology, University of Wisconsin, Madison, Madison, WI (United States); Department of Medical Physics, University of Wisconsin, Madison, Madison, WI (United States); School of Advance Sciences, Vellore Institue of Technology University, Vellore, Tamil Nadu (India); Kozak, Kevin [Department of Human Oncology, University of Wisconsin, Madison, Madison, WI (United States); Tolakanahalli, Ranjini [Department of Human Oncology, University of Wisconsin, Madison, Madison, WI (United States); Department of Medical Physics, University of Wisconsin, Madison, Madison, WI (United States); Ramasubramanian, V. [School of Advance Sciences, Vellore Institue of Technology University, Vellore, Tamil Nadu (India); Paliwal, Bhudatt R. [Department of Human Oncology, University of Wisconsin, Madison, Madison, WI (United States); Department of Medical Physics, University of Wisconsin, Madison, Madison, WI (United States); University of Wisconsin, Riverview Cancer Centre, Wisconsin Rapids, WI (United States); Welsh, James S. [Department of Human Oncology, University of Wisconsin, Madison, Madison, WI (United States); Department of Medical Physics, University of Wisconsin, Madison, Madison, WI (United States); Rong, Yi, E-mail: rong@humonc.wisc.edu [Department of Human Oncology, University of Wisconsin, Madison, Madison, WI (United States); University of Wisconsin, Riverview Cancer Centre, Wisconsin Rapids, WI (United States)

    2012-07-01

    This study highlights the use of adaptive planning to accommodate testicular shielding in helical tomotherapy for malignancies of the proximal thigh. Two cases of young men with large soft tissue sarcomas of the proximal thigh are presented. After multidisciplinary evaluation, preoperative radiation therapy was recommended. Both patients were referred for sperm banking and lead shields were used to minimize testicular dose during radiation therapy. To minimize imaging artifacts, kilovoltage CT (kVCT) treatment planning was conducted without shielding. Generous hypothetical contours were generated on each 'planning scan' to estimate the location of the lead shield and generate a directionally blocked helical tomotherapy plan. To ensure the accuracy of each plan, megavoltage fan-beam CT (MVCT) scans were obtained at the first treatment and adaptive planning was performed to account for lead shield placement. Two important regions of interest in these cases were femurs and femoral heads. During adaptive planning for the first patient, it was observed that the virtual lead shield contour on kVCT planning images was significantly larger than the actual lead shield used for treatment. However, for the second patient, it was noted that the size of the virtual lead shield contoured on the kVCT image was significantly smaller than the actual shield size. Thus, new adaptive plans based on MVCT images were generated and used for treatment. The planning target volume was underdosed up to 2% and had higher maximum doses without adaptive planning. In conclusion, the treatment of the upper thigh, particularly in young men, presents several clinical challenges, including preservation of gonadal function. In such circumstances, adaptive planning using MVCT can ensure accurate dose delivery even in the presence of high-density testicular shields.

  15. Adaptive Functioning of Childhood Brain Tumor Survivors following Conformal Radiation Therapy

    Science.gov (United States)

    Ashford, Jason M.; Netson, Kelli L.; Clark, Kellie N.; Merchant, Thomas E.; Santana, Victor M.; Wu, Shengjie; Conklin, Heather M.

    2014-01-01

    Background Adaptive functioning is not often examined in childhood brain tumor (BT) survivors, with the few existing investigations relying on examiner interviews. Parent questionnaires may provide similar information with decreased burden. The purpose of this study was: (1) to examine adaptive behaviors in BT survivors relative to healthy peer and cancer survivor groups, and (2) to explore the validity of a parent questionnaire in relation to an examiner administered interview. Procedure Participants (age 13.11±2.98 years) were BT survivors treated with conformal radiation therapy (n=50), healthy siblings of BT survivors (n=39) and solid tumor (ST) survivors who did not receive CNS-directed therapy (n=40). Parents completed the Adaptive Behavior Assessment System–2nd Edition (ABAS-II). For a subset of the BT cohort (n=32), examiners interviewed the parents using the Vineland Adaptive Behavior Scales (VABS) within 12 months. Results Groups differed significantly on each of the ABAS-II indices and the general adaptive composite, with the BT group scoring lower than the sibling and ST groups across indices. Executive functioning, but not IQ, was associated with adaptive skills; no clear pattern of clinical and demographic predictors was established. VABS scores were correlated with ABAS-II scores on nearly all indices. Conclusions BT survivors showed significantly lower adaptive functioning when compared to healthy and cancer controls. The ABAS-II proved sensitive to these behavioral limitations and was consistent with scores on the VABS. The use of a parent questionnaire to assess adaptive functioning enhances survivorship investigations by increasing flexibility of assessment and decreasing examiner burden. PMID:24658934

  16. Optical solar energy adaptations and radiative temperature control of green leaves and tree barks

    Energy Technology Data Exchange (ETDEWEB)

    Henrion, Wolfgang; Tributsch, Helmut [Department of Si-Photovoltaik and Solare Energetik, Hahn-Meitner-Institut Berlin, 14109 Berlin (Germany)

    2009-01-15

    Trees have adapted to keep leaves and barks cool in sunshine and can serve as interesting bionic model systems for radiative cooling. Silicon solar cells, on the other hand, loose up to one third of their energy efficiency due to heating in intensive sunshine. It is shown that green leaves minimize absorption of useful radiation and allow efficient infrared thermal emission. Since elevated temperatures are detrimental for tensile water flow in the Xylem tissue below barks, the optical properties of barks should also have evolved so as to avoid excessive heating. This was tested by performing optical studies with tree bark samples from representative trees. It was found that tree barks have optimized their reflection of incoming sunlight between 0.7 and 2 {mu}m. This is approximately the optical window in which solar light is transmitted and reflected by green vegetation. Simultaneously, the tree bark is highly absorbing and thus radiation emitting between 6 and 10 {mu}m. These two properties, mainly provided by tannins, create optimal conditions for radiative temperature control. In addition, tannins seem to have adopted a function as mediators for excitation energy towards photo-antioxidative activity for control of radiation damage. The results obtained are used to discuss challenges for future solar cell optimization. (author)

  17. Androgen Induces Adaptation to Oxidative Stress in Prostate Cancer: Implications for Treatment with Radiation Therapy

    Directory of Open Access Journals (Sweden)

    Jehonathan H. Pinthus

    2007-01-01

    Full Text Available Radiation therapy is a standard treatment for prostate cancer (PC. The postulated mechanism of action for radiation therapy is the generation of reactive oxygen species (ROS. Adjuvant androgen deprivation (AD therapy has been shown to confer a survival advantage over radiation alone in high-risk localized PC. However, the mechanism of this interaction is unclear. We hypothesize that androgens modify the radioresponsiveness of PC through the regulation of cellular oxidative homeostasis. Using androgen receptor (AR+ 22rv1 and AR− PC3 human PC cell lines, we demonstrated that testosterone increased basal reactive oxygen species (bROS levels, resulting in dose-dependent activation of phospho-p38 and pAKT, increased expression of clusterin, catalase, manganese superoxide dismutase. Similar data were obtained in three human PC xenografts; WISH-PC14, WISH-PC23, CWR22, growing in testosterone-supplemented or castrated SCID mice. These effects were reversible through AD or through incubation with a reducing agent. Moreover, testosterone increased the activity of catalase, superoxide dismutases, glutathione reductase. Consequently, AD significantly facilitated the response of AR+ cells to oxidative stress challenge. Thus, testosterone induces a preset cellular adaptation to radiation through the generation of elevated bROS, which is modified by AD. These findings provide a rational for combined hormonal and radiation therapy for localized PC.

  18. Linearized Flux Evolution (LiFE): A technique for rapidly adapting fluxes from full-physics radiative transfer models

    Science.gov (United States)

    Robinson, Tyler D.; Crisp, David

    2018-05-01

    Solar and thermal radiation are critical aspects of planetary climate, with gradients in radiative energy fluxes driving heating and cooling. Climate models require that radiative transfer tools be versatile, computationally efficient, and accurate. Here, we describe a technique that uses an accurate full-physics radiative transfer model to generate a set of atmospheric radiative quantities which can be used to linearly adapt radiative flux profiles to changes in the atmospheric and surface state-the Linearized Flux Evolution (LiFE) approach. These radiative quantities describe how each model layer in a plane-parallel atmosphere reflects and transmits light, as well as how the layer generates diffuse radiation by thermal emission and by scattering light from the direct solar beam. By computing derivatives of these layer radiative properties with respect to dynamic elements of the atmospheric state, we can then efficiently adapt the flux profiles computed by the full-physics model to new atmospheric states. We validate the LiFE approach, and then apply this approach to Mars, Earth, and Venus, demonstrating the information contained in the layer radiative properties and their derivatives, as well as how the LiFE approach can be used to determine the thermal structure of radiative and radiative-convective equilibrium states in one-dimensional atmospheric models.

  19. A 5-Year Investigation of Children's Adaptive Functioning Following Conformal Radiation Therapy for Localized Ependymoma

    International Nuclear Information System (INIS)

    Netson, Kelli L.; Conklin, Heather M.; Wu Shengjie; Xiong Xiaoping; Merchant, Thomas E.

    2012-01-01

    Purpose: Conformal and intensity modulated radiation therapies have the potential to preserve cognitive outcomes in children with ependymoma; however, functional behavior remains uninvestigated. This longitudinal investigation prospectively examined intelligence quotient (IQ) and adaptive functioning during the first 5 years after irradiation in children diagnosed with ependymoma. Methods and Materials: The study cohort consisted of 123 children with intracranial ependymoma. Mean age at irradiation was 4.60 years (95% confidence interval [CI], 3.85-5.35). Serial neurocognitive evaluations, including an age-appropriate IQ measure and the Vineland Adaptive Behavior Scales (VABS), were completed before irradiation, 6 months after treatment, and annually for 5 years. A total of 579 neurocognitive evaluations were included in these analyses. Results: Baseline IQ and VABS were below normative means (P<.05), although within the average range. Linear mixed models revealed stable IQ and VABS across the follow-up period, except for the VABS Communication Index, which declined significantly (P=.015). Annual change in IQ (−.04 points) did not correlate with annual change in VABS (−.90 to +.44 points). Clinical factors associated with poorer baseline performance (P<.05) included preirradiation chemotherapy, cerebrospinal fluid shunt placement, number and extent of surgical resections, and younger age at treatment. No clinical factors significantly affected the rate of change in scores. Conclusions: Conformal and intensity modulated radiation therapies provided relative sparing of functional outcomes including IQ and adaptive behaviors, even in very young children. Communication skills remained vulnerable and should be the target of preventive and rehabilitative interventions.

  20. Radiation-induced apoptosis in human tumor cell lines: adaptive response and split-dose effect.

    Science.gov (United States)

    Filippovich, I V; Sorokina, N I; Robillard, N; Lisbona, A; Chatal, J F

    1998-07-03

    Irradiation of human ovarian carcinoma cells (OVCAR 3) and myeloma cells (RPMI 8226) with graded doses of 137Cs-gamma-rays led to a 35-40% increase in time-dependent apoptosis 72 hr after 6-8 Gy irradiation. Large individual variations in sensitivity to radiation-induced apoptosis were noted in human lymphocytes obtained from 5 donors. Pretreatment of OVCAR 3 and RPMI 8226 cells with 0.01 Gy increased their resistance to apoptosis after subsequent 6 Gy irradiation several hours or 48 and 72 hr later. A dose of 4 or 8 Gy given in 2 equal fractions at an interval of a few hours produced a low level of apoptosis compared to that resulting from a single administration of the same total dose. Adaptive response was demonstrated in 2 out of 3 samples of human lymphocytes isolated from different donors, and no split-dose effect for apoptosis was noted in 2 other donors. In split-dose experiments, there was no correlation between the sensitivity of cells to apoptosis and their position in the cell cycle, after the first half-dose. No G1 block was observed in irradiated cell lines. Adaptive response and split-dose effect were prevented by 3-aminobenzamide and okadaic acid which inhibit poly(ADP-ribose)polymerase and protein phosphatase, respectively. These results imply a common mechanism for acquired resistance to radiation-induced apoptosis in adaptive response and the split-dose effect.

  1. Adaptive radiation therapy for postprostatectomy patients using real-time electromagnetic target motion tracking during external beam radiation therapy.

    Science.gov (United States)

    Zhu, Mingyao; Bharat, Shyam; Michalski, Jeff M; Gay, Hiram A; Hou, Wei-Hsien; Parikh, Parag J

    2013-03-15

    Using real-time electromagnetic (EM) transponder tracking data recorded by the Calypso 4D Localization System, we report inter- and intrafractional target motion of the prostate bed, describe a strategy to evaluate treatment adequacy in postprostatectomy patients receiving intensity modulated radiation therapy (IMRT), and propose an adaptive workflow. Tracking data recorded by Calypso EM transponders was analyzed for postprostatectomy patients that underwent step-and-shoot IMRT. Rigid target motion parameters during beam delivery were calculated from recorded transponder positions in 16 patients with rigid transponder geometry. The delivered doses to the clinical target volume (CTV) were estimated from the planned dose matrix and the target motion for the first 3, 5, 10, and all fractions. Treatment adequacy was determined by comparing the delivered minimum dose (Dmin) with the planned Dmin to the CTV. Treatments were considered adequate if the delivered CTV Dmin is at least 95% of the planned CTV Dmin. Translational target motion was minimal for all 16 patients (mean: 0.02 cm; range: -0.12 cm to 0.07 cm). Rotational motion was patient-specific, and maximum pitch, yaw, and roll were 12.2, 4.1, and 10.5°, respectively. We observed inadequate treatments in 5 patients. In these treatments, we observed greater target rotations along with large distances between the CTV centroid and transponder centroid. The treatment adequacy from the initial 10 fractions successfully predicted the overall adequacy in 4 of 5 inadequate treatments and 10 of 11 adequate treatments. Target rotational motion could cause underdosage to partial volume of the postprostatectomy targets. Our adaptive treatment strategy is applicable to post-prostatectomy patients receiving IMRT to evaluate and improve radiation therapy delivery. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Factors driving adaptive radiation in plants of oceanic islands: a case study from the Juan Fernández Archipelago.

    Science.gov (United States)

    Takayama, Koji; Crawford, Daniel J; López-Sepúlveda, Patricio; Greimler, Josef; Stuessy, Tod F

    2018-03-13

    Adaptive radiation is a common evolutionary phenomenon in oceanic islands. From one successful immigrant population, dispersal into different island environments and directional selection can rapidly yield a series of morphologically distinct species, each adapted to its own particular environment. Not all island immigrants, however, follow this evolutionary pathway. Others successfully arrive and establish viable populations, but they remain in the same ecological zone and only slowly diverge over millions of years. This transformational speciation, or anagenesis, is also common in oceanic archipelagos. The critical question is why do some groups radiate adaptively and others not? The Juan Fernández Islands contain 105 endemic taxa of angiosperms, 49% of which have originated by adaptive radiation (cladogenesis) and 51% by anagenesis, hence providing an opportunity to examine characteristics of taxa that have undergone both types of speciation in the same general island environment. Life form, dispersal mode, and total number of species in progenitors (genera) of endemic angiosperms in the archipelago were investigated from literature sources and compared with modes of speciation (cladogenesis vs. anagenesis). It is suggested that immigrants tending to undergo adaptive radiation are herbaceous perennial herbs, with leaky self-incompatible breeding systems, good intra-island dispersal capabilities, and flexible structural and physiological systems. Perhaps more importantly, the progenitors of adaptively radiated groups in islands are those that have already been successful in adaptations to different environments in source areas, and which have also undergone eco-geographic speciation. Evolutionary success via adaptive radiation in oceanic islands, therefore, is less a novel feature of island lineages but rather a continuation of tendency for successful adaptive speciation in lineages of continental source regions.

  3. A Clinical Concept for Interfractional Adaptive Radiation Therapy in the Treatment of Head and Neck Cancer

    International Nuclear Information System (INIS)

    Jensen, Alexandra D.; Nill, Simeon; Huber, Peter E.; Bendl, Rolf; Debus, Jürgen; Münter, Marc W.

    2012-01-01

    Purpose: To present an approach to fast, interfractional adaptive RT in intensity-modulated radiation therapy (IMRT) of head and neck tumors in clinical routine. Ensuring adequate patient position throughout treatment proves challenging in high-precision RT despite elaborate immobilization. Because of weight loss, treatment plans must be adapted to account for requiring supportive therapy incl. feeding tube or parenteral nutrition without treatment breaks. Methods and Materials: In-room CT position checks are used to create adapted IMRT treatment plans by stereotactic correlation to the initial setup, and volumes are adapted to the new geometry. New IMRT treatment plans are prospectively created on the basis of position control scans using the initial optimization parameters in KonRad without requiring complete reoptimization and thus facilitating quick replanning in daily routine. Patients treated for squamous cell head and neck cancer (SCCHN) in 2006–2007 were evaluated as to necessity/number of replannings, weight loss, dose, and plan parameters. Results: Seventy-two patients with SCCHN received IMRT to the primary site and lymph nodes (median dose 70.4 Gy). All patients received concomitant chemotherapy requiring supportive therapy by feeding tube or parenteral nutrition. Median weight loss was 7.8 kg, median volume loss was approximately 7%. Fifteen of 72 patients required adaptation of their treatment plans at least once. Target coverage was improved by up to 10.7% (median dose). The increase of dose to spared parotid without replanning was 11.7%. Replanning including outlining and optimization was feasible within 2 hours for each patient, and treatment could be continued without any interruptions. Conclusion: To preserve high-quality dose application, treatment plans must be adapted to anatomical changes. Replanning based on position control scans therefore presents a practical approach in clinical routine. In the absence of clinically usable online

  4. Psychophysiological adaptation of the patient with the remote effect of the III degree acute radiation syndrome

    Directory of Open Access Journals (Sweden)

    Metlyaeva N.A.

    2013-12-01

    putation of both shins at level in top / 3, late beam buttock, right hip ulcers, a beam cataract of the III degree of both eyes, stabilized. The assessment of the efficiency of psychophysiological adaptation in dynamics with 2009 indicates emergence of prevalence of hypochondriac tendencies over a demonstration with accession of high uneasiness and autistic lines at preservation of the leading role of an hypochondriac somatization of alarm with considerable decrease in an emotionality, an integration, a freedom of behavior. The changes revealed in dynamics correspond to the specific increase weight of violations of mental adaptation, characteristic for the period of adaptation exhaustion. The high intelligence, good figurative and logical thinking, well-mannered forms of behavior, high control over the emotional sphere, restraint of emotions, independence, self-sufficiency, organization, behavior taking into account environment requirements provided the patient M. firmness before a heavy illness, promoted good adaptation to an environment with confidence in myself, high social adaptability, opportunity successfully to carry out duties, hold the work account (worked 39 years after accident. Comparative assessment of operator ability of the patient M. showed good average time of common and difficult sensorimotor reactions with 2 mistakes, high time of reaction for moving object, however decrease in accuracy of reaction from 10-13% to 2% testifies to manifestation in dynamics of insufficiency of real functional reserves of nervous system. Conclusions. Efficiency of psychophysiological adaptation depends not only on a dose of radiation and weight of the transferred disease, but, mostly, on premorbid properties of the identity of the victim and his social and labor installation.

  5. Glutathione (GSH Production as Protective Adaptation Against Light Regime Radiation of Symbiodinium Natural Population

    Directory of Open Access Journals (Sweden)

    Moh Muhaemin

    2017-08-01

    Full Text Available Glutathione (GSH, as a wide range of low molecular weight, which found in marine microalgae and event bacteria, are essential to prevent photooxidation and productivity loss from these Radical Oxigen Species (ROS. Symbiodinium, endo-symbiont of corals, were exposed with different UV radiation combined with irradiance treatments to explore biomass specific initial response. Intracellular glutahione was observed as potential adaptive response of Symbiodinium population under environmental specific stress. The result showed that GSH production increased significantly with increasing irradiance and/or UV levels. GSH concentration was fluctuated among populations exposed by different irradiance treatments, but not effected by UV and irradiance exposure. GSH production as a response of UV exposure was higher than irradiance treatments. Both these high correlative fluctuation of intracellular GSH production and the presence of both treatments indicated protective specific adaptation of Symbiodinium under specific environmental stress, respectively.   Keywords: zooxanthellae, irradiance, glutathione (GSH, corals, Fungia

  6. Adaptive radiation with regard to nutrient sequestration strategies in the carnivorous plants of the genus Nepenthes.

    Science.gov (United States)

    Pavlovič, Andrej

    2012-02-01

    Carnivorous pitcher plants of the genus Nepenthes have evolved a great diversity of pitcher morphologies. Selective pressures for maximizing nutrient uptake have driven speciation and diversification of the genus in a process known as adaptive radiation. This leads to the evolution of pitchers adapted to specific and often bizarre source of nutrients, which are not strictly animal-derived. One example is Nepenthes ampullaria with unusual growth pattern and pitcher morphology what enables the plant to capture a leaf litter from the canopy above. We showed that the plant benefits from nitrogen uptake by increased rate of photosynthesis and growth what may provide competitive advantage over others co-habiting plants. A possible impact of such specialization toward hybridization, an important mechanism in speciation, is discussed.

  7. Cytogenetic monitoring, radiosensitivity study and adaptive response of workers exposed to low level ionizing radiation

    International Nuclear Information System (INIS)

    Peitl Junior, Paulo

    1996-01-01

    The objectives of the present study were: To determine the frequencies of chromosome aberrations in lymphocytes from individuals belonging to professionally exposed groups, under normal conditions; to determine the possible differences in radiosensitivity between the lymphocytes of technicians and controls after in vitro irradiation with gamma rays during the G 1 phase of the cell cycle (radiosensitivity study), and to examine the influence of in vivo and in vitro pre-exposure to low doses of radiation on the frequency of chromosome aberrations induced in vitro by high doses (study of the adaptive response) in a group of technicians (T) compared to controls (C). (author)

  8. Conservatism and adaptability during squirrel radiation: what is mandible shape telling us?

    Directory of Open Access Journals (Sweden)

    Isaac Casanovas-Vilar

    Full Text Available Both functional adaptation and phylogeny shape the morphology of taxa within clades. Herein we explore these two factors in an integrated way by analyzing shape and size variation in the mandible of extant squirrels using landmark-based geometric morphometrics in combination with a comparative phylogenetic analysis. Dietary specialization and locomotion were found to be reliable predictors of mandible shape, with the prediction by locomotion probably reflecting the underlying diet. In addition a weak but significant allometric effect could be demonstrated. Our results found a strong phylogenetic signal in the family as a whole as well as in the main clades, which is in agreement with the general notion of squirrels being a conservative group. This fact does not preclude functional explanations for mandible shape, but rather indicates that ancient adaptations kept a prominent role, with most genera having diverged little from their ancestral clade morphologies. Nevertheless, certain groups have evolved conspicuous adaptations that allow them to specialize on unique dietary resources. Such adaptations mostly occurred in the Callosciurinae and probably reflect their radiation into the numerous ecological niches of the tropical and subtropical forests of Southeastern Asia. Our dietary reconstruction for the oldest known fossil squirrels (Eocene, 36 million years ago show a specialization on nuts and seeds, implying that the development from protrogomorphous to sciuromorphous skulls was not necessarily related to a change in diet.

  9. Online Magnetic Resonance Image Guided Adaptive Radiation Therapy: First Clinical Applications

    International Nuclear Information System (INIS)

    Acharya, Sahaja; Fischer-Valuck, Benjamin W.; Kashani, Rojano; Parikh, Parag; Yang, Deshan; Zhao, Tianyu; Green, Olga; Wooten, Omar; Li, H. Harold; Hu, Yanle; Rodriguez, Vivian; Olsen, Lindsey; Robinson, Clifford; Michalski, Jeff; Mutic, Sasa; Olsen, Jeffrey

    2016-01-01

    Purpose: To demonstrate the feasibility of online adaptive magnetic resonance (MR) image guided radiation therapy (MR-IGRT) through reporting of our initial clinical experience and workflow considerations. Methods and Materials: The first clinically deployed online adaptive MR-IGRT system consisted of a split 0.35T MR scanner straddling a ring gantry with 3 multileaf collimator-equipped 60 Co heads. The unit is supported by a Monte Carlo–based treatment planning system that allows real-time adaptive planning with the patient on the table. All patients undergo computed tomography and MR imaging (MRI) simulation for initial treatment planning. A volumetric MRI scan is acquired for each patient at the daily treatment setup. Deformable registration is performed using the planning computed tomography data set, which allows for the transfer of the initial contours and the electron density map to the daily MRI scan. The deformed electron density map is then used to recalculate the original plan on the daily MRI scan for physician evaluation. Recontouring and plan reoptimization are performed when required, and patient-specific quality assurance (QA) is performed using an independent in-house software system. Results: The first online adaptive MR-IGRT treatments consisted of 5 patients with abdominopelvic malignancies. The clinical setting included neoadjuvant colorectal (n=3), unresectable gastric (n=1), and unresectable pheochromocytoma (n=1). Recontouring and reoptimization were deemed necessary for 3 of 5 patients, and the initial plan was deemed sufficient for 2 of the 5 patients. The reasons for plan adaptation included tumor progression or regression and a change in small bowel anatomy. In a subsequently expanded cohort of 170 fractions (20 patients), 52 fractions (30.6%) were reoptimized online, and 92 fractions (54.1%) were treated with an online-adapted or previously adapted plan. The median time for recontouring, reoptimization, and QA was 26

  10. Benefits of adaptive radiation therapy in lung cancer as a function of replanning frequency

    International Nuclear Information System (INIS)

    Dial, Christian; Weiss, Elisabeth; Hugo, Geoffrey D.; Siebers, Jeffrey V.

    2016-01-01

    Purpose: To quantify the potential benefit associated with daily replanning in lung cancer in terms of normal tissue dose sparing and to characterize the tradeoff between adaptive benefit and replanning frequency. Methods: A set of synthetic images and contours, derived from weekly active breathing control images of 12 patients who underwent radiation therapy treatment for nonsmall cell lung cancer, is generated for each fraction of treatment using principal component analysis in a way that preserves temporal anatomical trends (e.g., tumor regression). Daily synthetic images and contours are used to simulate four different treatment scenarios: (1) a “no-adapt” scenario that simulates delivery of an initial plan throughout treatment, (2) a “midadapt” scenario that implements a single replan for fraction 18, (3) a “weekly adapt” scenario that simulates weekly adaptations, and (4) a “full-adapt” scenario that simulates daily replanning. An initial intensity modulated radiation therapy plan is created for each patient and replanning is carried out in an automated fashion by reoptimizing beam apertures and weights. Dose is calculated on each image and accumulated to the first in the series using deformable mappings utilized in synthetic image creation for comparison between simulated treatments. Results: Target coverage was maintained and cord tolerance was not exceeded for any of the adaptive simulations. Average reductions in mean lung dose (MLD) and volume of lung receiving 20 Gy or more (V20 lung ) were 65 ± 49 cGy (p = 0.000 01) and 1.1% ± 1.2% (p = 0.0006), respectively, for all patients. The largest reduction in MLD for a single patient was 162 cGy, which allowed an isotoxic escalation of the target dose of 1668 cGy. Average reductions in cord max dose, mean esophageal dose (MED), dose received by 66% of the heart (D66 heart ), and dose received by 33% of the heart (D33 heart ), were 158 ± 280, 117 ± 121, 37 ± 77, and 99 ± 120 c

  11. Adaptive response of yeast cultures (Saccharomyces Cerevisiae) exposed to low dose of gamma radiation

    International Nuclear Information System (INIS)

    Kulcsar, Agnes; Savu, D.; Petcu, I.; Gherasim, Raluca

    2003-01-01

    The present study was planned as follows: (i) setting up of standard experimental conditions for investigation of radio-induced adaptive response in lower Eucaryotes; (ii) developing of procedures for synchronizing Saccharomyces cerevisiae X 310 D cell cultures and cell cycle stages monitoring; (iii) investigation of gamma (Co-60) and UV irradiation effects on the viability of synchronized and non-synchronized cell cultures of Saccharomyces cerevisiae; the effects were correlated with the cell density and cell cycle stage; (iv) study of the adaptive response induced by irradiation and setting up of the experimental conditions for which this response is optimized. The irradiations were performed by using a Co-60 with doses of 10 2 - 10 4 Gy and dose rates ranging from 2.2 x 10 2 Gy/h to 8.7 x 10 3 Gy/h. The study of radioinduced adaptive response was performed by applying a pre-irradiation treatment of 100-500 Gy, followed by challenge doses of 2-4 kGy delivered at different time intervals, ranging from 1 h to 4 h. The survival rate of synchronized and non-synchronized cultures as a function of exposure dose shows an exponential decay shape. No difference in viability of the cells occurred between synchronized and non-synchronized cultures. The pre-irradiation of cells with 100 and 200 Gy were most efficient to induce an adaptive response for the yeast cells. In this stage of work we proved the occurrence of the adaptive response in the case of synchronized yeast cultures exposed to gamma radiation. The results will be used in the future to investigate the dependence of this response on the cell cycle and the possibility to induce such a response by a low level electromagnetic field. (authors)

  12. GPU-based ultra-fast direct aperture optimization for online adaptive radiation therapy

    Science.gov (United States)

    Men, Chunhua; Jia, Xun; Jiang, Steve B.

    2010-08-01

    Online adaptive radiation therapy (ART) has great promise to significantly reduce normal tissue toxicity and/or improve tumor control through real-time treatment adaptations based on the current patient anatomy. However, the major technical obstacle for clinical realization of online ART, namely the inability to achieve real-time efficiency in treatment re-planning, has yet to be solved. To overcome this challenge, this paper presents our work on the implementation of an intensity-modulated radiation therapy (IMRT) direct aperture optimization (DAO) algorithm on the graphics processing unit (GPU) based on our previous work on the CPU. We formulate the DAO problem as a large-scale convex programming problem, and use an exact method called the column generation approach to deal with its extremely large dimensionality on the GPU. Five 9-field prostate and five 5-field head-and-neck IMRT clinical cases with 5 × 5 mm2 beamlet size and 2.5 × 2.5 × 2.5 mm3 voxel size were tested to evaluate our algorithm on the GPU. It takes only 0.7-3.8 s for our implementation to generate high-quality treatment plans on an NVIDIA Tesla C1060 GPU card. Our work has therefore solved a major problem in developing ultra-fast (re-)planning technologies for online ART.

  13. Distinct evolutionary patterns of brain and body size during adaptive radiation.

    Science.gov (United States)

    Gonzalez-Voyer, Alejandro; Winberg, Svante; Kolm, Niclas

    2009-09-01

    Morphological traits are often genetically and/or phenotypically correlated with each other and such covariation can have an important influence on the evolution of individual traits. The strong positive relationship between brain size and body size in vertebrates has attracted a lot of interest, and much debate has surrounded the study of the factors responsible for the allometric relationship between these two traits. Here, we use comparative analyses of the Tanganyikan cichlid adaptive radiation to investigate the patterns of evolution for brain size and body size separately. We found that body size exhibited recent bursts of rapid evolution, a pattern that is consistent with divergence linked to ecological specialization. Brain weight on the other hand, showed no bursts of divergence but rather evolved in a gradual manner. Our results thus show that even highly genetically correlated traits can present markedly different patterns of evolution, hence interpreting patterns of evolution of traits from correlations in extant taxa can be misleading. Furthermore, our results suggest, contrary to expectations from theory, that brain size does not play a key role during adaptive radiation.

  14. Applications of deformable image registration: Automatic segmentation and adaptive radiation therapy

    Science.gov (United States)

    Morcos, Marc

    The contents of this thesis are best divided into two components: (i) evaluation of atlas-based segmentation and deformable contour propagation and (ii) adaptive radiation therapy using deformable electron density mapping. The first component of this thesis involves the evaluation of two commercial deformable registration systems with respect to automatic segmentation techniques. Overall, the techniques revealed that manual modifications would be required if the structures were to be used for treatment planning. The automatic segmentation methods utilized by both commercial products serve as an excellent starting point for contouring process and also reduce inter- and intra-physician variability when contouring. In the second component, we developed a framework for dose accumulation adaptive radiation therapy. By registering the planning computed tomography (CT) images to the weekly cone-beam computed tomography (CBCT) images, we were able to produce modified CBCT images which possessed CT Hounsfield units; this was achieved by using deformable image registration. Dose distributions were recalculated onto the modified CBCT images and then compared to the planned dose distributions. Results indicated that deformable electron density mapping is a feasible technique to allow dose distributions to be recalculated on pre-treatment CBCT scans.

  15. Niche evolution and adaptive radiation: Testing the order of trait divergence

    Science.gov (United States)

    Ackerly, D.D.; Schwilk, D.W.; Webb, C.O.

    2006-01-01

    In the course of an adaptive radiation, the evolution of niche parameters is of particular interest for understanding modes of speciation and the consequences for coexistence of related species within communities. We pose a general question: In the course of an evolutionary radiation, do traits related to within-community niche differences (?? niche) evolve before or after differentiation of macrohabitat affinity or climatic tolerances (?? niche)? Here we introduce a new test to address this question, based on a modification of the method of independent contrasts. The divergence order test (DOT) is based on the average age of the nodes on a tree, weighted by the absolute magnitude of the contrast at each node for a particular trait. The comparison of these weighted averages reveals whether large divergences for one trait have occurred earlier or later in the course of diversification, relative to a second trait; significance is determined by bootstrapping from maximum-likelihood ancestral state reconstructions. The method is applied to the evolution of Ceanothus, a woody plant group in California, in which co-occurring species exhibit significant differences in a key leaf trait (specific leaf area) associated with contrasting physiological and life history strategies. Co-occurring species differ more for this trait than expected under a null model of community assembly. This ?? niche difference evolved early in the divergence of two major subclades within Ceanothus, whereas climatic distributions (?? niche traits) diversified later within each of the subclades. However, rapid evolution of climate parameters makes inferences of early divergence events highly uncertain, and differentiation of the ?? niche might have taken place throughout the evolution of the group, without leaving a clear phylogenetic signal. Similar patterns observed in several plant and animal groups suggest that early divergence of ?? niche traits might be a common feature of niche evolution in

  16. Evolutionary Influences of Plastic Behavioral Responses Upon Environmental Challenges in an Adaptive Radiation.

    Science.gov (United States)

    Foster, Susan A; Wund, Matthew A; Baker, John A

    2015-09-01

    At the end of the 19th century, the suggestion was made by several scientists, including J. M. Baldwin, that behavioral responses to environmental change could both rescue populations from extinction (Baldwin Effect) and influence the course of subsequent evolution. Here we provide the historical and theoretical background for this argument and offer evidence of the importance of these ideas for understanding how animals (and other organisms that exhibit behavior) will respond to the rapid environmental changes caused by human activity. We offer examples from long-term research on the evolution of behavioral and other phenotypes in the adaptive radiation of the threespine stickleback fish (Gasterosteus aculeatus), a radiation in which it is possible to infer ancestral patterns of behavioral plasticity relative to the post-glacial freshwater radiation in northwestern North America, and to use patterns of parallelism and contemporary evolution to understand adaptive causes of responses to environmental modification. Our work offers insights into the complexity of cognitive responses to environmental change, and into the importance of examining multiple aspects of the phenotype simultaneously, if we are to understand how behavioral shifts contribute to the persistence of populations and to subsequent evolution. We conclude by discussing the origins of apparent novelties induced by environmental shifts, and the importance of accounting for geographic variation within species if we are to accurately anticipate the effects of anthropogenic environmental modification on the persistence and evolution of animals. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

  17. Mutagenic adaptive response to high-LET radiation in human lymphoblastoid cells exposed to X-rays.

    Science.gov (United States)

    Varès, Guillaume; Wang, Bing; Tanaka, Kaoru; Kakimoto, Ayana; Eguchi-Kasai, Kyomi; Nenoi, Mitsuru

    2011-01-10

    The ability of cells to adapt low-dose or low-dose rate radiation is well known. High-LET radiation has unique characteristics, and the data concerning low doses effects and high-LET radiation remain fragmented. In this study, we assessed in vitro the ability of low doses of X-rays to induce an adaptive response (AR) to a subsequent challenging dose of heavy-ion radiation. Lymphoblastoid cells (TK6, AHH-1, NH32) were exposed to priming 0.02-0.1Gy X-rays, followed 6h later by challenging 1Gy heavy-ion radiation (carbon-ion: 20 and 40keV/μm, neon-ion: 150keV/μm). Pre-exposure of p53-competent cells resulted in decreased mutation frequencies at hypoxanthine-guanine phosphoribosyl transferase locus and different H2AX phosphorylation kinetics, as compared to cells exposed to challenging radiation alone. This phenomenon did not seem to be linked with cell cycle effects or radiation-induced apoptosis. Taken together, our results suggested the existence of an AR to mutagenic effects of heavy-ion radiation in lymphoblastoid cells and the involvement of double-strand break repair mechanisms. Copyright © 2010 Elsevier B.V. All rights reserved.

  18. Parasites contribute to ecologically dependent postmating isolation in the adaptive radiation of three-spined stickleback.

    Science.gov (United States)

    El Nagar, Aliya; MacColl, Andrew D C

    2016-08-17

    Spatial variation in parasitic infections is common, and has the potential to drive population divergence and the reproductive isolation of hosts. However, despite support from theory and model laboratory systems, little strong evidence has been forthcoming from the wild. Here, we show that parasites are likely to cause reproductive isolation in the adaptive radiation of three-spined stickleback. Adjacent wild populations on the Scottish island of North Uist differ greatly and consistently in the occurrence of different parasites that have substantial effects on fitness. Laboratory-reared fish are more resistant to experimental infection by parasite species from their own population. Furthermore, hybrid backcrosses between the host populations are more resistant to parasites from the parental population to which they are more closely related. These patterns provide strong evidence that parasites can cause ecological speciation, by contributing to selection against migrants and ecologically dependent postmating isolation. © 2016 The Author(s).

  19. Studies of adaptive response and mutation induction in MCF-10A cells following exposure to chronic or acute ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Manesh, Sara Shakeri; Sangsuwan, Traimate; Wojcik, Andrzej; Haghdoost, Siamak, E-mail: Siamak.haghdoost@su.se

    2015-10-15

    Highlights: • 50 mGy at 1.4 mGy/h induces adaptive response in MCF-10A at mutation level. • Low dose rate γ-radiation does not induce adaptive response at survival level. • Overall, a dose rate effect is absent at the level of mutation in MCF-10A cells. - Abstract: A phenomenon in which exposure to a low adapting dose of radiation makes cells more resistant to the effects of a subsequent high dose exposure is termed radio-adaptive response. Adaptive response could hypothetically reduce the risk of late adverse effects of chronic or acute radiation exposures in humans. Understanding the underlying mechanisms of such responses is of relevance for radiation protection as well as for the clinical applications of radiation in medicine. However, due to the variability of responses depending on the model system and radiation condition, there is a need to further study under what conditions adaptive response can be induced. In this study, we analyzed if there is a dose rate dependence for the adapting dose, assuming that the adapting dose induces DNA response/repair pathways that are dose rate dependent. MCF-10A cells were exposed to a 50 mGy adapting dose administered acutely (0.40 Gy/min) or chronically (1.4 mGy/h or 4.1 mGy/h) and then irradiated by high acute challenging doses. The endpoints of study include clonogenic cell survival and mutation frequency at X-linked hprt locus. In another series of experiment, cells were exposed to 100 mGy and 1 Gy at different dose rates (acutely and chronically) and then the mutation frequencies were studied. Adaptive response was absent at the level of clonogenic survival. The mutation frequencies were significantly decreased in the cells pre-exposed to 50 mGy at 1.4 mGy/h followed by 1 Gy acute exposure as challenging dose. Importantly, at single dose exposures (1 Gy or 100 mGy), no differences at the level of mutation were found comparing different dose rates.

  20. Rates of morphological evolution in Captorhinidae: an adaptive radiation of Permian herbivores

    Directory of Open Access Journals (Sweden)

    Neil Brocklehurst

    2017-04-01

    Full Text Available The evolution of herbivory in early tetrapods was crucial in the establishment of terrestrial ecosystems, although it is so far unclear what effect this innovation had on the macro-evolutionary patterns observed within this clade. The clades that entered this under-filled region of ecospace might be expected to have experienced an “adaptive radiation”: an increase in rates of morphological evolution and speciation driven by the evolution of a key innovation. However such inferences are often circumstantial, being based on the coincidence of a rate shift with the origin of an evolutionary novelty. The conclusion of an adaptive radiation may be made more robust by examining the pattern of the evolutionary shift; if the evolutionary innovation coincides not only with a shift in rates of morphological evolution, but specifically in the morphological characteristics relevant to the ecological shift of interest, then one may more plausibly infer a causal relationship between the two. Here I examine the impact of diet evolution on rates of morphological change in one of the earliest tetrapod clades to evolve high-fibre herbivory: Captorhinidae. Using a method of calculating heterogeneity in rates of discrete character change across a phylogeny, it is shown that a significant increase in rates of evolution coincides with the transition to herbivory in captorhinids. The herbivorous captorhinids also exhibit greater morphological disparity than their faunivorous relatives, indicating more rapid exploration of new regions of morphospace. As well as an increase in rates of evolution, there is a shift in the regions of the skeleton undergoing the most change; the character changes in the herbivorous lineages are concentrated in the mandible and dentition. The fact that the increase in rates of evolution coincides with increased change in characters relating to food acquisition provides stronger evidence for a causal relationship between the herbivorous

  1. Effect of modeled microgravity on radiation-induced adaptive response of root growth in Arabidopsis thaliana

    International Nuclear Information System (INIS)

    Deng, Chenguang; Wang, Ting; Wu, Jingjing; Xu, Wei; Li, Huasheng; Liu, Min

    2017-01-01

    Highlights: • The radio-adaptive response (RAR) of A. thaliana root growth is modulated in microgravity. • The DNA damage repairs in RAR are regulated by microgravity. • The phytohormone auxin plays a regulatory role in the modulation of microgravity on RAR of root growth. - Abstract: Space particles have an inevitable impact on organisms during space missions; radio-adaptive response (RAR) is a critical radiation effect due to both low-dose background and sudden high-dose radiation exposure during solar storms. Although it is relevant to consider RAR within the context of microgravity, another major space environmental factor, there is no existing evidence as to its effects on RAR. In the present study, we established an experimental method for detecting the effects of gamma-irradiation on the primary root growth of Arabidopsis thaliana, in which RAR of root growth was significantly induced by several dose combinations. Microgravity was simulated using a two-dimensional rotation clinostat. It was shown that RAR of root growth was significantly inhibited under the modeled microgravity condition, and was absent in pgm-1 plants that had impaired gravity sensing in root tips. These results suggest that RAR could be modulated in microgravity. Time course analysis showed that microgravity affected either the development of radio-resistance induced by priming irradiation, or the responses of plants to challenging irradiation. After treatment with the modeled microgravity, attenuation in priming irradiation-induced expressions of DNA repair genes (AtKu70 and AtRAD54), and reduced DNA repair efficiency in response to challenging irradiation were observed. In plant roots, the polar transportation of the phytohormone auxin is regulated by gravity, and treatment with an exogenous auxin (indole-3-acetic acid) prevented the induction of RAR of root growth, suggesting that auxin might play a regulatory role in the interaction between microgravity and RAR of root growth.

  2. Positive diversifying selection is a pervasive adaptive force throughout the Drosophila radiation.

    Science.gov (United States)

    Cicconardi, Francesco; Marcatili, Paolo; Arthofer, Wolfgang; Schlick-Steiner, Birgit C; Steiner, Florian M

    2017-07-01

    The growing genomic information on non-model organisms eases exploring the evolutionary history of biodiversity. This is particularly true for Drosophila flies, in which the number of sequenced species doubled recently. Because of its outstanding diversity of species, Drosophila has become one of the most important systems to study adaptive radiation. In this study, we performed a genome-wide analysis of positive diversifying selection on more than 2000 single-copy orthologous groups in 25 species using a recent method of increased accuracy for detecting positive diversifying selection. Adopting this novel approach enabled us to find a consistent selection signal throughout the genus Drosophila, and a total of 1342 single-copy orthologous groups were identified with a putative signal of positive diversifying selection, corresponding to 1.9% of all loci. Specifically, in lineages leading to D. grimshawi, a strong putative signal of positive diversifying selection was found related to cell, morphological, neuronal, and sensorial development and function. A recurrent signal of positive diversifying selection was found on genes related to aging and lifespan, suggesting that selection had shaped lifespan diversity in Drosophila, including extreme longevity. Our study, one of the largest and most comprehensive ones on genome-wide positive diversifying selection to date, shows that positive diversifying selection has promoted species-specific differentiation among evolutionary lineages throughout the Drosophila radiation. Acting on the same biological processes via different routes, positive diversifying selection has promoted diversity of functions and adaptive divergence. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  3. Adaptation.

    Science.gov (United States)

    Broom, Donald M

    2006-01-01

    The term adaptation is used in biology in three different ways. It may refer to changes which occur at the cell and organ level, or at the individual level, or at the level of gene action and evolutionary processes. Adaptation by cells, especially nerve cells helps in: communication within the body, the distinguishing of stimuli, the avoidance of overload and the conservation of energy. The time course and complexity of these mechanisms varies. Adaptive characters of organisms, including adaptive behaviours, increase fitness so this adaptation is evolutionary. The major part of this paper concerns adaptation by individuals and its relationships to welfare. In complex animals, feed forward control is widely used. Individuals predict problems and adapt by acting before the environmental effect is substantial. Much of adaptation involves brain control and animals have a set of needs, located in the brain and acting largely via motivational mechanisms, to regulate life. Needs may be for resources but are also for actions and stimuli which are part of the mechanism which has evolved to obtain the resources. Hence pigs do not just need food but need to be able to carry out actions like rooting in earth or manipulating materials which are part of foraging behaviour. The welfare of an individual is its state as regards its attempts to cope with its environment. This state includes various adaptive mechanisms including feelings and those which cope with disease. The part of welfare which is concerned with coping with pathology is health. Disease, which implies some significant effect of pathology, always results in poor welfare. Welfare varies over a range from very good, when adaptation is effective and there are feelings of pleasure or contentment, to very poor. A key point concerning the concept of individual adaptation in relation to welfare is that welfare may be good or poor while adaptation is occurring. Some adaptation is very easy and energetically cheap and

  4. Replanning Criteria and Timing Definition for Parotid Protection-Based Adaptive Radiation Therapy in Nasopharyngeal Carcinoma

    Directory of Open Access Journals (Sweden)

    Wei-Rong Yao

    2015-01-01

    Full Text Available The goal of this study was to evaluate real-time volumetric and dosimetric changes of the parotid gland so as to determine replanning criteria and timing for parotid protection-based adaptive radiation therapy in nasopharyngeal carcinoma. Fifty NPC patients were treated with helical tomotherapy; volumetric and dosimetric (Dmean, V1, and D50 changes of the parotid gland at the 1st, 6th, 11th, 16th, 21st, 26th, 31st, and 33rd fractions were evaluated. The clinical parameters affecting these changes were studied by analyses of variance methods for repeated measures. Factors influencing the actual parotid dose were analyzed by a multivariate logistic regression model. The cut-off values predicting parotid overdose were developed from receiver operating characteristic curves and judged by combining them with a diagnostic test consistency check. The median absolute value and percentage of parotid volume reduction were 19.51 cm3 and 35%, respectively. The interweekly parotid volume varied significantly (p<0.05. The parotid Dmean, V1, and D50 increased by 22.13%, 39.42%, and 48.45%, respectively. The actual parotid dose increased by an average of 11.38% at the end of radiation therapy. Initial parotid volume, initial parotid Dmean, and weight loss rate are valuable indicators for parotid protection-based replanning.

  5. DNA sequence analysis of HPRT- mutants induced in human lymphoblastoid cells adapted to ionizing radiation

    International Nuclear Information System (INIS)

    Rigaud, O.; Laquerbe, A.; Moustacchi, E.

    1995-01-01

    Radioadaptation to the mutagenic effect of ionizing radiation by pre-exposure of human cells to a low dose has been shown to decrease the proportion of HPRT - mutants of the deletion type. To determine whether point mutations would be affected by the adaptive treatment, the molecular nature of mutations induced after exposure to low, high or low plus high doses was established. DNA sequencing of 38 point mutants which still expressed mRNA was performed using reverse transcription/polymerase chain reaction amplification. Under all conditions, base substitutions were the most common mutational event (range 72-80%), the remainder being frameshift and small deletions. The types and proportions of base changes did not appear to be differentially modified. A clustering of mutations was observed in exon 8, independently of the radiation protocol. About 40% of the mutants exhibited incorrect splicing of mRNA. The lack of striking modifications between the different molecular spectra of point mutations suggests that low-dose pre-exposure does not affect the production and/or the processing of lesions leading to point mutations. Thus the highly significant effect triggered by the low dose is the preferential reduction of deletion-type mutations. In view of the actual small data set, definitive conclusions will be drawn only when our observations are confirmed or can be generalized to human endogenous loci other than the HPRT locus, which is particularly prone to the recovery of deletion-type mutations. 37 refs., 1 fig., 5 tabs

  6. Adaptive statistical iterative reconstruction reduces patient radiation dose in neuroradiology CT studies.

    Science.gov (United States)

    Komlosi, Peter; Zhang, Yanrong; Leiva-Salinas, Carlos; Ornan, David; Patrie, James T; Xin, Wenjun; Grady, Deborah; Wintermark, Max

    2014-03-01

    Adaptive statistical iterative reconstruction (ASIR) can decrease image noise, thereby generating CT images of comparable diagnostic quality with less radiation. The purpose of this study is to quantify the effect of systematic use of ASIR versus filtered back projection (FBP) for neuroradiology CT protocols on patients' radiation dose and image quality. We evaluated the effect of ASIR on six types of neuroradiologic CT studies: adult and pediatric unenhanced head CT, adult cervical spine CT, adult cervical and intracranial CT angiography, adult soft tissue neck CT with contrast, and adult lumbar spine CT. For each type of CT study, two groups of 100 consecutive studies were retrospectively reviewed: 100 studies performed with FBP and 100 studies performed with ASIR/FBP blending factor of 40 %/60 % with appropriate noise indices. The weighted volume CT dose index (CTDIvol), dose-length product (DLP) and noise were recorded. Each study was also reviewed for image quality by two reviewers. Continuous and categorical variables were compared by t test and free permutation test, respectively. For adult unenhanced brain CT, CT cervical myelography, cervical and intracranial CT angiography and lumbar spine CT both CTDIvol and DLP were lowered by up to 10.9 % (p neuroradiology CT examinations because this approach affords a significant dose reduction while preserving image quality.

  7. Adaptive response induced by low doses of ionizing radiation in human lymphocytes

    International Nuclear Information System (INIS)

    Frati, Diego Libkind; Bunge, Maria M.

    2001-01-01

    The term adaptive response (AR) applies to the phenomenon of protection or enhanced repair induced by a small dose of a mutagenic agent. In order to determine the existence of AR in human lymphocytes for two different irradiation schemes, microcultures of blood from 4 donors were irradiated. Samples were exposed 24 hours (hr) after phytohemagglutinin stimulation to an adapting dose of 0,01 Gy and to a challenging dose of 1,5 Gy either 6 or 24 hr later (irradiation scheme 24+30 or 24+48, respectively). Gamma radiation from a 2,5 MeV Linac was used in all experiments. A cytogenetic analysis of unstable chromosome aberrations was applied as the endpoint. High inter-individual variability was found for the first irradiation scheme: one expressed AR, two did not and the last showed an apparent synergistic response. For the second irradiation scheme, low mitotic indices (MI) were found, suggesting a G2 arrest. When a series of harvesting times were applied for the last donor, normal MI were obtained only harvesting after 58 hr. An AR was found when harvesting at 72 hr but not at 58 hr. (author)

  8. Automatic Segmentation and Online virtualCT in Head-and-Neck Adaptive Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Peroni, Marta, E-mail: marta.peroni@mail.polimi.it [Department of Bioengineering, Politecnico di Milano, Milano (Italy); Ciardo, Delia [Advanced Radiotherapy Center, European Institute of Oncology, Milano (Italy); Spadea, Maria Francesca [Department of Experimental and Clinical Medicine, Universita degli Studi Magna Graecia, Catanzaro (Italy); Riboldi, Marco [Department of Bioengineering, Politecnico di Milano, Milano (Italy); Bioengineering Unit, Centro Nazionale di Adroterapia Oncologica, Pavia (Italy); Comi, Stefania; Alterio, Daniela [Advanced Radiotherapy Center, European Institute of Oncology, Milano (Italy); Baroni, Guido [Department of Bioengineering, Politecnico di Milano, Milano (Italy); Bioengineering Unit, Centro Nazionale di Adroterapia Oncologica, Pavia (Italy); Orecchia, Roberto [Advanced Radiotherapy Center, European Institute of Oncology, Milano (Italy); Universita degli Studi di Milano, Milano (Italy); Medical Department, Centro Nazionale di Adroterapia Oncologica, Pavia (Italy)

    2012-11-01

    Purpose: The purpose of this work was to develop and validate an efficient and automatic strategy to generate online virtual computed tomography (CT) scans for adaptive radiation therapy (ART) in head-and-neck (HN) cancer treatment. Method: We retrospectively analyzed 20 patients, treated with intensity modulated radiation therapy (IMRT), for an HN malignancy. Different anatomical structures were considered: mandible, parotid glands, and nodal gross tumor volume (nGTV). We generated 28 virtualCT scans by means of nonrigid registration of simulation computed tomography (CTsim) and cone beam CT images (CBCTs), acquired for patient setup. We validated our approach by considering the real replanning CT (CTrepl) as ground truth. We computed the Dice coefficient (DSC), center of mass (COM) distance, and root mean square error (RMSE) between correspondent points located on the automatically segmented structures on CBCT and virtualCT. Results: Residual deformation between CTrepl and CBCT was below one voxel. Median DSC was around 0.8 for mandible and parotid glands, but only 0.55 for nGTV, because of the fairly homogeneous surrounding soft tissues and of its small volume. Median COM distance and RMSE were comparable with image resolution. No significant correlation between RMSE and initial or final deformation was found. Conclusion: The analysis provides evidence that deformable image registration may contribute significantly in reducing the need of full CT-based replanning in HN radiation therapy by supporting swift and objective decision-making in clinical practice. Further work is needed to strengthen algorithm potential in nGTV localization.

  9. Spatially adaptive radiation-hydrodynamical simulations of galaxy formation during cosmological reionization

    Science.gov (United States)

    Pawlik, Andreas H.; Schaye, Joop; Dalla Vecchia, Claudio

    2015-08-01

    We present a suite of cosmological radiation-hydrodynamical simulations of the assembly of galaxies driving the reionization of the intergalactic medium (IGM) at z ≳ 6. The simulations account for the hydrodynamical feedback from photoionization heating and the explosion of massive stars as supernovae (SNe). Our reference simulation, which was carried out in a box of size 25 h-1 comovingMpc using 2 × 5123 particles, produces a reasonable reionization history and matches the observed UV luminosity function of galaxies. Simulations with different box sizes and resolutions are used to investigate numerical convergence, and simulations in which either SNe or photoionization heating or both are turned off, are used to investigate the role of feedback from star formation. Ionizing radiation is treated using accurate radiative transfer at the high spatially adaptive resolution at which the hydrodynamics is carried out. SN feedback strongly reduces the star formation rates (SFRs) over nearly the full mass range of simulated galaxies and is required to yield SFRs in agreement with observations. Photoheating helps to suppress star formation in low-mass galaxies, but its impact on the cosmic SFR is small. Because the effect of photoheating is masked by the strong SN feedback, it does not imprint a signature on the UV galaxy luminosity function, although we note that our resolution is insufficient to model star-forming minihaloes cooling through molecular hydrogen transitions. Photoheating does provide a strong positive feedback on reionization because it smooths density fluctuations in the IGM, which lowers the IGM recombination rate substantially. Our simulations demonstrate a tight non-linear coupling of galaxy formation and reionization, motivating the need for the accurate and simultaneous inclusion of photoheating and SN feedback in models of the early Universe.

  10. Radiation treatment for the right naris in a pediatric anesthesia patient using an adaptive oral airway technique

    Energy Technology Data Exchange (ETDEWEB)

    Sponseller, Patricia, E-mail: sponselp@uw.edu; Pelly, Nicole; Trister, Andrew; Ford, Eric; Ermoian, Ralph

    2015-10-01

    Radiation therapy for pediatric patients often includes the use of intravenous anesthesia with supplemental oxygen delivered via the nasal cannula. Here, we describe the use of an adaptive anesthesia technique for electron irradiation of the right naris in a preschool-aged patient treated under anesthesia. The need for an intranasal bolus plug precluded the use of standard oxygen supplementation. This novel technique required the multidisciplinary expertise of anesthesiologists, radiation therapists, medical dosimetrists, medical physicists, and radiation oncologists to ensure a safe and reproducible treatment course.

  11. Radiation treatment for the right naris in a pediatric anesthesia patient using an adaptive oral airway technique

    International Nuclear Information System (INIS)

    Sponseller, Patricia; Pelly, Nicole; Trister, Andrew; Ford, Eric; Ermoian, Ralph

    2015-01-01

    Radiation therapy for pediatric patients often includes the use of intravenous anesthesia with supplemental oxygen delivered via the nasal cannula. Here, we describe the use of an adaptive anesthesia technique for electron irradiation of the right naris in a preschool-aged patient treated under anesthesia. The need for an intranasal bolus plug precluded the use of standard oxygen supplementation. This novel technique required the multidisciplinary expertise of anesthesiologists, radiation therapists, medical dosimetrists, medical physicists, and radiation oncologists to ensure a safe and reproducible treatment course

  12. Clinical Outcomes With Dose-Escalated Adaptive Radiation Therapy for Urinary Bladder Cancer: A Prospective Study

    International Nuclear Information System (INIS)

    Murthy, Vedang; Masodkar, Renuka; Kalyani, Nikhil; Mahantshetty, Umesh; Bakshi, Ganesh; Prakash, Gagan; Joshi, Amit; Prabhash, Kumar; Ghonge, Sujata; Shrivastava, Shyamkishore

    2016-01-01

    Purpose: The purpose of this study was to assess feasibility, clinical outcomes, and toxicity in patients with bladder cancer treated with adaptive, image guided radiation therapy (IGRT) for bladder preservation as a part of trimodality treatment. The role of dose escalation was also studied. Methods and Materials: Forty-four patients with localized bladder cancer were enrolled in a prospective study. They underwent maximal safe resection of bladder tumor and concurrent platinum-based chemotherapy. Patients with large tumors were offered induction chemotherapy. Radiation therapy planning was done using either 3 (n=34) or 6 (n=10) concentrically grown planning target volumes (PTV). Patients received 64 Gy in 32 fractions to the whole bladder and 55 Gy to the pelvic nodes and, if appropriate, a simultaneous integrated boost to the tumor bed to 68 Gy (equivalent dose for 2-Gy fractions assuming α/β of 10 [EQD2] 10  = 68.7 Gy). Daily megavoltage (MV) imaging helped to choose the most appropriate PTV encompassing bladder for the particular day (using plan-of-the-day approach). Results: Most patients (88%) had T2 disease. Sixteen patients (36%) received neoadjuvant chemotherapy. A majority of the patients (73%) received prophylactic nodal irradiation, whereas 55% of the patients received escalated dose to the tumor bed. With a median follow-up of 30 months, the 3-year locoregional control (LRC), disease-free survival, and overall survival (OS) were 78%, 66%, and 67%, respectively. The bladder preservation rate was 83%. LRC (87% vs 68%, respectively, P=.748) and OS (74% vs 60%, respectively, P=.36) rates were better in patients receiving dose escalation. Instances of acute and late Radiation Therapy Oncology Group (RTOG) grade 3 genitourinary toxicity was seen in 5 (11%) and 2 (4%) patients, respectively. There was no acute or late RTOG grade 3 or higher gastrointestinal toxicity. Conclusions: Adaptive IGRT using plan-of-the-day approach for bladder preservation

  13. Proteomic study on X-irradiation-responsive proteins and ageing. Search for responsible proteins for radiation adaptive response

    International Nuclear Information System (INIS)

    Miura, Yuri; Kano, Mayumi; Suzuki, Shozo; Endo, Tamao; Toda, Tosifusa; Yamada, Masaki; Nishine, Tsutomu; Urano, Shiro

    2007-01-01

    We investigated high- or low-dose irradiation-responsive proteins using proteomics on two-dimensional (2D) polyacrylamide gel electrophoresis (PAGE), and the effects of ageing on cell responses to radiation in variously aged rat astrocytes. After 5 Gy irradiation, the relative abundance of peroxiredoxin 2, an antioxidant enzyme, and latexin, an inhibitor of carboxypeptidase, increased. The induction of these proteins was suppressed by ageing, suggesting that the response to high-dose radiation decreased with ageing. The relative abundance of elongation factor 2 (EF-2) fragment increased 3 h and reduced 24 h after 0.1 Gy irradiation. Temporal enhancement of the EF-2 fragment due to low-dose irradiation was suppressed by ageing. Since radiation adaptive response in cultured astrocytes was observed 3 h but not 24 h after 0.1 Gy irradiation and suppressed by ageing as previously reported, alteration of the EF-2 fragment corresponded to the radiation adaptive response. We also examined phospho-protein profiles, resulting in the relative abundance of phospho-EF-1β and phospho-β-actin being altered by 0.1 Gy irradiation; however, ageing did not affect the alteration of phospho-EF-1β and phospho-β-actin, unlike the EF-2 fragment. The results suggested that the EF-2 fragment was a possible candidate for the protein responsible for the radiation adaptive response in cultured astrocytes. (author)

  14. Adaptation

    International Development Research Centre (IDRC) Digital Library (Canada)

    . Dar es Salaam. Durban. Bloemfontein. Antananarivo. Cape Town. Ifrane ... program strategy. A number of CCAA-supported projects have relevance to other important adaptation-related themes such as disaster preparedness and climate.

  15. Effect of low dose radiation in lymphocytes from children exposed to ionizing radiation after the Chernobyl accident. Cytogenetic, chromosome painting, GPA and adaptive response studies

    International Nuclear Information System (INIS)

    Padovani, L.; Appolloni, M.; Anzidei, P.; Spano, M.; Stronati, L.; Testa, A.; Mauro, F.

    1997-01-01

    The present study concerns the monitoring of some children coming from Byelorussian, Ukrainian and Russian republics, exposed to the fall-out, or to the initial acute dose of radiation with the aim of assessing the effects of ionizing radiation on human health and of verifying the persisting of chromosomal damage several years after the accident. Both structural chromosomes damage (conventional cytogenetic and chromosome painting) and molecular mutation (GPA) have been investigated, moreover the possible induction of an adaptive response has been tested. (author)

  16. Altered G{sub 1} checkpoint control determines adaptive survival responses to ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Boothman, David A.; Meyers, Mark; Odegaard, Eric; Wang, Meizhi [Department of Human Oncology, University of Wisconsin-Madison, Madison, WI (United States)

    1996-11-04

    Adaptive survival responses (ASRs) are observed when cells become more resistant to a high dose of a cytotoxic agent after repeated low dose exposures to that agent or another genotoxic agent. Confluent (G{sub 0}/G{sub 1}) human normal (GM2936B, GM2937A, AG2603, IMR-90), cancer-prone (XPV2359), and neoplastic (U1-Mel, HEp-2, HTB-152) cells were primed with repeated low doses of X-rays (ranging from 0.05-10 cGy/day for 4 days), then challenged with a high dose (290-450 cGy) on day 5. U1-Mel and HEp-2 cells showed greater than 2-fold transient survival enhancement when primed with 1-10 cGy. ASRs in U1-Mel or HEp-2 cells were blocked by cycloheximide or actinomycin D. Increases in cyclins A and D1 mRNAs were noted in primed compared to unirradiated U1-Mel and HEp-2 cells; however, only cyclin A protein levels increased. Cyclin D1 and proliferating cell nuclear antigen (PCNA) protein levels were constitutively elevated in HEp-2 and U1-Mel cells, compared to the other human normal and neoplastic cells examined, and were not altered by low or high doses of radiation. Low dose primed U1-Mel cells entered S-phase 4-6 h faster than unprimed U1-Mel cells upon low-density replating. Similar responses in terms of survival recovery, transcript and protein induction, and altered cell cycle regulation were not observed in the other human normal, cancer-prone or neoplastic cells examined. We hypothesize that only certain human cells can adapt to ionizing radiation by progressing to a point later in G{sub 1} (the A point) where DNA repair processes and radioresistance can be induced. ASRs in human cells correlated well with constitutively elevated levels of PCNA and cyclin D1, as well as inducibility of cyclin A. We propose that a protein complex composed of cyclin D1, PCNA, and possibly cyclin A may play a role in cell cycle regulation and DNA repair, which determine ASRs in human cells.

  17. Altered G1 checkpoint control determines adaptive survival responses to ionizing radiation

    International Nuclear Information System (INIS)

    Boothman, David A.; Meyers, Mark; Odegaard, Eric; Wang, Meizhi

    1996-01-01

    Adaptive survival responses (ASRs) are observed when cells become more resistant to a high dose of a cytotoxic agent after repeated low dose exposures to that agent or another genotoxic agent. Confluent (G 0 /G 1 ) human normal (GM2936B, GM2937A, AG2603, IMR-90), cancer-prone (XPV2359), and neoplastic (U1-Mel, HEp-2, HTB-152) cells were primed with repeated low doses of X-rays (ranging from 0.05-10 cGy/day for 4 days), then challenged with a high dose (290-450 cGy) on day 5. U1-Mel and HEp-2 cells showed greater than 2-fold transient survival enhancement when primed with 1-10 cGy. ASRs in U1-Mel or HEp-2 cells were blocked by cycloheximide or actinomycin D. Increases in cyclins A and D1 mRNAs were noted in primed compared to unirradiated U1-Mel and HEp-2 cells; however, only cyclin A protein levels increased. Cyclin D1 and proliferating cell nuclear antigen (PCNA) protein levels were constitutively elevated in HEp-2 and U1-Mel cells, compared to the other human normal and neoplastic cells examined, and were not altered by low or high doses of radiation. Low dose primed U1-Mel cells entered S-phase 4-6 h faster than unprimed U1-Mel cells upon low-density replating. Similar responses in terms of survival recovery, transcript and protein induction, and altered cell cycle regulation were not observed in the other human normal, cancer-prone or neoplastic cells examined. We hypothesize that only certain human cells can adapt to ionizing radiation by progressing to a point later in G 1 (the A point) where DNA repair processes and radioresistance can be induced. ASRs in human cells correlated well with constitutively elevated levels of PCNA and cyclin D1, as well as inducibility of cyclin A. We propose that a protein complex composed of cyclin D1, PCNA, and possibly cyclin A may play a role in cell cycle regulation and DNA repair, which determine ASRs in human cells

  18. Reducing the radiation dose for CT colonography using adaptive statistical iterative reconstruction: A pilot study.

    Science.gov (United States)

    Flicek, Kristina T; Hara, Amy K; Silva, Alvin C; Wu, Qing; Peter, Mary B; Johnson, C Daniel

    2010-07-01

    The purpose of our study was to evaluate the feasibility of preserving image quality during CT colonography (CTC) using a reduced radiation dose with adaptive statistical iterative reconstruction (ASIR). A proven colon phantom was imaged at standard dose settings (50 mAs) and at reduced doses (10-40 mAs) using six different ASIR levels (0-100%). We assessed 2D and 3D image quality and noise to determine the optimal dose and ASIR setting. Eighteen patients were then scanned with a standard CTC dose (50 mAs) in the supine position and at a reduced dose of 25 mAs with 40% ASIR in the prone position. Three radiologists blinded to the scanning techniques assessed 2D and 3D image quality and noise at three different colon locations. A score difference of > or = 1 was considered clinically important. Actual noise measures were compared between the standard-dose and low-dose acquisitions. The phantom study showed image noise reduction that correlated with a higher percentage of ASIR. In patients, no significant image quality differences were identified between standard- and low-dose images using 40% ASIR. Overall image quality was reduced for both image sets as body mass index increased. Measured image noise was less with the low-dose technique using ASIR. The results of this pilot study show that the radiation dose during CTC can be reduced 50% below currently accepted low-dose techniques without significantly affecting image quality when ASIR is used. Further evaluation in a larger patient group is warranted.

  19. Adaptive Radiation in Socially Advanced Stem-Group Ants from the Cretaceous.

    Science.gov (United States)

    Barden, Phillip; Grimaldi, David A

    2016-02-22

    Across terrestrial ecosystems, modern ants are ubiquitous. As many as 94 out of every 100 individual arthropods in rainforests are ants, and they constitute up to 15% of animal biomass in the Amazon. Moreover, ants are pervasive agents of natural selection as over 10,000 arthropod species are specialized inquilines or myrmecomorphs living among ants or defending themselves through mimicry. Such impact is traditionally explained by sociality: ants are the first major group of ground-dwelling predatory insects to become eusocial, increasing efficiency of tasks and establishing competitive superiority over solitary species. A wealth of specimens from rich deposits of 99 million-year-old Burmese amber resolves ambiguity regarding sociality and diversity in the earliest ants. The stem-group genus Gerontoformica maintained distinct reproductive castes including morphotypes unknown in solitary aculeate (stinging) wasps, providing insight into early behavior. We present rare aggregations of workers, indicating group recruitment as well as an instance of interspecific combat; such aggression is a social feature of modern ants. Two species and an unusual new genus are described, further expanding the remarkable diversity of early ants. Stem-group ants are recovered as a paraphyletic assemblage at the base of modern lineages varying greatly in size, form, and mouthpart structure, interpreted here as an adaptive radiation. Though Cretaceous stem-group ants were eusocial and adaptively diverse, we hypothesize that their extinction resulted from the rise of competitively superior crown-group taxa that today form massive colonies, consistent with Wilson and Hölldobler's concept of "dynastic succession." Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Experimental Evolution of UV-C Radiation Tolerance: Emergence of Adaptive and Non-Adaptive Traits in Escherichia coli Under Differing Flux Regimes

    Science.gov (United States)

    Moffet, A.; Okansinski, A.; Sloan, C.; Grace, J. M.; Paulino-Lima, I. G.; Gentry, D.; Rothschild, L. J.; Camps, M.

    2014-12-01

    High-energy ultraviolet (UV-C) radiation is a significant challenge to life in environments such as high altitude areas, the early Earth, the Martian surface, and space. As UV-C exposure is both a selection pressure and a mutagen, adaptation dynamics in such environments include a high rate of change in both tolerance-related and non-tolerance-related genes, as well changes in linkages between the resulting traits. Determining the relationship between the intensity and duration of the UV-C exposure, mutation rate, and emergence of UV-C resistance will inform our understanding of both the emergence of radiation-related extremophily in natural environments and the optimal strategies for generating artificial extremophiles. In this study, we iteratively exposed an Escherichia colistrain to UV-C radiation of two different fluxes, 3.3 J/m^2/s for 6 seconds and 0.5 J/m^2/s for 40 seconds, with the same overall fluence of 20 J/m^2. After each iteration, cells from each exposure regime were assayed for increased UV-C tolerance as an adaptive trait. The exposed cells carried a plasmid bearing a TEM beta-lactamase gene, which in the absence of antibiotic treatment is a neutral reporter for mutagenesis. Sequencing of this gene allowed us to determine the baseline mutation frequency for each flux. As an additional readout for adaptation, the presence of extended-spectrum beta-lactamase mutations was tested by plating UV-exposed cultures in cefotaxime plates. We observed an increase of approximately one-million-fold in UV-C tolerance over seven iterations; no significant difference between the two fluxes was found. Future work will focus on identifying the genomic changes responsible for the change in UV-C tolerance; determining the mechanisms of the emerged UV-C tolerance; and performing competition experiments between the iteration strains to quantify fitness tradeoffs resulting from UV-C adaptation.

  1. Adapt

    Science.gov (United States)

    Bargatze, L. F.

    2015-12-01

    Active Data Archive Product Tracking (ADAPT) is a collection of software routines that permits one to generate XML metadata files to describe and register data products in support of the NASA Heliophysics Virtual Observatory VxO effort. ADAPT is also a philosophy. The ADAPT concept is to use any and all available metadata associated with scientific data to produce XML metadata descriptions in a consistent, uniform, and organized fashion to provide blanket access to the full complement of data stored on a targeted data server. In this poster, we present an application of ADAPT to describe all of the data products that are stored by using the Common Data File (CDF) format served out by the CDAWEB and SPDF data servers hosted at the NASA Goddard Space Flight Center. These data servers are the primary repositories for NASA Heliophysics data. For this purpose, the ADAPT routines have been used to generate data resource descriptions by using an XML schema named Space Physics Archive, Search, and Extract (SPASE). SPASE is the designated standard for documenting Heliophysics data products, as adopted by the Heliophysics Data and Model Consortium. The set of SPASE XML resource descriptions produced by ADAPT includes high-level descriptions of numerical data products, display data products, or catalogs and also includes low-level "Granule" descriptions. A SPASE Granule is effectively a universal access metadata resource; a Granule associates an individual data file (e.g. a CDF file) with a "parent" high-level data resource description, assigns a resource identifier to the file, and lists the corresponding assess URL(s). The CDAWEB and SPDF file systems were queried to provide the input required by the ADAPT software to create an initial set of SPASE metadata resource descriptions. Then, the CDAWEB and SPDF data repositories were queried subsequently on a nightly basis and the CDF file lists were checked for any changes such as the occurrence of new, modified, or deleted

  2. Interval for the expression of the adaptive response induced by gamma radiation in leucocytes of mouse In vivo

    International Nuclear Information System (INIS)

    Mendiola C, M.T.; Morales R, P.

    2002-01-01

    The interval between the adaptive gamma radiation dose (0.01 Gy) and challenge (1.0 Gy) capable to induce the maximum expression of the adaptive response in lymphocytes of mouse In vivo. The animals were exposed to the mentioned doses with different intervals among both (1, 1.5, 5 or 18 hr). By means of the unicellular electrophoresis in gel technique, four damage parameters were analysed. The results showed that from the 1 hr interval an adaptive response was produced since in the pretreated organisms with 0.01 Gy the cells present lesser damage than in those not adapted. The maximum response was induced with the intervals between 2.5 and 5 hr and even though it persisted until 18 hr, the effect was reducing. (Author)

  3. Evidence for determinism in species diversification and contingency in phenotypic evolution during adaptive radiation.

    Science.gov (United States)

    Burbrink, Frank T; Chen, Xin; Myers, Edward A; Brandley, Matthew C; Pyron, R Alexander

    2012-12-07

    Adaptive radiation (AR) theory predicts that groups sharing the same source of ecological opportunity (EO) will experience deterministic species diversification and morphological evolution. Thus, deterministic ecological and morphological evolution should be correlated with deterministic patterns in the tempo and mode of speciation for groups in similar habitats and time periods. We test this hypothesis using well-sampled phylogenies of four squamate groups that colonized the New World (NW) in the Late Oligocene. We use both standard and coalescent models to assess species diversification, as well as likelihood models to examine morphological evolution. All squamate groups show similar early pulses of speciation, as well as diversity-dependent ecological limits on clade size at a continental scale. In contrast, processes of morphological evolution are not easily predictable and do not show similar pulses of early and rapid change. Patterns of morphological and species diversification thus appear uncoupled across these groups. This indicates that the processes that drive diversification and disparification are not mechanistically linked, even among similar groups of taxa experiencing the same sources of EO. It also suggests that processes of phenotypic diversification cannot be predicted solely from the existence of an AR or knowledge of the process of diversification.

  4. Iterative development and the scope for plasticity: contrasts among trait categories in an adaptive radiation.

    Science.gov (United States)

    Foster, S A; Wund, M A; Graham, M A; Earley, R L; Gardiner, R; Kearns, T; Baker, J A

    2015-10-01

    Phenotypic plasticity can influence evolutionary change in a lineage, ranging from facilitation of population persistence in a novel environment to directing the patterns of evolutionary change. As the specific nature of plasticity can impact evolutionary consequences, it is essential to consider how plasticity is manifested if we are to understand the contribution of plasticity to phenotypic evolution. Most morphological traits are developmentally plastic, irreversible, and generally considered to be costly, at least when the resultant phenotype is mis-matched to the environment. At the other extreme, behavioral phenotypes are typically activational (modifiable on very short time scales), and not immediately costly as they are produced by constitutive neural networks. Although patterns of morphological and behavioral plasticity are often compared, patterns of plasticity of life history phenotypes are rarely considered. Here we review patterns of plasticity in these trait categories within and among populations, comprising the adaptive radiation of the threespine stickleback fish Gasterosteus aculeatus. We immediately found it necessary to consider the possibility of iterated development, the concept that behavioral and life history trajectories can be repeatedly reset on activational (usually behavior) or developmental (usually life history) time frames, offering fine tuning of the response to environmental context. Morphology in stickleback is primarily reset only in that developmental trajectories can be altered as environments change over the course of development. As anticipated, the boundaries between the trait categories are not clear and are likely to be linked by shared, underlying physiological and genetic systems.

  5. Convergent evolution of behavior in an adaptive radiation of Hawaiian web-building spiders.

    Science.gov (United States)

    Blackledge, Todd A; Gillespie, Rosemary G

    2004-11-16

    Species in ecologically similar habitats often display patterns of divergence that are strikingly comparable, suggesting that natural selection can lead to predictable evolutionary change in communities. However, the relative importance of selection as an agent mediating in situ diversification, versus dispersal between habitats, cannot be addressed without knowledge of phylogenetic history. We used an adaptive radiation of spiders within the Hawaiian Islands to test the prediction that species of spiders on different islands would independently evolve webs with similar architectures. Tetragnatha spiders are the only nocturnal orb-weaving spiders endemic to the Hawaiian archipelago, and multiple species of orb-weaving Tetragnatha co-occur within mesic and wet forest habitats on each of the main islands. Therefore, comparison of web architectures spun by spiders on different islands allowed study of replicated evolutionary events of past behavioral diversification. We found that species within each island construct webs with architectures that differ from one another. However, pairs of species on different islands, "ethotypes," share remarkable similarities in web architectures. Phylogenetic analysis demonstrated that the species comprising these ethotypes evolved independent of one another. Our study illustrates the high degree of predictability that can be exhibited by the evolutionary diversification of complex behaviors. However, not all web architectures were shared between islands, demonstrating that unique effects also have played an important role in the historical diversification of behavior.

  6. Adaptation

    International Development Research Centre (IDRC) Digital Library (Canada)

    Nairobi, Kenya. 28 Adapting Fishing Policy to Climate Change with the Aid of Scientific and Endogenous Knowledge. Cap Verde, Gambia,. Guinea, Guinea Bissau,. Mauritania and Senegal. Environment and Development in the Third World. (ENDA-TM). Dakar, Senegal. 29 Integrating Indigenous Knowledge in Climate Risk ...

  7. Mutagenic adaptive response to high-LET radiation in human lymphoblastoid cells exposed to low doses of heavy-ion radiation

    Energy Technology Data Exchange (ETDEWEB)

    Vares, Guillaume, E-mail: vares@nirs.go.jp [Radiation Risk Reduction Research Program, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage-ku, Chiba 263-8555 (Japan); Wang, Bing, E-mail: jp2813km@nirs.go.jp [Radiation Risk Reduction Research Program, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage-ku, Chiba 263-8555 (Japan); Tanaka, Kaoru; Kakimoto, Ayana; Eguchi-Kasai, Kyomi; Nenoi, Mitsuru [Radiation Risk Reduction Research Program, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage-ku, Chiba 263-8555 (Japan)

    2011-07-01

    Adaptive response (AR) and bystander effect are two important phenomena involved in biological responses to low doses of ionizing radiation (IR). Furthermore, there is a strong interest in better understanding the biological effects of high-LET radiation. We previously demonstrated the ability of low doses of X-rays to induce an AR to challenging heavy-ion radiation . In this study, we assessed in vitro the ability of priming low doses (0.01 Gy) of heavy-ion radiation to induce a similar AR to a subsequent challenging dose (1-4 Gy) of high-LET IR (carbon-ion: 20 and 40 keV/{mu}m, neon-ion: 150 keV/{mu}m) in TK6, AHH-1 and NH32 cells. Our results showed that low doses of high-LET radiation can induce an AR characterized by lower mutation frequencies at hypoxanthine-guanine phosphoribosyl transferase locus and faster DNA repair kinetics, in cells expressing p53.

  8. Integration of on-line imaging, plan adaptation and radiation delivery: proof of concept using digital tomosynthesis

    International Nuclear Information System (INIS)

    Mestrovic, Ante; Otto, Karl; Nichol, Alan; Clark, Brenda G

    2009-01-01

    The main objective of this manuscript is to propose a new approach to on-line adaptive radiation therapy (ART) in which daily image acquisition, plan adaptation and radiation delivery are integrated together and performed concurrently. A method is described in which on-line ART is performed based on intra-fractional digital tomosynthesis (DTS) images. Intra-fractional DTS images were reconstructed as the gantry rotated between treatment positions. An edge detection algorithm was used to automatically segment the DTS images as the gantry arrived at each treatment position. At each treatment position, radiation was delivered based on the treatment plan re-optimized for the most recent DTS image contours. To investigate the feasibility of this method, a model representing a typical prostate, bladder and rectum was used. To simulate prostate deformations, three clinically relevant, non-rigid deformations (small, medium and large) were modeled by systematically deforming the original anatomy. Using our approach to on-line ART, the original treatment plan was successfully adapted to arrive at a clinically acceptable plan for all three non-rigid deformations. In conclusion, we have proposed a new approach to on-line ART in which plan adaptation is performed based on intra-fractional DTS images. The study findings indicate that this approach can be used to re-optimize the original treatment plan to account for non-rigid anatomical deformations. The advantages of this approach are 1) image acquisition and radiation delivery are integrated in a single gantry rotation around the patient, reducing the treatment time, and 2) intra-fractional DTS images can be used to detect and correct for patient motion prior to the delivery of each beam (intra-fractional patient motion).

  9. GAMMA-RAY BURST DYNAMICS AND AFTERGLOW RADIATION FROM ADAPTIVE MESH REFINEMENT, SPECIAL RELATIVISTIC HYDRODYNAMIC SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    De Colle, Fabio; Ramirez-Ruiz, Enrico [Astronomy and Astrophysics Department, University of California, Santa Cruz, CA 95064 (United States); Granot, Jonathan [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Lopez-Camara, Diego, E-mail: fabio@ucolick.org [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ap. 70-543, 04510 D.F. (Mexico)

    2012-02-20

    We report on the development of Mezcal-SRHD, a new adaptive mesh refinement, special relativistic hydrodynamics (SRHD) code, developed with the aim of studying the highly relativistic flows in gamma-ray burst sources. The SRHD equations are solved using finite-volume conservative solvers, with second-order interpolation in space and time. The correct implementation of the algorithms is verified by one-dimensional (1D) and multi-dimensional tests. The code is then applied to study the propagation of 1D spherical impulsive blast waves expanding in a stratified medium with {rho}{proportional_to}r{sup -k}, bridging between the relativistic and Newtonian phases (which are described by the Blandford-McKee and Sedov-Taylor self-similar solutions, respectively), as well as to a two-dimensional (2D) cylindrically symmetric impulsive jet propagating in a constant density medium. It is shown that the deceleration to nonrelativistic speeds in one dimension occurs on scales significantly larger than the Sedov length. This transition is further delayed with respect to the Sedov length as the degree of stratification of the ambient medium is increased. This result, together with the scaling of position, Lorentz factor, and the shock velocity as a function of time and shock radius, is explained here using a simple analytical model based on energy conservation. The method used for calculating the afterglow radiation by post-processing the results of the simulations is described in detail. The light curves computed using the results of 1D numerical simulations during the relativistic stage correctly reproduce those calculated assuming the self-similar Blandford-McKee solution for the evolution of the flow. The jet dynamics from our 2D simulations and the resulting afterglow light curves, including the jet break, are in good agreement with those presented in previous works. Finally, we show how the details of the dynamics critically depend on properly resolving the structure of the

  10. Adaptive radiation, correlated and contingent evolution, and net species diversification in Bromeliaceae.

    Science.gov (United States)

    Givnish, Thomas J; Barfuss, Michael H J; Van Ee, Benjamin; Riina, Ricarda; Schulte, Katharina; Horres, Ralf; Gonsiska, Philip A; Jabaily, Rachel S; Crayn, Darren M; Smith, J Andrew C; Winter, Klaus; Brown, Gregory K; Evans, Timothy M; Holst, Bruce K; Luther, Harry; Till, Walter; Zizka, Georg; Berry, Paul E; Sytsma, Kenneth J

    2014-02-01

    We present an integrative model predicting associations among epiphytism, the tank habit, entangling seeds, C₃ vs. CAM photosynthesis, avian pollinators, life in fertile, moist montane habitats, and net rates of species diversification in the monocot family Bromeliaceae. We test these predictions by relating evolutionary shifts in form, physiology, and ecology to time and ancestral distributions, quantifying patterns of correlated and contingent evolution among pairs of traits and analyzing the apparent impact of individual traits on rates of net species diversification and geographic expansion beyond the ancestral Guayana Shield. All predicted patterns of correlated evolution were significant, and the temporal and spatial associations of phenotypic shifts with orogenies generally accorded with predictions. Net rates of species diversification were most closely coupled to life in fertile, moist, geographically extensive cordilleras, with additional significant ties to epiphytism, avian pollination, and the tank habit. The highest rates of net diversification were seen in the bromelioid tank-epiphytic clade (D(crown) = 1.05 My⁻¹), associated primarily with the Serra do Mar and nearby ranges of coastal Brazil, and in the core tillandsioids (D(crown) = 0.67 My⁻¹), associated primarily with the Andes and Central America. Six large-scale adaptive radiations and accompanying pulses of speciation account for 86% of total species richness in the family. This study is among the first to test a priori hypotheses about the relationships among phylogeny, phenotypic evolution, geographic spread, and net species diversification, and to argue for causality to flow from functional diversity to spatial expansion to species diversity.

  11. Gamma-Ray Burst Dynamics and Afterglow Radiation from Adaptive Mesh Refinement, Special Relativistic Hydrodynamic Simulations

    Science.gov (United States)

    De Colle, Fabio; Granot, Jonathan; López-Cámara, Diego; Ramirez-Ruiz, Enrico

    2012-02-01

    We report on the development of Mezcal-SRHD, a new adaptive mesh refinement, special relativistic hydrodynamics (SRHD) code, developed with the aim of studying the highly relativistic flows in gamma-ray burst sources. The SRHD equations are solved using finite-volume conservative solvers, with second-order interpolation in space and time. The correct implementation of the algorithms is verified by one-dimensional (1D) and multi-dimensional tests. The code is then applied to study the propagation of 1D spherical impulsive blast waves expanding in a stratified medium with ρvpropr -k , bridging between the relativistic and Newtonian phases (which are described by the Blandford-McKee and Sedov-Taylor self-similar solutions, respectively), as well as to a two-dimensional (2D) cylindrically symmetric impulsive jet propagating in a constant density medium. It is shown that the deceleration to nonrelativistic speeds in one dimension occurs on scales significantly larger than the Sedov length. This transition is further delayed with respect to the Sedov length as the degree of stratification of the ambient medium is increased. This result, together with the scaling of position, Lorentz factor, and the shock velocity as a function of time and shock radius, is explained here using a simple analytical model based on energy conservation. The method used for calculating the afterglow radiation by post-processing the results of the simulations is described in detail. The light curves computed using the results of 1D numerical simulations during the relativistic stage correctly reproduce those calculated assuming the self-similar Blandford-McKee solution for the evolution of the flow. The jet dynamics from our 2D simulations and the resulting afterglow light curves, including the jet break, are in good agreement with those presented in previous works. Finally, we show how the details of the dynamics critically depend on properly resolving the structure of the relativistic flow.

  12. Modeling UV Radiation Feedback from Massive Stars. I. Implementation of Adaptive Ray-tracing Method and Tests

    Science.gov (United States)

    Kim, Jeong-Gyu; Kim, Woong-Tae; Ostriker, Eve C.; Skinner, M. Aaron

    2017-12-01

    We present an implementation of an adaptive ray-tracing (ART) module in the Athena hydrodynamics code that accurately and efficiently handles the radiative transfer involving multiple point sources on a three-dimensional Cartesian grid. We adopt a recently proposed parallel algorithm that uses nonblocking, asynchronous MPI communications to accelerate transport of rays across the computational domain. We validate our implementation through several standard test problems, including the propagation of radiation in vacuum and the expansions of various types of H II regions. Additionally, scaling tests show that the cost of a full ray trace per source remains comparable to that of the hydrodynamics update on up to ∼ {10}3 processors. To demonstrate application of our ART implementation, we perform a simulation of star cluster formation in a marginally bound, turbulent cloud, finding that its star formation efficiency is 12% when both radiation pressure forces and photoionization by UV radiation are treated. We directly compare the radiation forces computed from the ART scheme with those from the M 1 closure relation. Although the ART and M 1 schemes yield similar results on large scales, the latter is unable to resolve the radiation field accurately near individual point sources.

  13. Adaptive response of human lymphocytes to low dose radiation on DNA synthesis

    International Nuclear Information System (INIS)

    Du Zeji; Su Liaoyuan; Tian Hailin

    1995-01-01

    Human peripheral blood lymphocytes PHA-stimulated in vitro for 24 h were exposed to low dose γ-ray irradiation (adaptive dose), they showed an adaptive response to the inhibition of DNA synthesis by subsequent higher acute doses of γ-ray (challenge dose). At the interval of 24 h between adaptive dose and challenge dose, the most obvious adaptive response induced by low dose irradiation was found. It was also found that the response induced by 1.0 cGy of adaptive dose was more obvious than that by other doses. In the challenge doses range of 1.0∼7.0 Gy, the adaptive response was observed and that 3.0 Gy was more obvious. The adaptive response disappeared with the challenge doses further increased

  14. Adaptive Response to ionizing Radiation Induced by Low Doses of Gamma Rays in Human Lymphoblastoid Cell Lines

    International Nuclear Information System (INIS)

    Seong, Jin Sil; Suh, Chang Ok; Kim, Gwi Eon

    1994-01-01

    When cells are exposed to low doses of a mutagenic or clastogenic agents, they often become less sensitive to the effects of a higher does administered subsequently. Such adaptive responses were first described in Escherichia coli and mammalian cells to low doses of an alkylating agent. Since most of the studies have been carried out with human lymphocytes, it is urgently necessary to study this effect in different cellular systems. Its relation with inherent cellular radiosensitivity and underlying mechanism also remain to be answered. In this study, adaptive response by 1 cGy of gamma rays was investigated in three human lymphoblastoid cell lines which were derived from ataxia telangiectasia homozygote, ataxia telangiectasia heterozygote, and normal individual. Experiments were carried out by delivering 1 cGy followed by 50 cGy of gamma radiation and chromatid breaks were scored as an endpoint. The results indicate that prior exposure to 1 cGy of gamma rays reduces the number of chromatid breaks induced by subsequent higher does (50 cGy). The expression of this adaptive response was similar among three cell lines despite of their different radiosensitivity. When 3-aminobenzamide, an inhibitor of poly (ADP-ribose) polymerase, was added after 50 cGy, adaptive responses were abolished in all the tested cell lines. Therefore it is suggested that the adaptive response can be observed in human lymphoblastoid cell lines. Which was first documented through this study. The expression of adaptive response was similar among the cell lines regardless of their radiosensitivity. The elimination of the adaptive response by 3-aminobenzamide is consistent with the proposal that this adaptive response is the result of the induction of a certain chromosomal repair mechanism

  15. Radiation

    International Nuclear Information System (INIS)

    2013-01-01

    The chapter one presents the composition of matter and atomic theory; matter structure; transitions; origin of radiation; radioactivity; nuclear radiation; interactions in decay processes; radiation produced by the interaction of radiation with matter

  16. A review of segmentation and deformable registration methods applied to adaptive cervical cancer radiation therapy treatment planning.

    Science.gov (United States)

    Ghose, Soumya; Holloway, Lois; Lim, Karen; Chan, Philip; Veera, Jacqueline; Vinod, Shalini K; Liney, Gary; Greer, Peter B; Dowling, Jason

    2015-06-01

    Manual contouring and registration for radiotherapy treatment planning and online adaptation for cervical cancer radiation therapy in computed tomography (CT) and magnetic resonance images (MRI) are often necessary. However manual intervention is time consuming and may suffer from inter or intra-rater variability. In recent years a number of computer-guided automatic or semi-automatic segmentation and registration methods have been proposed. Segmentation and registration in CT and MRI for this purpose is a challenging task due to soft tissue deformation, inter-patient shape and appearance variation and anatomical changes over the course of treatment. The objective of this work is to provide a state-of-the-art review of computer-aided methods developed for adaptive treatment planning and radiation therapy planning for cervical cancer radiation therapy. Segmentation and registration methods published with the goal of cervical cancer treatment planning and adaptation have been identified from the literature (PubMed and Google Scholar). A comprehensive description of each method is provided. Similarities and differences of these methods are highlighted and the strengths and weaknesses of these methods are discussed. A discussion about choice of an appropriate method for a given modality is provided. In the reviewed papers a Dice similarity coefficient of around 0.85 along with mean absolute surface distance of 2-4mm for the clinically treated volume were reported for transfer of contours from planning day to the treatment day. Most segmentation and non-rigid registration methods have been primarily designed for adaptive re-planning for the transfer of contours from planning day to the treatment day. The use of shape priors significantly improved segmentation and registration accuracy compared to other models. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. The use of adaptive radiation therapy to reduce setup error: a prospective clinical study

    International Nuclear Information System (INIS)

    Yan Di; Wong, John; Vicini, Frank; Robertson, John; Horwitz, Eric; Brabbins, Donald; Cook, Carla; Gustafson, Gary; Stromberg, Jannifer; Martinez, Alvaro

    1996-01-01

    Purpose: Adaptive Radiation Therapy (ART) is a closed-loop feedback process where each patients treatment is adaptively optimized according to the individual variation information measured during the course of treatment. The process aims to maximize the benefits of treatment for the individual patient. A prospective study is currently being conducted to test the feasibility and effectiveness of ART for clinical use. The present study is limited to compensating the effects of systematic setup error. Methods and Materials: The study includes 20 patients treated on a linear accelerator equipped with a computer controlled multileaf collimator (MLC) and a electronic portal imaging device (EPID). Alpha cradles are used to immobilize those patients treated for disease in the thoracic and abdominal regions, and thermal plastic masks for the head and neck. Portal images are acquired daily. Setup error of each treatment field is quantified off-line every day. As determined from an earlier retrospective study of different clinical sites, the measured setup variation from the first 4 to 9 days, are used to estimate systematic setup error and the standard deviation of random setup error for each field. Setup adjustment is made if estimated systematic setup error of the treatment field was larger than or equal to 2 mm. Instead of the conventional approach of repositioning the patient, setup correction is implemented by reshaping MLC to compensate for the estimated systematic error. The entire process from analysis of portal images to the implementation of the modified MLC field is performed via computer network. Systematic and random setup errors of the treatment after adjustment are compared with those prior to adjustment. Finally, the frequency distributions of block overlap cumulated throughout the treatment course are evaluated. Results: Sixty-seven percent of all treatment fields were reshaped to compensate for the estimated systematic errors. At the time of this writing

  18. A unique mode of tissue oxygenation and the adaptive radiation of teleost fishes.

    Science.gov (United States)

    Randall, D J; Rummer, J L; Wilson, J M; Wang, S; Brauner, C J

    2014-04-15

    for CO2 hydration/dehydration. Finally, RBC organophosphates (e.g. NTP) could be reduced during hypoxia to further increase Hb-O2 affinity without compromising tissue O2 delivery because high-affinity Hbs could still adequately deliver O2 to the tissues via Bohr/Root shifts. We suggest that the evolution of this unique mode of tissue O2 transfer evolved in the Triassic/Jurassic Period, when O2 levels were low, ultimately giving rise to the most extensive adaptive radiation of extant vertebrates, the teleost fishes.

  19. An anthropomorphic abdominal phantom for deformable image registration accuracy validation in adaptive radiation therapy.

    Science.gov (United States)

    Liao, Yuliang; Wang, Linjing; Xu, Xiangdong; Chen, Haibin; Chen, Jiawei; Zhang, Guoqian; Lei, Huaiyu; Wang, Ruihao; Zhang, Shuxu; Gu, Xuejun; Zhen, Xin; Zhou, Linghong

    2017-06-01

    To design and construct a three-dimensional (3D) anthropomorphic abdominal phantom for geometric accuracy and dose summation accuracy evaluations of deformable image registration (DIR) algorithms for adaptive radiation therapy (ART). Organ molds, including liver, kidney, spleen, stomach, vertebra, and two metastasis tumors, were 3D printed using contours from an ovarian cancer patient. The organ molds were molded with deformable gels made of different mixtures of polyvinyl chloride (PVC) and the softener dioctyl terephthalate. Gels with different densities were obtained by a polynomial fitting curve that described the relation between the Hounsfield unit (HU) and PVC-softener blending ratio. The rigid vertebras were constructed by molding of white cement and cellulose pulp. The final abdominal phantom was assembled by arranging all the fabricated organs inside a hollow dummy according to their anatomies, and sealed by deformable gel with averaged HU of muscle and fat. Fiducial landmarks were embedded inside the phantom for spatial accuracy and dose accumulation accuracy studies. Two channels were excavated to facilitate ionization chamber insertion for dosimetric measurements. Phantom properties such as deformable gel elasticity and HU stability were studied. The dosimetric measurement accuracy in the phantom was performed, and the DIR accuracies of three DIR algorithms available in the open source DIR toolkit-DIRART were also validated. The constructed deformable gel showed elastic behavior and was stable in HU values over times, proving to be a practical material for the deformable phantom. The constructed abdominal phantom consisted of realistic anatomies in terms of both anatomical shapes and densities when compared with its reference patient. The dosimetric measurements showed a good agreement with the calculated doses from the treatment planning system. Fiducial-based accuracy analysis conducted on the constructed phantom demonstrated the feasibility of

  20. Radioadaptive response. Efficient repair of radiation-induced DNA damage in adapted cells

    International Nuclear Information System (INIS)

    Ikushima, Takaji; Aritomi, Hisako; Morisita, Jun

    1996-01-01

    To verify the hypothesis that the induction of a novel, efficient repair mechanism for chromosomal DNA breaks may be involved in the radioadaptive response, the repair kinetics of DNA damage has been studied in cultured Chinese hamster V79 cells with single-cell gel electrophoresis. The cells were adapted by priming exposure with 5 cGy of γ-rays and 4-h incubation at 37C. There were no indication of any difference in the initial yields of DNA double-strand breaks induced by challenging doses from non-adapted cells and from adapted cells. The rejoining of DNA double-strand breaks was monitored over 120 min after the adapted cells were challenged with 5 or 1.5 Gy, doses at the same level to those used in the cytogenetical adaptive response. The rate of DNA damage repair in adapted cells was higher than that in non-adapted cells, and the residual damage was less in adapted cells than in non-adapted cells. These results indicate that the radioadaptive response may result from the induction of a novel, efficient DNA repair mechanism which leads to less residual damage, but not from the induction of protective functions that reduce the initial DNA damage

  1. A 5-Year Investigation of Children's Adaptive Functioning Following Conformal Radiation Therapy for Localized Ependymoma

    Energy Technology Data Exchange (ETDEWEB)

    Netson, Kelli L.; Conklin, Heather M. [Department of Psychology, St. Jude Children' s Research Hospital, Memphis, Tennessee (United States); Wu Shengjie; Xiong Xiaoping [Department of Biostatistics, St. Jude Children' s Research Hospital, Memphis, Tennessee (United States); Merchant, Thomas E., E-mail: thomas.merchant@stjude.org [Division of Radiation Oncology, St. Jude Children' s Research Hospital, Memphis, Tennessee (United States)

    2012-09-01

    Purpose: Conformal and intensity modulated radiation therapies have the potential to preserve cognitive outcomes in children with ependymoma; however, functional behavior remains uninvestigated. This longitudinal investigation prospectively examined intelligence quotient (IQ) and adaptive functioning during the first 5 years after irradiation in children diagnosed with ependymoma. Methods and Materials: The study cohort consisted of 123 children with intracranial ependymoma. Mean age at irradiation was 4.60 years (95% confidence interval [CI], 3.85-5.35). Serial neurocognitive evaluations, including an age-appropriate IQ measure and the Vineland Adaptive Behavior Scales (VABS), were completed before irradiation, 6 months after treatment, and annually for 5 years. A total of 579 neurocognitive evaluations were included in these analyses. Results: Baseline IQ and VABS were below normative means (P<.05), although within the average range. Linear mixed models revealed stable IQ and VABS across the follow-up period, except for the VABS Communication Index, which declined significantly (P=.015). Annual change in IQ (-.04 points) did not correlate with annual change in VABS (-.90 to +.44 points). Clinical factors associated with poorer baseline performance (P<.05) included preirradiation chemotherapy, cerebrospinal fluid shunt placement, number and extent of surgical resections, and younger age at treatment. No clinical factors significantly affected the rate of change in scores. Conclusions: Conformal and intensity modulated radiation therapies provided relative sparing of functional outcomes including IQ and adaptive behaviors, even in very young children. Communication skills remained vulnerable and should be the target of preventive and rehabilitative interventions.

  2. Comparative genomics of Thermus thermophilus and Deinococcus radiodurans: divergent routes of adaptation to thermophily and radiation resistance

    Directory of Open Access Journals (Sweden)

    Daly Michael J

    2005-10-01

    Full Text Available Abstract Background Thermus thermophilus and Deinococcus radiodurans belong to a distinct bacterial clade but have remarkably different phenotypes. T. thermophilus is a thermophile, which is relatively sensitive to ionizing radiation and desiccation, whereas D. radiodurans is a mesophile, which is highly radiation- and desiccation-resistant. Here we present an in-depth comparison of the genomes of these two related but differently adapted bacteria. Results By reconstructing the evolution of Thermus and Deinococcus after the divergence from their common ancestor, we demonstrate a high level of post-divergence gene flux in both lineages. Various aspects of the adaptation to high temperature in Thermus can be attributed to horizontal gene transfer from archaea and thermophilic bacteria; many of the horizontally transferred genes are located on the single megaplasmid of Thermus. In addition, the Thermus lineage has lost a set of genes that are still present in Deinococcus and many other mesophilic bacteria but are not common among thermophiles. By contrast, Deinococcus seems to have acquired numerous genes related to stress response systems from various bacteria. A comparison of the distribution of orthologous genes among the four partitions of the Deinococcus genome and the two partitions of the Thermus genome reveals homology between the Thermus megaplasmid (pTT27 and Deinococcus megaplasmid (DR177. Conclusion After the radiation from their common ancestor, the Thermus and Deinococcus lineages have taken divergent paths toward their distinct lifestyles. In addition to extensive gene loss, Thermus seems to have acquired numerous genes from thermophiles, which likely was the decisive contribution to its thermophilic adaptation. By contrast, Deinococcus lost few genes but seems to have acquired many bacterial genes that apparently enhanced its ability to survive different kinds of environmental stresses. Notwithstanding the accumulation of

  3. Adaptation of the Neural Network Recognition System of the Helicopter on Its Acoustic Radiation to the Flight Speed

    Directory of Open Access Journals (Sweden)

    V. K. Hohlov

    2015-01-01

    Full Text Available The article concerns the adaptation of a neural tract that recognizes a helicopter from the aerodynamic and ground objects by its acoustic radiation to the helicopter flight speed. It uses non-centered informative signs-indications of estimating signal spectra, which correspond to the local extremes (maximums and minimums of the power spectrum of input signal and have the greatest information when differentiating the helicopter signals from those of tracked vehicles. The article gives justification to the principle of the neural network (NN adaptation and adaptation block structure, which solves problems of blade passage frequency estimation when capturing the object and track it when tracking a target, as well as forming a signal to control the resonant filter parameters of the selection block of informative signs. To create the discriminatory characteristics of the discriminator are used autoregressive statistical characteristics of the quadrature components of signal, obtained through the discrete Hilbert Converter (DGC that perforMathematical modeling of the tracking meter using the helicopter signals obtained in real conditions is performed. The article gives estimates of the tracking parameter when using a tracking meter with DGC by sequential records of realized acoustic noise of the helicopter. It also shows a block-diagram of the adaptive NN. The scientific novelty of the work is that providing the invariance of used informative sign, the counts of local extremes of power spectral density (PSD to changes in the helicopter flight speed is reached due to adding the NN structure and adaptation block, which is implemented as a meter to track the apparent passage frequency of the helicopter rotor blades using its relationship with a function of the autoregressive acoustic signal of the helicopter.Specialized literature proposes solutions based on the use of training classifiers with different parametric methods of spectral representations

  4. Characterization of the adaptive response to ionizing radiation induced by low doses of X-rays to Vibrio cholerae cells

    International Nuclear Information System (INIS)

    Basak, Jayasri

    1996-01-01

    Pretreatment with sublethal doses of X-rays induced an adaptive response in Vibrio cholerae cells as indicated by their greater resistance to the subsequent challenging doses of X-irradiation. The adaptive response was maximum following a pre-exposure dose of 1.7 Gy X-rays and an optimum incubation period of 40 min at 37C. Pre-exposure to a sublethal dose of 1.7 Gy X-rays made the Vibrio cholerae cells 3.38-fold more resistant to the subsequent challenge by X-rays. Pretreatment with a sublethal dose of hydrogen peroxide offered a similar degree of protection to the bacterial cells against subsequent treatment with challenging doses of X-ray radiation. However, exposure of Vibrio cholerae cells to mild heat (42C for 10 min) before X-ray irradiation decreased their survival following X-irradiation

  5. Prostate tumor alignment and continuous, real-time adaptive radiation therapy using electromagnetic fiducials: clinical and cost-utility analyses.

    Science.gov (United States)

    Quigley, Martin M; Mate, Timothy P; Sylvester, John E

    2009-01-01

    and monitoring system to have alignment errors exceeding 5 mm. Almost all patients undergoing external beam radiation of the prostate have been shown to have target organ movement exceeding 3 mm during radiation therapy delivery. The ability of the electromagnetic technology to monitor tumor target location during the same time as radiation therapy is being delivered allows clinicians to provide real time adaptive radiation therapy for prostate cancer. This permits clinicians to intervene when the prostate moves outside the radiation isocenter, which should decrease adverse events and improve patient outcomes. Additionally, a cost-utility analysis has demonstrated that the electromagnetic patient positioning and monitoring system offers patient outcome benefits at a cost that falls well within the payer's customary willingness to pay (WTP) threshold of $50,000 per QALY.

  6. Transcontinental dispersal, ecological opportunity and origins of an adaptive radiation in the Neotropical catfish genus Hypostomus (Siluriformes: Loricariidae).

    Science.gov (United States)

    Silva, Gabriel S C; Roxo, Fábio F; Lujan, Nathan K; Tagliacollo, Victor A; Zawadzki, Claudio H; Oliveira, Claudio

    2016-04-01

    Ecological opportunity is often proposed as a driver of accelerated diversification, but evidence has been largely derived from either contemporary island radiations or the fossil record. Here, we investigate the potential influence of ecological opportunity on a transcontinental radiation of South American freshwater fishes. We generate a species-dense, time-calibrated molecular phylogeny for the suckermouth armored catfish subfamily Hypostominae, with a focus on the species-rich and geographically widespread genus Hypostomus. We use the resulting chronogram to estimate ancestral geographical ranges, infer historical rates of cladogenesis and diversification in habitat and body size and shape, and test the hypothesis that invasions of previously unoccupied river drainages accelerated evolution and contributed to adaptive radiation. Both the subfamily Hypostominae and the included genus Hypostomus originated in the Amazon/Orinoco ecoregion. Hypostomus subsequently dispersed throughout tropical South America east of the Andes Mountains. Consequent to invasion of the peripheral, low-diversity Paraná River basin in southeastern Brazil approximately 12.5 Mya, Paraná lineages of Hypostomus, experienced increased rates of cladogenesis and ecological and morphological diversification. Contemporary lineages of Paraná Hypostomus are less species rich but more phenotypically diverse than their congeners elsewhere. Accelerated speciation and morphological diversification rates within Paraná basin Hypostomus are consistent with adaptive radiation. The geographical remoteness of the Paraná River basin, its recent history of marine incursion, and its continuing exclusion of many species that are widespread in other tropical South American rivers suggest that ecological opportunity played an important role in facilitating the observed accelerations in diversification. © 2016 John Wiley & Sons Ltd.

  7. Adaptations to the perimeter environmental radiation monitoring network at the ININ (conceptual design of case)

    International Nuclear Information System (INIS)

    Gonzalez P, M. A.

    2016-01-01

    At present, equipment for the detection of gamma radiation existing in the environment is being developed to protect the population in the Mexico country. The Instituto Nacional de Investigaciones Nucleares (ININ) implemented the gamma radiation monitoring probe (GRMP), which is an instrument used to measure the ionizing radiation in the environment and this in turn communicates with the National Network for Radiological Environmental Monitoring, which detects in real time the gamma radiation. The probes are located in strategic points in the different States of the Mexican Republic and due to their exposure to different types of climate, cause different damages to the case of the GRMP. Due to this situation is that this work is focused on performing different tests to maintain the case in order to validate the problems encountered and investigate new improvements for optimal operation. (Author)

  8. The ecology of an adaptive radiation of three?spined stickleback from North Uist, Scotland

    OpenAIRE

    Magalhaes, Isabel S.; D'Agostino, Daniele; Hohenlohe, Paul A.; MacColl, Andrew D. C.

    2016-01-01

    Abstract There has been a large focus on the genetics of traits involved in adaptation, but knowledge of the environmental variables leading to adaptive changes is surprisingly poor. Combined use of environmental data with morphological and genomic data should allow us to understand the extent to which patterns of phenotypic and genetic diversity within a species can be explained by the structure of the environment. Here, we analyse the variation of populations of three?spined stickleback fro...

  9. Radiation dose response of normal lung assessed by Cone Beam CT - A potential tool for biologically adaptive radiation therapy

    International Nuclear Information System (INIS)

    Bertelsen, Anders; Schytte, Tine; Bentzen, Soren M.; Hansen, Olfred; Nielsen, Morten; Brink, Carsten

    2011-01-01

    Background: Density changes of healthy lung tissue during radiotherapy as observed by Cone Beam CT (CBCT) might be an early indicator of patient specific lung toxicity. This study investigates the time course of CBCT density changes and tests for a possible correlation with locally delivered dose. Methods: A total of 665 CBCTs in 65 lung cancer patients treated with IMRT/VMAT to 60 or 66 Gy in 2 Gy fractions were analyzed. For each patient, CBCT lung density changes during the treatment course were related to the locally delivered dose. Results: A dose response is observed for the patient population at the end of the treatment course. However, the observed dose response is highly variable among patients. Density changes at 10th and 20th fraction are clearly correlated to those observed at the end of the treatment course. Conclusions: CBCT density changes in healthy lung tissue during radiotherapy correlate with the locally delivered dose and can be detected relatively early during the treatment. If these density changes are correlated to subsequent clinical toxicity this assay could form the basis for biological adaptive radiotherapy.

  10. Effects of adaptive statistical iterative reconstruction on radiation dose reduction and diagnostic accuracy of pediatric abdominal CT

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Sohi; Kim, Myung-Joon; Lee, Mi-Jung [Yonsei University College of Medicine, Department of Radiology and Research Institute of Radiological Science, Severance Children' s Hospital, Seoul (Korea, Republic of); Yoon, Choon-Sik [Yonsei University College of Medicine, Department of Radiology, Gangnam Severance Hospital, Seoul (Korea, Republic of); Kim, Dong Wook; Hong, Jung Hwa [Yonsei University College of Medicine, Biostatistics Collaboration Unit, Seoul (Korea, Republic of)

    2014-12-15

    Since children are more radio-sensitive than adults, there is a need to minimize radiation exposure during CT exams. To evaluate the effects of adaptive statistical iterative reconstruction (ASIR) on radiation dose reduction, image quality and diagnostic accuracy in pediatric abdominal CT. We retrospectively reviewed the abdominal CT examinations of 41 children (24 boys and 17 girls; mean age: 10 years) with a low-dose radiation protocol and reconstructed with ASIR (the ASIR group). We also reviewed routine-dose abdominal CT examinations of 41 age- and sex-matched controls reconstructed with filtered-back projection (control group). Image quality was assessed objectively as noise measured in the liver, spleen and aorta, as well as subjectively by three pediatric radiologists for diagnostic acceptability using a four-point scale. Radiation dose and objective image qualities of each group were compared with the paired t-test. Diagnostic accuracy was evaluated by reviewing follow-up imaging studies and medical records in 2012 and 2013. There was 46.3% dose reduction of size-specific dose estimates in ASIR group (from 13.4 to 7.2 mGy) compared with the control group. Objective noise was higher in the liver, spleen and aorta of the ASIR group (P < 0.001). However, the subjective image quality was average or superior in 84-100% of studies. Only one image was subjectively rated as unacceptable by one reviewer. There was only one case with interpretational error in the control group and none in the ASIR group. Use of the ASIR technique resulted in greater than a 45% reduction in radiation dose without impairing subjective image quality or diagnostic accuracy in pediatric abdominal CT, despite increased objective image noise. (orig.)

  11. New scanning technique using Adaptive Statistical lterative Reconstruction (ASIR) significantly reduced the radiation dose of cardiac CT

    International Nuclear Information System (INIS)

    Tumur, Odgerel; Soon, Kean; Brown, Fraser; Mykytowycz, Marcus

    2013-01-01

    The aims of our study were to evaluate the effect of application of Adaptive Statistical Iterative Reconstruction (ASIR) algorithm on the radiation dose of coronary computed tomography angiography (CCTA) and its effects on image quality of CCTA and to evaluate the effects of various patient and CT scanning factors on the radiation dose of CCTA. This was a retrospective study that included 347 consecutive patients who underwent CCTA at a tertiary university teaching hospital between 1 July 2009 and 20 September 2011. Analysis was performed comparing patient demographics, scan characteristics, radiation dose and image quality in two groups of patients in whom conventional Filtered Back Projection (FBP) or ASIR was used for image reconstruction. There were 238 patients in the FBP group and 109 patients in the ASIR group. There was no difference between the groups in the use of prospective gating, scan length or tube voltage. In ASIR group, significantly lower tube current was used compared with FBP group, 550mA (450–600) vs. 650mA (500–711.25) (median (interquartile range)), respectively, P<0.001. There was 27% effective radiation dose reduction in the ASIR group compared with FBP group, 4.29mSv (2.84–6.02) vs. 5.84mSv (3.88–8.39) (median (interquartile range)), respectively, P<0.001. Although ASIR was associated with increased image noise compared with FBP (39.93±10.22 vs. 37.63±18.79 (mean ±standard deviation), respectively, P<001), it did not affect the signal intensity, signal-to-noise ratio, contrast-to-noise ratio or the diagnostic quality of CCTA. Application of ASIR reduces the radiation dose of CCTA without affecting the image quality.

  12. Adaptation of the delta-m and δ-fit truncation methods to vector radiative transfer: Effect of truncation on radiative transfer accuracy

    International Nuclear Information System (INIS)

    Sanghavi, Suniti; Stephens, Graeme

    2015-01-01

    In the presence of aerosol and/or clouds, the use of appropriate truncation methods becomes indispensable for accurate but cost-efficient radiative transfer computations. Truncation methods allow the reduction of the large number (usually several hundreds) of Fourier components associated with particulate scattering functions to a more manageable number, thereby making it possible to carry out radiative transfer computations with a modest number of streams. While several truncation methods have been discussed for scalar radiative transfer, few rigorous studies have been made of truncation methods for the vector case. Here, we formally derive the vector form of Wiscombe's delta-m truncation method. Two main sources of error associated with delta-m truncation are identified as the delta-separation error (DSE) and the phase-truncation error (PTE). The view angles most affected by truncation error occur in the vicinity of the direction of exact backscatter. This view geometry occurs commonly in satellite based remote sensing applications, and is hence of considerable importance. In order to deal with these errors, we adapt the δ-fit approach of Hu et al. (2000) [17] to vector radiative transfer. The resulting δBGE-fit is compared with the vectorized delta-m method. For truncation at l=25 of an original phase matrix consisting of over 300 Fourier components, the use of the δBGE-fit minimizes the error due to truncation at these view angles, while practically eliminating error at other angles. We also show how truncation errors have a distorting effect on hyperspectral absorption line shapes. The choice of the δBGE-fit method over delta-m truncation minimizes errors in absorption line depths, thus affording greater accuracy for sensitive retrievals such as those of XCO 2 from OCO-2 or GOSAT measurements. - Highlights: • Derives vector form for delta-m truncation method. • Adapts δ-fit truncation approach to vector RTE as δBGE-fit. • Compares truncation

  13. Adaptation strategies of endolithic chlorophototrophs to survive the hyperarid and extreme solar radiation environment of the Atacama Desert.

    Science.gov (United States)

    Wierzchos, Jacek; DiRuggiero, Jocelyne; Vítek, Petr; Artieda, Octavio; Souza-Egipsy, Virginia; Škaloud, Pavel; Tisza, Michel; Davila, Alfonso F; Vílchez, Carlos; Garbayo, Inés; Ascaso, Carmen

    2015-01-01

    The Atacama Desert, northern Chile, is one of the driest deserts on Earth and, as such, a natural laboratory to explore the limits of life and the strategies evolved by microorganisms to adapt to extreme environments. Here we report the exceptional adaptation strategies of chlorophototrophic and eukaryotic algae, and chlorophototrophic and prokaryotic cyanobacteria to the hyperarid and extremely high solar radiation conditions occurring in this desert. Our approach combined several microscopy techniques, spectroscopic analytical methods, and molecular analyses. We found that the major adaptation strategy was to avoid the extreme environmental conditions by colonizing cryptoendolithic, as well as, hypoendolithic habitats within gypsum deposits. The cryptoendolithic colonization occurred a few millimeters beneath the gypsum surface and showed a succession of organized horizons of algae and cyanobacteria, which has never been reported for endolithic microbial communities. The presence of cyanobacteria beneath the algal layer, in close contact with sepiolite inclusions, and their hypoendolithic colonization suggest that occasional liquid water might persist within these sub-microhabitats. We also identified the presence of abundant carotenoids in the upper cryptoendolithic algal habitat and scytonemin in the cyanobacteria hypoendolithic habitat. This study illustrates that successful lithobiontic microbial colonization at the limit for microbial life is the result of a combination of adaptive strategies to avoid excess solar irradiance and extreme evapotranspiration rates, taking advantage of the complex structural and mineralogical characteristics of gypsum deposits-conceptually called "rock's habitable architecture." Additionally, self-protection by synthesis and accumulation of secondary metabolites likely produces a shielding effect that prevents photoinhibition and lethal photooxidative damage to the chlorophototrophs, representing another level of adaptation.

  14. Adaptation strategies of endolithic chlorophototrophs to survive the hyperarid and extreme solar radiation environment of the Atacama Desert

    Directory of Open Access Journals (Sweden)

    Jacek eWierzchos

    2015-09-01

    Full Text Available The Atacama Desert, northern Chile, is one of the driest deserts on Earth and, as such, a natural laboratory to explore the limits of life and the strategies evolved by microorganisms to adapt to extreme environments. Here we report the exceptional adaptation strategies of chlorophototrophic and eukaryotic algae, and chlorophototrophic and prokaryotic cyanobacteria to the hyperarid and extremely high solar radiation conditions occurring in this desert. Our approach combined several microscopy techniques, spectroscopic analytical methods, and molecular analyses. We found that the major adaptation strategy was to avoid the extreme environmental conditions by colonizing cryptoendolithic, as well as, hypoendolithic habitats within gypsum deposits. The cryptoendolithic colonization occurred a few millimeters beneath the gypsum surface and showed a succession of organized horizons of algae and cyanobacteria, which has never been reported for endolithic microbial communities. The presence of cyanobacteria beneath the algal layer, in close contact with sepiolite inclusions, and their hypoendolithic colonization suggest that occasional liquid water might persist within these sub-microhabitats. We also identified the presence of abundant carotenoids in the upper cryptoendolithic algal habitat and scytonemin in the cyanobacteria hypoendolithic habitat. This study illustrates that successful lithobiontic microbial colonization at the limit for microbial life is the result of a combination of adaptive strategies to avoid excess solar irradiance and extreme evapotranspiration rates, taking advantage of the complex structural and mineralogical characteristics of gypsum deposits – conceptually called rock’s habitable architecture. Additionally self-protection by synthesis and accumulation of secondary metabolites likely produces a shielding effect that prevents photoinhibition and lethal photooxidative damage to the chlorophototrophs, representing another

  15. Acute adaptive immune response correlates with late radiation-induced pulmonary fibrosis in mice.

    Science.gov (United States)

    Paun, Alexandra; Kunwar, Amit; Haston, Christina K

    2015-02-20

    The lung response to radiation exposure can involve an immediate or early reaction to the radiation challenge, including cell death and an initial immune reaction, and can be followed by a tissue injury response, of pneumonitis or fibrosis, to this acute reaction. Herein, we aimed to determine whether markers of the initial immune response, measured within days of radiation exposure, are correlated with the lung tissue injury responses occurring weeks later. Inbred strains of mice known to be susceptible (KK/HIJ, C57BL/6J, 129S1/SvImJ) or resistant (C3H/HeJ, A/J, AKR/J) to radiation-induced pulmonary fibrosis and to vary in time to onset of respiratory distress post thoracic irradiation (from 10-23 weeks) were studied. Mice were untreated (controls) or received 18 Gy whole thorax irradiation and were euthanized at 6 h, 1d or 7 d after radiation treatment. Pulmonary CD4+ lymphocytes, bronchoalveolar cell profile & cytokine level, and serum cytokine levels were assayed. Thoracic irradiation and inbred strain background significantly affected the numbers of CD4+ cells in the lungs and the bronchoalveolar lavage cell differential of exposed mice. At the 7 day timepoint greater numbers of pulmonary Th1 and Th17 lymphocytes and reduced lavage interleukin17 and interferonγ levels were significant predictors of late stage fibrosis. Lavage levels of interleukin-10, measured at the 7 day timepoint, were inversely correlated with fibrosis score (R=-0.80, p=0.05), while serum levels of interleukin-17 in control mice significantly correlated with post irradiation survival time (R=0.81, p=0.04). Lavage macrophage, lymphocyte or neutrophil counts were not significantly correlated with either of fibrosis score or time to respiratory distress in the six mouse strains. Specific cytokine and lymphocyte levels, but not strain dependent lavage cell profiles, were predictive of later radiation-induced lung injury in this panel of inbred strains.

  16. Reduction of radiation exposure and improvement of image quality with BMI-adapted prospective cardiac computed tomography and iterative reconstruction

    International Nuclear Information System (INIS)

    Hosch, Waldemar; Stiller, Wolfram; Mueller, Dirk; Gitsioudis, Gitsios; Welzel, Johanna; Dadrich, Monika; Buss, Sebastian J.; Giannitsis, Evangelos; Kauczor, Hans U.; Katus, Hugo A.; Korosoglou, Grigorios

    2012-01-01

    Purpose: To assess the impact of body mass index (BMI)-adapted protocols and iterative reconstruction algorithms (iDose) on patient radiation exposure and image quality in patients undergoing prospective ECG-triggered 256-slice coronary computed tomography angiography (CCTA). Methods: Image quality and radiation exposure were systematically analyzed in 100 patients. 60 Patients underwent prospective ECG-triggered CCTA using a non-tailored protocol and served as a ‘control’ group (Group 1: 120 kV, 200 mA s). 40 Consecutive patients with suspected coronary artery disease (CAD) underwent prospective CCTA, using BMI-adapted tube voltage and standard (Group 2: 100/120 kV, 100–200 mA s) versus reduced tube current (Group 3: 100/120 kV, 75–150 mA s). Iterative reconstructions were provided with different iDose levels and were compared to filtered back projection (FBP) reconstructions. Image quality was assessed in consensus of 2 experienced observers and using a 5-grade scale (1 = best to 5 = worse), and signal- and contrast-to-noise ratios (SNR and CNR) were quantified. Results: CCTA was performed without adverse events in all patients (n = 100, heart rate of 47–87 bpm and BMI of 19–38 kg/m 2 ). Patients examined using the non-tailored protocol in Group 1 had the highest radiation exposure (3.2 ± 0.4 mSv), followed by Group 2 (1.7 ± 0.7 mSv) and Group 3 (1.2 ± 0.6 mSv) (radiation savings of 47% and 63%, respectively, p < 0.001). Iterative reconstructions provided increased SNR and CNR, particularly when higher iDose level 5 was applied with Multi-Frequency reconstruction (iDose5 MFR) (14.1 ± 4.6 versus 21.2 ± 7.3 for SNR and 12.0 ± 4.2 versus 18.1 ± 6.6 for CNR, for FBP versus iDose5 MFR, respectively, p < 0.001). The combination of BMI adaptation with iterative reconstruction reduced radiation exposure and simultaneously improved image quality (subjective image quality of 1.4 ± 0.4 versus 1.9 ± 0.5 for Group 2 reconstructed using iDose5 MFR versus

  17. Adaptive response in human blood lymphocytes exposed to non-ionizing radiofrequency fields: resistance to ionizing radiation-induced damage.

    Science.gov (United States)

    Sannino, Anna; Zeni, Olga; Romeo, Stefania; Massa, Rita; Gialanella, Giancarlo; Grossi, Gianfranco; Manti, Lorenzo; Vijayalaxmi; Scarfì, Maria Rosaria

    2014-03-01

    The aim of this preliminary investigation was to assess whether human peripheral blood lymphocytes which have been pre-exposed to non-ionizing radiofrequency fields exhibit an adaptive response (AR) by resisting the induction of genetic damage from subsequent exposure to ionizing radiation. Peripheral blood lymphocytes from four healthy donors were stimulated with phytohemagglutinin for 24 h and then exposed for 20 h to 1950 MHz radiofrequency fields (RF, adaptive dose, AD) at an average specific absorption rate of 0.3 W/kg. At 48 h, the cells were subjected to a challenge dose (CD) of 1.0 or 1.5 Gy X-irradiation (XR, challenge dose, CD). After a 72 h total culture period, cells were collected to examine the incidence of micronuclei (MN). There was a significant decrease in the number of MN in lymphocytes exposed to RF + XR (AD + CD) as compared with those subjected to XR alone (CD). These observations thus suggested a RF-induced AR and induction of resistance to subsequent damage from XR. There was variability between the donors in RF-induced AR. The data reported in our earlier investigations also indicated a similar induction of AR in human blood lymphocytes that had been pre-exposed to RF (AD) and subsequently treated with a chemical mutagen, mitomycin C (CD). Since XR and mitomycin-C induce different kinds of lesions in cellular DNA, further studies are required to understand the mechanism(s) involved in the RF-induced adaptive response.

  18. Magnetic Resonance Imaging-Guided Adaptive Radiation Therapy: A "Game Changer" for Prostate Treatment?

    NARCIS (Netherlands)

    Pathmanathan, Angela U.; van As, Nicholas J.; Kerkmeijer, Linda G. W.; Christodouleas, John; Lawton, Colleen A. F.; Vesprini, Danny; van der Heide, Uulke A.; Frank, Steven J.; Nill, Simeon; Oelfke, Uwe; van Herk, Marcel; Li, X. Allen; Mittauer, Kathryn; Ritter, Mark; Choudhury, Ananya; Tree, Alison C.

    2018-01-01

    Radiation therapy to the prostate involves increasingly sophisticated delivery techniques and changing fractionation schedules. With a low estimated α/β ratio, a larger dose per fraction would be beneficial, with moderate fractionation schedules rapidly becoming a standard of care. The integration

  19. The Dynamics of Incomplete Lineage Sorting across the Ancient Adaptive Radiation of Neoavian Birds

    OpenAIRE

    Roberts, Roland G.

    2015-01-01

    Rapid sequential speciation events can outpace the fixation of genetic variants, resulting in a family tree that lacks clear branching patterns. A new study of bird genomes reveals such an explosive super-radiation that may coincide with the mass extinction at the end of the Cretaceous period.

  20. Radiative cooling in numerical astrophysics: The need for adaptive mesh refinement

    NARCIS (Netherlands)

    van Marle, A. J.; Keppens, R.

    2011-01-01

    Energy loss through optically thin radiative cooling plays an important part in the evolution of astrophysical gas dynamics and should therefore be considered a necessary element in any numerical simulation. Although the addition of this physical process to the equations of hydrodynamics is

  1. Adaptive response and split-dose effect of radiation on the survival ...

    Indian Academy of Sciences (India)

    These results clearly showed the occurrence of adaptive response in terms of survival of animals. The conditioning dose given in small fractions seemed to be more effective. The findings have been discussed from a mechanistic point of view. The possible biological implications, potential medical benefits, uncertainties and ...

  2. Adaptation of the Black Yeast Wangiella dermatitidis to Ionizing Radiation: Molecular and Cellular Mechanisms

    Science.gov (United States)

    2012-11-01

    days (Figure 1B), which agreed with the result reported by Dadachova et al [6]. However, the increased cell number was also observed when the albino ...to the increased number of in un-budded cells in the culture. In addition, it appeared that deletion of the WdPKS1 gene not only resulted in the albino ...expressed genes specific to either the melanized or albino strain. Therefore, before investigating the cellular response to radiation, we first determined

  3. The construction of standardised equipment expressly adapted to the different methods of radiation control

    International Nuclear Information System (INIS)

    Savouyaud, J.; Menoux, A.

    1960-01-01

    The authors show what general characteristics must have equipment designed for radiation control. This equipment must make possible the measurement of doses corresponding to 1/10 of the maximum permissible limit. It should be designed for a specific purpose, and finally it should be independent as far as possible. The authors review the different types of control which it is necessary to effect. (author) [fr

  4. Feasibility of breathing-adapted PET/CT imaging for radiation therapy of Hodgkin lymphoma

    DEFF Research Database (Denmark)

    Aznar, M C; Andersen, Flemming; Berthelsen, A K

    2011-01-01

    Aim: Respiration can induce artifacts in positron emission tomography (PET)/computed tomography (CT) images leading to uncertainties in tumour volume, location and uptake quantification. Respiratory gating for PET images is now established but is not directly translatable to a radiotherapy setup....... in PET/CT images. These results suggest that advanced therapies (such as SUV-based dose painting) will likely require breathing-adapted PET images and that the relevant SUV thresholds are yet to be investigated....

  5. Feasibility of breathing-adapted PET/CT imaging for radiation therapy of Hodgkin lymphoma

    DEFF Research Database (Denmark)

    Aznar, M C; Andersen, Flemming; Berthelsen, A K

    2011-01-01

    Aim: Respiration can induce artifacts in positron emission tomography (PET)/computed tomography (CT) images leading to uncertainties in tumour volume, location and uptake quantification. Respiratory gating for PET images is now established but is not directly translatable to a radiotherapy setup....... uptake in PET/CT images. These results suggest that advanced therapies (such as SUV-based dose painting) will likely require breathing-adapted PET images and that the relevant SUV thresholds are yet to be investigated....

  6. The absence of radiation-induced adaptive response in lymphocytes of patients with Down's syndrome

    International Nuclear Information System (INIS)

    Khandogina, E.K.; Mutovin, G.R.; Zvereva, S.V.; Zverev, D.O.; Neudakhin, E.V.; Arkhipov, B.A.; Akif'ev, A.P.; AN SSSR, Moscow

    1991-01-01

    The adaptive syndrome and response (AR) in lymphocytes from 6 patients with Down syndrome (DS) were investigated. No AR was found to occur in all cases in DS cells pre-exposed to 3 rad of X-rays in S phase of cell cycle and then irradiated with 150 rad of gamma rays in G2 whereas the chromosome aberrations yield in cells from control donors was decreased twice under such conditions of the experiment

  7. Adaptive responses of living cells towards low-doses of radiation. Induction of endogenous antioxidant system and its applicable possibility for treatment of diseases

    International Nuclear Information System (INIS)

    Kojima, Shuji; Yamaoka, Kiyonori

    1999-01-01

    Bacteria and mammalian cells show an adaptive response to oxidative stress. Pre-treatment with small amounts of oxidant induces resistance to the subsequent, otherwise lethal, doses of oxidant. Previous studies have shown that this adaptive response involves the induction of superoxide dismutase (SOD), glutathione peroxidase (GPX), metallothionein, heat shock proteins, and other factors. The toxicity of ionizing radiation, particularly at low doses, to living cells, is thought to be due to reactive oxygen species (ROS) formation. Thus, adaptive responses to low doses of ionizing radiation and to oxidants are likely to be similar. In this paper, the induction of endogenous glutathione (GSH) together with antioxidant enzymes induced by low-dose radiation was reviewed. Furthermore, the applicable possibility of this efficacy for the prevention of and/or therapy of various reactive oxygen species (ROS)-related diseases including Parkinson's diseases, aging, and diabetes, was discussed. (author)

  8. The RBE of tritium-beta exposure for the induction of the adaptive response and apoptosis; cellular defense mechanisms against the biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    Boreham, D.R.; Bahen, M.E.; Dolling, J-A.

    1997-01-01

    Adaption to radiation is one of a few biological responses that has been demonstrated to occur in mammalian cells exposed to doses of ionizing radiation in the occupational exposure range. The adaptive response has been well characterized in the yeast Saccharomyces cerevisiae, although the doses required to induce the response are higher than in mammalian cells. When yeast cells are primed with sublethal doses of gamma-radiation, they subsequently undergo an adaptive response and develop resistance to radiation, heat the chemical mutagens in a time and dose dependent manner. We have used this model system to assess the relative ability of tritium-beta radiation to induce the adaptive response the examined tritium-induced radiation resistance, thermal tolerance and suppression of mutation. The results show that sublethal priming doses of tritium caused yeast cells to develop resistance to radiation, heat, and a chemical mutagen MNNG. The magnitude and kinetics of the response, per unit dose, were the same for tritium and gamma-radiation. Therefore, the relative biological effectiveness (RBE) of tritium induction of the adaptive response was about 1.0. Apoptosis is a genetically programmed cell death or cell suicide. Cells damaged by radiation can be selectively removed from the population by apoptosis and therefore eliminated as a potential cancer risk to the organism. Since we have previously shown that apoptosis is a sensitive indicator of radiation damage in human lymphocytes exposed to low doses, we have used this endpoint to investigate the potency of tritium-beta radiation. Initially, tritium was compared to X-rays for relative effectiveness at inducing apoptosis. The results showed the lymphocytes irradiated in vitro with X-rays or tritium had similar levels of apoptosis per unit dose. Therefore the relative biology effectiveness of tritium for induction of apoptosis in human lymphocytes was also about 1. In the work presented here, we have demonstrated that

  9. Adaptive response after combined treatment of human lymphocytes with deltamethrin and radiation

    Energy Technology Data Exchange (ETDEWEB)

    Cebulska-Wasilewska, A.; Wierzewska, A.; Kaspar, E.; Krzykwa, B. [Institute of Nuclear Physics, Cracow (Poland)

    1996-12-31

    This paper presents results of combined treatments of human lymphocytes by deltamethrin and X-ray radiation. Cells were stimulated and incubated for twenty-four hours to ensure their growth. To the cultures selected for chemical pretreatment deltamethrin was added. After four hours the medium in all cultures had been replaced and cells were incubated for another 20 hours. Then, selected samples were irradiated with acute (1 Gy) and split (twice 0.5 Gy) doses of radiation. Doses split into two parts had two hour long intervals between irradiations. Results of radiation performed alone showed a very low frequencies of chromosome type aberrations (dicentrics and rings) and elevated frequency of fragments, tri radials and quadriradials instead. The results also showed a higher level of induced chromosome damage after a split dose than after the acute one. The frequencies of aberrations observed after irradiation of chemically pretreated cells were lower than values expected on the base of additive effect from individual treatments. (author). 16 refs, 2 figs, 2 tabs.

  10. Convergent evolution of SWS2 opsin facilitates adaptive radiation of threespine stickleback into different light environments.

    Directory of Open Access Journals (Sweden)

    David A Marques

    2017-04-01

    Full Text Available Repeated adaptation to a new environment often leads to convergent phenotypic changes whose underlying genetic mechanisms are rarely known. Here, we study adaptation of color vision in threespine stickleback during the repeated postglacial colonization of clearwater and blackwater lakes in the Haida Gwaii archipelago. We use whole genomes from 16 clearwater and 12 blackwater populations, and a selection experiment, in which stickleback were transplanted from a blackwater lake into an uninhabited clearwater pond and resampled after 19 y to test for selection on cone opsin genes. Patterns of haplotype homozygosity, genetic diversity, site frequency spectra, and allele-frequency change support a selective sweep centered on the adjacent blue- and red-light sensitive opsins SWS2 and LWS. The haplotype under selection carries seven amino acid changes in SWS2, including two changes known to cause a red-shift in light absorption, and is favored in blackwater lakes but disfavored in the clearwater habitat of the transplant population. Remarkably, the same red-shifting amino acid changes occurred after the duplication of SWS2 198 million years ago, in the ancestor of most spiny-rayed fish. Two distantly related fish species, bluefin killifish and black bream, express these old paralogs divergently in black- and clearwater habitats, while sticklebacks lost one paralog. Our study thus shows that convergent adaptation to the same environment can involve the same genetic changes on very different evolutionary time scales by reevolving lost mutations and reusing them repeatedly from standing genetic variation.

  11. Adaptive melanin response of the soil fungus Aspergillus niger to UV radiation stress at "Evolution Canyon", Mount Carmel, Israel.

    Directory of Open Access Journals (Sweden)

    Natarajan Singaravelan

    Full Text Available BACKGROUND: Adaptation is an evolutionary process in which traits in a population are tailored by natural selection to better meet the challenges presented by the local environment. The major discussion relating to natural selection concerns the portraying of the cause and effect relationship between a presumably adaptive trait and selection agents generating it. Therefore, it is necessary to identify trait(s that evolve in direct response to selection, enhancing the organism's fitness. "Evolution Canyon" (EC in Israel mirrors a microcosmic evolutionary system across life and is ideal to study natural selection and local adaptation under sharply, microclimatically divergent environments. The south-facing, tropical, sunny and xeric "African" slope (AS receives 200%-800% higher solar radiation than the north-facing, temperate, shady and mesic "European" slope (ES, 200 meters apart. Thus, solar ultraviolet radiation (UVR is a major selection agent in EC influencing the organism-environment interaction. Melanin is a trait postulated to have evolved for UV-screening in microorganisms. Here we investigate the cause and effect relationship between differential UVR on the opposing slopes of EC and the conidial melanin concentration of the filamentous soil fungus Aspergillus niger. We test the working hypothesis that the AS strains exhibit higher melanin content than strains from the ES resulting in higher UV resistance. METHODOLOGY/PRINCIPAL FINDINGS: We measured conidial melanin concentration of 80 strains from the EC using a spectrophotometer. The results indicated that mean conidial melanin concentration of AS strains were threefold higher than ES strains and the former resisted UVA irradiation better than the latter. Comparisons of melanin in the conidia of A. niger strains from sunny and shady microniches on the predominantly sunny AS and predominantly shady ES indicated that shady conditions on the AS have no influence on the selection on melanin

  12. Detecting gravitational radiation from neutron stars using a six-parameter adaptive MCMC method

    CERN Document Server

    Umstätter, R; Dupuis, R J; Veitch, J; Woan, G; Christensen, N; Umst\\"atter, Richard; Meyer, Renate; Veitch, John; Woan, Graham; Christensen, Nelson

    2004-01-01

    We present a Markov chain Monte Carlo technique for detecting gravitational radiation from a neutron star in laser interferometer data. The algorithm can estimate up to six unknown parameters of the target, including the rotation frequency and frequency derivative, using reparametrization, delayed rejection and simulated annealing. We highlight how a simple extension of the method, distributed over multiple computer processors, will allow for a search over a narrow frequency band. The ultimate goal of this research is to search for sources at a known locations, but uncertain spin parameters, such as may be found in SN1987A.

  13. Head and Neck Margin Reduction With Adaptive Radiation Therapy: Robustness of Treatment Plans Against Anatomy Changes

    Energy Technology Data Exchange (ETDEWEB)

    Kranen, Simon van; Hamming-Vrieze, Olga; Wolf, Annelisa; Damen, Eugène [Department of Radiation Oncology, Netherlands Cancer Institute, Amsterdam (Netherlands); Herk, Marcel van [Christie Hospital and University of Manchester, Manchester (United Kingdom); Sonke, Jan-Jakob, E-mail: j.sonke@nki.nl [Department of Radiation Oncology, Netherlands Cancer Institute, Amsterdam (Netherlands)

    2016-11-01

    Purpose: We set out to investigate loss of target coverage from anatomy changes in head and neck cancer patients as a function of applied safety margins and to verify a cone beam computed tomography (CBCT)–based adaptive strategy with an average patient anatomy to overcome possible target underdosage. Methods and Materials: For 19 oropharyngeal cancer patients, volumetric modulated arc therapy treatment plans (2 arcs; simultaneous integrated boost, 70 and 54.25 Gy; 35 fractions) were automatically optimized with uniform clinical target volume (CTV)–to–planning target volume margins of 5, 3, and 0 mm. We applied b-spline CBCT–to–computed tomography (CT) deformable registration to allow recalculation of the dose on modified CT scans (planning CT deformed to daily CBCT following online positioning) and dose accumulation in the planning CT scan. Patients with deviations in primary or elective CTV coverage >2 Gy were identified as candidates for adaptive replanning. For these patients, a single adaptive intervention was simulated with an average anatomy from the first 10 fractions. Results: Margin reduction from 5 mm to 3 mm to 0 mm generally led to an organ-at-risk (OAR) mean dose (D{sub mean}) sparing of approximately 1 Gy/mm. CTV shrinkage was mainly seen in the elective volumes (up to 10%), likely related to weight loss. Despite online repositioning, substantial systematic errors were present (>3 mm) in lymph node CTV, the parotid glands, and the larynx. Nevertheless, the average increase in OAR dose was small: maximum of 1.2 Gy (parotid glands, D{sub mean}) for all applied margins. Loss of CTV coverage >2 Gy was found in 1, 3, and 7 of 73 CTVs, respectively. Adaptive intervention in 0-mm plans substantially improved coverage: in 5 of 7 CTVs (in 6 patients) to <2 Gy of initially planned. Conclusions: Volumetric modulated arc therapy head and neck cancer treatment plans with 5-mm margins are robust for anatomy changes and show a modest

  14. Head and Neck Margin Reduction With Adaptive Radiation Therapy: Robustness of Treatment Plans Against Anatomy Changes

    International Nuclear Information System (INIS)

    Kranen, Simon van; Hamming-Vrieze, Olga; Wolf, Annelisa; Damen, Eugène; Herk, Marcel van; Sonke, Jan-Jakob

    2016-01-01

    Purpose: We set out to investigate loss of target coverage from anatomy changes in head and neck cancer patients as a function of applied safety margins and to verify a cone beam computed tomography (CBCT)–based adaptive strategy with an average patient anatomy to overcome possible target underdosage. Methods and Materials: For 19 oropharyngeal cancer patients, volumetric modulated arc therapy treatment plans (2 arcs; simultaneous integrated boost, 70 and 54.25 Gy; 35 fractions) were automatically optimized with uniform clinical target volume (CTV)–to–planning target volume margins of 5, 3, and 0 mm. We applied b-spline CBCT–to–computed tomography (CT) deformable registration to allow recalculation of the dose on modified CT scans (planning CT deformed to daily CBCT following online positioning) and dose accumulation in the planning CT scan. Patients with deviations in primary or elective CTV coverage >2 Gy were identified as candidates for adaptive replanning. For these patients, a single adaptive intervention was simulated with an average anatomy from the first 10 fractions. Results: Margin reduction from 5 mm to 3 mm to 0 mm generally led to an organ-at-risk (OAR) mean dose (D mean ) sparing of approximately 1 Gy/mm. CTV shrinkage was mainly seen in the elective volumes (up to 10%), likely related to weight loss. Despite online repositioning, substantial systematic errors were present (>3 mm) in lymph node CTV, the parotid glands, and the larynx. Nevertheless, the average increase in OAR dose was small: maximum of 1.2 Gy (parotid glands, D mean ) for all applied margins. Loss of CTV coverage >2 Gy was found in 1, 3, and 7 of 73 CTVs, respectively. Adaptive intervention in 0-mm plans substantially improved coverage: in 5 of 7 CTVs (in 6 patients) to <2 Gy of initially planned. Conclusions: Volumetric modulated arc therapy head and neck cancer treatment plans with 5-mm margins are robust for anatomy changes and show a modest increase in OAR

  15. Herbivory Promotes Dental Disparification and Macroevolutionary Dynamics in Grunters (Teleostei: Terapontidae), a Freshwater Adaptive Radiation.

    Science.gov (United States)

    Davis, Aaron M; Unmack, Peter J; Vari, Richard P; Betancur-R, Ricardo

    2016-03-01

    Trophic shifts into new adaptive zones have played major (although often conflicting) roles in reshaping the evolutionary trajectories of many lineages. We analyze data on diet, tooth, and oral morphology and relate these traits to phenotypic disparification and lineage diversification rates across the ecologically diverse Terapontidae, a family of Australasian fishes. In contrast to carnivores and most omnivores, which have retained relatively simple, ancestral caniniform tooth shapes, herbivorous terapontids appear to have evolved a variety of novel tooth shapes at significantly faster rates to meet the demands of plant-based diets. The evolution of herbivory prompted major disparification, significantly expanding the terapontid adaptive phenotypic continuum into an entirely novel functional morphospace. There was minimal support for our hypothesis of faster overall rates of integrated tooth shape, spacing, and jaw biomechanical evolution in herbivorous terapontids in their entirety, compared with other trophic strategies. There was, however, considerable support for accelerated disparification within a diverse freshwater clade containing a range of specialized freshwater herbivores. While the evolutionary transition to herbivorous diets has played a central role in terapontid phenotypic diversification by pushing herbivores toward novel fitness peaks, there was little support for herbivory driving significantly higher lineage diversification compared with background rates across the family.

  16. Low-Dose Radiation-Induced Adaptive Response in Polychromatic Mice Erythrocyte as Measured by Acridine Orange Stained Micronuleus Assay

    International Nuclear Information System (INIS)

    Hee-Sun, K.; Kwang-Hee, Y.; Cha-Soom, K.; Jung-Mi, C.; Gu-Choul, S.; Suk-Young, P.; Kyoung-H, C.; Chong-Soom, K.; Young-Khi, L.; Jae-Ho, W.

    2004-01-01

    The effect of conditioning pretreatment with 0.01Gy of gamma rays on micronucleated polychromatic erythrocyte (MN-PCE) induction by 2Gy of g-rays was determined in peripheral blood of C3H/He mice. The timing of their administration of challenge doses was 6hr. The response was determined by scoring of Acridine orange dye stained MN-PCEs. The results indicate that low dose gamma ray pretreatment does protect against MN-PCE induction by the challenge g-ray dose. Introduction: An adaptive response induced by low doses of ionizing radiation in vivo reported. Some research team reports that a reduction on MN-PCE of mice caused by the pretreatment was observed [1- 4]. However, there was variability in the amount of the response depending on the time and adaptive dose [3]. This is important because the variation of MN-PCE frequency with time could lead to differences in the interpretation. In this study, differences in the biological effects within the priming dose ranges are discussed. Materials and Methods: Specific pathogen free 5-week-old C3H/He mice, purchased from Shizuoka Laboratory Center (Japan), were kept in clean and conventional environment. When 6 weeks old, the animal were whole body irradiated using irradiator of IBL-437 (137Cs, 0.8Gy/min). After various time intervals, the two groups were administrated to adaptation dose and challenge dose of 0.01Gy and 2Gy, respectively. For experiments, sham-irradiated, only adaptive and challenge dose irradiated groups were run concurrently. Smears were stained and scored using Acridine orange dye method [2]. Statistically significant differences in MN-PCE frequency were determined by comparing tie individual values at each group with the respective control values (challenge dose irradiated group) by using the paired ttest. Results and Discussions: Induced MN by the challenge dose (2Gy) after the pretreatment with 0.01Gy is low to the one induced by the challenge dose alone. In the present study, this estimation for the

  17. Characterization of the adaptive response of grapevine (cv. Tempranillo) to UV-B radiation under water deficit conditions.

    Science.gov (United States)

    Martínez-Lüscher, J; Morales, F; Delrot, S; Sánchez-Díaz, M; Gomès, E; Aguirreolea, J; Pascual, I

    2015-03-01

    This work aims to characterize the physiological response of grapevine (Vitis vinifera L.) cv. Tempranillo to UV-B radiation under water deficit conditions. Grapevine fruit-bearing cuttings were exposed to three levels of supplemental biologically effective UV-B radiation (0, 5.98 and 9.66kJm(-2)day(-1)) and two water regimes (well watered and water deficit), in a factorial design, from fruit-set to maturity under glasshouse-controlled conditions. UV-B induced a transient decrease in net photosynthesis (Anet), actual and maximum potential efficiency of photosystem II, particularly on well watered plants. Methanol extractable UV-B absorbing compounds (MEUVAC) concentration and superoxide dismutase activity increased with UV-B. Water deficit effected decrease in Anet and stomatal conductance, and did not change non-photochemical quenching and the de-epoxidation state of xanthophylls, dark respiration and photorespiration being alternative ways to dissipate the excess of energy. Little interactive effects between UV-B and drought were detected on photosynthesis performance, where the impact of UV-B was overshadowed by the effects of water deficit. Grape berry ripening was strongly delayed when UV-B and water deficit were applied in combination. In summary, deficit irrigation did not modify the adaptive response of grapevine to UV-B, through the accumulation of MEUVAC. However, combined treatments caused additive effects on berry ripening. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  18. Adaptation to high CO2 concentration in an optimal environment: radiation capture, canopy quantum yield and carbon use efficiency

    Science.gov (United States)

    Monje, O.; Bugbee, B.

    1998-01-01

    The effect of elevated [CO2] on wheat (Triticum aestivum L. Veery 10) productivity was examined by analysing radiation capture, canopy quantum yield, canopy carbon use efficiency, harvest index and daily C gain. Canopies were grown at either 330 or 1200 micromoles mol-1 [CO2] in controlled environments, where root and shoot C fluxes were monitored continuously from emergence to harvest. A rapidly circulating hydroponic solution supplied nutrients, water and root zone oxygen. At harvest, dry mass predicted from gas exchange data was 102.8 +/- 4.7% of the observed dry mass in six trials. Neither radiation capture efficiency nor carbon use efficiency were affected by elevated [CO2], but yield increased by 13% due to a sustained increase in canopy quantum yield. CO2 enrichment increased root mass, tiller number and seed mass. Harvest index and chlorophyll concentration were unchanged, but CO2 enrichment increased average life cycle net photosynthesis (13%, P < 0.05) and root respiration (24%, P < 0.05). These data indicate that plant communities adapt to CO2 enrichment through changes in C allocation. Elevated [CO2] increases sink strength in optimal environments, resulting in sustained increases in photosynthetic capacity, canopy quantum yield and daily C gain throughout the life cycle.

  19. Deformable registration of the planning image (kVCT) and the daily images (MVCT) for adaptive radiation therapy

    International Nuclear Information System (INIS)

    Lu Weiguo; Olivera, Gustavo H; Chen, Quan; Ruchala, Kenneth J; Haimerl, Jason; Meeks, Sanford L; Langen, Katja M; Kupelian, Patrick A

    2006-01-01

    The incorporation of daily images into the radiotherapy process leads to adaptive radiation therapy (ART), in which the treatment is evaluated periodically and the plan is adaptively modified for the remaining course of radiotherapy. Deformable registration between the planning image and the daily images is a key component of ART. In this paper, we report our researches on deformable registration between the planning kVCT and the daily MVCT image sets. The method is based on a fast intensity-based free-form deformable registration technique. Considering the noise and contrast resolution differences between the kVCT and the MVCT, an 'edge-preserving smoothing' is applied to the MVCT image prior to the deformable registration process. We retrospectively studied daily MVCT images from commercial TomoTherapy machines from different clinical centers. The data set includes five head-neck cases, one pelvis case, two lung cases and one prostate case. Each case has one kVCT image and 20-40 MVCT images. We registered the MVCT images with their corresponding kVCT image. The similarity measures and visual inspections of contour matches by physicians validated this technique. The applications of deformable registration in ART, including 'deformable dose accumulation', 'automatic re-contouring' and 'tumour growth/regression evaluation' throughout the course of radiotherapy are also studied

  20. Predictable variation of range-sizes across an extreme environmental gradient in a lizard adaptive radiation: evolutionary and ecological inferences.

    Directory of Open Access Journals (Sweden)

    Daniel Pincheira-Donoso

    Full Text Available Large-scale patterns of current species geographic range-size variation reflect historical dynamics of dispersal and provide insights into future consequences under changing environments. Evidence suggests that climate warming exerts major damage on high latitude and elevation organisms, where changes are more severe and available space to disperse tracking historical niches is more limited. Species with longer generations (slower adaptive responses, such as vertebrates, and with restricted distributions (lower genetic diversity, higher inbreeding in these environments are expected to be particularly threatened by warming crises. However, a well-known macroecological generalization (Rapoport's rule predicts that species range-sizes increase with increasing latitude-elevation, thus counterbalancing the impact of climate change. Here, I investigate geographic range-size variation across an extreme environmental gradient and as a function of body size, in the prominent Liolaemus lizard adaptive radiation. Conventional and phylogenetic analyses revealed that latitudinal (but not elevational ranges significantly decrease with increasing latitude-elevation, while body size was unrelated to range-size. Evolutionarily, these results are insightful as they suggest a link between spatial environmental gradients and range-size evolution. However, ecologically, these results suggest that Liolaemus might be increasingly threatened if, as predicted by theory, ranges retract and contract continuously under persisting climate warming, potentially increasing extinction risks at high latitudes and elevations.

  1. Multilocus Species Trees Show the Recent Adaptive Radiation of the Mimetic Heliconius Butterflies

    Science.gov (United States)

    Kozak, Krzysztof M.; Wahlberg, Niklas; Neild, Andrew F. E.; Dasmahapatra, Kanchon K.; Mallet, James; Jiggins, Chris D.

    2015-01-01

    Müllerian mimicry among Neotropical Heliconiini butterflies is an excellent example of natural selection, associated with the diversification of a large continental-scale radiation. Some of the processes driving the evolution of mimicry rings are likely to generate incongruent phylogenetic signals across the assemblage, and thus pose a challenge for systematics. We use a data set of 22 mitochondrial and nuclear markers from 92% of species in the tribe, obtained by Sanger sequencing and de novo assembly of short read data, to re-examine the phylogeny of Heliconiini with both supermatrix and multispecies coalescent approaches, characterize the patterns of conflicting signal, and compare the performance of various methodological approaches to reflect the heterogeneity across the data. Despite the large extent of reticulate signal and strong conflict between markers, nearly identical topologies are consistently recovered by most of the analyses, although the supermatrix approach failed to reflect the underlying variation in the history of individual loci. However, the supermatrix represents a useful approximation where multiple rare species represented by short sequences can be incorporated easily. The first comprehensive, time-calibrated phylogeny of this group is used to test the hypotheses of a diversification rate increase driven by the dramatic environmental changes in the Neotropics over the past 23 myr, or changes caused by diversity-dependent effects on the rate of diversification. We find that the rate of diversification has increased on the branch leading to the presently most species-rich genus Heliconius, but the change occurred gradually and cannot be unequivocally attributed to a specific environmental driver. Our study provides comprehensive comparison of philosophically distinct species tree reconstruction methods and provides insights into the diversification of an important insect radiation in the most biodiverse region of the planet. PMID:25634098

  2. Phylogeny, adaptive radiation, and historical biogeography in Bromeliaceae: insights from an eight-locus plastid phylogeny.

    Science.gov (United States)

    Givnish, Thomas J; Barfuss, Michael H J; Van Ee, Benjamin; Riina, Ricarda; Schulte, Katharina; Horres, Ralf; Gonsiska, Philip A; Jabaily, Rachel S; Crayn, Darren M; Smith, J Andrew C; Winter, Klaus; Brown, Gregory K; Evans, Timothy M; Holst, Bruce K; Luther, Harry; Till, Walter; Zizka, Georg; Berry, Paul E; Sytsma, Kenneth J

    2011-05-01

    Bromeliaceae form a large, ecologically diverse family of angiosperms native to the New World. We use a bromeliad phylogeny based on eight plastid regions to analyze relationships within the family, test a new, eight-subfamily classification, infer the chronology of bromeliad evolution and invasion of different regions, and provide the basis for future analyses of trait evolution and rates of diversification. We employed maximum-parsimony, maximum-likelihood, and Bayesian approaches to analyze 9341 aligned bases for four outgroups and 90 bromeliad species representing 46 of 58 described genera. We calibrate the resulting phylogeny against time using penalized likelihood applied to a monocot-wide tree based on plastid ndhF sequences and use it to analyze patterns of geographic spread using parsimony, Bayesian inference, and the program S-DIVA. Bromeliad subfamilies are related to each other as follows: (Brocchinioideae, (Lindmanioideae, (Tillandsioideae, (Hechtioideae, (Navioideae, (Pitcairnioideae, (Puyoideae, Bromelioideae))))))). Bromeliads arose in the Guayana Shield ca. 100 million years ago (Ma), spread centrifugally in the New World beginning ca. 16-13 Ma, and dispersed to West Africa ca. 9.3 Ma. Modern lineages began to diverge from each other roughly 19 Ma. Nearly two-thirds of extant bromeliads belong to two large radiations: the core tillandsioids, originating in the Andes ca. 14.2 Ma, and the Brazilian Shield bromelioids, originating in the Serro do Mar and adjacent regions ca. 9.1 Ma.

  3. Variation of Human Hairiness: A Possible Adaptation to Solar Radiation and Melanin

    Directory of Open Access Journals (Sweden)

    Dhugga Amrita

    2014-07-01

    Full Text Available Many theories have been advanced to explain human hairlessness, however, there is no consensus. This study of 76 males observed that skin reflectance measuring skin colouration and melanin pigmentation correlated with hair size and follicle density. Individuals with a greater concentration of melanin within the superficial layer of the skin had a lower follicle density and smaller sizes of hairs. In contrast, individuals with a lower melanin concentration and lighter skin colour had a full range of hairiness. This leads to the suggestion that over the course of human evolution, high concentrations of melanin in consistently exposed to ultraviolet radiation areas developed first and that hair loss was a consequence of competition in the skin between melanin production and hair growth. Darker pigmented skin and lower follicle density are significantly correlated (R2=0.283; p<0.05. Individuals with darker skin had a mean of 4.91 follicles per cm2 whereas those with lighter skin reflectance had 11.20 follicles per cm2. This suggests that increased concentrations of melanin in the basal layer of the epidermis may limit hairiness by negatively influencing the skin's ability to produce hair.

  4. TH-A-BRF-02: BEST IN PHYSICS (JOINT IMAGING-THERAPY) - Modeling Tumor Evolution for Adaptive Radiation Therapy

    International Nuclear Information System (INIS)

    Liu, Y; Lee, CG; Chan, TCY; Cho, YB; Islam, MK

    2014-01-01

    was supported in part by the Ontario Consortium for Adaptive Interventions in Radiation Oncology (OCAIRO) funded by the Ontario Research Fund (ORF) and the MITACS Accelerate Internship Program

  5. Radiation

    International Nuclear Information System (INIS)

    Davidson, J.H.

    1986-01-01

    The basic facts about radiation are explained, along with some simple and natural ways of combating its ill-effects, based on ancient healing wisdom as well as the latest biochemical and technological research. Details are also given of the diet that saved thousands of lives in Nagasaki after the Atomic bomb attack. Special comment is made on the use of radiation for food processing. (U.K.)

  6. Radiation dose considerations by intra-individual Monte Carlo simulations in dual source spiral coronary computed tomography angiography with electrocardiogram-triggered tube current modulation and adaptive pitch

    Energy Technology Data Exchange (ETDEWEB)

    May, Matthias S.; Kuettner, Axel; Lell, Michael M.; Wuest, Wolfgang; Scharf, Michael; Uder, Michael [University of Erlangen, Department of Radiology, Erlangen (Germany); Deak, Paul; Kalender, Willi A. [University of Erlangen, Department of Medical Physics, Erlangen (Germany); Keller, Andrea K.; Haeberle, Lothar [University of Erlangen, Department of Medical Informatics, Biometry and Epidemiology, Erlangen (Germany); Achenbach, Stephan; Seltmann, Martin [University of Erlangen, Department of Cardiology, Erlangen (Germany)

    2012-03-15

    To evaluate radiation dose levels in patients undergoing spiral coronary computed tomography angiography (CTA) on a dual-source system in clinical routine. Coronary CTA was performed for 56 patients with electrocardiogram-triggered tube current modulation (TCM) and heart-rate (HR) dependent pitch adaptation. Individual Monte Carlo (MC) simulations were performed for dose assessment. Retrospective simulations with constant tube current (CTC) served as reference. Lung tissue was segmented and used for organ and effective dose (ED) calculation. Estimates for mean relative ED was 7.1 {+-} 2.1 mSv/100 mAs for TCM and 12.5 {+-} 5.3 mSv/100 mAs for CTC (P < 0.001). Relative dose reduction at low HR ({<=}60 bpm) was highest (49 {+-} 5%) compared to intermediate (60-70 bpm, 33 {+-} 12%) and high HR (>70 bpm, 29 {+-} 12%). However lowest ED is achieved at high HR (5.2 {+-} 1.5 mSv/100 mAs), compared with intermediate (6.7 {+-} 1.6 mSv/100 mAs) and low (8.3 {+-} 2.1 mSv/100 mAs) HR when automated pitch adaptation is applied. Radiation dose savings up to 52% are achievable by TCM at low and regular HR. However lowest ED is attained at high HR by pitch adaptation despite inferior radiation dose reduction by TCM. circle Monte Carlo simulations allow for individual radiation dose calculations. (orig.)

  7. γH2AX expression as adaptive response of lymphocyte cells in resident of Takandeang village area with high background natural radiation

    International Nuclear Information System (INIS)

    Iin Kurnia; Teja Kisnanto; Yanti Lusiyanti

    2016-01-01

    Resident that living in high natural radiation has the potential for DNA damage due to exposure to radiation as a part of radiation adaptive response. It has also potentially initiation of genome instability that can cause cancer cell. DNA damage which can be observed with the γH2AX as biomarkers of DNA double strand break. This study aims to determine the expression γH2AX as the adaptive response of lymphocyte of populations living in areas with high natural radiation after being irradiated with challenge dose of 2 Gy. Blood samples from 12 residents were irradiated with 2 Gy and then the detection and counting of γH2AX foci were performed before and after irradiation at 50 lymphocyte cells. From the results study it was found a significant increase in the number of γH2AX foci in lymphocytes after receiving irradiation (p = 0.004). There were no significant differences in the number of γH2AX foci by age and gender either prior to or after irradiation. From this data we can conclude that 2 Gy irradiation directly causes DNA damage as in vitro adaptive response that observed by expression of γH2AX foci. (author)

  8. The adaptive radiation of lichen-forming Teloschistaceae is associated with sunscreening pigments and a bark-to-rock substrate shift.

    Science.gov (United States)

    Gaya, Ester; Fernández-Brime, Samantha; Vargas, Reinaldo; Lachlan, Robert F; Gueidan, Cécile; Ramírez-Mejía, Martín; Lutzoni, François

    2015-09-15

    Adaptive radiations play key roles in the generation of biodiversity and biological novelty, and therefore understanding the factors that drive them remains one of the most important challenges of evolutionary biology. Although both intrinsic innovations and extrinsic ecological opportunities contribute to diversification bursts, few studies have looked at the synergistic effect of such factors. Here we investigate the Teloschistales (Ascomycota), a group of >1,000 lichenized species with variation in species richness and phenotypic traits that hinted at a potential adaptive radiation. We found evidence for a dramatic increase in diversification rate for one of four families within this order--Teloschistaceae--which occurred ∼ 100 Mya (Late Cretaceous) and was associated with a switch from bark to rock and from shady to sun-exposed habitats. This adaptation to sunny habitats is likely to have been enabled by a contemporaneous key novel phenotypic innovation: the production in both vegetative structure (thallus) and fruiting body (apothecia) of anthraquinones, secondary metabolites known to protect against UV light. We found that the two ecological factors (sun exposure and rock substrate) and the phenotypic innovation (anthraquinones in the thallus) were all significant when testing for state-dependent shifts in diversification rates, and together they seem likely to be responsible for the success of the Teloschistaceae, one of the largest lichen-forming fungal lineages. Our results support the idea that adaptive radiations are driven not by a single factor or key innovation, but require a serendipitous combination of both intrinsic biotic and extrinsic abiotic and ecological factors.

  9. Disentangling dispersal, vicariance and adaptive radiation patterns: a case study using armyworms in the pest genus Spodoptera (Lepidoptera: Noctuidae).

    Science.gov (United States)

    Kergoat, Gael J; Prowell, Dorothy P; Le Ru, Bruno P; Mitchell, Andrew; Dumas, Pascaline; Clamens, Anne-Laure; Condamine, Fabien L; Silvain, Jean-François

    2012-12-01

    Thanks to the recent development of integrative approaches that combine dated phylogenies with models of biogeographic evolution, it is becoming more feasible to assess the roles of dispersal and vicariance in creating complex patterns of geographical distribution. However, the historical biogeography of taxa with good dispersal abilities, like birds or flying insects, still remains largely unknown because of the lack of complete phylogenies accompanied by robust estimates of divergence times. In this study, we investigate the evolution and historical biogeography of the globally distributed pest genus Spodoptera (Lepidoptera: Noctuidae) using complete taxon sampling and an extensive set of analyses. Through the analysis of a combined morphological and molecular dataset, we provide the first robust phylogenetic framework for this widespread and economically important group of moths. Historical biogeography approaches indicate that dispersal events have been the driving force in the biogeographic history of the group. One of the most interesting findings of this study is the probable occurrence of two symmetric long-distance dispersal events between the Afrotropical and the Neotropical region, which appear to have occurred in the late Miocene. Even more remarkably, our dated phylogenies reveal that the diversification of the clade that includes specialist grass feeders has followed closely the expansion of grasslands in the Miocene, similar to the adaptive radiation of specialist grazing mammals during the same period. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. Principal component analysis-based anatomical motion models for use in adaptive radiation therapy of head and neck cancer patients

    Science.gov (United States)

    Chetvertkov, Mikhail A.

    Purpose: To develop standard and regularized principal component analysis (PCA) models of anatomical changes from daily cone beam CTs (CBCTs) of head and neck (H&N) patients, assess their potential use in adaptive radiation therapy (ART), and to extract quantitative information for treatment response assessment. Methods: Planning CT (pCT) images of H&N patients were artificially deformed to create "digital phantom" images, which modeled systematic anatomical changes during Radiation Therapy (RT). Artificial deformations closely mirrored patients' actual deformations, and were interpolated to generate 35 synthetic CBCTs, representing evolving anatomy over 35 fractions. Deformation vector fields (DVFs) were acquired between pCT and synthetic CBCTs (i.e., digital phantoms), and between pCT and clinical CBCTs. Patient-specific standard PCA (SPCA) and regularized PCA (RPCA) models were built from these synthetic and clinical DVF sets. Eigenvectors, or eigenDVFs (EDVFs), having the largest eigenvalues were hypothesized to capture the major anatomical deformations during treatment. Modeled anatomies were used to assess the dose deviations with respect to the planned dose distribution. Results: PCA models achieve variable results, depending on the size and location of anatomical change. Random changes prevent or degrade SPCA's ability to detect underlying systematic change. RPCA is able to detect smaller systematic changes against the background of random fraction-to-fraction changes, and is therefore more successful than SPCA at capturing systematic changes early in treatment. SPCA models were less successful at modeling systematic changes in clinical patient images, which contain a wider range of random motion than synthetic CBCTs, while the regularized approach was able to extract major modes of motion. For dose assessment it has been shown that the modeled dose distribution was different from the planned dose for the parotid glands due to their shrinkage and shift into

  11. IMPROVEMENT OF ACCURACY OF RADIATIVE HEAT TRANSFER DIFFERENTIAL APPROXIMATION METHOD FOR MULTI DIMENSIONAL SYSTEMS BY MEANS OF AUTO-ADAPTABLE BOUNDARY CONDITIONS

    Directory of Open Access Journals (Sweden)

    K. V. Dobrego

    2015-01-01

    Full Text Available Differential approximation is derived from radiation transfer equation by averaging over the solid angle. It is one of the more effective methods for engineering calculations of radia- tive heat transfer in complex three-dimensional thermal power systems with selective and scattering media. The new method for improvement of accuracy of the differential approximation based on using of auto-adaptable boundary conditions is introduced in the paper. The  efficiency  of  the  named  method  is  proved  for  the  test  2D-systems.  Self-consistent auto-adaptable boundary conditions taking into consideration the nonorthogonal component of the incident to the boundary radiation flux are formulated. It is demonstrated that taking in- to consideration of the non- orthogonal incident flux in multi-dimensional systems, such as furnaces, boilers, combustion chambers improves the accuracy of the radiant flux simulations and to more extend in the zones adjacent to the edges of the chamber.Test simulations utilizing the differential approximation method with traditional boundary conditions, new self-consistent boundary conditions and “precise” discrete ordinates method were performed. The mean square errors of the resulting radiative fluxes calculated along the boundary of rectangular and triangular test areas were decreased 1.5–2 times by using auto- adaptable boundary conditions. Radiation flux gaps in the corner points of non-symmetric sys- tems are revealed by using auto-adaptable boundary conditions which can not be obtained by using the conventional boundary conditions.

  12. Introduction of online adaptive radiotherapy for bladder cancer through a multicentre clinical trial (Trans-Tasman Radiation Oncology Group 10.01: Lessons learned

    Directory of Open Access Journals (Sweden)

    Daniel Pham

    2013-01-01

    Full Text Available Online adaptive radiotherapy for bladder cancer is a novel radiotherapy technique that was found feasible in a pilot study at a single academic institution. In September 2010 this technique was opened as a multicenter study through the Trans-Tasman Radiation Oncology Group (TROG 10.01 bladder online adaptive radiotherapy treatment. Twelve centers across Australia and New-Zealand registered interest into the trial. A multidisciplinary team of radiation oncologists, radiation therapists and medical physicists represented the trial credentialing and technical support team. To provide timely activation and proper implementation of the adaptive technique the following key areas were addressed at each site: Staff education/training; Practical image guided radiotherapy assessment; provision of help desk and feedback. The trial credentialing process involved face-to-face training and technical problem solving via full day site visits. A dedicated "help-desk" team was developed to provide support for the clinical trial. 26% of the workload occurred at the credentialing period while the remaining 74% came post-center activation. The workload was made up of the following key areas; protocol clarification (36%, technical problems (46% while staff training was less than 10%. Clinical trial credentialing is important to minimizing trial deviations. It should not only focus on site activation quality assurance but also provide ongoing education and technical support.

  13. Introduction of online adaptive radiotherapy for bladder cancer through a multicentre clinical trial (Trans-Tasman Radiation Oncology Group 10.01): lessons learned

    International Nuclear Information System (INIS)

    Pham, Daniel; Roxby, Paul; Kron, Tomas; Rolfo, Aldo; Foroudi, Farshad

    2013-01-01

    Online adaptive radiotherapy for bladder cancer is a novel radiotherapy technique that was found feasible in a pilot study at a single academic institution. In September 2010 this technique was opened as a multicenter study through the Trans-Tasman Radiation Oncology Group (TROG 10.01 bladder online adaptive radiotherapy treatment). Twelve centers across Australia and New-Zealand registered interest into the trial. A multidisciplinary team of radiation oncologists, radiation therapists and medical physicists represented the trial credentialing and technical support team. To provide timely activation and proper implementation of the adaptive technique the following key areas were addressed at each site: Staff education/training; Practical image guided radiotherapy assessment; provision of help desk and feedback. The trial credentialing process involved face-to-face training and technical problem solving via full day site visits. A dedicated 'help-desk' team was developed to provide support for the clinical trial. 26% of the workload occurred at the credentialing period while the remaining 74% came post-center activation. The workload was made up of the following key areas; protocol clarification (36%), technical problems (46%) while staff training was less than 10%. Clinical trial credentialing is important to minimizing trial deviations. It should not only focus on site activation quality assurance but also provide ongoing education and technical support. (author)

  14. Standard and reduced radiation dose liver CT images: adaptive statistical iterative reconstruction versus model-based iterative reconstruction-comparison of findings and image quality.

    Science.gov (United States)

    Shuman, William P; Chan, Keith T; Busey, Janet M; Mitsumori, Lee M; Choi, Eunice; Koprowicz, Kent M; Kanal, Kalpana M

    2014-12-01

    To investigate whether reduced radiation dose liver computed tomography (CT) images reconstructed with model-based iterative reconstruction ( MBIR model-based iterative reconstruction ) might compromise depiction of clinically relevant findings or might have decreased image quality when compared with clinical standard radiation dose CT images reconstructed with adaptive statistical iterative reconstruction ( ASIR adaptive statistical iterative reconstruction ). With institutional review board approval, informed consent, and HIPAA compliance, 50 patients (39 men, 11 women) were prospectively included who underwent liver CT. After a portal venous pass with ASIR adaptive statistical iterative reconstruction images, a 60% reduced radiation dose pass was added with MBIR model-based iterative reconstruction images. One reviewer scored ASIR adaptive statistical iterative reconstruction image quality and marked findings. Two additional independent reviewers noted whether marked findings were present on MBIR model-based iterative reconstruction images and assigned scores for relative conspicuity, spatial resolution, image noise, and image quality. Liver and aorta Hounsfield units and image noise were measured. Volume CT dose index and size-specific dose estimate ( SSDE size-specific dose estimate ) were recorded. Qualitative reviewer scores were summarized. Formal statistical inference for signal-to-noise ratio ( SNR signal-to-noise ratio ), contrast-to-noise ratio ( CNR contrast-to-noise ratio ), volume CT dose index, and SSDE size-specific dose estimate was made (paired t tests), with Bonferroni adjustment. Two independent reviewers identified all 136 ASIR adaptive statistical iterative reconstruction image findings (n = 272) on MBIR model-based iterative reconstruction images, scoring them as equal or better for conspicuity, spatial resolution, and image noise in 94.1% (256 of 272), 96.7% (263 of 272), and 99.3% (270 of 272), respectively. In 50 image sets, two reviewers

  15. Space experiment "Rad Gene"-report 2; Detection of DNA damage and adaptive response activity of human cells exposed to space radiations

    Science.gov (United States)

    Ohnishi, Takeo; Takahashi, Akihisa; Su, Xiaoming; Suzuki, Masao; Tsuruoka, Chizuru; Suzuki, Hiromi; Shimazu, Toru; Seki, Masaya; Hashizume, Toko; Nagamatsu, Aiko; Omori, Katsunori; Ishioka, Noriaki

    To identify DNA damage induced by space radiations such as the high linear energy transfer (LET) particles, phospho-H2AX (γH2AX) foci formation was analyzed in human cells frozen in an International Space Station (ISS) freezer for 133 days. After recovering the frozen sample to the earth, the cells were cultured for 30 min, and then fixed. Here, we show a track of γH2AX positive foci in them by immuno-cytochemical methods. It is suggested that space radiations, especially high LET particles, induced DSBs as a track. From the formation of the tracks in nuclei, exposure dose rate was calculated to be 0.7 mSv per day as relatively high-energy space radiations of Fe-ions (500 MeV/u, 200 keV/µm). From the physical dosimetry with CR-39 and TLD, dose rate was 0.5 mSv per day. These values were similar between biological and physical dosimetries. In addition, the aim of this study was to clarify the effect of space radiations on the radio-adaptive response. After the frozen samples were returned to earth, the cells were cultured for 6 h, and then exposed to challenging X-irradiation doses of 1.2 Gy or 2 Gy. Cellular sensitivity, apoptosis, chromosome aberrations and mutation frequencies were scored. In the cells exposed to a space environment, all of radio-adaptive responses such as the induction of radio-resistance and the depression of radiation-induced apoptosis, chromosome aberrations and mutant frequencies investigated here were found in wtp53 cells, but not in the mp53 cells. These results confirmed that the cells exposed to a space environment were likely to the exposed cells to radiation by the specific low dose range (window; 20-100 mSv) which can lead to an adaptive response on ground-base experiments, and that the cells indicated the biological effects from the space-radiation exposure with such low doses in space.

  16. Bentho-pelagic divergence of cichlid feeding architecture was prodigious and consistent during multiple adaptive radiations within African rift-lakes.

    Directory of Open Access Journals (Sweden)

    W James Cooper

    2010-03-01

    Full Text Available How particular changes in functional morphology can repeatedly promote ecological diversification is an active area of evolutionary investigation. The African rift-lake cichlids offer a calibrated time series of the most dramatic adaptive radiations of vertebrate trophic morphology yet described, and the replicate nature of these events provides a unique opportunity to test whether common changes in functional morphology have repeatedly facilitated their ecological success.Specimens from 87 genera of cichlid fishes endemic to Lakes Tanganyka, Malawi and Victoria were dissected in order to examine the functional morphology of cichlid feeding. We quantified shape using geometric morphometrics and compared patterns of morphological diversity using a series of analytical tests. The primary axes of divergence were conserved among all three radiations, and the most prevalent changes involved the size of the preorbital region of the skull. Even the fishes from the youngest of these lakes (Victoria, which exhibit the lowest amount of skull shape disparity, have undergone extensive preorbital evolution relative to other craniofacial traits. Such changes have large effects on feeding biomechanics, and can promote expansion into a wide array of niches along a bentho-pelagic ecomorphological axis.Here we show that specific changes in trophic anatomy have evolved repeatedly in the African rift lakes, and our results suggest that simple morphological alterations that have large ecological consequences are likely to constitute critical components of adaptive radiations in functional morphology. Such shifts may precede more complex shape changes as lineages diversify into unoccupied niches. The data presented here, combined with observations of other fish lineages, suggest that the preorbital region represents an evolutionary module that can respond quickly to natural selection when fishes colonize new lakes. Characterizing the changes in cichlid trophic

  17. Image-guided adaptive radiation therapy (IGART): Radiobiological and dose escalation considerations for localized carcinoma of the prostate

    International Nuclear Information System (INIS)

    Song, William; Schaly, Bryan; Bauman, Glenn; Battista, Jerry; Van Dyk, Jake

    2005-01-01

    The goal of this work was to evaluate the efficacy of various image-guided adaptive radiation therapy (IGART) techniques to deliver and escalate dose to the prostate in the presence of geometric uncertainties. Five prostate patients with 15-16 treatment CT studies each were retrospectively analyzed. All patients were planned with an 18 MV, six-field conformal technique with a 10 mm margin size and an initial prescription of 70 Gy in 35 fractions. The adaptive strategy employed in this work for patient-specific dose escalation was to increase the prescription dose in 2 Gy-per-fraction increments until the rectum normal tissue complication probability (NTCP) reached a level equal to that of the nominal plan NTCP (i.e., iso-NTCP dose escalation). The various target localization techniques simulated were: (1) daily laser-guided alignment to skin tattoo marks that represents treatment without image-guidance, (2) alignment to bony landmarks with daily portal images, and (3) alignment to the clinical target volume (CTV) with daily CT images. Techniques (1) and (3) were resimulated with a reduced margin size of 5 mm to investigate further dose escalation. When delivering the original clinical prescription dose of 70 Gy in 35 fractions, the 'CTV registration' technique yielded the highest tumor control probability (TCP) most frequently, followed by the 'bone registration' and 'tattoo registration' techniques. However, the differences in TCP among the three techniques were minor when the margin size was 10 mm (≤1.1%). Reducing the margin size to 5 mm significantly degraded the TCP values of the 'tattoo registration' technique in two of the five patients, where a large difference was found compared to the other techniques (≤11.8%). The 'CTV registration' technique, however, did maintain similar TCP values compared to their 10 mm margin counterpart. In terms of normal tissue sparing, the technique producing the lowest NTCP varied from patient to patient. Reducing the

  18. TU-AB-202-06: Quantitative Evaluation of Deformable Image Registration in MRI-Guided Adaptive Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Mooney, K; Zhao, T; Green, O; Mutic, S; Yang, D [Washington University School of Medicine, Saint Louis, MO (United States); Duan, Y [University of Missouri, Columbia, Missouri (United States); Zhang, M [Oregon Health and Science University, Portland, Oregon (United States)

    2016-06-15

    Purpose: To assess the performance of the deformable image registration algorithm used for MRI-guided adaptive radiation therapy using image feature analysis. Methods: MR images were collected from five patients treated on the MRIdian (ViewRay, Inc., Oakwood Village, OH), a three head Cobalt-60 therapy machine with an 0.35 T MR system. The images were acquired immediately prior to treatment with a uniform 1.5 mm resolution. Treatment sites were as follows: head/neck, lung, breast, stomach, and bladder. Deformable image registration was performed using the ViewRay software between the first fraction MRI and the final fraction MRI, and the DICE similarity coefficient (DSC) for the skin contours was reported. The SIFT and Harris feature detection and matching algorithms identified point features in each image separately, then found matching features in the other image. The target registration error (TRE) was defined as the vector distance between matched features on the two image sets. Each deformation was evaluated based on comparison of average TRE and DSC. Results: Image feature analysis produced between 2000–9500 points for evaluation on the patient images. The average (± standard deviation) TRE for all patients was 3.3 mm (±3.1 mm), and the passing rate of TRE<3 mm was 60% on the images. The head/neck patient had the best average TRE (1.9 mm±2.3 mm) and the best passing rate (80%). The lung patient had the worst average TRE (4.8 mm±3.3 mm) and the worst passing rate (37.2%). DSC was not significantly correlated with either TRE (p=0.63) or passing rate (p=0.55). Conclusions: Feature matching provides a quantitative assessment of deformable image registration, with a large number of data points for analysis. The TRE of matched features can be used to evaluate the registration of many objects throughout the volume, whereas DSC mainly provides a measure of gross overlap. We have a research agreement with ViewRay Inc.

  19. Low-Dose Ionizing Radiation Affects Mesenchymal Stem Cells via Extracellular Oxidized Cell-Free DNA: A Possible Mediator of Bystander Effect and Adaptive Response

    Directory of Open Access Journals (Sweden)

    V. A. Sergeeva

    2017-01-01

    Full Text Available We have hypothesized that the adaptive response to low doses of ionizing radiation (IR is mediated by oxidized cell-free DNA (cfDNA fragments. Here, we summarize our experimental evidence for this model. Studies involving measurements of ROS, expression of the NOX (superoxide radical production, induction of apoptosis and DNA double-strand breaks, antiapoptotic gene expression and cell cycle inhibition confirm this hypothesis. We have demonstrated that treatment of mesenchymal stem cells (MSCs with low doses of IR (10 cGy leads to cell death of part of cell population and release of oxidized cfDNA. cfDNA has the ability to penetrate into the cytoplasm of other cells. Oxidized cfDNA, like low doses of IR, induces oxidative stress, ROS production, ROS-induced oxidative modifications of nuclear DNA, DNA breaks, arrest of the cell cycle, activation of DNA reparation and antioxidant response, and inhibition of apoptosis. The MSCs pretreated with low dose of irradiation or oxidized cfDNA were equally effective in induction of adaptive response to challenge further dose of radiation. Our studies suggest that oxidized cfDNA is a signaling molecule in the stress signaling that mediates radiation-induced bystander effects and that it is an important component of the development of radioadaptive responses to low doses of IR.

  20. Dose-rate effect of adaptive response of apoptosis and cell cycle progression induced by low-dose ionizing radiation in EL-4 lymphoma cells in vitro

    International Nuclear Information System (INIS)

    Liu Shuchun; Lu Zhe; Li Yanbo; Kang Shunai; Gong Shouliang; Zhao Wenju

    2008-01-01

    Objective: To observe the dose-rate effect of adaptive response of apoptosis and cell cycle progression induced by low-dose ionizing radiation in EL-4 lymphoma cells in vitro in order to reveal the possible mechanism of biological effect and adaptive response induced by low dose radiation. Methods: The experiment was divided into D2 (challenging dose), D1 (inductive dose) + D2 and sham-irradiation groups. EL-4 lymphoma cells were irradiated with D1 (75 mGy, 6.25-200.00 mGy·mm -1 ) and D2(1.5 Gy, 287 mGy·min -1 ), the time interval between D1 and D2 was 6 h. The percentage of apoptosis and each cell cycle phase were measured with flow cytometry. Results: When the dose rates of D1 were 6.25-50.00 mGy·min -1 , the percentages of apoptosis in the D1 + D2 group were significantly lower than those in the D2 group (P 0 /G 1 phase cells decreased significantly (P -1 , D2 is 1.5 Gy (287 mGy·min -1 ), and the time interval between D1 and D2 is 6 h, the adaptive response of apoptosis and cell cycle progression in EL-4 lymphoma cells in vitro could be induced. (authors)

  1. Repeated exposure of human fibroblasts to ionizing radiation reveals an adaptive response that is not mediated by interleukin-6 or TGF-β

    International Nuclear Information System (INIS)

    Dieriks, Birger; De Vos, Winnok; Baatout, Sarah; Van Oostveldt, Patrick

    2011-01-01

    Exposing cells to a low dose can protect them against a subsequent higher exposure. This phenomenon is known as adaptive response and is frequently observed in a variety of cells. Even though similarities are suspected with other non-targeted effects, such as bystander effects, the exact mechanism behind adaptive response is not fully clarified. In this study human primary fibroblasts were tested for their response to ionizing radiation (IR) after administrating a low priming dose (0.1-0.5 Gy). Both the abundance of γH2AX as a marker for double-stranded breaks and the levels of cytokines, secreted in the medium, were monitored in time. Upon challenge, IR-primed cells showed modified γH2AX spot size distributions and altered repair kinetics, consistent with an adaptive response. In addition, 24 h after priming with IR, four cytokines were significantly upregulated in the medium - GM-CSF (1.33x); IL6 (4.24x); IL8 (1.33x); TGF-β (1.46x). In order to mimick the protective effect of IR priming, we primed the cells with either IL6 or TGF-β. This did not elicit an altered γH2AX response as observed in IR-primed cells, indicating that the adaptive response in these primary fibroblasts is regulated in an IL-6 and TGF-β independent manner.

  2. Repeated exposure of human fibroblasts to ionizing radiation reveals an adaptive response that is not mediated by interleukin-6 or TGF-{beta}

    Energy Technology Data Exchange (ETDEWEB)

    Dieriks, Birger, E-mail: birger.dieriks@ugent.be [Bio-imaging and Cytometry Unit, Department of Molecular Biotechnology, Ghent University, Coupure Links 653, 9000 Gent (Belgium); De Vos, Winnok [Bio-imaging and Cytometry Unit, Department of Molecular Biotechnology, Ghent University, Coupure Links 653, 9000 Gent (Belgium); Baatout, Sarah [Bio-imaging and Cytometry Unit, Department of Molecular Biotechnology, Ghent University, Coupure Links 653, 9000 Gent (Belgium); Radiobiology Unit, Laboratory Molecular and Cellular Biology, Radiobiology Unit, Belgian Nuclear Research Center, SCK.CEN, Boeretang 200, 2400 Mol (Belgium); Van Oostveldt, Patrick, E-mail: Patrick.VanOostveldt@UGent.be [Bio-imaging and Cytometry Unit, Department of Molecular Biotechnology, Ghent University, Coupure Links 653, 9000 Gent (Belgium)

    2011-10-01

    Exposing cells to a low dose can protect them against a subsequent higher exposure. This phenomenon is known as adaptive response and is frequently observed in a variety of cells. Even though similarities are suspected with other non-targeted effects, such as bystander effects, the exact mechanism behind adaptive response is not fully clarified. In this study human primary fibroblasts were tested for their response to ionizing radiation (IR) after administrating a low priming dose (0.1-0.5 Gy). Both the abundance of {gamma}H2AX as a marker for double-stranded breaks and the levels of cytokines, secreted in the medium, were monitored in time. Upon challenge, IR-primed cells showed modified {gamma}H2AX spot size distributions and altered repair kinetics, consistent with an adaptive response. In addition, 24 h after priming with IR, four cytokines were significantly upregulated in the medium - GM-CSF (1.33x); IL6 (4.24x); IL8 (1.33x); TGF-{beta} (1.46x). In order to mimick the protective effect of IR priming, we primed the cells with either IL6 or TGF-{beta}. This did not elicit an altered {gamma}H2AX response as observed in IR-primed cells, indicating that the adaptive response in these primary fibroblasts is regulated in an IL-6 and TGF-{beta} independent manner.

  3. Development of an irrigation control device based on solar radiation and its adaptability for cultivation of high soluble solid tomato fruit in root zone restriction culture

    International Nuclear Information System (INIS)

    Nitta, M.; Shibuya, K.; Kubai, K.; Komatsu, H.; Hosokawa, T.; Nakamura, K.

    2009-01-01

    An irrigation control device based on solar radiation was developed to allow automatic irrigation management for high soluble solid tomato fruit production in root zone restriction culture. Its adaptability for long-term cultivation (planting carried out in early September and harvesting ending in late June) of high soluble solid tomato fruit in root zone restriction culture was examined. The following results were obtained: 1. The control device was composed of generally available electronic parts. A change of setting was possible for the irrigation starting point, the irrigation time period, and the once amount of irrigation. For the first irrigation of the day, one of two irrigation control modes can be chosen; the first determines irrigation dependent on the solar radiation after the irrigated time of the previous day. The second mode irrigates at a set time. 2. The correlation between the total integrated solar radiation and the evapotranspiration rate of tomato plants were investigated. Positive correlations were observed for each month from October to June. Moreover, total integrated solar radiation per unit evapotranspiration was different for each month. 3. In long-term cultivation of tomato fruit using this device, the marketable yield of high soluble solid tomato fruit (more than Brix 8%) was 9.7t/10a. 4. This device exhibited the necessary adaptability for use in long-term cultivation of high soluble solid tomato fruit in root zone restriction culture, by changing the set value of the irrigation starting point and the irrigation time period in accordance with the growth period

  4. Initial Characterization of the Growth Stimulation and Heat-Shock-Induced Adaptive Response in Developing Lake Whitefish Embryos after Ionizing Radiation Exposure.

    Science.gov (United States)

    Thome, Christopher; Mitz, Charles; Hulley, Emily N; Somers, Christopher M; Manzon, Richard G; Wilson, Joanna Y; Boreham, Douglas R

    2017-10-01

    Ionizing radiation is known to effect development during early life stages. Lake whitefish (Coregonus clupeaformis) represent a unique model organism for examining such effects. The purpose of this study was to examine how ionizing radiation affects development in lake whitefish embryos and to investigate the presence of an adaptive response induced by heat shock. Acute exposure to 137 Cs gamma rays was administered at five time points corresponding to major developmental stages, with doses ranging from 0.008 to 15.5 Gy. Chronic gamma-ray exposures were delivered throughout embryogenesis within a custom-built irradiator at dose rates between 0.06 and 4.4 mGy/day. Additionally, embryos were given a heat shock of 3, 6 or 9°C prior to a single acute exposure. Radiation effects were assessed based on survival, development rate, morphometric measurements and growth efficiency. Embryos showed high resistance to acute exposures with an LD 50/hatch of 5.0 ± 0.7 Gy immediately after fertilization, increasing to 14.2 ± 0.1 Gy later in development. Chronic irradiation at all dose rates stimulated growth, with treated embryos up to 60% larger in body mass during development compared to unirradiated controls. Chronic irradiation also accelerated the time-to-hatch. A heat shock administered 6 h prior to irradiation reduced mortality by up to 25%. Overall, low-dose chronic irradiation caused growth stimulation in developing lake whitefish embryos and acute radiation mortality was reduced by a heat-shock-induced adaptive response.

  5. Adaptive Control of Sound Radiation from a Plate into an Acoustic Cavity Using Active Piezoelectric-Damping Composites

    National Research Council Canada - National Science Library

    Poh, S

    1999-01-01

    ... and noise control systems. The evaluation process will involve monitoring the vibration and noise radiation of these systems using a scanning laser vibrometer system to be acquired through this DURIP program...

  6. Directed evolution and in silico analysis of reaction centre proteins reveal molecular signatures of photosynthesis adaptation to radiation pressure.

    Directory of Open Access Journals (Sweden)

    Giuseppina Rea

    2011-01-01

    Full Text Available Evolutionary mechanisms adopted by the photosynthetic apparatus to modifications in the Earth's atmosphere on a geological time-scale remain a focus of intense research. The photosynthetic machinery has had to cope with continuously changing environmental conditions and particularly with the complex ionizing radiation emitted by solar flares. The photosynthetic D1 protein, being the site of electron tunneling-mediated charge separation and solar energy transduction, is a hot spot for the generation of radiation-induced radical injuries. We explored the possibility to produce D1 variants tolerant to ionizing radiation in Chlamydomonas reinhardtii and clarified the effect of radiation-induced oxidative damage on the photosynthetic proteins evolution. In vitro directed evolution strategies targeted at the D1 protein were adopted to create libraries of chlamydomonas random mutants, subsequently selected by exposures to radical-generating proton or neutron sources. The common trend observed in the D1 aminoacidic substitutions was the replacement of less polar by more polar amino acids. The applied selection pressure forced replacement of residues more sensitive to oxidative damage with less sensitive ones, suggesting that ionizing radiation may have been one of the driving forces in the evolution of the eukaryotic photosynthetic apparatus. A set of the identified aminoacidic substitutions, close to the secondary plastoquinone binding niche and oxygen evolving complex, were introduced by site-directed mutagenesis in un-transformed strains, and their sensitivity to free radicals attack analyzed. Mutants displayed reduced electron transport efficiency in physiological conditions, and increased photosynthetic performance stability and oxygen evolution capacity in stressful high-light conditions. Finally, comparative in silico analyses of D1 aminoacidic sequences of organisms differently located in the evolution chain, revealed a higher ratio of residues

  7. Multileaf collimator leaf position verification and analysis for adaptive radiation therapy using a video-optical method

    Science.gov (United States)

    Sethna, Sohrab B.

    External beam radiation therapy is commonly used to eliminate and control cancerous tumors. High-energy beams are shaped to match the patient's specific tumor volume, whereby maximizing radiation dose to malignant cells and limiting dose to normal tissue. A multileaf collimator (MLC) consisting of multiple pairs of tungsten leaves is used to conform the radiation beam to the desired treatment field. Advanced treatment methods utilize dynamic MLC settings to conform to multiple treatment fields and provide intensity modulated radiation therapy (IMRT). Future methods would further increase conformity by actively tracking tumor motion caused by patient cardiac and respiratory motion. Leaf position quality assurance for a dynamic MLC is critical as variation between the planned and actual leaf positions could induce significant errors in radiation dose. The goal of this research project is to prototype a video-optical quality assurance system for MLC leaf positions. The system captures light-field images of MLC leaf sequences during dynamic therapy. Image acquisition and analysis software was developed to determine leaf edge positions. The mean absolute difference between QA prototype predicted and caliper measured leaf positions was found to be 0.6 mm with an uncertainty of +/- 0.3 mm. Maximum errors in predicted positions were below 1.0 mm for static fields. The prototype served as a proof of concept for quality assurance of future tumor tracking methods. Specifically, a lung tumor phantom was created to mimic a lung tumor's motion from respiration. The lung tumor video images were superimposed on MLC field video images for visualization and analysis. The toolbox is capable of displaying leaf position, leaf velocity, tumor position, and determining errors between planned and actual treatment fields for dynamic radiation therapy.

  8. Clinical Outcomes of Image Guided Adaptive Hypofractionated Weekly Radiation Therapy for Bladder Cancer in Patients Unsuitable for Radical Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Hafeez, Shaista, E-mail: shaista.hafeez@icr.ac.uk [The Institute of Cancer Research, London (United Kingdom); The Royal Marsden NHS Foundation Trust, Sutton, Surrey (United Kingdom); McDonald, Fiona; Lalondrelle, Susan [The Royal Marsden NHS Foundation Trust, Sutton, Surrey (United Kingdom); McNair, Helen; Warren-Oseni, Karole; Jones, Kelly [The Institute of Cancer Research, London (United Kingdom); The Royal Marsden NHS Foundation Trust, Sutton, Surrey (United Kingdom); Harris, Victoria [The Royal Marsden NHS Foundation Trust, Sutton, Surrey (United Kingdom); Taylor, Helen; Khoo, Vincent [The Royal Marsden NHS Foundation Trust, London (United Kingdom); Thomas, Karen [The Royal Marsden NHS Foundation Trust, Sutton, Surrey (United Kingdom); Hansen, Vibeke; Dearnaley, David; Horwich, Alan; Huddart, Robert [The Institute of Cancer Research, London (United Kingdom); The Royal Marsden NHS Foundation Trust, Sutton, Surrey (United Kingdom)

    2017-05-01

    Purpose and Objectives: We report on the clinical outcomes of a phase 2 study assessing image guided hypofractionated weekly radiation therapy in bladder cancer patients unsuitable for radical treatment. Methods and Materials: Fifty-five patients with T2-T4aNx-2M0-1 bladder cancer not suitable for cystectomy or daily radiation therapy treatment were recruited. A “plan of the day” radiation therapy approach was used, treating the whole (empty) bladder to 36 Gy in 6 weekly fractions. Acute toxicity was assessed weekly during radiation therapy, at 6 and 12 weeks using the Common Terminology Criteria for Adverse Events version 3.0. Late toxicity was assessed at 6 months and 12 months using Radiation Therapy Oncology Group grading. Cystoscopy was used to assess local control at 3 months. Cumulative incidence function was used to determine local progression at 1 at 2 years. Death without local progression was treated as a competing risk. Overall survival was estimated using the Kaplan-Meier method. Results: Median age was 86 years (range, 68-97 years). Eighty-seven percent of patients completed their prescribed course of radiation therapy. Genitourinary and gastrointestinal grade 3 acute toxicity was seen in 18% (10/55) and 4% (2/55) of patients, respectively. No grade 4 genitourinary or gastrointestinal toxicity was seen. Grade ≥3 late toxicity (any) at 6 and 12 months was seen in 6.5% (2/31) and 4.3% (1/23) of patients, respectively. Local control after radiation therapy was 92% of assessed patients (60% total population). Cumulative incidence of local progression at 1 year and 2 years for all patients was 7% (95% confidence interval [CI] 2%-17%) and 17% (95% CI 8%-29%), respectively. Overall survival at 1 year was 63% (95% CI 48%-74%). Conclusion: Hypofractionated radiation therapy delivered weekly with a plan of the day approach offers good local control with acceptable toxicity in a patient population not suitable for radical bladder treatment.

  9. IR-inducible clusterin gene expression: a protein with potential roles in ionizing radiation-induced adaptive responses, genomic instability, and bystander effects

    Energy Technology Data Exchange (ETDEWEB)

    Klokov, Dmitry [Laboratory of Molecular Stress Responses, Department of Radiation Oncology, Case Western Reserve University, 2103 Cornell Road, Wolstein Research Building 3-531, Cleveland, OH 44106-4942 (United States); Criswell, Tracy [Laboratory of Molecular Stress Responses, Department of Radiation Oncology, Case Western Reserve University, 2103 Cornell Road, Wolstein Research Building 3-531, Cleveland, OH 44106-4942 (United States); Program in Molecular and Cellular Basis of Disease, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4942 (United States); Leskov, Konstantin S. [Laboratory of Molecular Stress Responses, Department of Radiation Oncology, Case Western Reserve University, 2103 Cornell Road, Wolstein Research Building 3-531, Cleveland, OH 44106-4942 (United States); Araki, Shinako [Laboratory of Molecular Stress Responses, Department of Radiation Oncology, Case Western Reserve University, 2103 Cornell Road, Wolstein Research Building 3-531, Cleveland, OH 44106-4942 (United States); Mayo, Lindsey [Laboratory of Molecular Stress Responses, Department of Radiation Oncology, Case Western Reserve University, 2103 Cornell Road, Wolstein Research Building 3-531, Cleveland, OH 44106-4942 (United States); Boothman, David A. [Laboratory of Molecular Stress Responses, Department of Radiation Oncology, Case Western Reserve University, 2103 Cornell Road, Wolstein Research Building 3-531, Cleveland, OH 44106-4942 (United States) and Program in Molecular and Cellular Basis of Disease, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4942 (United States)]. E-mail: dab30@po.cwru.edu

    2004-12-02

    Clusterin (CLU) plays numerous roles in mammalian cells after stress. A review of the recent literature strongly suggests potential roles for CLU proteins in low dose ionizing radiation (IR)-inducible adaptive responses, bystander effects, and delayed death and genomic instability. Its most striking and evident feature is the inducibility of the CLU promoter after low, as well as high, doses of IR. Two major forms of CLU, secreted (sCLU) and nuclear (nCLU), possess opposite functions in cellular responses to IR: sCLU is cytoprotective, whereas nCLU (a byproduct of alternative splicing) is a pro-death factor. Recent studies from our laboratory and others demonstrated that down-regulation of sCLU by specific siRNA increased cytotoxic responses to chemotherapy and IR. sCLU was induced after low non-toxic doses of IR (0.02-0.5 Gy) in human cultured cells and in mice in vivo. The low dose inducibility of this survival protein suggests a possible role for sCLU in radiation adaptive responses, characterized by increased cell radioresistance after exposure to low adapting IR doses. Although it is still unclear whether the adaptive response is beneficial or not to cells, survival of damaged cells after IR may lead to genomic instability in the descendants of surviving cells. Recent studies indicate a link between sCLU accumulation and cancer incidence, as well as aging, supporting involvement of the protein in the development of genomic instability. Secreted after IR, sCLU may also alter intracellular communication due to its ability to bind cell surface receptors, such as the TGF-{beta} receptors (types I and II). This interference with signaling pathways may contribute to IR-induced bystander effects. We hypothesize that activation of the TGF-{beta} signaling pathway, which often occurs after IR exposure, can in turn activate the CLU promoter. TGF-{beta} and IR-inducible de novo synthesized sCLU may then bind the TGF-{beta} receptors and suppress downstream growth arrest

  10. Development and evaluation of a training program for therapeutic radiographers as a basis for online adaptive radiation therapy for bladder carcinoma

    International Nuclear Information System (INIS)

    Foroudi, Farshad; Wong, Jacky; Kron, Tomas; Roxby, Paul; Haworth, Annette; Bailey, Alistair; Rolfo, Aldo; Paneghel, Andrea; Styles, Colin; Laferlita, Marcus; Tai, Keen Hun; Williams, Scott; Duchesne, Gillian

    2010-01-01

    Aims: Online adaptive radiotherapy requires a new level of soft tissue anatomy recognition and decision making by therapeutic radiographers at the linear accelerator. We have developed a therapeutic radiographer training workshop encompassing soft tissue matching for an online adaptive protocol for muscle invasive bladder cancer. Our aim is to present the training program, and its evaluation which compares pre and post training staff soft tissue matching and bladder contouring using Cone Beam Computer Tomography (CBCT). Materials and Methods: Prior to commencement of an online adaptive bladder protocol, a staff training program for 33 therapeutic radiographers, with a separate ethics approved evaluation component was developed. A multidisciplinary training program over two days was carried out with a total of 11 h of training, covering imaging technology, pelvic anatomy and protocol specific decision making in both practical and theoretical sessions. The evaluation included both pre training and post training testing of staff. Results: Pre training and post training, the standard deviations in the contoured bladder between participants in left-right direction were 0.64 vs 0.59 cm, superior-inferior 0.89 vs 0.77 cm and anterior-posterior direction was 0.88 vs 0.52 cm respectively. Similarly the standard deviation in the volume contoured decreased from 40.7 cc pre training to 24.5 cc post training. Time taken in contouring was reduced by the training program (19.8 vs 17.2 min) as was the discrepancy in choice of adaptive radiotherapy plans. The greatest reduction in variations in contouring was seen in staff whose pre training had the largest deviations from the reference radiation oncologist contours. Conclusion: A formalized staff training program is feasible, well received by staff and reduces variation in organ matching and contouring. The improvement was particularly noticed in staff who pre training had larger deviations from the reference standard.

  11. A lower dose threshold for the in vivo protective adaptive response to radiation. Tumorigenesis in chronically exposed normal and Trp53 heterozygous C57BL/6 mice

    International Nuclear Information System (INIS)

    Mitchel, R.E.J.; Burchart, P.; Wyatt, H.

    2008-01-01

    Low doses of ionizing radiation to cells and animals may induce adaptive responses that reduce the risk of cancer. However, there are upper dose thresholds above which these protective adaptive responses do not occur. We have now tested the hypothesis that there are similar lower dose thresholds that must be exceeded in order to induce protective effects in vivo. We examined the effects of low dose/low dose rate fractionated exposures on cancer formation in Trp53 normal or cancer-prone Trp53 heterozygous female C57BL/6 mice. Beginning at 6 weeks of age, mice were exposed 5 days/week to single daily doses (0.33 mGy, 0.7 mGy/h) totaling 48, 97 or 146 mGy over 30, 60 or 90 weeks. The exposures for shorter times (up to 60 weeks) appeared to be below the level necessary to induce overall protective adaptive responses in Trp53 normal mice, and detrimental effects (shortened lifespan, increased frequency) evident for only specific tumor types (B- and T-cell lymphomas), were produced. Only when the exposures were continued for 90 weeks did the dose become sufficient to induce protective adaptive responses, balancing the detrimental effects for these specific cancers, and reducing the risk level back to that of the unexposed animals. Detrimental effects were not seen for other tumor types, and a protective effect was seen for sarcomas after 60 weeks of exposure, which was then lost when the exposure continued for 90 weeks. As previously shown for the upper dose threshold for protection by low doses, the lower dose boundary between protection and harm was influenced by Trp53 functionality. Neither protection nor harm was observed in exposed Trp53 heterozygous mice, indicating that reduced Trp53 function raises the lower dose/dose rate threshold for both detrimental and protective tumorigenic effects. (author)

  12. Effects of varying doses of gamma radiation on locally adapted Tradescantia clone 02 (BNL) (Brookhaven National Laboratory)

    International Nuclear Information System (INIS)

    Dimaano, Maritess M.; Imperial V, Maria Angelica Liza

    1999-03-01

    This study determined the effects of gamma radiation on the meiotic cells of Tradescantia bracteata clone 02 (BNL). The flower buds collected were exposed through dosages ranging from 1 Gy to 5 Gy using gamma cell 220 machine (AECL) in a central axis position (c/a) and grown in Peralta's solution for three days. Out of the twenty buds designated for each dosages, ten buds were treated with 0.05% colchicine solution. The occurrence of micronuclei among the irradiated pollen mother cells suggested a linear relation with the quantity of radiation dose. The occurrence of MN among cells increased linearly from 1 Gy until it reached 3 Gy and 4 Gy. Beyond this maximum dose, cells were less responsive to the dose caused by inhibition of cell division, as demonstrated in the buds exposed to 5 Gy. This result was validated through the kruskal-Wallis test, where the computed h value was 3.44 (critical region of X 2 0 . 05 = 9.49) Experimental results also showed chromosomal breaks, sticky chromosomes, and anaphase bridges in the pollen mother cells of irradiated buds. A significant numbers of cells were also found to have micronuclei, which may vary from 1 to 6 per pollen mother cell, and this showed no relationship with radiation dose. (Author)

  13. Parotid Glands Dose–Effect Relationships Based on Their Actually Delivered Doses: Implications for Adaptive Replanning in Radiation Therapy of Head-and-Neck Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, Klaudia U. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Fernandes, Laura L. [Department of Biostatistics, University of Michigan, Ann Arbor, Michigan (United States); Vineberg, Karen A.; McShan, Daniel; Antonuk, Alan E. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Cornwall, Craig [Department of Hospital Dentistry, University of Michigan, Ann Arbor, Michigan (United States); Feng, Mary [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Schipper, Mathew J. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Department of Biostatistics, University of Michigan, Ann Arbor, Michigan (United States); Balter, James M. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Eisbruch, Avraham, E-mail: eisbruch@umich.edu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States)

    2013-11-15

    Purpose: Doses actually delivered to the parotid glands during radiation therapy often exceed planned doses. We hypothesized that the delivered doses correlate better with parotid salivary output than the planned doses, used in all previous studies, and that determining these correlations will help make decisions regarding adaptive radiation therapy (ART) aimed at reducing the delivered doses. Methods and Materials: In this prospective study, oropharyngeal cancer patients treated definitively with chemoirradiation underwent daily cone-beam computed tomography (CBCT) with clinical setup alignment based on the C2 posterior edge. Parotid glands in the CBCTs were aligned by deformable registration to calculate cumulative delivered doses. Stimulated salivary flow rates were measured separately from each parotid gland pretherapy and periodically posttherapy. Results: Thirty-six parotid glands of 18 patients were analyzed. Average mean planned doses was 32 Gy, and differences from planned to delivered mean gland doses were −4.9 to +8.4 Gy, median difference +2.2 Gy in glands in which delivered doses increased relative to planned. Both planned and delivered mean doses were significantly correlated with posttreatment salivary outputs at almost all posttherapy time points, without statistically significant differences in the correlations. Large dispersions (on average, SD 3.6 Gy) characterized the dose–effect relationships for both. The differences between the cumulative delivered doses and planned doses were evident at first fraction (r=.92, P<.0001) because of complex setup deviations (eg, rotations and neck articulations), uncorrected by the translational clinical alignments. Conclusions: After daily translational setup corrections, differences between planned and delivered doses in most glands were small relative to the SDs of the dose–saliva data, suggesting that ART is not likely to gain measurable salivary output improvement in most cases. These differences were

  14. A comparison between radiation therapists and medical specialists in the use of kilovoltage cone-beam computed tomography scans for potential lung cancer radiotherapy target verification and adaptation

    International Nuclear Information System (INIS)

    Watt, Sandie Carolyn; Vinod, Shalini K.; Dimigen, Marion; Descallar, Joseph; Zogovic, Branimere; Atyeo, John; Wallis, Sian; Holloway, Lois C.

    2016-01-01

    Target volume matching using cone-beam computed tomography (CBCT) is the preferred treatment verification method for lung cancer in many centers. However, radiation therapists (RTs) are trained in bony matching and not soft tissue matching. The purpose of this study was to determine whether RTs were equivalent to radiation oncologists (ROs) and radiologists (RDs) in alignment of the treatment CBCT with the gross tumor volume (GTV) defined at planning and in delineating the GTV on the treatment CBCT, as may be necessary for adaptive radiotherapy. In this study, 10 RTs, 1 RO, and 1 RD performed a manual tumor alignment and correction of the planning GTV to a treatment CBCT to generate an isocenter correction distance for 15 patient data sets. Participants also contoured the GTV on the same data sets. The isocenter correction distance and the contoured GTVs from the RTs were compared with the RD and RO. The mean difference in isocenter correction distances was 0.40 cm between the RO and RD, 0.51 cm between the RTs, and RO and 0.42 cm between the RTs and RD. The 95% CIs were smaller than the equivalence limit of 0.5 cm, indicating that the RTs were equivalent to the RO and RD. For GTV delineation comparisons, the RTs were not found to be equivalent to the RD or RO. The alignment of the planning defined GTV and treatment CBCT using soft tissue matching by the RTs has been shown to be equivalent to those by the RO and RD. However, tumor delineation by the RTs on the treatment CBCT was not equivalent to that of the RO and RD. Thus, it may be appropriate for RTs to undertake soft tissue alignment based on CBCT; however, further investigation may be necessary before RTs undertake delineation for adaptive radiotherapy purposes.

  15. A comparison between radiation therapists and medical specialists in the use of kilovoltage cone-beam computed tomography scans for potential lung cancer radiotherapy target verification and adaptation

    Energy Technology Data Exchange (ETDEWEB)

    Watt, Sandie Carolyn, E-mail: sandie.watt@sswahs.gov.au [Liverpool and Macarthur Cancer Therapy Centres, NSW (Australia); University of Sydney, Sydney, NSW (Australia); Ingham Institute for Applied Medical Research, Liverpool, NSW (Australia); Vinod, Shalini K. [Liverpool and Macarthur Cancer Therapy Centres, NSW (Australia); Ingham Institute for Applied Medical Research, Liverpool, NSW (Australia); South Western Sydney Clinical School, The University of New South Wales, Liverpool, NSW (Australia); Department of Radiation Oncology, Prince of Wales Hospital, NSW (Australia); Dimigen, Marion [Department of Radiology, Liverpool Hospital, NSW (Australia); Department of Radiation Oncology, Prince of Wales Hospital, NSW (Australia); Descallar, Joseph [Ingham Institute for Applied Medical Research, Liverpool, NSW (Australia); South Western Sydney Clinical School, The University of New South Wales, Liverpool, NSW (Australia); Zogovic, Branimere [Department of Radiation Oncology, Prince of Wales Hospital, NSW (Australia); Atyeo, John [University of Sydney, Sydney, NSW (Australia); Wallis, Sian [University of Western Sydney, NSW (Australia); Holloway, Lois C. [Liverpool and Macarthur Cancer Therapy Centres, NSW (Australia); University of Sydney, Sydney, NSW (Australia); Institute of Medical Physics, University of Sydney, Sydney, NSW (Australia); Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia. (Australia); Ingham Institute for Applied Medical Research, Liverpool, NSW (Australia)

    2016-04-01

    Target volume matching using cone-beam computed tomography (CBCT) is the preferred treatment verification method for lung cancer in many centers. However, radiation therapists (RTs) are trained in bony matching and not soft tissue matching. The purpose of this study was to determine whether RTs were equivalent to radiation oncologists (ROs) and radiologists (RDs) in alignment of the treatment CBCT with the gross tumor volume (GTV) defined at planning and in delineating the GTV on the treatment CBCT, as may be necessary for adaptive radiotherapy. In this study, 10 RTs, 1 RO, and 1 RD performed a manual tumor alignment and correction of the planning GTV to a treatment CBCT to generate an isocenter correction distance for 15 patient data sets. Participants also contoured the GTV on the same data sets. The isocenter correction distance and the contoured GTVs from the RTs were compared with the RD and RO. The mean difference in isocenter correction distances was 0.40 cm between the RO and RD, 0.51 cm between the RTs, and RO and 0.42 cm between the RTs and RD. The 95% CIs were smaller than the equivalence limit of 0.5 cm, indicating that the RTs were equivalent to the RO and RD. For GTV delineation comparisons, the RTs were not found to be equivalent to the RD or RO. The alignment of the planning defined GTV and treatment CBCT using soft tissue matching by the RTs has been shown to be equivalent to those by the RO and RD. However, tumor delineation by the RTs on the treatment CBCT was not equivalent to that of the RO and RD. Thus, it may be appropriate for RTs to undertake soft tissue alignment based on CBCT; however, further investigation may be necessary before RTs undertake delineation for adaptive radiotherapy purposes.

  16. Simulated Online Adaptive Magnetic Resonance–Guided Stereotactic Body Radiation Therapy for the Treatment of Oligometastatic Disease of the Abdomen and Central Thorax: Characterization of Potential Advantages

    Energy Technology Data Exchange (ETDEWEB)

    Henke, Lauren; Kashani, Rojano; Yang, Deshan; Zhao, Tianyu; Green, Olga; Olsen, Lindsey; Rodriguez, Vivian; Wooten, H. Omar; Li, H. Harold; Hu, Yanle; Bradley, Jeffrey; Robinson, Clifford; Parikh, Parag; Michalski, Jeff; Mutic, Sasa [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri (United States); Olsen, Jeffrey R., E-mail: Jeffrey.R.Olsen@ucdenver.edu [Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado (United States)

    2016-12-01

    Purpose: To characterize potential advantages of online-adaptive magnetic resonance (MR)-guided stereotactic body radiation therapy (SBRT) to treat oligometastatic disease of the non-liver abdomen and central thorax. Methods and Materials: Ten patients treated with RT for unresectable primary or oligometastatic disease of the non-liver abdomen (n=5) or central thorax (n=5) underwent imaging throughout treatment on a clinical MR image guided RT system. The SBRT plans were created on the basis of tumor/organ at risk (OAR) anatomy at initial computed tomography simulation (P{sub I}), and simulated adaptive plans were created on the basis of observed MR image set tumor/OAR “anatomy of the day” (P{sub A}). Each P{sub A} was planned under workflow constraints to simulate online-adaptive RT. Prescribed dose was 50 Gy/5 fractions, with goal coverage of 95% planning target volume (PTV) by 95% of the prescription, subject to hard OAR constraints. The P{sub I} was applied to each MR dataset and compared with P{sub A} to evaluate changes in dose delivered to tumor/OARs, with dose escalation when possible. Results: Hard OAR constraints were met for all P{sub Is} based on anatomy from initial computed tomography simulation, and all P{sub As} based on anatomy from each daily MR image set. Application of the P{sub I} to anatomy of the day caused OAR constraint violation in 19 of 30 cases. Adaptive planning increased PTV coverage in 21 of 30 cases, including 14 cases in which hard OAR constraints were violated by the nonadaptive plan. For 9 P{sub A} cases, decreased PTV coverage was required to meet hard OAR constraints that would have been violated in a nonadaptive setting. Conclusions: Online-adaptive MRI-guided SBRT may allow PTV dose escalation and/or simultaneous OAR sparing compared with nonadaptive SBRT. A prospective clinical trial is underway at our institution to evaluate clinical outcomes of this technique.

  17. Analysis and adaptation of a mathematical model for the prediction of solar radiation; Analisis y adaptacion de un modelo matematico de prediccion de radiacion solar

    Energy Technology Data Exchange (ETDEWEB)

    Zambrano, Lorenzo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1986-12-31

    There is an abundant, reliable, free, source of energy whose use can be planned and besides, practicably inexhaustible: the solar energy. In Mexico it constitutes an important resource, because of its geographical position; for this reason it is fundamental to know it well, either by means of measurements conducted for several years or by mathematical models. These last ones predict with meteorological variables, the values of the solar radiation with acceptable precision. At the Instituto de Investigaciones Electricas (IIE) a model is studied for the prediction of the solar radiation to be adapted to the local conditions of Mexico. It is used in simulation studies of the solar plants functioning and other solar systems. [Espanol] Existe una fuente de energia abundante, confiable, gratuita, cuyo uso puede planearse y, ademas, es practicamente inagotable: la solar. En Mexico constituye un recurso importante, por la posicion geografica del pais; por eso es fundamental conocerlo bien, ya mediante mediciones realizadas durante algunos anos, ya mediante modelos matematicos. Estos ultimos predicen, con datos de variables meteorologicas, los valores de la radiacion solar con precision aceptable. En el Instituto de Investigaciones Electricas (IIE) se estudia un modelo de prediccion de radiacion solar para adaptarlo a las condiciones locales de Mexico. Se usa en estudios de simulacion del funcionamiento de plantas helioelectricas y otros sistemas solares.

  18. Adaptive Divergence in Experimental Populations of Pseudomonas fluorescens. V. Insight into the Niche Specialist Fuzzy Spreader Compels Revision of the Model Pseudomonas Radiation

    Science.gov (United States)

    Ferguson, Gayle C.; Bertels, Frederic; Rainey, Paul B.

    2013-01-01

    Pseudomonas fluorescens is a model for the study of adaptive radiation. When propagated in a spatially structured environment, the bacterium rapidly diversifies into a range of niche specialist genotypes. Here we present a genetic dissection and phenotypic characterization of the fuzzy spreader (FS) morphotype—a type that arises repeatedly during the course of the P. fluorescens radiation and appears to colonize the bottom of static broth microcosms. The causal mutation is located within gene fuzY (pflu0478)—the fourth gene of the five-gene fuzVWXYZ operon. fuzY encodes a β-glycosyltransferase that is predicted to modify lipopolysaccharide (LPS) O antigens. The effect of the mutation is to cause cell flocculation. Analysis of 92 independent FS genotypes showed each to have arisen as the result of a loss-of-function mutation in fuzY, although different mutations have subtly different phenotypic and fitness effects. Mutations within fuzY were previously shown to suppress the phenotype of mat-forming wrinkly spreader (WS) types. This prompted a reinvestigation of FS niche preference. Time-lapse photography showed that FS colonizes the meniscus of broth microcosms, forming cellular rafts that, being too flimsy to form a mat, collapse to the vial bottom and then repeatably reform only to collapse. This led to a reassessment of the ecology of the P. fluorescens radiation. Finally, we show that ecological interactions between the three dominant emergent types (smooth, WS, and FS), combined with the interdependence of FS and WS on fuzY, can, at least in part, underpin an evolutionary arms race with bacteriophage SBW25Φ2, to which mutation in fuzY confers resistance. PMID:24077305

  19. Radiation dose reduction with the adaptive statistical iterative reconstruction (ASIR) technique for chest CT in children: An intra-individual comparison

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Hyun, E-mail: circle1128@yuhs.ac [Department of Radiology and Research Institute of Radiological Science, Severance Children' s Hospital, Yonsei University, College of Medicine, Seoul (Korea, Republic of); Kim, Myung-Joon, E-mail: mjkim@yuhs.ac [Department of Radiology and Research Institute of Radiological Science, Severance Children' s Hospital, Yonsei University, College of Medicine, Seoul (Korea, Republic of); Yoon, Choon-Sik, E-mail: yooncs58@yuhs.ac [Department of Radiology, Gangnam Severance Hospital, Yonsei University, College of Medicine, Seoul (Korea, Republic of); Lee, Mi-Jung, E-mail: mjl1213@yuhs.ac [Department of Radiology and Research Institute of Radiological Science, Severance Children' s Hospital, Yonsei University, College of Medicine, Seoul (Korea, Republic of)

    2012-09-15

    Objective: To retrospectively compare radiation dose and image quality of pediatric chest CT using a routine dose protocol reconstructed with filtered back projection (FBP) (the Routine study) and a low-dose protocol with 50% adaptive statistical iterative reconstruction (ASIR) (the ASIR study). Materials and methods: We retrospectively reviewed chest CT performed in pediatric patients who underwent both the Routine study and the ASIR study on different days between January 2010 and August 2011. Volume CT dose indices (CTDIvol), dose length products (DLP), and effective doses were obtained to estimate radiation dose. The image quality was evaluated objectively as noise measured in the descending aorta and paraspinal muscle, and subjectively by three radiologists for noise, sharpness, artifacts, and diagnostic acceptability using a four-point scale. The paired Student's t-test and the Wilcoxon signed-rank test were used for statistical analysis. Results: Twenty-six patients (M:F = 13:13, mean age 11.7) were enrolled. The ASIR studies showed 60.3%, 56.2%, and 55.2% reductions in CTDIvol (from 18.73 to 7.43 mGy, P < 0.001), DLP (from 307.42 to 134.51 mGy × cm, P < 0.001), and effective dose (from 4.12 to 1.84 mSv, P < 0.001), respectively, compared with the Routine studies. The objective noise was higher in the paraspinal muscle of the ASIR studies (20.81 vs. 16.67, P = 0.004), but was not different in the aorta (18.23 vs. 18.72, P = 0.726). The subjective image quality demonstrated no difference between the two studies. Conclusion: A low-dose protocol with 50% ASIR allows radiation dose reduction in pediatric chest CT by more than 55% while maintaining image quality.

  20. SU-C-BRA-01: Interactive Auto-Segmentation for Bowel in Online Adaptive MRI-Guided Radiation Therapy by Using a Multi-Region Labeling Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Y; Chen, I; Kashani, R; Wan, H; Maughan, N; Muccigrosso, D; Parikh, P [Washington University School of Medicine, Saint Louis, MO (United States)

    2016-06-15

    Purpose: In MRI-guided online adaptive radiation therapy, re-contouring of bowel is time-consuming and can impact the overall time of patients on table. The study aims to auto-segment bowel on volumetric MR images by using an interactive multi-region labeling algorithm. Methods: 5 Patients with locally advanced pancreatic cancer underwent fractionated radiotherapy (18–25 fractions each, total 118 fractions) on an MRI-guided radiation therapy system with a 0.35 Tesla magnet and three Co-60 sources. At each fraction, a volumetric MR image of the patient was acquired when the patient was in the treatment position. An interactive two-dimensional multi-region labeling technique based on graph cut solver was applied on several typical MRI images to segment the large bowel and small bowel, followed by a shape based contour interpolation for generating entire bowel contours along all image slices. The resulted contours were compared with the physician’s manual contouring by using metrics of Dice coefficient and Hausdorff distance. Results: Image data sets from the first 5 fractions of each patient were selected (total of 25 image data sets) for the segmentation test. The algorithm segmented the large and small bowel effectively and efficiently. All bowel segments were successfully identified, auto-contoured and matched with manual contours. The time cost by the algorithm for each image slice was within 30 seconds. For large bowel, the calculated Dice coefficients and Hausdorff distances (mean±std) were 0.77±0.07 and 13.13±5.01mm, respectively; for small bowel, the corresponding metrics were 0.73±0.08and 14.15±4.72mm, respectively. Conclusion: The preliminary results demonstrated the potential of the proposed algorithm in auto-segmenting large and small bowel on low field MRI images in MRI-guided adaptive radiation therapy. Further work will be focused on improving its segmentation accuracy and lessening human interaction.

  1. Discovery of a Giant Chameleon-Like Lizard (Anolis) on Hispaniola and Its Significance to Understanding Replicated Adaptive Radiations.

    Science.gov (United States)

    Mahler, D Luke; Lambert, Shea M; Geneva, Anthony J; Ng, Julienne; Hedges, S Blair; Losos, Jonathan B; Glor, Richard E

    2016-09-01

    We report a new chameleon-like Anolis species from Hispaniola that is ecomorphologically similar to congeners found only on Cuba. Lizards from both clades possess short limbs and a short tail and utilize relatively narrow perches, leading us to recognize a novel example of ecomorphological matching among islands in the well-known Greater Antillean anole radiation. This discovery supports the hypothesis that the assembly of island faunas can be substantially deterministic and highlights the continued potential for basic discovery to reveal new insights in well-studied groups. Restricted to a threatened band of midelevation transitional forest near the border of the Dominican Republic and Haiti, this new species appears to be highly endangered.

  2. Feed-forward adaptive system for vibration and sound radiation reduction phase I: architecture, definition, and specifications

    Science.gov (United States)

    Concilio, Antonio; De Vivo, Luciano; Quaranta, V.

    1998-06-01

    Noise emission suppression problem is more and more absorbing mechanical designers' efforts, in the recent times. It is not only a matter of comfort, but also of people exposure noise limits. A significant step has been moved in Europe with the issue of the EU Green Paper: Future Noise Policy. Impact on external and internal environment is requested to be considered in industrial and civil design. Low frequency disturbances are hard to be treated by classical passive methods. Active noise control presents great potentialities. In the last years, significant improvements have been attained in the field of interior acoustics, with particular reference to aircraft. Microphones and loudspeakers - based active systems have been put on the market, while interesting alternatives have been proved to be effective, implementing Smart Materials and Structures related concepts. The authors of this paper and of its continuation have been working for a long time inside the themes related to the noise control in aircraft cabins. Thin-walled beams have a certain importance; they are representative of fuselage range. This document deals with the design and the specifications definition, concerning a system addressed to the minimization of the vibration level of, or the sound power level radiated by , a general structure; in the specific case, a thin-walled beam was selected as test article, fully representative of general complex elements. The structure is identified and characterized through its experimental response. The set-up for the active control measurements is then described in detail; the acquired transfer functions have been elaborated to predict the performance of the real active control system.

  3. An Atlas-Based Electron Density Mapping Method for Magnetic Resonance Imaging (MRI)-Alone Treatment Planning and Adaptive MRI-Based Prostate Radiation Therapy

    International Nuclear Information System (INIS)

    Dowling, Jason A.; Lambert, Jonathan; Parker, Joel; Salvado, Olivier; Fripp, Jurgen; Capp, Anne; Wratten, Chris; Denham, James W.; Greer, Peter B.

    2012-01-01

    Purpose: Prostate radiation therapy dose planning directly on magnetic resonance imaging (MRI) scans would reduce costs and uncertainties due to multimodality image registration. Adaptive planning using a combined MRI-linear accelerator approach will also require dose calculations to be performed using MRI data. The aim of this work was to develop an atlas-based method to map realistic electron densities to MRI scans for dose calculations and digitally reconstructed radiograph (DRR) generation. Methods and Materials: Whole-pelvis MRI and CT scan data were collected from 39 prostate patients. Scans from 2 patients showed significantly different anatomy from that of the remaining patient population, and these patients were excluded. A whole-pelvis MRI atlas was generated based on the manually delineated MRI scans. In addition, a conjugate electron-density atlas was generated from the coregistered computed tomography (CT)-MRI scans. Pseudo-CT scans for each patient were automatically generated by global and nonrigid registration of the MRI atlas to the patient MRI scan, followed by application of the same transformations to the electron-density atlas. Comparisons were made between organ segmentations by using the Dice similarity coefficient (DSC) and point dose calculations for 26 patients on planning CT and pseudo-CT scans. Results: The agreement between pseudo-CT and planning CT was quantified by differences in the point dose at isocenter and distance to agreement in corresponding voxels. Dose differences were found to be less than 2%. Chi-squared values indicated that the planning CT and pseudo-CT dose distributions were equivalent. No significant differences (p > 0.9) were found between CT and pseudo-CT Hounsfield units for organs of interest. Mean ± standard deviation DSC scores for the atlas-based segmentation of the pelvic bones were 0.79 ± 0.12, 0.70 ± 0.14 for the prostate, 0.64 ± 0.16 for the bladder, and 0.63 ± 0.16 for the rectum. Conclusions: The

  4. Image quality in children with low-radiation chest CT using adaptive statistical iterative reconstruction and model-based iterative reconstruction.

    Directory of Open Access Journals (Sweden)

    Jihang Sun

    Full Text Available OBJECTIVE: To evaluate noise reduction and image quality improvement in low-radiation dose chest CT images in children using adaptive statistical iterative reconstruction (ASIR and a full model-based iterative reconstruction (MBIR algorithm. METHODS: Forty-five children (age ranging from 28 days to 6 years, median of 1.8 years who received low-dose chest CT scans were included. Age-dependent noise index (NI was used for acquisition. Images were retrospectively reconstructed using three methods: MBIR, 60% of ASIR and 40% of conventional filtered back-projection (FBP, and FBP. The subjective quality of the images was independently evaluated by two radiologists. Objective noises in the left ventricle (LV, muscle, fat, descending aorta and lung field at the layer with the largest cross-section area of LV were measured, with the region of interest about one fourth to half of the area of descending aorta. Optimized signal-to-noise ratio (SNR was calculated. RESULT: In terms of subjective quality, MBIR images were significantly better than ASIR and FBP in image noise and visibility of tiny structures, but blurred edges were observed. In terms of objective noise, MBIR and ASIR reconstruction decreased the image noise by 55.2% and 31.8%, respectively, for LV compared with FBP. Similarly, MBIR and ASIR reconstruction increased the SNR by 124.0% and 46.2%, respectively, compared with FBP. CONCLUSION: Compared with FBP and ASIR, overall image quality and noise reduction were significantly improved by MBIR. MBIR image could reconstruct eligible chest CT images in children with lower radiation dose.

  5. SU-F-J-133: Adaptive Radiation Therapy with a Four-Dimensional Dose Calculation Algorithm That Optimizes Dose Distribution Considering Breathing Motion

    Energy Technology Data Exchange (ETDEWEB)

    Ali, I; Algan, O; Ahmad, S [University of Oklahoma Health Sciences, Oklahoma City, OK (United States); Alsbou, N [University of Central Oklahoma, Edmond, OK (United States)

    2016-06-15

    techniques such as beam-gating or breath-holding and has potential applications in adaptive radiation therapy.

  6. Adaptations of the reed frog Hyperolius viridiflavus (Amphibia: Anura: Hyperoliidae) to its arid environment. VI. The iridophores in the skin as radiation reflectors.

    Science.gov (United States)

    Kobelt, F; Linsenmair, K E

    1992-01-01

    Hyperolius viridiflavus possesses one complete layer of iridophores in the stratum spongiosum of its skin at about 8 days after metamorphosis. The high reflectance of this thin layer is almost certainly the result of multilayer interference reflection. In order to reflect a mean of about 35% of the incident radiation across a spectrum of 300-2900 nm only 30 layers of well-arranged crystals are required, resulting in a layer 10.5 microns thick. These theoretical values are in good agreement with the actual mean diameter of single iridophores (15.0 +/- 3.0 microns), the number of stacked platelets (40-100) and the measured reflectance of one complete layer of these cells (32.2 +/- 2.3%). Iridescence colours typical of multilayer interference reflectors were seen after severe dehydration. The skin colour turned from white (0-10% weight loss) through a copper-like iridescence (10-25% weight loss) to green iridescence (25-42%). In dry season state, H. viridiflavus needs a much higher reflectance to cope with the problems of high solar radiation load during long periods with severe dehydration stress. Dry-adapted skin contains about 4-6 layers of iridophores. The measured reflectance (up to 60% across the solar spectrum) of this thick layer (over 60 microns) is not in keeping with the results obtained by applying the multilayer interference theory. Light, scattered independently of wavelength from disordered crystals, superimposes on the multilayer-induced spectral reflectance. The initial parallel shift of the multilayer curves with increasing thickness and the almost constant ("white") reflectance of layers exceeding 60 microns clearly point to a changing physical basis with increasing layer thickness.

  7. Adaptive statistical iterative reconstruction-applied ultra-low-dose CT with radiography- comparable radiation dose: Usefulness for lung nodule detection

    International Nuclear Information System (INIS)

    Yoon, Hyun Jung; Chung, Myung Jin; Hwang, Hye Sun; Lee, Kyung Soo; Moon, Jung Won

    2015-01-01

    To assess the performance of adaptive statistical iterative reconstruction (ASIR)-applied ultra-low-dose CT (ULDCT) in detecting small lung nodules. Thirty patients underwent both ULDCT and standard dose CT (SCT). After determining the reference standard nodules, five observers, blinded to the reference standard reading results, independently evaluated SCT and both subsets of ASIR- and filtered back projection (FBP)-driven ULDCT images. Data assessed by observers were compared statistically. Converted effective doses in SCT and ULDCT were 2.81 ± 0.92 and 0.17 ± 0.02 mSv, respectively. A total of 114 lung nodules were detected on SCT as a standard reference. There was no statistically significant difference in sensitivity between ASIR-driven ULDCT and SCT for three out of the five observers (p = 0.678, 0.735, < 0.01, 0.038, and < 0.868 for observers 1, 2, 3, 4, and 5, respectively). The sensitivity of FBP-driven ULDCT was significantly lower than that of ASIR-driven ULDCT in three out of the five observers (p < 0.01 for three observers, and p = 0.064 and 0.146 for two observers). In jackknife alternative free-response receiver operating characteristic analysis, the mean values of figure-of-merit (FOM) for FBP, ASIR-driven ULDCT, and SCT were 0.682, 0.772, and 0.821, respectively, and there were no significant differences in FOM values between ASIR-driven ULDCT and SCT (p = 0.11), but the FOM value of FBP-driven ULDCT was significantly lower than that of ASIR-driven ULDCT and SCT (p = 0.01 and 0.00). Adaptive statistical iterative reconstruction-driven ULDCT delivering a radiation dose of only 0.17 mSv offers acceptable sensitivity in nodule detection compared with SCT and has better performance than FBP-driven ULDCT

  8. In vitro techniques for selection of radiation induced mutations adapted to adverse environmental conditions. Proceedings of a final research co-ordination meeting

    International Nuclear Information System (INIS)

    2001-06-01

    The ever increasing human population and dwindling land and water resources worldwide make it essential to produce more food, fibre and fodder from less and less land. During the last century, plant breeding contributed remarkably to increasing food by producing varieties which give higher yield, have improved quality and nutrition, and resist diseases and pests. Nearly 50% of the increase in food production in Asia during the last fifty years can be attributed to the high yielding, short height varieties of rice and wheat, the remaining to the improved agronomic inputs and management. Many crops, such as cassava, potato, pineapple, sweet potato, sugarcane, banana and plantain are major food crops, and others such as sugarcane and pineapple are important to the economies of many developing countries. One of the solutions to have a sustainable and secure food production is to breed varieties which are tolerant of stress conditions during their growth and development. Hence a Co-ordinated Research Project on In vitro Techniques for Selection of Radiation Induced Mutations Adapted to Adverse Environmental Conditions was initiated and focused primarily on the improvement of vegetatively propagated plants. Since the inception of this project, several participating scientists established the optimal dose requirement for in vitro cultured material. Investigations were carried out on the effect of radiation to alter traits which affect survival under stress conditions and high temperature stress in potato, pineapple, sweet potato and garlic. The possibility to change traits such as tolerance to saline and water logged soils in sugarcane and gene regulation for salinity tolerance were studied. The limited number of available reports suggest that callus cultures are much more sensitive to radiation treatment and require much lower doses (2 to 5 Gy) than stem cuttings or seeds, and that relatively higher doses (15 to 20 Gy) cause necrosis or loss of regenerative capacity. The

  9. A survey of the signal stability and radiation dose response of sulfates in the context of adapting optical dating for Mars

    International Nuclear Information System (INIS)

    O'Connor, V.A.; Lepper, K.; Morken, T.O.; Thorstad, D.J.; Podoll, A.; Giles, M.J.

    2011-01-01

    The Martian landscape is currently dominated by eolian processes, and eolian dunes are a direct geomorphic expression of the dynamic interaction between the atmosphere and the lithosphere of planets. The timing, frequency, and spatial extent of dune mobility directly reflects changing climatic conditions, therefore, sedimentary depositional ages are important for understanding the paleoclimatic and geomorphologic history of features and processes present on the surface of the Earth or Mars. Optical dating is an established terrestrial dosimetric dating technique that is being developed for this task on Mars. Gypsum and anhydrite are two of the most stable and abundant sulfate species found on the Earth, and they have been discovered in Martian sediments along with various magnesium sulfates and jarosite. In this study, the optical dating properties of various Ca-, Mg-, and Fe-bearing sulfates were documented to help evaluate the influence they may have on in-situ optical dating in eolian environments on Mars. Single-aliquot regenerative-dose (SAR) experimental procedures have been adapted to characterize the radiation dose response and signal stability of the Martian sulfate analogs. Jarosite was dosimetrically inert in our experiments. The radiation dose response of the Ca- and Mg-sulfates was monotonically increasing in all cases with characteristic doses ranging from ∼100 to ∼1000 Gy. Short-term signal fading also varied considerably in the Ca- and Mg-sulfates ranging from ∼0% to ∼40% per decade for these materials. These results suggest that the OSL properties of Ca- and Mg-sulfates will need to be considered when developing protocols for in-situ optical dating on Mars, but more enticingly, our results foreshadow the potential for gypsum to be developed as a geochronometer for Mars or the Earth. - Highlights: → The radiation dose response and OSL signal stability of Ca- and Mg-sulfates was highly variable. → OSL properties of Ca- and Mg

  10. Detection of genomic instability in descendants of male mice exposed to chronic low-level gamma-radiation using the test 'adaptive response'

    International Nuclear Information System (INIS)

    Rozanova, O.M.; Zaichkina, S.I.; Akhmadieva, A.; Aptikaeva, G.F.; Klokov, D.J.

    2003-01-01

    Full text: The goal of the present study was to examine whether the genomic instability can be revealed in vivo using the test 'adaptive response' (AR). Two-month-old BALB/C male mice were subjected to chronic irradiation in the gamma-field with a dose of 0.1 Gy (0.01 Gy/day) and a dose of 0.5 Gy (0.01 and 0.05 Gy/day). Control animals were kept under similar conditions but without irradiation. Fifteen days after the irradiation, males from the irradiated and control groups were mated in separate cages with unirradiated females for 2 weeks. The males, descendants from irradiated and unirradiated parents, at an age of two months were subjected to additional irradiation with a dose of 1.5 Gy. To reveal the genetic instability using the AR test, another group of males, the descendants from irradiated and unirradiated parents, were exposed to acute irradiation by the scheme of AR: with an adapting dose (D1) of 0.1 Gy (0.125 Gy/min) followed after a day by a challenging dose (D2) of 1.5 Gy (0.47 Gy/min). After 28 h, the animals of all groups were killed. Bone marrow specimens for calculating micronuclei (MN) in polychromatophyl erythrocytes (PCE) were prepared. It was found that in descendants that resulted from unirradiated parents and the parents irradiated with a dose of 0.1 Gy, the percentages of PCE with injuries were nearly equal. Upon irradiation of parents with a dose of 0.5 Gy, the percentage of PCE with MN in descendants increased. The examination of radiosensitivity of descendants from irradiated parents showed that the percentage of PCE with MN decreased three-to-fourfold (depending on the dose of irradiation of the parents) compared to descendants from unirradiated parents. If the descendants from exposed parents were irradiated by the scheme of AR, no AR was observed. Thus, the experimental data indicated that, it is possible to detect the transition of gamma-radiation-induced genomic instability in sex cells of male parents into somatic cells of mice (F1

  11. Interval for the expression of the adaptive response induced by gamma radiation in leucocytes of mouse In vivo; Intervalo para la expresion de la respuesta adaptativa inducida por radiacion gamma en leucocitos de raton In vivo

    Energy Technology Data Exchange (ETDEWEB)

    Mendiola C, M.T.; Morales R, P. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2002-07-01

    The interval between the adaptive gamma radiation dose (0.01 Gy) and challenge (1.0 Gy) capable to induce the maximum expression of the adaptive response in lymphocytes of mouse In vivo. The animals were exposed to the mentioned doses with different intervals among both (1, 1.5, 5 or 18 hr). By means of the unicellular electrophoresis in gel technique, four damage parameters were analysed. The results showed that from the 1 hr interval an adaptive response was produced since in the pretreated organisms with 0.01 Gy the cells present lesser damage than in those not adapted. The maximum response was induced with the intervals between 2.5 and 5 hr and even though it persisted until 18 hr, the effect was reducing. (Author)

  12. Adaptive radiation of Pseudomonas fluorescens SBW25 in experimental microcosms provides an understanding of the evolutionary ecology and molecular biology of A-L interface biofilm formation.

    Science.gov (United States)

    Koza, Anna; Kusmierska, Anna; McLaughlin, Kimberley; Moshynets, Olena; Spiers, Andrew J

    2017-07-03

    Combined experimental evolutionary and molecular biology approaches have been used to investigate the adaptive radiation of Pseudomonas fluorescens SBW25 in static microcosms leading to the colonisation of the air-liquid interface by biofilm-forming mutants such as the Wrinkly Spreader (WS). In these microcosms, the ecosystem engineering of the early wild-type colonists establishes the niche space for subsequent WS evolution and colonisation. Random WS mutations occurring in the developing population that deregulate diguanylate cyclases and c-di-GMP homeostasis result in cellulose-based biofilms at the air-liquid interface. These structures allow Wrinkly Spreaders to intercept O2 diffusing into the liquid column and limit the growth of competitors lower down. As the biofilm matures, competition increasingly occurs between WS lineages, and niche divergence within the biofilm may support further diversification before system failure when the structure finally sinks. A combination of pleiotropic and epistasis effects, as well as secondary mutations, may explain variations in WS phenotype and fitness. Understanding how mutations subvert regulatory networks to express intrinsic genome potential and key innovations providing a selective advantage in novel environments is key to understanding the versatility of bacteria, and how selection and ecological opportunity can rapidly lead to substantive changes in phenotype and in community structure and function. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. MO-D-BRB-09: Treatment Delivery QA for Online Adaptive Radiation Therapy Based on Dynamic Machine Information (DMI): A Feasibility Study.

    Science.gov (United States)

    Li, T; Yuan, L; Wu, Q; Yin, F; Wu, Q J

    2012-06-01

    To implement a quality assurance (QA) system for the treatment delivery of online adaptive radiation therapy utilizing Dynamic Machine Information (DMI). DMI provides the expected/actual MLC leaf-positions, delivered MU, and beam-on status every 50ms during delivery. In this study a stream of DMI inputs is simulated by playing back Dynalog information recorded while delivering a test fluence map (FM). Based on these DMI inputs, the QA system performs three levels of monitoring/verification on the plan delivery process: (1) Following each input, actual and expected FMs delivered up to the current MLC position is dynamically updated using corresponding MLC positions in the DMI. The magnitude and frequency of pixel-by-pixel fluence differences between these two FMs are calculated and visualized in histograms.(2) At each control point, actual MLC positions are verified against the treatment plan for potential errors in data transfer between the treatment planning system (TPS) and the MLC controller.(3) Both (1) and (2) can signal beam-hold with a user-specified error tolerance.(4) After treatment, delivered dose is reconstructed in TPS based on DMI data during delivery, and compared to planned dose. (1) Efficiency: Average latency from DMI input to the completion of fluence difference calculation is Varian) Research partially supported by Varian Medical Systems. © 2012 American Association of Physicists in Medicine.

  14. Does adaptive radiation of a host lineage promote ecological diversity of its bacterial communities? A test using gut microbiota of Anolis lizards.

    Science.gov (United States)

    Ren, Tiantian; Kahrl, Ariel F; Wu, Martin; Cox, Robert M

    2016-10-01

    Adaptive radiations provide unique opportunities to test whether and how recent ecological and evolutionary diversification of host species structures the composition of entire bacterial communities. We used 16S rRNA gene sequencing of faecal samples to test for differences in the gut microbiota of six species of Puerto Rican Anolis lizards characterized by the evolution of distinct 'ecomorphs' related to differences in habitat use. We found substantial variation in the composition of the microbiota within each species and ecomorph (trunk-crown, trunk-ground, grass-bush), but no differences in bacterial alpha diversity among species or ecomorphs. Beta diversity analyses revealed subtle but significant differences in bacterial composition related to host phylogeny and species, but these differences were not consistently associated with Anolis ecomorph. Comparison of a trunk-ground species from this clade (A. cristatellus) with a distantly related member of the same ecomorph class (A. sagrei) where the two species have been introduced and are now sympatric in Florida revealed pronounced differences in the alpha diversity and beta diversity of their microbiota despite their ecological similarity. Comparisons of these populations with allopatric conspecifics also revealed geographic differences in bacterial alpha diversity and beta diversity within each species. Finally, we observed high intraindividual variation over time and strong effects of a simplified laboratory diet on the microbiota of A. sagrei. Collectively, our results indicate that bacterial communities are only weakly shaped by the diversification of their lizard hosts due to the strikingly high levels of bacterial diversity and variation observed within Anolis species. © 2016 John Wiley & Sons Ltd.

  15. Feasibility study of radiation dose reduction in adult female pelvic CT scan with low tube-voltage and adaptive statistical iterative econstruction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xin Lian; He, Wen; Chen, Jian Hong; Hu, Zhi Hai; Zhao, Li Qin [Dept. of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing (China)

    2015-10-15

    To evaluate image quality of female pelvic computed tomography (CT) scans reconstructed with the adaptive statistical iterative reconstruction (ASIR) technique combined with low tube-voltage and to explore the feasibility of its clinical application. Ninety-four patients were divided into two groups. The study group used 100 kVp, and images were reconstructed with 30%, 50%, 70%, and 90% ASIR. The control group used 120 kVp, and images were reconstructed with 30% ASIR. The noise index was 15 for the study group and 11 for the control group. The CT values and noise levels of different tissues were measured. The contrast to noise ratio (CNR) was calculated. A subjective evaluation was carried out by two experienced radiologists. The CT dose index volume (CTDIvol) was recorded. A 44.7% reduction in CTDIvol was observed in the study group (8.18 ± 3.58 mGy) compared with that in the control group (14.78 ± 6.15 mGy). No significant differences were observed in the tissue noise levels and CNR values between the 70% ASIR group and the control group (p = 0.068-1.000). The subjective scores indicated that visibility of small structures, diagnostic confidence, and the overall image quality score in the 70% ASIR group was the best, and were similar to those in the control group (1.87 vs. 1.79, 1.26 vs. 1.28, and 4.53 vs. 4.57; p = 0.122-0.585). No significant difference in diagnostic accuracy was detected between the study group and the control group (42/47 vs. 43/47, p = 1.000). Low tube-voltage combined with automatic tube current modulation and 70% ASIR allowed the low CT radiation dose to be reduced by 44.7% without losing image quality on female pelvic scan.

  16. Potential dosimetric benefits of adaptive tumor tracking over the internal target volume concept for stereotactic body radiation therapy of pancreatic cancer.

    Science.gov (United States)

    Karava, Konstantina; Ehrbar, Stefanie; Riesterer, Oliver; Roesch, Johannes; Glatz, Stefan; Klöck, Stephan; Guckenberger, Matthias; Tanadini-Lang, Stephanie

    2017-11-09

    Radiotherapy for pancreatic cancer has two major challenges: (I) the tumor is adjacent to several critical organs and, (II) the mobility of both, the tumor and its surrounding organs at risk (OARs). A treatment planning study simulating stereotactic body radiation therapy (SBRT) for pancreatic tumors with both the internal target volume (ITV) concept and the tumor tracking approach was performed. The two respiratory motion-management techniques were compared in terms of doses to the target volume and organs at risk. Two volumetric-modulated arc therapy (VMAT) treatment plans (5 × 5 Gy) were created for each of the 12 previously treated pancreatic cancer patients, one using the ITV concept and one the tumor tracking approach. To better evaluate the overall dose delivered to the moving tumor volume, 4D dose calculations were performed on four-dimensional computed tomography (4DCT) scans. The resulting planning target volume (PTV) size for each technique was analyzed. Target and OAR dose parameters were reported and analyzed for both 3D and 4D dose calculation. Tumor motion ranged from 1.3 to 11.2 mm. Tracking led to a reduction of PTV size (max. 39.2%) accompanied with significant better tumor coverage (p<0.05, paired Wilcoxon signed rank test) both in 3D and 4D dose calculations and improved organ at risk sparing. Especially for duodenum, stomach and liver, the mean dose was significantly reduced (p<0.05) with tracking for 3D and 4D dose calculations. By using an adaptive tumor tracking approach for respiratory-induced pancreatic motion management, a significant reduction in PTV size can be achieved, which subsequently facilitates treatment planning, and improves organ dose sparing. The dosimetric benefit of tumor tracking is organ and patient-specific.

  17. Correction for ‘artificial’ electron disequilibrium due to cone-beam CT density errors: implications for on-line adaptive stereotactic body radiation therapy of lung

    International Nuclear Information System (INIS)

    Disher, Brandon; Hajdok, George; Craig, Jeff; Gaede, Stewart; Battista, Jerry J; Wang, An

    2013-01-01

    Cone-beam computed tomography (CBCT) has rapidly become a clinically useful imaging modality for image-guided radiation therapy. Unfortunately, CBCT images of the thorax are susceptible to artefacts due to scattered photons, beam hardening, lag in data acquisition, and respiratory motion during a slow scan. These limitations cause dose errors when CBCT image data are used directly in dose computations for on-line, dose adaptive radiation therapy (DART). The purpose of this work is to assess the magnitude of errors in CBCT numbers (HU), and determine the resultant effects on derived tissue density and computed dose accuracy for stereotactic body radiation therapy (SBRT) of lung cancer. Planning CT (PCT) images of three lung patients were acquired using a Philips multi-slice helical CT simulator, while CBCT images were obtained with a Varian On-Board Imaging system. To account for erroneous CBCT data, three practical correction techniques were tested: (1) conversion of CBCT numbers to electron density using phantoms, (2) replacement of individual CBCT pixel values with bulk CT numbers, averaged from PCT images for tissue regions, and (3) limited replacement of CBCT lung pixels values (LCT) likely to produce artificial lateral electron disequilibrium. For each corrected CBCT data set, lung SBRT dose distributions were computed for a 6 MV volume modulated arc therapy (VMAT) technique within the Philips Pinnacle treatment planning system. The reference prescription dose was set such that 95% of the planning target volume (PTV) received at least 54 Gy (i.e. D95). Further, we used the relative depth dose factor as an a priori index to predict the effects of incorrect low tissue density on computed lung dose in regions of severe electron disequilibrium. CT number profiles from co-registered CBCT and PCT patient lung images revealed many reduced lung pixel values in CBCT data, with some pixels corresponding to vacuum (−1000 HU). Similarly, CBCT data in a plastic lung

  18. SU-D-202-01: Functional Lung Avoidance and Response-Adaptive Escalation (FLARE) RT: Feasibility of a Precision Radiation Oncology Strategy

    International Nuclear Information System (INIS)

    Bowen, S; Lee, E; Miyaoka, R; Kinahan, P; Sandison, G; Vesselle, H; Rengan, R; Zeng, J; Saini, J; Wong, T

    2016-01-01

    Purpose: NSCLC patient RT is planned without consideration of spatial heterogeneity in lung function or tumor response, which may have contributed to failed uniform dose escalation in a randomized trial. The feasibility of functional lung avoidance and response-adaptive escalation (FLARE) RT to reduce dose to [ 99m Tc]MAA-SPECT/CT perfused lung while redistributing 74Gy within [ 18 F]FDG-PET/CT biological target volumes was assessed. Methods: Eight Stage IIB–IIIB NSCLC patients underwent FDG-PET/CT and MAA-SPECT/CT treatment planning scans. Perfused lung objectives were derived from scatter/collimator/attenuation-corrected MAA-SPECT uptake relative to ITV-subtracted lung to maintain <20Gy mean lung dose (MLD). Prescriptions included 60Gy to PTV and concomitant boost of 74Gy mean to biological target volumes (BTV=GTV+PET margin) scaled to each BTV voxel by relative FDG-PET SUV. Dose-painting-by-numbers prescriptions were integrated into commercial TPS via previously reported ROI discretization. Dose constraints for lung, heart, cord, and esophagus were defined. FLARE RT plans were optimized with VMAT, proton pencil beam scanning (PBS) with 3%-3mm robust optimization, and combination PBS (avoidance) plus VMAT (escalation). Dosimetric differences were evaluated by Friedman non-parametric paired test with multiple sampling correction. Results: PTV and normal tissue objectives were not violated in 24 FLARE RT plans. Population median of mean BTV dose was 73.7Gy (68.5–75.5Gy), mean FDG-PET peak dose was 89.7Gy (73.5–103Gy), MLD was 12.3Gy (7.5–19.6Gy), and perfused MLD was 4.8Gy (0.9–12.1Gy). VMAT achieved higher dose to the FDG-PET peak subvolume (p=0.01), while PBS delivered lower dose to lung (p<0.001). Voxelwise linear correlation between BTV dose and FDG-PET uptake was higher for VMAT (R=0.93) and PBS+VMAT (R=0.94) compared to PBS alone (R=0.89). Conclusion: FLARE RT is feasible with VMAT and PBS. A combination of PBS for functional lung avoidance and VMAT

  19. SU-D-202-01: Functional Lung Avoidance and Response-Adaptive Escalation (FLARE) RT: Feasibility of a Precision Radiation Oncology Strategy

    Energy Technology Data Exchange (ETDEWEB)

    Bowen, S; Lee, E; Miyaoka, R; Kinahan, P; Sandison, G; Vesselle, H; Rengan, R; Zeng, J [University of Washington, School of Medicine, Seattle, WA (United States); Saini, J; Wong, T [SCCA Proton Therapy Center, Seattle, WA (United States)

    2016-06-15

    Purpose: NSCLC patient RT is planned without consideration of spatial heterogeneity in lung function or tumor response, which may have contributed to failed uniform dose escalation in a randomized trial. The feasibility of functional lung avoidance and response-adaptive escalation (FLARE) RT to reduce dose to [{sup 99m}Tc]MAA-SPECT/CT perfused lung while redistributing 74Gy within [{sup 18}F]FDG-PET/CT biological target volumes was assessed. Methods: Eight Stage IIB–IIIB NSCLC patients underwent FDG-PET/CT and MAA-SPECT/CT treatment planning scans. Perfused lung objectives were derived from scatter/collimator/attenuation-corrected MAA-SPECT uptake relative to ITV-subtracted lung to maintain <20Gy mean lung dose (MLD). Prescriptions included 60Gy to PTV and concomitant boost of 74Gy mean to biological target volumes (BTV=GTV+PET margin) scaled to each BTV voxel by relative FDG-PET SUV. Dose-painting-by-numbers prescriptions were integrated into commercial TPS via previously reported ROI discretization. Dose constraints for lung, heart, cord, and esophagus were defined. FLARE RT plans were optimized with VMAT, proton pencil beam scanning (PBS) with 3%-3mm robust optimization, and combination PBS (avoidance) plus VMAT (escalation). Dosimetric differences were evaluated by Friedman non-parametric paired test with multiple sampling correction. Results: PTV and normal tissue objectives were not violated in 24 FLARE RT plans. Population median of mean BTV dose was 73.7Gy (68.5–75.5Gy), mean FDG-PET peak dose was 89.7Gy (73.5–103Gy), MLD was 12.3Gy (7.5–19.6Gy), and perfused MLD was 4.8Gy (0.9–12.1Gy). VMAT achieved higher dose to the FDG-PET peak subvolume (p=0.01), while PBS delivered lower dose to lung (p<0.001). Voxelwise linear correlation between BTV dose and FDG-PET uptake was higher for VMAT (R=0.93) and PBS+VMAT (R=0.94) compared to PBS alone (R=0.89). Conclusion: FLARE RT is feasible with VMAT and PBS. A combination of PBS for functional lung avoidance

  20. Reduced Radiation Dose with Model-based Iterative Reconstruction versus Standard Dose with Adaptive Statistical Iterative Reconstruction in Abdominal CT for Diagnosis of Acute Renal Colic.

    Science.gov (United States)

    Fontarensky, Mikael; Alfidja, Agaïcha; Perignon, Renan; Schoenig, Arnaud; Perrier, Christophe; Mulliez, Aurélien; Guy, Laurent; Boyer, Louis

    2015-07-01

    To evaluate the accuracy of reduced-dose abdominal computed tomographic (CT) imaging by using a new generation model-based iterative reconstruction (MBIR) to diagnose acute renal colic compared with a standard-dose abdominal CT with 50% adaptive statistical iterative reconstruction (ASIR). This institutional review board-approved prospective study included 118 patients with symptoms of acute renal colic who underwent the following two successive CT examinations: standard-dose ASIR 50% and reduced-dose MBIR. Two radiologists independently reviewed both CT examinations for presence or absence of renal calculi, differential diagnoses, and associated abnormalities. The imaging findings, radiation dose estimates, and image quality of the two CT reconstruction methods were compared. Concordance was evaluated by κ coefficient, and descriptive statistics and t test were used for statistical analysis. Intraobserver correlation was 100% for the diagnosis of renal calculi (κ = 1). Renal calculus (τ = 98.7%; κ = 0.97) and obstructive upper urinary tract disease (τ = 98.16%; κ = 0.95) were detected, and differential or alternative diagnosis was performed (τ = 98.87% κ = 0.95). MBIR allowed a dose reduction of 84% versus standard-dose ASIR 50% (mean volume CT dose index, 1.7 mGy ± 0.8 [standard deviation] vs 10.9 mGy ± 4.6; mean size-specific dose estimate, 2.2 mGy ± 0.7 vs 13.7 mGy ± 3.9; P < .001) without a conspicuous deterioration in image quality (reduced-dose MBIR vs ASIR 50% mean scores, 3.83 ± 0.49 vs 3.92 ± 0.27, respectively; P = .32) or increase in noise (reduced-dose MBIR vs ASIR 50% mean, respectively, 18.36 HU ± 2.53 vs 17.40 HU ± 3.42). Its main drawback remains the long time required for reconstruction (mean, 40 minutes). A reduced-dose protocol with MBIR allowed a dose reduction of 84% without increasing noise and without an conspicuous deterioration in image quality in patients suspected of having renal colic.

  1. A fast and efficient adaptive parallel ray tracing based model for thermally coupled surface radiation in casting and heat treatment processes

    Science.gov (United States)

    Fainberg, J.; Schaefer, W.

    2015-06-01

    A new algorithm for heat exchange between thermally coupled diffusely radiating interfaces is presented, which can be applied for closed and half open transparent radiating cavities. Interfaces between opaque and transparent materials are automatically detected and subdivided into elementary radiation surfaces named tiles. Contrary to the classical view factor method, the fixed unit sphere area subdivision oriented along the normal tile direction is projected onto the surrounding radiation mesh and not vice versa. Then, the total incident radiating flux of the receiver is approximated as a direct sum of radiation intensities of representative “senders” with the same weight factor. A hierarchical scheme for the space angle subdivision is selected in order to minimize the total memory and the computational demands during thermal calculations. Direct visibility is tested by means of a voxel-based ray tracing method accelerated by means of the anisotropic Chebyshev distance method, which reuses the computational grid as a Chebyshev one. The ray tracing algorithm is fully parallelized using MPI and takes advantage of the balanced distribution of all available tiles among all CPU's. This approach allows tracing of each particular ray without any communication. The algorithm has been implemented in a commercial casting process simulation software. The accuracy and computational performance of the new radiation model for heat treatment, investment and ingot casting applications is illustrated using industrial examples.

  2. Nonlinearity of radiation health effects.

    OpenAIRE

    Pollycove, M

    1998-01-01

    The prime concern of radiation protection policy since 1959 has been to protect DNA from damage. In 1994 the United Nations Scientific Community on the Effects of Atomic Radiation focused on biosystem response to radiation with its report Adaptive Responses to Radiation of Cells and Organisms. The 1995 National Council on Radiation Protection and Measurements report Principles and Application of Collective Dose in Radiation Protection states that because no human data provides direct support ...

  3. The principles of radiation protection

    International Nuclear Information System (INIS)

    2004-01-01

    The aim of radiation protection is to avoid or to reduce the risks linked to ionizing radiation. In order to reduce these risks, the radiation protection uses three great principles: justification, optimization and limitation of radiation doses. to apply these principles, the radiation protection has regulatory and technical means adapted to three different categories of people: public, patients and workers. The nuclear safety authority elaborates the regulation, and carries out monitoring of the reliable application of radiation protection system. (N.C.)

  4. A Hadron Radiation Installation and Verification Method

    NARCIS (Netherlands)

    Beekman, F.J.; Bom, V.R.

    2013-01-01

    A hadron radiation installation adapted to subject a target to irradiation by a hadron radiation beam, said installation comprising: - a target support configured to support, preferably immobilize, a target: - a hadron radiation apparatus adapted to emit a hadron radiation beam along a beam axis to

  5. Cytogenetic monitoring, radiosensitivity study and adaptive response of workers exposed to low level ionizing radiation; Monitorizacao citogenetica, estudo de radiossensibilidade e resposta adaptativa em profissionais expostos a baixos niveis de radiacao ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Peitl Junior, Paulo

    1996-07-01

    The objectives of the present study were: To determine the frequencies of chromosome aberrations in lymphocytes from individuals belonging to professionally exposed groups, under normal conditions; to determine the possible differences in radiosensitivity between the lymphocytes of technicians and controls after in vitro irradiation with gamma rays during the G{sub 1} phase of the cell cycle (radiosensitivity study), and to examine the influence of in vivo and in vitro pre-exposure to low doses of radiation on the frequency of chromosome aberrations induced in vitro by high doses (study of the adaptive response) in a group of technicians (T) compared to controls (C). (author)

  6. Radiation shelter

    International Nuclear Information System (INIS)

    Crookes, T.A.

    1982-01-01

    This patent application describes a shelter comprising a cavity for receiving life to be sheltered; a roof for covering at least a portion of said cavity, and at least one aqueous, protective barrier layer adapted to prevent transmission through said roof and into said cavity of at least a portion of radiation in a predetermined spectrum. The cavity walls may be impregnated with an oil suitable for dressing burns. (author)

  7. Adaptive-passive control of noise radiation of gear-box systems using a pair of shunted piezo-based rotating inertial actuators

    Science.gov (United States)

    Zhao, G.; Alujevic, N.; Depraetere, B.; Pinte, Gregory; Sas, P.

    2015-04-01

    In this paper, two Piezo-Based Rotating Inertial Actuators (PBRIAs) are considered for the suppression of the structureborne noise radiated from rotating machinery. Each inertial actuator comprises a piezoelectric stack element shunted with the Antoniou's gyrator circuit. This type of electrical circuit can be used to emulate a variable inductance. By varying the shunt inductance it is possible to realize two tuneable vibration neutralizers in order to suppress single frequency vibrations of a slowly rotating shaft. As a consequence, reductions in the sound radiated from the machine housing can be also achieved. First a theoretical study is performed using a simplified lumped parameter model of the system at hand. The simplified model consists of a rotating shaft and two perpendicularly mounted shunted PBRIAs. Secondly, the shunted PBRIA is tested on an experimental test bed comprising a rotating shaft mounted in a frame. The noise is radiated by a plate that is attached to the frame. The experimental results show that a reduction of 11 dB on the disturbance force transmitted from the rotating shaft through the bearing to the housing can be achieved. This also generates a reduction of 9 dB for the plate vibration and the radiated noise.

  8. Collimator with compensated filtration: clinical adaptation for recommendation 4f of the EU about the radiation protection in oral dental radiology

    International Nuclear Information System (INIS)

    Alcaraz, M.; Garcia-Vera, C.; Bravo, C. La; Morant, J. J.; Armedo, D. Y.; Canteras, M.

    2006-01-01

    Recent recommendations by the European Union (2004) for performing lateral cranial cephalometry (LCC) state that collimation should be maximized so that only those tissues necessary are irradiated when performing clinical diagnoses, although the fact that many manufacturers do not incorporate these elements in their equipment design has been recognised (recommendations 4f). Aim: the manufacture and utilization of a collimator with a pre-patient compensating filter for LLC which may be used in most extraoraldental radiology units, as well as determining the reduction in the dose of radiation absorbed by more sensitive tissues exposed to said clinical exploration. Making use of mannequins, phantom and craniums, we constructed a collimator with a compensating filter and established the necessary technical, dosimetric and quality specifications for its clinical use. Subsequently, we studied 16 patients referred for cephalometric study, determining the radiation dose (TLDs) in both the patients (crystalline lens, frontal lobe, parotid/submaxillary/thyroid glands and brain) and in the radiographic film, as well as in different parts of the collimator/filter. Al presented we are aiming for its clinical use by carrying out LCC in another 16 patients referred of orthodontic treatment but with the pre-a patient introduction of the tested collimator with the compensating filter as a substitute for the usual technique. The collimation reduced the field or radiation by some 40% and with that, so too the radiated tissues. The compensating filter reduced the dose in tissues by some 34.2. Our collimator has allowed the radiological image to be obtained with only one third the usual radiation dose. The dose reaching the film shies only between 17% less than in the usual technique and didn't alter its diagnostic capacity. A reduction of 61,6% of the dose administered to the patient is achieved by incorporating the collimator and filter to most radiological equipment without the need

  9. Radio-adaptive response

    International Nuclear Information System (INIS)

    Ikushima, T.

    1992-01-01

    An adaptive response to radiation stress was found as a suppressed induction of chromosomal damage including micronuclei and sister chromatid exchanges in cultured Chinese hamster V79 cells pre-exposed to very low doses of ionizing radiations. The mechanism underlying this novel chromosomal response, called 'radio-adaptive response (RAR)' has been studied progressively. The following results were obtained in recent experiments. 1. Low doses of β-rays from tritiated water (HTO) as well as tritium-thymidine can cause RAR. 2. Thermal neutrons, a high LET radiation, can not act as tritium β-rays or γ-rays. 3. The RAR expression is suppressed not only by the treatment with an inhibitor of protein synthesis but also by RNA synthesis inhibition. 4. Several proteins are newly synthesized concurrently with the RAR expression after the adapting doses, viewed by two-dimensional electrophoresis of cellular proteins. These results suggests that the RAR might be a cellular stress response to a signal produced preferentially by very low doses of low LET radiation under restricted conditions, accompany the inducible specific gene expression. (author)

  10. Development and adaptation of conduction and radiation heat-transfer computer codes for the CFTL. [Core Flow Test Loop; RODCON; HOTTEL

    Energy Technology Data Exchange (ETDEWEB)

    Conklin, J.C.

    1981-08-01

    RODCON and HOTTEL are two computational methods used to calculate thermal and radiation heat transfer for the Core Flow Test Loop (CFTL) analysis efforts. RODCON was developed at ORNL to calculate the internal temperature distribution of the fuel rod simulator (FRS) for the CFTL. RODCON solves the time-dependent heat transfer equation in two-dimensional (R angle) cylindrical coordinates at an axial plane with user-specified radial material zones and time- and position-variant surface conditions at the FRS periphery. Symmetry of the FRS periphery boundary conditions is not necessary. The governing elliptic, partial differential heat equation is cast into a fully implicit, finite-difference form by approximating the derivatives with a forward-differencing scheme with variable mesh spacing. The heat conduction path is circumferentially complete, and the potential mathematical problem at the rod center can be effectively ignored. HOTTEL is a revision of an algorithm developed by C.B. Baxi at the General Atomic Company (GAC) to be used in calculating radiation heat transfer in a rod bundle enclosed in a hexagonal duct. HOTTEL uses geometric view factors, surface emissivities, and surface areas to calculate the gray-body or composite view factors in an enclosure having multiple reflections in a nonparticipating medium.

  11. Volume and dosimetric changes and initial clinical experience of a two-step adaptive intensity modulated radiation therapy (IMRT) scheme for head and neck cancer

    International Nuclear Information System (INIS)

    Nishi, Tamaki; Nishimura, Yasumasa; Shibata, Toru; Tamura, Masaya; Nishigaito, Naohiro; Okumura, Masahiko

    2013-01-01

    Purpose: The aim of this study was to show the benefit of a two-step intensity modulated radiotherapy (IMRT) method by examining geometric and dosimetric changes. Material and Methods: Twenty patients with pharyngeal cancers treated with two-step IMRT combined with chemotherapy were included. Treatment-planning CT was done twice before IMRT (CT-1) and at the third or fourth week of IMRT for boost IMRT (CT-2). Transferred plans recalculated initial plan on CT-2 were compared with the initial plans on CT-1. Dose parameters were calculated for a total dose of 70 Gy for each plan. Results: The volumes of primary tumors and parotid glands on CT-2 regressed significantly. Parotid glands shifted medially an average of 4.2 mm on CT-2. The mean doses of the parotid glands in the initial and transferred plans were 25.2 Gy and 30.5 Gy, respectively. D 2 (dose to 2% of the volume) doses of the spinal cord were 37.1 Gy and 39.2 Gy per 70 Gy, respectively. Of 15 patients in whom xerostomia scores could be evaluated 1–2 years after IMRT, no patient complained of grade 2 or more xerostomia. Conclusions: This two-step IMRT method as an adaptive RT scheme could adapt to changes in body contour, target volumes and risk organs during IMRT

  12. Adaption of the radiation dose for computed tomography of the body - back-ground for the dose adaption programme OmnimAs; Straaldosreglering vid kroppsdatortomografi - bakgrund till dosregleringsprogrammet OmnimAs

    Energy Technology Data Exchange (ETDEWEB)

    Nyman, Ulf; Kristiansson, Mattias [Trelleborg Hospital (Sweden); Leitz, Wolfram [Swedish Radiation Protection Authority, Stockholm (Sweden); Paahlstorp, Per-Aake [Siemens Medical Solutions, Solna (Sweden)

    2004-11-01

    When performing computed tomography examinations the exposure factors are hardly ever adapted to the patient's size. One reason for that might be the lack of simple methods. In this report the computer programme OmnimAs is described which is calculating how the exposure factors should be varied together with the patient's perimeter (which easily can be measured with a measuring tape). The first approximation is to calculate the exposure values giving the same noise levels in the image irrespective the patient's size. A clinical evaluation has shown that this relationship has to be modified. One chapter is describing the physical background behind the programme. Results calculated with OmnimAs are in good agreement with a number of published studies. Clinical experiences are showing the usability of OmnimAs. Finally the correlation between several parameters and image quality/dose is discussed and how this correlation can be made use of for optimising CT-examinations.

  13. Third-generation dual-source CT of the neck using automated tube voltage adaptation in combination with advanced modeled iterative reconstruction: evaluation of image quality and radiation dose

    International Nuclear Information System (INIS)

    Scholtz, Jan-Erik; Wichmann, Julian L.; Huesers, Kristina; Albrecht, Moritz H.; Beeres, Martin; Bauer, Ralf W.; Vogl, Thomas J.; Bodelle, Boris

    2016-01-01

    To evaluate image quality and radiation dose in third-generation dual-source computed tomography (DSCT) of the neck using automated tube voltage adaptation (TVA) with advanced modelled iterative reconstruction (ADMIRE) algorithm. One hundred and sixteen patients were retrospectively evaluated. Group A (n = 59) was examined on second-generation DSCT with automated TVA and filtered back projection. Group B (n = 57) was examined on a third-generation DSCT with automated TVA and ADMIRE. Age, body diameter, attenuation of several anatomic structures, noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), radiation dose (CTDI vol ) and size-specific dose estimates (SSDE) were assessed. Diagnostic acceptability was rated by three readers. Age (p = 0.87) and body diameter (p = 0.075) did not differ significantly. Tube voltage in Group A was set automatically to 100 kV for all patients (n = 59), and to 70 kV (n = 2), 80 kV (n = 5), and 90 kV (n = 50) in Group B. Noise was reduced and CNR was increased significantly (p < 0.001). Diagnostic acceptability was rated high in both groups, with better ratings in Group B (p < 0.001). SSDE was reduced by 34 % in Group B (20.38 ± 1.63 mGy vs. 13.04 ± 1.50 mGy, p < 0.001). Combination of automated TVA and ADMIRE in neck CT using third-generation DSCT results in a substantial radiation dose reduction with low noise and increased CNR. (orig.)

  14. Manifestation pattern of early-late vaginal morbidity after definitive radiation (chemo)therapy and image-guided adaptive brachytherapy for locally advanced cervical cancer: an analysis from the EMBRACE study.

    Science.gov (United States)

    Kirchheiner, Kathrin; Nout, Remi A; Tanderup, Kari; Lindegaard, Jacob C; Westerveld, Henrike; Haie-Meder, Christine; Petrič, Primož; Mahantshetty, Umesh; Dörr, Wolfgang; Pötter, Richard

    2014-05-01

    Brachytherapy in the treatment of locally advanced cervical cancer has changed substantially because of the introduction of combined intracavitary/interstitial applicators and an adaptive target concept, which is the focus of the prospective, multi-institutional EMBRACE study (www.embracestudy.dk) on image-guided adaptive brachytherapy (IGABT). So far, little has been reported about the development of early to late vaginal morbidity in the frame of IGABT. Therefore, the aim of the present EMBRACE analysis was to evaluate the manifestation pattern of vaginal morbidity during the first 2 years of follow-up. In total, 588 patients with a median follow-up time of 15 months and information on vaginal morbidity were included. Morbidity was prospectively assessed at baseline, every 3 months during the first year, and every 6 months in the second year according to the Common Terminology Criteria for Adverse Events, version 3, regarding vaginal stenosis, dryness, mucositis, bleeding, fistula, and other symptoms. Crude incidence rates, actuarial probabilities, and prevalence rates were analyzed. At 2 years, the actuarial probability of severe vaginal morbidity (grade ≥3) was 3.6%. However, mild and moderate vaginal symptoms were still pronounced (grade ≥1, 89%; grade ≥2, 29%), of which the majority developed within 6 months. Stenosis was most frequently observed, followed by vaginal dryness. Vaginal bleeding and mucositis were mainly mild and infrequently reported. Severe vaginal morbidity within the first 2 years after definitive radiation (chemo)therapy including IGABT with intracavitary/interstitial techniques for locally advanced cervical cancer is limited and is significantly less than has been reported from earlier studies. Thus, the new adaptive target concept seems to be a safe treatment with regard to the vagina being an organ at risk. However, mild to moderate vaginal morbidity is still pronounced with currently applied IGABT, and it needs further attention

  15. Time course of immune system status in rats during adaptation to single and fractionated external low-level gamma-radiation

    International Nuclear Information System (INIS)

    Sambur, M.B.; Mel'nikov, O.F.; Timchenko, S.V.; Timchenko, M.D.

    1994-01-01

    The content of serum corticosterone so as immunological and nonspecific reactivity in rats exposed to single or fractionated gamma-radiation (0.35 Gy) were studied during 1 month. It has been revealed that corticosteron level, dynamics of absolute amount of leucocytes, lymphocytes, Rc-receptor-bearing cells in blood, relative content of FcR + -cells in bone marrow, spleen and peripheral lymph nodes of irradiated animals depend on the scheme of irradiation. Single irradiation didn't significantly influence natural and antibody-dependent killer cells activity and basal chemiluminescence level of polymorphonuclear cells, while the fractionated irradiation in equal dose induced considerable fluctuations of these parameters. The direction and intensity of the disturbance depend on the time after irradiation

  16. Assessment of radiation doses to the para-aortic, pelvic, and inguinal lymph nodes delivered by image-guided adaptive brachytherapy in locally advanced cervical cancer

    DEFF Research Database (Denmark)

    Mohamed, Sandy M I; Aagaard, Torben; Fokdal, Lars U

    2015-01-01

    .8-6.2 Gy equivalent total dose in 2-Gy fractions) to the pelvic LN (external iliac, internal iliac, obturator, and presacral) in optimized plans, whereas less-dose contribution to CI, para-aortic, and inguinal (mean D50% was 0.5-1.9 Gy equivalent total dose in 2-Gy fractions) was observed. Optimized plans......PURPOSE: This study evaluated the dose delivered to lymph nodes (LNs) by brachytherapy (BT) and the effect of BT image-guided optimization on the LN dose. METHODS AND MATERIALS: Twenty-five patients with locally advanced cervical cancer were retrospectively analyzed, 16 patients of them had LN...... involvement. The patients received whole pelvis intensity-modulated radiation therapy (45-50 Gy/25-30 fx) to whole pelvis and two fractions of MRI pulsed-dose-rate BT. The delineated LN groups were para-aortic, inguinal, common iliac (CI), external iliac, internal iliac, obturator, and presacral. For each LN...

  17. WE-AB-BRA-09: Sensitivity of Plan Re-Optimization to Errors in Deformable Image Registration in Online Adaptive Image-Guided Radiation Therapy

    International Nuclear Information System (INIS)

    McClain, B; Olsen, J; Green, O; Yang, D; Santanam, L; Olsen, L; Zhao, T; Rodriguez, V; Wooten, H; Mutic, S; Kashani, R; Victoria, J; Dempsey, J

    2015-01-01

    Purpose: Online adaptive therapy (ART) relies on auto-contouring using deformable image registration (DIR). DIR’s inherent uncertainties require user intervention and manual edits while the patient is on the table. We investigated the dosimetric impact of DIR errors on the quality of re-optimized plans, and used the findings to establish regions for focusing manual edits to where DIR errors can Result in clinically relevant dose differences. Methods: Our clinical implementation of online adaptive MR-IGRT involves using DIR to transfer contours from CT to daily MR, followed by a physicians’ edits. The plan is then re-optimized to meet the organs at risk (OARs) constraints. Re-optimized abdomen and pelvis plans generated based on physician edited OARs were selected as the baseline for evaluation. Plans were then re-optimized on auto-deformed contours with manual edits limited to pre-defined uniform rings (0 to 5cm) around the PTV. A 0cm ring indicates that the auto-deformed OARs were used without editing. The magnitude of the variations caused by the non-deterministic optimizer was quantified by repeat re-optimizations on the same geometry to determine the mean and standard deviation (STD). For each re-optimized plan, various volumetric parameters for the PTV, the OARs were extracted along with DVH and isodose evaluation. A plan was deemed acceptable if the variation from the baseline plan was within one STD. Results: Initial results show that for abdomen and pancreas cases, a minimum of 5cm margin around the PTV is required for contour corrections, while for pelvic and liver cases a 2–3 cm margin is sufficient. Conclusion: Focusing manual contour edits to regions of dosimetric relevance can reduce contouring time in the online ART process while maintaining a clinically comparable plan. Future work will further refine the contouring region by evaluating the path along the beams, dose gradients near the target and OAR dose metrics

  18. A Broadly Adaptive Array of Dose-Constraint Templates for Planning of Intensity-Modulated Radiation Therapy for Advanced T-Stage Nasopharyngeal Carcinoma

    International Nuclear Information System (INIS)

    Chau, R.M.-C.; Leung, S.-F.; Kam, M.K.-M.; Cheung, K.-Y.; Kwan, W.-H.; Yu, K.-H.; Chiu, K.-W.; Cheung, M.L.-M.; Chan, A.T.-C.

    2009-01-01

    Purpose: To develop and validate adaptive dose-constraint templates in intensity-modulated radiotherapy (IMRT) planning for advanced T-stage nasopharyngeal carcinoma (NPC). Method and Materials: Dose-volume histograms of clinically approved plans for 20 patients with advanced T-stage NPC were analyzed, and the pattern of distribution in relation to the degree of overlap between targets and organs at risk (OARs) was explored. An adaptive dose constraint template (ADCT) was developed based on the degree of overlap. Another set of 10 patients with advanced T-stage NPC was selected for validation. Results of the manual arm optimization protocol and the ADCT optimization protocol were compared with respect to dose optimization time, conformity indices, multiple-dose end points, tumor control probability, and normal tissue complication probability. Results: For the ADCT protocol, average time required to achieve an acceptable plan was 9 minutes, with one optimization compared with 94 minutes with more than two optimizations of the manual arm protocol. Target coverage was similar between the manual arm and ADCT plans. A more desirable dose distribution in the region of overlap between planning target volume and OARs was achieved in the ADCT plan. Dose end points of OARs were similar between the manual arm and ADCT plans. Conclusions: With the developed ADCT, IMRT treatment planning becomes more efficient and less dependent on the planner's experience on dose optimization. The developed ADCT is applicable to a wide range of advanced T-stage NPC treatment and has the potential to be applied in a broader context to IMRT planning for other cancer sites

  19. Hygienic significance of radiostability as measures of adaptive feasibilities

    International Nuclear Information System (INIS)

    Kudritskij, Yu.K.

    1987-01-01

    An attempt is made to substantiate hygienic significance of radiostability analysis as measures of adaptive feasibilities variation under the low dose ionizing radiation effect (IR). Examples of this substantiation are presented. Not only biological radiation effects but social adaptivity problems may be analysed. With more information adaptive feasibilities of human body to radiation factor are extended, its radiostability increases. Analysis of the state of adaptive feasibilities and their development estimation are vital problems of radiation hygiene, the basis for regulation and normalization of radiation factor

  20. Adaptive Motion Compensation in Radiotherapy

    CERN Document Server

    Murphy, Martin J

    2011-01-01

    External-beam radiotherapy has long been challenged by the simple fact that patients can (and do) move during the delivery of radiation. Recent advances in imaging and beam delivery technologies have made the solution--adapting delivery to natural movement--a practical reality. Adaptive Motion Compensation in Radiotherapy provides the first detailed treatment of online interventional techniques for motion compensation radiotherapy. This authoritative book discusses: Each of the contributing elements of a motion-adaptive system, including target detection and tracking, beam adaptation, and pati

  1. Determination of the adaptive response induced In vivo by gamma radiation and its relation with the sensibility to the damage induction in the DNA and with the repairing capacity

    International Nuclear Information System (INIS)

    Mendiola C, M.T.

    2002-01-01

    The kinetics of damage induction and repair at different doses as well as the adaptive response induced by gamma ray exposure were determined in murine leukocytes in vivo. The damage-repair kinetics were established after the exposure to 0.5, 1.0 or 2.0 Gy in a 137 Cs source. Peripheral blood samples were obtained from the tails of mice, the percentage of damaged cells and the DNA migration in each one were analyzed by the single cell gel electrophoresis (SCG) technique or comet assay. Results indicated that there was an induction of approximately 75% comets with the doses of 1.0 and 2.0 Gy, which was considerably reduced to 22% and 42% respectively during the first 15 minutes. This evidences the presence of a rapid repair process and suggests that leucocytes are genetically well prepared to repair this kind of damage. After 15 minutes, a second increase in the percentage of damaged cells that was proportional to dose occurred, which seems to represent the breaks produced during the repair of other kind of lesions. After that a second reduction was observed, reaching values near to the basal ones, except with the dose of 2.0 Gy. The kinetics obtained with the dose of 0.5 Gy was similar to that established with 1.0 Gy, but in this case the initial damage was 50 % lower. Besides, the adaptive response was observed after the exposure of the mice to an adaptive dose of 0.01 Gy and to a challenge dose of 1.0 Gy 60 minutes later. The pretreatment reduced the percentage of damaged cells caused by the challenge dose to one third approximately, and also diminished this parameter produced during the late repair process. This indicates that the early adaptive response is caused, instead of by an increment in repair, by the induction of a process that protects DNA from damage induction by radiation, i.e synthesis of substances that increase the scavenging of free radicals. (Author)

  2. Adaptive Lighting

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

    2015-01-01

    Adaptive Lighting Adaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities...... offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled in ways that meaningfully adapt according to people’s situations and design intentions. This book discusses...... differently into an architectural body. We also examine what might occur when light is dynamic and able to change colour, intensity and direction, and when it is adaptive and can be brought into interaction with its surroundings. In short, what happens to an architectural space when artificial lighting ceases...

  3. Advances in radiation therapy dosimetry

    OpenAIRE

    Paliwal, Bhudatt; Tewatia, Dinesh

    2009-01-01

    During the last decade, there has been an explosion of new radiation therapy planning and delivery tools. We went through a rapid transition from conventional three-dimensional (3D) conformal radiation therapy to intensity-modulated radiation therapy (IMRT) treatments, and additional new techniques for motion-adaptive radiation therapy are being introduced. These advances push the frontiers in our effort to provide better patient care; and with the addition of IMRT, temporal dimensions are ma...

  4. Can use of adaptive statistical iterative reconstruction reduce radiation dose in unenhanced head CT? An analysis of qualitative and quantitative image quality

    International Nuclear Information System (INIS)

    Østerås, Bjørn Helge; Heggen, Kristin Livelten; Pedersen, Hans Kristian; Andersen, Hilde Kjernlie; Martinsen, Anne Catrine T

    2016-01-01

    Iterative reconstruction can reduce image noise and thereby facilitate dose reduction. To evaluate qualitative and quantitative image quality for full dose and dose reduced head computed tomography (CT) protocols reconstructed using filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR). Fourteen patients undergoing follow-up head CT were included. All patients underwent full dose (FD) exam and subsequent 15% dose reduced (DR) exam, reconstructed using FBP and 30% ASIR. Qualitative image quality was assessed using visual grading characteristics. Quantitative image quality was assessed using ROI measurements in cerebrospinal fluid (CSF), white matter, peripheral and central gray matter. Additionally, quantitative image quality was measured in Catphan and vendor’s water phantom. There was no significant difference in qualitative image quality between FD FBP and DR ASIR. Comparing same scan FBP versus ASIR, a noise reduction of 28.6% in CSF and between −3.7 and 3.5% in brain parenchyma was observed. Comparing FD FBP versus DR ASIR, a noise reduction of 25.7% in CSF, and −7.5 and 6.3% in brain parenchyma was observed. Image contrast increased in ASIR reconstructions. Contrast-to-noise ratio was improved in DR ASIR compared to FD FBP. In phantoms, noise reduction was in the range of 3 to 28% with image content. There was no significant difference in qualitative image quality between full dose FBP and dose reduced ASIR. CNR improved in DR ASIR compared to FD FBP mostly due to increased contrast, not reduced noise. Therefore, we recommend using caution if reducing dose and applying ASIR to maintain image quality

  5. Can use of adaptive statistical iterative reconstruction reduce radiation dose in unenhanced head CT? An analysis of qualitative and quantitative image quality.

    Science.gov (United States)

    Østerås, Bjørn Helge; Heggen, Kristin Livelten; Pedersen, Hans Kristian; Andersen, Hilde Kjernlie; Martinsen, Anne Catrine T

    2016-08-01

    Iterative reconstruction can reduce image noise and thereby facilitate dose reduction. To evaluate qualitative and quantitative image quality for full dose and dose reduced head computed tomography (CT) protocols reconstructed using filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR). Fourteen patients undergoing follow-up head CT were included. All patients underwent full dose (FD) exam and subsequent 15% dose reduced (DR) exam, reconstructed using FBP and 30% ASIR. Qualitative image quality was assessed using visual grading characteristics. Quantitative image quality was assessed using ROI measurements in cerebrospinal fluid (CSF), white matter, peripheral and central gray matter. Additionally, quantitative image quality was measured in Catphan and vendor's water phantom. There was no significant difference in qualitative image quality between FD FBP and DR ASIR. Comparing same scan FBP versus ASIR, a noise reduction of 28.6% in CSF and between -3.7 and 3.5% in brain parenchyma was observed. Comparing FD FBP versus DR ASIR, a noise reduction of 25.7% in CSF, and -7.5 and 6.3% in brain parenchyma was observed. Image contrast increased in ASIR reconstructions. Contrast-to-noise ratio was improved in DR ASIR compared to FD FBP. In phantoms, noise reduction was in the range of 3 to 28% with image content. There was no significant difference in qualitative image quality between full dose FBP and dose reduced ASIR. CNR improved in DR ASIR compared to FD FBP mostly due to increased contrast, not reduced noise. Therefore, we recommend using caution if reducing dose and applying ASIR to maintain image quality.

  6. Adaptive Lighting

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

    2015-01-01

    Adaptive Lighting Adaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities...... offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled in ways that meaningfully adapt according to people’s situations and design intentions. This book discusses...... the investigations of lighting scenarios carried out in two test installations: White Cube and White Box. The test installations are discussed as large-scale experiential instruments. In these test installations we examine what could potentially occur when light using LED technology is integrated and distributed...

  7. MO-F-BRA-02: Evaluation of 4D CT to 4D Cone-Beam CT Deformable Image Registration for Lung Cancer Adaptive Radiation Therapy.

    Science.gov (United States)

    Balik, S; Hugo, G; Weiss, E; Jan, N; Roman, N; Sleeman, W; Fatyga, M; Christensen, G; Murphy, M; Lu, J; Keall, P; Williamson, J

    2012-06-01

    To evaluate two deformable image registration (DIR) algorithms for the purpose of contour mapping to support image guided adaptive radiotherapy (IGART) with 4D cone beam CT (4DCBCT). Eleven locally advanced non-small cell lung cancer (NSCLC) patients underwent one planning 4D fan- beam CT (4DFBCT) and seven weekly 4DCBCT scans. Gross tumor volume (GTV) and carina were delineated by a physician in all 4D images. For day to day registration, the end of inspiration 4DFBCT phase was deformably registered to the corresponding phase in each 4DCBCT image. For phase to phase registration, the end of inspiration phase from each 4D image was registered to end of expiration phase. The delineated contours were warped using the resulting transforms and compared to the manual contours through Dice similarity coefficient (DSC), false positive and false negative indices, and, for carina, target registration error (TRE). Two DIR algorithms were tested: 1) small deformation, inverse consistent linear elastic (SICLE) algorithm and 2) Insight Toolkit diffeomorphic demons (DEMONS). For day to day registrations, the mean DSC was 0.59 ± 0.16 after rigid registration, 0.72 ± 0.13 with SICLE and to 0.66 ± 0.18 with DEMONS. SICLE and DEMONS reduced TRE to 4.1 ± 2.1 mm and 5.8 ± 3.7 mm respectively, from 6.2 ± 3.5 mm; and reduced false positive index to 0.27 and 0.26 respectively from 0.46. Registration with the cone beam as the fixed image resulted in higher DSC than with the fan beam as fixed (p < 0.001). SICLE and DEMONS increased the DSC on average by 10.0% and 8.0% and reduced TRE by 2.8 mm and 2.9 mm respectively for phase to phase DIR. DIR achieved more congruent mapping of target structures to delineations than rigid registration alone, although DIR performance varied with algorithm and patient. This work was supported by National Cancer Institute Grant No. P01 CA 116602. © 2012 American Association of Physicists in Medicine.

  8. ADAPT Dataset

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced Diagnostics and Prognostics Testbed (ADAPT) Project Lead: Scott Poll Subject Fault diagnosis in electrical power systems Description The Advanced...

  9. Manifestation Pattern of Early-Late Vaginal Morbidity After Definitive Radiation (Chemo)Therapy and Image-Guided Adaptive Brachytherapy for Locally Advanced Cervical Cancer: An Analysis From the EMBRACE Study

    Energy Technology Data Exchange (ETDEWEB)

    Kirchheiner, Kathrin, E-mail: kathrin.kirchheiner@meduniwien.ac.at [Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/General Hospital of Vienna (Austria); Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna (Austria); Nout, Remi A. [Department of Clinical Oncology, Leiden University Medical Center (Netherlands); Tanderup, Kari; Lindegaard, Jacob C. [Department of Oncology, Aarhus University Hospital (Denmark); Westerveld, Henrike [Department of Radiotherapy, Academic Medical Centre, University of Amsterdam (Netherlands); Haie-Meder, Christine [Department of Radiotherapy, Gustave-Roussy, Villejuif (France); Petrič, Primož [Department of Radiotherapy, Institute of Oncology Ljubljana (Slovenia); Department of Radiotherapy, National Center for Cancer Care and Research, Doha (Qatar); Mahantshetty, Umesh [Department of Radiation Oncology, Tata Memorial Hospital, Mumbai (India); Dörr, Wolfgang; Pötter, Richard [Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/General Hospital of Vienna (Austria); Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna (Austria)

    2014-05-01

    Background and Purpose: Brachytherapy in the treatment of locally advanced cervical cancer has changed substantially because of the introduction of combined intracavitary/interstitial applicators and an adaptive target concept, which is the focus of the prospective, multi-institutional EMBRACE study ( (www.embracestudy.dk)) on image-guided adaptive brachytherapy (IGABT). So far, little has been reported about the development of early to late vaginal morbidity in the frame of IGABT. Therefore, the aim of the present EMBRACE analysis was to evaluate the manifestation pattern of vaginal morbidity during the first 2 years of follow-up. Methods and Materials: In total, 588 patients with a median follow-up time of 15 months and information on vaginal morbidity were included. Morbidity was prospectively assessed at baseline, every 3 months during the first year, and every 6 months in the second year according to the Common Terminology Criteria for Adverse Events, version 3, regarding vaginal stenosis, dryness, mucositis, bleeding, fistula, and other symptoms. Crude incidence rates, actuarial probabilities, and prevalence rates were analyzed. Results: At 2 years, the actuarial probability of severe vaginal morbidity (grade ≥3) was 3.6%. However, mild and moderate vaginal symptoms were still pronounced (grade ≥1, 89%; grade ≥2, 29%), of which the majority developed within 6 months. Stenosis was most frequently observed, followed by vaginal dryness. Vaginal bleeding and mucositis were mainly mild and infrequently reported. Conclusion: Severe vaginal morbidity within the first 2 years after definitive radiation (chemo)therapy including IGABT with intracavitary/interstitial techniques for locally advanced cervical cancer is limited and is significantly less than has been reported from earlier studies. Thus, the new adaptive target concept seems to be a safe treatment with regard to the vagina being an organ at risk. However, mild to moderate vaginal morbidity

  10. Adaptation Stories

    International Development Research Centre (IDRC) Digital Library (Canada)

    By Reg'

    formed a real foundation for endogenous, and, therefore, sustainable, strategies for adaptation to climate change. The stories reinforce what we already knew: that successful adaptation must come from the people who are living on the front lines, facing the many problems caused by climate change and climate variation.

  11. Radiation protection

    International Nuclear Information System (INIS)

    Koelzer, W.

    1975-01-01

    Physical and radiological terms, quantities, and units. Basic principles of radiation protection (ICRP, IAEA, EURATOM, FRG). Biological effects of ionizing radiation. Objectives of practical radiation protection. (HP) [de

  12. Radiation enteritis

    Science.gov (United States)

    Radiation enteropathy; Radiation-induced small bowel injury; Post-radiation enteritis ... Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells. The therapy ...

  13. Radiation biology

    International Nuclear Information System (INIS)

    Neumeister, K.

    1977-01-01

    This chapter is included in a textbook which is primarily intended for medical students. The following topics are dealt with: radiation effects on molecules; chemical and biochemical radiation effects; modification of radiation effects and radiosensitivity; radiation-induced pathomorphological and pathophysiological effects in organs and organ systems; radiation syndrome; radiation effects in embryos and fetuses; genetic radiation effects; carcinogenesis and leukemogenesis after irradiation; and radiation effects after intake of radionuclides

  14. Toothbrush Adaptations.

    Science.gov (United States)

    Exceptional Parent, 1987

    1987-01-01

    Suggestions are presented for helping disabled individuals learn to use or adapt toothbrushes for proper dental care. A directory lists dental health instructional materials available from various organizations. (CB)

  15. Ambiguous Adaptation

    DEFF Research Database (Denmark)

    Møller Larsen, Marcus; Lyngsie, Jacob

    2017-01-01

    intense relational mechanisms provide an effective means for contingency adaptation and therefore reduce the probability of premature termination. However, in situations where relationships are already governed by longer duration contracts, we argue that investments in relational mechanism create...

  16. Ambiguous Adaptation

    DEFF Research Database (Denmark)

    Møller Larsen, Marcus; Lyngsie, Jacob

    We investigate why some exchange relationships terminate prematurely. We argue that investments in informal governance structures induce premature termination in relationships already governed by formal contracts. The formalized adaptive behavior of formal governance structures and the flexible...... and reciprocal adaptation of informal governance structure create ambiguity in situations of contingencies, which, subsequently, increases the likelihood of premature relationship termination. Using a large sample of exchange relationships in the global service provider industry, we find support for a hypothesis...

  17. Strategic Adaptation

    DEFF Research Database (Denmark)

    Andersen, Torben Juul

    2015-01-01

    This article provides an overview of theoretical contributions that have influenced the discourse around strategic adaptation including contingency perspectives, strategic fit reasoning, decision structure, information processing, corporate entrepreneurship, and strategy process. The related...... concepts of strategic renewal, dynamic managerial capabilities, dynamic capabilities, and strategic response capabilities are discussed and contextualized against strategic responsiveness. The insights derived from this article are used to outline the contours of a dynamic process of strategic adaptation...

  18. Adaptive ethnography

    DEFF Research Database (Denmark)

    Berth, Mette

    2005-01-01

    This paper focuses on the use of an adaptive ethnography when studying such phenomena as young people's use of mobile media in a learning perspective. Mobile media such as PDAs and mobile phones have a number of affordances which make them potential tools for learning. However, before we begin...... formal and informal learning contexts. The paper also proposes several adaptive methodological techniques for studying young people's interaction with mobiles....

  19. Is adaptation. Truly an adaptation? Is adaptation. Truly an adaptation?

    Directory of Open Access Journals (Sweden)

    Thais Flores Nogueira Diniz

    2008-04-01

    Full Text Available The article begins by historicizing film adaptation from the arrival of cinema, pointing out the many theoretical approaches under which the process has been seen: from the concept of “the same story told in a different medium” to a comprehensible definition such as “the process through which works can be transformed, forming an intersection of textual surfaces, quotations, conflations and inversions of other texts”. To illustrate this new concept, the article discusses Spike Jonze’s film Adaptation. according to James Naremore’s proposal which considers the study of adaptation as part of a general theory of repetition, joined with the study of recycling, remaking, and every form of retelling. The film deals with the attempt by the scriptwriter Charles Kaufman, cast by Nicholas Cage, to adapt/translate a non-fictional book to the cinema, but ends up with a kind of film which is by no means what it intended to be: a film of action in the model of Hollywood productions. During the process of creation, Charles and his twin brother, Donald, undergo a series of adventures involving some real persons from the world of film, the author and the protagonist of the book, all of them turning into fictional characters in the film. In the film, adaptation then signifies something different from itstraditional meaning. The article begins by historicizing film adaptation from the arrival of cinema, pointing out the many theoretical approaches under which the process has been seen: from the concept of “the same story told in a different medium” to a comprehensible definition such as “the process through which works can be transformed, forming an intersection of textual surfaces, quotations, conflations and inversions of other texts”. To illustrate this new concept, the article discusses Spike Jonze’s film Adaptation. according to James Naremore’s proposal which considers the study of adaptation as part of a general theory of repetition

  20. Development of radiation alarm monitor

    International Nuclear Information System (INIS)

    Myung Jae Song; Myung Chan Lee; Jung Kwan Son

    1997-01-01

    The Radiation Alarm Monitor is developed domestically in order to protect radiation workers from over exposure. The Radiation Alarm Monitor with microprocessor installed can record the information of radiation field before and after accidents. It can also provide the data to analyze the accident and to set a counterplan. It features a wide detection range of radiation (I OmR/h - I OOR/h), radiation work and data storage, portability, high precision (5%) due to calibration, and adaptation of a powerful alarm system. In order to protect workers from over exposure, light and sound alarm had been designed to initiate when accident occurs such as an unexpected change of radiation field such as radiation rate and accumulated dosed between 90 min. before the alarm and 30 min. after the alarm. In addition, the Radiation Alarm Monitor interfaces with computer so that the accident can be analyzed. After the testing conditions in other countries for the Radiation Alarm Monitor were compared, the most stringent test, ANSI N42. 17-A, was selected. The performance testing was car-ried out under various conditions of temperature, humidity, vibration and electromagnetic wave hindrance by Korea Research Institute of Standards and Science (KRISS). As a result, the Radiation Alan-n Monitor passed all test. Also, for the Radiation Alarm Monitor, environmental adaptability tests under the environmental conditions of NPP sites had been performed. The Radiation Alan-n Monitor had been reviewed by radiation workers at NPPs and their opinions had been collected. Operating procedure will be written and distributed to every NPP sites. Radiation Alarm Monitor will be modified for use under the specific environmental conditions of each site. It will be distributed to NPP sites and will be used by radiation workers

  1. On adaptive radiation in gulls (tribe Larini)

    NARCIS (Netherlands)

    Tinbergen, N.

    1964-01-01

    In 1930 Professor Boschma, then Head of the Leiden Department of Zoology, generously allowed one of his undergraduates to spend an entire spring away from the laboratory, observing the love rituals of Terns. He even accepted the rather incoherent account this young man wrote of his observations as

  2. Strategic Adaptation

    DEFF Research Database (Denmark)

    Andersen, Torben Juul

    2015-01-01

    concepts of strategic renewal, dynamic managerial capabilities, dynamic capabilities, and strategic response capabilities are discussed and contextualized against strategic responsiveness. The insights derived from this article are used to outline the contours of a dynamic process of strategic adaptation......This article provides an overview of theoretical contributions that have influenced the discourse around strategic adaptation including contingency perspectives, strategic fit reasoning, decision structure, information processing, corporate entrepreneurship, and strategy process. The related....... This model incorporates elements of central strategizing, autonomous entrepreneurial behavior, interactive information processing, and open communication systems that enhance the organization's ability to observe exogenous changes and respond effectively to them....

  3. Adaptive test

    DEFF Research Database (Denmark)

    Kjeldsen, Lars Peter; Eriksen, Mette Rose

    2010-01-01

    Artikelen er en evaluering af de adaptive tests, som blev indført i folkeskolen. Artiklen sætter særligt fokus på evaluering i folkeskolen, herunder bidrager den med vejledning til evaluering, evalueringsværktøjer og fagspecifkt evalueringsmateriale.......Artikelen er en evaluering af de adaptive tests, som blev indført i folkeskolen. Artiklen sætter særligt fokus på evaluering i folkeskolen, herunder bidrager den med vejledning til evaluering, evalueringsværktøjer og fagspecifkt evalueringsmateriale....

  4. Is adaptation. Truly an adaptation?

    Directory of Open Access Journals (Sweden)

    Thais Flores Nogueira Diniz

    2006-04-01

    Full Text Available The article begins by historicizing film adaptation from the arrival of cinema, pointing out the many theoretical approaches under which the process has been seen: from the concept of “the same story told in a different medium” to a comprehensible definition such as “the process through which works can be transformed, forming an intersection of textual surfaces, quotations, conflations and inversions of other texts”. To illustrate this new concept, the article discusses Spike Jonze’s film Adaptation. according to James Naremore’s proposal which considers the study of adaptation as part of a general theory of repetition, joined with the study of recycling, remaking, and every form of retelling. The film deals with the attempt by the scriptwriter Charles Kaufman, cast by Nicholas Cage, to adapt/translate a non-fictional book to the cinema, but ends up with a kind of film which is by no means what it intended to be: a film of action in the model of Hollywood productions. During the process of creation, Charles and his twin brother, Donald, undergo a series of adventures involving some real persons from the world of film, the author and the protagonist of the book, all of them turning into fictional characters in the film. In the film, adaptation then signifies something different from itstraditional meaning.

  5. Adaptation is...

    International Development Research Centre (IDRC) Digital Library (Canada)

    IDRC

    vital sector is under threat. While it is far from the only development challenge facing local farmers, extreme variations in the climate of West Africa in the past several decades have dealt the region a bad hand. Drought and flood now follow each other in succession. Adaptation is... “The floods spoiled our harvests and we.

  6. Ambiguous Adaptation

    DEFF Research Database (Denmark)

    Møller Larsen, Marcus; Lyngsie, Jacob

    and reciprocal adaptation of informal governance structure create ambiguity in situations of contingencies, which, subsequently, increases the likelihood of premature relationship termination. Using a large sample of exchange relationships in the global service provider industry, we find support for a hypothesis...

  7. Adaptation Insights

    International Development Research Centre (IDRC) Digital Library (Canada)

    be given greater access to relevant information to help them adapt their farming practices and socio- economic strategies to climate change? To address this challenge, the project “InfoClim,” led by Senegal's. Ecological Monitoring Centre. (CSE) with support from the. CCAA program, aims at improving the access of farmers ...

  8. Adaptive Lighting

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Kongshaug, Jesper; Søndergaard, Karin

    2015-01-01

    differently into an architectural body. We also examine what might occur when light is dynamic and able to change colour, intensity and direction, and when it is adaptive and can be brought into interaction with its surroundings. In short, what happens to an architectural space when artificial lighting ceases...

  9. Studies on adaptive responses in Chinese hamster cells

    International Nuclear Information System (INIS)

    Michelin, S.C.; Perez, M.R. Del; Dubner, D.; Gisone, P.A.

    1997-01-01

    For many years the possibility has been considered of low doses of radiation inducing adaptive responses in cells and organisms against the mutagenic effects of radiation. Currently, a number of experimental data appraise the existence of an adaptive response that is characterized by a decrease of radiation induced genetic damages. The understanding of the molecular mechanism involved in this phenomenon permits to estimate the effects and risks of low dose exposure. In this work, preliminary results of studies on the induction of adaptive response in cells subjected to different doses of ionizing radiation are presented

  10. Radiation protection infrastructure

    International Nuclear Information System (INIS)

    1990-01-01

    A prerequisite for the safe use of ionizing radiation in a country is the availability of an adequate infrastructure to achieve the desired degree of protection. The extent of such an infrastructure, generally comprising regulatory mechanisms and technical capabilities for application and enforcement of regulations, has to be commensurate with the stage of technological development. The expanding application of ionizing radiation in medicine, industry and research calls for vigorous promotion of effective radiation protection efforts, not only to prevent any unsafe practices but also to assess correctly and provide authoritative information on the safety of adopted practices. Experience reveals that radiation protection practices vary considerably from one country to another. The regulatory structures and type of organization with regard to radiation protection are very different, depending on a number of factors such as the constitutional framework, the legal and administrative systems of the country concerned, the state of technical development, the status of application of radiation sources, the existence of research and associated institutions, and the technical skills and financial resources available. Radiation protection principles evolve with time as further experience is gained and as new research evidence becomes available. Regulation of radiation protection has to take account of such changes and adapt to changing conditions. Forty-eight papers from 29 Member States and two International Organizations were presented in nine scientific sessions. Topics included radiation protection regulation and licensing notification, registration, inspection and control programmes, education and training, the role of supporting institutions such as national laboratories and research institutes, the role of professional associations, the contribution of radiation protection services, and international activities. A concluding panel addressed development strategies to

  11. Radiation monitor

    International Nuclear Information System (INIS)

    Pao, C.T.; Green, W.K.

    1978-01-01

    A system for indicating radiation from a radioactive fluid such as a gas wherein simultaneous indications of the activity concentration of radioactivity of the gas, the radiation dose rate and average energy of the radiation are provided

  12. Radiation protection

    International Nuclear Information System (INIS)

    Ures Pantazi, M.

    1994-01-01

    This work define procedures and controls about ionizing radiations. Between some definitions it found the following topics: radiation dose, risk, biological effects, international radioprotection bodies, workers exposure, accidental exposure, emergencies and radiation protection

  13. Radiation dose rate measuring device

    International Nuclear Information System (INIS)

    Sorber, R.

    1987-01-01

    A portable device is described for in-field usage for measuring the dose rate of an ambient beta radiation field, comprising: a housing, substantially impervious to beta radiation, defining an ionization chamber and having an opening into the ionization chamber; beta radiation pervious electrically-conductive window means covering the opening and entrapping, within the ionization chamber, a quantity of gaseous molecules adapted to ionize upon impact with beta radiation particles; electrode means disposed within the ionization chamber and having a generally shallow concave surface terminating in a generally annular rim disposed at a substantially close spacing to the window means. It is configured to substantially conform to the window means to define a known beta radiation sensitive volume generally between the window means and the concave surface of the electrode means. The concave surface is effective to substantially fully expose the beta radiation sensitive volume to the radiation field over substantially the full ambient area faced by the window means

  14. Ionizing radiation

    International Nuclear Information System (INIS)

    Kruger, J.

    1989-01-01

    Ionizing radiation results in biological damage that differs from other hazardous substances and is highly dangerous to man. Ionizing radiation cannot be perceived by man's sense organs and the biological damage cannot be detected immediately afterwards (except in very high doses). Every human being is exposed to low doses of radiation. The structure of the atom; sources of ionizing radiation; radiation units; biological effects; norms for radiation protection; and the national control in South Africa are discussed. 1 fig., 5 refs

  15. Radiation dosimetry

    CERN Document Server

    Hine, Gerald J; Hine, Gerald J

    1956-01-01

    Radiation Dosimetry focuses on the advancements, processes, technologies, techniques, and principles involved in radiation dosimetry, including counters and calibration and standardization techniques. The selection first offers information on radiation units and the theory of ionization dosimetry and interaction of radiation with matter. Topics include quantities derivable from roentgens, determination of dose in roentgens, ionization dosimetry of high-energy photons and corpuscular radiations, and heavy charged particles. The text then examines the biological and medical effects of radiation,

  16. Phenomenon of adaptive response of cells in radiobiology

    International Nuclear Information System (INIS)

    Fillipovich, I.V.

    1991-01-01

    Consideration is given to various adaptive reactions to low-level radiation, their association with an absorbed dose, dose rate, radiation quality and time-interval between exposures, as well as with a cell cycle phase. Possible mechanisms of the adaptive response and the character and role of DNA damages, that can induce gene expression of the adaptive response, are discussed. The data on the influence of a preliminary long-term exposure to low-level radiation on the radiosensitivity of biological objects are analyzed with due regard for the adaptive cell response. It is concluded that the adaptive response of cells to ionizing radiation is a particular case of the phenomenon of cell adaptation of the effect of genotoxic factors of the environment

  17. Adaptation Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Huq, Saleemul

    2011-11-15

    Efforts to help the world's poor will face crises in coming decades as climate change radically alters conditions. Action Research for Community Adapation in Bangladesh (ARCAB) is an action-research programme on responding to climate change impacts through community-based adaptation. Set in Bangladesh at 20 sites that are vulnerable to floods, droughts, cyclones and sea level rise, ARCAB will follow impacts and adaptation as they evolve over half a century or more. National and international 'research partners', collaborating with ten NGO 'action partners' with global reach, seek knowledge and solutions applicable worldwide. After a year setting up ARCAB, we share lessons on the programme's design and move into our first research cycle.

  18. Adaptive sampler

    Science.gov (United States)

    Watson, B.L.; Aeby, I.

    1980-08-26

    An adaptive data compression device for compressing data is described. The device has a frequency content, including a plurality of digital filters for analyzing the content of the data over a plurality of frequency regions, a memory, and a control logic circuit for generating a variable rate memory clock corresponding to the analyzed frequency content of the data in the frequency region and for clocking the data into the memory in response to the variable rate memory clock.

  19. Adaptive positioner

    International Nuclear Information System (INIS)

    Labrador Pavon, I.

    1993-01-01

    This paper describes the circuits and programs in assembly language, developed to control the two DC motors that give mobility to a mechanical arm with two degrees of freedom. As a whole, the system is based in a adaptable regulator designed around a 8 bit microprocessor that, starting from a mode of regulation based in the successive approximation method, evolve to another mode through which, only one approximation is sufficient to get the right position of each motor. (Author) 6 refs

  20. Adaptable positioner

    International Nuclear Information System (INIS)

    Labrador Pavon, I.

    1993-01-01

    This paper describes the circuits and programs in assembly language, developed to control the two DC motors that give mobility to a mechanical arm with two degrees of freedom. As a whole, the system is based in a adaptable regulator designed around a 8 bit microprocessor that, starting from a mode of regulation based in the successive approximation method, evolve to another mode through which, only one approximation is sufficient to get the right position of each motor. (Author) 22 fig. 6 ref

  1. ADAPTATION EVALUATION

    Directory of Open Access Journals (Sweden)

    Björn PETERS, M.Sc.

    2001-01-01

    Full Text Available Twenty subjects with lower limb disabilities participated in a simulator study. The purpose of the study was to investigate how an Adaptive Cruise Control (ACC system together with two different hand controls for accelerator and brake influenced workload, comfort and driving behaviour and to further develop a method to evaluate vehicle adaptations for drivers with disabilities. The installed ACC system could maintain a constant speed selected and set by the driver and it also adapted speed in order to keep a safe distance to a leading vehicle. Furthermore, it included a stop-and-go function. Two common types of hand controls for accelerator and brake were used. The hand controls were different both with respect to function, single or dual levers, and position, on the steering column or between the front seats. The subjects were all experienced drivers of adapted cars equipped with hand controls. All subjects drove 100km at two occasions, with and without the ACC system available but with the same hand control. Subjective workload was found to be significantly lower and performance better for the ACC condition. The difference in speed variation between manual and ACC supported driving increased with the distance driven which seems to support the previous finding. The subjects thought they could control both speed and distance to leading vehicles better while the ACC was available. ACC driving did not influence reaction time, speed level, lateral position or variation in lateral position. Headway during car following situations was shorter for the ACC condition compared to manual driving. The ACC was well received, trusted and wanted. It was concluded that the ACC system substantially decreased workload, increased comfort and did not influence safety negatively. The only difference found between the two types of hand controls was that drivers using the dual lever system had less variation in lateral position. The applied evaluation method proved

  2. Radonotherapy and radiation hormesis

    International Nuclear Information System (INIS)

    Gusarov, I.I.; Dubovskoj, A.V.

    1999-01-01

    Based on the analysis of published data the concept is discussed concerning the fact that emission of Rn-222 and its daughter products containing in the atmospheric and accommodation air, at certain dose range is a natural stimulator for adaptive and defense forces of organism, improves viability and resistance to oncological diseases. Positive effect of Rn and its daughter products on vital activity of living organisms is considered to be the radiation hormesis manifestation. It is concluded that the medical effect of radon procedures is also the radiation hormesis evidence. From this viewpoint the hypothesis on mechanism of their biological and therapeutic effect is presented [ru

  3. Radiation protection

    CERN Multimedia

    CERN. Geneva

    2001-01-01

    This will be a simple explanation of the reasons why CERN has to be careful about radiation protections issues, a practical guide on how to recognize radiation dangers, the monitoring systems that make sure radiation levels are well tolerable norms, and a quick summary of what radiation levels mean in terms of personal risk.

  4. Adaptations to the perimeter environmental radiation monitoring network at the ININ (conceptual design of case); Adecuaciones a la red de monitoreo de radiacion ambiental perimetral del ININ (diseno conceptual de carcasa)

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez P, M. A.

    2016-07-01

    At present, equipment for the detection of gamma radiation existing in the environment is being developed to protect the population in the Mexico country. The Instituto Nacional de Investigaciones Nucleares (ININ) implemented the gamma radiation monitoring probe (GRMP), which is an instrument used to measure the ionizing radiation in the environment and this in turn communicates with the National Network for Radiological Environmental Monitoring, which detects in real time the gamma radiation. The probes are located in strategic points in the different States of the Mexican Republic and due to their exposure to different types of climate, cause different damages to the case of the GRMP. Due to this situation is that this work is focused on performing different tests to maintain the case in order to validate the problems encountered and investigate new improvements for optimal operation. (Author)

  5. Genomics and fish adaptation

    Directory of Open Access Journals (Sweden)

    Agostinho Antunes

    2015-12-01

    Full Text Available The completion of the human genome sequencing in 2003 opened a new perspective into the importance of whole genome sequencing projects, and currently multiple species are having their genomes completed sequenced, from simple organisms, such as bacteria, to more complex taxa, such as mammals. This voluminous sequencing data generated across multiple organisms provides also the framework to better understand the genetic makeup of such species and related ones, allowing to explore the genetic changes underlining the evolution of diverse phenotypic traits. Here, recent results from our group retrieved from comparative evolutionary genomic analyses of varied fish species will be considered to exemplify how gene novelty and gene enhancement by positive selection might have been determinant in the success of adaptive radiations into diverse habitats and lifestyles.

  6. Adaptive management

    DEFF Research Database (Denmark)

    Rist, Lucy; Campbell, Bruce Morgan; Frost, Peter

    2013-01-01

    a management framework, as well as of identified challenges and pathologies, are needed. Further discussion and systematic assessment of the approach is required, together with greater attention to its definition and description, enabling the assessment of new approaches to managing uncertainty, and AM itself.......Adaptive management (AM) emerged in the literature in the mid-1970s in response both to a realization of the extent of uncertainty involved in management, and a frustration with attempts to use modelling to integrate knowledge and make predictions. The term has since become increasingly widely used...... in scientific articles, policy documents and management plans, but both understanding and application of the concept is mixed. This paper reviews recent literature from conservation and natural resource management journals to assess diversity in how the term is used, highlight ambiguities and consider how...

  7. Adaptive response to ionizing radiation in normal human skin fibroblasts. Enhancement of DNA repair rate and modulation of gene expression. Reponse adaptative au rayonnement ionisant des fibroblastes de peau humaine. Augmentation de la vitesse de reparation de l'ADN et variation de l'expression des genes

    Energy Technology Data Exchange (ETDEWEB)

    Toledo, S.M. de; Mitchel, R.E.J. (Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.); Azzam, E. (Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs. Ottawa Univ., ON (Canada). Dept. of Biology); Raaphorst, G.P. (Ottawa Univ., ON (Canada). Dept. of Biology)

    Low doses and dose rates of ionizing radiation enhance the rate of DNA repair in human fibroblasts and protect the cells against radiation-induced micronucleus formation. Chronic exposures reduce the mRNA levels of the genes topoisomerase II and FACC-1 (Fanconi's anemia, group C). (authors). 11 refs., 1 tab., 2 figs.

  8. Radiation Therapy

    Science.gov (United States)

    ... radiation may be external, from special machines, or internal, from radioactive substances that a doctor places inside your body. The type of radiation therapy you receive depends on many factors, including The ...

  9. Radiation safety

    International Nuclear Information System (INIS)

    Woods, D.A.

    1982-01-01

    Sections include: dose units, dose limits, dose rate, potential hazards of ionizing radiations, control of internal and external radiation exposure, personal dosemeters, monitoring programs and transport of radioactive material (packaging and shielding)

  10. Radiation Therapy

    Science.gov (United States)

    ... kill any cancer cells that remain. Lifetime Dose Limits There is a limit to the amount of radiation an area of ... total dose of radiation more quickly or to limit damage to healthy cells. Different ways of delivering ...

  11. Radiation Emergencies

    Science.gov (United States)

    ... amounts of radiation and could be caused by Dirty bombs - a mix of explosives with radioactive powder Fallout from a nuclear bomb Accidental release from a nuclear reactor or a nuclear weapons plant A lot of radiation over a short ...

  12. Medical radiation

    Energy Technology Data Exchange (ETDEWEB)

    1992-06-01

    This leaflet in the At-a-Glance Series describes the medical use of X-rays, how X-rays help in diagnosis, radiation protection of the patient, staff protection, how radioactive materials in nuclear medicine examinations help in diagnosis and the use of radiation in radiotherapy. Magnetic resonance imaging, a diagnostic technique involving no ionizing radiation, is also briefly examined. The role of the NRPB in the medical use of radiation is outlined. (UK).

  13. Radiation watchdog

    International Nuclear Information System (INIS)

    Manning, R.

    1984-01-01

    Designated by WHO as a Collaborating Centre, the Radiation Emergency Assistance Center/Training Site (REAC/TS) in Oak Ridge, Tennessee provides assistance to all countries of the Americas in radiation accidents including human contamination or overexposure. It also conducts courses in radiation emergency response for health professionals from throughout the world

  14. Radiation Exposure

    Science.gov (United States)

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

  15. Radiation collimator for use with high energy radiation beams

    International Nuclear Information System (INIS)

    Malak, S.P.

    1978-01-01

    A collimator is described for use with a beam of radiation, and in particular, for use in controlling the cross-sectional size and shape of the radiation beam and intercepting undesired off-focus radiation in an x-ray apparatus. The collimator is positioned adjacent to the source of radiation and embodies a plurality longitudinally extending leaves pivotally mounted on and between two supports, the leaves move about their pivots to close overlapping relation to define a hollow cone. The cone defines an aperture at its narrow end which can be adjusted in size and shape by rotation of the two supports which are adaptable to being moved one relative to the other, to cause an expansion or contraction of the hollow cone and correspondingly an increase or decrease of the cross-sectional size and/or shape of the radiation beam passing through the aperture

  16. Are low radiation doses Dangerous?

    International Nuclear Information System (INIS)

    Garcia Lima, O.; Cornejo, N.

    1996-01-01

    In the last few years the answers to this questions has been affirmative as well as negative from a radiation protection point of view low doses of ionizing radiation potentially constitute an agent causing stochasting effects. A lineal relation without threshold is assumed between dose and probability of occurrence of these effects . Arguments against the danger of probability of occurrence of these effects. Arguments again the danger of low dose radiation are reflected in concepts such as Hormesis and adaptive response, which are phenomena that being studied at present

  17. Radiation imaging

    Energy Technology Data Exchange (ETDEWEB)

    Redmayne, I.

    1986-05-21

    A detector for the detection of radiation such as X-ray radiation comprises an array of scintillation elements embedded in a sheet of radiation absorbing material. The scintillation elements are monitored individually, for example by a corresponding array of photodiodes, to build up a picture of the incident radiation. The front face of the sheet and the inner walls of the bores may be coated with a reflective material. The detector finds particular application in weld radiography. The detector may be stepped relative to the radiation source, the signals produced by the rows of the detector as they pass a predetermined point being summed.

  18. Radiation imaging

    International Nuclear Information System (INIS)

    Redmayne, Ian.

    1986-01-01

    A detector for the detection of radiation such as X-ray radiation comprises an array of scintillation elements embedded in a sheet of radiation absorbing material. The scintillation elements are monitored individually, for example by a corresponding array of photodiodes, to build up a picture of the incident radiation. The front face of the sheet and the inner walls of the bores may be coated with a reflective material. The detector finds particular application in weld radiography. The detector may be stepped relative to the radiation source, the signals produced by the rows of the detector as they pass a predetermined point being summed. (author)

  19. Radiation dosimetry and radiation biophysics

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    Radiation dosimetry and radiation biophysics are two closely integrated programs whose joint purpose is to explore the connections between the primary physical events produced by radiation and their biological consequences in cellular systems. The radiation dosimetry program includes the theoretical description of primary events and their connection with the observable biological effects. This program also is concerned with the design and measurement of physical parameters used in theory or to support biological experiments. The radiation biophysics program tests and uses the theoretical developments for experimental design, and provides information for further theoretical development through experiments on cellular systems

  20. Radiation dosimetry and radiation biophysics

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Radiation dosimetry and radiation biophysics are two closely integrated programs whose joint purpose is to explore the connections between the primary physical events produced by radiation and their biological consequences in cellular systems. The radiation dosimetry program includes the theoretical description of primary events and their connection with the observable biological effects. This program also is concerned with design and measurement of those physical parameters used in the theory or to support biological experiments. The radiation biophysics program tests and makes use of the theoretical developments for experimental design. Also, this program provides information for further theoretical development through experiments on cellular systems

  1. Atoms, Radiation, and Radiation Protection

    CERN Document Server

    Turner, James E

    2007-01-01

    Atoms, Radiation, and Radiation Protection offers professionals and advanced students a comprehensive coverage of the major concepts that underlie the origins and transport of ionizing radiation in matter. Understanding atomic structure and the physical mechanisms of radiation interactions is the foundation on which much of the current practice of radiological health protection is based. The work covers the detection and measurement of radiation and the statistical interpretation of the data. The procedures that are used to protect man and the environment from the potential harmful effects of

  2. Manifestation pattern of early-late vaginal morbidity after definitive radiation (chemo)therapy and image-guided adaptive brachytherapy for locally advanced cervical cancer: an analysis from the EMBRACE study

    NARCIS (Netherlands)

    Kirchheiner, Kathrin; Nout, Remi A.; Tanderup, Kari; Lindegaard, Jacob C.; Westerveld, Henrike; Haie-Meder, Christine; Petrič, Primož; Mahantshetty, Umesh; Dörr, Wolfgang; Pötter, Richard

    2014-01-01

    Brachytherapy in the treatment of locally advanced cervical cancer has changed substantially because of the introduction of combined intracavitary/interstitial applicators and an adaptive target concept, which is the focus of the prospective, multi-institutional EMBRACE study (www.embracestudy.dk)

  3. Radiation protection in pediatric radiology.

    Science.gov (United States)

    Alzen, Gerhard; Benz-Bohm, Gabriele

    2011-06-01

    The German Federal Law on Radiation Control contains no special provisions for X-ray studies in children and adolescents, even though exposure to ionizing radiation must be kept especially low in young persons, because their tissues are highly radiosensitive. Children, who have many years left to live, are more likely than adults to develop radiation-induced cancer; also, as future parents, they are at risk for passing on radiation-induced genetic defects to the next generation. Whenever possible, radiological studies on children and adolescents should be of a type that does not involve ionizing radiation, such as ultrasonography or magnetic resonance imaging. Pediatric conventional X-rays and computerized tomography (CT) require special examining techniques and protocols that are adapted to the patient's age and to the indication for the study. We selectively review the literature on pediatric dose reduction and discuss our own investigations on the subject as well. The essential technical prerequisites for lowering the dose of ionizing radiation in conventional X-ray studies include the proper setting of tube voltage, the use of tube filters, suitable patient positioning and fixation, variable use of a scattered-radiation grid, and a modern storage-plate system. In CT studies, the use of age- and indication-adapted protocols can lower radiation exposure by as much as 95%. There are now many ways to lower the exposure of children and adolescents to ionizing radiation without sacrificing diagnostic reliability. The main factors in lowering exposure are proper attention to clinical indications, the use of special X-ray protocols, the use of alternative imaging studies without ionizing radiation wherever possible, and the expertise of the examiner.

  4. High Efficiency Lighting with Integrated Adaptive Control (HELIAC), Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed project is the continued development of the High Efficiency Lighting with Integrated Adaptive Control (HELIAC) system. Solar radiation is not a viable...

  5. Radiation carcinogenesis

    International Nuclear Information System (INIS)

    Fry, R.J.M.

    1976-01-01

    The risk of iatrogenic tumors with radiation therapy is so outweighed by the benefit of cure that estimates of risk have not been considered necessary. However, with the introduction of chemotherapy, combined therapy, and particle radiation therapy, the comparative risks should be examined. In the case of radiation, total dose, fractionation, dose rate, dose distribution, and radiation quality should be considered in the estimation of risk. The biological factors that must be considered include incidence of tumors, latent period, degree of malignancy, and multiplicity of tumors. The risk of radiation induction of tumors is influenced by the genotype, sex, and age of the patient, the tissues that will be exposed, and previous therapy. With chemotherapy the number of cells at risk is usually markedly higher than with radiation therapy. Clearly the problem of the estimation of comparative risks is complex. This paper presents the current views on the comparative risks and the importance of the various factors that influence the estimation of risk

  6. Radiation acoustics

    CERN Document Server

    Lyamshev, Leonid M

    2004-01-01

    Radiation acoustics is a developing field lying at the intersection of acoustics, high-energy physics, nuclear physics, and condensed matter physics. Radiation Acoustics is among the first books to address this promising field of study, and the first to collect all of the most significant results achieved since research in this area began in earnest in the 1970s.The book begins by reviewing the data on elementary particles, absorption of penetrating radiation in a substance, and the mechanisms of acoustic radiation excitation. The next seven chapters present a theoretical treatment of thermoradiation sound generation in condensed media under the action of modulated penetrating radiation and radiation pulses. The author explores particular features of the acoustic fields of moving thermoradiation sound sources, sound excitation by single high-energy particles, and the efficiency and optimal conditions of thermoradiation sound generation. Experimental results follow the theoretical discussions, and these clearl...

  7. Supporting Adaptive and Adaptable Hypermedia Presentation Semantics

    NARCIS (Netherlands)

    D.C.A. Bulterman (Dick); L. Rutledge (Lloyd); L. Hardman (Lynda); J.R. van Ossenbruggen (Jacco)

    1999-01-01

    textabstractHaving the content of a presentation adapt to the needs, resources and prior activities of a user can be an important benefit of electronic documents. While part of this adaptation is related to the encodings of individual data streams, much of the adaptation can/should be guided by the

  8. Hawking radiation

    Science.gov (United States)

    Parentani, Renaud; Spindel, Philippe

    2011-12-01

    Hawking radiation is the thermal radiation predicted to be spontaneously emitted by black holes. It arises from the steady conversion of quantum vacuum fluctuations into pairs of particles, one of which escaping at infinity while the other is trapped inside the black hole horizon. It is named after the physicist Stephen Hawking who derived its existence in 1974. This radiation reduces the mass of black holes and is therefore also known as black hole evaporation.

  9. Kinetics of the early adaptive response and adaptation threshold dose

    International Nuclear Information System (INIS)

    Mendiola C, M.T.; Morales R, P.

    2003-01-01

    The expression kinetics of the adaptive response (RA) in mouse leukocytes in vivo and the minimum dose of gamma radiation that induces it was determined. The mice were exposed 0.005 or 0.02 Gy of 137 Cs like adaptation and 1h later to the challenge dose (1.0 Gy), another group was only exposed at 1.0 Gy and the damage is evaluated in the DNA with the rehearsal it makes. The treatment with 0. 005 Gy didn't induce RA and 0. 02 Gy causes a similar effect to the one obtained with 0.01 Gy. The RA was show from an interval of 0.5 h being obtained the maximum expression with 5.0 h. The threshold dose to induce the RA is 0.01 Gy and in 5.0 h the biggest quantity in molecules is presented presumably that are related with the protection of the DNA. (Author)

  10. Radiation protection

    International Nuclear Information System (INIS)

    1989-01-01

    A NRPB leaflet in the 'At-a-Glance' series explains in a simple but scientifically accurate way what radiation is, the biological effects and the relative sensitivity of different parts of the human body. The leaflet then discusses radiation protection principles, radiation protection in the UK and finally the effectiveness of this radiation protection as judged by a breakdown of the total dose received by an average person in the UK, a heavy consumer of Cumbrian seafood, an average nuclear industry worker and an average person in Cornwall. (UK)

  11. GRAVITATIONAL RADIATION

    Directory of Open Access Journals (Sweden)

    Metin SALTIK

    1996-03-01

    Full Text Available According to classical electromagnetic theory, an accelerated charge or system of charges radiates electromagnetic waves. In a radio transmitter antenna charges are accelerated along the antenna and release electromagnetic waves, which is radiated at the velocity of light in the surrounding medium. All of the radio transmitters work on this principle today. In this study an analogy is established between the principles by which accelerated charge systems markes radiation and the accelerated mass system, and the systems cousing gravitational radiation are investigated.

  12. Radiation medicine

    International Nuclear Information System (INIS)

    1991-01-01

    This booklet has been produced by UKAEA and the Marie Curie Memorial Foundation to give some basic information about what radiation is and how it is used in day to day diagnosis and treatment. It will be of interest to people undergoing treatment, their relatives and friends, and anyone who wants to know more about this important area. After a brief historical introduction the booklet explains what radiation is, the natural and man-made sources of radiation, how it is produced and how X-rays are used in medical diagnosis and treatment. The radiation protection measures taken and safety standards followed are mentioned. (author)

  13. Adaptive speciation theory : A conceptual review

    NARCIS (Netherlands)

    Weissing, Franz J.; Edelaar, Pim; van Doorn, G. Sander

    Speciation-the origin of new species-is the source of the diversity of life. A theory of speciation is essential to link poorly understood macro-evolutionary processes, such as the origin of biodiversity and adaptive radiation, to well understood micro-evolutionary processes, such as allele

  14. Radiation and radiation protection; Strahlung und Strahlenschutz

    Energy Technology Data Exchange (ETDEWEB)

    Bartholomaeus, Melanie (comp.)

    2017-04-15

    The publication of the Bundesamt fuer Strahlenschutz covers the following issues: (i) Human beings in natural and artificial radiation fields; (ii) ionizing radiation: radioactivity and radiation, radiation exposure and doses; measurement of ionizing radiation, natural radiation sources, artificial radiation sources, ionizing radiation effects on human beings, applied radiation protection, radiation exposure of the German population, radiation doses in comparison; (iii) non-ionizing radiation; low-frequency electric and magnetic fields, high-frequency electromagnetic fields, optical radiation; (iiii) glossary, (iv) units and conversion.

  15. Concepts of radiation protection

    International Nuclear Information System (INIS)

    2013-01-01

    This seventh chapter presents the concepts and principles of safety and radiation protection, emergency situations; NORM and TENORM; radiation protection care; radiation protection plan; activities of the radiation protection service; practical rules of radiation protection and the radiation symbol

  16. Radiation myelopathy

    International Nuclear Information System (INIS)

    Berlit, P.

    1987-01-01

    After a review of the world literature, the case histories of 43 patients with radiation myelopathy are analyzed. In 1 patient there was a radiation injury of the medulla oblongata, in 2, cervical, in 28, thoracic, and in 12, lumbosacral. In the medulla oblongata lesion an alternans syndrome resulted. The patients with cervical and thoracic radiation myelopathies presented with a Brown-Sequard syndrome, a spinalis anterior syndrome or a transversal syndrome with pyramidal and spinothalamic tract involvement as the most prominent signs. For this group the term 'pyramidal-spinothalamic radiation myelopathy' is proposed. In lumbosacral radiation lesions a pure anterior horn syndrome may lead to spinothalamic tract involvement and the development of a cauda conus syndrome. The clinical presentation of these cases suggests that the location of the radiation lesion is most likely the region of the conus medullaris. The most frequent initial symptom was dysesthesia; the patients complained of burning pain or a feeling of coldness. Usually the neurological deficits were progressive, in pyramidal-spinothalamic radiation myelopathy over 12 months in average, in lumbosacral radiation lesions up to 10 years. The latent period between the finish of radiation therapy and the first neurological signs was 8 months (median) in cervical and thoracic myelopathy and 33 months in lumbosacral lesions. For the entire group of 43 patients there was an inverse relationship between the radiation dose (ret) and the latent period. A positive relation could be demonstrated between the age of patients at the time of radiation therapy and the latent period. Patients simultaneously receiving cytostatic drugs presented after a longer latent period than the remaining group. (orig./MG)

  17. Tolerance to gamma radiation in the marine heterotardigrade, Echiniscoides sigismundi

    DEFF Research Database (Denmark)

    Jönsson, K. Ingemar; Hygum, Thomas Lunde; Andersen, Kasper Nørgaard

    2016-01-01

    Tardigrades belong to the most radiation tolerant animals on Earth, as documented by a number of studies using both low-LET and high-LET ionizing radiation. Previous studies have focused on semi-terrestrial species, which are also very tolerant to desiccation. The predominant view on the reason...... for the high radiation tolerance among these semi-terrestrial species is that it relies on molecular mechanisms that evolved as adaptations for surviving dehydration. In this study we report the first study on radiation tolerance in a marine tardigrade, Echiniscoides sigismundi. Adult specimens in the hydrated...... that have high tolerance to both desiccation and radiation, supporting the hypothesis that radiation tolerance is a by-product of adaptive mechanisms to survive desiccation. More studies on radiation tolerance in tardigrade species adapted to permanently wet conditions, both marine and freshwater...

  18. BAKNET - Communication network for radiation monitoring devices

    International Nuclear Information System (INIS)

    Cohen, Y.; Wengrowicz, U.; Tirosh, D.; Barak, D.

    1997-01-01

    A system, based on a new concept of controlling and monitoring distributed radiation monitors, has been developed and approved at the NRCN. The system, named B AKNET Network , consists of a series of communication adapters connected to a main PC via an RS-485 communication network (see Fig. 1). The network's maximal length is 1200 meters and it enables connection of up to 128 adapters. The BAKNET adapters are designed to interface output signals of different types of stationary radiation monitors to a main PC. The BAKNET adapters' interface type includes: digital, analog, RS-232, and mixed output signals. This allows versatile interfacing of different stationary radiation monitors to the main computer. The connection to the main computer is via an RS-485 network, utilizing an identical communication protocol. The PC software, written in C ++ under MS-Windows, consists of two main programs. The first is the data collection program and the second is the Human Machine Interface (HMI). (authors)

  19. Radiation signatures

    International Nuclear Information System (INIS)

    McGlynn, S.P.; Varma, M.N.

    1992-01-01

    A new concept for modelling radiation risk is proposed. This concept is based on the proposal that the spectrum of molecular lesions, which we dub ''the radiation signature'', can be used to identify the quality of the causal radiation. If the proposal concerning radiation signatures can be established then, in principle, both prospective and retrospective risk determination can be assessed on an individual basis. A major goal of biophysical modelling is to relate physical events such as ionization, excitation, etc. to the production of radiation carcinogenesis. A description of the physical events is provided by track structure. The track structure is determined by radiation quality, and it can be considered to be the ''physical signature'' of the radiation. Unfortunately, the uniqueness characteristics of this signature are dissipated in biological systems in ∼10 -9 s. Nonetheless, it is our contention that this physical disturbance of the biological system eventuates later, at ∼10 0 s, in molecular lesion spectra which also characterize the causal radiation. (author)

  20. Radiation hematology

    International Nuclear Information System (INIS)

    Zherbin, E.A.; Chukhlovin, A.B.

    1989-01-01

    State-of-the-Art ofl radiation hematology and review of the problems now facing this brauch of radiobiology and nuclear medicine are presented. Distortion of division and maturation of hemopoiesis parent cells is considered as main factor of radiopathology for hematopoetic system. Problems of radiation injury and functional variation of hematopoetic microenvironment cell populations are discussed. 176 figs.; 23 figs.; 18 tabs

  1. Synchrotron radiation

    International Nuclear Information System (INIS)

    Nave, C.; Quinn, P.; Blake, R.J.

    1988-01-01

    The paper on Synchrotron Radiation contains the appendix to the Daresbury Annual Report 1987/88. The appendix is mainly devoted to the scientific progress reports on the work at the Synchrotron Radiation Source in 1987/8. The parameters of the Experimental Stations and the index to the Scientific Reports are also included in the appendix. (U.K.)

  2. Radiation oncology

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    The Radiation Oncology Division has had as its main objectives both to operate an academic training program and to carry out research on radiation therapy of cancer. Since fiscal year 1975, following a directive from ERDA, increased effort has been given to research. The research activities have been complemented by the training program, which has been oriented toward producing radiation oncologists, giving physicians short-term experience in radiation oncology, and teaching medical students about clinical cancer and its radiation therapy. The purpose of the research effort is to improve present modalities of radiation therapy of cancer. As in previous years, the Division has operated as the Radiation Oncology Program of the Department of Radiological Sciences of the University of Puerto Rico School of Medicine. It has provided radiation oncology support to patients at the University Hospital and to academic programs of the University of Puerto Rico Medical Sciences Campus. The patients, in turn, have provided the clinical basis for the educational and research projects of the Division. Funding has been primarily from PRNC (approx. 40%) and from National Cancer Institute grants channeled through the School of Medicine (approx. 60%). Special inter-institutional relationships with the San Juan Veterans Administration Hospital and the Metropolitan Hospital in San Juan have permitted inclusion of patients from these institutions in the Division's research projects. Medical physics and radiotherapy consultations have been provided to the Radiotherapy Department of the VA Hospital

  3. Background radiation

    International Nuclear Information System (INIS)

    Arnott, D.

    1985-01-01

    The effects of background radiation, whether natural or caused by man's activities, are discussed. The known biological effects of radiation in causing cancers or genetic mutations are explained. The statement that there is a threshold below which there is no risk is examined critically. (U.K.)

  4. Radiation guard apparatus

    International Nuclear Information System (INIS)

    Collica, C.; Epifano, L.; Farella, R.

    1976-01-01

    Radiation shielding apparatus for use in conjunction with a pad on a table. The apparatus comprises a set of units, each unit comprising a pair of joined substantially flat orthogonal flaps. The flaps are formed of a radiation shielding material and are adapted for removable placement under the pad whereby one flap contacts the table and the other flap extends vertically from an edge thereof. In a preferred embodiment of the invention the set consists of five units that provide protection around three sides of a rectangular table. In this embodiment, two of the units are identical and have asymmetrical trapezoidal flaps, and two others of the units are also identical, but have trapezoidal flaps which are of reversed orientation with respect to the first-mentioned two units. 6 claims, 4 drawing figures

  5. Radiation measuring instrument

    International Nuclear Information System (INIS)

    Genrich, V.

    1985-01-01

    A highly sensitive and compactly structured radiation measuring instrument for detecting ionizing radiation, in particular for measuring dose rates and contamination. The laminar structure of the associated counter tube, using only a few, simple plastic parts and a highly elastic counter wire, makes it possible to use the simplest manufacturing techniques. The service life of the counter tube construction, which is completely and permanently sealed and filled with gas, is expected to be more than 12 years. The described counter tube can be adapted in optimal fashion to the available space in a pocket instrument if it is used in combination with a specialized high-voltage generator which is low in interference voltage and with a pulse evaluation circuit having a means of compensating for interference voltage

  6. Adaptive antenna array algorithms and their impact on code division ...

    African Journals Online (AJOL)

    The adaptive antenna has an intelligent control unit, so the antenna canfollow the user, direct the radiation pattern towards the desired user, adapt to varying channel conditions and minimize the interference. Therefore there can be several users in the same channel in the same cell. The driving force of this intelligent ...

  7. Radiation sickness

    International Nuclear Information System (INIS)

    Endoh, Masaru; Ishida, Yusei; Saeki, Mitsuaki

    1983-01-01

    The frequency of radiation sickness in 1,060 patients treated at our Department was 12.8 percent. It was frequent in patients with brain cancer (12 percent), whole spine cancer (47 percent), uterus cancer (28 percent), lung cancer (22 percent) and esophagus cancer (12 percent). Radiation sickness following X-irradiation was studied in its relation to patient's age, size of radiation fields, dosis and white blood cell count. However, we could not find any definite clinical feature relevant to occurrence. There are many theories published concerning the mechanism of radiation sickness. Clinical experiences have shown that radiation sickness cannot be explained by one theory alone but by several theories such as those based on psychology, stress or histamine. (author)

  8. Radiation exposure

    International Nuclear Information System (INIS)

    Dalton, L.K.

    1991-01-01

    The book gives accounts of some social and environmental impacts of the developing radiation industries, including the experiences of affected communities and individuals. Its structure is based on a division which has been made between nuclear and non-nuclear radiation sources, because they create distinctly different problems for environmental protection and so for public health policy. The emissions from electronic and electrical installations - the non-nuclear radiations - are dealt with in Part I. Emissions from radioactive substances - the nuclear radiations - are dealt with in Part II. Part III is for readers who want more detailed information about scientific basis of radiation-related biological changes and their associated health effects. 75 refs., 9 tabs., 7 figs., ills

  9. Radiation carcinogenesis

    International Nuclear Information System (INIS)

    Adams, G.E.

    1987-01-01

    In this contribution about carcinogenesis induced by ionizing radiation some radiation dose-response relationships are discussed. Curves are shown of the relation between cell survival and resp. low and high LET radiation. The difference between both curves can be ascribed to endogenous repair mechanisms in the cell. The relation between single-gen mutation frequency and the surviving fractions of irradiated cells indicates that these repairing mechanisms are not error free. Some examples of reverse dose-response relationships are presented in which decreasing values of dose-rate (LET) correspond with increasing radiation induced cell transformation. Finally some molecular aspects of radiation carcinogenesis are discussed. (H.W.). 22 refs.; 4 figs

  10. Adaptation illustrations: Chapter 4

    Science.gov (United States)

    Maria Janowiak; Patricia Butler; Chris Swanston; Matt St. Pierre; Linda. Parker

    2012-01-01

    In this chapter, we demonstrate how the Adaptation Workbook (Chapter 3) can be used with the Adaptation Strategies and Approaches (Chapter 2) to develop adaptation tactics for two real-world management issues. The two illustrations in this chapter are intended to provide helpful tips to managers completing the Adaptation Workbook, as well as to show how the anticipated...

  11. The Evolving Theory of Evolutionary Radiations.

    Science.gov (United States)

    Simões, M; Breitkreuz, L; Alvarado, M; Baca, S; Cooper, J C; Heins, L; Herzog, K; Lieberman, B S

    2016-01-01

    Evolutionary radiations have intrigued biologists for more than 100 years, and our understanding of the patterns and processes associated with these radiations continues to grow and evolve. Recently it has been recognized that there are many different types of evolutionary radiation beyond the well-studied adaptive radiations. We focus here on multifarious types of evolutionary radiations, paying special attention to the abiotic factors that might trigger diversification in clades. We integrate concepts such as exaptation, species selection, coevolution, and the turnover-pulse hypothesis (TPH) into the theoretical framework of evolutionary radiations. We also discuss other phenomena that are related to, but distinct from, evolutionary radiations that have relevance for evolutionary biology. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Radiation therapy for cancer patients

    International Nuclear Information System (INIS)

    Mileikowsky, C.

    1987-01-01

    This patent describes an apparatus for irradiating a patient comprising: a source of a radiation beam directed along a radiation axis; means mounting the source for pivotal movement about a first horizontal axis which intersects the source, is stationary with respect to the apparatus, and extends in a direction substantially normal to the radiation axis, whereby the beam is capable of an angular scan in a vertical plane; table means adapted to support a patient to be irradiated; and suspension means mounted the table means for arcuate movement to any positions angularly spaced about the first horizontal axis and for pivoting movement about a second horizontal axis displacement from and substantially parallel to the first horizontal axis. The suspension means maintain the second horizontal axis in substantially intersecting relation to the radiation axis in each of the positions while maintaining a fixed angular position of the table means with respect to the environment

  13. Radiation therapy

    International Nuclear Information System (INIS)

    Bader, J.L.; Glatstein, E.

    1987-01-01

    The radiation oncologist encounters the critically ill immunosuppressed patient in four settings. First, the newly diagnosed cancer patient presents for initial evaluation and treatment, with immunosuppression from the cancer itself, malnutrition, concomitant infectious disease, prior drug or alcohol abuse or other medical problems. Second, the previously treated cancer patient presents with metastatic or recurrent primary cancer causing local symptoms. Immune dysfunction in this setting may be due to prior chemotherapy and/or radiation as well as any of the original factors. Third, the patient previously treated with radiation presents with a life-threatening problem possibly due to complications of prior therapy. In this setting, the radiation oncologist is asked to evaluate the clinical problem and to suggest whether radiation might be causing part or all of the problem and what can be done to treat these sequelae of radiation. Fourth, the patient with a benign diagnosis (not cancer) is seen with a problem potentially emeliorated by radiation (e.g., kidney transplant rejection, preparation for transplant, or intractable rheumatoid arthritis). This chapter reviews these four issues and presents clinical and radiobiologic principles on which recommendations for therapy are based

  14. Beneficial radiation?

    International Nuclear Information System (INIS)

    Roth, E.; Feinendegen, E.

    1996-01-01

    Ionizing radiation is harmful and may cause cancer, as is well known. However, again and again, low doses of ionizing radiation, under certain conditions, are said to have beneficial effects on human health and, in particular, may reduce the cancer rate. This effect, which is discussed controversially in the technical and scientific literature, is called 'hormesis'. Studies of possible positive effects of ionizing radiation are becoming increasingly more important in scientific research. The article is an attempt to show, by the model case of cancer, under what conditions such positive health effects can occur, at least in principle, and will also contain rough plausibility assessments of the existence of such conditions. Aspects not covered include other existing or presumed positive biological effects of ionizing radiation, such as acceleration of growth, or general increase in the life expectancy of organisms. Also genetic damage will not be discussed in greater detail, despite the existence of some parallels with cancer, both cases constituting lesions to the genetic material of the cells, in one case, germ cells and, in the case of cancer, somatic cells. Also, acute radiation effect will be excluded which occur only at high radiation doses and, as such, always cause damage which, in therapeutic application to cancer, may again be lifesaving. It should be emphasized that the article is limited to a greatly restricted range of biological effects of ionizing radiation which, consequently, are of limited value for overall assessment. (orig.) [de

  15. Radiation safety

    International Nuclear Information System (INIS)

    1996-04-01

    Most of the ionizing radiation that people are exposed to in day-to-day activities comes from natural, rather than manmade, sources. The health effects of radiation - both natural and artificial - are relatively well understood and can be effectively minimized through careful safety measures and practices. The IAEA, together with other international and expert organizations, is helping to promote and institute Basic Safety Standards on an international basis to ensure that radiation sources and radioactive materials are managed for both maximum safety and human benefit

  16. Radiation physics

    International Nuclear Information System (INIS)

    Nam, Sang Hui

    1991-02-01

    This book deals with radiation physics, which introduces atomic theory and an atomic nucleus of materials, conception of an atom and materials, wave and particle, X ray generation and character, a radioactive element and change law, nature of radioactivity, neutron rays, fission, alpha collapse and beta collage and a neutrino collapse of artificial radioactivity such as collapse of artificial nucleus and artificial radioactivity and radiative capture, interaction with materials like interaction between a charged particle and materials and interaction among X-ray, r-ray and materials, radiation of quantity and unit and a charged particle accelerator.

  17. Synchrotron radiation

    CERN Document Server

    Kunz, C

    1974-01-01

    The production of synchrotron radiation as a by-product of circular high-energy electron (positron) accelerators or storage rings is briefly discussed. A listing of existing or planned synchrotron radiation laboratories is included. The following properties are discussed: spectrum, collimation, polarization, and intensity; a short comparison with other sources (lasers and X-ray tubes) is also given. The remainder of the paper describes the experimental installations at the Deutsches Elektronen-Synchrotron (DESY) and DORIS storage rings, presents a few typical examples out of the fields of atomic, molecular, and solid-state spectroscopy, and finishes with an outlook on the use of synchrotron radiation in molecular biology. (21 refs).

  18. Radiation dosimeter

    International Nuclear Information System (INIS)

    Fox, R.J.

    1983-01-01

    A radiation detector readout circuit is provided which produces a radiation dose-rate readout from a detector even though the detector output may be highly energy dependent. A linear charge amplifier including an output charge pump circuit amplifies the charge signal pulses from the detector and pumps the charge into a charge storage capacitor. The discharge rate of the capacitor through a resistor is controlled to provide a time-dependent voltage which when integrated provides an output proportional to the dose-rate of radiation detected by the detector. This output may be converted to digital form for readout on a digital display

  19. Utilization of SRNL-developed radiation-resistant polymer in high radiation environments

    Energy Technology Data Exchange (ETDEWEB)

    Skibo, A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-09-27

    The radiation-resistant polymer developed by the Savannah River National Laboratory is adaptable for multiple applications to enhance polymer endurance and effectiveness in radiation environments. SRNL offers to collaborate with TEPCO in evaluation, testing, and utilization of SRNL’s radiation-resistant polymer in the D&D of the Fukushima Daiichi NPS. Refinement of the scope and associated costs will be conducted in consultation with TECPO.

  20. Radiating confidence

    International Nuclear Information System (INIS)

    Rush, P.

    1988-01-01

    Radiation monitoring systems for operators handling radioactive wastes are described. These include a personnel monitoring system which is suitable for small groups (ie as few as 50) of personnel. The use of microelectronics enable facilities such as automatic personal dose recording with three accumulative registers and automatic reporting of exceeded dose limits. At a controlled entrance the user is identified with a personal identification number. Exit is then also monitored. The use of pocket dosimeters increase the flexibility of this system. In another system a 'rotary man lock' only allows exit from the radiation controlled zone when satisfactory radiation checks have been made. The radiation and security checks available with this system are described. A 'sack monitor' for low level wastes contained in plastic bags is illustrated. (U.K.)

  1. Radiation curing

    International Nuclear Information System (INIS)

    Wendrinsky, J.

    1987-04-01

    In the beginning of the seventies the two types of radiation sources applied in industrial processes, electron radiation and UV, had been given rather optimistic forecasts. While UV could succeed in the field of panel and film coating, electron radiation curing seems to gain success in quite new fields of manufacturing. The listing of the suggested applications of radiation curing and a comparison of both advantages and disadvantages of this technology are followed by a number of case studies emphasizing the features of these processes and giving some examplary calculations. The data used for the calculations should provide an easy calculation of individual manufacturing costs if special production parameters, investment or energy costs are employed. (Author)

  2. Synchrotron Radiation

    International Nuclear Information System (INIS)

    Asfour, F.I

    2000-01-01

    Synchrotron light is produced by electron accelerators combined with storage rings. This light is generated over a wide spectral region; from infra-red (IR) through the visible and vacuum ultraviolet (VUV), and into the X-ray region. For relativistic electrons (moving nearly with the speed of light), most radiation is concentrated in a small cone with an opening angle of 1/gamma(some 0.1 to 1 milliradian),where gamma is the electron energy in units of rest energy (typically 10 3 -10 4 ). In synchrotron radiation sources (storage rings) highly relativistic electrons are stored to travel along a circular path for many hours. Radiation is caused by transverse acceleration due to magnetic forces(bending magnets). The radiation is emitted in pulses of 10-20 picosecond, separated by some 2 nanosecond or longer separation

  3. Infrared radiation

    International Nuclear Information System (INIS)

    Moss, C.E.; Ellis, R.J.; Murray, W.E.; Parr, W.H.

    1989-01-01

    All people are exposed to IR radiation from sunlight, artificial light and radiant heating. Exposures to IR are quantified by irradiance and radiant exposure to characterize biological effects on the skin and cornea. However, near-IR exposure to the retina requires knowledge of the radiance of the IR source. With most IR sources in everyday use the health risks are considered minimal; only in certain high radiant work environments are individuals exposed to excessive levels. The interaction of IR radiation with biological tissues is mainly thermal. IR radiation may augment the biological response to other agents. The major health hazards are thermal injury to the eye and skin, including corneal burns from far-IR, heat stress, and retinal and lenticular injury from near-IR radiation. 59 refs, 13 figs, 2 tabs

  4. Radiation shield

    International Nuclear Information System (INIS)

    Hosoya, Yasuaki

    1993-01-01

    In the present invention, the thickness of the radiation shields is minimized to save the quantity of shields thereby utilizing spaces in a facility effectively. That is, the radiation shields of the present invention comprise first and second shields forming stepwise gaps. They are disposed between a high dose region and a low dose region. The first and second shields have a feature in that the thickness thereof can be set to a size capable of shielding the gaps in accordance with the strength of the radiation source to be shielded. With such a constitution, the thickness of the shields of the radiation processing facility can be minimized. Accordingly, the quantity of the shields can be greatly saved. Spaces in the facility can be utilized effectively. (I.S.)

  5. Synchrotron radiation

    International Nuclear Information System (INIS)

    Helliwell, J.R.; Walker, R.P.

    1985-01-01

    A detailed account of the research work associated with the Synchrotron Radiation Source at Daresbury Laboratory, United Kingdom, in 1984/85, is presented in the Appendix to the Laboratory's Annual Report. (U.K.)

  6. Radiation sickness

    Science.gov (United States)

    ... GO About MedlinePlus Site Map FAQs Customer Support Health Topics Drugs & Supplements Videos & Tools Español You Are Here: Home → Medical Encyclopedia → Radiation sickness URL of this page: //medlineplus.gov/ency/article/ ...

  7. Radiation damage

    CERN Document Server

    Heijne, Erik H M; CERN. Geneva

    1998-01-01

    a) Radiation damage in organic materials. This series of lectures will give an overview of radiation effects on materials and components frequently used in accelerator engineering and experiments. Basic degradation phenomena will be presented for organic materials with comprehensive damage threshold doses for commonly used rubbers, thermoplastics, thermosets and composite materials. Some indications will be given for glass, scintillators and optical fibres. b) Radiation effects in semiconductor materials and devices. The major part of the time will be devoted to treat radiation effects in semiconductor sensors and the associated electronics, in particular displacement damage, interface and single event phenomena. Evaluation methods and practical aspects will be shown. Strategies will be developed for the survival of the materials under the expected environmental conditions of the LHC machine and detectors. I will describe profound revolution in our understanding of black holes and their relation to quantum me...

  8. Radiation sensors

    International Nuclear Information System (INIS)

    Wykes, J.S.; Adsley, I.

    1981-01-01

    Radiation detectors, suitable for use in industrial environments, eg coal mines are claimed. At least two scintillation crystals are mounted on a resilient support material, preferably silicone rubber. The sensors are both robust and compact. (U.K.)

  9. Adaptation of natural drosophila populations from radiocontaminated areas of Belarus

    International Nuclear Information System (INIS)

    Mosseh, I.B.; Glushkova, I.V.; Anoshenko, I.P.; Aksyutik, T.V.

    2005-01-01

    Genetic monitoring of natural drosophila populations from the area radiation contaminated due to Chernobyl accident (Vetka district of Gomel region) and from the control area (Byarehzinski National Reserve) had been conducted. Flies from radiation contaminated area were shown to be much more adapted to irradiation than insects from the control region. Then the population samples were kept under laboratory condition without irradiation for 8 generations. Adaptation of Vetka population to irradiation remained.. Besides the control population became also more resistant to ionizing radiation. Keeping of natural populations under laboratory or vivarium conditions is a strong stress (limited space, overpopulation, other than in nature temperature and light conditions), which increases mutation process and induces unspecific adaptation. These facts should be taken into account in studying dynamics of the mutation level during radionuclide removal in animals caught in radiation contaminated regions and placed in vivarium conditions. (authors)

  10. Radiation safety

    International Nuclear Information System (INIS)

    Goetz, B.B.; Murphy, C.H.

    1987-01-01

    In medicine, as in other fields of scientific endeavor, the development of advanced and specialized techniques has resulted in increased hazards for employees. However, by possessing both an appreciation of the proper use of factors that regulate radiation exposure around radiology equipment and a knowledge of the biologic effects of radiation, which can include possible genetic and somatic consequences, it is possible to maximize the usefulness of these valuable procedures while minimizing the risk to medical personnel involved with patient care

  11. Radiation Transport

    Energy Technology Data Exchange (ETDEWEB)

    Urbatsch, Todd James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-06-15

    We present an overview of radiation transport, covering terminology, blackbody raditation, opacities, Boltzmann transport theory, approximations to the transport equation. Next we introduce several transport methods. We present a section on Caseology, observing transport boundary layers. We briefly broach topics of software development, including verification and validation, and we close with a section on high energy-density experiments that highlight and support radiation transport.

  12. Synchrotron radiation

    International Nuclear Information System (INIS)

    Norman, D.; Walker, R.P.; Durham, P.J.; Ridley, P.A.

    1986-01-01

    The paper on synchrotron radiation is the appendix to the Daresbury (United Kingdom) annual report, 1985/86. The bulk of the volume is made up of the progress reports for the work carried out during the year under review using the Synchrotron Radiation Source (SRS) at Daresbury. The Appendix also contains: the scientific programmes at the the SRS, progress on beamlines, instrumentation and computing developments, and activities connected with accelerator development. (U.K.)

  13. Radiation protection

    International Nuclear Information System (INIS)

    Koelzer, W.

    1976-01-01

    The lecture is divided into five sections. The introduction deals with the physical and radiological terms, quantities and units. Then the basic principles of radiological protection are discussed. In the third section attention is paid to the biological effects of ionizing radiation. The fourth section deals with the objectives of practical radiological protection. Finally the emergency measures are discussed to be taken in radiation accidents. (HP) [de

  14. Synchrotron radiation

    International Nuclear Information System (INIS)

    Poole, M.W.; Lea, K.R.

    1982-01-01

    A report is given on the work involving the Synchrotron Radiation Division of the Daresbury Laboratory during the period January 1981 - March 1982. Development of the source, beamlines and experimental stations is described. Progress reports from individual investigators are presented which reveal the general diversity and interdisciplinary nature of the research which benefits from access to synchrotron radiation and the associated facilities. Information is given on the organisation of the Division and publications written by the staff are listed. (U.K.)

  15. Radiation Protection

    International Nuclear Information System (INIS)

    Loos, M.

    2001-01-01

    Major achievements of SCK-CEN's Radiation Protection Department in 2000 are described. The main areas for R and D of the department remain neutron dosimetry and neutron activation analysis, safeguards information handling and non-destructive assay techniques. Further activities include low-level radioactivity measurements in environmental and biological samples and radiation protection research. Finally, achievements in decision strategy research and social sciences in nuclear research are reported

  16. Some advances in radiation immunology

    International Nuclear Information System (INIS)

    Liu Shuzheng

    1985-01-01

    This paper is an overview of some of the recent advances in the study of radiation effects on immunity with special emphasis on the relation between radiation immunology and radiation carcinogenesis. The first part of the paper discusses the radiosensitivity of lymphocytes, emphasizing the heterogeneity of the lymphocyte population, the relative radiosensitivity of different lymphocyte subpopulations and their subsets, and the effect of the state of activation on lymphocyte radiosensitivity. The second part deals with the essentials of the theory of immunological surveillance, the specific and nonspecific components of anti-tumor immunity, and the effects of radiation on them. The last part of the paper is concerned with the phenomenon of radiation-induced augmentation of the immune response and the expression of radiation hormesis in the immune system with brief descriptions of some of the data from the author's laboratory. The need for a more sophisticated study of the possible hormetic effects of low level radiation on the immune system and other defense and adaptive functions of the body is stressed

  17. Optimization and radiation protection culture

    International Nuclear Information System (INIS)

    Jeon, In Young; Shin, Hyeong Ki; Lee, Chan Mi

    2013-01-01

    Safety culture or radiation protection culture is based in common on the term, 'culture'. Culture is defined as the learned, shared set of symbols and patterns of basic assumptions, which is invented, discovered, or developed by a given group as it learns to cope with its problem of external adaptation and internal integration. Safety culture generally refers to the attitude and behaviors affecting safety performance. The concept of 'Safety Culture' was introduced after the Chernobyl accident in 1986. For the accident, nuclear society reached the conclusion that the cause was the wrong management attitude of the NPP, that is, deficient 'Safety Culture'. Recently, 'Radiation Protection Culture' was introduced as the core concept of nuclear safety culture. There have been many efforts to establish definition and develop assessment tool for radiation protection culture in international level such as ICRP and IRPA as well as NRC. In the same context with the safety culture, radiation protection culture is defined as 'the core values and behaviors resulting from a collective commitment by leaders and individual's to emphasize safety over competing goals to ensure protection of people and the environment.' It is worthwhile to recognize that regulatory enforcement in establishing healthy radiation protection culture of operators should be minimized because culture is not in the domain of regulatory enforcement. However, as 'ALARA', the most important concept in radiation protection, may be successfully achieved only in well established radiation protection culture, the least regulatory intervention would be needed in promoting and nurturing radiation protection culture in licensee. In addition, the concept of radiation protection culture should be addressed in plant operational policy to achieve the goals of ALARA. The pre-condition of the successful radiation protection culture is a healthy organizational

  18. Expressing Adaptation Strategies Using Adaptation Patterns

    Science.gov (United States)

    Zemirline, N.; Bourda, Y.; Reynaud, C.

    2012-01-01

    Today, there is a real challenge to enable personalized access to information. Several systems have been proposed to address this challenge including Adaptive Hypermedia Systems (AHSs). However, the specification of adaptation strategies remains a difficult task for creators of such systems. In this paper, we consider the problem of the definition…

  19. Brain radiation - discharge

    Science.gov (United States)

    Radiation - brain - discharge; Cancer-brain radiation; Lymphoma - brain radiation; Leukemia - brain radiation ... Decadron) while you are getting radiation to the brain. It may make you hungrier, cause leg swelling ...

  20. Biological effects of low-dose ionizing radiation exposure

    International Nuclear Information System (INIS)

    Reinoehl-Kompa, Sabine; Baldauf, Daniela; Heller, Horst

    2009-01-01

    The report on the meeting of the Strahlenschutzkommission 2007 concerning biological effects of low-dose ionizing radiation exposure includes the following contributions: Adaptive response. The importance of DNA damage mechanisms for the biological efficiency of low-energy photons. Radiation effects in mammography: the relative biological radiation effects of low-energy photons. Radiation-induced cataracts. Carcinomas following prenatal radiation exposure. Intercellular apoptosis induction and low-dose irradiation: possible consequences for the oncogenesis control. Mechanistic models for the carcinogenesis with radiation-induced cell inactivation: application to all solid tumors in the Japanese atomic bomb survivors. Microarrays at low radiation doses. Mouse models for the analysis of biological effects of low-dose ionizing radiation. The bystander effect: observations, mechanisms and implications. Lung carcinoma risk of Majak workers - modeling of carcinogenesis and the bystander effect. Microbeam studies in radiation biology - an overview. Carcinogenesis models with radiation-induced genomic instability. Application to two epidemiological cohorts.

  1. Determination of the adaptive response induced In vivo by gamma radiation and its relation with the sensibility to the damage induction in the DNA and with the repairing capacity; Determinacion de la respuesta adaptativa inducida In vivo por radiacion gamma y su relacion con la sensibilidad a la induccion de dano en el ADN y con la capacidad de reparacion

    Energy Technology Data Exchange (ETDEWEB)

    Mendiola C, M.T

    2002-07-01

    The kinetics of damage induction and repair at different doses as well as the adaptive response induced by gamma ray exposure were determined in murine leukocytes in vivo. The damage-repair kinetics were established after the exposure to 0.5, 1.0 or 2.0 Gy in a {sup 137}Cs source. Peripheral blood samples were obtained from the tails of mice, the percentage of damaged cells and the DNA migration in each one were analyzed by the single cell gel electrophoresis (SCG) technique or comet assay. Results indicated that there was an induction of approximately 75% comets with the doses of 1.0 and 2.0 Gy, which was considerably reduced to 22% and 42% respectively during the first 15 minutes. This evidences the presence of a rapid repair process and suggests that leucocytes are genetically well prepared to repair this kind of damage. After 15 minutes, a second increase in the percentage of damaged cells that was proportional to dose occurred, which seems to represent the breaks produced during the repair of other kind of lesions. After that a second reduction was observed, reaching values near to the basal ones, except with the dose of 2.0 Gy. The kinetics obtained with the dose of 0.5 Gy was similar to that established with 1.0 Gy, but in this case the initial damage was 50 % lower. Besides, the adaptive response was observed after the exposure of the mice to an adaptive dose of 0.01 Gy and to a challenge dose of 1.0 Gy 60 minutes later. The pretreatment reduced the percentage of damaged cells caused by the challenge dose to one third approximately, and also diminished this parameter produced during the late repair process. This indicates that the early adaptive response is caused, instead of by an increment in repair, by the induction of a process that protects DNA from damage induction by radiation, i.e synthesis of substances that increase the scavenging of free radicals. (Author)

  2. Adaptive Modular Playware

    DEFF Research Database (Denmark)

    Lund, Henrik Hautop; Þorsteinsson, Arnar Tumi

    2011-01-01

    In this paper, we describe the concept of adaptive modular playware, where the playware adapts to the interaction of the individual user. We hypothesize that there are individual differences in user interaction capabilities and styles, and that adaptive playware may adapt to the individual user...... test set, the results are important as a proof of existence of differences and of the need for adaptation. The fact that there are individual differences makes the results significant for the development of games and interaction. It indicates that it is necessary to adapt the game and interaction......, if we desire to make the most appropriate game and interaction for the individual. Hence, we investigate adaptation as an important issue for playware. With simple playware games, we show that the adaptation will speed the game up and down to find the appropriate level that matches the reaction speed...

  3. Directional radiation detectors

    Science.gov (United States)

    Dowell, Jonathan L.

    2017-09-12

    Directional radiation detectors and systems, methods, and computer-readable media for using directional radiation detectors to locate a radiation source are provided herein. A directional radiation detector includes a radiation sensor. A radiation attenuator partially surrounds the radiation sensor and defines an aperture through which incident radiation is received by the radiation sensor. The aperture is positioned such that when incident radiation is received directly through the aperture and by the radiation sensor, a source of the incident radiation is located within a solid angle defined by the aperture. The radiation sensor senses at least one of alpha particles, beta particles, gamma particles, or neutrons.

  4. Radiation therapy of the uterine cancer

    International Nuclear Information System (INIS)

    Noguchi, Hiroshi

    1999-01-01

    Cervical and endometrial cancer of the uterus, and ovarian cancer are three major malignant diseases in gynecology in Japan. These diagnosis and therapy are almost established. In uterine cervical cancer, radiation therapy and surgery of these diseases are two main treatment methods, and both treatment results are almost the same. And radiation therapy is also used as postoperative treatment to patients with high risk factors. In endometrial cancer, surgery is main therapy. Radiation therapy is undergone only to medically inoperable cases preoperative radiation is widely carried out in Europe and America, but almost none in Japan. Postoperative irradiation is adapted to the cases with high risk factors. But recent advance of chemotherapy changes the importance of radiation therapy in such patients. I review the literatures of radiation therapy of uterine cervical cancer and of endometrial cancer. (author)

  5. Beneficial effects of radiation and regulatory policy

    Energy Technology Data Exchange (ETDEWEB)

    Jaworowski, Z. [Central Laboratory for Radiological Protection, Warsaw, (Poland)

    1997-09-01

    Adaptive and simulating effects of ionizing radiation occur at near natural doses. This disagrees with linear, no-threshold hypothesis on the dose/effect relationship, which is a basis of the current radiation protection. vast literature demonstrates that such effects, usually known as hormetic ones, occur at molecular, cellular and population levels, and often result in increased longevity and decreased cancer incidence. Exposure to lower than natural radiation causes deficiency symptoms in protozoa and bacteria. Hormetic effects suggest that the current radiation protection regulations may be too conservative. After the Chernobyl accident, adverse health effects and vast material losses were induced in the former USSR by practical implementation of the ICRP radiation protection recommendations. A revision of the current approach to managing the risks of ionizing radiation is needed for the public interest. (author). 67 refs., 8 tabs., 4 figs.

  6. Isotopes and radiations in agriculture

    International Nuclear Information System (INIS)

    Sawant, A.G.

    1998-01-01

    Some of the spectacular advances in agriculture in developing nations have stimulated wide interest both in basic as well as adaptive research and in harnessing all the tools that science can offer for progress of agriculture. The nuclear tools are relevant in this respect and also offer particular promise in some areas. Ionising radiations and isotopes have immense applications in agriculture. Both radioisotopes and stable isotopes are being used

  7. Tidal radiation

    International Nuclear Information System (INIS)

    Mashhoon, B.

    1977-01-01

    The general theory of tides is developed within the framework of Einstein's theory of gravitation. It is based on the concept of Fermi frame and the associated notion of tidal frame along an open curve in spacetime. Following the previous work of the author an approximate scheme for the evaluation of tidal gravitational radiation is presented which is valid for weak gravitational fields. The emission of gravitational radiation from a body in the field of a black hole is discussed, and for some cases of astrophysical interest estimates are given for the contributions of radiation due to center-of-mass motion, purely tidal deformation, and the interference between the center of mass and tidal motions

  8. Ionizing radiations

    International Nuclear Information System (INIS)

    2009-01-01

    After having recalled some fundamental notions and measurement units related to ionizing radiations, this document describes various aspects of natural and occupational exposures: exposure modes and sources, exposure levels, biological effects, health impacts. Then, it presents prevention principles aimed at, in an occupational context of use of radiation sources (nuclear industry excluded), reducing and managing these exposures: risk assessment, implementation of safety from the front end. Some practical cases illustrate the radiation protection approach. The legal and regulatory framework is presented: general notions, worker exposure, measures specific to some worker categories (pregnant and breast feeding women, young workers, temporary workers). A last part describes what is to be done in case of incident or accident (dissemination of radioactive substances from unsealed sources, anomaly occurring when using a generator or a sealed source, post-accident situation)

  9. Ionising radiation

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    The law covering ionising radiations in Belgium is summarised under the headings: the outline law of 19 March 1958; the General Regulation for the protection of the population and workers against the danger of ionising radiation (introduction; application; the control of classified establishments; organisation of general protection; importation, transit and distribution of radioactive substances; transport of radioactive substances; nuclear propulsion; ionising radiation in human or veterinary medicine; prohibitions and authorisations; exceptional measures; monitoring of the national territory and of the population as a whole; the approval of experts, organisations and doctors; monitoring; the public company for the management of radioactive waste and fissile materials); the law of 4 August 1955 concerning state security in the field of nuclear energy; civil responsibility; the Interministerial Commission on Nuclear Safety and State Security in the Nuclear Field; the non-proliferation of nuclear arms. (U.K.)

  10. Radiation sensor

    International Nuclear Information System (INIS)

    Brown, W.L.; Geronime, R.L.

    1977-01-01

    Radiation sensor and thermocouple, respectively, which can be used for reactor in-core instrumentation. The radiation sensor consists of an inconel conductor wire and rhodium emitter wire, the thermocouple of two intertwined alumel or chromel wires. Both are arranged in the center of a metal tube relative to which they are separated by an insulator made of SiO 2 fibers. This insulator is first introduced as a loose fabric between the radiation sensor and the thermocouple, respectively, and the metal tube and then compacted to a density of 35-73% of pure SiO 2 by drawing the tube. There is no need for soldering or welding. The insulation resistivity at room temperature ist between 10 14 and 10 15 ohms. (ORU) [de

  11. Radiofrequency radiation

    International Nuclear Information System (INIS)

    Elder, J.A.; Czerski, P.A.; Stuchly, M.A.; Mild, K.H.; Sheppard, A.R.

    1989-01-01

    High-level radiofrequency radiation is a source of thermal energy that carries all of the known implications of heating for biological systems, including burns, temporary and permanent changes in reproduction, cataracts, and death. In general, no changes in chromosomes, DNA or the reproductive potential of animals exposed to RF radiation have been reported in the absence of significant rises in temperature, though there are limited data on DNA and chromosomal changes at non-thermal levels. Human data are currently limited and do not provide adequate information about the relationship between prolonged low-level RF radiation exposure and increased mortality or morbidity, including cancer incidence. In epidemiological studies and clinical reports of RF effects in man, the problems of quantification are numerous and include uncertainties about ''dose'', health effects, latent periods, dose-response relationships, and interactions with other physical or chemical agents. 228 refs, 6 figs, 2 tabs

  12. Cherenkov radiation

    International Nuclear Information System (INIS)

    Hubert, P.

    1955-01-01

    When the radioactivity has been discovered, it was observed by researchers that different materials as mineral salts or solutions were emitting a weak light when submitted to radioactivity beams. At the beginning it has been thought that it was fluorescent light. In 1934, Cherenkov, a russian physicist, worked on the luminescence of uranyl salts solutions caused by gamma radiation and observed a very weak light was emitted by pure liquid. After further studies, he concluded that this phenomena was different from fluorescence. Since then, it has been called Cherenkov effect. This blue light emission is produced when charged particles are going through a transparent medium with an upper velocity than light velocity. This can happen only in medium with large refractive index as water or glass. It also presents its different properties discovered afterwards. The different applications of the Cherenkov radiation are discussed as counting techniques for radiation detectors or comic ray detectors. (M.P.)

  13. Adapting to climate change

    Science.gov (United States)

    Constance I. Millar; Christopher W. Swanston; David L. Peterson

    2014-01-01

    Federal agencies have led the development of adaptation principles and tools in forest ecosystems over the past decade. Successful adaptation efforts generally require organizations to: (1) develop science-management partnerships, (2) provide education on climate change science, (3) provide a toolkit of methods and processes for vulnerability assessment and adaptation...

  14. Adaptation to climate change

    NARCIS (Netherlands)

    Carmin, J.; Tierney, K.; Chu, E.; Hunter, L.M.; Roberts, J.T.; Shi, L.; Dunlap, R.E.; Brulle, R.J.

    2015-01-01

    Climate change adaptation involves major global and societal challenges such as finding adequate and equitable adaptation funding and integrating adaptation and development programs. Current funding is insufficient. Debates between the Global North and South center on how best to allocate the

  15. Radiation control

    International Nuclear Information System (INIS)

    Uchida, Akira

    1981-01-01

    This paper describes on how the condition of radiation level in the ring (storage ring) experimentation room changes corresponding to the operating stage of SOR-ring (synchrotron radiation storage ring), and does not describe on the present radiation control in the SOR facility. The operating stage of SOR is divided into the following five: (1) 307 MeV electron injection, (2) 307 MeV electron storage (used for SOR experiments), (3) energy increase from 307 to 380 MeV, (4) 380 MeV electron storage, (5) re-injection and completion of operation. Gamma and X ray levels are shown when electron beam is injected from the electron synchrotron to the SOR-ring. Two main causes of the high level are reported. Spatial dose rate in storing 307 MeV electrons in also illustrated. This is sufficiently lower than that at electron incidence. The measurement of radiation level at the time of energy increase from 307 to 380 MeV has just started. Since the radiation level in 380 MeV storage, measured at the points about 20 cm apart from the electron orbit, showed several mR/h, the level seems to be negligible at the points where experiments are carried out, 1 m away from the measurement points. The radiation level in electron reinjection and completion of operation may be large during a short period (a few Roentgen) like the time of energy increase. Therefore, the beam shall be re-injected or decreased after confirming that all experimenters have retreated into the predetermined place. (Wakatsuki, Y.)

  16. Radiation risks

    International Nuclear Information System (INIS)

    1991-01-01

    This report contains an evaluation of data available about the deleterious effects of exposure of people to ionising radiation, assuming that the total exposure is low (low dose) or that exposure to dose takes place gradually (low dose rate). It is a revision of the 1985 Health Council report on 'The scientific foundations for radiation protection policy based on the UNSCEAR-77, -82, and BEIR reports'. The report is also meant to be a reply to a request for advice made by the Minister of Welfare, Public Health and Culture in 1989. Scientific opinion on induction of cancer by radiation has clearly changed since 1988. This is a consequence of new publications of epidemiological studies among survivors of the atomic explosions of Hiroshima and Nagasaki. The Committee that has produced the present report has paid much attention to this development. Besides, in the request for advice just mentioned it is asked whether the margins of uncertainty which complicated the quantitative assessment of the radiation risk can be reduced. Consequently the Committee has dealt extensively with the potential errors and uncertainties in available data. Especially these 2 elements - a careful consideration of a recent shift in scientific opinion and a constant attention for the magnitude of potential uncertainties - have had a predominant influence on the content and design of this report. The Committee has tried to answer as fully as possible the complex question how to transform results of scientific research into a well-organised data set on which the government can base its radiation protection policy. The Committee had also compared its evaluation to the recent recommendations of the International Commission on Radiological Protection (ICRP) and the points of view of the Dutch policy directive 'Dealing with radiation risks'. (author). 111 refs.; 12 tabs

  17. Apparatus for minimizing radiation exposure and improving resolution in radiation imaging devices

    International Nuclear Information System (INIS)

    Ashe, J.B.; Williams, G.H.; Sypal, K.L.

    1978-01-01

    A collimator is disclosed for minimizing radiation exposure and improving resolution in radiation imaging devices. The collimator provides a penetrating beam of radiation from a source thereof, which beam is substantially non-diverging in at least one direction. In the preferred embodiment, the collimator comprises an elongated sandwich assembly of a plurality of layers of material exhibiting relatively high radiation attenuation characteristics, which attenuating layers are spaced apart and separated from one another by interleaved layers of material exhibiting relatively low radiation attenuation characteristics. The sandwich assembly is adapted for lengthwise disposition and orientation between a radiation source and a target or receiver such that the attenuating layers are parallel to the desired direction of the beam with the interleaved spacing layers providing direct paths for the radiation

  18. Radiation dermatitis

    Energy Technology Data Exchange (ETDEWEB)

    Shack, R.B.; Lynch, J.B.

    1987-04-01

    Even in this era of modern radiotherapy, injuries associated with the medical and industrial use of radiation devices will continue to pose a difficult problem for the reconstructive surgeon. It must be borne in mind that the single most serious hazard to surgery in irradiated tissue is the lodgement of bacteria in tissue rendered avascular by the radiation and the secondary necrosis from the infection itself. The basic principles of wound management must be augmented by thorough knowledge of the use of well-vascularized muscle and musculocutaneous flap to provide adequate, blood-rich, soft-tissue coverage.

  19. Radiation physics

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    The radiation physics program is directed toward understanding the basic mechanism by which charged particles lose energy in traversing matter, and presenting this information in a way meaningful to the study of radiation dosimetry and biological damage. Measurements of the absolute cross sections for the ejection of electrons from ionization by fast charged particles, measurements of optical fluorescence from liquid systems, preliminary analyses of electron emission cross sections for proton bombardment of carbon foils, and nonexponential decay of fluorescence in both polar and nonpolar solutions are covered

  20. Radiation toxicology

    International Nuclear Information System (INIS)

    Fry, R.J.M.; Storer, J.B.; Ullrich, R.L.

    1979-01-01

    Extensive studies on both human and experimental animal populations have provided information that allow radiation protection standards to be set with greater confidence than for most if not all other carcinogenic agents. Furthermore, both international and national advisory bodies are continually updating the risk estimates and the standards as new information is available. However, it is clear that models are needed that take into account the multistage nature of carcinogenesis. Studies in both ionizing and ultraviolet radiation carcinogenesis are more valuable to the general problem of elucidating the mechanisms involved in cancer than is indicated by the amount of work or support for this field of research

  1. Radiation toxicology

    International Nuclear Information System (INIS)

    Fry, R.J.M.; Storer, J.B.; Ullrich, R.L.

    1979-01-01

    The extensive studies on both human and experimental animal populations have provided information that allows radiation protection standards to be set with greater confidence than for most if not all other carcinogenic agents. Furthermore, both international and national advisory bodies are continually updating the risk estimates and the standards as new information is available. However, it is clear that we need models that take into account the multistage nature of carcinogenesis. Studies in both ionizing and ultraviolet radiation carcinogenesis are more valuable to the general problem of elucidating the mechanisms involved in cancer than is indicated by the amount of work or support for this field of research

  2. Radiations detection and nuclear instrumentation

    International Nuclear Information System (INIS)

    Abdallah, Lyoussi

    2010-01-01

    This book presents the physical principles, the performances, limits and domains of use of the main nuclear radiation detectors. The detection and characterization of a radioactive or nuclear material is possible using its characteristic, spontaneous or induced radiation emissions. Up to the end of the 1960's, the use of nuclear radiation detection and measurement methods remained limited. With the development of the nuclear industry, the main nations in concern have established control, monitoring and follow up procedures for nuclear materials and nuclear facilities as well. Nuclear detection, measurement and instrumentation started to develop and has been permanently improved and adapted thereafter. Today, nuclear instrumentation and measurement is a scientific, technical and technological subject on its own. This book presents, first, a recall of the radiation/matter interaction mechanisms with their basic physical principles. Basic and essential elements of statistics applied to radiation measurements are presented as well. Essential notions about electronic data acquisition and processing chains are explained. Then, some examples of application and use of radiation detectors are given, in particular in the domain of instrumentation and control systems for PWR type reactors. A series of exercises is proposed at the end of each chapter. (J.S.)

  3. Radiative MRI Coil Design Using Parasitic Scatterers

    DEFF Research Database (Denmark)

    Sanchez-Heredia, Juan D.; Avendal, Johan; Bibic, Adnan

    2018-01-01

    allows for antenna design techniques to be adapted to RF coil designs. This study proposes the use of parasitic scatterers to improve the performance of an existing 7T MRI coil called the single-sided adapted dipole (SSAD) antenna. The results reveal that scatterers arranged in a Yagi fashion can...... suitable for use in high density arrays. These findings show the potential of parasitic scatterers as an effective method to improve the performance of existing radiative MRI coils....

  4. Radiation enteropathy

    Energy Technology Data Exchange (ETDEWEB)

    Farthmann, E.H. (Chirurgische Universitaetsklinik, Freiburg im Breisgau (Germany)); Imdahl, A. (Chirurgische Universitaetsklinik, Freiburg im Breisgau (Germany)); Eggstein, S. (Chirurgische Universitaetsklinik, Freiburg im Breisgau (Germany))

    1994-08-01

    The pathogenesis, clinical picture, diagnosis and treatment of radiation damage to the gut are described. The progress of 90 patients operated on in the Chirurgische Universitaetsklinik Freiburg is retrospectively evaluated. Haemorrhage, vomiting, diarrhoea and, occasionally, perforation are the signs of acute radiation enteropathy, which appears weeks or months after radiotherapy. Expect for perforations, these can usually be treated conservatively. Chronic radiation enteropathy does not manifest itself until years after irradiation, with diarrhoea, obstruction and the development of fistulae. The acute ileus can often be relieved with decompression tubes. After localising the stenosis radiologically with a contrast medium, and improvement in the general condition, many cases require operative intervention. This usually consists of resection, the establishment of a bypass anastomosis or enterostomy. In 44% of the patients postoperative complications followed, with a mortality of 22%. The cause of the high complication rate is partly the poor general condition of the patient, and partly the radiation induced impairment in wound healing, which may lead to insufficiency of the anastomosis and the development of fistulae. (orig./MG)

  5. Radiation detectors

    International Nuclear Information System (INIS)

    2013-01-01

    This sixth chapter presents the operational principles of the radiation detectors; detection using photographic emulsions; thermoluminescent detectors; gas detectors; scintillation detectors; liquid scintillation detectors; detectors using semiconductor materials; calibration of detectors; Bragg-Gray theory; measurement chain and uncertainties associated to measurements

  6. Radiation processing

    International Nuclear Information System (INIS)

    Noriah Mod Ali

    2005-01-01

    This chapter covers the basic principle and application of radiation technology. The topic titled specific application discussed briefly the following subtopics: 1) Polymer modification - crosslinking, polymerisation, degradation, grafting; 2) Medical sterilisation; 3) Food irradiation; 4) Environmental protection - waste processing, pollutants treatment

  7. Radiation dosimetry

    International Nuclear Information System (INIS)

    Aymar A, J.; Medina G, H.

    1988-01-01

    Film is one of the most simple ways to detect radiation although for film as dosimeters a careful attention is required in many aspects, such as emulsion characteristics, film response capacity processing techniques and interpretation of the exposition. Surpassing these factors the film dosimeter is the most reliable

  8. Radiation enteropathy

    International Nuclear Information System (INIS)

    Farthmann, E.H.; Imdahl, A.; Eggstein, S.

    1994-01-01

    The pathogenesis, clinical picture, diagnosis and treatment of radiation damage to the gut are described. The progress of 90 patients operated on in the Chirurgische Universitaetsklinik Freiburg is retrospectively evaluated. Haemorrhage, vomiting, diarrhoea and, occasionally, perforation are the signs of acute radiation enteropathy, which appears weeks or months after radiotherapy. Expect for perforations, these can usually be treated conservatively. Chronic radiation enteropathy does not manifest itself until years after irradiation, with diarrhoea, obstruction and the development of fistulae. The acute ileus can often be relieved with decompression tubes. After localising the stenosis radiologically with a contrast medium, and improvement in the general condition, many cases require operative intervention. This usually consists of resection, the establishment of a bypass anastomosis or enterostomy. In 44% of the patients postoperative complications followed, with a mortality of 22%. The cause of the high complication rate is partly the poor general condition of the patient, and partly the radiation induced impairment in wound healing, which may lead to insufficiency of the anastomosis and the development of fistulae. (orig./MG) [de

  9. Radiation dosage

    International Nuclear Information System (INIS)

    Finston, Roland

    1986-01-01

    Radiation dosage at Bikini Atoll is the result of current soil contamination, a relic of the nuclear weapons testing program of some 30 years ago. The principal contaminants today and some of their physical properties are listed: cesium-137, strontium-90, plutonium -239, 240 and americium-241. Cobalt-60 contributes less than 1 to the dose and is not considered significant. A resident of the atoll would accumulate radiation dose (rem) in two ways -- by exposure to radiation emanating from the ground and vegetation, and by exposure to radiation released in the spontaneous decay of radionuclides that have entered his body during the ingestion of locally grown foods. The latter process would account for some 90% of the dose; cesium-137 would be responsible for 0 90% of it. Since BARC's method of estimating dosage differs in some respects from that employed by the Lawrence Livermore National Laboratory (LLNL), (Ref.1, LLNL 1982) we are presenting our method in detail. The differences have two sources. First, the numbers used by BARC for the daily ingestion of radionuclides via the diet are higher than LLNL's. Second, BARC's calculation of dose from radionuclide intake utilizes the ICRP system. The net result is that BARC doses are consistently higher than LLNL doses, and in this respect are more conservative

  10. Radiation accidents

    International Nuclear Information System (INIS)

    Saenger, E.L.

    1986-01-01

    It is essential that emergency physicians understand ways to manage patients contaminated by radioactive materials and/or exposed to external radiation sources. Contamination accidents require careful surveys to identify the metabolic pathway of the radionuclides to guide prognosis and treatment. The level of treatment required will depend on careful surveys and meticulous decontamination. There is no specific therapy for the acute radiation syndrome. Prophylactic antibodies are desirable. For severely exposed patients treatment is similar to the supportive care given to patients undergoing organ transplantation. For high-dose extremity injury, no methods have been developed to reverse the fibrosing endarteritis that eventually leads to tissue death so frequently found with this type of injury. Although the Three Mile Island episode of March 1979 created tremendous public concern, there were no radiation injuries. The contamination outside the reactor building and the release of radioiodine were negligible. The accidental fuel element meltdown at Chernobyl, USSR, resulted in many cases of acute radiation syndrome. More than 100,000 people were exposed to high levels of radioactive fallout. The general principles outlined here are applicable to accidents of that degree of severity

  11. Adaptive integral equation methods in transport theory

    International Nuclear Information System (INIS)

    Kelley, C.T.

    1992-01-01

    In this paper, an adaptive multilevel algorithm for integral equations is described that has been developed with the Chandrasekhar H equation and its generalizations in mind. The algorithm maintains good performance when the Frechet derivative of the nonlinear map is singular at the solution, as happens in radiative transfer with conservative scattering and in critical neutron transport. Numerical examples that demonstrate the algorithm's effectiveness are presented

  12. Introduction to radiation biology

    International Nuclear Information System (INIS)

    Gensicke, F.

    1977-01-01

    The textbook is written with special regard to radiation protection of man. It shall enable the reader to assess the potential radiation risks to living organisms and lead him to an insight into radiation protection measures. The following topics are covered: physical fundamentals of ionizing radiations; physical and chemical fundamentals of biological radiation effects; radiation effects on cells, organs, organ systems, and whole animal organisms focussing on mammals and man; modification of radiation effects; chemical radiation protection; therapy of radiation injuries; radionuclide kinetics; biological radiation effects in connection with radiation hazards and with the limitation of radiation exposure. It is intended for vocational education of medical personnel

  13. Adaptive Response- A Universal Phenomenon for Radiological Protection

    International Nuclear Information System (INIS)

    Streffer, C.

    2004-01-01

    Predominantly with cells in vitro but also with whole animals in vivo it bas been shown that small radiation doses like other stress factors can render cells or organisms to a stage of higher radioresistance. This has been demonstrated with chromosomal aberrations gene mutation, cell transformation and survival. However, it is necessary to keep the appropriate conditions in a very stringent way. This implies radiation dose ranges, time factors and others. The adaptive response is transient and keeps for about three cell cycles or two to three days for mammalian cells. Most studies have been performed with low LET radiation. From the few data with high LET radiation it can be concluded that the adaptive response is much less or does not occur at all. Cellular and molecular studies indicate that the DNA repair is most important for the induction of adaptive response although the understanding of the mechanisms is certainly incomplete. In vivo other biological phenomena like the immune system also play a significant role. A high individual variability exists with respect to the extent of the adaptive response. No adaptive response apparently occurs with cells from individuals with repair-and immune-deficiencies. Several experiments during the prenatal development indicate that there is no or only little adaptive response during wide developmental stages in utero. Therefore it must be concluded that the adaptive response has limitations and is not a universal principle. Due to these restrictions of the validity and strength of adaptive response it is doubtful whether adaptive response can generally be applied in the practice of radiological protection. (Author) 42 refs

  14. Thoughts on abatement and adaptation

    International Nuclear Information System (INIS)

    Revelle, R.R.

    1991-01-01

    A number of questions having to do with the themes of abatement and adaptation are discussed. Under the first rubric are questions of future concentrations of radiatively active trace gases, the linkage of these gases with greenhouse warming, and other environmental problems. Also examined in the abatement context are opportunities to reduce fossil fuel use and therefore the emission of greenhouse gases, and the likelihood that natural forest expansion may provide an opportunity to control the rate of carbon dioxide (CO2) accumulation in the atmosphere. Also discussed are the possible effects of greenhouse warming on agriculture in the United States and in the developing world. Finally, some suggestions are given on capturing and retaining interest in greenhouse warming on the part of the decision making public

  15. Evidence for beneficial low level radiation effects and radiation hormesis

    International Nuclear Information System (INIS)

    Feinendegen, L.E.

    2005-01-01

    Low doses in the mGy range cause a dual effect on cellular DNA. One effect concerns a relatively low probability of DNA damage per energy deposition event and it increases proportional with dose, with possible bystander effects operating. This damage at background radiation exposure is orders of magnitudes lower than that from endogenous sources, such as ROS. The other effect at comparable doses brings an easily obeservable adaptive protection against DNA damage from any, mainly endogenous sources, depending on cell type, species, and metabolism. Protective responses express adaptive responses to metabolic perturbations and also mimic oxygen stress responses. Adaptive protection operates in terms of DNA damage prevention and repair, and of immune stimulation. It develops with a delay of hours, may last for days to months, and increasingly disappears at doses beyond about 100 to 200 mGy. Radiation-induced apoptosis and terminal cell differentiation occurs also at higher doses and adds to protection by reducing genomic instability and the number of mutated cells in tissues. At low doses, damage reduction by adaptive protection against damage from endogenous sources predictably outweighs radiogenic damage induction. The analysis of the consequences of the particular low-dose scenario shows that the linear-no-threshold (LNT) hypothesis for cancer risk is scientifically unfounded and appears to be invalid in favor of a threshold or hormesis. This is consistent with data both from animal studies and human epidemiological observations on low-dose induced cancer. The LNT hypothesis should be abandoned and be replaced by a hypothesis that is scientifically justified. The appropriate model should include terms for both linear and non-linear response probabilities. Maintaining the LNT-hypothesis as basis for radiation protection causes unressonable fear and expenses. (author)

  16. Risk Factors: Radiation

    Science.gov (United States)

    Radiation of certain wavelengths, called ionizing radiation, has enough energy to damage DNA and cause cancer. Ionizing radiation includes radon, x-rays, gamma rays, and other forms of high-energy radiation.

  17. Radiation Therapy for Cancer

    Science.gov (United States)

    ... material placed in the body near cancer cells ( internal radiation therapy , also called brachytherapy ). Systemic radiation therapy uses radioactive ... material placed in the body near cancer cells (internal radiation therapy, more commonly called brachytherapy). Systemic radiation therapy uses ...

  18. Chest radiation - discharge

    Science.gov (United States)

    Radiation - chest - discharge; Cancer - chest radiation; Lymphoma - chest radiation ... When you have radiation treatment for cancer, your body goes through changes. About 2 weeks after your first treatment: It may be hard ...

  19. Radiation effects

    International Nuclear Information System (INIS)

    Collings, E.W.

    1986-01-01

    An important cause of deterioration in superconducting magnets intended for high-energy physics and fusion-reactor applications is radiation damage. The present chapter deals chiefly with the effects of electron, proton, gamma and neutron irradiation on the properties of stabilized Ti-Nb-base composite superconductors. The authors examine the particle-accelerator environment, electron irradiation of Ti-Nb superconductor, proton irradiation of Ti-Nb superconductor and its stabilizer, and deuteron irradiation of Ti-Nb superconductor. A section discussing the fusion reactor environment in general is presented, and the two principal classes of fusion reactor based on the magnetic-confinement concept, namely the tokamak and the mirrormachine are examined. Also discussed is neutron irradiation of Cu/TiNb composite superconductors and critical current density of neutronirradiated Ti-Nb. Finally, radiation damage to stabilizer and insulating materials is described

  20. Realtime radiation exposure monitor and control apparatus

    International Nuclear Information System (INIS)

    Cowart, R.W.

    1981-01-01

    This patent application relates to an apparatus and methods used to obtain image information from modulation of a uniform flux. An exposure measuring apparatus is disclosed which comprises a multilayered detector structure having an external circuit connected to a transparent insulating layer and to a conductive plate a radiation source adapted to irradiate the detector structure with radiation capable of producing electron-hole pairs in a photoconductive layer of the detector wherein the flow of current within the external circuit is measured when the detector is irradiated by the radiation source. (author)

  1. Radiation detector

    International Nuclear Information System (INIS)

    Gillies, W.

    1980-01-01

    The radiation detector for measuring e.g. a neutron flux consists of a central emitter, an insulating shell arranged around it, and a tube-shaped collector enclosing both. The emitter itself is composed of a great number of stranded, spiral wires of small diameter giving a defined flexibility to the detector. For emitter material Pt, Rh, V, Co, Ce, Os or Ta may be used. (DG) [de

  2. Radiation accidents

    International Nuclear Information System (INIS)

    Poplavskij, K.K.; Smorodintseva, G.I.

    1978-01-01

    On the basis of a critical analysis of the available data on causes and consequences of radiation accidents (RA), a classification of RA by severity (five groups of accidents) according to biomedical consequences and categories of exposed personnel is proposed. A RA is defined and its main characteristics are described. Methods of RA prevention are proposed, as is a plan of specific measures to deal with RA in accordance with the proposed classification

  3. Radiation retinopathy

    International Nuclear Information System (INIS)

    Wara, W.M.; Irvine, A.R.; Neger, R.E.; Howes, E.L. Jr.; Phillips, T.L.

    1979-01-01

    The records were reviewed of all patients treated with irradiation to the eye at the University of California, San Francisco, between 1960 and 1975. Eight patients were identified who had developed radiation retinopathy 1 to 3 years postrirradiation. Lesions included retinal vascular occlusions, hemorrhages, microaneurysms, exudates, neovascularization, vitreous hemorrhage, retinal detachments, and optic atrophy with blindness. Four patients had received less than 5000 rad in 6 weeks to the retina, a dose usually considered within normal tissue tolerance

  4. Space Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Corliss, William R.

    1968-01-01

    This booklet discusses three kinds of space radiation, cosmic rays, Van Allen Belts, and solar plasma. Cosmic rays are penetrating particles that we cannot see, hear or feel, which come from distant stars. Van Allen Belts, named after their discoverer are great belts of protons and electrons that the earth has captured in its magnetic trap. Solar plasma is a gaseous, electrically neutral mixture of positive and negative ions that the sun spews out from convulsed regions on its surface.

  5. Radiation smog

    International Nuclear Information System (INIS)

    Spurny, Z.

    1988-01-01

    The principle is described of the production of radiation smog resulting from radioactive emisions. The differences are discussed in the contamination over the territory of Czechoslovakia following the Chernobyl accident. The higher surface contamination of industrial areas recorded after the accident can be explained by electroprecipitation of industrial impurities with the radicals and ions of the radioactive cloud. (E.S.). 3 figs., 16 refs

  6. Adaptive protection scheme

    Directory of Open Access Journals (Sweden)

    R. Sitharthan

    2016-09-01

    Full Text Available This paper aims at modelling an electronically coupled distributed energy resource with an adaptive protection scheme. The electronically coupled distributed energy resource is a microgrid framework formed by coupling the renewable energy source electronically. Further, the proposed adaptive protection scheme provides a suitable protection to the microgrid for various fault conditions irrespective of the operating mode of the microgrid: namely, grid connected mode and islanded mode. The outstanding aspect of the developed adaptive protection scheme is that it monitors the microgrid and instantly updates relay fault current according to the variations that occur in the system. The proposed adaptive protection scheme also employs auto reclosures, through which the proposed adaptive protection scheme recovers faster from the fault and thereby increases the consistency of the microgrid. The effectiveness of the proposed adaptive protection is studied through the time domain simulations carried out in the PSCAD⧹EMTDC software environment.

  7. Origins of adaptive immunity.

    Science.gov (United States)

    Liongue, Clifford; John, Liza B; Ward, Alister

    2011-01-01

    Adaptive immunity, involving distinctive antibody- and cell-mediated responses to specific antigens based on "memory" of previous exposure, is a hallmark of higher vertebrates. It has been argued that adaptive immunity arose rapidly, as articulated in the "big bang theory" surrounding its origins, which stresses the importance of coincident whole-genome duplications. Through a close examination of the key molecules and molecular processes underpinning adaptive immunity, this review suggests a less-extreme model, in which adaptive immunity emerged as part of longer evolutionary journey. Clearly, whole-genome duplications provided additional raw genetic materials that were vital to the emergence of adaptive immunity, but a variety of other genetic events were also required to generate some of the key molecules, whereas others were preexisting and simply co-opted into adaptive immunity.

  8. Radiation pager

    International Nuclear Information System (INIS)

    Warren, J.L.; Vadnais, K.G.

    1998-01-01

    Methods of interdicting nuclear materials to date have favored the use of large portal detectors at choke points, or hand carried instruments used by trained personnel for conducting spot searches. Although these methods are effective in some instances, it is often impractical to insert choke points at busy traffic areas, and it is not cost effective to maintain a force of skilled operators whose focus is nuclear interdiction. Recent technology developments are causing profound changes in the philosophy and methods employed for interdicting nuclear materials. Breakthrough advances in the miniaturization of detectors and low power electronics have made possible a new class of small gamma-ray radiation detectors, roughly the size of a message pager, with unprecedented sensitivity for their size. These instruments, named Radiation Pagers TM , are ideally suited for use by untrained individual law enforcement personnel and emergency responders in the course of their regular duties. New tactics that utilize a radiation detector worn by every officer are creating a moving curtain of detection with a significantly higher likelihood of locating illicit nuclear contraband. These individual detectors also provide each officer with a high level of confidence that they are not being unknowingly irradiated in the course of their work. (author)

  9. Adaptation as organism design

    OpenAIRE

    Gardner, Andy

    2009-01-01

    The problem of adaptation is to explain the apparent design of organisms. Darwin solved this problem with the theory of natural selection. However, population geneticists, whose responsibility it is to formalize evolutionary theory, have long neglected the link between natural selection and organismal design. Here, I review the major historical developments in theory of organismal adaptation, clarifying what adaptation is and what it is not, and I point out future avenues for research.

  10. The purpose of adaptation

    OpenAIRE

    Gardner, Andy

    2017-01-01

    A central feature of Darwin’s theory of natural selection is that it explains the purpose of biological adaptation. Here, I: emphasise the scientific importance of understanding what adaptations are for, in terms of facilitating the derivation of empirically-testable predictions; discuss the population genetical basis for Darwin’s theory of the purpose of adaptation, with reference to the “fundamental theorem of natural selection”; and show that a deeper understanding of the purpose of adapta...

  11. Adaptive Multimedia Retrieval: Semantics, Context, and Adaptation

    DEFF Research Database (Denmark)

    This book constitutes the thoroughly refereed post-conference proceedings of the 10th International Conference on Adaptive Multimedia Retrieval, AMR 2012, held in Copenhagen, Denmark, in October 2012. The 17 revised full papers presented were carefully reviewed and selected from numerous submissi......This book constitutes the thoroughly refereed post-conference proceedings of the 10th International Conference on Adaptive Multimedia Retrieval, AMR 2012, held in Copenhagen, Denmark, in October 2012. The 17 revised full papers presented were carefully reviewed and selected from numerous...

  12. Quantifying the Adaptive Cycle.

    Directory of Open Access Journals (Sweden)

    David G Angeler

    Full Text Available The adaptive cycle was proposed as a conceptual model to portray patterns of change in complex systems. Despite the model having potential for elucidating change across systems, it has been used mainly as a metaphor, describing system dynamics qualitatively. We use a quantitative approach for testing premises (reorganisation, conservatism, adaptation in the adaptive cycle, using Baltic Sea phytoplankton communities as an example of such complex system dynamics. Phytoplankton organizes in recurring spring and summer blooms, a well-established paradigm in planktology and succession theory, with characteristic temporal trajectories during blooms that may be consistent with adaptive cycle phases. We used long-term (1994-2011 data and multivariate analysis of community structure to assess key components of the adaptive cycle. Specifically, we tested predictions about: reorganisation: spring and summer blooms comprise distinct community states; conservatism: community trajectories during individual adaptive cycles are conservative; and adaptation: phytoplankton species during blooms change in the long term. All predictions were supported by our analyses. Results suggest that traditional ecological paradigms such as phytoplankton successional models have potential for moving the adaptive cycle from a metaphor to a framework that can improve our understanding how complex systems organize and reorganize following collapse. Quantifying reorganization, conservatism and adaptation provides opportunities to cope with the intricacies and uncertainties associated with fast ecological change, driven by shifting system controls. Ultimately, combining traditional ecological paradigms with heuristics of complex system dynamics using quantitative approaches may help refine ecological theory and improve our understanding of the resilience of ecosystems.

  13. Adaptive Wireless Transceiver Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Wireless technologies are an increasingly attractive means for spatial data, input, manipulation, and distribution. Mobitrum is proposing an innovative Adaptive...

  14. Adaptive optics in microscopy.

    Science.gov (United States)

    Booth, Martin J

    2007-12-15

    The imaging properties of optical microscopes are often compromised by aberrations that reduce image resolution and contrast. Adaptive optics technology has been employed in various systems to correct these aberrations and restore performance. This has required various departures from the traditional adaptive optics schemes that are used in astronomy. This review discusses the sources of aberrations, their effects and their correction with adaptive optics, particularly in confocal and two-photon microscopes. Different methods of wavefront sensing, indirect aberration measurement and aberration correction devices are discussed. Applications of adaptive optics in the related areas of optical data storage, optical tweezers and micro/nanofabrication are also reviewed.

  15. Quantifying the adaptive cycle

    Science.gov (United States)

    Angeler, David G.; Allen, Craig R.; Garmestani, Ahjond S.; Gunderson, Lance H.; Hjerne, Olle; Winder, Monika

    2015-01-01

    The adaptive cycle was proposed as a conceptual model to portray patterns of change in complex systems. Despite the model having potential for elucidating change across systems, it has been used mainly as a metaphor, describing system dynamics qualitatively. We use a quantitative approach for testing premises (reorganisation, conservatism, adaptation) in the adaptive cycle, using Baltic Sea phytoplankton communities as an example of such complex system dynamics. Phytoplankton organizes in recurring spring and summer blooms, a well-established paradigm in planktology and succession theory, with characteristic temporal trajectories during blooms that may be consistent with adaptive cycle phases. We used long-term (1994–2011) data and multivariate analysis of community structure to assess key components of the adaptive cycle. Specifically, we tested predictions about: reorganisation: spring and summer blooms comprise distinct community states; conservatism: community trajectories during individual adaptive cycles are conservative; and adaptation: phytoplankton species during blooms change in the long term. All predictions were supported by our analyses. Results suggest that traditional ecological paradigms such as phytoplankton successional models have potential for moving the adaptive cycle from a metaphor to a framework that can improve our understanding how complex systems organize and reorganize following collapse. Quantifying reorganization, conservatism and adaptation provides opportunities to cope with the intricacies and uncertainties associated with fast ecological change, driven by shifting system controls. Ultimately, combining traditional ecological paradigms with heuristics of complex system dynamics using quantitative approaches may help refine ecological theory and improve our understanding of the resilience of ecosystems.

  16. Applications of nuclear radiations

    International Nuclear Information System (INIS)

    Hanagodimath, S.M.

    2012-01-01

    Nuclear radiations are powerful and non destructive tools in industry, medicine, defence, agriculture and research. In the present lecture, the types of nuclear radiations, radiation sources, detection of radiation, uses of radiation, dangers of nuclear radiation and nuclear energy will be discussed. (author)

  17. Perspective of radiation processing

    International Nuclear Information System (INIS)

    Zhang Manwei

    1987-01-01

    The area of the applications of radiation techniques is very wide. This paper only relates to the applications of radiation techniques in industries including radiation chemical industry, radiation processing of foods and environmental protection by radiation, but the nuclear instruments and the instrumentations of radiation are out-side of our study. (author)

  18. Gene adaptation to extreme environments

    International Nuclear Information System (INIS)

    Marlaire, P.; Rodriguez, V.; Kerner, N.

    2005-01-01

    Full text: This work is oriented to the study of gene adaptation to extreme conditions, such as the hydrothermal system located in Copahue, Neuquen, Argentina. The organisms living there develop under two pressure selection conditions: the high temperature of thermal water and the strong impact of ultraviolet (UV) radiation. Several microorganisms found in this region were isolated and different colonies resistant to UV radiation were selected, a Geobacillus thermoleovorans strain identified through 16S RNA sequence, being the most remarkable. A gene library was prepared out of this strain with UV sensitive bacteria BH200 (uvrA::Tn10). A number of clones were isolated by means of UV selection, the most outstanding being a gene carrier able to codify for the guanosine monophosphate synthetase enzyme (GMPs). The suitability of said enzyme was proved by means of additional assays performed on ght 1 bacteria (guaA26::Tn 10) which lacked the enzyme. A transcript of 1100 pb was detected through Northern Blot. The result was consistent with that obtained for the mapping of the starting transcription site. The cloned GMPs produces an increase in growth speed and a greater biomass in BH200 bacteria. (author)

  19. Effect of low doses of ionizing radiation on human health

    International Nuclear Information System (INIS)

    Kovalenko, A.N.

    1990-01-01

    Data are reported on the possible mechanism of biological effects of low doses of ionizing radiation on the human body. The lesioning effect of this radiation resulted in some of the persons in the development of disorders of the function of information and vegetative-regulatory systems determined as a desintegration syndrome. This syndrome is manifested in unspecific neuro-vegetative disorders of the function of most important physiological and homeostatic system of the body leading to weakening of the processes of compensation and adaptation. This condition is characterized by an unspecific radiation syndrome as distinct from acute or chronic radiation disease which is a specific radiation syndrome

  20. The RAGE radiation-hydrodynamic code

    Energy Technology Data Exchange (ETDEWEB)

    Gittings, Michael; Clover, Michael; Betlach, Thomas; Byrne, Nelson; Ranta, Dale [Science Applications International Corp. MS A-1, 10260 Campus Point Drive, San Diego, CA 92121 (United States); Weaver, Robert; Coker, Robert; Dendy, Edward; Hueckstaedt, Robert; New, Kim; Oakes, W Rob [Los Alamos National Laboratory, MS T087, PO Box 1663, Los Alamos, NM 87545 (United States); Stefan, Ryan [TaylorMade-adidas Golf, 5545 Fermi Court, Carlsbad, CA 92008-7324 (United States)], E-mail: michael.r.clover@saic.com

    2008-10-01

    We describe RAGE, the 'radiation adaptive grid Eulerian' radiation-hydrodynamics code, including its data structures, its parallelization strategy and performance, its hydrodynamic algorithm(s), its (gray) radiation diffusion algorithm, and some of the considerable amount of verification and validation efforts. The hydrodynamics is a basic Godunov solver, to which we have made significant improvements to increase the advection algorithm's robustness and to converge stiffnesses in the equation of state. Similarly, the radiation transport is a basic gray diffusion, but our treatment of the radiation-material coupling, wherein we converge nonlinearities in a novel manner to allow larger timesteps and more robust behavior, can be applied to any multi-group transport algorithm.

  1. The RAGE radiation-hydrodynamic code

    International Nuclear Information System (INIS)

    Gittings, Michael; Clover, Michael; Betlach, Thomas; Byrne, Nelson; Ranta, Dale; Weaver, Robert; Coker, Robert; Dendy, Edward; Hueckstaedt, Robert; New, Kim; Oakes, W Rob; Stefan, Ryan

    2008-01-01

    We describe RAGE, the 'radiation adaptive grid Eulerian' radiation-hydrodynamics code, including its data structures, its parallelization strategy and performance, its hydrodynamic algorithm(s), its (gray) radiation diffusion algorithm, and some of the considerable amount of verification and validation efforts. The hydrodynamics is a basic Godunov solver, to which we have made significant improvements to increase the advection algorithm's robustness and to converge stiffnesses in the equation of state. Similarly, the radiation transport is a basic gray diffusion, but our treatment of the radiation-material coupling, wherein we converge nonlinearities in a novel manner to allow larger timesteps and more robust behavior, can be applied to any multi-group transport algorithm

  2. Advances in radiation therapy dosimetry

    Directory of Open Access Journals (Sweden)

    Paliwal Bhudatt

    2009-01-01

    Full Text Available During the last decade, there has been an explosion of new radiation therapy planning and delivery tools. We went through a rapid transition from conventional three-dimensional (3D conformal radiation therapy to intensity-modulated radiation therapy (IMRT treatments, and additional new techniques for motion-adaptive radiation therapy are being introduced. These advances push the frontiers in our effort to provide better patient care; and with the addition of IMRT, temporal dimensions are major challenges for the radiotherapy patient dosimetry and delivery verification. Advanced techniques are less tolerant to poor implementation than are standard techniques. Mis-administrations are more difficult to detect and can possibly lead to poor outcomes for some patients. Instead of presenting a manual on quality assurance for radiation therapy, this manuscript provides an overview of dosimetry verification tools and a focused discussion on breath holding, respiratory gating and the applications of four-dimensional computed tomography in motion management. Some of the major challenges in the above areas are discussed.

  3. Non-ionizing radiation

    International Nuclear Information System (INIS)

    Tyrrell, R.M.; Pourzand, C.; Zhong, J.L.

    2003-01-01

    The ultraviolet A (320 - 380 nm) component of sunlight generates an oxidative stress in skin which contributes to both the acute (sunburn) and chronic (aging, skin cancer) effects of sunlight. The damaging effects occur via generation of active oxygen species and will be exacerbated by the presence of catalytically reactive iron so that the observation that UVA radiation causes an immediate release of 'free' iron in human skin fibroblasts and keratinocytes via the proteolysis of ferritin is likely to be biologically significant. UVA radiation also breaks down heme-containing proteins in the microsomal membrane to release free heme. The well-characterised activation of heme oxygenase 1 by UVA radiation will lead to breakdown of heme and further release of iron. Overall these interactions generate a strong oxidative stress on cells. Both the basal and UVA-induced levels of labile iron are 2-4 times higher in fibroblasts than keratinocytes and this is consistent with the higher resistance of keratinocytes to UVA-induced necrotic cell death. Modulating cellular iron levels by hemin (to enhance the levels) or iron chelators (to reduce the levels) has the predicted effect on levels of necrotic cell death. Overall these studies further illustrate the potent oxidising nature of UVA radiation. A series of genes activated by UVA radiation including heme oxygenase 1 (HO-1), ferritin and superoxide dismutase (SOD) may be involved in protection against the damaging effects of this oxidising carcinogen. HO will act by removing free heme and possibly by promoting the efflux of free iron, ferritin will bind free iron and SOD will remove superoxide anion. The strong response of HO-1 to oxidants in human skin fibroblasts provides a useful molecular model to study this inducible enzyme which appears to play a major role in anti-inflammatory activity in mammals and could play a significant role in preventing atherosclerosis. Several indirect lines of evidence support the role of UVA

  4. Integration of video and radiation analysis data

    Energy Technology Data Exchange (ETDEWEB)

    Menlove, H.O.; Howell, J.A.; Rodriguez, C.A.; Eccleston, G.W.; Beddingfield, D.; Smith, J.E. [Los Alamos National Lab., NM (United States); Baumgart, C.W. [EG and G Energy Measurements, Inc., Los Alamos, NM (United States)

    1994-08-01

    We have introduced a new method to integrate spatial (digital video) and time (radiation monitoring) information. This technology is based on pattern recognition by neural networks, provides significant capability to analyze complex data, and has the ability to learn and adapt to changing situations. This technique could significantly reduce the frequency of inspection visits to key facilities without a loss of safeguards effectiveness.

  5. Radiation-induced neurobehavioral dysfunctions

    International Nuclear Information System (INIS)

    Manda, Kailash

    2013-01-01

    There is a lacuna between sparsely reported immediate effects and the well documented delayed effects on cognitive functions seen after ionizing radiation exposure. We reported the radiation-dose dependent incongruity in the early cognitive changes and its correlation with the structural aberration as reported by imaging study. The delayed effect of radiation was investigated to understand the role of hippocampal neurogenesis in the functional recovery of cognition. C57BL/6 mice were exposed to different doses of γ-radiation and 24 hrs after exposure, the stress and anxiety levels were examined in the Open Field Exploratory Paradigms (OFT). 48hrs after irradiation, the hippocampal dependent recognition memory was observed by the Novel Object Recognition Test (NORT) and the cognitive function related to memory processing and recall was tested using the Elevated Plus Maze (EPM). Visualization of damage to the brain was done by diffusion tensor imaging at 48 hours post-irradiation. Results indicate a complex dose independent effect on the cognitive functions immediately after exposure to gamma rays. Radiation exposure caused short term memory dysfunctions at lower doses which were seen to be abrogated at higher doses, but the long term memory processing was disrupted at higher doses. The Hippocampus emerged as one of the sensitive regions to be affected by whole body exposure to gamma rays, which led to profound immediate alterations in cognitive functions. Furthermore, the results indicate a cognitive recovery process, which might be dependent on the extent of damage to the hippocampal region. While evaluating the delayed effect of radiation on the hippocampal neurogenesis, we observed that higher doses groups showed comparatively more adaptive regenerative neurogenic potential which they could not sustain at later stages. Our studies reported an important hitherto uncovered phenomenon of neurobehavioral dysfunctions in relation to radiation dose. Nevertheless, a

  6. Performance evaluation of ventilation radiators

    International Nuclear Information System (INIS)

    Myhren, Jonn Are; Holmberg, Sture

    2013-01-01

    A ventilation radiator is a combined ventilation and heat emission unit currently of interest due to its potential for increasing energy efficiency in exhaust-ventilated buildings with warm water heating. This paper presents results of performance tests of several ventilation radiator models conducted under controlled laboratory conditions. The purpose of the study was to validate results achieved by Computational Fluid Dynamics (CFD) in an earlier study and identify possible improvements in the performance of such systems. The main focus was on heat transfer from internal convection fins, but comfort and health aspects related to ventilation rates and air temperatures were also considered. The general results from the CFD simulations were confirmed; the heat output of ventilation radiators may be improved by at least 20% without sacrificing ventilation efficiency or thermal comfort. Improved thermal efficiency of ventilation radiators allows a lower supply water temperature and energy savings both for heating up and distribution of warm water in heat pumps or district heating systems. A secondary benefit is that a high ventilation rate can be maintained all year around without risk for cold draught. -- Highlights: ► Low temperature heat emitters are currently of interest due to their potential for increasing energy efficiency. ► A ventilation radiator is a combined ventilation and heat emission unit which can be adapted to low temperature heating systems. ► We examine how ventilation radiators can be made to be more efficient in terms of energy consumption and thermal comfort. ► Current work focuses on heat transfer mechanisms and convection fin configuration of ventilation radiators

  7. Adaptive Wavelet Transforms

    Energy Technology Data Exchange (ETDEWEB)

    Szu, H.; Hsu, C. [Univ. of Southwestern Louisiana, Lafayette, LA (United States)

    1996-12-31

    Human sensors systems (HSS) may be approximately described as an adaptive or self-learning version of the Wavelet Transforms (WT) that are capable to learn from several input-output associative pairs of suitable transform mother wavelets. Such an Adaptive WT (AWT) is a redundant combination of mother wavelets to either represent or classify inputs.

  8. Management for adaptation

    Science.gov (United States)

    John Innes; Linda A. Joyce; Seppo Kellomaki; Bastiaan Louman; Aynslie Ogden; Ian Thompson; Matthew Ayres; Chin Ong; Heru Santoso; Brent Sohngen; Anita Wreford

    2009-01-01

    This chapter develops a framework to explore examples of adaptation options that could be used to ensure that the ecosystem services provided by forests are maintained under future climates. The services are divided into broad areas within which managers can identify specific management goals for individual forests or landscapes. Adaptation options exist for the major...

  9. Detachable caster adapter

    Science.gov (United States)

    Mohr, R. J.

    1969-01-01

    Detachable caster adapter moves heavy welding tables when fork lift trucks are not practical. A support saddle on the adapter, connected to the caster platform by means of a hinge, fits the leg of the welding table, but can be modified to fit other leg configurations.

  10. Human pathogen avoidance adaptations

    NARCIS (Netherlands)

    Tybur, J.M.; Lieberman, D.

    2016-01-01

    Over the past few decades, researchers have become increasingly interested in the adaptations guiding the avoidance of disease-causing organisms. Here we discuss the latest developments in this area, including a recently developed information-processing model of the adaptations underlying pathogen

  11. Adaptation investments and homeownership

    DEFF Research Database (Denmark)

    Hansen, Jørgen Drud; Skak, Morten

    2008-01-01

    the home through a supplementary investment. Ownership offers low costs of adaptation, but has high contract costs compared with renting. Consumers simultaneously decide housing demand and tenure, and because of the different cost structure only consumers with strong preferences for individual adaptation...

  12. Adaptation investments and homeownership

    DEFF Research Database (Denmark)

    Hansen, Jørgen Drud; Skak, Morten

    2008-01-01

    by adapting the home through a supplementary investment. Ownership offers low costs of adaptation, but has high contract costs compared with renting. Consumers simultaneously choose housing demand and tenure, and because of the different cost structure only consumers with strong preferences for individual...

  13. Introduction: Adapting Idols

    NARCIS (Netherlands)

    Joost Bruin; dr. Koos Zwaan

    2012-01-01

    Introduction book Adapting Idols Since the first series of Pop Idol aired in the UK just over a decade ago, Idols television shows have been broadcast in more than forty countries all over the world. In all those countries the global Idols format has been adapted to local cultures and production

  14. Radiation danger

    International Nuclear Information System (INIS)

    Gergely, S.M.

    1986-01-01

    The author is a journalist and has written the book 4 weeks after the Chernobyl accident because 'the experts have failed in informing on the consequences of Chernobyl in a way to keep the insecurity in the population within tolerable limits'. It is aimed at the interested layman. First the events as seen through the Austria media and the measures taken by the authorities during the 4 weeks are reviewed. In the rest of the books there is elementary information on some aspects of radioactivity, reactors and radiation limits although 'the connection between radioactivity and health is very complex'. (G.Q.)

  15. Adaptive noise cancellation

    International Nuclear Information System (INIS)

    Akram, N.

    1999-01-01

    In this report we describe the concept of adaptive noise canceling, an alternative method of estimating signals corrupted by additive noise of interference. The method uses 'primary' input containing the corrupted signal and a 'reference' input containing noise correlated in some unknown way with the primary noise, the reference input is adaptively filtered and subtracted from the primary input to obtain the signal estimate. Adaptive filtering before subtraction allows the treatment of inputs that are deterministic or stochastic, stationary or time variable. When the reference input is free of signal and certain other conditions are met then noise in the primary input can be essentially eliminated without signal distortion. It is further shown that the adaptive filter also acts as notch filter. Simulated results illustrate the usefulness of the adaptive noise canceling technique. (author)

  16. Turbine system and adapter

    Energy Technology Data Exchange (ETDEWEB)

    Hogberg, Nicholas Alvin; Garcia-Crespo, Andres Jose

    2017-05-30

    A turbine system and adapter are disclosed. The adapter includes a turbine attachment portion having a first geometry arranged to receive a corresponding geometry of a wheelpost of a turbine rotor, and a bucket attachment portion having a second geometry arranged to receive a corresponding geometry of a root portion of a non-metallic turbine bucket. Another adapter includes a turbine attachment portion arranged to receive a plurality of wheelposts of a turbine rotor, and a bucket attachment portion arranged to receive a plurality of non-metallic turbine buckets having single dovetail configuration root portions. The turbine system includes a turbine rotor wheel configured to receive metal buckets, at least one adapter secured to at least one wheelpost on the turbine rotor wheel, and at least one non-metallic bucket secured to the at least one adapter.

  17. Appraising Adaptive Management

    Directory of Open Access Journals (Sweden)

    Kai N. Lee

    1999-12-01

    Full Text Available Adaptive management is appraised as a policy implementation approach by examining its conceptual, technical, equity, and practical strengths and limitations. Three conclusions are drawn: (1 Adaptive management has been more influential, so far, as an idea than as a practical means of gaining insight into the behavior of ecosystems utilized and inhabited by humans. (2 Adaptive management should be used only after disputing parties have agreed to an agenda of questions to be answered using the adaptive approach; this is not how the approach has been used. (3 Efficient, effective social learning, of the kind facilitated by adaptive management, is likely to be of strategic importance in governing ecosystems as humanity searches for a sustainable economy.

  18. Adaptive Processes in Hearing

    DEFF Research Database (Denmark)

    Santurette, Sébastien; Christensen-Dalsgaard, Jakob; Tranebjærg, Lisbeth

    2018-01-01

    induced by hearing impairment and the compensation provided by hearing devices. These devices themselves are now able to adapt to the listener’s individual environment, attentional state, and behavior. These topics related to auditory adaptation, in the broad sense of the term, were central to the 6th......Our auditory environment is constantly changing and evolving over time, requiring us to rapidly adapt to a complex dynamic sensory input. This adaptive ability of our auditory system can be observed at different levels, from individual cell responses to complex neural mechanisms and behavior...... International Symposium on Auditory and Audiological Research held in Nyborg, Denmark, in August 2017. The symposium addressed adaptive processes in hearing from different angles, together with a wide variety of other auditory and audiological topics. The papers in this special issue result from some...

  19. Adaptive signal processor

    Energy Technology Data Exchange (ETDEWEB)

    Walz, H.V.

    1980-07-01

    An experimental, general purpose adaptive signal processor system has been developed, utilizing a quantized (clipped) version of the Widrow-Hoff least-mean-square adaptive algorithm developed by Moschner. The system accommodates 64 adaptive weight channels with 8-bit resolution for each weight. Internal weight update arithmetic is performed with 16-bit resolution, and the system error signal is measured with 12-bit resolution. An adapt cycle of adjusting all 64 weight channels is accomplished in 8 ..mu..sec. Hardware of the signal processor utilizes primarily Schottky-TTL type integrated circuits. A prototype system with 24 weight channels has been constructed and tested. This report presents details of the system design and describes basic experiments performed with the prototype signal processor. Finally some system configurations and applications for this adaptive signal processor are discussed.

  20. Adaptive signal processor

    International Nuclear Information System (INIS)

    Walz, H.V.

    1980-07-01

    An experimental, general purpose adaptive signal processor system has been developed, utilizing a quantized (clipped) version of the Widrow-Hoff least-mean-square adaptive algorithm developed by Moschner. The system accommodates 64 adaptive weight channels with 8-bit resolution for each weight. Internal weight update arithmetic is performed with 16-bit resolution, and the system error signal is measured with 12-bit resolution. An adapt cycle of adjusting all 64 weight channels is accomplished in 8 μsec. Hardware of the signal processor utilizes primarily Schottky-TTL type integrated circuits. A prototype system with 24 weight channels has been constructed and tested. This report presents details of the system design and describes basic experiments performed with the prototype signal processor. Finally some system configurations and applications for this adaptive signal processor are discussed

  1. Transition and adaptation

    DEFF Research Database (Denmark)

    Andrade, Stefan Bastholm

    2015-01-01

    This article analyses how Danish farm families adapted to harsh and changing conditions in the period after the great western agricultural crisis in the early 1980s. Drawing on Bourdieu's concepts of habitus and adaptation, I analyse the creation and consolidation of different class fractions...... their agricultural production annually from 1980–2008. The result is a five-farmer typology that, together with logit regression models including background covariates, reveals how the farm families' adaptation strategies relate to educational level, financial situation, family composition and whether the farmer can...... amongst farm families due to different adaptation strategies. The data contain information about the population of self-employed farmers and their families who were between 30–35 years old in 1980 (n = 9,123). Using sequence analysis, I examine farm families' adaptation strategies for maintaining...

  2. Radiation risks and radiation protection at CRNL

    International Nuclear Information System (INIS)

    Myers, D.K.

    1986-01-01

    Radiation exposure is an occupational hazard at CRNL. The predicted health effects of low levels of radiation are described and compared with other hazards of living. Data related to the health of radiation workers are also considered. Special attention is given to the expected effects of radiation on the unborn child. Measures taken to protect CRNL employees against undue occupational exposure to radiation are noted

  3. Biological Effects of Ionizing Radiation

    International Nuclear Information System (INIS)

    Durand, J.L.

    2000-01-01

    The aim of this work is to verify the existence of the adaptive response phenomenon induced by low doses of ionizing radiation in living cells.A wild-type yeast Saccharomyces cerevisiae (Baker's yeast) was chosen as the biological target.As a parameter to quantify the sensibility of the target to radiation, the Lethal Dose 50 (LD50 ) was observed. In our experimental condition a value of (60 ± 1) Gy was measured for LD50 with Dose Rate of (0.44 ± 0.03) Gy/min. The method employed to show up the adaptive response phenomenon consisted in exposing the sample to low ''conditioning'' doses, which would initiate these mechanisms. Later the samples with and without conditioning were exposed to higher ''challenging'' doses (such as LD50), and the surviving fractions were compared. In order to maximize the differences, the doses and the time between irradiations were varied. The best results were obtained with both a conditioning dose of (0.44 ± 0.03) Gy and a waiting time of 2 hs until the application of the challenging dose. Following this procedures the 80% of the conditioned samples has survived, after receiving the application of the LD50. The adaptive response phenomenon was also verified for a wide range of challenging doses

  4. 75 FR 57859 - Specially Adapted Housing and Special Home Adaptation

    Science.gov (United States)

    2010-09-23

    ... Home Adaptation AGENCY: Department of Veterans Affairs. ACTION: Final rule. SUMMARY: The Department of... specially adapted housing and special home adaptation grants. This final rule incorporates certain... regulations pertaining to eligibility for specially adapted housing (SAH) grants and special home adaptation...

  5. Integral Radiator and Storage Tank

    Science.gov (United States)

    Burke, Kenneth A.; Miller, John R.; Jakupca, Ian; Sargi,Scott

    2007-01-01

    A simplified, lightweight system for dissipating heat of a regenerative fuel- cell system would include a heat pipe with its evaporator end placed at the heat source and its condenser end integrated into the wall of the regenerative fuel cell system gas-storage tanks. The tank walls act as heat-radiating surfaces for cooling the regenerative fuel cell system. The system was conceived for use in outer space, where radiation is the only physical mechanism available for transferring heat to the environment. The system could also be adapted for use on propellant tanks or other large-surface-area structures to convert them to space heat-radiating structures. Typically for a regenerative fuel cell system, the radiator is separate from the gas-storage tanks. By using each tank s surface as a heat-radiating surface, the need for a separate, potentially massive radiator structure is eliminated. In addition to the mass savings, overall volume is reduced because a more compact packaging scheme is possible. The underlying tank wall structure provides ample support for heat pipes that help to distribute the heat over the entire tank surface. The heat pipes are attached to the outer surface of each gas-storage tank by use of a high-thermal conductance, carbon-fiber composite-material wrap. Through proper choice of the composite layup, it is possible to exploit the high longitudinal conductivity of the carbon fibers (greater than the thermal conductivity of copper) to minimize the unevenness of the temperature distribution over the tank surface, thereby helping to maximize the overall heat-transfer efficiency. In a prototype of the system, the heat pipe and the composite wrap contribute an average mass of 340 g/sq m of radiator area. Lightweight space radiator panels have a mass of about 3,000 g/sq m of radiator area, so this technique saves almost 90 percent of the mass of separate radiator panels. In tests, the modified surface of the tank was found to have an emissivity of 0

  6. Synchrotron radiation

    International Nuclear Information System (INIS)

    Pattison, P.; Quinn, P.

    1990-01-01

    This report details the activities in synchrotron radiation and related areas at Daresbury Laboratory during 1989/90. The number and scope of the scientific reports submitted by external users and in-house staff is a reflection of the large amount of scheduled beamtime and high operating efficiency achieved at the Synchrotron Radiation Source (SRS) during the past year. Over 4000 hours of user beam were available, equivalent to about 80% of the total scheduled time. Many of the reports collected here illustrate the increasing technical complexity of the experiments now being carried out at Daresbury. Provision of the appropriate technical and scientific infrastructure and support is a continuing challenge. The development of the Materials Science Laboratory together with the existing Biological Support Laboratory will extend the range of experiments which can be carried out on the SRS. This will particularly facilitate work in which the sample must be prepared or characterised immediately before or during an experiment. The year 1989/90 has also seen a substantial upgrade of several stations, especially in the area of x-ray optics. Many of the advantages of the High Brightness Lattice can only be exploited effectively with the use of focusing optics. As the performance of these stations improves, the range of experiments which are feasible on the SRS will be extended significantly. (author)

  7. Radiation technology science

    International Nuclear Information System (INIS)

    Song, Jae Gwan

    1988-02-01

    This book deals with radiation technology and introduces various contents. It includes concept of radiation, fundamental physics, atom, electromagnetic radiation, electricity and magnetism, electromagnetism, interaction between X-rays and matter, process of latent image, intensifying screen, quality of radiography, special X-ray equipment, mammography, summary of computer, X-ray emission, nuclear magnetic resonance, grounded theory of radiation biology, initial effect of radiation, late effect of radiation, health physics, radiation protection, ultrasonic diagnosis.

  8. Basal DNA repair machinery is subject to positive selection in ionizing-radiation-resistant bacteria

    OpenAIRE

    Sghaier, Haïtham; Ghedira, Kaïs; Benkahla, Alia; Barkallah, Insaf

    2008-01-01

    Abstract Background Ionizing-radiation-resistant bacteria (IRRB) show a surprising capacity for adaptation to ionizing radiation and desiccation. Positive Darwinian selection is expected to play an important role in this trait, but no data are currently available regarding the role of positive adaptive selection in resistance to ionizing-radiation and tolerance of desiccation. We analyzed the four known genome sequences of IRRB (Deinococcus geothermalis, Deinococcus radiodurans, Kineococcus r...

  9. Fast Adaptive Beamforming with Smart Antenna for Radio Frequency Repeater

    Directory of Open Access Journals (Sweden)

    Wang Chaoqun

    2016-01-01

    Full Text Available We present a fast adaptive beamforming null algorithm with smart antenna for Radio Frequency Repeater (RFR. The smart antenna system is realized by a Direction Of Arrival (DOA Estimator, whose output is used by an adaptive beamforming algorithm to shape a suitable radiation pattern of the equivalent antenna; so that the co-channel interference due to retransmitting antenna can be reduced. The proposed adaptive beamforming algorithm, which has been proved by formulaic analysis and simulation, has a lower computation complexity yet better performance.

  10. Antiradiation Vaccine: Immunological neutralization of Radiation Toxins at Acute Radiation Syndromes.

    Science.gov (United States)

    Popov, Dmitri; Maliev, Slava

    Introduction: Current medical management of the Acute Radiation Syndromes (ARS) does not include immune prophylaxis based on the Antiradiation Vaccine. Existing principles for the treatment of acute radiation syndromes are based on the replacement and supportive therapy. Haemotopoietic cell transplantation is recomended as an important method of treatment of a Haemopoietic form of the ARS. Though in the different hospitals and institutions, 31 pa-tients with a haemopoietic form have previously undergone transplantation with stem cells, in all cases(100%) the transplantants were rejected. Lethality rate was 87%.(N.Daniak et al. 2005). A large amount of biological substances or antigens isolated from bacterias (flagellin and derivates), plants, different types of venom (honeybees, scorpions, snakes) have been studied. This biological active substances can produce a nonspecific stimulation of immune system of mammals and protect against of mild doses of irradiation. But their radioprotection efficacy against high doses of radiation were not sufficient. Relative radioprotection characteristics or adaptive properties of antioxidants were expressed only at mild doses of radiation. However antioxidants demonstrated a very low protective efficacy at high doses of radiation. Some ex-periments demonstrated even a harmful effect of antioxidants administered to animals that had severe forms of the ARS. Only Specific Radiation Toxins roused a specific antigenic stim-ulation of antibody synthesis. An active immunization by non-toxic doses of radiation toxins includes a complex of radiation toxins that we call the Specific Radiation Determinant (SRD). Immunization must be provided not less than 24 days before irradiation and it is effective up to three years and more. Active immunization by radiation toxins significantly reduces the mortality rate (100%) and improves survival rate up to 60% compare with the 0% sur-vival rate among the irradiated animals in control groups

  11. Biological effect of radiation on human

    International Nuclear Information System (INIS)

    Lee, Yun Sil; Cho, Chul Koo; Lee, Su Jae

    2000-04-01

    1. Adaptive response when 0.01 Gy was preirradiated before high challenging dose is induced in normal cell types such normal lymphocytes, primary keratinocytes, and L929 fibroblast cells but not in neoplastic cells such as L5178Y lymphoma cells, EL-4 lymphoma cells and 308 papilloma cells. 2. Heat shock protein (HSP) 25 and inducible HSP70 is responsible for the induction of adaptive response and radioresistance - cell cycle regulation, antiapoptotic molecule and PKC activation were involved. 3. Apoptosis was induced at most 5. hrs after irradiation in primary keratinocytes, in v-rasHa transformed keratinocytes, the maximum interval was 16 hrs, and in 308 papilloma cells, the maximum was 48 hrs. 4. PKC response by radiation is correlated with induction of apoptosis. 5. Rapid induction PKCdelta in primary keratinocytes and no response of PKC epsilon may involved in radiation induced apoptosis. 6. The rate of resorption was increased when radiation was given at 2.5 days after gestation. Early death including foetal death were highly expressed when radiation was given at 7.5 days after gestation. There are no difference in incidence of late death including embryonic death. 7. 2 Gy is the most effective dose in radiation induced teratogenesis in mouse model. 8. Growth retardation and small head was present when radiation was given at 5.5, 7.5, 11.5 and 15.5 days after gestation and small head showed high incidence at 11.5 days after gestation. 9. External malformation, internal malformation and skeletal malformation was induced when radiation was given at 7.5 days after gestation. 10. OGG1-mutated cells induced radiosensitive by G2/M cell cycle arrest. 11. Radiation induced G2/M phase cell cycle and correlated with radiosensitivity. 12. PKCalpha induced differentiation. 13. Radiation exposed cells showed carcinogenic effect. 14. Organ specific radiosensitivity was shown and protein expression was involved

  12. Biological effect of radiation on human

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yun Sil; Cho, Chul Koo; Lee, Su Jae [and others

    2000-04-01

    1. Adaptive response when 0.01 Gy was preirradiated before high challenging dose is induced in normal cell types such normal lymphocytes, primary keratinocytes, and L929 fibroblast cells but not in neoplastic cells such as L5178Y lymphoma cells, EL-4 lymphoma cells and 308 papilloma cells. 2. Heat shock protein (HSP) 25 and inducible HSP70 is responsible for the induction of adaptive response and radioresistance - cell cycle regulation, antiapoptotic molecule and PKC activation were involved. 3. Apoptosis was induced at most 5. hrs after irradiation in primary keratinocytes, in v-rasHa transformed keratinocytes, the maximum interval was 16 hrs, and in 308 papilloma cells, the maximum was 48 hrs. 4. PKC response by radiation is correlated with induction of apoptosis. 5. Rapid induction PKCdelta in primary keratinocytes and no response of PKC epsilon may involved in radiation induced apoptosis. 6. The rate of resorption was increased when radiation was given at 2.5 days after gestation. Early death including foetal death were highly expressed when radiation was given at 7.5 days after gestation. There are no difference in incidence of late death including embryonic death. 7. 2 Gy is the most effective dose in radiation induced teratogenesis in mouse model. 8. Growth retardation and small head was present when radiation was given at 5.5, 7.5, 11.5 and 15.5 days after gestation and small head showed high incidence at 11.5 days after gestation. 9. External malformation, internal malformation and skeletal malformation was induced when radiation was given at 7.5 days after gestation. 10. OGG1-mutated cells induced radiosensitive by G2/M cell cycle arrest. 11. Radiation induced G2/M phase cell cycle and correlated with radiosensitivity. 12. PKCalpha induced differentiation. 13. Radiation exposed cells showed carcinogenic effect. 14. Organ specific radiosensitivity was shown and protein expression was involved.

  13. [Adaptive optics for ophthalmology].

    Science.gov (United States)

    Saleh, M

    2016-04-01

    Adaptive optics is a technology enhancing the visual performance of an optical system by correcting its optical aberrations. Adaptive optics have already enabled several breakthroughs in the field of visual sciences, such as improvement of visual acuity in normal and diseased eyes beyond physiologic limits, and the correction of presbyopia. Adaptive optics technology also provides high-resolution, in vivo imaging of the retina that may eventually help to detect the onset of retinal conditions at an early stage and provide better assessment of treatment efficacy. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  14. Symmetry Adapted Basis Sets

    DEFF Research Database (Denmark)

    Avery, John Scales; Rettrup, Sten; Avery, James Emil

    In theoretical physics, theoretical chemistry and engineering, one often wishes to solve partial differential equations subject to a set of boundary conditions. This gives rise to eigenvalue problems of which some solutions may be very difficult to find. For example, the problem of finding...... in such problems can be much reduced by making use of symmetry-adapted basis functions. The conventional method for generating symmetry-adapted basis sets is through the application of group theory, but this can be difficult. This book describes an easier method for generating symmetry-adapted basis sets...

  15. Introduction to adaptive arrays

    CERN Document Server

    Monzingo, Bob; Haupt, Randy

    2011-01-01

    This second edition is an extensive modernization of the bestselling introduction to the subject of adaptive array sensor systems. With the number of applications of adaptive array sensor systems growing each year, this look at the principles and fundamental techniques that are critical to these systems is more important than ever before. Introduction to Adaptive Arrays, 2nd Edition is organized as a tutorial, taking the reader by the hand and leading them through the maze of jargon that often surrounds this highly technical subject. It is easy to read and easy to follow as fundamental concept

  16. Adapt or Die

    DEFF Research Database (Denmark)

    Brody, Joshua Eric; Larsen, Kasper Green

    2015-01-01

    In this paper, we study the role non-adaptivity plays in maintaining dynamic data structures. Roughly speaking, a data structure is non-adaptive if the memory locations it reads and/or writes when processing a query or update depend only on the query or update and not on the contents of previously...... read cells. We study such non-adaptive data structures in the cell probe model. This model is one of the least restrictive lower bound models and in particular, cell probe lower bounds apply to data structures developed in the popular word-RAM model. Unfortunately, this generality comes at a high cost...

  17. Fuzzy controller adaptation

    Science.gov (United States)

    Myravyova, E. A.; Sharipov, M. I.; Radakina, D. S.

    2017-10-01

    During writing this work, the fuzzy controller with a double base of rules was studied, which was applied for the synthesis of the automated control system. A method for fuzzy controller adaptation has been developed. The adaptation allows the fuzzy controller to automatically compensate for parametric interferences that occur at the control object. Specifically, the fuzzy controller controlled the outlet steam temperature in the boiler unit BKZ-75-39 GMA. The software code was written in the programming support environment Unity Pro XL designed for fuzzy controller adaptation.

  18. ULTRAVIOLET PROTECTIVE PIGMENTS AND DNA DIMER INDUCTION AS RESPONSES TO ULTRAVIOLET RADIATION

    Science.gov (United States)

    Life on Earth has evolved adaptations to many environmental stresses over the epochs. One consistent stress has been exposure to ultraviolet (UV) radiation. The most basic effect of UV radiation on biological systems is damage to DNA. In response to UV radiation organisms have ad...

  19. Transformer: an adaptation framework supporting contextual adaptation behavior composition

    OpenAIRE

    Gui, Ning; De Florio, Vincenzo; Holvoet, Tom

    2013-01-01

    As software systems today increasingly operate in changing and complex environments, they are expected to dynamically adapt to the changing environments sometimes with multiple co-existing adaptation goals. This paper proposes an adaptation framework to facilitate adaptation with multiple concerns by using reusable and composable adaptation modules. Rather than using one-size-fits-all approach, in this framework, system global adaptation behavior is generated by contextually fusin...

  20. Radiation biophysics

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Summaries of research projects conducted during 1978 and 1979 are presented. The overall thrust of the research is aimed at understanding the effects of radiation on organisms. Specific subject areas include: the effects of heavy-particle beam nuclear interactions in tissue on dosimetry; tracer studies with radioactive fragments of heavy-ion beams; the effects of heavy/ions on human kidney cells and Chinese hamster cells; the response of a rhabdomyosarcoma tumor system in rats to heavy-ion beams; the use of heavy charged particles in radiotherapy of human cancer; heavy-ion radiography; the biological effects of high magnetic fields; central nervous system neurotoxicity; and biophysical studies on cell membranes