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Sample records for aasmaa lya mgi

  1. Mouse Genome Informatics (MGI)

    Data.gov (United States)

    U.S. Department of Health & Human Services — MGI is the international database resource for the laboratory mouse, providing integrated genetic, genomic, and biological data to facilitate the study of human...

  2. What is the physical origin of strong Lya emission? II. Gas Kinematics and Distribution of Lya Emitters

    CERN Document Server

    Shibuya, Takatoshi; Nakajima, Kimihiko; Hashimoto, Takuya; Ono, Yoshiaki; Rauch, Michael; Gauthier, Jean-Rene; Shimasaku, Kazuhiro; Goto, Ryosuke; Mori, Masao; Umemura, Masayuki

    2014-01-01

    We present a statistical study of velocities of Lya, interstellar (IS) absorption, and nebular lines and gas covering fraction for Lya emitters (LAEs) at z~2. We make a sample of 22 LAEs with a large Lya equivalent width (EW) of > 50A based on our deep Keck/LRIS observations, in conjunction with spectroscopic data from the Subaru/FMOS program and the literature. We estimate the average velocity offset of Lya from a systemic redshift determined with nebular lines to be dv_Lya=234+-9 km s-1. Using a Kolmogorv-Smirnov test, we confirm the previous claim of Hashimoto et al. (2013) that the average dv_Lya of LAEs is smaller than that of LBGs. Our LRIS data successfully identify blue-shifted multiple IS absorption lines in the UV continua of four LAEs on an individual basis. The average velocity offset of IS absorption lines from a systemic redshift is dv_IS=204+-27 km s-1, indicating LAE's gas outflow with a velocity comparable to typical LBGs. Thus, the ratio, R^Lya_ IS = dv_Lya/dv_IS of LAEs, is around unity, su...

  3. The CALYMHA survey: Lya luminosity function and global escape fraction of Lya photons at z=2.23

    CERN Document Server

    Sobral, David; Best, Philip; Stroe, Andra; Röttgering, Huub; Oteo, Iván; Smail, Ian; Morabito, Leah; Paulino-Afonso, Ana

    2016-01-01

    We present the CAlibrating LYMan-$\\alpha$ with H$\\alpha$ (CALYMHA) pilot survey and new results on Lyman-$\\alpha$ (Lya) selected galaxies at z~2. We use a custom-built Lya narrow-band filter at the Isaac Newton Telescope, designed to provide a matched volume coverage to the z=2.23 Ha HiZELS survey. Here we present the first results for the COSMOS and UDS fields. Our survey currently reaches a 3$\\sigma$ line flux limit of ~4x10$^{-17}$ erg/s/cm$^{2}$, and a Lya luminosity limit of ~10$^{42.3}$ erg/s. We find 188 Lya emitters over 7.3x10$^5$ Mpc$^{3}$, but also find significant numbers of other line emitting sources corresponding to HeII, CIII] and CIV emission lines. These sources are important contaminants, and we carefully remove them, unlike most previous studies. We find that the Lya luminosity function at z=2.23 is very well described by a Schechter function up to L~10$^{43}$ erg/s with L$^*=10^{42.59+-0.05}$ erg/s, $\\phi^*=10^{-3.09+-0.08}$ Mpc$^{-3}$ and $\\alpha$=-1.75+-0.15. Above L~10$^{43}$ erg/s the...

  4. A Successful Broad-band Survey for Giant Lya Nebulae II: Spectroscopic Confirmation

    CERN Document Server

    Prescott, Moire K M; Jannuzi, Buell T

    2012-01-01

    Using a systematic broad-band search technique, we have carried out a survey for large Lya nebulae (or Lya "blobs") at 2Lya nebulae. Of 26 candidates targeted, 5 were confirmed to have Lya emission at 1.7Lya nebulae span a range of Lya equivalent widths, colors, sizes, and line ratios, and most show spatially-extended continuum emission. The remaining candidates did not reveal any strong emission lines, but instead exhibit featureless, diffuse, blue continuum spectra. Their nature remains mysterious, but we speculate that some of these might be Lya nebulae lying within the redshift desert (i.e., 1.2

  5. Probing the IGM/Galaxy Connection V: On the Origin of Lya and OVI Absorption at z<0.2

    CERN Document Server

    Prochaska, J Xavier; Chen, H -W; Mulchaey, J S; Cooksey, K L

    2011-01-01

    We analyze the association of galaxies to Lya and OVI absorption, the most commonly detected transitions in the low-z intergalactic medium (IGM), in the fields of 14 quasars with z_em = 0.06-0.57. Confirming previous studies, we observe a high covering fraction for Lya absorption to impact parameter rho = 300kpc: 33/37 of our L>0.01L* galaxies show Lya equivalent width W_Lya>50mA. Galaxies of all luminosity L>0.01L* and spectral type are surrounded by a diffuse and ionized circumgalactic medium (CGM), whose baryonic mass is estimated at ~10^(10.5 +/- 0.3) Msun for a constant N_H. The virialized halos and extended CGM of present-day galaxies are responsible for most strong Lya absorbers (W_Lya > 300mA) but cannot reproduce the majority of observed lines in the Lya forest. We conclude that the majority of Lya absorption with W_Lya=30-300mA occurs in the cosmic web predicted by cosmological simulations and estimate a characteristic width for these filaments of ~400kpc. Regarding OVI, we observe a near unity cove...

  6. Warm Gas in the Virgo Cluster: I. Distribution of Lya Absorbers

    CERN Document Server

    Yoon, Joo Heon; Thom, Christopher; Chen, Hsiao-Wen; Bryan, Greg

    2012-01-01

    The first systematic study of the warm gas (T=10^4-5 K) distribution across a galaxy cluster is presented using multiple background QSOs to the Virgo Cluster. We detect 25 Lya absorbers (N_HI = 10^13.1-15.4 cm^-2) in the Virgo velocity range toward 9 of 12 QSO sightlines observed with COS, with a cluster impact parameter range of 0.25-1.15 Mpc (0.23-1.05Rvir). Including 18 previously STIS or GHRS detected Lya absorbers toward 7 of 11 background QSOs in and around the Virgo Cluster, we establish a sample of 43 absorbers towards a total of 23 background probes for studying the incidence of Lya absorbers in and around the Virgo Cluster. With these absorbers, we find: 1) Warm gas is predominantly in the outskirts of the cluster and avoids the X-ray detected hot ICM. Also, Lya absorption strength increases with a cluster impact parameter. 2) Lya absorbing warm gas traces cold HI emitting gas in the substructures of the Virgo Cluster. 3) Including the absorbers associated with the surrounding substructures, the war...

  7. MouseMine: a new data warehouse for MGI.

    Science.gov (United States)

    Motenko, H; Neuhauser, S B; O'Keefe, M; Richardson, J E

    2015-08-01

    MouseMine (www.mousemine.org) is a new data warehouse for accessing mouse data from Mouse Genome Informatics (MGI). Based on the InterMine software framework, MouseMine supports powerful query, reporting, and analysis capabilities, the ability to save and combine results from different queries, easy integration into larger workflows, and a comprehensive Web Services layer. Through MouseMine, users can access a significant portion of MGI data in new and useful ways. Importantly, MouseMine is also a member of a growing community of online data resources based on InterMine, including those established by other model organism databases. Adopting common interfaces and collaborating on data representation standards are critical to fostering cross-species data analysis. This paper presents a general introduction to MouseMine, presents examples of its use, and discusses the potential for further integration into the MGI interface.

  8. Electron Theory Research in Mg-Y Alloy

    Institute of Scientific and Technical Information of China (English)

    郭旭涛; 何良菊; 李培杰; 曾大本

    2004-01-01

    Adding yttrium to magnesium can improve the mechanical properties,especially the mechanical behavior at high temperature.The valence electron structures of Mg-Y alloy were analyzed with the empirical electron theory of solids and molecules(EET).Calculation shows that yttrium is on the fifth hybrid level and magnesium is on the third one in pure metal crystals.By comparing with aluminum in Mg-Al alloy,it is shown that the reason why the solution strengthening effect of yttrium is better than that of aluminum in Mg-Al alloy is the enhanced bond energy according to EET.And it is concluded from EET analysis that intermetallics Mg24Y5 can significantly improve the properties of magnesium alloys because yttrium atoms occupy the centers of the octahedron and Mg-Y bonds efficiently strengthen the alloy matrix.

  9. Gravitationally Lensed Galaxies at 2Lya Emitters

    CERN Document Server

    Christensen, Lise; Richard, Johan; Hjorth, Jens; Milvang-Jensen, Bo; Dessauges-Zavadsky, Miroslava; Limousin, Marceau; Grillo, Claudio; Ebeling, Harald

    2012-01-01

    Strong gravitational lensing magnifies the flux from distant galaxies, allowing us to detect emission lines that would otherwise fall below the detection threshold for medium-resolution spectroscopy. Here we present the detection of temperature-sensitive oxygen emission lines from three galaxies at 22 for which this has been possible. The three galaxies have ~10% solar oxygen abundances in agreement with strong emission line diagnostics. Carbon and nitrogen ratios relative to oxygen are sub-solar as expected for young metal-poor galaxies. Two of the galaxies are Lya emitters with rest-frame equivalent widths of 60 A and 80 A, respectively, and their high magnification factors allow us for the first time to gain insight into the physical characteristics of high-redshift Lya emitters. Using constraints from the physical properties of the galaxies, we accurately reproduce their line profiles with radiative transfer models. The models show a relatively small outflow in agreement with the observed small velocity o...

  10. Multi-MGy Radiation Hardened Camera for Nuclear Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Girard, Sylvain; Boukenter, Aziz; Ouerdane, Youcef [Universite de Saint-Etienne, Lab. Hubert Curien, UMR-CNRS 5516, F-42000 Saint-Etienne (France); Goiffon, Vincent; Corbiere, Franck; Rolando, Sebastien; Molina, Romain; Estribeau, Magali; Avon, Barbara; Magnan, Pierre [ISAE, Universite de Toulouse, F-31055 Toulouse (France); Paillet, Philippe; Duhamel, Olivier; Gaillardin, Marc; Raine, Melanie [CEA, DAM, DIF, F-91297 Arpajon (France)

    2015-07-01

    There is an increasing interest in developing cameras for surveillance systems to monitor nuclear facilities or nuclear waste storages. Particularly, for today's and the next generation of nuclear facilities increasing safety requirements consecutive to Fukushima Daiichi's disaster have to be considered. For some applications, radiation tolerance needs to overcome doses in the MGy(SiO{sub 2}) range whereas the most tolerant commercial or prototypes products based on solid state image sensors withstand doses up to few kGy. The objective of this work is to present the radiation hardening strategy developed by our research groups to enhance the tolerance to ionizing radiations of the various subparts of these imaging systems by working simultaneously at the component and system design levels. Developing radiation-hardened camera implies to combine several radiation-hardening strategies. In our case, we decided not to use the simplest one, the shielding approach. This approach is efficient but limits the camera miniaturization and is not compatible with its future integration in remote-handling or robotic systems. Then, the hardening-by-component strategy appears mandatory to avoid the failure of one of the camera subparts at doses lower than the MGy. Concerning the image sensor itself, the used technology is a CMOS Image Sensor (CIS) designed by ISAE team with custom pixel designs used to mitigate the total ionizing dose (TID) effects that occur well below the MGy range in classical image sensors (e.g. Charge Coupled Devices (CCD), Charge Injection Devices (CID) and classical Active Pixel Sensors (APS)), such as the complete loss of functionality, the dark current increase and the gain drop. We'll present at the conference a comparative study between these radiation-hardened pixel radiation responses with respect to conventional ones, demonstrating the efficiency of the choices made. The targeted strategy to develop the complete radiation hard camera

  11. Constraining cosmic reionization with quasar, gamma ray burst, and Lya emitter observations

    CERN Document Server

    Gallerani, S; Choudhury, T R; Fan, X; Salvaterra, R; Dayal, P

    2009-01-01

    We investigate the cosmic reionization history by comparing semi-analytical models of the Lya forest with observations of high-z quasars and gamma ray bursts absorption spectra. In order to constrain the reionization epoch z_rei, we consider two physically motivated scenarios in which reionization ends either early (ERM, z_rei>= 7) or late (LRM, z_rei~6). We analyze the transmitted flux in a sample of 17 quasars spectra at 5.7=11 and completes at z_rei>=7, in agreement with the recent WMAP5 data.

  12. Submillimeter observations of the J2142-4423 Lya protocluster at z = 2.38

    CERN Document Server

    Beelen, A; Kovács, A; Lagache, G; De Breuck, C; Weiss, A; Menten, K M; Colbert, J W; Dole, H; Siringo, G; Kreysa, E

    2008-01-01

    We present observations aimed at exploring both the nature of Lya emitting nebulae (Lya blobs) at z=2.38 and the way they trace large scale structure (LSS), by exploring their proximity to maximum starbursts through submillimeter emission. Our most important objectives are to make a census of associated submillimeter galaxies (SMGs), check their properties, and look for a possible overdensity in the protocluster J2142-4426 at z=2.38. We used the newly commissioned Large APEX Bolometer Camera (LABoCa) on the Atacama Pathfinder EXperiment (APEX) telescope, in its Science Verification phase, to carry out a deep 10'x10' map at 870 micron, and we performed multiple checks of the quality of data processing and source extraction. Our map, the first published deep image, confirms the capabilities of APEX/LABoCa as the most efficient current equipment for wide and deep submm mapping. Twenty-two sources were securely extracted with 870 micron flux densities in the range 3-21 mJy, rms noise 0.8-2.4 mJy, and far-IR lumin...

  13. H I Column Densities, Metallicities, and Dust Extinction of Metal-Strong Damped Lya Systems

    CERN Document Server

    Kaplan, Kyle F; Herbert-Fort, Stephane; Ellison, Sara L; Dessauges-Zavadsky, Miroslava

    2010-01-01

    With the Blue Channel Spectrograph (BCS) on the MMT telescope, we have obtained spectra to the atmospheric cutoff of quasars previously known to show at least one absorption system at z>1.6 with very strong metal lines (candidate metal-strong damped Lya systems; cMSDLAs). The BCS/MMT spectra yield precise estimates of the HI column densities (NHI) of the systems through Voigt profile analysis of their Lya transitions. Nearly all of the cMSDLAs (41/43) satisfy the NHI criterion of DLAs, 10^20.3. As a population, these systems have systematically higher NHI values than DLAs chosen randomly from quasar sightlines. Combining our NHI measurements with previously measured metal column densities, we estimate metallicities for the MSDLAs. These systems have significantly higher values than randomly selected DLAs; at z~2, the MSDLAs show a median metallicity [M/H] ~ -0.67 that is 0.6dex higher than a corresponding control sample. This establishes MSDLAs as having amongst the most metal-rich gas in the high z universe....

  14. Elephant random walks and their connection to Pólya-type urns

    Science.gov (United States)

    Baur, Erich; Bertoin, Jean

    2016-11-01

    In this paper, we explain the connection between the elephant random walk (ERW) and an urn model à la Pólya and derive functional limit theorems for the former. The ERW model was introduced in [Phys. Rev. E 70, 045101 (2004), 10.1103/PhysRevE.70.045101] to study memory effects in a highly non-Markovian setting. More specifically, the ERW is a one-dimensional discrete-time random walk with a complete memory of its past. The influence of the memory is measured in terms of a memory parameter p between zero and one. In the past years, a considerable effort has been undertaken to understand the large-scale behavior of the ERW, depending on the choice of p . Here, we use known results on urns to explicitly solve the ERW in all memory regimes. The method works as well for ERWs in higher dimensions and is widely applicable to related models.

  15. The missing halide: Millimeter-wave spectroscopy of the MgI radical (X2Σ+)

    Science.gov (United States)

    Kilchenstein, K. M.; Halfen, D. T.; Ziurys, L. M.

    2017-09-01

    The pure rotational spectrum of the MgI radical in its ground electronic state (X2Σ+) has been measured using millimeter/submillimeter wave direct absorption techniques in the region of 200-300 GHz. The molecule was created in a DC discharge by the reaction of magnesium vapor, produced in a Broida-type oven, with CH3I. Between five to twelve transitions were recorded for the v = 0, 1, and 2 vibrational states of 24MgI, as well as the v = 0 state for the isotopologues 25MgI and 26MgI, measured in their natural magnesium abundance. All observed transitions exhibited large spin-rotation splittings. Rotational, centrifugal distortion, and spin-rotation constants were determined for each isotopologue and the excited vibrational states of 24MgI. Equilibrium parameters Be, αe, De, βe, γe and γe‧ were derived for the main isotopologue, as well as the equilibrium bond length, re = 2.5730 (1) Å. The large spin-rotation constant of γ ∼ 300 MHz in MgI is thought to arise from second-order spin-orbit coupling originating in the nearby A2Π state, with possible contributions from other excited 2Π states.

  16. To Stack or Not to Stack: Spectral Energy Distribution Properties of Lya-Emitting Galaxies at z=2.1

    CERN Document Server

    Vargas, Carlos J; Acquaviva, Viviana; Gawiser, Eric; Finkelstein, Steven L; Ciardullo, Robin; Ashby, Matthew L N; Feldmeier, John; Ferguson, Henry; Gronwall, Caryl; Guaita, Lucia; Hagen, Alex; Koekemoer, Anton; Kurczynski, Peter; Newman, Jeffrey A; Padilla, Nelson

    2013-01-01

    We use the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) GOODS-S multi-wavelength catalog to identify counterparts for 20 Lya Emitting (LAE) galaxies at z=2.1. We build several types of stacked Spectral Energy Distributions (SEDs) of these objects. We combine photometry to form average and median flux-stacked SEDs, and postage stamp images to form average and median image-stacked SEDs. We also introduce scaled flux stacks that eliminate the influence of variation in overall brightness. We use the SED fitting code SpeedyMC to constrain the physical properties of individual objects and stacks. Our LAEs at z = 2.1 have stellar masses ranging from 2x10^7 Sollar Masses - 8x10^9 Solar Masses (median = 3x10^8 Solar Masses), ages ranging from 4 Myr to 500 Myr (median =100 Myr), and E(B-V) between 0.02 and 0.24 (median = 0.12). We do not observe strong correlations between Lya equivalent width (EW) and stellar mass, age, or E(B-V). The Lya radiative transfer (q) factors of our sample are pre...

  17. A combined Pòlya process and mixture distribution approach to rainfall modelling

    Directory of Open Access Journals (Sweden)

    E. Todini

    1997-01-01

    Full Text Available A new probabilistic interpretation of at site rainfall sequences is introduced for the development of a stochastic model of rain. The model, is divided into two sub models; the first one describing the total number of rainfall spells within a window of time is described by a Pòlya process in order to reproduce better the variable probability of occurrence of rainfall during storm events (due to the presence of different numbers of rainfall cells; the second sub model, conditional on the first one, describes the total quantity of rainfall in the time window, given a number of rainfall spells. The probabilistic rainfall model, which has shown interesting properties in reproducing the probability distribution of observed data at time scales ranging from one hour to twenty-four hours, may be the basis for a number of applications which include the development of a conditional stochastic generator of rain, within the frame of real-time flood forecasting, and the derivation of a probabilistic distribution of rainfall extremes at the various time scales.

  18. A MGy Radiation-Hardened Sensor Instrumentation SoC in 65nm CMOS Technology

    OpenAIRE

    Verbeeck, Jens; Cao, Ying; Van Uffelen, Marco; Mont Casellas, Laura; Damiani, Carlo; Meek, Richard; Haist, Bernhard; Steyaert, Michiel; Leroux, Paul

    2014-01-01

    A radiation-hardened sensor instrumentation SoC is presented in this paper. The SoC is implemented in a standard 65nm CMOS technology, and achieves MGy-level TID radiation hardness through radiation-hardening-by-design.

  19. Resolving the optical emission lines of Lya blob 'B1' at z=2.38: another hidden quasar

    OpenAIRE

    Overzier, R. A.; Nesvadba, N. P. H.; Dijkstra, M.; Hatch, N. A.; Lehnert, M.D.; Villar-Martín, M.; Wilman, R. J.; Zirm, A. W.

    2013-01-01

    We have used the SINFONI near-infrared integral field unit on the VLT to resolve the optical emission line structure of one of the brightest (L~1e44 erg/s) and nearest (z=2.38) of all Lya blobs (LABs). The target, known in the literature as object 'B1' (Francis et al. 1996), lies at a redshift where the main optical emission lines are accessible in the observed near-infrared. We detect luminous [OIII]4959,5007A and Ha emission with a spatial extent of at least 32x40 kpc (4"x5"). The dominant ...

  20. Payne-Pólya-Weinberger type inequality for eigenvalues of sub-Laplacian in the Engel group%Engel群上sub-Laplace算子特征值的Payne-Pólya-Weinberger不等式

    Institute of Scientific and Technical Information of China (English)

    薛晶晶

    2013-01-01

    为得到Engel群上的Payne-Polya-Weinberger不等式,采用Rayleigh-Ritz原理对Engel群上的sub-Laplace算子进行计算,得到了Engel群上sub-Laplace算子△E=X21+X22=∑X2i特征值的Payne-Polya-Weinberger不等式λm+1-λm≤2/m(m∑i=1λi),其中X1,X2是Engel群上的左不变向量场.%To get a Payne-Pólya-Weinberger type inequality on the Engel group,Rayleigh-Ritz principle is used to calculate the sub-Laplace operator of the Engel group and finally establish the Payne-PólyaWeinberger type inequalityλm+1-λm ≤ 2m∑i=1λifor adjacent eigenvalues on sub-Laplace operator △E=X23+X22=2∑i=1X2i,which X1,X2 be the left-invariant vector fields in the Engel group.

  1. Fast and reliable interrogation of USFBG sensors based on MG-Y laser discrete wavelength channels

    Science.gov (United States)

    Rohollahnejad, Jalal; Xia, Li; Cheng, Rui; Ran, Yanli; Su, Lei

    2017-01-01

    In this letter, we propose to use discrete wavelength channels of a single chip MG-Y laser to interrogate an ultra-short fiber Bragg grating with a wide Gaussian spectrum. The broadband Gaussian spectrum of USFBG is sampled by the wavelength channels of MG-Y laser, through which the center of the spectrum. The measurement inherits the important features of a common tunable laser interrogation technique, namely its high flexibility, natural insensitivity to intensity variations relative to common intensity-based approaches. While for traditional tunable laser methods, it requires to sweep the whole spectrum to obtain the center wavelength of the spectrum, for the proposed scheme, just a few discrete wavelength channels of laser are needed to be acquired, which leads to significant improvements of the efficiency and measurement speed. This reliable and low cost concept could offer the good foundation for USFBGs future applications in large scale distributed measurements, especially in time domain multiplexing scheme.

  2. “HONRAR PAI E MÃE”: A INTERTEXTUALIDADE NUM ARTIGO DE OPINIÃO DE LYA LUFT / "HONOR FATHER AND MOTHER": THE INTERTEXTUALITY IN AN ARTICLE OF VIEW OF LYA LUFT

    OpenAIRE

    Sousa, Valdulce Ribeiro Cruz; Universidade Federal do Piauí-UFPI; Magalhães Neto, Pedro Rodrigues

    2014-01-01

    O objetivo deste artigo é analisar as marcas intertextuais, à luz da Linguística de Texto, na construção do artigo de opinião  Honrar Pai e Mãe, da escritora Lya Luft. Para tanto, toma-se como fundamento a concepção de “intertextualidade restrita” de Genette (1982 apud KOCH ET AL, 2007), que se define pelas relações de co-presença entre textos. Os resultados da análise permitem a constatação de marcas efetivas de vários textos na construção dos sentidos do referido artigo de opinião, indiciad...

  3. Effects of spin-orbit coupling on laser cooling of BeI and MgI

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Mingjie, E-mail: wanmingjie1983@sina.com; Huang, Duohui; Shao, Juxiang; Li, Yuanyuan [Computational Physics Key Laboratory of Sichuan Province, Yibin University, Yibin 644007 (China); Yu, You [College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu 610225 (China); Li, Song [College of Physical Science and Technology, Yangtze University, Jingzhou 434023 (China)

    2015-10-28

    We present the ab initio study of spin-orbit coupling effects on laser cooling of BeI and MgI molecules. Potential energy curves for the X{sup 2}Σ{sup +}{sub 1/2}, A{sup 2}Π{sub 1/2,3/2}, and 2{sup 2}Π{sub 3/2,1/2} states are calculated using multi-reference configuration interaction method plus Davidson corrections. Spectroscopic parameters of BeI and MgI are in excellent agreement with available experimental and theoretical values. The A{sup 2}Π{sub 3/2} state of MgI is a repulsive state. It is an unsuitable scheme for the A{sup 2}Π{sub 3/2}(υ′)← X{sup 2}Σ{sup +}{sub 1/2} (υ″) transition for laser cooling of MgI. Highly diagonally distributed Franck-Condon factors f{sub 00} for the A{sup 2}Π{sub 1/2,3/2} (υ′ = 0) ← X{sup 2}Σ{sup +}{sub 1/2} (υ″ = 0) transitions and suitable radiative lifetimes τ for the A{sup 2}Π{sub 1/2,3/2} (υ′ = 0) of BeI and MgI are obtained. Three laser wavelength drives are required for the A{sup 2}Π{sub 1/2,3/2}(υ′)←X{sup 2}Σ{sup +}{sub 1/2} (υ″) transitions of BeI and MgI. The proposed cooling wavelengths of BeI and MgI are both in the violet region. The results imply the feasibility of laser cooling of BeI and MgI, and that laser cooling of BeI is more possible.

  4. Effects of spin-orbit coupling on laser cooling of BeI and MgI.

    Science.gov (United States)

    Wan, Mingjie; Huang, Duohui; Shao, Juxiang; Yu, You; Li, Song; Li, Yuanyuan

    2015-10-28

    We present the ab initio study of spin-orbit coupling effects on laser cooling of BeI and MgI molecules. Potential energy curves for the X(2)Σ(+)(1/2), A(2)Π(1/2,3/2), and 2(2)Π(3/2,1/2) states are calculated using multi-reference configuration interaction method plus Davidson corrections. Spectroscopic parameters of BeI and MgI are in excellent agreement with available experimental and theoretical values. The A(2)Π(3/2) state of MgI is a repulsive state. It is an unsuitable scheme for the A(2)Π(3/2)(υ')← X(2)Σ(+)(1/2) (υ″) transition for laser cooling of MgI. Highly diagonally distributed Franck-Condon factors f00 for the A(2)Π(1/2,3/2) (υ' = 0) ← X(2)Σ(+)(1/2) (υ″ = 0) transitions and suitable radiative lifetimes τ for the A(2)Π(1/2,3/2) (υ' = 0) of BeI and MgI are obtained. Three laser wavelength drives are required for the A(2)Π(1/2,3/2)(υ')←X(2)Σ(+)(1/2) (υ″) transitions of BeI and MgI. The proposed cooling wavelengths of BeI and MgI are both in the violet region. The results imply the feasibility of laser cooling of BeI and MgI, and that laser cooling of BeI is more possible.

  5. Mechanical Properties of Mg-Gd and Mg-Y Solid Solutions

    Science.gov (United States)

    Kula, Anna; Jia, Xiaohui; Mishra, Raj K.; Niewczas, Marek

    2016-12-01

    The mechanical properties of Mg-Gd and Mg-Y solid solutions have been studied under uniaxial tension and compression between 4 K and 298 K (-269 °C and 25 °C). The results reveal that Mg-Gd alloys exhibit higher strength and ductility under tension and compression attributed to the more effective solid solution strengthening and grain-boundary strengthening effects. Profuse twinning has been observed under compression, resulting in a material texture with strong dominance of basal component parallel to compression axis. Under tension, twining is less active and the texture evolution is controlled mostly by slip. The alloys exhibit pronounced yield stress asymmetry and significantly different work-hardening behavior under tension and compression. Increasing of Gd and/or Y concentration leads to the reduction of the tension-compression asymmetry due to the weakening of the recrystallization texture and more balanced twinning and slip activity during plastic deformation. The results suggest that under compression of Mg-Y alloys slip is more active than twinning in comparison to Mg-Gd alloys.

  6. A MGy radiation-hardened sensor instrumentation link for nuclear reactor monitoring and remote handling

    Energy Technology Data Exchange (ETDEWEB)

    Verbeeck, Jens; Cao, Ying [KU Leuven - KUL, Div. LRD-MAGyICS, Kasteelpark Arenberg 10, 3001 Heverlee (Belgium); Van Uffelen, Marco; Mont Casellas, Laura; Damiani, Carlo; Morales, Emilio Ruiz; Santana, Roberto Ranz [Fusion for Energy - F4E, c/Josep,n deg. 2, Torres Diagonal Litoral, Ed. B3, 08019 Barcelona (Spain); Meek, Richard; Haist, Bernhard [Oxford Technologies Ltd. OTL, 7 Nuffield Way, Abingdon OX14 1RL (United Kingdom); De Cock, Wouter; Vermeeren, Ludo [SCK-CEN, Boeretang 200, 2400 Mol (Belgium); Steyaert, Michiel [KU Leuven, ESAT-MICAS, KasteelparkArenberg 10, 3001 Heverlee (Belgium); Leroux, Paul [KU Leuven, ESAT-MICAS, KasteelparkArenberg 10, 3001 Heverlee (Belgium)

    2015-07-01

    Decommissioning, dismantling and remote handling applications in nuclear facilities all require robotic solutions that are able to survive in radiation environments. Recently raised safety, radiation hardness and cost efficiency demands from both the nuclear regulatory and the society impose severe challenges in traditional methods. For example, in case of the dismantling of the Fukushima sites, solutions that survive accumulated doses higher than 1 MGy are mandatory. To allow remote operation of these tools in nuclear environments, electronics were used to be shielded with several centimeters of lead or even completely banned in these solutions. However, shielding electronics always leads to bulky and heavy solutions, which reduces the flexibility of robotic tools. It also requires longer repair time and produces extra waste further in a dismantling or decommissioning cycle. In addition, often in current reactor designs, due to size restrictions and the need to inspect very tight areas there are limitations to the use of shielding. A MGy radiation-hardened sensor instrumentation link developed by MAGyICS provides a solution to build a flexible, easy removable and small I and C module with MGy radiation tolerance without any shielding. Hereby it removes all these pains to implement electronics in robotic tools. The demonstrated solution in this poster is developed for ITER Remote Handling equipments operating in high radiation environments (>1 MGy) in and around the Tokamak. In order to obtain adequately accurate instrumentation and control information, as well as to ease the umbilical management, there is a need of front-end electronics that will have to be located close to those actuators and sensors on the remote handling tool. In particular, for diverter remote handling, it is estimated that these components will face gamma radiation up to 300 Gy/h (in-vessel) and a total dose of 1 MGy. The radiation-hardened sensor instrumentation link presented here, consists

  7. Boosting Lya and HeII 1640A Line Fluxes from Pop III Galaxies: Stochastic IMF Sampling and Departures from Case-B

    CERN Document Server

    Mas-Ribas, Lluís; Forero-Romero, Jaime E

    2016-01-01

    We revisit calculations of nebular hydrogen Lya and HeII 1640A line strengths for population III galaxies, undergoing continuous and bursts of star formation. We focus on initial mass functions (IMFs) motivated by recent theoretical studies, which generally span a lower range of stellar masses than earlier works. We also account for case-B departures and the stochastic sampling of the IMF. In agreement with previous works, we find that departures from case-B can enhance the Lya flux by a factor of a few, but we argue that this enhancement is driven mainly by collisional excitation and ionization, and not due to photoionization from the n = 2 state of atomic hydrogen. The increased sensitivity of the Lya flux to the high-energy end of the galaxy spectrum makes it more subject to stochastic sampling of the IMF. The latter introduces a dispersion in the predicted nebular line fluxes around the deterministic value by as much as a factor of ~4. In contrast, the stochastic sampling of the IMF has less impact on the...

  8. Resolving the optical emission lines of Lya blob 'B1' at z=2.38: another hidden quasar

    CERN Document Server

    Overzier, R A; Dijkstra, M; Hatch, N A; Lehnert, M D; Villar-Martín, M; Wilman, R J; Zirm, A W

    2013-01-01

    We have used the SINFONI near-infrared integral field unit on the VLT to resolve the optical emission line structure of one of the brightest (L~1e44 erg/s) and nearest (z=2.38) of all Lya blobs (LABs). The target, known in the literature as object 'B1' (Francis et al. 1996), lies at a redshift where the main optical emission lines are accessible in the observed near-infrared. We detect luminous [OIII]4959,5007A and Ha emission with a spatial extent of at least 32x40 kpc (4"x5"). The dominant optical emission line component shows relatively broad lines (600-800 km/s, FWHM) and line ratios consistent with AGN-photoionization. The new evidence for AGN photoionization, combined with previously detected CIV and luminous, warm infrared emission, suggest that B1 is the site of a hidden quasar. This is confirmed by the fact that [OII] is relatively weak compared to [OIII] (extinction-corrected [OIII]/[OII] of about 3.8), which is indicative of a high, Seyfert-like ionization parameter. From the [OIII] luminosity we i...

  9. Study on the early surface films formed on Mg-Y molten alloy in different atmospheres

    Directory of Open Access Journals (Sweden)

    A.R. Mirak

    2015-09-01

    Full Text Available In the present study, the non-isothermal early stages of surface oxidation of liquid Mg-1%Y alloy during casting were studied under UPH argon, dry air, and air mixed with protective fluorine-bearing gases. The chemistry and morphology of the surface films were characterized by SEM and EDX analyses. The results indicate a layer of smooth and tightly coherent oxidation film composed of MgO and Y2O3 formed on the molten Mg-Y alloy surface with 40–60 nm thickness under dry air. A dendritic/cellular microstructure is clearly visible with Y-rich second phases gathered in surface of the melt and precipitated along the grain/cell boundaries under all gas conditions. Under fluorine-bearing gas mixtures, the surface film was a mixed oxide and fluoride and more even; a flat and folded morphology can be seen under SF6 with oxide as dominated phase and under 1, 1, 1, 2-tetra-fluoroethane, a smooth and compact surface film uniformly covering the inner surface of the bubble with equal oxide and fluoride thickness, which results in a film without any major defects. MgF2 phase appears to be the key characteristic of a good protective film.

  10. Discovery of a Damped Lya Absorber at z = 3.3 along a galaxy sight-line in the SSA22 field

    CERN Document Server

    Mawatari, K; Kousai, K; Hayashino, T; Cooke, R; Prochaska, J X; Yamada, T; Matsuda, Y

    2015-01-01

    Using galaxies as background light sources to map the Lya absorption lines is a novel approach to study Damped Lya Absorbers (DLAs). We report the discovery of an intervening z = 3.335 +- 0.007 DLA along a galaxy sight-line identified among 80 Lyman Break Galaxy (LBG) spectra obtained with our VLT/VIMOS survey in the SSA22 field. The measured DLA neutral hydrogen (HI) column density is log (NHI/cm^{-2}) = 21.68 +- 0.17. The DLA covering fraction over the extended background LBG is > 70 % (2 sigma), yielding a conservative constraint on the DLA area as > 1 kpc^2. Our search for a counterpart galaxy hosting this DLA concludes that there is no counterpart galaxy with star formation rate (SFR) larger than a few Msun yr^{-1}, ruling out an unobscured violent star formation in the DLA gas cloud. We also rule out the possibility that the host galaxy of the DLA is a passive galaxy with Mstar > 5 x 10^{10} Msun or a heavily dust-obscured galaxy with E(B-V) > 2. The DLA may coincide in a large-scale overdensity of the ...

  11. Thermoluminescence (TL) Analysis and Fading Studies of Naturally Occurring Salt Irradiated by 500 mGy Gamma Rays

    Science.gov (United States)

    Tiwari, Ramesh Chandra; Pau, Kham Suan

    2011-10-01

    The aim of the present study was to investigate the potential of the naturally occurring salt for the dosimetry purposes, using TL. The fine powder samples (20 mg) were irradiated by γ- rays from 500 mGy to 2500 mGy by using Theratron-780C Cobalt-60 source, however, this paper discusses about 500 mGy only. The TL glow curve peak parameters were studied by using Chen's peak shape equation. TL glow curves were compared with fitted curves using glow curve deconvolution (GCD) method by using Kitis expression. The kinetic parameter values (E, b and s) so calculated, are in good agreement with those available in literature. The calculated energy values were also verified by using various heating rate (VHR) method. χ2 test and figure of merit (FOM) calculation was done to accept the goodness of fit between the curves. Fading studies of the sample showed a good fitting between the curves. The analysis suggests that natural salt should be considered for dosimetry purposes.

  12. Likota lya bankoya

    NARCIS (Netherlands)

    Shimunika, Johasaphat Malasha; Binsbergen, Wim van

    1988-01-01

    This text of "The history of the Nkoya people" keeps as closely as possible to the original manuscript as written in the 1950s-1960s. (An English translation is included as part 3 in Wim van Binsbergen's 'Tears of rain: ethnicity and history in central western Zambia', published in London in 1992 by

  13. Ahi Community as an Educational Institution and “Marks of Ahi Community Culture on Today’s Bursa Craftsman” by Hülya Taş / Kitap Tanıtım ve Değerlendirme: Bir Eğitim Kurumu Olarak Ahilik ve Hülya Taş’ın “Günümüz Bursa Esnafında Ahilik Kültüründen İzler”Adlı Eseri

    Directory of Open Access Journals (Sweden)

    Sıddık BAKIR

    2014-03-01

    Full Text Available This article is about Ahi community comprising of moral, religious, social and cultural values; the relationship between Ahi community and education; the presentation of the study named“Marks of Ahi Community on Today’s Bursa Craftsman”written by Hülya TAŞ in essence. In addition, the article gives publicity to the autobiography of Hülya TAŞ who has done successful studies aboutTurkish folklore and Ahi community and her academic studies. Bu makale esas itibariyle ahlaki, dinî, sosyal ve kültürel değerler bütünü olan ahilik teşkilatını, ahilik teşkilatının eğitim ile ilişkisini ve Hülya TAŞ tarafından hazırlanan “Günümüz Bursa Esnafında Ahilik Kültüründen İzler” adlı eserin tanıtımını konu almaktadır. Makalede ayrıca Türk halk bilimi ve ahilikle ilgili başarılı çalışmalar yapan Hülya TAŞ’ın öz geçmişine ve akademik çalışmalarına da yer verilmektedir.

  14. Design of a MGy radiation tolerant resolver-to-digital convertor IC for remotely operated maintenance in harsh environments

    Energy Technology Data Exchange (ETDEWEB)

    Leroux, Paul, E-mail: paul.leroux@kuleuven.be [KU Leuven, Dept. of Electrical Engineering (ESAT), AdvISe, Kleinhoefstraat 4, 2440 Geel (Belgium); Van Koeckhoven, Wesley; Verbeeck, Jens [KU Leuven, Dept. of Electrical Engineering (ESAT), AdvISe, Kleinhoefstraat 4, 2440 Geel (Belgium); Van Uffelen, Marco; Esqué, Salvador; Ranz, Roberto; Damiani, Carlo [Fusion for Energy, Torres Diagonal Litoral B3, Josep Pla 2, 08019 Barcelona (Spain); Hamilton, David [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul-lez-Durance (France)

    2014-10-15

    During future ITER maintenance operations, sensors and their embarked electronics will be exposed to a hostile and radioactive environment. This paper presents the design of a MGy radiation tolerant 16 bit resolver-to-digital converter (RDC) in 130 nm CMOS technology. The RDC features a Type II digital tracking loop, able to track resolvers with speeds up to 300 rps, and excitation frequencies up to 4 kHz. The RDC uses two integrated ΔΣ-analog-to-digital converters (ADCs) to digitize the resolver outputs. The 16 bit, 10 kHz ADCs utilize a correlated double sampling technique to remove radiation induced offset and 1/f-noise. The front-end features a static angular resolution of 16 bits (4.2 arcsec{sub rms}) and a resolution of 10 bits (6 arcmin{sub rms}) at a rotor speed of 100 rps. The circuit has a simulated radiation tolerance exceeding 1 MGy. It has the ability to operate under temperatures up to 125 °C, and to allow multiplexing with signals from other conventional sensors for compact, robust read-out architectures.

  15. Analysis of hematopoiesis in mice irradiated with 500 mGy of X rays at different stages of development

    Energy Technology Data Exchange (ETDEWEB)

    Grande, T.; Bueren, J.A. [U. de Biologia Molecular y Celular, Madrid (Spain)

    1995-09-01

    We have investigated whether a relatively low dose of 500 mGy of X rays given as a single acute irradiation at different stages of pre-and postnatal development induces significant changes in the content of femoral hematopoietic progenitores during a 1-year period after irradiation. Data obtained show that, in the case of 4-day-old embryos as well as in 2-day, 8-day and 12-week-old mice, this dose is below the threshold capable of inducing a long-term impairment of hematopoiesis in the mouse. Nevertheless, in mice irradiated at the 13th or the 17th day postconception, a hematopoietic dysfunction consisting of a significant reduction in the proportion of femoral granulocyte-macrophage colony-forming units (CFU-GM) was manifested 1 year after irradiation. Our study confirms that, for most stages of development in the mouse, a single acute X irradiation of 500 mGy is below the threshold dose capable of inducing deterministic effects in the mouse hematopoietic system, although it reveals the induction of a significant impairment in the CFU-GM population when irradiation is given at the late stages of embryonic development. 24 refs., 4 figs.

  16. Improved electrochemical hydrogen storage properties of Mg-Y thin films as a function of substrate temperature

    Institute of Scientific and Technical Information of China (English)

    Yanyan Wang; Gongbiao Xin; Chongyun Wang; Huiyu Li; Wei Li; Jie Zheng; Xingguo Li

    2014-01-01

    Pd-capped Mg78 Y22 thin films have been prepared by direct current magnetron co-sputtering system at different substrate temperatures and their electrochemical hydrogen storage properties have been investigated. It is found that rising substrate temperature to 60◦C can coarsen the surface of thin film, thus facilitating the diffusion of hydrogen atoms and then enhancing its discharge capacity to ∼1725 mAh·g-1 . Simultaneously, the cyclic stability is effectively improved due to the increased adhesion force between film and substrate as a function of temperature. In addition, the specimen exhibits a very long and flat discharge plateau at about-0.67 V, at which nearly 60%of capacity is maintained. The property is favorable for the application in metal hydride/nickel secondary batteries. The results indicate that rising optimal substrate temperature has a beneficial effect on the electrochemical hydrogen storage of Mg-Y thin films.

  17. Regioselective Addition of Silyl Enolates to α,β-Unsaturated Aldehyde and its Acetal Catalyzed by MgI2 Etherate

    Institute of Scientific and Technical Information of China (English)

    Xing Xian ZHANG; Wei Dong Z. LI

    2003-01-01

    Regioselective addition reactions of silyl enolates to α,β -unsaturated aldehyde and its acetal catalyzed by MgI2 etherate give aldol adducts (1, 2-addition) preferentially over Michael adducts (1, 4-addition). This unique regioselectivity is distinctly different with other Lewis acidic promoters and may be attributed to the high oxyphilicity of IMg+.

  18. Optimization of MGI in JET using the TOKES code and mitigation of RE damage for the first wall

    Energy Technology Data Exchange (ETDEWEB)

    Pestchanyi, S., E-mail: serguei.pestchanyi@kit.edu [Karlsruhe Institute of Technology, 76344, Karlsruhe (Germany); Boboc, A. [EURATOM/CCFE Fusion Association, Culham Science Centre Abingdon, Oxfordshire OX14 3DB (United Kingdom); Bazylev, B.; Landman, I. [Karlsruhe Institute of Technology, 76344, Karlsruhe (Germany)

    2014-10-15

    Highlights: •We simulated disruption mitigation using massive noble gas injection with the TOKES code. •The results of these simulations have been verified by comparison with JET experiments. •We have found that the amount of gas for triggering the thermal quench can be reduced 40 times. •We propose a special sacrificial diaphragm for mitigation of the wall damage with runaway electrons (RE). •The diaphragm erosion with RE beam has been roughly estimated. -- Abstract: Simulations of massive gas injection (MGI) into the JET plasma using noble gas (NG) have been performed using the TOKES code. The results of these simulations have been verified by comparison with JET experiment for disruption control. Further simulations performed showed that the amount of NG for triggering the thermal quench can be reduced 40 times comparing with the JET experiment. Such small amount of injected NG should generate runaway electrons (RE) with rather large probability. For mitigation of the wall damage with these RE, a special sacrificial diaphragm consisting of several W ‘nails’ with a characteristic thickness of 2 cm has been proposed. The diaphragm erosion with RE beam has been roughly estimated from above as less than 0.5 cm per disruption. Taking into account the plasma shielding may decrease erosion ∼10 times.

  19. Improved performance of Mg-Y alloy thin film switchable mirrors after coating with a superhydrophobic surface

    Science.gov (United States)

    La, Mao; Zhou, Huaijuan; Li, Ning; Xin, Yunchuan; Sha, Ren; Bao, Shanhu; Jin, Ping

    2017-05-01

    The magnesium based switchable mirrors can reversibly change their optical properties between the transparent and the reflective state as a result of hydrogenation and dehydrogenation. These films can potentially be applied as new energy-saving windows, by controlling the transmittance of solar radiation through the regulation of their reflective state. In this study, magnesium-yttrium (Mg-Y) alloy thin films were prepared using a DC magnetron sputtering method. However, the luminous transmittance in the transparent state and the switching durability of switchable mirrors are too poor to satisfy practical demands. In order to improve the films switching durability, luminous transmittance and the surface functionalization, polytetrafluoroethylene (PTFE) was coated with thermal vacuum deposition for use as the top layer of Mg-Y/Pd switchable mirrors. The PTFE layer had a porous network structure and exhibited a superhydrophobic surface with a water contact angle of approximately 152°. By characterization, PTFE thin films shows the excellent protection role against the oxidization of Mg, the switching durability of the films were improved 3 times, and also shows the antireflection role the luminous transmission of films was enhanced by 7% through the top covered with PTFE.

  20. A single-phased tunable emission phosphor MgY2Si3O10: Eu(3+), Bi(3+) with efficient energy transfer for white LEDs.

    Science.gov (United States)

    Zhou, Hongpeng; Jin, Ye; Jiang, Mingsong; Wang, Qingping; Jiang, Xingxing

    2015-01-21

    A novel single-phased tunable emitting phosphor MgY2Si3O10: Bi(3+), Eu(3+) has been synthesized by a conventional high temperature solid-state method. X-ray diffraction (XRD), photoluminescence emission and excitation spectra were utilized to characterize the as-synthesized samples. Under UV-light pumping, MgY2Si3O10: Bi(3+) showed characteristic blue emission corresponding to the (3)P1→(1)S0 transition of Bi(3+) ions, and MgY2Si3O10: Eu(3+) showed characteristic red emission corresponding to the (5)D0→(7)FJ (J = 1, 2, 3, 4) transition of Eu(3+) ions. Spectra indicate that Bi(3+) ions occupy two nonequivalent sites in the MgY2Si3O10 matrix, namely, Bi(3+)(i) and Bi(3+)(ii). The two sites (Bi(3+)(i) and Bi(3+)(ii)) exhibit broad emission peaks at 411 nm and 490 nm, respectively. Efficient energy transfer between these two Bi(3+) sites has been proven using the spectra. The spectral overlap between the emission spectrum of Bi(3+) and the excitation spectrum of Eu(3+) allows for resonance-type energy transfer to occur from Bi(3+) to Eu(3+). The efficient energy transfer from Bi(3+) to Eu(3+)via a dipole-quadrupole interaction mechanism is significantly demonstrated by comparing experimental data with theoretical calculations. According to the concentration quenching-method, the critical distance of energy transfer from Bi(3+) to Eu(3+) is calculated to be 13.2 Å. As it is a new phosphor, CIE coordinates and CCT temperature, in addition to efficient energy transfer have been also investigated in detail. White light emission for MgY2Si3O10: n Bi(3+), m Eu(3+) can be realized through controlling the concentrations of Bi(3+) and Eu(3+). All of the results indicate that MgY2Si3O10: n Bi(3+), m Eu(3+) is a potential phosphor for white light UV-LEDs.

  1. Synthesis and characterization of LiMgyMn2–yO4 cathode materials by a modified Pechini process for lithium batteries

    Indian Academy of Sciences (India)

    A Subramania; N Angayarkanni; A R Sathiya Priya; R Gangadharan; T Vasudevan

    2005-12-01

    Cubic spinels of composition, LiMgyMn2–yO4, with = 0.0, 0.05, 0.1, 0.15 and 0.2, were synthesized by a modified Pechini process using polyethylene glycol and citric acid. The phase formation and/or crystallization of the precursors were studied by thermal analysis. Products were characterized by X-ray diffraction and SEM analysis. Coin cells were fabricated with lithium as the anode and LiMgyMn2–yO4 as the cathode in an electrolyte of 1 M LiPF6 in a 1 : 1 (v/v) mixture of EC and DEC. The charge–discharge studies were performed and the results were compared with materials prepared by a solid state thermal method.

  2. Efficiency enhancement in dye sensitized solar cells using gel polymer electrolytes based on a tetrahexylammonium iodide and MgI2 binary iodide system.

    Science.gov (United States)

    Bandara, T M W J; Dissanayake, M A K L; Jayasundara, W J M J S R; Albinsson, I; Mellander, B-E

    2012-06-28

    Quasi-solid-state dye-sensitized solar cells have drawn the attention of scientists and technologists as a potential candidate to supplement future energy needs. The conduction of iodide ions in quasi-solid-state polymer electrolytes and the performance of dye sensitized solar cells containing such electrolytes can be enhanced by incorporating iodides having appropriate cations. Gel-type electrolytes, based on PAN host polymers and mixture of salts tetrahexylammonium iodide (Hex4N(+)I(-)) and MgI2, were prepared by incorporating ethylene carbonate and propylene carbonate as plasticizers. The salt composition in the binary mixture was varied in order to optimize the performance of solar cells. The electrolyte containing 120% Hex4N(+)I(-) with respect to weight of PAN and without MgI2 showed the highest conductivity out of the compositions studied, 2.5 × 10(-3) S cm(-1) at 25 °C, and a glass transition at -102.4 °C. However, the electrolyte containing 100% Hex4N(+)I(-) and 20% MgI2 showed the best solar cell performance highlighting the influence of the cation on the performance of the cell. The predominantly ionic behaviour of the electrolytes was established from the dc polarization data and all the electrolytes exhibit iodide ion transport. Seven different solar cells were fabricated employing different electrolyte compositions. The best cell using the electrolyte with 100% Hex4N(+)I(-) and 20% MgI2 with respect to PAN weight showed 3.5% energy conversion efficiency and 8.6 mA cm(-2) short circuit current density.

  3. Effect of Porous Structure on the Magnetic Properties of NixMgyZn1-x-yFe2O4Magnetic Materials

    Institute of Scientific and Technical Information of China (English)

    QI Xin; ZHOU Xin; SHU Di; ZHAO Jing-Jing; WANG Wei; CHEN Juan

    2011-01-01

    We deal with the preparation of NiMgZnFeⅢ-SO4 layered double hydroxides (LDHs) with the layered precursor method and introduce excessive ZnO into the NiMgZnFeⅢ-SO4 LDHs to produce NixMgyZn1-x-yFe2O4 ferrites that contain massive ZnO. Then the NixMgyZn1-x-yFe2O4 ferrites are treated with NaOH solution to remove ZnO to produce the porous NixMgyZn1-x-yFe2O4 magnetic material: when y = 0, porous NiZnFe2O4 ferrite magnetic materials are obtained; when y≠0, porous NiMgZnFezO4 ferrite magnetic materials are obtained. From analyses of these two ferrites, their pore-forming mechanism and comparison of their properties before and after they undergo the alkali treatment, we find that after being treated by the NaOH solution, NiZnFe2O4/ NiMgZnFe2O4 have better uniform-structure pores, which will greatly expand their pore volume, widen their application scope and improve their magnetic properties.%We deal with the preparation of NiMgZnFeⅢ-SO4 layered double hydroxides (LDHs) with the layered precursor method and introduce excessive ZnO into the NiMgZnFeⅢ-SO4 LDHs to produce NixMgyZn1-x-yFe2O4 ferrites that contain massive ZnO.Then the NixMgyZn1-x-yFe2O4 ferrites are treated with NaOH solution to remove ZnO to produce the porous NixMgyZn1-x-yFe2O4 magnetic material:when y =0,porous NiZnFe2O4 ferrite magnetic materials are obtained;when y ≠ 0,porous NiMgZnFe2O4 ferrite magnetic materials are obtained.From analyses of these two ferrites,their pore-forming mechanism and comparison of their properties before and after they undergo the alkali treatment,we find that after being treated by the NaOH solution,NiZnFe2O4/NiMgZnFe2O4 have better uniform-structure pores,which will greatly expand their pore volume,widen their application scope and improve their magnetic properties.Owing to their fine resistance,high Curie temperature,low temperature coefficient and good high-frequency performance,nickel-zinc ferrite materials have been widely used in high-frequency magnetic

  4. Life performance of an EPR-insulated power cable exposed in service beyond 3 MGy in high-level radiation area

    Science.gov (United States)

    Grüb, R.; Langeset, B.; Maier, P.; Schönbacher, H.

    1983-09-01

    Mechanical and electrical test results are reported for a power cable that has been installed for three and a half years in a high-level radiation area at the European Organization for Nuclear Research (CERN). The degradation of selected mechanical properties as a function of absorbed dose is compared with results of a short-term irradiation in a nuclear reactor. The tensile test specimens have been taken from the ethylene propylene rubber insulation and the polyvinyl chloride sheath material of the cable after exposure in service. For the measurement of breakdown voltage, short portions of insulated cable have been used. The aim of this work was to verify that the combined functional and environmental stress factors did not lead to more damage of the cable than was expected from the value of absorbed dose, and eventually to predict more precisely the service life of similar cables. The ratios of doses after service and short-term irradiation at 50% reduction of elongation at break were about 0.5 for the insulation and 1.0 for the sheath material at a dose of about 1 MGy. However, the breakdown voltage did not show any significant variation in the dose range covered up to 3.6 MGy. Therefore, a safe lower dose limit may readily be derived from accelerated tests, but the margin until failure in service remains to be determined.

  5. Total body 100-mGy X-irradiation does not induce Alzheimer's disease-like pathogenesis or memory impairment in mice.

    Science.gov (United States)

    Wang, Bing; Tanaka, Kaoru; Ji, Bin; Ono, Maiko; Fang, Yaqun; Ninomiya, Yasuharu; Maruyama, Kouichi; Izumi-Nakajima, Nakako; Begum, Nasrin; Higuchi, Makoto; Fujimori, Akira; Uehara, Yoshihiko; Nakajima, Tetsuo; Suhara, Tetsuya; Ono, Tetsuya; Nenoi, Mitsuru

    2014-01-01

    The cause and progression of Alzheimer's disease (AD) are poorly understood. Possible cognitive and behavioral consequences induced by low-dose radiation are important because humans are exposed to ionizing radiation from various sources. Early transcriptional response in murine brain to low-dose X-rays (100 mGy) has been reported, suggesting alterations of molecular networks and pathways associated with cognitive functions, advanced aging and AD. To investigate acute and late transcriptional, pathological and cognitive consequences of low-dose radiation, we applied an acute dose of 100-mGy total body irradiation (TBI) with X-rays to C57BL/6J Jms mice. We collected hippocampi and analyzed expression of 84 AD-related genes. Mouse learning ability and memory were assessed with the Morris water maze test. We performed in vivo PET scans with (11)C-PIB, a radiolabeled ligand for amyloid imaging, to detect fibrillary amyloid beta peptide (Aβ) accumulation, and examined characteristic AD pathologies with immunohistochemical staining of amyloid precursor protein (APP), Aβ, tau and phosphorylated tau (p-tau). mRNA studies showed significant downregulation of only two of 84 AD-related genes, Apbb1 and Lrp1, at 4 h after irradiation, and of only one gene, Il1α, at 1 year after irradiation. Spatial learning ability and memory were not significantly affected at 1 or 2 years after irradiation. No induction of amyloid fibrillogenesis or changes in APP, Aβ, tau, or p-tau expression was detected at 4 months or 2 years after irradiation. TBI induced early or late transcriptional alteration in only a few AD-related genes but did not significantly affect spatial learning, memory or AD-like pathological change in mice.

  6. Interband optical absorption in wurtzite MgxZn1-xO/ZnO/MgyZn1-yO asymmetric quantum wells

    Science.gov (United States)

    Gu, Z.; Zhu, Z. N.; Wang, M. M.; Wang, Y. Q.; Wang, M. S.; Qu, Y.; Ban, S. L.

    2017-02-01

    Based on Fermi golden rule, the optical absorption induced by interband transition of electrons and holes in wurtzite MgxZn1-xO/ZnO/MgyZn1-yO asymmetric quantum wells at room temperature has been discussed. The built-in electric field (BEF) and Poisson potential are considered to calculate the eigenstates and eigenenergies of electrons and holes. The interband optical absorption coefficients (IOACs) influenced by ternary mixed crystal and size effects as functions of incident photon wavelengths are presented. The results indicate that increasing Mg component in left barrier can enhance the BEF to enforce electrons (holes) close to the left (right) interface, so as to reduce the overlapping of their wave functions. Thus the IOAC peak decreases rapidly and presents a blue shift with the increment of Mg component x. Furthermore, the size effect on IOACs is also discussed. The absorption peak is more sensitive to the change of the well width than the left barrier size. The absorption peak reduces sharply and shows a red shift with the increase of the well width. Our results could provide guidance on experiments and device fabrication.

  7. Cleaning spectroscopic samples of stars in nearby dwarf galaxies: The use of the nIR MgI line to weed out Milky Way contaminants

    CERN Document Server

    Battaglia, Giuseppina

    2012-01-01

    Dwarf galaxies provide insights on the processes of star formation and chemical enrichment at the low end of the galaxy mass function, as well as on the clustering of dark matter on small scales. In studies of Local Group dwarf galaxies, spectroscopic samples of individual stars are used to derive the internal kinematics and abundance properties of these galaxies. It is therefore important to clean these samples from Milky Way stars, not related to the dwarf galaxy, since they can contaminate the analysis of the properties of these objects. Here we introduce a new diagnostic for separating Milky Way contaminant stars -- that mainly constitute of dwarf stars -- and red giant branch stars targeted in dwarf galaxies. As discriminator we use the trends in the equivalent width of the nIR MgI line at 8806.8 \\AA\\ as a function of the equivalent width of CaII triplet lines. This method is particularly useful for works dealing with multi-object intermediate resolution spectroscopy focusing in the region of the nIR CaI...

  8. The response of TL lithium fluoride detectors to 24 GeV/c protons for doses ranging up to 1 MGy

    CERN Document Server

    Obryk, B; Olko, P; Pajor, A; Glaser, M; Budzanowski, M; Bilski, P

    2010-01-01

    A new method of thermoluminescent (TL) measurement of radiation doses ranging from micrograys up to a megagray has been recently developed at IFJ. This method is based on a newly discovered behavior of LiF:Mg,Cu,P detectors at doses exceeding 1 kGy. Significant changes in their glow-curves are observed at higher doses; of special importance is occurrence of a new, well separated peak for doses above 50 kGy, thus these detectors can be used for measurements of doses at ultra-high dose range. In order to check the glow-curve features in the high dose region for different types of LiF:Mg,Cu,P and LiF:Mg,Ti detectors after irradiation with heavy charged particles, tests at the 24 GeV/c proton beam of IRRAD1 irradiation zone at the CERN Proton Synchrotron accelerator up to 1 MGy were performed. The occurrence of the high dose peak in the glow-curve of LiF:Mg,Cu,P detectors resulting from heavy particles irradiation was confirmed. Results of this investigation are presented in this paper. (C) 2010 Elsevier Ltd. All...

  9. KASAPOĞLU ÇENGEL, Hülya Kırgız Türkçesi Grameri Ses ve Şekil Bilgisi, Akçağ/700, Ankara, 2005, 424 s, ISBN 975-338-687-7.

    OpenAIRE

    KINACI, Cemile

    2007-01-01

    gözden geçirildi inde, Prof. Dr. Hülya Kasapo lu Çengel’in bu çalõ masõnõn ala- nõndaki ilk örneklerden biri oldu u görülür. Eser, Kõrgõz Türkçesinin ses ve e- kil bilgisini derli toplu ve ayrõntõlõ ekilde vermektedir. Kõrgõz Türkçesi Grameri sadece Türkoloji çevrelerinin de il; Kõrgõz Türkçesini ö renmek isteyenlerin de ba vuru kaynaklarõndan biri niteli indedir

  10. KASAPOĞLU ÇENGEL, Hülya Kırgız Türkçesi Grameri Ses ve Şekil Bilgisi, Akçağ/700, Ankara, 2005, 424 s, ISBN 975-338-687-7.

    OpenAIRE

    KINACI, Cemile

    2007-01-01

    gözden geçirildi inde, Prof. Dr. Hülya Kasapo lu Çengel’in bu çalõ masõnõn ala- nõndaki ilk örneklerden biri oldu u görülür. Eser, Kõrgõz Türkçesinin ses ve e- kil bilgisini derli toplu ve ayrõntõlõ ekilde vermektedir. Kõrgõz Türkçesi Grameri sadece Türkoloji çevrelerinin de il; Kõrgõz Türkçesini ö renmek isteyenlerin de ba vuru kaynaklarõndan biri niteli indedir

  11. Red emission enhancement in Ce3+/Mn2+ co-doping suited garnet host MgY2Al4SiO12 for tunable warm white LED

    Science.gov (United States)

    Pan, Zaifa; Chen, Jiacheng; Wu, Haiqin; Li, Weiqiang

    2017-10-01

    To enhance the red emission of YAG:Ce3+ system, co-doping a second activator is one of the attractive approaches and Mn2+ is a priority candidate for red emission. However, the doping of Mn2+ in YAG will result in the multi-occupancy in different crystallographic sites, due to the mismatch of crystal radius and charge. Thus, a suited aluminate silicate garnet phosphor host MgY2Al4SiO12 with ideal crystallographic sites for the co-doping of Ce3+ and Mn2+ ions, was adopted to be the host. The local coordination of Mn2+ ions, occupying only the dodecahedral Mg2+ sites in our suited garnet phosphor, was confirmed by XRD, XPS and photoluminescence results. A color tunable emission of the Ce3+/Mn2+ co-doping phosphor MgY2Al4SiO12 can be realized by combining the yellow emission (565 nm) originating from Ce3+ with the red emission (620 nm) from Mn2+, under 460 nm excitation. The energy transfer efficiency from Ce3+ to Mn2+ via adipole-quadrupole mechanism was demonstrated to be high and reach 79.7%, which is quite higher than 45% in YAG:Ce3+,Mn2+,Si4+. More importantly, the enhancement of red emission makes the emitting colors be able to be adjusted from yellow to orange-red, which would be beneficial to the colorpoint tuning of WLED. The excellent photoluminescence characterizes with high quantum yields (up to 89.0%) indicates that the designed MgY2Al4SiO12:Ce3+,Mn2+ phosphor is a good candidate to obtain warm white LED.

  12. Study of the intergranular coupling of Cu0.5Tl0.5Ba2Ca2-yMgyCu3O10-δ (y = 0, 0.5, 1.0 and 1.5) superconductors

    Science.gov (United States)

    Khurram, A. A.; Khan, Nawazish A.

    2006-06-01

    The intergranular properties of Cu0.5Tl0.5Ba2Ca2-yMgyCu3O10-δ superconductor have been studied by resistivity and AC magnetic susceptibility measurements. Magnesium substitution has been found to improve the interplane coupling in the unit cell of Cu0.5Tl0.5Ba2Ca2-yMgyCu3O10-δ, which in turn would enhance the intergranular coupling. The main objective of the present studies was to observe any possible role played by Mg doping in developing and enhancing the intergranular coupling and flux pinning properties of this compound. Any improvement to the intergrain coupling may be promoted by a change in the oxygen content in the final compound. Since the loss and/or intake of oxygen occurs at Ta>=350 °C, the post-annealing experiments were carried out at 500 °C for 3 h in air, nitrogen and oxygen atmospheres. It was observed from these studies that the oxygen contents decreased in all the samples after post-annealing in air, nitrogen and oxygen atmospheres. The most prominent effects in terms of enhanced superconductivity in the intergranular regions are observed in Mg-doped samples after post-annealing in air. The Mg-doped samples have shown enhanced granular connectivity, since the intergranular coupling peak observed in χ'' in AC susceptibility measurements is shifted to higher temperatures with the increase of Mg concentration. The enhanced intergranular coupling and flux pinning in magnesium-substituted samples is also observed in AC susceptibility measurements in external magnetic fields. The enhancement of intergranular coupling increases the transport critical current density of the samples.

  13. Microtexture evolution in Mg-Y and AZ31 Mg alloy during hot deformation%Mg-Y及AZ31镁合金高温变形过程中微观织构的演化

    Institute of Scientific and Technical Information of China (English)

    杨续跃; 张雷; 姜育培; 朱亚坤

    2011-01-01

    在温度为723 K、应变速度为3×10-3 s-1的条件下,对Mg-Y及AZ31镁合金挤压棒材进行单向压缩变形,利用OM、SEM和EBSD观察、分析Y对挤压棒材动态再结晶和微观织构的影响.结果表明:AZ31镁合金在真应变ε=0.2时发生明显的动态再结晶,在ε=0.5时,动态再结晶晶粒的体积分数高达80%以上;而Mg-Y合金在真应变ε=0.4时,动态再结晶体积分数尚不足10%,Y对镁合金动态再结晶有显著的阻碍作用;AZ31镁合金变形时,几乎所有晶粒的基面趋向于由变形前平行于压缩方向转至垂直于压缩方向,导致基面织构在ε=1.2时发生近90°的转动;Mg-Y合金则只有小部分晶粒发生转动,转动所形成的择优取向在动态再结晶后显著弱化,并导致取向分布更加随机;Y的添加可导致镁合金基面织构在动态再结晶后显著弱化.%The effects of Y on the dynamic recrystallization (DRX) and microtexture evolution of hot deformed Mg alloy were studied by optical, SEM and EBSD microscopy.For this purpose, AZ31 and Mg-Y alloy bars were compressed at strain rate of 3× 10-3 s-1 and at temperature of 723 K.The results show that DRX frequently takes place in AZ31 Mg alloy just after being compressed to strained ε=0.2 and the volume fraction of DRX grains is more than 80% after further being compressed to strained 0.5.Whereas alloying by Y retarded DRX, the fraction of DRX in Mg-Y alloy is less than 10%even at the strain of 0.4.In AZ31 Mg alloy, the alignment of the basal planes initially parallel to the compression direction is rotated gradually by compression and approaches perpendicular to the compression direction in high strain and the basal texture is rotated by about 90° at the strain of 1.2.But in Mg-Y alloy, only a few grains rotate to be perpendicular to the compression direction with increasing strain.The basal texture caused by the rotated grains is significantly weakened and the orientation distribution becomes more random

  14. 两类负顾客M/GI/1系统的统计平衡条件%Analysis on Stability Conditions for M/GI/1 Queueing Models with Negative Arrivals

    Institute of Scientific and Technical Information of China (English)

    朱翼隽; 唐祥金; 陈洋; 陈燕

    2006-01-01

    负顾客排队模型由于其灵活模拟各种复杂随机现象的广阔的应用前景,当前正越来越受到各类高性能通讯网络研究多方面的广泛关注.由于负顾客的抵消作用这类系统可以容许在顾客到达率大于服务率的情况下,进入平稳状态.本文用马尔可夫更新理论和Foster负偏移准则,研究了两类M/G1/1负顾客排队模型进入平稳状态的充要条件,首次得到了负顾客更新到达情况下,带负顾客抵消队列头部正顾客和队列尾部正顾客两种策略下的M/G1/1(FCFS)系统的统计平衡条件.当负顾客到达取更新过程的特例-泊松过程时,这一结果与Harrison&Pital(1996)中所得结果完全一致.%Recently queueing models with negative customers have been more and more brought to a widespread notice in the research field for various communication networks of high performance, due to their broad applying prospect to simulate many complicated stochastic phenomena with flexibility. Rely on the removal function of the negative customers such queueing system may enter its equilibrium state even when the ordinary arriving rate is great than its service rate.In this paper we study some sufficient & necessary conditions for two types of M/GI/1 queue with negative arrivals entering into their steady states by means of the Markov renewal theory and Foster's negative drift crierien. The stability conditions for M/GI/1-FCFS (First Come First Serve) system with negative renewal arrivals and killing strategy:RCH (Removal of Customer at the Head) and RCE(Removal of Customer at the End)are derived at the first time respectively.It is interesting that the results are evidently coincided with the known results in Harrison & pital (1996) when negative arrivals are poisson streams instead of the general renewal arrivals.

  15. Defect chemistry, thermomechanical and transport properties of (RE2 - xSrx)0.98(Fe0.8Co0.2)1 - yMgyO4 - δ (RE = La, Pr)

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Schönbeck, C.; Hagen, Anke

    2013-01-01

    gas mixture ([H 2]/[H2O] = 50). The thermal and chemical expansion coefficients of these compounds are significantly decreased compared to those of (La0.6Sr0.4)0.99Fe0.8Co 0.2O3 - δ, a well studied perovskite with related composition. The transport properties were investigated by conductivity......The oxygen nonstoichiometry of Ruddlesden-Popper compounds with chemical composition (RE2 - xSrx)0.98(Fe 0.8Co0.2)1 - yMgyO 4 - δ (RE = La, Pr, x = 0.9-1.2 and y = 0, 0.2) was measured as a function of temperature and oxygen activity (aO2) by coulometric titration and thermogravimetry. All...... compositions were found to be approximately stoichiometric in air (δ ≈ 0). The oxidation state of Fe and Co was determined by XANES. Fe retains an oxidation state of + 3 upon reduction of the sample, whereas Co is reduced to an oxidation state of + 2. A model of the defect chemistry is proposed that can...

  16. STOCHASTIC DECOMPOSITIONS FOR M/GI/1 TYPE SYSTEM WITH TWOKINDS OF SERVICE TIMES AND GENERAL VACATION POLICY%带两类服务的一般休假M/GI/1 型系统的随机分解

    Institute of Scientific and Technical Information of China (English)

    朱翼隽

    2001-01-01

    By use of the `Rate Conservation Law'(RCL), based on stationary pointprocess and Palm distribution theory, this paper discussed a M/GI/1 typeQueuing System with general vacation policy. The referred Model Permitscustomers coming in `idle period' with non-poisson intervals, andservices may be interrupted by server vacations. We get the stochasticdecomposition formulas in steady state for the workload of the systemand the queue length, seen by the customer before departure.%借助于建立在平稳点过程和Palm分布理论基础上的强度保守原理, 讨论了一个具有一般休假策略的 M/GI/1 型排队系统. 该模型允许闲期中顾客非泊松到达且顾客的服务可以被休假中断。我们得到了稳态下工作量和顾客离去前所见队长的随机分解.

  17. Directional Lya Equivalent Boosting I: Spherically Symmetric Distributions of Clumps

    CERN Document Server

    Gronke, Max

    2014-01-01

    We quantify the directional dependence of the escape fraction of Lyman-$\\alpha$ (Ly$\\alpha$) and non-ionising UV-continuum photons from a multiphase medium, and investigate whether there exist directional enhancements in the Ly$\\alpha$ equivalent width (EW). Our multiphase medium consists of spherically symmetric distributions of cold, dusty clumps embedded within a hot dust-free medium. We focus on three models from the analysis presented by Laursen et al. (2013). We find that for a Ly$\\alpha$ and UV-continuum point source, it is possible to find an EW boost $b(\\theta,\\phi) > 5 \\bar{b}$ in a few per cent of sight lines, where $\\bar{b}$ denotes the boost averaged over all photons. For spatially extended sources this directional dependence vanishes quickly when the size of the UV emitting region exceeds the mean distance between cold dusty clumps. Our analysis suggests that directional EW boosting can occur, and that this is mostly driven by reduced escape fractions of UV photons (which gives rise to UV-contin...

  18. Discovery of a Giant Lya Emitter Near the Reionization Epoch

    Energy Technology Data Exchange (ETDEWEB)

    Ouchi, Masami; Ono, Yoshiaki; Egami, Eiichi; Saito, Tomoki; Oguri, Masamune; McCarthy, Patrick J.; Farrah, Duncan; Kashikawa, Nobunari; Momcheva, Ivelina; Shimasaku, Kazuhiro; Nakanishi, Kouichiro; Furusawa, Hisanori; Akiyama, Masayuki; Dunlop, James S.; Mortier, Angela M.J.; Okamura, Sadanori; Hayashi, Masao; Cirasuolo, Michele; Dressler, Alan; Iye, Masanori; Jarvis, Matt.J.

    2008-08-01

    We report the discovery of a giant Ly{alpha} emitter (LAE) with a Spitzer/IRAC counterpart near the reionization epoch at z = 6.595. The giant LAE is found from the extensive 1 deg{sup 2} Subaru narrow-band survey for z = 6.6 LAEs in the Subaru/XMM-Newton Deep Survey (SXDS) field, and subsequently identified by deep spectroscopy of Keck/DEIMOS and Magellan/IMACS. Among our 207 LAE candidates, this LAE is not only the brightest narrow-band object with L(Ly{alpha}) = 3.9 {+-} 0.2 x 10{sup 43} erg s{sup -1} in our survey volume of 10{sup 6} Mpc{sup 3}, but also a spatially extended Ly{alpha} nebula with the largest isophotal area whose major axis is at least {approx_equal} 3-inches. This object is more likely to be a large Ly{alpha} nebula with a size of {approx}> 17-kpc than to be a strongly-lensed galaxy by a foreground object. Our Keck spectrum with medium-high spectral and spatial resolutions suggests that the velocity width is v{sub FWHM} = 251 {+-} 21 km s{sup -1}, and that the line-center velocity changes by {approx_equal} 60 km s{sup -1} in a 10-kpc range. The stellar mass and star-formation rate are estimated to be 0.9-5.0 x 10{sup 10}M{sub {circle_dot}} and > 34 M{sub {circle_dot}}yr{sup -1}, respectively, from the combination of deep optical to infrared images of Subaru, UKIDSS-Ultra Deep Survey, and Spitzer/IRAC. Although the nature of this object is not yet clearly understood, this could be an important object for studying cooling clouds accreting onto a massive halo, or forming-massive galaxies with significant outflows contributing to cosmic reionization and metal enrichment of inter-galactic medium.

  19. lya theory of hypercubes (revision of preprint 925)

    NARCIS (Netherlands)

    Lemmens, P.W.H.

    1996-01-01

    The cycle index polynomial is described for the action of the full isometry group of the n-dimensional hypercube on its q-dimensional cells. This group action is interpreted as C n 2 Sn acting on the set of unit basis vectors in R n and their opposites. A kind of generating function that yields all

  20. High redshift Lya emitters: clues on the Milky Way infancy

    CERN Document Server

    Salvadori, S; Ferrara, A

    2010-01-01

    With the aim of determining if Milky Way (MW) progenitors could be identified as high redshift Lyman Alpha Emitters (LAEs) we have derived the intrinsic properties of z ~ 5.7 MW progenitors, which are then used to compute their observed Lyman-alpha luminosity, L_alpha, and equivalent width, EW. MW progenitors visible as LAEs are selected according to the canonical observational criterion, L_alpha > 10^42 erg/s and EW > 20 A. Progenitors of MW-like galaxies have L_alpha = 10^(39-43.25) erg/s, making some of them visible as LAEs. In any single MW merger tree realization, typically only 1 (out of ~ 50) progenitor meets the LAE selection criterion, but the probability to have at least one LAE is very high, P = 68%. The identified LAE stars have ages, t_* ~ 150-400 Myr at z ~ 5.7 with the exception of five small progenitors with t_* 10% of the halo very metal-poor stars [Fe/H] < -2, thus establishing a potentially fruitful link between high-z galaxies and the Local Universe.

  1. Structural characterization and colour of MgxCu3-xV2O8 (0 ≤ x ≤ 3) and MgyCu2-yV2O7 (0 ≤ y ≤ 2) compositions.

    Science.gov (United States)

    Tena, M A; García-Granda, Santiago

    2015-01-01

    In this study, MgxCu3-xV2O8 (0 ≤ x ≤ 3) and MgyCu2-yV2O7 (0 ≤ y ≤ 2) compositions were synthesized by the chemical coprecipitation method and characterized by X-ray diffraction, UV-vis-NIR spectroscopy and CIE L* a* b* parameters measurements. Melting points of compounds Cu3V2O8 and Cu2V2O7 are 780°C and 790°C, respectively. The addition of small amounts of Mg (II), MgxCu3-xV2O8 (x < 1.0) and MgyCu2-yV2O7 (y < 0.5) fused compositions, was not sufficient to stabilize structures at 800°C. For the Mg2CuV2O8 (x = 2.0) composition fired at 800°C, Mg (II) incorporated into the monoclinic Cu3V2O8 structure stabilizes this crystalline phase. At 1000°C, orthorhombic Mg3V2O8 structure from this composition was obtained. Solid solutions with orthorhombic symmetry were detected from the prepared compositions fired at 1000°C when 1.0 ≤ x ≤ 3.0. The difference of coloration of Cu, Mg vanadates might be explained by the presence of a strong charge transfer band in visible spectra.

  2. A Decrease in NiO-MgO Phase Through Its Solid Solution Equilibrium with Tetragonal (La1−zSrz2Ni1−yMgyO4−δ: Effect on Catalytic Partial Oxidation of Methane

    Directory of Open Access Journals (Sweden)

    Xiong Yin

    2012-01-01

    Full Text Available Calcination of an oxide mixture consisting of 0.4 La2O3, 0.2 SrCO3, (1−xNiO, and xMgO at 800∘C results in an equilibrium between tetragonal (La1−zSrz2Ni1−yMgyO4−δ phase and NiO-MgO phase. Forming rock-salt NiO-MgO facilitates the NiO to join the tetragonal phase. The size of the NiO-MgO phase in the resulting composite is reduced with the increase in MgO (the x value. The composite thus obtained is used to catalyze partial oxidation of methane, and the maximum methane conversion of ca. 93% is achieved when x=0.2. A further rise in x value results in a monotonic decrease in the methane conversion. X-ray diffraction, electron microscopy, and chemosorption all confirm a decrease in both size and amount of the supported Ni0 clusters with the increase in MgO dosage. The reduction in size promotes the dispersion of Ni0 sites and gives rise to both high activity and strong coking resistance.

  3. Advanced Manufacturing Technologies (AMT): Materials Genome Initiative (MGI) Element

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop integrated computational/experimental/processing methodologies for accerlating discovery and insertion of mateirals to satisfy NASA's unique mission...

  4. Aktsendikorpus ja võõrkeele aktsendi uurimine / Lya Meister, Einar Meister

    Index Scriptorium Estoniae

    Meister, Lya

    2012-01-01

    Antakse ülevaade aktsendi olemusest ja teoreetilistest käsitlustest, tutvustatakse eesti keelt võõrkeelena kõnelevate inimeste hääldusnäidetel põhinevat, Tallinna Tehnikaülikooli juures loodavat aktsendikorpust, ka selle eesmärke, ülesehitust ja salvestusi

  5. Properties of Lya Emitters Around the Radio Galaxy MRC 0316-257

    Energy Technology Data Exchange (ETDEWEB)

    Venemans, B; Rottgering, H; Miley, G; Kurk, J; De Breuck, C; van Breugel, W; Carilli, C; Ford, H; Heckman, T; Pentericci, L; McCarthy, P

    2004-08-12

    Observations of the radio galaxy MRC 0316-257 at z = 3.13 and the surrounding field are presented. Using narrow- and broad-band imaging obtained with the VLT*, 92 candidate Ly{alpha} emitters with a rest-frame equivalent width of > 15 AngstromS were selected in a {approx} 7{prime} x 7{prime} field around the radio galaxy. Spectroscopy of 40 candidate emitters resulted in the discovery of 33 emission line galaxies of which 31 are Ly{alpha} emitters with redshifts similar to that of the radio galaxy, while the remaining two galaxies turned out to be [{omicron} II] emitters. The Ly{alpha} profiles had widths (FWHM) corresponding to 120-800 kms{sup -1},with a median of 260 kms{sup -1}. Where the signal-to-noise spectra was large enough, the Ly{alpha} profiles are found to be asymmetric, with apparent absorption troughs blueward of the profile peaks, indicative of absorption along the line of sight of an {Eta}{Iota} mass of 1-5000 {mu}{circle_dot}. Besides that of the radio galaxy and one of the emitters that is an QSO, the continuum of the emitters is faint, with luminosities ranging from 1.3 L{sub *} to < 0.03 L{sub *}.The colors of the confirmed emitters are, on average, very blue. The median UV continuum slope is {beta}=-1.65, bluer than the average slope of LBGs with Ly{alpha} emitters is 2.6 {Mu}{circle_dot}{sup -1} as measured by the Ly{alpha} emission line or < 3.9 {Mu}{circle_dot}{sup -1} as measured by the UV continuum. The properties of the Ly{alpha} galaxies (faint, blue and small) are consistent with young star forming galaxies which are nearly dust free. The density of Ly{alpha} emitting galaxies in the field around MRC 0316-257 is a factor of 3.3{sup +0.5}{sub -0.4} larger compared with the density of Ly{alpha} emitters at that redshift. The velocity distribution of the spectroscopically confirmed emitters has a dispersion of 640 km s{sup -1}, corresponding to a FWHM of 1510 km s{sup -1}, which is substantially smaller than the width of the narrow-band filter (FWHM {approx}3500km s{sup -1}). The peak of the velocity distribution is located with 200 kms{sup -1} of the redshift of the radio galaxy. We conclude the confirmed Ly{alpha} emitters are members of a protocluster of galaxies at z {approx}3.13. The size of the protocluster is unconstraint and is larger than 3.3x3.3 Mpc{sup 2}. The mass of this structure is estimated to be > 3-6 x 10{sup 14}{Mu}{circle_dot} and could be the precursor of a cluster of galaxies similar to e.g. the Virgo cluster.

  6. Mapping the Polarization of the Radio-Loud lya Nebula B3 J2330+3927

    Science.gov (United States)

    You, Chang; Zabludoff, Ann; Smith, Paul; Yang, Yujin; Kim, Eunchong; Jannuzi, Buell; Prescott, Moire K. M.; Matsuda, Yuichi; Lee, Myung Gyoon

    2017-01-01

    Lyα nebulae, or “Lyα blobs,” are extended (up to ∼100 kpc), bright (LLyα ≳ 1043 erg s‑1) clouds of Lyα emitting gas that tend to lie in overdense regions at z ∼ 2–5. The origin of the Lyα emission remains unknown, but recent theoretical work suggests that measuring the polarization might discriminate among powering mechanisms. Here we present the first narrowband imaging polarimetry of a radio-loud Lyα nebula, B3 J2330+3927, at z = 3.09, with an embedded active galactic nucleus (AGN). The AGN lies near the blob’s Lyα emission peak, and its radio lobes align roughly with the blob’s major axis. With the SPOL polarimeter on the 6.5 m MMT telescope, we map the total (Lyα + continuum) polarization in a grid of circular apertures of a radius of 0.″6 (4.4 kpc), detecting a significant (>2σ) polarization fraction P% in nine apertures and achieving strong upper limits (as low as 2%) elsewhere. P% increases from <2% at ∼5 kpc from the blob center to 17% at ∼15–25 kpc. The detections are distributed asymmetrically, roughly along the nebula’s major axis. The polarization angles θ are mostly perpendicular to this axis. Comparing the Lyα flux to that of the continuum and conservatively assuming that the continuum is highly polarized (20%–100%) and aligned with the total polarization, we place lower limits on the polarization of the Lyα emission P%,Lyα ranging from no significant polarization at ∼5 kpc from the blob center to 3%–17% at 10–25 kpc. Like the total polarization, the Lyα polarization detections occur more often along the blob’s major axis. The observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution.

  7. Mapping the low surface brightness Universe in the UV band with Lya emission from IGM filaments

    CERN Document Server

    Silva, Marta B; Zaroubi, Saleem

    2016-01-01

    A large fraction of the baryonic matter in the Universe is located in filaments in the intergalactic medium. However, the low surface brightness of these filaments has not yet allowed their direct detection except in very special regions in the circum-galactic medium (CGM). Here we simulate the intensity and spatial fluctuations in Lyman Alpha ${\\rm (Ly\\alpha)}$ emission from filaments in the intergalactic medium (IGM) and discuss the prospects for the next generation of space based instruments to detect the low surface brightness universe at UV wavelengths. Starting with a high resolution N-body simulation we obtain the dark matter density fluctuations and associate baryons with the dark matter particles assuming that they follow the same spatial distribution. The IGM thermal and ionization state is set by a model of the UV background and by the relevant cooling processes for a hydrogen and helium gas. The ${\\rm Ly\\alpha}$ emissivity is then estimated, taking into account recombination and collisional excita...

  8. BRIGHT Lights, BIG City: Massive Galaxies, Giant Ly-A Nebulae, and Proto-Clusters

    Energy Technology Data Exchange (ETDEWEB)

    van Breugel, W; Reuland, M; de Vries, W; Stanford, A; Dey, A; Kurk, J; Venemans, B; Rottgering, H; Miley, G; De Breuck, C; Dopita, M; Sutherland, R; Bland-Hawthorn, J

    2002-08-01

    High redshift radio galaxies are great cosmological tools for pinpointing the most massive objects in the early Universe: massive forming galaxies, active super-massive black holes and proto-clusters. They report on deep narrow-band imaging and spectroscopic observations of several z > 2 radio galaxy fields to investigate the nature of giant Ly-{alpha} nebulae centered on the galaxies and to search for over-dense regions around them. They discuss the possible implications for our understanding of the formation and evolution of massive galaxies and galaxy clusters.

  9. Lya escape from z~0.03 star-forming galaxies: the dominant role of outflows

    CERN Document Server

    Wofford, A; Salzer, J

    2013-01-01

    The usefulness of H I Lyman-alpha photons for characterizing star formation in the distant universe is limited by our understanding of the astrophysical processes that regulate their escape from galaxies. These processes can only be observed in detail out to a few x100 Mpc. Past nearby (z=0.03. The galaxies cover a broad range of luminosity, oxygen abundance, and reddening. In this paper, we characterize the observed Lyman-alpha lines and establish correlations with fundamental galaxy properties. We find seven emitters. These host young (\\le 10 Myr) stellar populations, have rest-frame equivalent widths in the range 1-12 \\AA, and have Lyman-alpha escape fractions within the COS aperture in the range 1-12 %. One emitter has a double-peaked Lyman-alpha with peaks 370 km/s apart and a stronger blue peak. Excluding this object, the emitters have Lyman-alpha and O I \\lambda 1302 offsets from H-alpha in agreement with expanding shell models and LBG observations. The absorbers have offsets that are almost consistent...

  10. Observations of radio galaxy mrc 1138-262: merging galaxies embedded in a giant Lya halo

    Directory of Open Access Journals (Sweden)

    J. D. Kurk

    2002-01-01

    Full Text Available La radio galaxia MRC 1138-262 a z = 2:16 probablemente es una galaxia de mayor brillo en el c umulo que se encuentra un estado inicial de evoluci on. Aqu presentamos observaciones del luminoso halo de l neas de emisi on y de las componentes estelares de esta radio galaxia. Las im agenes opticas de banda angosta en H muestran un halo mucho m as peque~no con una morfolog a muy diferente al halo Ly . Proponemos un modelo en el que la parte interior del halo est a fotoionizada directamente por iluminaci on del n ucleo activo de la galaxia o por fotones UV de estrellas j ovenes. Lejos del n ucleo ( 25 kpc hay una regi on de emisi on Ly muy aumentada. En esa posici on es probable que la ionizaci on por choques sea importante seg un indica la curvatura del radio jet. La espectroscop a de varias nubes de cont nuo en el halo muestra que, aunque hay diferencias entre las caracter sticas de emisi on y de absorci on de espectros de varias regiones, estas tienen propiedades similares a las galaxias con \\Lyman-break". Esto es evidencia adicional en favor de un escenario en que galaxias masivas se forman jer arquicamente a partir de bloques m as peque~nos.

  11. Aktsendikorpus ja võõrkeele aktsendi uurimine / Lya Meister, Einar Meister

    Index Scriptorium Estoniae

    Meister, Lya

    2012-01-01

    Antakse ülevaade aktsendi olemusest ja teoreetilistest käsitlustest, tutvustatakse eesti keelt võõrkeelena kõnelevate inimeste hääldusnäidetel põhinevat, Tallinna Tehnikaülikooli juures loodavat aktsendikorpust, ka selle eesmärke, ülesehitust ja salvestusi

  12. Structural, optical, and electrical properties of MgyTi1-yHx thin films

    NARCIS (Netherlands)

    Borsa, D. M.; Gremaud, R.; Baldi, A.; Schreuders, H.; Rector, J. H.; Kooi, B.; Notten, P. H. L.; Dam, B.; Griessen, R.

    The structural, optical, and electrical transformations induced by hydrogen absorption and/or desorption in Mg-Ti thin films prepared by co-sputtering of Mg and Ti are investigated. Highly reflective in the metallic state, the films become highly absorbing upon H absorption. The

  13. M/GI/1 MODELS WITH NEGATIVE ARRIVALS TO BE SERVED

    Institute of Scientific and Technical Information of China (English)

    ZHU Yijun

    2003-01-01

    On the basic of a type of practical examples we set upa new queueing model with negative customers. By the use of "Supplemental Variables method" and "State transfer analysis", we get the generating function with negative powers of queue length and the waiting time expressions.

  14. Structural, optical, and electrical properties of MgyTi1-yHx thin films

    NARCIS (Netherlands)

    Borsa, D. M.; Gremaud, R.; Baldi, A.; Schreuders, H.; Rector, J. H.; Kooi, B.; Notten, P. H. L.; Dam, B.; Griessen, R.

    2007-01-01

    The structural, optical, and electrical transformations induced by hydrogen absorption and/or desorption in Mg-Ti thin films prepared by co-sputtering of Mg and Ti are investigated. Highly reflective in the metallic state, the films become highly absorbing upon H absorption. The reflector-to-absorbe

  15. RENDS AND ISSUES IN DISTANCE EDUCATION: International Perspectives, Second Edition Edited by Lya Visser, Yusra Visser, Ray Amirault & Michael Simonson

    Directory of Open Access Journals (Sweden)

    Reviewed by Dilek ALTUNAY

    2013-07-01

    Full Text Available Over the last decade, the field of distance education (and e-learning has substantially strengthened and assumed a more international scope. There has been an impressive growth in the conceptual, empirical and experiential foundations of the field. Trends and Issues in Distance Education: International Perspectives (2nd Ed captures a representative snapshot of the breadth of current global trends and issues in distance education theory, research, and practice. Through 21 chapters (from over 30 international authors, the book documents new developments in distance education scholarship and practice, presenting a diverse set of viewpoints on the trends and issues affecting this increasingly central discipline. The book is for researchers, practitioners, and students. Chapters speak to the many creative ways in which distance education addresses learning and human development needs around the world. They focus on distance education in dissimilar settings that extend beyond the limitations of the dominating paradigms of the highly developed economies. Contributing authors touch upon conceptual as well as practical issues. They critically reflect on both large- and small-scale distance education initiatives, discussing the use of everything from the most advanced technologies (e.g., 3-D computing to the most rudimentary technologies (e.g., wind-up radios (Quated Amazon Pages This book makes a contribution to the field of distance education by offering a comprehensive overview and analysis of the current trends and issues in distance education. In addition, the book is well-organized and coherent in terms of presentation. The reader is guided by section editors who provides introduction to the sectio

  16. Conditions Within The Nucleus Nadi, Nagi,mdi ,mgiAnd Nuclear Energy Density And The Electric Field Parameters

    Directory of Open Access Journals (Sweden)

    Huang Zhenqiang and Huang Yuxiang

    2013-10-01

    Full Text Available By (7.2, charged elementary particles in the fluctuation, the spin track movement in the direction of comprehensive force analysis and calculation results show that charged particle in electric and magnetic field force, nuclear power field force, under the action of centrifugal force is along the wave vector rail inside diameter automatic shrinkage in the center of the trend. From figure 7.1 and figure 7.1 within the nucleus of the high and low particles spiral loop combination structure can also be seen in: each layer low-energy particles spiral ring of the spin track occupied space should be minimal, get recently, and not overlap. 2 ~ 5 layers of each pair of high and low particles spiral ring on the inside of the spin track Rθgi(0, Rθdi(0 in also is such. All high, low-energy particle spiral ring in addition to the first layer, the quantum fluctuations of Nadi, Nagi shall take natural number.Refer to section 7.1 of the nucleus kernel forces forming principle, by figure 9.1 low-energy particles spiralring layer combination that: the bottom low-energy particles spiral ring in excess πd-both in the spin track intersec ting in the formation of ampere force can cover the economical and the upper surplus high and low π± muon solenoid ring particles of the axial electric field force, should be comprehensive comparison a, b, c, d,... each boundary point, internal non-oil imports all the ampere force and comprehensive relationship between the size of the axial electric field force and. That as space limit set of geometric conditions, by figure 9.1, the first a1 a1 > 150°. According to the set position and fluctuation, the relationship between the spin track parameters, low-energy particles spiral ring of n side by side, we

  17. On the Doppler Shift and Asymmetry of Stokes Profiles of Photospheric FeI and Chromospheric MgI Lines

    Science.gov (United States)

    2010-06-15

    Solanki 1995). Theoretical calculation (Altrock & Canfield 1974; Lites et al. 1988; Mauas et al. 1988) and observational analysis (Briand & Solanki 1998...Degenhardt, D. 1994, ApJ, 425, L113 Mauas , P. J., Avrett, E. H., & Loeser, R. 1988, ApJ, 330, 1008 Mickey, D. L. 1985, Sol. Phys., 97, 223 Rimmele

  18. MUSE Deep-Fields: The Lya Luminosity Function in the Hubble Deep Field South at 2.91 < z < 6.64

    CERN Document Server

    Drake, Alyssa B; Blaizot, Jeremy; Wisotzki, Lutz; Herenz, Edmund Christian; Garel, Thibault; Richard, Johan; Bacon, Roland; Bina, David; Cantalupo, Sebastiano; Contini, Thierry; Brock, Mark den; Hashimoto, Takuya; Marino, Raffaella Anna; Pello, Roser; Schaye, Joop; Schmidt, Kasper B

    2016-01-01

    We present the first estimate of the Ly{\\alpha} luminosity function using blind spectroscopy from the Multi Unit Spectroscopic Explorer, MUSE, in the Hubble Deep Field South. Using automatic source-detection software, we assemble a homogeneously-detected sample of 59 Ly{\\alpha} emitters covering a flux range of -18.0 < log10 (F) < -16.3 (erg s^-1 cm^-2), corresponding to luminosities of 41.4 < log10 (L) < 42.8 (erg s^-1). As recent studies have shown, Ly{\\alpha} fluxes can be underestimated by a factor of two or more via traditional methods, and so we undertake a careful assessment of each object's Ly{\\alpha} flux using a curve-of-growth analysis to account for extended emission. We describe our self-consistent method for determining the completeness of the sample, and present an estimate of the global Ly{\\alpha} luminosity function between redshifts 2.91 < z < 6.64 using the 1/Vmax estimator. We find the luminosity function is higher than many number densities reported in the literature by ...

  19. lya Kasapoğlu Çengel, Kırgız Türkçesi Grameri Ses ve Şekil Bilgisi

    OpenAIRE

    ÖZDARENDELİ, Nursel

    2014-01-01

    kında bilgi verilmiş, daha sonra Kırgız Türkçesindeki ses özellikleri ve olayları ayrıntılı olarak ele alınmıştır. Bu bölüm, eserde 44 sayfalık bir yer tutmaktadır. Ses özellikleri ve olayları değerlendirilirken yazar, alıntı kelimelerdeki ses olaylarını orijinal dillere göre tek tek değerlendirmiştir. Alıntı kelimelerin de, diğer unsurlarla birlikte değerlendirme- ye alındığı dilbilgisi kitaplarında, bu durum, Genel Türkçeye ait kimi ses özelliklerinin belirlenmesinde karışıklık yaratma...

  20. Shadow of a Colossus: A z=2.45 Galaxy Protocluster Detected in 3D Ly-a Forest Tomographic Mapping of the COSMOS Field

    CERN Document Server

    Lee, Khee-Gan; White, Martin; Prochaska, J Xavier; Font-Ribera, Andreu; Schlegel, David J; Rich, R Michael; Suzuki, Nao; Stark, Casey W; Fevre, Olivier Le; Nugent, Peter E; Salvato, Mara; Zamorani, Gianni

    2015-01-01

    Using moderate-resolution optical spectra from 58 background Lyman-break galaxies and quasars at $z\\sim 2.3-3$ within a $11.5'\\times13.5'$ area of the COSMOS field ($\\sim 1200\\,\\mathrm{deg}^2$ projected area density or $\\sim 2.4\\,h^{-1}\\,\\mathrm{Mpc}$ mean transverse separation), we reconstruct a 3D tomographic map of the foreground Ly$\\alpha$ forest absorption at $2.2

  1. Süüteovahendi konfiskeerimise eesmärk ja õiguslik olemus ning selle põhiseaduslik õigustus. Riigikohtu üldkogu otsus asjas 3-1-1-37-07 / Andres Parmas

    Index Scriptorium Estoniae

    Parmas, Andres, 1977-

    2008-01-01

    Riigikohtu lahendist 3-1-1-37-07 (Toomas Tiiki kaitsja vandeadvokaadi abi Anti Aasmaa kassatsioon Viru Ringkonnakohtu 22. märtsi 2007. a kohtuotsuse peale kriminaalasjas Toomas Tiiki süüdistuses KarS § 424 järgi)

  2. Süüteovahendi konfiskeerimise eesmärk ja õiguslik olemus ning selle põhiseaduslik õigustus. Riigikohtu üldkogu otsus asjas 3-1-1-37-07 / Andres Parmas

    Index Scriptorium Estoniae

    Parmas, Andres, 1977-

    2008-01-01

    Riigikohtu lahendist 3-1-1-37-07 (Toomas Tiiki kaitsja vandeadvokaadi abi Anti Aasmaa kassatsioon Viru Ringkonnakohtu 22. märtsi 2007. a kohtuotsuse peale kriminaalasjas Toomas Tiiki süüdistuses KarS § 424 järgi)

  3. Use of the Materials Genome Initiative (MGI approach in the design of improved-performance fiber-reinforced SiC/SiC ceramic-matrix composites (CMCs

    Directory of Open Access Journals (Sweden)

    Jennifer S. Snipes

    2016-07-01

    Full Text Available New materials are traditionally developed using costly and time-consuming trial-and-error experimental efforts. This is followed by an even lengthier material-certification process. Consequently, it takes 10 to 20 years before a newly-discovered material is commercially employed. An alternative approach to the development of new materials is the so-called materials-by-design approach within which a material is treated as a complex hierarchical system, and its design and optimization is carried out by employing computer-aided engineering analyses, predictive tools and available material databases. In the present work, the materials-by-design approach is utilized to design a grade of fiber-reinforced (FR SiC/SiC ceramic matrix composites (CMCs, the type of materials which are currently being used in stationary components, and are considered for use in rotating components, of the hot sections of gas-turbine engines. Towards that end, a number of mathematical functions and numerical models are developed which relate CMC constituents’ (fibers, fiber coating and matrix microstructure and their properties to the properties and performance of the CMC as a whole. To validate the newly-developed materials-by-design approach, comparisons are made between experimentally measured and computationally predicted selected CMC mechanical properties. Then an optimization procedure is employed to determine the chemical makeup and processing routes for the CMC constituents so that the selected mechanical properties of the CMCs are increased to a preset target level.

  4. Synthesis and characterization of BaxMgyAl2O4: Eu,Dy nanophosphors prepared using solution-combustion method

    CSIR Research Space (South Africa)

    Kebede, MA

    2011-07-01

    Full Text Available angles due to differences in size between Ba and Mg ions. The peak of the emission band occurs at longer wavelength (around 615nm) with increase in Mg concentration but display a broad band emission at 498 nm for lower Mg concentration. The blue-green...

  5. The feasibility and acceptability of using the Mother-Generated Index (MGI) as a Patient Reported Outcome Measure in a randomised controlled trial of maternity care

    National Research Council Canada - National Science Library

    Symon, Andrew; Downe, Soo; Finlayson, Kenneth William; Knapp, Rebecca; Diggle, Peter

    2015-01-01

    Using patient-reported outcome measures (PROMs) to assess Quality of Life (QoL) is well established, but commonly-used PROM item-sets do not necessarily capture what all respondents consider important...

  6. Preparation, structure and ionic conductivity of ABO3-type solid electrolyte La1-xSrxGa1-yMgyO3-α%ABO3型固体电解质La1-xSrxGa1-yMgyO3-α制备与导电性

    Institute of Scientific and Technical Information of China (English)

    赵捷; 王志奇; 包俊成; 李建平; 孙家枢

    2006-01-01

    用固相反应法合成La0.8Sr0.2Ga0.85Mg0.15O2.825(LSGM2015)和La0.8Sr0.2Ga0 75Mg0.25O2.775(LSGM2025)固体电解质,利用XRD、EDS、直流四电极法、SEM等现代测试手段对LSGM2015和LSGM2025的成分、晶体结构、、离子导电性及显微组织等进行研究.实验结果表明:合成的LSGM2015和LSGM2025均属正交晶系,具有钙钛矿结构,样品纯度较高,基本上无杂相;其电导率与温度的关系服从Arrhenius方程,均表现出离子导电特征.LSGM2015和LSGM2025的离子迁移活化能(Ea)相近且较低(<l eV),在试验温度范围内LS-GM2015的离子导电性明显高于LSGM2025,低价金属Sr、Mg的适量掺杂有利于电导率的提高.

  7. Study on structure and electrical property of compositely doped oxide La1-xsrxGa1-yMgyO3-α%复合掺杂氧化物La1-xSrxGa1-yMgyO3-δ的结构与电性能研究

    Institute of Scientific and Technical Information of China (English)

    赵捷; 王志奇; 包俊成; 马叙; 李建平

    2006-01-01

    用固相反应法合成低价离子Sr、Mg复合掺杂的ABO3型氧化物La0.9Sr0.1Ga0.85Mg0.15O2.875(LSGM1015)La0.9Sr0.1Ga0.75Mg0.25O2.825(LSGM1025);借助EDS、XRD、SEM、直流四电极法等对LSGM1015和LSGM1025的微区成分、晶体结构、断面显微组织及导电性等进行研究.EDS和XRD分析表明:合成的LSGM1015和LSGM1025样品中杂质元素很少,且具有正交钙钛矿结构,基本上不含杂相;电导率测试结果表明:在673~1073 K温度区间,其电导率与温度的关系符合Arrhenius定律,说明LSGM1015和LSGM1025为氧离子导体,且离子迁移活化能Ea≈1 eV;Sr、Mg复合掺杂量较多(x+y=0.35)的LSGM1025具有较高的离子电导率.

  8. HATA TÜRÜ VE ETKİLERİ ANALİZİ (FMEA TEKNİĞİNİN MOBİLYA ENDÜSTRİSİNE YÖNELİK UYGULAMASI

    Directory of Open Access Journals (Sweden)

    Yüksel TAŞ

    2013-01-01

    Full Text Available FMEA (Hata Türü ve Etkileri Analizi tekniği, hataları ortaya çıkmadan önlemeye yönelik çok güçlü bir sayısal analiz tekniğidir. Bu çalışmada, FMEA çeşitlerinden biri olan proses FMEA çalışmasının mobilya endüstrisine yönelik örnek bir uygulaması yapılmıştır. Araştırma CNC makinelere sahip, kalite güvencesine yönelen bir işletmede gerçekleştirilmiş, uygulama sonucu karşılaşılan hata türleri ile ilgili nedenlerin yok edilmesine veya azaltılmasına, prosesi iyileştirecek değişikliklerin belirlenmesine ve uygulanmasına çalışılmıştır. Araştırma sonucunda, olası hata türleri ortaya çıkmış ve bu hata türleri tanımlanmıştır. Böylece benzer işletmeler ve çalışanlar için hata türleri ile karşılaşıldığında nasıl bir yol izleneceği ve hangi yöntemlerin uygulanacağının farkındalığı sağlanmıştır. İşletme için hata oluşumunu önleme yönelik rehber sayılabilecek nitelikteki örnek faaliyetler yapılmış ve kalitesizlik maliyetlerinin düşürülmesi sağlanmıştır. Özetle mobilya işletmesinde FMEA yöntemi uygulamasında uygulama öncesi ve sonrası değerler karşılaştırıldığında; hata türlerinde, sayı, şiddet ve olasılık olarak 1 ile 6 kat arasında azalma gerçekleşmiş, işletmede kalite güvencesinin sağlanmasına yönelik önemli bir gelişme sağlanmıştır.

  9. Requalifying the Built Environment: Challenges and Responses. By Roderick J. Lawrence, Hülya Turgut, Peter Kellett, Hogrefe, 2012; 232 pages. Price: 54,95€, ISBN 978-0-88937-430-0

    Directory of Open Access Journals (Sweden)

    Shu-Kun Lin

    2013-01-01

    Full Text Available In recent decades, significant financial and professional resources have been invested in urban regeneration, housing renovation, and the revitalization of old neighborhoods, with considerable impacts on the social, physical, and economic structure of cities and their inhabitants. The first objective of this volume is to present the key issues related to these changes, which were discussed at an international symposium of experts organized by the International Association for People-Environment Studies and Housing and CSBE (Culture and Space in the Built Environment Networks in Istanbul. The second objective is to show how concepts and methods in the field of people-environment studies can be successfully applied to study complex questions related to the revitalization of the built environment, both at the small scale of specific buildings and at the larger scale of neighborhoods.

  10. New Perspective on Galaxy Outflows From the First Detection of Both Intrinsic and Traverse Metal-Line Absorption

    CERN Document Server

    Kacprzak, Glenn G; Bouché, Nicolas; Churchill, Christopher W; Cooke, Jeff; LeReun, Audrey; Schroetter, Ilane; Ho, Stephanie H; Klimek, Elizabeth

    2014-01-01

    We present the first observation of a galaxy (z=0.2) that exhibits metal-line absorption back-illuminated by the galaxy ("down-the-barrel") and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by MgII, are blueshifted relative to the galaxy systemic velocity. The quasar sight-line, which resides almost directly along the projected minor axis of the galaxy, probes MgI and MgII absorption obtained from Keck/LRIS and Lya, SiII and SiIII absorption obtained from HST/COS. For the first time, we combine two independent models used to quantify the outflow properties for down-the-barrel and transverse absorption. We find that the modeled down-the-barrel deprojected outflow velocities range between $V_{dtb}=45-255$ km/s. The transverse bi-conical outflow model, assuming constant-velocity flows perpendicular to the disk, requires wind velocities $V_{outflow}=40-80$ km/s to reproduce the transverse MgII absorption kinematics, which is consistent with the range of $V_...

  11. Ultraviolet-Bright, High-Redshift ULIRGS

    CERN Document Server

    Colbert, J W; Francis, P; Palunas, P; Williger, G M; Woodgate, B; Colbert, James W.; Teplitz, Harry; Francis, Paul; Palunas, Povilas; Williger, Gerard M.; Woodgate, Bruce

    2006-01-01

    We present Spitzer Space Telescope observations of the z=2.38 lya-emitter over-density associated with galaxy cluster J2143-4423, the largest known structure (110 Mpc) above z=2. We imaged 22 of the 37 known lya-emitters within the filament-like structure, using the MIPS 24um band. We detected 6 of the lya-emitters, including 3 of the 4 clouds of extended (>50 kpc) lyman alpha emission, also known as Lya Blobs. Conversion from rest-wavelength 7um to total far-infrared luminosity using locally derived correlations suggests all the detected sources are in the class of ULIRGs, with some reaching Hyper-LIRG energies. Lya blobs frequently show evidence for interaction, either in HST imaging, or the proximity of multiple MIPS sources within the Lya cloud. This connection suggests that interaction or even mergers may be related to the production of Lya blobs. A connection to mergers does not in itself help explain the origin of the Lya blobs, as most of the suggested mechanisms for creating Lya blobs (starbursts, AG...

  12. Were progenitors of local L* galaxies Lyman-alpha emitters at high redshift?

    CERN Document Server

    Yajima, Hidenobu; Zhu, Qirong; Abel, Tom; Gronwall, Caryl; Ciardullo, Robin

    2011-01-01

    The Lya emission has been observed from galaxies over a redshift span z ~ 0 - 8.6. However, the link between high-redshift Lya emitters (LAEs) and local galaxies is largely unknown. Here, we investigate the Lya properties of progenitors of a local L^{*} galaxy by combining cosmological hydrodynamic simulations with three-dimensional radiative transfer calculations using the new ART^2 code. We find that the modeled galaxies are Lya bright in redshift z= 0 - 10. In particular, the Lya luminosities of some massive progenitors at z ~ 2 - 6 are close to the observed characteristic L_{Lya}^{*} of LAEs in that redshift range. Both Lya photon escape fraction and line equivalent width increase with redshift. The Lya escape fraction correlates with a number of physical properties of the galaxy, such as mass, SFR and metallicity. We find a "viewing-angle scatter" in which the photon escape depends strongly on the galaxy morphology and orientation. Moreover, we find that high-redshift LAEs show blue-shifted Lya line prof...

  13. The LyA-LyC Connection: Evidence for an Enhanced Contribution of UV-faint Galaxies to Cosmic Reionization

    CERN Document Server

    Dijkstra, Mark

    2016-01-01

    The escape of ionizing Lyman Continuum (LyC) photons requires the existence of low-N_HI sightlines, which also promote escape of Lyman-Alpha (Lya). We use a suite of 2500 Lya Monte-Carlo radiative transfer simulations through models of dusty, clumpy interstellar (`multiphase') media from Gronke & Dijkstra (2016), and compare the escape fractions of Lya [f_esc(Lya)] and LyC radiation [f_esc(LyC)]. We find that f_esc(LyC) and f_esc(Lya) are correlated: galaxies with a low f_esc(Lya) consistently have a low f_esc(LyC), while galaxies with a high f_esc(Lya) exhibit a large dispersion in f_esc(LyC). We argue that there is increasing observational evidence that Lya escapes more easily from UV-faint galaxies. The correlation between f_esc(LyC) and f_esc(Lya) then implies that UV-faint galaxies contribute more to the ionizing background than implied by the faint-end slope of the UV-luminosity function. In multiphase gases, the ionizing escape fraction is most strongly affected by the cloud covering factor, f_cl, ...

  14. The Luminosity Function of Lyman alpha Emitters at Redshift z=7.7

    CERN Document Server

    Tilvi, Vithal; Hibon, Pascale; Malhotra, Sangeeta; Wang, Junxian; Veilleux, Sylvain; Swaters, Rob; Probst, Ron; Krug, Hannah; Finkelstein, Steven L; Dickinson, Mark

    2010-01-01

    Lyman alpha (Lya) emission lines should be attenuated in a neutral intergalactic medium (IGM). Therefore the visibility of Lya emitters at high redshifts can serve as a valuable probe of reionization at about the 50% level. We present an imaging search for z=7.7 Lya emitting galaxies using an ultra-narrowband filter (filter width= 9A) on the NEWFIRM imager at the Kitt Peak National Observatory. We found four candidate Lya emitters in a survey volume of 1.4 x 10^4 Mpc^3, with a line flux brighter than 6x10^-18 erg/cm^2/s (5 sigma in 2" aperture). We also performed a detailed Monte-Carlo simulation incorporating the instrumental effects to estimate the expected number of Lya emitters in our survey, and found that we should expect to detect one Lya emitter, assuming a non-evolving Lya luminosity function (LF) between z=6.5 and z=7.7. Even if one of the present candidates is spectroscopically confirmed as a z~8 Lya emitter, it would indicate that there is no significant evolution of the Lya LF from z=3.1 to z~8. ...

  15. Mapping the Polarization of the Radio-Loud Ly$\\alpha$ Nebula B3 J2330+3927

    CERN Document Server

    You, Chang; Smith, Paul; Yang, Yujin; Kim, Eunchong; Jannuzi, Buell; Prescott, Moire K M; Matsuda, Yuichi; Lee, Myung Gyoon

    2016-01-01

    Lya nebulae, or "Lya blobs", are extended (up to ~100 kpc), bright (L[Lya] > 10^43 erg/s) clouds of Lya emitting gas that tend to lie in overdense regions at z ~ 2--5. The origin of the Lya emission remains unknown, but recent theoretical work suggests that measuring the polarization might discriminate among powering mechanisms. Here we present the first narrowband, imaging polarimetry of a radio-loud Lya nebula, B3 J2330+3927 at z=3.09, with an embedded active galactic nucleus (AGN). The AGN lies near the blob's Lya emission peak and its radio lobes align roughly with the blob's major axis. With the SPOL polarimeter on the 6.5m MMT telescope, we map the total (Lya + continuum) polarization in a grid of circular apertures of radius 0.6" (4.4kpc), detecting a significant (>2sigma) polarization fraction P in nine apertures and achieving strong upper-limits (as low as 2%) elsewhere. P increases from <2% at ~5kpc from the blob center to ~17% at ~15-25kpc. The detections are distributed asymmetrically, roughly ...

  16. The Coffee-Milk Mixture Problem Revisited

    Science.gov (United States)

    Marion, Charles F.

    2015-01-01

    This analysis of a problem that is frequently posed at professional development workshops, in print, and on the Web--the coffee-milk mixture riddle--illustrates the timeless advice of George Pólya's masterpiece on problem solving in mathematics, "How to Solve It." In his book, Pólya recommends that problems previously solved and put…

  17. Large-scale clustering of Lyman-alpha emission intensity from SDSS/BOSS

    CERN Document Server

    Croft, Rupert A C; Zheng, Zheng; Bolton, Adam; Dawson, Kyle S; Peterson, Jeffrey B; York, Donald G; Eisenstein, Daniel; Brinkmann, Jon; Brownstein, Joel; Delubac, Timothée; Font-Ribera, Andreu; Hamilton, Jean-Christophe; Lee, Khee-Gan; Myers, Adam; Palanque-Delabrouille, Nathalie; Pâris, Isabelle; Petitjean, Patrick; Pieri, Matthew M; Ross, Nicholas P; Rossi, Graziano; Schlegel, David J; Schneider, Donald P; Slosar, Anže; Vazquez, José; Viel, Matteo; Weinberg, David H; Yèche, Christophe

    2015-01-01

    (Abridged) We detect the large-scale structure of Lya emission in the Universe at redshifts z=2-3.5 by measuring the cross-correlation of Lya surface brightness with quasars in SDSS/BOSS. We use a million spectra targeting Luminous Red Galaxies at z, the amplitude of mass fluctuations, and the quasar and Lya emission bias factors. Using known values, we infer (b_alpha/3) = (3.9 +/- 0.9) x 10^-21 erg/s cm^-2 A^-1 arcsec^-2, where b_alpha is the Lya emission bias factor. If the dominant sources of Lya emission are star forming galaxies, we infer rho_SFR = (0.28 +/- 0.07) (3/b_alpha) /yr/Mpc^3 at z=2-3.5. For b_alpha=3, this value is a factor of 21-35 above previous estimates from individually detected Lya emitters, although consistent with the total rho_SFR derived from dust-corrected, continuum UV surveys. 97% of the Lya emission in the Universe at these redshifts is therefore undetected in previous surveys of Lya emitters. Our measurement is much greater than seen from stacking analyses of faint halos surroun...

  18. On an extension of Pólya’s Positivstellensatz

    NARCIS (Netherlands)

    Dickinson, Peter James Clair; Povh, Janez

    In this paper we provide a generalization of a Positivstellensatz by Pólya [Pólya in Naturforsch Ges Zürich 73:141–145 1928]. We show that if a homogeneous polynomial is positive over the intersection of the non-negative orthant and a given basic semialgebraic cone (excluding the origin), then there

  19. The Coffee-Milk Mixture Problem Revisited

    Science.gov (United States)

    Marion, Charles F.

    2015-01-01

    This analysis of a problem that is frequently posed at professional development workshops, in print, and on the Web--the coffee-milk mixture riddle--illustrates the timeless advice of George Pólya's masterpiece on problem solving in mathematics, "How to Solve It." In his book, Pólya recommends that problems previously solved and put…

  20. The BOSS Lyman-alpha Forest Sample from SDSS Data Release 9

    CERN Document Server

    Lee, Khee-Gan; Bartsch, Leslie E; Carithers, William; Dawson, Kyle S; Kirkby, David; Lundgren, Britt; Margala, Daniel; Palanque-Delabrouille, Nathalie; Pieri, Matthew M; Schlegel, David J; Weinberg, David H; Yeche, Christophe; Aubourg, Eric; Bautista, Julian; Bizyaev, Dmitry; Blomquist, Michael; Bolton, Adam S; Borde, Arnaud; Brewington, Howard; Busca, Nicolas G; Croft, Rupert A C; Delubac, Timothee; Ebelke, Garrett; Eisenstein, Daniel J; Font-Ribera, Andreu; Ge, Jian; Hamilton, Jean-Christophe; Hennawi, Joseph F; Ho, Shirley; Honscheid, Klaus; Goff, Jean-Marc Le; Malanushenko, Elena; Malanushenko, Viktor; Miralda-Escude, Jordi; Myers, Adam D; Noterdaeme, Pasquier; Oravetz, Daniel; Pan, Kaike; Paris, Isabelle; Petitjean, Patrick; Rich, James; Rollinde, Emmanuel; Ross, Nicholas P; Rossi, Graziano; Schneider, Donald P; Simmons, Audrey; Snedden, Stephanie; Slosar, Anze; Spergel, David N; Suzuki, Nao; Viel, Matteo; Weaver, Benjamin A

    2012-01-01

    We present the BOSS Lyman-alpha (Lya) Forest Sample from SDSS Data Release 9, comprising 54,468 quasar spectra with zqso > 2.15 suitable for Lya forest analysis. This data set probes the intergalactic medium with absorption redshifts 2.0 1216 Ang), extrapolated into the forest region and normalized by a linear function to fit the expected evolution of the Lya forest mean-flux. The estimated continuum errors are ~5% rms. We also discuss possible systematics arising from uncertain spectrophotometry and artifacts in the flux calibration; global corrections for the latter are provided. Our sample provides a convenient starting point for users to analyze clustering in BOSS Lya forest data, and it provides a fiducial data set that can be used to compare results from different analyses of baryon acoustic oscillations in the Lya forest. The full data set is available from the SDSS-III DR9 web site.

  1. Accelerated Evolution of Ly$\\alpha$ Luminosity Function at $\\textit{z} \\gtrsim 7$ Revealed by the Subaru Ultra-Deep Survey for Ly$\\alpha$ Emitters at $\\textit{z}=7.3$

    CERN Document Server

    Konno, Akira; Ono, Yoshiaki; Shimasaku, Kazuhiro; Shibuya, Takatoshi; Furusawa, Hisanori; Nakajima, Kimihiko; Naito, Yoshiaki; Momose, Rieko; Yuma, Suraphong; Iye, Masanori

    2014-01-01

    We present the ultra-deep Subaru narrowband imaging survey for Lya emitters (LAEs) at $z=7.3$ in SXDS and COSMOS fields with a total integration time of 106 hours. Exploiting our new sharp bandwidth filter, NB101, installed on Suprime-Cam, we have reached $L(Lya)=2.4\\times10^{42} \\ erg \\ s^{-1}$ ($5\\sigma$) for $z=7.3$ LAEs, about 4 times deeper than previous Subaru $z \\gtrsim 7$ studies, which allows us to reliably investigate evolution of Lya luminosity function (LF), for the first time, down to the luminosity limit same as those of Subaru $z=3.1-6.6$ LAE samples. Surprisingly, we only find three and four LAEs in SXDS and COSMOS fields, respectively, while one expects a total of $\\sim 65$ LAEs by our survey in the case of no Lya LF evolution from $z=6.6$ to $7.3$.We identify a decrease of Lya LF from $z=6.6$ to $7.3$ at the $>90\\%$ confidence level from our $z=7.3$ Lya LF.Moreover, the evolution of Lya LF is clearly accelerated at $z>6.6$ beyond the measurement uncertainties including cosmic variance. Becau...

  2. Keck Spectroscopy of Faint 3

    CERN Document Server

    Stark, Daniel P; Chiu, Kuenley; Ouchi, Masami; Bunker, Andrew

    2010-01-01

    We present results from a new Keck spectroscopic survey of UV-faint LBGs in the redshift range 3Lya emitters within the continuum-selected dropouts. By quantifying how the "Lya fraction" varies with redshift, we seek to constrain changes in Lya transmission associated with reionisation. In order to distinguish the effects of reionisation from other factors which affect the Lya fraction (e.g. dust, ISM kinematics), we study the luminosity and redshift-dependence of the Lya fraction over 3Lya emission much more frequently than luminous systems, and that at fixed luminosity, the prevalence of strong Lya emissio...

  3. Lyman Alpha Signatures from Direct Collapse Black Holes

    CERN Document Server

    Dijkstra, Mark; Sobral, David

    2016-01-01

    `Direct collapse black holes' (DCBHs) provide possible seeds for supermassive black holes that exist at redshifts as high as z~7. We study Lyman Alpha (Lya) radiative transfer through simplified representations of the DCBH-scenario. We find that gravitational heating of the collapsing cloud gives rise to a Lya cooling luminosity of up to ~ 1e38(M_gas/1e6 Msun)^2 erg/s. The Lya production rate can be significantly larger during the final stages of collapse, but collisional deexcitation efficiently suppresses the emerging Lya flux. Photoionization by a central source boosts the Lya luminosity to L~1e43(M_BH/1e6 M_sun) erg/s during specific evolutionary stages of the cloud, where M_BH denotes the mass of the black hole powering this source. We predict that the width and velocity off-set of the Lya spectral line range from a few tens to few thousands km/s, depending sensitively on the evolutionary state of the cloud. We also compare our predictions to observations of CR7 (Sobral et al. 2015), a luminous Lya emitt...

  4. A Cluster of Low-Redshift Lyman-$\\alpha$ Clouds toward PKS 2155-304; 1, Limits on Metals and D/H

    CERN Document Server

    Shull, J M; Stocke, J T; Giroux, M L; Van Gorkom, J H; Lee, Y H; Carilli, C L; Penton, Steven V.; Stocke, John T.; Giroux, Mark L.; Lee, Yong-Han; Carilli, Chris

    1998-01-01

    We report observations from the Hubble Space Telescope (HST) and the VLA on the galactic environment, metallicity, and D/H in strong low-redshift Lya absorption systems toward the bright BL Lac object PKS 2155-304. GHRS/G160M spectra at 20 km/s resolution show 14 Lya absorbers, 6 clustered at cz = 16,100-18,500 km/s. ORFEUS claimed LyC absorption at z = 0.056 with N(HI) = (2-5)x10^16 cm^-2, while our Lya data suggest N(HI) = (3-10)x10^14 cm^-2. Higher columns are possible if the Lya line core at 17,000 +/- 50 km/s contains narrow HI components. We identify the Lya cluster with a group of five HI galaxies offset by 400-800 kpc from the sightline. The two strongest absorption features cover the same velocity range as the HI emission in the two galaxies closest to the line of sight. If the Lya is associated with these galaxies, they must have huge halos of highly turbulent, mostly ionized gas. The Lya absorption could also arise from an extended sheet of intragroup gas, or from smaller primordial clouds and halo...

  5. The Lyman alpha Reference Sample VI: Lyman alpha escape from the edge-on disk galaxy Mrk1486

    CERN Document Server

    Duval, Florent; Hayes, Matthew; Zackrisson, Erik; Verhamme, Anne; Orlitova, Ivana; Adamo, Angela; Guaita, Lucia; Melinder, Jens; Cannon, John M; Laursen, Peter; Rivera-Thorsen, Thoger; Herenz, E Christian; Gruyters, Pieter; Mas-Hesse, J Miguel; Kunth, Daniel; Sandberg, Andreas; Schaerer, Daniel; Mansson, Tore

    2015-01-01

    While numerical simulations suggest that the strength of the Lyman alpha (Lya) line of star-forming disk galaxies strongly depends on the inclination at which they are observed (i.e. from edge-on to face-on, we expect to see a change from an attenuated Lya line to a strong Lya emission line), recent observations with the Hubble space telescope (HST) have highlighted few low-redshift highly inclined (edge-on) disk galaxies that breaks this trend. We aim to understand how a strong Lya emission line is able to escape from one of those inclined disk galaxies, named Mrk1486 (z=0.0338). For that purpose we used a large set of HST imaging and spectroscopic data to investigate both the ISM structure and the dominant source of Lya radiation inside Mrk1486. Moreover, we used a 3D Monte Carlo Lya radiation transfer code to study the radiative transfer of Lya and UV continuum photons inside a 3D geometry of neutral hydrogen (HI) and dust that models the ISM structure at the galaxy center. The analysis of IFU Halpha spect...

  6. Lyman-alpha spectral properties of five newly discovered Lyman continuum emitters

    CERN Document Server

    Verhamme, A; Schaerer, D; Izotov, Y; Worseck, G; Thuan, T X; Guseva, N

    2016-01-01

    We have recently reported the discovery of five low redshift Lyman continuum (LyC) emitters (LCEs, hereafter) with absolute escape fractions fesc(LyC) ranging from 6 to 13%, higher than previously found, and which more than doubles the number of low redshift LCEs.We use these observations to test theoretical predictions about a link between the characteristics of the Lyman-alpha (Lya) line from galaxies and the escape of ionising photons. We analyse the Lya spectra of eight LCEs of the local Universe observed with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope (our five leakers and three galaxies from the litterature), and compare their strengths and shapes to the theoretical criteria and comparison samples of local galaxies: the Lyman Alpha Reference Survey, Lyman Break Analogs, Green Peas, and the high-redshift strong LyC leaker Ion2. Our LCEs are found to be strong Lya emitters, with high equivalent widths, EW(Lya)> 70 {\\AA}, and large Lya escape fractions, fesc(Lya) > 20%. The Lya prof...

  7. Lyman-alpha Blobs Like Company : The Discovery of A Candidate 100 kpc Lyman-alpha Blob Near to A Radio Galaxy with A Giant Lyman-alpha halo, B3 J2330+3927 at z=3.1

    CERN Document Server

    Matsuda, Y; Morimoto, N; Smail, Ian; De Breuck, C; Ohta, K; Kodama, T; Inoue, A K; Hayashino, T; Kousai, K; Nakamura, E; Horie, M; Yamada, T; Kitamura, M; Saitô, T; Taniguchi, Y; Tanaka, I; Hibon, P

    2009-01-01

    We present the discovery of a candidate of giant radio-quiet Lyman-alpha (Lya) blob (RQLAB) in a large-scale structure around a high-redshift radio galaxy (HzRG) lying in a giant Lya halo, B3 J2330+3927 at redshift z=3.087. We obtained Lya imaging around B3 J2330+3927 with Subaru/Suprime-Cam to search for Lya emitters (LAEs) and absorbers (LAAs) at redshift z=3.09+-0.03. We detected candidate 127 LAEs and 26 LAAs in the field of view of 31' x 24'. We found that B3 J2330+3927 is surrounded by a 130 kpc Lya halo and a large-scale (60 x 20 comoving Mpc) filamentary structure. The large-scale structure contains one prominent local density peak with an overdensity of greater than 5, which is 8' (15 comoving Mpc) away from B3 J2330+3927. In this peak, we discovered a candidate 100 kpc RQLAB. The existence of both types of Lya nebulae in the same large-scale structure suggests that giant Lya nebulae need special large-scale environments to form. On smaller scales, however, the location of B3 J2330+3927 is not a sign...

  8. The Lyman-alpha luminosity function at z=5.7-6.6 and the steep drop of the faint end: implications for reionization

    CERN Document Server

    Santos, Sérgio; Matthee, Jorryt

    2016-01-01

    We present new results from the widest narrow band survey search for Lyman-alpha (Lya) emitters at z=5.7, just after reionization. We survey a total of 7 deg$^2$ spread over the COSMOS, UDS and SA22 fields. We find over 11,000 line emitters, out of which 514 are robust Lya candidates at z=5.7 within a volume of 6.3x10$^6$ Mpc$^3$. Our Lya emitters span a wide range in Lya luminosities, from faint to bright (L$_{\\rm Ly\\alpha}\\sim10^{42.5-44}$ erg s$^{-1}$) and rest-frame equivalent widths (EW$_0$~25-1000 \\AA) in a single, homogeneous data-set. By combining all our fields we find that the faint end slope of the z=5.7 Lya luminosity function is very steep, with $\\alpha=-2.3^{+0.4}_{-0.3}$. We also present an updated z=6.6 Lya luminosity function, based on comparable volumes and obtained with the same methods, which we directly compare with that at z=5.7. We find a significant decline of the number density of faint Lya emitters from z=5.7 to z=6.6 (by $0.5\\pm0.1$ dex), but no evolution at the bright end/no evolut...

  9. A New Constraint on the Ly$\\alpha$ Fraction of UV Very Bright Galaxies at Redshift 7

    CERN Document Server

    Furusawa, Hisanori; Kobayashi, Masakazu A R; Dunlop, James S; Shimasaku, Kazuhiro; Takata, Tadafumi; Sekiguchi, Kazuhiro; Naito, Yoshiaki; Furusawa, Junko; Ouchi, Masami; Nakata, Fumiaki; Yasuda, Naoki; Okura, Yuki; Taniguchi, Yoshiaki; Yamada, Toru; Kajisawa, Masaru; Fynbo, Johan P U; Fevre, Olivier Le

    2016-01-01

    We study the extent to which very bright (-23.0 50 Angstrom, which we estimate to be < 0.23. This result may indicate a weak trend where the fraction of strong Lya emitters ceases to rise, and possibly falls between z~6 and z~7. Our results also leave open the possibility that strong Lya may still be more prevalent in the brightest galaxies in the reionization era than their fainter counterparts. A larger spectroscopic sample of galaxies is required to derive a more reliable constraint on the neutral hydrogen fraction at z~7 based on the Lya fraction in the bright galaxies.

  10. Disease: H00197 [KEGG MEDICUS

    Lifescience Database Archive (English)

    Full Text Available H00197 Adenylosuccinate lyase deficiency Adenylosuccinate lyase deficiency is an au...ion and most patients have seizures. Inherited metabolic disease; Nervous system disease hsa00230(158) Purin...e metabolism hsa00250(158) Alanine, aspartate and glutamate metabolism ADSL; adenylosuccinate lyas... Spiegel EK, Colman RF, Patterson D Adenylosuccinate lyase deficiency. Mol Genet ...Metab 89:19-31 (2006) PMID:11392513 Ciardo F, Salerno C, Curatolo P Neurologic aspects of adenylosuccinate lyas

  11. Sr、Mg与Fe复合掺杂镓酸镧基离子导体的制备与电性能研究%STUDY ON PREPARATION AND ELECTRICAL PROPERTY OF COMPOSITELY DOPED OXIDE La1-xSrxGa1-yMgyO3-α

    Institute of Scientific and Technical Information of China (English)

    王志奇; 赵捷; 包俊成; 马叙; 李建平

    2007-01-01

    探讨了采用固相反应法合成碱土金属Sr、Mg与过渡金属Fe复合掺杂的镓酸镧基ABO3型氧化物La0.8Sr0.2Ga0.75Mg0.20Fe0.05O2.815(LSGMF);利用热分析仪、EDS、XRD、SEM、直流四端子法等对LSGMF复合氧化物的形成过程、微区成分、晶体结构、显微组织及导电性等进行研究.分析表明:样品的烧结温度不能低于1300℃;EDS结果证实合成的LSGMF样品中杂质元素很少,纯度较高;XRD分析表明:经1350℃烧结合成的LSGMF样品中出现了LaSrGa3O7和LaSrGaO4等杂相,而经1400℃烧结则获得了单一正交钙钛矿结构;电性能测试结果表明:在400-850 ℃温度区间,其电导率与温度的关系符合Arrhenius定律,说明合成的复合氧化物LSGMF为氧离子导体,且离子迁移活化能0.6656eV(<1eV);Sr、Mg和Fe复合掺杂氧化物LSGMF与仅Sr、Mg双掺杂氧化物LSGM相比具有更高的离子电导率,说明少量过渡金属Fe的掺杂,可提高离子电导率.

  12. Spectroscopic Confirmation of Three z-Dropout Galaxies at z = 6.844 - 7.213: Lyman Alpha Demography of z ~ 7 Galaxies

    CERN Document Server

    Ono, Yoshiaki; Mobasher, Bahram; Dickinson, Mark; Penner, Kyle; Shimasaku, Kazuhiro; Weiner, Benjamin J; Kartaltepe, Jeyhan S; Nakajima, Kimihiko; Nayyeri, Hooshang; Stern, Daniel; Kashikawa, Nobunari; Spinrad, Hyron

    2011-01-01

    We present the results of our ultra-deep Keck/DEIMOS spectroscopy of z-dropout galaxies in the SDF and GOODS-N. For 3 out of 11 objects, we detect an emission line at ~ 1um with a signal-to-noise ratio of ~ 10. The lines show asymmetric profiles with high weighted skewness values, consistent with being Lya, yielding redshifts of z=7.213, 6.965, and 6.844. Specifically, we confirm the z=7.213 object in two independent DEIMOS runs with different spectroscopic configurations. The z=6.965 object is a known Lya emitter, IOK-1, for which our improved spectrum at a higher resolution yields a robust skewness measurement. The three z-dropouts have Lya fluxes of 3 x 10^-17 erg s^-1 cm^-2 and rest-frame equivalent widths EW_0^Lya = 33-43A. Based on the largest spectroscopy sample of 43 z-dropouts that is the combination of our and previous data, we find that the fraction of Lya-emitting galaxies (EW_0^Lya > 25A) is low at z ~ 7; 17 +- 10% and 24 +- 12% for bright (Muv ~= -21) and faint (Muv ~= -19.5) galaxies, respectiv...

  13. The effect of dust geometry on the Lyman-alpha output of galaxies

    CERN Document Server

    Scarlata, C; Teplitz, H I; Panagia, N; Hayes, M; Siana, B; Rau, A; Francis, P; Caon, A; Pizzella, A; Bridge, C

    2009-01-01

    We present the optical spectroscopic follow-up of 31 z=0.3 Lyman-alpha (Lya) emitters, previously identified by Deharveng et al. (2008). We find that 17% of the Lya emitters have line ratios that require the hard ionizing continuum produced by an AGN. The uniform dust screen geometry traditionally used in studies similar to ours is not able to simultaneously reproduce the observed high Lya/Halpha and Halpha/Hbeta line ratios. We consider different possibilities for the geometry of the dust around the emitting sources. We find that also a uniform mixture of sources and dust does not reproduce the observed line ratios. Instead, these are well reproduced by a clumpy dust screen. This more realistic treatment of the geometry results in extinction corrected (Lya/Halpha)_C values consistent with Case B recombination theory, whereas a uniform dust screen model would imply values (Lya/Halpha)_C higher than 8.7. Our analysis shows that there is no need to invoke "ad-hoc" multi phase media in which the Lya photons only...

  14. HST/ACS Lyman alpha imaging of the nearby starburst ESO338-IG04

    CERN Document Server

    Hayes, M; Mas-Hesse, J M; Kunth, D; Leitherer, C; Petrosian, A

    2005-01-01

    ESO338-IG04 is a well known, local, luminous Blue Compact Galaxy. It has a complex morphology and contains a central young starburst with compact young star clusters. The galaxy was imaged using HST/ACS in the Lyman alpha line and continuum. Using the Starburst99 synthetic spectra and other imaging data from HST/WFPC2 we developed a technique that allows us to make the first photometrically valid continuum subtraction for the LYa line. Our results are in qualitative agreement with the models of LYa escape being regulated by kinematical properties of the interstellar medium. The line-only image shows LYa in both emission and absorption. Notably, emission is seen from central bright young clusters and is in spatial agreement with the features present in a longslit spectrum taken with HST/STIS. Diffuse LYa emission regions are seen surrounding the central starburst where photons escape after one or more resonant scatterings in HI. These regions dominate the total LYa output. Photometry reveals a total LYa flux o...

  15. The VIMOS Ultra-Deep Survey (VUDS): fast increase of the fraction of strong Lyman alpha emitters from z=2 to z=6

    CERN Document Server

    Cassata, P; Fevre, O Le; Lemaux, B; Garilli, B; Brun, V Le; Maccagni, D; Pentericci, L; Thomas, R; Vanzella, E; Zamorani, G; Zucca, E; Amorin, R; Bardelli, S; Capak, P; Cassara', L; Castellano, M; Cimatti, A; Cuby, J G; Cucciati, O; de la Torre, S; Durkalec, A; Fontana, A; Giavalisco, M; Grazian, A; Hathi, N P; Ilbert, O; Moreau, C; Paltani, S; Ribeiro, B; Salvato, M; Schaerer, D; Scodeggio, M; Sommariva, V; Talia, M; Taniguchi, Y; Tresse, L; Vergani, D; Wang, P W; Charlot, S; Contini, T; Fotopoulou, S; Lopez-Sanjuan, C; Mellier, Y; Scoville, N

    2014-01-01

    Aims. The aim of this work is to constrain the evolution of the fraction of Lya emitters among UV selected star forming galaxies at 2 25A to increase from 5% at z=2 to 30% at z=6, with the increase being relatively stronger beyond z=4. We observe no difference, for the narrow range of UV luminosities explored in this work, between the fraction of strong Lya emitters among galaxies fainter or brighter than M*, although the fraction for the FUV faint galaxies evolves faster, at 2Lya): generally galaxies with high fesc(Lya) have also small amounts of dust (and viceversa). However, when the dust content is low (E(B-V)<0.05) we observe a very broad range of fesc(Lya), ranging from 10^-3 to 1. This implies that the dust alone is not the only regulator of the amount of escaping Lya photons.

  16. Adult exposures from MDCT including multiphase studies: first Italian nationwide survey

    Energy Technology Data Exchange (ETDEWEB)

    Palorini, Federica; Origgi, Daniela [Fisica Sanitaria Istituto Europeo di Oncologia, Milan (Italy); Granata, Claudio [UOC di Radiologia Istituto Giannina Gaslini, Genoa (Italy); Matranga, Domenica [Universita degli Studi di Palermo, Dipartimento di Scienze per la Promozione della Salute e Materno-infantile ' ' G. D' Alessandro' ' , Palermo (Italy); Salerno, Sergio [Policlinico Universita di Palermo, Dipartimento di Scienze Radiologiche, Palermo (Italy)

    2014-02-15

    To evaluate the radiation dose in routine multidetector computed tomography (MDCT) examinations in Italian population. This was a retrospective multicentre study included 5,668 patients from 65 radiology departments who had undergone common CT protocols: head, chest, abdomen, chest-abdomen-pelvis (CAP), spine and cardiac. Data included patient characteristics, CT parameters, volumetric CT dose index (CTDI{sub vol}) and dose length product (DLP) for each CT acquisition phase. Descriptive statistics were calculated, and a multi-regression analysis was used to outline the main factors affecting exposure. The 75th percentiles of CTDI{sub vol} (mGy) and DLP (mGy cm) for whole head were 69 mGy and 1,312 mGy cm, respectively; for chest, 15 mGy and 569 mGy cm; spine, 42 mGy and 888 mGy cm; cardiac, 7 mGy and 131 mGy cm for calcium score, and 61 mGy and 1,208 mGy cm for angiographic CT studies. High variability was present in the DLP of abdomen and CAP protocols, where multiphase examinations dominated (71 % and 73 % respectively): for abdomen, 18 mGy, with 555 and 920 mGy cm in abdomen and abdomen-pelvis acquisitions respectively; for CAP, 17 mGy, with 508, 850 and 1,200 mGy cm in abdomen, abdomen-pelvis and CAP acquisitions respectively. The results of this survey could help in the definition of updated diagnostic reference levels (DRL). (orig.)

  17. High-Throughput Analysis of Dynamic Gene Expression Associated with Sleep Deprivation and Recovery Sleep in the Mouse Brain

    Science.gov (United States)

    2006-12-01

    Additional regions: Dorsal dentate gyrus dDG Dorsal CA3 dCA3 CA1 CA1 Central nucleus of amygdala CEA 14 Basolateral... Bdnf 2 NM_007540 MGI:88145 cholecystokinin Cck 9 NM_031161 MGI:88297 choline acetyltransferase Chat 14 NM_009891 MGI:88392 cholinergic receptor

  18. Distribution of Absorbed Doses to the Important Organs of Head and Neck Region in Panoramic Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byeong Sam; Choi, Karp Sick [Dept. of Dental Radiology, College of Dentistry, Kyungpook National University, Deagu (Korea, Republic of); Kim, Chin Soo [Dept. of Oral and Maxillofacial Surgery, College of Dentistry, Kyungpook National University, Deagu (Korea, Republic of)

    1990-08-15

    The purpose of this study was to estimate the distribution of absorbed doses of each important organs of head and neck region in panoramic radiography. Radiation dosimetry at internal anatomic sites and skin surfaces of phantom (RT-210 Humanoid Head and Neck Section R) was performed with lithium fluoride (TLD-100R) thermoluminescent dosimeters according to change of kilovoltage (65 kVp, 75 kVp and 85 kVp) with 4 miliamperage and 20 second exposure time. The results obtained were as follows; Radiation absorbed doses of internal anatomic sites were presented the highest does of 1.04 mGy, 1.065 mGy and 2.09 mGy in nasopharynx, relatively high doses of 0.525 mGy, 0.59 mGy and 1.108 mGy in deep lobe of parotid gland, 0.481 mGy, 0.68 mGy and 1.191 mGy in submandibular gland. But there were comparatively low doses of 0.172 mGy and 0.128 mGy in eyes and thyroid gland that absorbed dose was estimated at 85kVp. Radiation absorbed doses of skin surfaces were presented the highest doses of 1.263 mGy, 1.538 mGy and 2.952 mGy in back side of first cervical vertebra and relatively high doses of 0.267 mGy, 0.401 mGy and 0.481 mGy in parotid gland. But there were comparatively low doses of 0.057 mGy, 0.068 mGy and 0.081 mGy in philtrum and 0.059 mGy in middle portion of chin that absorbed dose was estimated at 85 kVp. According to increase of kilovoltage, the radiation absorbed doses were increased 1.1 times when kilovoltage changes from 65 kVp to 75 kVp and 1.9 times when kilovoltage changes from 75 kVp to 85 kVp at internal anatomic sites. According to increase of kilovoltage, the radiation absorbed doses were increased 1.3 times when kilovoltage changes from 65 kVp to 75 kVp and 1.6 times when kilovoltage changes from 75 kVp to 85 kVp at skin surfaces.

  19. Quasars Probing Quasars IV: Joint Constraints on the Circumgalactic Medium from Absorption and Emission

    CERN Document Server

    Hennawi, Joseph F

    2013-01-01

    We have constructed a sample of 29 close projected quasar pairs where the background quasar spectrum reveals absorption from optically thick HI gas associated with the foreground quasar. These unique sightlines allow us to study the quasar circumgalactic medium (CGM) in absorption and emission simultaneously, because the background quasar pinpoints large concentrations of gas where Ly-a emission, resulting from quasar-powered fluorescence, resonant Ly-a scattering, and/or cooling radiation, is expected. A sensitive slit-spectroscopic search (1-sigma limits of SB_Lya ~= 3e-18 erg/s/cm^2/arcsec^2) for diffuse Ly-a emission in the environments of the foreground quasars is conducted. We fail to detect large-scale ~ 100 kpc Ly-a emission, either at the location of the optically thick absorbers or in the foreground quasar halos, in all cases except a single system. We interpret these non-detections as evidence that the gas detected in absorption is shadowed from the quasar UV radiation due to obscuration effects, w...

  20. In Search of the Dark Ages -- An Experimental Challenge

    CERN Document Server

    Bland-Hawthorn, J

    2004-01-01

    Most direct source detections beyond z~7 are likely to arise from wide-field narrowband surveys of Ly-a emission in the J band. For this to be true, the Ly-a emission must somehow escape from compact star-forming regions (CSR) presumably associated with massive haloes. Since the Ly-a escape fraction is <10% from an emitting region of size roughly 1 kpc, these objects will be difficult to find and hard to detect. For CSR sources, existing large-format IR arrays are close to ideal in terms of their noise characteristics for conducting "wide-field" narrowband surveys where pixel sizes are 0.1" or larger. However, we stress that Ly-a can also arise from external large-scale shocks (ELS) due to starburst winds, powered by CSRs, ploughing into gas actively accreting onto the dark halo. The winds effectively carry energy from the dense, dusty environment of a starburst into lower density regions, where the escape probability for Ly-a photons is greater. ELS emission is expected to be considerably more clumpy (<...

  1. Far-UV Emission Properties of FR1 Radio Galaxies

    CERN Document Server

    Danforth, Charles W; France, Kevin; Begelman, Mitchell C

    2016-01-01

    The power mechanism and accretion geometry for low-power FR1 radio galaxies is poorly understood in comparison to Seyfert galaxies and QSOs. In this paper, we use the diagnostic power of the Lya recombination line observed using the Cosmic Origins Spectrograph aboard HST to investigate the accretion flows in three well-known, nearby FR1s: M87, NGC4696, and HydraA. The Lya emission line's luminosity, velocity structure, variability and the limited knowledge of its spatial extent provided by COS are used to assess conditions within a few parsecs of the SMBH in these radio-mode AGN. We observe strong Lya emission in all three objects with similar total luminosity to that seen in BL Lacertae objects. M87 shows a complicated emission line profile in Lya which varies spatially across the COS aperture as well as temporally over several epochs of observation. Over the same observing epochs the UV continuum was seen to not vary, making it unlikely that the observed UV continuum is the ionizing source for Lya. In both ...

  2. Lyman-Alpha Emitting Galaxies as a Probe of Reionization: Large-Scale Bubble Morphology and Small-Scale Absorbers

    CERN Document Server

    Kakiichi, Koki; Ciardi, Benedetta; Graziani, Luca

    2015-01-01

    The visibility of LyA emitting galaxies during the Epoch of Reionization is controlled by both diffuse HI patches in large-scale bubble morphology and small-scale absorbers. To investigate the impact on LyA photons, we apply a novel combination of analytic and numerical calculations to three scenarios: (i) the `bubble' model, where only diffuse HI outside ionized bubbles is present; (ii) the `web' model, where HI exists only in overdense self-shielded gas; and (iii) the more realistic 'web-bubble' model, which contains both. Our analysis confirms that there is a degeneracy between the ionization structure of the intergalactic medium (IGM) and the HI fraction inferred from LyA surveys, as the three models suppress LyA flux equally with very different HI fractions. We argue that a joint analysis of the LyA luminosity function and the rest-frame equivalent width distribution/LyA fraction can break this degeneracy and provide constraints on the reionization history and its topology. We further show that constrain...

  3. Discovery of Massive, Mostly Star-formation Quenched Galaxies with Extremely Large Lyman-alpha Equivalent Widths at z ~ 3

    CERN Document Server

    Taniguchi, Yoshiaki; Kobayashi, Masakazu A R; Nagao, Tohru; Shioya, Yasuhiro; Scoville, Nick Z; Sanders, David B; Capak, Peter L; Koekemoer, Anton M; Toft, Sune; McCracken, Henry J; Fevre, Olivier Le; Tasca, Lidia; Sheth, Kartik; Renzini, Alvio; Lilly, Simon; Carollo, Marcella; Kovac, Katarina; Ilbert, Olivier; Schinnerer, Eva; Fu, Hai; Tresse, Laurence; Griffiths, Richard E; Civano, Francesca

    2015-01-01

    We report a discovery of 6 massive galaxies with both extremely large Lya equivalent width and evolved stellar population at z ~ 3. These MAssive Extremely STrong Lya emitting Objects (MAESTLOs) have been discovered in our large-volume systematic survey for strong Lya emitters (LAEs) with twelve optical intermediate-band data taken with Subaru/Suprime-Cam in the COSMOS field. Based on the SED fitting analysis for these LAEs, it is found that these MAESTLOs have (1) large rest-frame equivalent width of EW_0(Lya) ~ 100--300 A, (2) M_star ~ 10^10.5--10^11.1 M_sun, and (3) relatively low specific star formation rates of SFR/M_star ~ 0.03--1 Gyr^-1. Three of the 6 MAESTLOs have extended Ly$\\alpha$ emission with a radius of several kpc although they show very compact morphology in the HST/ACS images, which correspond to the rest-frame UV continuum. Since the MAESTLOs do not show any evidence for AGNs, the observed extended Lya emission is likely to be caused by star formation process including the superwind activit...

  4. HST/COS Observations of the Ly alpha Forest toward the BL Lac Object 1ES1553+113

    CERN Document Server

    Danforth, Charles W; Stocke, John T; Shull, J Michael; Yao, Yangsen

    2010-01-01

    We present new far-ultraviolet spectra from the Cosmic Origins Spectrograph (HST/COS) of the BL Lac object 1ES1553+113 covering the wavelength range 1135-1795 A. The data show a smooth continuum with a wealth of narrow absorption features arising in the ISM and IGM. These features include 41 Lya absorbers at 00.6 for the strongest component of the absorber complex. Galaxy redshift surveys show a number of massive galaxies at approximately the same redshift as this absorption complex, suggesting that it arises in a large-scale galaxy filament. As one of the brightest extragalactic X-ray and gamma-ray sources, 1ES1553+113 is of great interest to the high-energy astrophysics community. With no intrinsic emission or absorption features, 1ES1553+113 has no direct redshift determination. We use intervening Lya absorbers to place a direct limit on the redshift: z_em>0.395 based on a confirmed Lya+OVI absorber and z_em>0.433 based on a single-line detection of Lya. COS/FUV data are only sensitive to Lya absorbers at ...

  5. The Lyman-alpha Reference Sample: I. Survey outline and first results for Markarian 259

    CERN Document Server

    Östlin, Göran; Duval, Florent; Sandberg, Andreas; Rivera-Thorsen, Thoger; Marquart, Thomas; Orlitova, Ivana; Adamo, Angela; Melinder, Jens; Guaita, Lucia; Atek, Hakim; Cannon, John M; Gruyters, Pieter; Herenz, Edmund Christian; Kunth, Daniel; Laursen, Peter; Mas-Hesse, J Miguel; Micheva, Genoveva; Pardy, Hector Oti-Floranes Stephen A; Roth, Martin M; Schaerer, Daniel; Verhamme, Anne

    2014-01-01

    The Lyman-alpha reference sample (LARS) is a program with the Hubble Space Telescope (HST) that provides a sample of local universe laboratory galaxies in which to study the astrophysics of the visibility and strength of the Lyman-alpha (Lya) line of hydrogen. This article presents an overview of the survey, its selection function and HST imaging observations. The sample was selected from the GALEX+SDSS catalogue at z=0.028-0.19, in order to allow Lya to be captured with combinations of long pass filters in the Solar Blind Channel (SBC) of HST/ACS. In addition, LARS utilises Halpha and Hbeta narrow, and U, B, i broad-band imaging with ACS and WFC3. In order to study galaxies in which large numbers of Lya photons are produced we demanded an Halpha equivalent width > 100{\\AA}. The sample of 14 galaxies covers far UV (FUV) luminosities that overlaps with those of high-z Lya emitters and Lyman Break Galaxies (LBGs). We present the reduction steps used to obtain the Lya images, including our LARS eXtraction softwa...

  6. The environments of Ly$\\alpha$ blobs I: Wide-field Ly$\\alpha$ imaging of TN J1338-1942, a powerful radio galaxy at $z\\simeq 4.1$ associated with a giant Ly$\\alpha$ nebula

    CERN Document Server

    Saito, Tomoki; Lacey, Cedric G; Smail, Ian; Orsi, Alvaro; Baugh, Carlton M; Inoue, Akio K; Tanaka, Ichi; Yamada, Toru; Ohta, Kouji; De Breuck, Carlos; Kodama, Tadayuki; Taniguchi, Yoshiaki

    2014-01-01

    We present wide-field Lya imaging observations of the field around TN J1338-1942, a powerful radio galaxy associated with an extended Lya nebula (>100 kpc) at z=4.11, with Subaru Prime-focus Camera to probe the environment of the radio galaxy. We used a sample of Lya emitters (LAEs) down to the Lya luminosity of $\\log(L_{\\rm Lya}\\rm [erg\\, s^{-1}])\\sim 42.8$ to measure the galaxy density of this field, calibrating by direct comparison with a control sample in a blank field taken with the same instrument. We found that the radio galaxy resides in a region with a peak overdensity of $\\delta_{\\rm LAE}=3.1\\pm 0.5$, after being smoothed on $8\\, h^{-1}$ Mpc scales on the sky and $160\\, h^{-1}$ Mpc along the line of sight (both in comoving coordinates). Adjacent to this overdense region, we found a highly underdense region where virtually no LAEs are detected. We used a semi-analytical model of LAEs derived from the Millennium Simulation to compare our results with theoretical predictions. This comparison suggests t...

  7. Cosmological parameters from combining the Lyman-alpha forest with CMB, galaxy clustering and SN constraints

    CERN Document Server

    Seljak, U; McDonald, P; Seljak, Uros; Slosar, Anze; Donald, Patrick Mc

    2006-01-01

    We combine the Ly-alpha forest power spectrum (LYA) from the Sloan Digital Sky Survey (SDSS) and high resolution spectra with the cosmic microwave background (CMB) including 3-year WMAP, supernovae (SN) and galaxy clustering constraints to derive new constraints on cosmological parameters. The existing LYA power spectrum analysis is supplemented by constraints on the mean flux decrement derived using a principal component analysis for quasar continua, which improves the LYA constraints on the linear power. The joint analysis reduces the errors on all parameters and prefers the simplest 6 parameter cosmological model. We find some tension between the WMAP3 and LYA power spectrum amplitudes, at the ~2 sigma level, which is partially alleviated by the inclusion of other observations: we find sigma_8=0.85+-0.02 compared to sigma_8=0.80+-0.03 without LYA. For the slope we find n_s=0.965+-0.012. We find no evidence for running of the spectral index, dn/dln k=-0.020+-0.012, in agreement with inflation. The limits on...

  8. Observing Supernova 1987A with the Refurbished Hubble Space Telescope

    CERN Document Server

    France, Kevin; Heng, Kevin; Kirshner, Robert; Challis, Peter; Bouchet, Patrice; Crotts, Arlin; Dwek, Eli; Fransson, Claes; Garnavich, Peter; Larsson, Josefin; Lawrence, Stephen; Lundqvist, Peter; Panagia, Nino; Pun, Chun; Smith, Nathan; Sollerman, Jesper; Sonneborn, George; Stocke, John; Wang, Lifan; Wheeler, Craig

    2010-01-01

    Observations with the Hubble Space Telescope (HST), conducted since 1990, now offer an unprecedented glimpse into fast astrophysical shocks in the young remnant of supernova 1987A. Comparing observations taken in 2010 using the refurbished instruments on HST with data taken in 2004, just before the Space Telescope Imaging Spectrograph failed, we find that the Ly-a and H-a lines from shock emission continue to brighten, while their maximum velocities continue to decrease. We observe broad blueshifted Ly-a, which we attribute to resonant scattering of photons emitted from hotspots on the equatorial ring. We also detect NV~\\lambda\\lambda 1239,1243 A line emission, but only to the red of Ly-A. The profiles of the NV lines differ markedly from that of H-a, suggesting that the N^{4+} ions are scattered and accelerated by turbulent electromagnetic fields that isotropize the ions in the collisionless shock.

  9. AcEST: DK962771 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TN Threonine aldolase OS=Thermoanaerobacter ... 199 2e-49 tr|B7R6Z2|B7R6Z2_9THEO Beta-eliminating lyase supe...|B0K216|B0K216_THEPX Aromatic amino acid beta-eliminating lyas... 196 1e-48 tr|B0KDB4|B0KDB4_THEP3 Aromatic amino acid beta-eliminati...ng lyas... 195 2e-48 tr|Q9K7S6|Q9K7S6_BACHD L-allo-threo

  10. On the expected value and distribution function of the first exit time for the Polya-Aeppli process

    Science.gov (United States)

    Cakmakyapan, Selen; Ozel, Gamze

    2013-10-01

    lya-Aeppli process is a particular case of classical compound Poisson process where the contribution of each term is distributed according to the geometric distribution and is used for describing clustered data since the Poisson process is insufficient for clustering of events. In this study, the distribution function and expected value of the first exit time are derived for Pólya-Aeppli process. Then, an application based on traffic accidents in Groningen are given and expected times obtained for some time-independent boundaries using R project.

  11. The infant Milky Way

    CERN Document Server

    Salvadori, Stefania

    2012-01-01

    We investigate the physical properties of the progenitors of today living Milky Way-like galaxies that are visible as Damped Lya Absorption systems and Lya Emitters at higher redshifts (z ~ 2.3,5.7). To this aim we use a statistical merger-tree approach that follows the formation of the Galaxy and its dwarf satellites in a cosmological context, tracing the chemical evolution and stellar population history of the progenitor halos. The model accounts for the properties of the most metal-poor stars and local dwarf galaxies, providing insights on the early cosmic star-formation. Fruitful links between Galactic Archaeology and more distant galaxies are presented.

  12. Egy tanúságtevő hitvalló, szolgáló, tudományos és papi pálya lezárult: Petrasevics Nikefor József eperjesi görög katolikus kanonok és tudományos kutató emlékére (1915–2013 - Passed a Wittness of the Faith, Scientist, a Servant of The Lord, True Priest: Nicefor Petrashevich (1915–2013, canon of the Preshov Greek Catholic Eparchy

    Directory of Open Access Journals (Sweden)

    FÖLDVÁRI, Sándor

    2014-03-01

    Full Text Available Decease of the witness of the Faith, a servant of the Lord and a famous researcher of the religious folklore: Nicefor Joseph Petrashevich (1915–2013 distinguished member of the Capitol of Preshov Greek Catholic Eparchy Born in Čukalovce, East-Slovakia (then Csukalóc, Upper-Hungary in 1915 as the sixth of the eleven children in the family of a Greek Catholic bishop, he was inspired by his father and elder brother who served the Lord. He studied in the high school (gymnasium of the Cistercian Order in Eger (Northern Hungary which provided its pupils with knowledge and deep faith. He became a choir-minister of the Uzghorod Bishopric Basilica where he turned to the examination of folklore traditions reflected in the liturgical chants. Apparently, it was his calling and his findings on the Byzantine chants contributed significantly to the understanding of religious folklore. He was known as a gifted composer and singer too. The Greek Catholic Church was banned in the Soviet Union which obtained Subcarpathia after the World War II, and this church was oppressed in Slovakia as well, so he faced a dilemma: to convert to the Ortodox (Pravoslav Christianity and live free, or to remain faithful to the Catholic Church and be persecuted. Moreover, he was a coelebs, a priest who did not have a wife (despite the fact that Greek Catholic priests are allowed to have families. Consequently, he could have been elected as bishop, as the higher ranks in the Byzantine Churches are open for monks. The communist authorities offered Pope Nicefor the episcopate of the Slovak Ortodox Church, if he converted to the Ortodoxy. He refused it: “my head does not accept the mithra (bishops’ crone by leaving my Catholic faith” –he said. As a result, he was imprisoned for more than two years in Slovakia. Later he came to Hungary where could not serve as a parochial priest, but worked as cantor or helping pope in various places and in centres of pilgrimage where performed the liturgy in Church Slavonic which he sang excellently. Continuing his researches in the folk sings in the liturgy and the local traditions of the liturgical chants, he gained a small grant of the Soros Foundation in 1986 and delivered lectures for two semesters at the Department of the Folklore at the Eötvös University in Budapest in 1988–89. His papers have been par tia l ly published, but most of t hem are still preserved as manuscripts in the Institute of Musicology at the Hungarian Academy of Sciences, or even in unknown places worldwide, as he sent his works to his brothers-in-faith to the United States. In his eighties, instead of enjoying the golden days of ageing, he moved to Slovakia in order to serve as a pastor who spoke both Slovakian and Hungarian as mother tongues. He was buried in Szikszó, Hungary where the Greek Catholic Bishop of Preshov and approximately forty popes from Ukraine, Hungary and Slovakia commemorated him on 20 July 2013. Church historians and folklorists honoured his memory as a researcher with a conference on 4 October 2013 in Szikszó. Proceedings are to be published next year. A memorial website about him is open for bloggers: https://www.facebook.com/groups/Petrasevic.Nikefor.spomienky

  13. A study on compression paddle materials to reduce radiation exposure dose during mammography: PC and PMMA and carbon

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Dong Hee [Dept. of Radiological Science, Far east University, Eumsung (Korea, Republic of); Jung, Hong Ryang [Dept. of Radiological Science, Hanseo University, Seosan (Korea, Republic of)

    2015-06-15

    This study was designed the band material in order to reduce the exposure pressure of the breast and the material was measured of Radiolucent and radiation properties with a radiation materials of PC, PMMA, Carbon. Also the image quality by image analysis to obtain the following results are below: Unfors Xi dosimetry using radiation transmittance when the results of 8.353 mGy is measured after removal of the cuff, the PC 6.308 mGy, PMMA 6.223 mGy, Carbon 7.218 mGy were measured respectively. Semi-layer PC 0.375 mmAl, PMMA 0.370 mmAl, with Carbon 0.360 mmAl Carbon, PC, PMMA was higher radiation properties and transparency in order. InLight / OSL NanoDotTM dosimeter was used in the cuff and then removed by placing the dosimeter measured results center on 1.143 mGy, at the edge 12.56 mGy, on the central PC 8.990 mGy, at the edge 10.291 mGy, PMMA center on 8.391 mGy , the edge 9.654 mGy, on Carbon center 9.581 mGy, 11.313 mGy were measured at the edge of Carbon, PC, PMMA showed a high permeability in order. Image Pixel average J is then removed from the cuff 976.655, PC 831.032, PMMA 819.069, Carbon 897.118 Carbon, PC, PMMA was measured by high order.

  14. Lyman-alpha Cooling Emission from Galaxy Formation

    CERN Document Server

    Faucher-Giguere, C -A; Dijkstra, M; Hernquist, L; Zaldarriaga, M

    2010-01-01

    Recent studies have shown that galaxies accrete most of their baryons via the cold mode, from streams with temperatures T~10^4-10^5 K. At these temperatures, the streams should radiate primarily in Lya and have therefore been proposed as a model to power the Lya blobs and other high-redshift Lya sources. We introduce a new Lya radiative transfer code, aRT, and apply it to cosmological hydrodynamical simulations. We address physical and numerical issues that are critical to making accurate predictions for the cooling luminosity, but that have been mostly neglected or treated simplistically so far. We highlight the importance of self-shielding and of properly treating sub-resolution models in simulations. Most existing simulations do not self-consistently incorporate these effects, which can lead to order-of-magnitude errors in the predicted cooling luminosity. Using a combination of post-processing ionizing radiative transfer and re-simulation techniques, we develop an approximation to the consistent evolution...

  15. HeII emission in Lyman-alpha nebulae: AGN or cooling radiation?

    CERN Document Server

    Scarlata, C; Teplitz, H I; Bridge, C; Francis, P; Palunas, P; Siana, B; Williger, G M; Woodgate, B

    2009-01-01

    We present a study of an extended Lyman-alpha (Lya) nebula located in a known overdensity at z~2.38. The data include multiwavelength photometry covering the rest-frame spectral range from 0.1 to 250um, and deep optical spectra of the sources associated with the extended emission. Two galaxies are associated with the Lya nebula. One of them is a dust enshrouded AGN, while the other is a powerful starburst, forming stars at >~600 Msol/yr. We detect the HeII emission line at 1640A in the spectrum of the obscured AGN, but detect no emission from other highly ionized metals (CIV or NV) as is expected from an AGN. One scenario that simultaneously reproduces the width of the detected emission lines, the lack of CIV emission, and the geometry of the emitting gas, is that the HeII and the Lya emission are the result of cooling gas that is being accreted on the dark matter halo of the two galaxies, Ly1 and Ly2. Given the complexity of the environment associated with our Lya nebula it is possible that various mechanism...

  16. Large Scale Structure in Absorption: Gas within and around Galaxy Voids

    CERN Document Server

    Tejos, Nicolas; Crighton, Neil H M; Theuns, Tom; Altay, Gabriel; Finn, Charles W

    2012-01-01

    We investigate the properties of the HI Ly-a absorption systems (Ly-a forest) within and around galaxy voids at z99% c.l.) of Ly-a systems at the edges of galaxy voids with respect to a random distribution, on ~5 h^{-1} Mpc scales. We find no significant difference in the number of systems inside voids with respect to the random expectation. We report differences between both column density (N_{HI}) and Doppler parameter (b_{HI}) distributions of Ly-a systems found inside and at the edge of galaxy voids at the >98% and >90% c.l. respectively. Low density environments (voids) have smaller values for both N_{HI} and b_{HI} than higher density ones (edges of voids). These trends are theoretically expected and also found in GIMIC, a state-of-the-art hydrodynamical simulation. Our findings are consistent with a scenario of at least three types of Ly-alpha: (1) containing embedded galaxies and so directly correlated with galaxies (referred as `halo-like'), (2) correlated with galaxies only because they lie in the s...

  17. Nonparametric Bayes inference for concave distribution functions

    DEFF Research Database (Denmark)

    Hansen, Martin Bøgsted; Lauritzen, Steffen Lilholt

    2002-01-01

    Bayesian inference for concave distribution functions is investigated. This is made by transforming a mixture of Dirichlet processes on the space of distribution functions to the space of concave distribution functions. We give a method for sampling from the posterior distribution using a Pólya urn...

  18. The COS Absorption Survey of Baryon Harbors (CASBaH): Probing the Circumgalactic Media of Galaxies from z = 0 to z = 1.5

    Science.gov (United States)

    Tripp, Todd

    2014-10-01

    In Cycle 17, we obtained high S/N, far-ultraviolet COS spectra of nine QSOs at 0.92 data will be mined for some time, but ultimately the usefulness of the database is limited by the FUV wavelength range of the original observations. To fully exploit these unique HST observations to study the circumgalactic medium during the golden age of star formation (0.5 1800 A) spectroscopy of the same QSOs with STIS and COS to fully cover the H I Lya and Lyman series from z = 0 out to z = z(QSO) and significantly improve the statistics of far-UV lines and diagnostics. With these data we will (1) obtain precise metallicities of the cool CGM with added coverage of H I Lya and Lyman series lines (often not covered in current data at z > 0.5), (2) constrain the metallicity and mass of the warm-hot gas from, e.g, OVI/NeVIII + broad Lya constraints, (3) measure relative abundances (instead of assuming them) using banks of ions accessible only in the far-UV, (4) study absorber redshift evolution with the expanded samples at 0.5 < z < 1.5, (5) obtain more complete and accurate identification of weak lines, which is difficult without constraints on Lya at 0.5 < z < z(QSO), and (6) investigate statistical absorber-galaxy relationships in the epoch of peak star formation.

  19. Riikliku autasu saajaid Välis-Eestis / Heino Nurk

    Index Scriptorium Estoniae

    Nurk, Heino

    2004-01-01

    President Arnold Rüütel annetas iseseisvuspäeva puhul teenetemärgi paljudele eestluse hoidjatele ja Eesti NATOga liitumise toetajatele välismaal: Karl Stephen Altau, Väino Riismandel, Kristi Ranfeldt, Gunnar Paabo - Valgetähe IV klass ; Helmut Kalmann, Lya Karm - Valgetähe V klass ; Rein Puusepp - Kotkaristi III klass

  20. The Luminosity Function of Lyman Alpha Emitting Galaxies and Cosmic Reionisation of Hydrogen

    CERN Document Server

    Dijkstra, M; Haiman, Z; Dijkstra, Mark; Wyithe, Stuart; Haiman, Zoltan

    2006-01-01

    Recent observations imply that the observed number counts of Lyman Alpha (Lya) emitters evolved significantly between z=5.7 and z=6.5. It has been suggested that this evolution was due to a rapid evolution in the ionisation state, and hence transmission of the IGM which caused Lya flux from z=6.5 galaxies to be more strongly suppressed. In this paper we show that the observed evolution can be attributed entirely to the evolution in the mass function of dark matter halos housing the Lya emitters. We place constraints on the evolution of transmission in the IGM between z=6.5 and z=5.7, finding a ratio of ~1.2, which may be accounted for by the evolution of the mean IGM density through cosmic expansion. Using a model for IGM transmission, we demonstrate that Lya emitting galaxies at z=6.5 must be embedded in HII bubbles greater than 35x_HI comoving Mpc in size, where x_HI is the neutral fraction of hydrogen outside the ionised bubbles. The model of Furlanetto et al (2006) may be used to translate this into a low...

  1. Lyman Alpha Emitters in the Hierarchically Clustering Galaxy Formation

    CERN Document Server

    Kobayashi, Masakazu A R; Nagashima, Masahiro

    2007-01-01

    We present a new theoretical model for the luminosity functions (LFs) of Lyman alpha (Lya) emitting galaxies in the framework of hierarchical galaxy formation. We extend a semi-analytic model of galaxy formation that reproduces a number of observations for local galaxies, without changing the original model parameters but introducing a physically-motivated modelling to describe the escape fraction of Lya photons from host galaxies (f_esc). Though a previous study using a hierarchical clustering model simply assumed a constant and universal value of f_esc, we incorporate two new effects on f_esc: extinction by interstellar dust and galaxy-scale outflow induced as a star formation feedback. It is found that the new model nicely reproduces all the observed Lya LFs of the Lya emitters (LAEs) at different redshifts in z ~ 3--6. Our model predicts that galaxies with strong outflows and f_esc ~ 1 are dominant in the observed LFs, which is consistent with available observations while the simple universal f_esc model ...

  2. Cellular recovery in two sub-lines of the L5178Y marine leukaemic lymphoblast cell line differing in their sensitivity to ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    McMillan, T.J.; Eady, J.J.; Peacock, J.H.; Steel, G.G. (Institute of Cancer Research, Sutton (United Kingdom). Surrey Branch)

    1992-01-01

    Cellular recovery was assessed in two sublines of L5178Y murine lymphoma cells of differing radiosensitivity (LY-S and LY-A4) using low dose-rate irradiation and split-dose experiments. No increase in cell survival was observed in the LY-S cell line until the dose-rate was reduced to 2cGy/min, whereas in the LY-A4 cell line 20 cGy/min was low enough to detect changes in survival. The extent of this change, as assessed by dose reduction factors at 2 logs of cell kill, was greater in the LY-A4 cell line. Fitting these data with the incomplete repair model of Thames led to anomalous values for the half-time of repair. In split-dose experiments the maximum observed recovery ratio increased as a function of dose in a manner that is consistent with the linear-quadratic equation. As was found previously with radiosensitive human tumour cells, the LY-S cell line showed more split-dose recovery at any given dose than the LY-A4 cell line. (author).

  3. Continuity of the equilibrium price density and its uses in peak-load pricing

    NARCIS (Netherlands)

    Horsley, A.; Wrobel, A.J.

    2005-01-01

    With L∞ as the commodity space, the equilibrium price density is shown to be a continuous function of the commodity characteristics. The result is based on symmetry ideas from the Hardy-Littlewood-Pólya theory of rearrangements. It includes, but is not limited to, the case of symmetric

  4. Ionizing radiation fluctuations and large-scale structure in the Lyman-alpha forest

    CERN Document Server

    Croft, R A C

    2003-01-01

    We investigate the large-scale inhomogeneities of the hydrogen ionizing radiation field in the Universe at redshift z=3. Using a raytracing algorithm, we simulate a model in which quasars are the dominant sources of radiation. We make use of large scale N-body simulations of a LambdaCDM universe, and include such effects as finite quasar lifetimes and output on the lightcone, which affects the shape of quasar light echoes. We create Lya forest spectra that would be generated in the presence of such a fluctuating radiation field, finding that the power spectrum of the Lya forest can be suppressed by as much as 15 % for modes with k=0.05-1 Mpc/h. This relatively small effect may have consequences for high precision measurements of the Lya power spectrum on larger scales than have yet been published. We also investigate another radiation field probe, the cross-correlation of quasar positions and the Lya forest. For both quasar lifetimes which we simulate (10^7 yr and 10^8 yr), we expect to see a strong decrease ...

  5. Protoplanetary disk shadowing by gas infalling onto the young star AK Sco

    CERN Document Server

    de Castro, Ana I Gomez; France, Kevin; Sytov, Alexey; Bisikalo, Dmitry

    2016-01-01

    Young solar-type stars grow through the accretion of material from the circumstellar disk during pre-main sequence (PMS) evolution. The ultraviolet radiation generated in this process plays a key role in the chemistry and evolution of young planetary disks. In particular, the hydrogen Lyman-alpha line (Lya) etches the disk surface by driving photoevaporative flows that control disk evolution. Using the Hubble Space Telescope, we have monitored the PMS binary star AK Sco during the periastron passage and have detected a drop of the H2 flux by up to 10% lasting 5.9 hours. We show that the decrease of the H2 flux can be produced by the occultation of the stellar Lya photons by a gas stream in free fall from 3 R*. Given the high optical depth of the Lya line, a very low gas column of NH > 5e17 cm-2 suffices to block the Lya radiation without producing noticeable effects in the rest of the stellar spectral tracers.

  6. C IV and He II Line Emission of Lyman Alpha Blobs: Powered by Shock Heated Gas

    CERN Document Server

    Cabot, Samuel H C; Zheng, Zheng

    2016-01-01

    Utilizing {\\it ab initio} ultra-high resolution hydrodynamical simulations, we investigate the properties of the interstellar and circum-galactic medium of Ly$\\alpha$ Blobs (LABs) at $z=3$, focusing on three important emission lines: Ly$\\alpha$ 1216\\AA, \\heii 1640\\AA\\ and \\civ 1449\\AA. Their relative strengths provide a powerful probe of the thermodynamic properties of the gas when confronted with observations. By adjusting the dust attenuation effect using one parameter and matching the observed size-luminosity relation of LABs using another parameter, we show that our simulations can reproduce the observed \\civ/\\lya\\ and \\heii/\\lya\\ ratios adequately. This analysis provides the first successful physical model to account for simultaneously the LAB luminosity function, luminosity-size relation, and the \\civ/Ly$\\alpha$ and \\heii/Ly$\\alpha$ ratios, with only two parameters. The physical underpinning for this model is that, in addition to the stellar component for the \\lya\\ emission, the \\lya\\ and \\civ\\ emission...

  7. Bright and Faint Ends of Ly$\\alpha$ Luminosity Functions at $\\textit{z} = 2$ Determined by the Subaru Survey: Implications for AGN, Magnification Bias, and ISM HI Evolution

    CERN Document Server

    Konno, Akira; Nakajima, Kimihiko; Duval, Florent; Kusakabe, Haruka; Ono, Yoshiaki; Shimasaku, Kazuhiro

    2015-01-01

    We present the Lya luminosity functions (LFs) derived by our deep Subaru narrowband survey that identifies a total of 3,137 Lya emitters (LAEs) at $z = 2.2$ in five independent blank fields. The sample of these LAEs is the largest, to date, and covers a very wide Lya luminosity range of $\\log L_{Ly\\alpha} = 41.7-44.4$ erg s$^{-1}$. We determine the Lya LF at $z = 2.2$ with unprecedented accuracies, and obtain the best-fit Schechter parameters of $L^{*}_{Ly\\alpha} = 5.29^{+1.67}_{-1.13} \\times 10^{42}$ erg s$^{-1}$, $\\phi^{*}_{Ly\\alpha} = 6.32^{+3.08}_{-2.31} \\times 10^{-4}$ Mpc$^{-3}$, and $\\alpha = -1.75^{+0.10}_{-0.09}$ showing a steep faint-end slope. We identify a significant hump at the LF bright end ($\\log L_{Ly\\alpha} > 43.4$ erg s$^{-1}$). Because all of the LAEs in the bright-end hump have (a) bright counterpart(s) either in the X-ray, UV, or radio data, this bright-end hump is not made by gravitational lensing magnification bias but AGNs. These AGNs allow us to derive the AGN UV LF at $z \\sim 2$ dow...

  8. Continuity of the equilibrium price density and its uses in peak-load pricing

    NARCIS (Netherlands)

    Horsley, A.; Wrobel, A.J.

    2005-01-01

    With L∞ as the commodity space, the equilibrium price density is shown to be a continuous function of the commodity characteristics. The result is based on symmetry ideas from the Hardy-Littlewood-Pólya theory of rearrangements. It includes, but is not limited to, the case of symmetric (rearrangemen

  9. Lyman alpha emitting galaxies at high redshift: Direct detection of young galaxies in a young universe

    Science.gov (United States)

    Dawson, Steven Arthur

    An early result of galaxy formation theory was the prediction that the copious ionizing radiation produced in nascent galaxies undergoing their first starbursts should in turn produce a strong Lya emission line. We report on our efforts to detect and characterize primeval galaxies by searching for this expected Lya signature with two observational techniques: serendipitous slit spectroscopy, and narrowband imaging selection. In Part I, we describe our serendipitous slit spectroscopy survey of the Hubble Deep Field and its environs, which resulted in a catalog of 74 spectroscopic redshifts spanning 0.10 5. Follow-up observations at higher resolution resulted in the additional serendipitous detection of a strong Lya-emitting galaxy at z = 5.190 (ES1). At the time of its discovery, ES1 was one of only nine known galaxies at z > 5, and was the sixth most distant known galaxy. The unprecedented spectral purity of the observation offers evidence for a galaxy-scale outflow with a. velocity of v > 300 km s -1 , consistent with wind speeds observed in powerful local starbursts (typically 10 2 to 10 3 km s -1 ), and with simulations of the late- stage evolution of Lya emission in star-forming systems. Our final serendipitous detection is the remarkable source CXOHDFN J123635.6+621424, which is both the highest redshift known spiral galaxy, and a rare example of a high redshift, hard X-ray-emitting Type II AGN. Significantly, all of these results were acquired with no direct allocation of telescope time. In Part II, we report on our implementation of narrowband imaging selection, with which we traded redshift coverage for survey volume, focusing on the systematic study of galaxies at a particular epoch in favor of chasing that rare, most-distant object. This effort resulted in a catalog of 76 z [approximate] 4.5 Lya-emitting galaxies spectroscopically-confirmed in campaigns of Keck/LRIS and Keck/DEIMOS follow-up observations to candidates selected in the Large Area Lyman

  10. Assessment of radiation exposure on a dual-source computed tomography-scanner performing coronary computed tomography-angiography

    Energy Technology Data Exchange (ETDEWEB)

    Kirchhoff, S., E-mail: sonja.kirchhoff@med.uni-muenchen.d [Institute of Clinical Radiology, University Hospital Munich - Grosshadern, Ludwig Maximilians-Universitaet Muenchen, Klinikum Grosshadern, Marchioninistrasse 15, 81377 Munich (Germany); Herzog, P., E-mail: peter.herzog@med.uni-muenchen.d [Institute of Clinical Radiology, University Hospital Munich - Grosshadern, Ludwig Maximilians-Universitaet Muenchen, Klinikum Grosshadern, Marchioninistrasse 15, 81377 Munich (Germany); Johnson, T., E-mail: Thorsten.johnson@med.uni-muenchen.d [Institute of Clinical Radiology, University Hospital Munich - Grosshadern, Ludwig Maximilians-Universitaet Muenchen, Klinikum Grosshadern, Marchioninistrasse 15, 81377 Munich (Germany); Boehm, H., E-mail: holger.boehm@med.uni-muenchen.d [Institute of Clinical Radiology, University Hospital Munich - Grosshadern, Ludwig Maximilians-Universitaet Muenchen, Klinikum Grosshadern, Marchioninistrasse 15, 81377 Munich (Germany); Nikolaou, K., E-mail: konstantin.nikolaou@med.uni-muenchen.d [Institute of Clinical Radiology, University Hospital Munich - Grosshadern, Ludwig Maximilians-Universitaet Muenchen, Klinikum Grosshadern, Marchioninistrasse 15, 81377 Munich (Germany); Reiser, M.F., E-mail: maximilian.reiser@med.uni-muenchen.d [Institute of Clinical Radiology, University Hospital Munich - Grosshadern, Ludwig Maximilians-Universitaet Muenchen, Klinikum Grosshadern, Marchioninistrasse 15, 81377 Munich (Germany); Becker, C.H., E-mail: christoph.becker@med.uni-muenchen.d [Institute of Clinical Radiology, University Hospital Munich - Grosshadern, Ludwig Maximilians-Universitaet Muenchen, Klinikum Grosshadern, Marchioninistrasse 15, 81377 Munich (Germany)

    2010-06-15

    Objective: The radiation exposure of a dual-source-64-channel multi-detector-computed-tomography-scanner (Somatom-Defintion, Siemens, Germany) was assessed in a phantom-study performing coronary-CT-angiography (CTCA) in comparison to patients' data randomly selected from routine scanning. Methods: 240 CT-acquisitions of a computed tomography dose index (CTDI)-phantom (PTW, Freiburg, Germany) were performed using a synthetically generated Electrocardiography (ECG)-signal with variable heart rates (30-180 beats per minute (bpm)). 120 measurements were acquired using continuous tube-output; 120 measurements were performed using ECG-synchronized tube-modulation. The pulsing window was set at minimum duration at 65% of the cardiac cycle between 30 and 75 bpm. From 90-180 bpm the pulsing window was set at 30-70% of the cardiac cycle. Automated pitch adaptation was always used. A comparison between phantom CTDI and two patient groups' CTDI corresponding to the two pulsing groups was performed. Results: Without ECG-tube-modulation CDTI-values were affected by heart-rate-changes resulting in 85.7 mGray (mGy) at 30 and 45 bpm, 65.5 mGy/60 bpm, 54.7 mGy/75 bpm, 46.5 mGy/90 bpm, 34.2 mGy/120 bpm, 27.0 mGy/150 bpm and 22.1 mGy/180 bpm equal to effective doses between 14.5 mSievert (mSv) at 30/45 bpm and 3.6 mSv at 180 bpm. Using ECG-tube-modulation these CTDI-values resulted: 32.6 mGy/30 bpm, 36.6 mGy/45 bpm, 31.4 mGy/60 bpm, 26.8 mGy/75 bpm, 23.7 mGy/90 bpm, 19.4 mGy/120 bpm, 17.2 mGy/150 bpm and 15.6 mGy/180 bpm equal to effective doses between 5.5 mSv at 30 bpm and 2.6 mSv at 180 bpm. Significant CTDI-differences were found between patients with lower/moderate and higher heart rates in comparison to the phantom CTDI-results. Conclusions: Dual source CTCA is particularly dose efficient at high heart rates when automated pitch adaptation, especially in combination with ECG-based tube-modulation is used. However in clinical routine scanning for patients with higher

  11. Niche partitioning of marine group I Crenarchaeota in the euphotic and upper mesopelagic zones of the East China Sea.

    Science.gov (United States)

    Hu, Anyi; Jiao, Nianzhi; Zhang, Rui; Yang, Zao

    2011-11-01

    Marine group I Crenarchaeota (MGI) represents a ubiquitous and numerically predominant microbial population in marine environments. An understanding of the spatial dynamics of MGI and its controlling mechanisms is essential for an understanding of the role of MGI in energy and element cycling in the ocean. In the present study, we investigated the diversity and abundance of MGI in the East China Sea (ECS) by analysis of crenarchaeal 16S rRNA gene, the ammonia monooxygenase gene amoA, and the biotin carboxylase gene accA. Quantitative PCR analyses revealed that these genes were higher in abundance in the mesopelagic than in the euphotic zone. In addition, the crenarchaeal amoA gene was positively correlated with the copy number of the MGI 16S rRNA gene, suggesting that most of the MGI in the ECS are nitrifiers. Furthermore, the ratios of crenarchaeal accA to amoA or to MGI 16S rRNA genes increased from the euphotic to the mesopelagic zone, suggesting that the role of MGI in carbon cycling may change from the epipelagic to the mesopelagic zones. Denaturing gradient gel electrophoretic profiling of the 16S rRNA genes revealed depth partitioning in MGI community structures. Clone libraries of the crenarchaeal amoA and accA genes showed both "shallow" and "deep" groups, and their relative abundances varied in the water column. Ecotype simulation analysis revealed that MGI in the upper ocean could diverge into special ecotypes associated with depth to adapt to the light gradient across the water column. Overall, our results showed niche partitioning of the MGI population and suggested a shift in their ecological functions between the euphotic and mesopelagic zones of the ECS.

  12. Long-Term Musical Group Interaction Has a Positive Influence on Empathy in Children

    Science.gov (United States)

    Rabinowitch, Tal-Chen; Cross, Ian; Burnard, Pamela

    2013-01-01

    Musical group interaction (MGI) is a complex social setting requiring certain cognitive skills that may also elicit shared psychological states. We argue that many MGI-specific features may also be important for emotional empathy, the ability to experience another person's emotional state. We thus hypothesized that long-term repeated…

  13. Long-Term Musical Group Interaction Has a Positive Influence on Empathy in Children

    Science.gov (United States)

    Rabinowitch, Tal-Chen; Cross, Ian; Burnard, Pamela

    2013-01-01

    Musical group interaction (MGI) is a complex social setting requiring certain cognitive skills that may also elicit shared psychological states. We argue that many MGI-specific features may also be important for emotional empathy, the ability to experience another person's emotional state. We thus hypothesized that long-term repeated participation…

  14. Determinación de la velocidad del viento estelar en el sistema planetario HD 209458

    Science.gov (United States)

    Villarreal D'Angelo, C. S.; Schneiter, M.; Costa, A.

    In this work we propose a method to indirectly determine the velocity of the stellar wind, ve , of the G0 V star HD 209458 (M = 1, 148M ) which is known to have a transiting planet HD 209458b (M p = 0, 714MJ ). To estimate the value of the stellar wind, we simulated the problem assum- ing diferent values of ve and m p . For each model (different pairs of ve and m p ) we adjusted the value of m p to obtain the observed 5% of absorption in Ly-a for the whole line width. Then, we calculate the Ly-a absorption for different widths of the line. The best fit model is determined by comparing with the observations. FULL TEXT IN SPANISH

  15. Effects of (60)Co gamma irradiation on behavior and gill histoarchitecture of giant fresh water prawn Macrobrachium rosenbergii (DE MAN).

    Science.gov (United States)

    Stalin, A; Broos, K V; Sadiq Bukhari, A; Syed Mohamed, H E; Singhal, R K; Venu-babu, P

    2013-06-01

    Present study was designed to observe the effects of (60)Co gamma radiation in behavioral and histological changes in the gills of giant fresh water prawn Macrobrachium rosenbergii. The adult prawns were irradiated with four different dose levels (3mGy, 30mGy, 300mGy and 3000mGy) and the control group (without irradiation) was maintained separately. Behavioral changes like hyperactivity, loss of balance, reduced swimming rate, slower rate of food intake and convulsions were observed in higher dose levels of 300mGy and 3000mGy. The histological alterations such as accumulated haemocytes in haemocoelic spaces, abnormal gill tips, lifted lamellar epithelium, swollen and fused lamellae, hyperplasic, necrotic, clavate-globate and complete disorganization of lamellae were observed in (60)Co gamma irradiated prawns. Significantly more considerable histological alterations were observed in the highest dose level of 3000mGy, but no mortality was evidenced. This study serves as biomonitoring tool to assess the radiation pollution in the aquatic environment.

  16. IN VITRO CULTURE OF HOLOPARASITE Rafflesia arnoldii R. Brown

    Directory of Open Access Journals (Sweden)

    Lazarus Agus Sukamto

    2010-07-01

    Full Text Available Potongan kuncup bunga digunakan sebagai eksplan yang ditumbuhkan pada media dasar Murashige and Skoog (MS dengan tambahan 0; 0.1; 0.5; 1 and 5 mg/I 2,4-D atau Picloram dan 2 g/I Phytagel. Eksplan tumbuh menjadi kalus pada media yang ditambahkan 0,1 dan 1 mg/I 2,4-D atau 0,5 dan 1 mg/I Picloram. Kultur kalus tersebut dipelihara pada media MS + 1 mg/I 2,4-D. Kemudian kalus ditumbuhkan pada medium dengan penambahan 1, 3, 5 dan 10 mg/I 2,4-D atau Picloram. Setelah dua bulan 66,67-100% kultur membentuk kalus. Semua kalus berstruktur kompak. Beberapa kalus yang diperlakuan dengan 5-10 mg/I 2,4-D menumbuhkan benang-benang putih pada permukaannya. Perlakuan Picloram menghasilkan kalus yang lebih banyak, tetapi 2,4-D menghasilkan kualitas kalus yang lebih baik. Kalus R. arnoldii tidak membentuk somatik embrio dengan penambahan 0,1 mg/I Zeatin dalam media kultur. Ini adalah laporan yang pertama kali tentang pembentukan kalus dari kultur R. arnoldii secara in vitro.

  17. Trends and Issues in Distance Education: International Perspectives

    OpenAIRE

    2006-01-01

    Trends and Issues in Distance Education: International Perspectives Edited by Yusra Laila Visser, Lya Visser, Michael Simonsın, & Ray Amirault, 2005, United States of America: Information Age Publishing, Inc. pp. 315. ISBN 1-59311-212-2 Reviewed by Dr. Erhan EROGLU Anadolu University Eskisehir, TURKEY In this book, the terms of “distance education” has been discussed from different perspectives. The term “distance education” conjures up in many minds the image of modern, computer-enabled t...

  18. Proof of the WARM whisker conjecture for neuronal connections

    Science.gov (United States)

    Holmes, Mark; Kleptsyn, Victor

    2017-04-01

    This paper is devoted to the study of the so-called WARM reinforcement models that are generalisations of Pólya's urn. We show that in the graph setting, once the exponent α of the reinforcement function is greater than 2, the stable and critical equilibria can be supported only on spanning forests, and once α > 25 , on spanning whisker forests. Thus, we prove the whisker forests conjecture from Hofstad et al. [Ann. Appl. Probab. 26(4), 2494-2539 (2016)].

  19. A Diaz--Metcalf type inequality for positive linear maps and its applications

    CERN Document Server

    Moslehian, M S; Seo, Y

    2011-01-01

    We present a Diaz--Metcalf type operator inequality as a reverse Cauchy-Schwarz inequality and then apply it to get the operator versions of P\\'{o}lya-Szeg\\"{o}'s, Greub-Rheinboldt's, Kantorovich's, Shisha-Mond's, Schweitzer's, Cassels' and Klamkin-McLenaghan's inequalities via a unified approach. We also give some operator Gr\\"uss type inequalities and an operator Ozeki-Izumino-Mori-Seo type inequality. Several applications are concluded as well.

  20. Sensitivity Tests of a Surface-Layer Windflow Model to Effects of Stability and Vegetation.

    Science.gov (United States)

    1985-10-25

    ORGANIZATION [b. OFFICE SYMBOL 7a NAME OF MONITORING ORGANIZATION Air Force Geophysics L.aborator y LYA 6. ADDRESS cis SIdtt..d /11 CIdP 7tb ADDRESSL.1...between 1 " J University 12 reasonably accurate wind and 2 km above speeds and directions while ground level (AGL), incorporating effects of sur- so it is...several reasons why a variational approach is appropriate for this 4modeling application. Ball and Johnson stated that the advection terms of the

  1. Far Infrared Spectroscopy of the Nearby Analogues of High-Redshift Galaxies

    Science.gov (United States)

    Hayes, Matthew

    2014-10-01

    We propose far infrared emission line spectroscopy of a sample of 23 local star-forming galaxies, drawn from the Lyman alpha Reference Sample (LARS), for which we have unrivalled high-resolution imaging and spectroscopy from HST, and 21cm HI observations from VLA+GMRT. Moreover the galaxies are selected as the close analogues of the high-redshift Lyman-break galaxies and Spitzer+Herschel selected galaxies found in extragalactic deep fields. The science goal of LARS is to determine what governs the escape of Lyman alpha (Lya) photons from galaxies, and thereby aid interpretation of high-z observations where Lya is the most used spectral probe. However given its clean selection and multiwavelength nature, LARS can equally well improve our understanding of FIR line observations of high-z galaxies. The target emission lines in this proposal are [CII], [OI], and [OIII] at 158, 63, and 88 micron, respectively. The motivations are that these lines: 1. are of increasing interest at high-z as new sensitive submm/radio interferometers come online 2. are proposed quantitative tracers of star formation rates, but their utility must be proven in appropriately analogous well-studied galaxies 3. when combined with models of photodissociation regions, enable estimates of the density and mass of PDR gas and provide vital constraints on our Lya radiative transfer models of galaxies. 4. provide uniquely robust estimates of nebular extinction and metallicity when combined with our optical IFU data. Astrophysical applications are many, especially when combined with the array of existing data. Specifically they will provide vital constraints on ISM structure, that are required for understanding the emission of the cosmologically vital Lya emission line. Moreover, SFR calibrations will be tested in star forming environments that resemble those of early galaxies and the legacy value of the sample is hard to overstate.

  2. O deslocamento feminino no romance contemporâneo

    Directory of Open Access Journals (Sweden)

    Carlos Magno Gomes

    2012-04-01

    Full Text Available This paper takes up the reflection of gender identity in novels by Lya Luft and Helena Parente Cunha, by means of gender studies. It starts with a feminist conception for the analysis of parody of women's movement as a form of resistance to the patriarchy. This challenge is suggested by the metaphor of the traditional mother's death in these authors’ fiction. Methodologically, the concepts of parody, by Hutcheon, and displacement of gender, by Butler, will be explored.

  3. Dose evaluation in special fluoroscopy procedures: Hysterosalpingography and Dacryocystography; Avaliacao de dose em procedimentos especiais de fluoroscopia: histerossalpingografia e dacriocistografia

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Cintya Carolina Barbosa

    2006-04-15

    The hysterosalpingography (HSG) and dacryocystography (DCG) are among the special fluoroscopy procedures. The HSG is a radiodiagnostic technique used to detect uterine and tubal pathologies and it is fundamental for the investigation of infertility. The DCG is a form of lacrimal system imaging, being important to show the level of obstruction, the presence of dilatation of the lacrimal sac, as well as alterations in nearby structures. At this research, the study of skin entrance dose was evaluated for these two special fluoroscopy procedures, besides the analyses of staff doses whose performs the exams. The exams of 22 HSG patients and 8 DCG patients were evaluated using TL-100 dosimeters attached on patient' skin at anatomical landmarks evolved on each exam. In the case of HSG, the results showed that skin entrance doses varied from 0.5 mGy to 73.4 mGy, with an average value of 22.1 mGy. The estimated uterus dose was 5.5 mGy, and 6.6 mGy was the average dose estimated to the ovaries. The patient' skin entrance dose undergoing to DCG examinations varied from 2.1 mGy to 10.6 mGy, and the average eye's dose was 6.1 mGy. The results of staff dose showed that, on HSG, the average dose on doctor's right hand was 4.3 mGy per examination. This value had to the fact that the physician introduces the contrast manually while all contrast exposures. In relation of DCG, the staff's dose values were nearby background radiation, evidencing that, inside of permitted limits, there is no risk for the physicians at this procedure. (author)

  4. Validation of the mother-generated index in Iran: A specific postnatal quality-of-life instrument

    Directory of Open Access Journals (Sweden)

    Roghayeh Khabiri

    2013-01-01

    Full Text Available Background: The mother-generated index (MGI is one of only a few existing specific questionnaires for assessing the postnatal quality of life (QoL. MGI is a single-form questionnaire that asks postnatal mothers to specify up to eight areas of their lives which have been affected by giving birth to a baby. Using this tool, it is possible to score and rank the QoL of mothers. This study aimed to validate the questionnaire for use in Iran. Methods : Forward translation was used to translate the questionnaire from English to Farsi (Persian. The questionnaire was then administered to a sample of postnatal women attending two teaching hospitals in Tehran, Iran. Face validity and criterion validity were performed to establish the validity for the Iranian version of the MGI. Face validity was assessed by asking women to indicate whether they understood the wording of the questions, how easy the questionnaire was, and so on. Criterion validity was examined using the Short Form 36-item (SF-36 Health Survey. It was hypothesized that the MGI would significantly correlate with the SF-36. Results: In all, 124 women were approached. Of these, 119 women were eligible and 96 women agreed to take part in the study. Face validity was good and all of the women found the MGI straightforward to complete; as criterion validity, the MGI scores and the subscales of the SF-36 were moderately correlated (for all subscales: Pearson r > 0.4; P < 0.001. The mean MGI primary score was 5.38 (SD = 3.05. Women who had comorbidity had significantly lower MGI scores than women without comorbidity (P = 0.04. Correlation between aggregate of comments and primary score was high (r = 0.68, P < 0.01. Conclusions: In general, the Iranian version of the MGI performed well and our data suggest that it is a valid measure to assess health-related QoL among postnatal women.

  5. Preliminary evaluation of exposures of computerized tomography patients in Latin America: IAEA project RLA/9/67; Avaliacao preliminar das exposicoes de pacientes em tomografia computadorizada na America Latina: Projeto IAEA RLA/9/67

    Energy Technology Data Exchange (ETDEWEB)

    Kodlulovich, S.; Silveira, V. [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil); Khoury, H.J. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Departamcnto de Energia Nuclear; and others

    2013-07-01

    The aim of this study was to obtain preliminary values of reference levels in CT . Were sent to each country forms with information of radiological protection and routine CT protocols. The CT dose index and absorbed dose to organs was estimated from the technical data for each equipment . The results showed that the total number of examinations performed 92 % are adult patients and 8 % are children. The most frequent examination of the skull was adult (40 % ) and abdomen for children (42 % ) . About the service , 67 % of the equipment are multicut and 76 % have specific protocols for pediatric patients. The CTDI{sub vol} values for head exams of adults vary between 2 and 352 mGy for pediatric patients under 1 year 1-191 mGy under 7 years old 5-335 mGy. For chest values ranged from 3 to 26 mGy for adults, between 1 and 89 mGy for children under 1 year and between 3-114 mGy for children between 1 and 7 years. Exams of the abdomen/pelvis of adults the range was 3-47 mGy , between 4-90 mGy for children under 1 year and between 2-31 mGy for children between 1 and 7 years. This study showed that although there are pediatric protocols, there is a wide variation in values of CTDl{sub vol} indicating a high potential for dose reduction. This result requires immediate action for optimization and implementation of diagnostic reference values in Latin America.

  6. Metal Abundances in a Damped Lyman-alpha System Along Two Lines of Sight at z=0.93

    CERN Document Server

    López, S; Gregg, M D; Wisotzki, L; Wucknitz, O; Guzman, A

    2005-01-01

    We study metal abundances in the z=0.9313 damped Lya system observed in the two lines-of-sight, A and B, toward the gravitationally-lensed double QSO HE0512-3329. Spatially resolved STIS spectra constrain the neutral-gas column density to be LogN(HI)=20.5 in both Aand B. UVES spectra (spectral resolution FWHM=9.8 km/s) show, in contrast, significant line-of-sight differences in the column densities of MnII and FeII; these are not due to observational systematics. We find that [Mn/H]=-1.44 and [Fe/H]=-1.52 in damped Lya system A, while [Mn/H]=-0.98 and [Fe/H]>-1.32, and possibly as high as [Fe/H] approx. -1 in damped Lya system B. A careful assessment of possible systematic errors leads us to conclude that these transverse differences are significant at a 5 sigma level or greater. Although nucleosynthesis effects may also be at play, we favor differential dust-depletion as the main mechanism producing the observed abundance gradient. The transverse separation is 5 kpc at the redshift of the absorber, which is ...

  7. The Ultraviolet Emission Properties of Five Low-Redshift Active Galactic Nuclei at High Signal to Noise and Spectral Resolution

    CERN Document Server

    Laor, A; Jannuzi, B T; Schneider, D P; Green, R F; Hartig, G F; Laor, Ari; Bahcall, John N.; Jannuzi, Buell T.; Schneider, Donald P.; Green, IAS; Richard F.; Hartig, NOAO; George F.; ScI, ST

    1994-01-01

    We analyze the ultraviolet (UV) emission line and continuum properties of five low-redshift active galactic nuclei (four luminous quasars: PKS~0405$-$123, H1821+643, PG~0953+414, and 3C273, and one bright Seyfert 1 galaxy: Mrk~205). The HST spectra have higher signal-to-noise ratios (typically $\\sim 60$ per resolution element) and spectral resolution ($R = 1300$) than all previously- published UV spectra used to study the emission characteristics of active galactic nuclei. We include in the analysis ground-based optical spectra covering \\hb\\ and the narrow [O~III]~$\\lambda\\lambda$4959,5007 doublet. The following new results are obtained: \\lyb/\\lya=0.03$-$0.12 for the four quasars, which is the first accurate measurement of the long-predicted \\lyb\\ intensity in QSOs. The cores of \\lya\\ and C~IV are symmetric to an accuracy of better than 2.5\\% within about 2000~km~s$^{-1}$ of the line peak. This high degree of symmetry of \\lya\\ argues against models in which the broad line cloud velocity field has a significan...

  8. Searching for candidates of Lyman continuum sources - revisiting the SSA22 field

    CERN Document Server

    Micheva, Genoveva; Inoue, Akio K; Matsuda, Yuichi; Yamada, Toru; Hayashino, Tomoki

    2015-01-01

    We present the largest to date sample of hydrogen Lyman continuum (LyC) emitting galaxies at any redshift, with $18$ LyA Emitters (LAEs) and $7$ Lyman Break Galaxies (LBGs), obtained from the SSA22 field with Subaru/Suprime-Cam. The sample is based on the $136$ LBGs and $159$ LAEs observed in the field, all with spectroscopically confirmed redshifts, and they are selected as galaxies with counterpart in a narrow-band filter image which traces LyC at $z\\geq 3.06$. Many LyC candidates show a spatial offset between the rest-frame non-ionizing ultraviolet (UV) detection and the LyC-emitting substructure or between the LyA emission and LyC. Statistically it is highly unlikely that all candidates in our sample are contaminants, and there should be $\\sim9$ and $\\sim2$ viable LyC candidates among the LAEs and LBGs. There is some evidence for a positive LyC/LyA correlation, suggesting that both LyC and LyA escape via a similar mechanism. "Standard" SED models cannot explain the observed LyC LAEs colors, instead requir...

  9. Extended Lyman-alpha emission from cold accretion streams

    CERN Document Server

    Rosdahl, J

    2011-01-01

    {Abridged} We investigate the observability of cold accretion streams at redshift 3 via Lyman-alpha radiation and the feasibility of cold accretion as the main driver behind giant Lya blobs (LABs). We run cosmological zoom simulations focusing on 3 halos spanning two orders of magnitude in mass, from 10^11 to 10^13 solar masses. We use a version of the AMR code Ramses that includes radiative transfer of UV photons, and we employ a refinement strategy that allows us to resolve accretion streams in their natural environment to an unprecedented level. For the first time, we self-consistently model self-shielding in the cold streams from the cosmological UV background, which enables us to accurately predict their temperatures, ionization states and Lya luminosities. We find the efficiency of gravitational heating in cold streams in a ~10^11 solar mass halo is around 10-20% throughout most of the halo but reaching much higher values close to the center. As a result most of the Lya luminosity comes from the circumg...

  10. LBT/MODS1 spectroscopic confirmation of two faint sources at z=6.4 magnified by the CLASH / Frontier Fields cluster MACSJ0717.5+3745: towards the characterization of star-forming galaxies at the epoch of reionization

    CERN Document Server

    Vanzella, E; Zitrin, A; Coe, D; Bradley, L; Postman, M; Grazian, A; Castellano, M; Pentericci, L; Giavalisco, M; Rosati, P; Nonino, M; Smit, R; Balestra, I; Bouwens, R; Cristiani, S; Giallongo, E; Zheng, W; Infante, L; Cusano, F; Speziali, R

    2013-01-01

    We report the LBT/MODS1 spectroscopic confirmation of two images of faint Lyman alpha emitters at z=6.4 behind the Frontier Fields galaxy cluster MACSJ0717.5+3745. A wide range of lens models suggests that the two images are highly magnified, with a strong lower limit of mu>5. These are the faintest z>6 candidates spectroscopically confirmed to date. These may be also multiple images of the same z=6.4 source as supported by their similar intrinsic properties, but the lens models are inconclusive regarding this interpretation. To be cautious, we derive the physical properties of each image individually. Thanks to the high magnification, the observed near-infrared (restframe ultraviolet) part of the spectral energy distributions and Lya lines are well detected with S/N(m_1500)>~10 and S/N(Lya)~10-15. Adopting mu > 5, the absolute magnitudes, M_1500, and Lya fluxes, are fainter than -18.7 and 2.8x10^-18 erg/s/cm2, respectively. We find a very steep ultraviolet spectral slope beta=-3.0+/-0.5 (F_lambda=lambda^beta...

  11. The Properties of Lyman Alpha Nebulae: Gas Kinematics from Non-resonant Lines

    CERN Document Server

    Yang, Yujin; Jahnke, Knud; Davé, Romeel

    2014-01-01

    [Abridged] With VLT/X-shooter, we obtain optical and NIR spectra of six Ly-alpha blobs at z~2.3. Using three measures --- the velocity offset between the Lya line and the non-resonant [OIII] or H-alpha line (Dv_Lya), the offset of stacked interstellar metal absorption lines, and the spectrally-resolved [OIII] line profile --- we study the kinematics of gas along the line of sight to galaxies within each blob center. These three indicators generally agree in velocity and direction, and are consistent with a simple picture in which the gas is stationary or slowly outflowing at a few hundred km/s from the embedded galaxies. The absence of stronger outflows is not a projection effect: the covering fraction for our sample is limited to <1/8 (13%). The outflow velocities exclude models in which star formation or AGN produce "super" or "hyper" winds of up to ~1000km/s. The Dv_Lya offsets here are smaller than typical of LBGs, but similar to those of compact LAEs. The latter suggests that outflow speed cannot be a...

  12. Warm Dark Matter as a solution to the small scale crisis: new constraints from high redshift Lyman-alpha forest data

    CERN Document Server

    Viel, M; Bolton, J S; Haehnelt, M G

    2013-01-01

    We present updated constraints on the free-streaming of warm dark matter (WDM) particles derived from an analysis of the Lya flux power spectrum measured from high-resolution spectra of 25 z > 4 quasars obtained with the Keck High Resolution Echelle Spectrometer (HIRES) and the Magellan Inamori Kyocera Echelle (MIKE) spectrograph. We utilize a new suite of high-resolution hydrodynamical simulations that explore WDM masses of 1, 2 and 4 keV (assuming the WDM consists of thermal relics), along with different physically motivated thermal histories. We carefully address different sources of systematic error that may affect our final results and perform an analysis of the Lya flux power with conservative error estimates. By using a method that samples the multi-dimensional astrophysical and cosmological parameter space, we obtain a lower limit mwdm > 3.3 keV (2sigma) for warm dark matter particles in the form of early decoupled thermal relics. Adding the Sloan Digital Sky Survey (SDSS) Lya flux power spectrum does...

  13. The Lyman-alpha Forest as a Cosmological Tool

    CERN Document Server

    Weinberg, D H; Katz, N; Kollmeier, J A; Weinberg, David H.; Dav'e, Romeel; Katz, Neal; Kollmeier, Juna A.

    2003-01-01

    We review recent developments in the theory of the Lyman-alpha forest and their implications for the role of the forest as a test of cosmological models. Simulations predict a relatively tight correlation between the local Lya optical depth and the local gas or dark matter density. Statistical properties of the transmitted flux can constrain the amplitude and shape of the matter power spectrum at high redshift, test the assumption of Gaussian initial conditions, and probe the evolution of dark energy by measuring the Hubble parameter H(z). Simulations predict increased Lya absorption in the vicinity of galaxies, but observations show a Lya deficit within Delta_r ~ 0.5 Mpc/h (comoving). We investigate idealized models of "winds" and find that they must eliminate neutral hydrogen out to comoving radii ~1.5 Mpc/h to marginally explain the data. Winds of this magnitude suppress the flux power spectrum by \\~0.1 dex but have little effect on the distribution function or threshold crossing frequency. In light of the...

  14. MUSE integral-field spectroscopy towards the Frontier Fields cluster Abell S1063: II. Properties of low luminosity Lyman alpha emitters at z>3

    CERN Document Server

    Karman, W; Caminha, G B; Gronke, M; Grillo, C; Balestra, I; Rosati, P; Vanzella, E; Coe, D; Dijkstra, M; Koekemoer, A M; Mercurio, A; Nonino, M

    2016-01-01

    In spite of their conjectured importance for the Epoch of Reionization, the properties of low-mass galaxies are currently still under large debate. In this article, we study the stellar and gaseous properties of faint, low-mass galaxies at z>3. We observed the Frontier Fields cluster Abell S1063 with MUSE over a 2 arcmin^2 field, and combined integral-field spectroscopy with gravitational lensing to perform a blind search for intrinsically faint Lya emitters (LAEs). We found in total 14 lensed LAEs and increased the number of spectroscopically-confirmed multiple-image families from 6 to 17, and updated our gravitational-lensing model accordingly. The lensing-corrected Lya luminosities are with L(Lya) =3 are reported. We performed SED modelling to broadband photometry from the {\\em U}-band through the infrared to determine the stellar properties of these LAEs. The stellar masses are very low (10^{6-8} Msun), and are accompanied by very young ages of 1-100 Myr. The very high specific star formation rates (~100/...

  15. Science Data Management for WSO-UV

    Science.gov (United States)

    Gomez De Castro, Ana; Sachkov, Mikhail; Marcos-Arenal, Pablo; Belén Perea Abarca, G.; Malkov, Oleg

    2016-07-01

    WSO-UV is a 170 primary space telescope that will work in the ultraviolet range (115-315 nm) of the spectrum providing instrumentation for spectroscopy and imaging. WSO-UV is a cornerstone project of the astronomical program of the Russian Space Agency with launch date 2021. Spain and Mexico participate in the project. Scientific observation with WSO-UV will be open to the world wide scientific community after the 1st year of mission. WSO-UV will handle three scientific programs: core, national and open. The core program will be run during the first two years of the mission and will provide unique results that will affect all branches of astrophysics. WSO-UV will be equipped with a camera for very deep imaging in the Hydrogen Lyman-alpha (Lya) line and will be orbiting in a High Earth Orbit (geosynchronous). As a result, it will provide the deepest images ever obtained in this fundamental tracer (Lya is the strongest spectral line in the Universe). In this talk, we describe the strategy for the Lya survey and the foreseen output products and data distribution policy.

  16. Continuum subtracting Lyman-alpha images: Low redshift studies using the Solar Blind Channel of HST/ACS

    CERN Document Server

    Hayes, Matthew; Mas-Hesse, J Miguel; Kunth, Daniel

    2008-01-01

    (Abridged) We are undertaking an imaging study of local star-forming galaxies in the Lyman-alpha (Lya) emission line using the Solar Blind Channel (SBC) of the ACS onboard HST. Observations have been obtained in Lya and H-alpha and six line-free continuum filters between ~1500 AA and the I-band. In a previous article Hayes et al. (2005) we demonstrated that the production of Lya line-only images (i.e. continuum subtraction) in the SBC-only data-set is non-trivial and that supporting data is a requirement. We here develop various methods of continuum subtraction and assess their relative performance for given input spectral energy distributions (SED). We show that simple assumptions about the behavior of the UV continuum consistently lead to results that are significantly in error, and determine that a spectral fitting approach is essential. Furthermore, fitting of a single component stellar or stellar+nebular spectrum is not always sufficient for realistic template SEDs and, in order to successfully recover t...

  17. Probing the Circumgalactic Medium at High-Redshift Using Composite BOSS Spectra of Strong Lyman-alpha Forest Absorbers

    CERN Document Server

    Pieri, Matthew M; Frank, Stephan; Crighton, Neil; Weinberg, David H; Lee, Khee-Gan; Noterdaeme, Pasquier; Bailey, Stephen J; Busca, Nicolas; Ge, Jian; Kirkby, David; Lundgren, Britt; Mathur, Smita; Paris, Isabelle; Palanque-Delabrouille, Nathalie; Petitjean, Patrick; Rich, James; Ross, Nicholas P; Schneider, Donald P; York, Donald G

    2013-01-01

    We present composite spectra constructed from a sample of 242,150 Lyman-alpha (Lya) forest absorbers at redshifts 2.4Lya absorption is associated with decreasing purity of circumgalactic selection once BOSS noise is included. Our weaker two Lya absorption samples are dominated by the intergalactic medium. We present composite spectra of these samples and a...

  18. Broad Ly alpha Emission from Three Nearby BL Lacertae Objects

    CERN Document Server

    Stocke, John T; Perlman, Eric S

    2011-01-01

    We present far-UV HST/COS spectra of four nearby BL Lac Objects. BL Lac spectra are dominated by a smooth, power-law continuum which arises in a relativistic jet. However, the spectra are not necessarily featureless; weak, broad- and/or narrow-line emission is sometimes seen in high-quality optical spectra. We present detections of Lya emission in HST/COS spectra of Mrk421 (z=0.030) and PKS2005-489 (z=0.071) as well as an archival HST/GHRS observation of Mrk501 (z=0.0337). Archival HST/STIS observations of PKS2155-304 (z=0.116) show no Lya emission to a very low upper limit. Using the assumption that the broad-line region (BLR) clouds are asymmetrically placed around the AGN, we use these measured Lya emission features to constrain either the relativistic Gamma values for the ionizing continuum produced by the jet (in the ionization-bounded case) or the mass of warm gas (in the density-bounded case). While realistic Gamma values can be obtained for all four cases, the values for Mrk421 and PKS2155-304 are hig...

  19. The Local Lyman-$\\alpha$ Forest; 1, Distribution of HI Absorbers, Doppler Widths, and Baryon Content

    CERN Document Server

    Penton, S V; Stocke, J T; Penton, Steven V.; Stocke, John T.

    1999-01-01

    In Paper I of this series (astro-ph/9911117) we described observations of 15 extragalactic targets taken with the Hubble Space Telescope GHRS/G160M grating for studies of the low-z Lya forest. We reported the detection of 110 Lya absorbers at significance level >3 sigma in the redshift range z=0.002-0.069, over a total pathlength of 116,000 km/s. In this second paper, we evaluate the physical properties of these Lya absorbers and compare them to their high-z counterparts. The distribution of Doppler parameters is similar to that at high redshift, with mean b = 35.0 +- 16.6 km/s. The true Doppler parameter may be somewhat lower, owing to component blends and non-thermal velocities. The distribution of equivalent widths exhibits a significant break at W~133mA, with an increasing number of weak absorbers (10mA-100mA). Adopting a curve of growth with b = 25 +- 5km/s and applying a sensitivity correction as a function of equivalent width and wavelength, we derive the distribution in column density, Nh^{-1.80+-0.05...

  20. Lyman alpha emitting galaxies at 0.2 < z < 0.35 from GALEX spectroscopy

    CERN Document Server

    Deharveng, Jean-Michel; Barlow, Tom A; Peroux, Celine; Milliard, Bruno; Friedman, Peter G; Martin, D Christopher; Morrissey, Patrick; Schiminovich, David; Forster, Karl; Seibert, Mark; Wyder, Ted K; Bianchi, Luciana; Donas, Jose; Heckman, Timothy M; Lee, Young-Wook; Madore, Barry F; Neff, Susan G; Rich, R Michael; Szalay, A S; Welsh, Barry Y; Yi, Sukyoung K

    2008-01-01

    The GALEX (Galaxy Evolution Explorer) spectroscopic survey mode, with a resolution of about 8 A in the FUV (1350 - 1750 A) and about 20 A in the NUV (1950 - 2750 A) is used for a systematic search of Ly-a emitting galaxies at low redshift. This aims at filling a gap between high-redshift surveys and a small set of objects studied in detail in the nearby universe. A blind search of 7018 spectra extracted in 5 deep exposures (5.65 sq.deg) has resulted in 96 Ly-a emitting galaxy candidates in the FUV domain, after accounting for broad-line AGNs. The Ly-a EWs (equivalent width) are consistent with stellar population model predictions and show no trends as a function of UV color or UV luminosity, except a possible decrease in the most luminous that may be due to small-number statistics. Their distribution in EW is similar to that at z about 3 but their fraction among star-forming galaxies is smaller. Avoiding uncertain candidates, a sub-sample of 66 objects in the range 0.2 < z < 0.35 has been used to build ...

  1. Imaging dose evaluations on image guided radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Sun Boong; KIm, Ki Hwan; Kim, Il Hwan; Kim, Woong; Im, Hyeong Seo; Han, Su Chul; Kang, Jin Mook; Kim, Jin Ho [Dept. of Radiotherapy, Korea Institute of Radiological and Medical Sciences, Seoul(Korea, Republic of)

    2015-06-15

    Evaluating absorbed dose related to 2D and 3D imaging confirmation devices. According to the radiographic projection conditions, absorbed doses are measured that 3 glass dosimeters attached to the centers of 0°, 90°, 180°and 270° in the head, thorax and abdomen each with Rando phantom are used in field size 26.6×20, 15×15. In the same way, absorbed doses are measured for width 16 cm and 10 cm of CBCT each. OBI(version 1.5) system and calibrated glass dosimeters are used for the measurement. AP projection for 2D imaging check, In 0° absorbed doses measured in the head were 1.44±0.26 mGy with the field size 26.6×20, 1.17±0.02 mGy with the field size 15×15. With the same method, absorbed doses in the thorax were 3.08±0.86 mGy to 0.57±0.02 mGy by reducing field size. In the abdomen, absorbed dose were reduced 8.19±0.54 mGy to 4.19±0.09 mGy. Finally according to the field size, absorbed doses has decreased by average 5-12%. With Lateral projection, absorbed doses showed average 5-8% decrease. CBCT for 3D imaging check, CBDI in the head were 4.39±0.11 mGy to 3.99±0.13 mGy by reducing the width 16 cm to 10 cm. In the same way in thorax the absorbed dose were reduced 34.88±0.93(10.48±0.09) mGy to 31.01±0.3(9.30±0.09) mGy and 35.99±1.86 mGy to 32.27±1.35 mGy in the abdomen. With variation of width 16 cm and 10 cm, they showed 8-11% decrease. By means of reducing 2D field size, absorbed dose were decreased average 5-12% in 3D width size 8-11%. So that it is necessary for radiation therapists to recognize systematical management for absorbed dose for Imaging confirmation. and also for frequent CBCT, it is considered whether or not prescribed dose for RT refer to imaging dose.

  2. Research Update: The materials genome initiative: Data sharing and the impact of collaborative ab initio databases

    Science.gov (United States)

    Jain, Anubhav; Persson, Kristin A.; Ceder, Gerbrand

    2016-05-01

    Materials innovations enable new technological capabilities and drive major societal advancements but have historically required long and costly development cycles. The Materials Genome Initiative (MGI) aims to greatly reduce this time and cost. In this paper, we focus on data reuse in the MGI and, in particular, discuss the impact of three different computational databases based on density functional theory methods to the research community. We also discuss and provide recommendations on technical aspects of data reuse, outline remaining fundamental challenges, and present an outlook on the future of MGI's vision of data sharing.

  3. Evaluation of skin dose in tomographic radiographs of temporomandibular joint; Avaliacao da dose pele em radiografias tomograficas da articulacao tempromandibular

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, S.B.; Chaves, F.C.; Rocha, F.E.F.C. [Pernambuco Univ., Recife, PE (Brazil). Dept. de Clinica e Odontologia Preventiva; Khoury, H.J. [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear]. E-mail: khoury@elogica.com.br

    2001-07-01

    The aim of this study was to evaluate the skin entrance dose, in patients with temporomandibular joint (TMJ) dysfunctions submitted to computerized tomography. For this purpose, in a private medical establishment, in the city of Recife-Pe/Br, 40 patients were evaluated, in according to radiation doses received in eyes, thyroid and TMJ regions. The value found for eye region range from 0.004 to 0.125 mGy, for thyroid range from 0.002 to 0.113 mGy and for TMJ range from 0.112 to 0.541 mGy.

  4. Electron beam irradiation effects on poly(ethylene terephthalate)

    Energy Technology Data Exchange (ETDEWEB)

    Burillo, G. [Departamento de Quimica de Radiaciones y Radioquimica, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Mexico, DF 04510 (Mexico)], E-mail: burillo@nucleares.unam.mx; Tenorio, L.; Bucio, E. [Departamento de Quimica de Radiaciones y Radioquimica, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Mexico, DF 04510 (Mexico); Adem, E. [Departamento de Fisica Experimental, Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Mexico, DF 04510 (Mexico); Lopez, G.P. [Department of Chemical and Nuclear Engineering, Center for Biomedical Engineering, University of New Mexico, Albuquerque, NM 87131 (United States)

    2007-11-15

    Changes in poly(ethylene terephthalate) subjected to electron beam irradiation at doses up to 15 MGy and dose rate of 1.65 MGy/h, were investigated by differential scanning calorimetry, molecular weight measurement, X-ray photoelectron spectroscopy, and scanning electron microscopy. Irradiated samples showed a decrease of molecular weight with a minimum at 5 MGy, which is attributed to chain scission of the macromolecules and then an increase at further doses due to branching and some degradation effect. Irradiation in air is not an important factor because the high dose rate of irradiation inhibits oxygen diffusion in the samples.

  5. Positron annihilation and thermally stimulated current of electron beam irradiated polyetheretherketone

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, Shigetaka; Shinyama, Katsuyoshi; Baba, Makoto [Hachinohe Inst. of Tech., Hachinohe, Aomori (Japan); Suzuki, Takenori

    1997-03-01

    Positron lifetime measurements were applied to electron beam irradiated poly(ether-ether-ketone). The lifetime, {tau}{sub 3}, of the ortho-positronium of unirradiated and 5 MGy irradiated specimen became rapidly longer above about 150degC. {tau}{sub 3} of 50 MGy and 100 MGy irradiated specimen was shorter than that of unirradiated one. Thermally stimulated current (TSC) decreased with increasing the dose before voltage application. In the case of voltage application, a TSC peak appeared and the peak value decreased with increased the dose. The correlation between the results of positron annihilation and TSC was investigated. (author)

  6. Coronary cineangiography and ionizing radiation exposure to patients: analysis of primary and secondary beam; Cineangiografia coronaria y radiacion ionizante a pacientes. Analisis en haz primario y secundario

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, Alfredo; Leyton, Fernando; Silva, Ana Maria; Farias, Eric [Universidad de Chile, Santiago (Chile). Hospital Clinico; Gamarra, Jorge; Oyarzun, Carlos [Comision Chilena de Energia Nuclear (CCHEN), Santiago (Chile)

    2001-07-01

    The purpose of this work was to determine the level of exposure dose to patients during coronariographies in different areas of body. This study has presented the medical surveillance of 18 cases and the radiation monitoring of these patients by TLD in thyroid and pelvis (secondary beam) and, in the right and left scapular region (primary beam) for each one of these procedures. The ionizing radiation received was 215 {+-} 200 mGy in left scapular region (range 1-710) and 255{+-}213 mGy in the right scapular region (range 22-635) p=NS. In the pelvic region the ionizing radiation was 0,22{+-}0,06 mGy and in the thyroid region was 3,62{+-}2,44 mGy.

  7. ESR measurements of background doses in teeth of Japanese residents

    Energy Technology Data Exchange (ETDEWEB)

    Toyoda, S., E-mail: toyoda@dap.ous.ac.jp [Department of Applied Physics, Okayama University of Science, Okayama (Japan); Kondo, A. [Department of Applied Physics, Okayama University of Science, Okayama (Japan); Zumadilov, K.; Hoshi, M. [Research Institute of Radiation Biology and Medicine, Hiroshima University, Hiroshima (Japan); Miyazawa, C. [Deparment of Dentistry, Ohu University, Fukushima (Japan); Ivannikov, A. [Medical Radiological Research Center, Obninsk (Russian Federation)

    2011-09-15

    The background doses for the teeth of Japanese residents were obtained by electron spin resonance (ESR) method. The doses obtained from 77 of 92 samples are less than 100 mGy while the doses of the other samples are high up to 250 mGy. The doses for buccal part of the teeth are higher than lingual part possibly due to contributions from dental X ray examination. A positive correlation was found between the ages of the donors and the obtained doses. The averaged annual ESR dose was calculated to be 0.87 mGy/y. These doses have to be considered in actual retrospective dosimetry studies for possible radiation accidents. The statistically significant critical level for Japanese residents would be about 200 mGy for individual doses and about 100 mGy for averaged group doses for {alpha} = 5% for those with ages older than 50.

  8. CT exposure from pediatric M.D.C.T.: results from the 2007-2008 S.F.I.P.P./I.S.R.N. survey; Niveaux d'exposition en tomodensitometrie multicoupes pediatrique: resultats de l'enquete dosimetrique SFIPP/IRSN 2007-2008

    Energy Technology Data Exchange (ETDEWEB)

    Brisse, H.J. [Institut Curie, Dept. d' Imagerie, 75 - Paris (France); Aubert, B. [Institut de Radioprotection et de Surete Nucleaire (IRSN), Unite d' Expertise en Radioprotection Medicale, 92 - Clamart (France)

    2009-02-15

    Purpose. To evaluate current exposure levels from pediatric MDCT examinations in order to issue recommendations for the routine clinical practice that may be used for establishing future diagnostic reference levels (DRL). Materials and methods. A survey was conducted at hospital sites affiliated with the SFIPP (Societe Francophone d'Imagerie Pediatrique et Prenatale). Tube potential and volume computed tomography dose index (CTDI) vol. values were obtained for three age groups (1, 5 and 10 years) for typical scanning indications of eight anatomical regions. Results. Twenty of 29 sites provided us with a copy of their protocols. All ages groups combined, 97% of protocols used a tension level {<=} 120 kVp. For age groups 1, 5 and 10 years respectively, the 75. percentiles of dose distributions were: 31, 39.5 and 49.5 mGy for the 'head' protocol; 24, 22 and 24 mGy for 'head and neck'; 11, 11, and 11 mGy for 'paranasal sinuses'; 46, 71 and 87 mGy for 'petrous bone'; 3, 3.5 and 5.5 mGy for 'chest'; 2, 3 and 4 mGy for 'low dose lung'; 4, 4.5 and 7 mGy for 'abdomen-pelvis'; 7,11 and 12 mGy for 'bone'. The inter-center discrepancy for doses were still high. Conclusion. This study provided an evaluation of current practices in reference centers for pediatric imaging and allowed readjustment of MDCT dose recommendations. It could help in the development of DRLS for pediatric MDCT. (author)

  9. Emergency CT head and neck imaging: effects of swimmer's position on dose and image quality

    Energy Technology Data Exchange (ETDEWEB)

    Mueck, Fabian G.; Roesch, Sebastian; Geyer, Lucas; Scherr, Michael; Seidenbusch, Michael; Stahl, Robert; Deak, Zsuzsanna; Wirth, Stefan [LMU Klinikum Universitaet Muenchen (Germany). Inst. fuer Klinische Radiologie

    2014-05-15

    To compare the effects of different arm positions on dose exposure and image quality (IQ) in cervical spine CT after trauma in different patient groups. Patients in standard (STD = 126) and in swimmer's position (SWIM = 254) were included. Body mass index (BMI subgroup 1 = underweight to subgroup 4 = obese), anterior-posterior diameter (AP), left-right diameter (LR), area of an ellipse (AoE) and angle between the humeral heads (optimal STD < 3 , optimal SWIM > 10 ) were used as grouping criteria. Computed tomography dose index (CTDI) was documented. Two radiologists rated the IQ at three levels (CV1/2, CV4/5, CV7/T1) using a semi-quantitative scale (0 = not diagnostic, 1 = diagnostic with limitations, 2 = diagnostic without limitations). The Mann-Whitney U test correlations of grouping criteria with dose effects and intra-class correlation (ICC) were calculated. ICC was 0.87. BMI grouping showed the strongest correlation with dose effects: CTDI of optimal STD versus optimal SWIM positioning was 3.17 mGy versus 2.46 mGy (subgroup 1), 5.47 mGy versus 3.97 mGy (subgroup 2), 7.35 mGy versus 5.96 mGy (subgroup 3) and 8.71 mGy versus 8.18 mGy (subgroup 4). Mean IQ at CV7/T1 was 1.65 versus 1.23 (subgroup 1), 1.27 versus 1.46 (subgroup 2), 1.06 versus 1.46 (subgroup 3), 0.79 versus 1.5 (subgroup 4). Patients with a BMI > 20 kg/m{sup 2} benefited from both potential dose reduction and improved image quality at the critical cervicothoracic junction when swimmer's position was used. (orig.)

  10. Bridging the Gap: Linking Simulation and Testing

    Energy Technology Data Exchange (ETDEWEB)

    Krajewski, Paul E.; Carsley, John; Stoudt, Mark R.; Hovanski, Yuri

    2012-09-01

    The Materials Genome Initiative (MGI) which is a key enabler for the Advanced Manufacturing Partnership, announced in 2011 by U.S. President Barack Obama, was established to accelerate the development and deployment of advanced materials. The MGI is driven by the need to "bridge the gap" between (I) experimental results and computational analysis to enable the rapid development and validation of new mateirals, and (II) the processes required to convert these materials into useable goods.

  11. Comparison of radiation absorbed dose in target organs in maxillofacial imaging with panoramic, conventional linear tomography, cone beam computed tomography and computed tomography

    Directory of Open Access Journals (Sweden)

    Panjnoush M.

    2009-12-01

    Full Text Available "nBackground and Aim: The objective of this study was to measure and compare the tissue absorbed dose in thyroid gland, salivary glands, eye and skin in maxillofacial imaging with panoramic, conventional linear tomography, cone beam computed tomography (CBCT and computed tomography (CT."nMaterials and Methods: Thermoluminescent dosimeters (TLD were implanted in 14 sites of RANDO phantom to measure average tissue absorbed dose in thyroid gland, parotid glands, submandibular glands, sublingual gland, lenses and buccal skin. The Promax (PLANMECA, Helsinki, Finland unit was selected for Panoramic, conventional linear tomography and cone beam computed tomography examinations and spiral Hispeed/Fxi (General Electric,USA was selected for CT examination. The average tissue absorbed doses were used for the calculation of the equivalent and effective doses in each organ."nResults: The average absorbed dose for Panoramic ranged from 0.038 mGY (Buccal skin to 0.308 mGY (submandibular gland, linear tomography ranged from 0.048 mGY (Lens to 0.510 mGY (submandibular gland,CBCT ranged from 0.322 mGY (thyroid glad to 1.144 mGY (Parotid gland and in CT ranged from 2.495 mGY (sublingual gland to 3.424 mGY (submandibular gland. Total effective dose in CBCT is 5 times greater than Panoramic and 4 times greater than linear tomography, and in CT, 30 and 22 times greater than Panoramic and linear tomography, respectively. Total effective dose in CT is 6 times greater than CBCT."nConclusion: For obtaining 3-dimensional (3D information in maxillofacial region, CBCT delivers the lower dose than CT, and should be preferred over a medical CT imaging. Furthermore, during maxillofacial imaging, salivary glands receive the highest dose of radiation.

  12. Atrazine is primarily responsible for the toxicity of long-term exposure to a combination of atrazine and inorganic arsenic in the nigrostriatal system of the albino rat.

    Science.gov (United States)

    Bardullas, Ulises; Giordano, Magda; Rodríguez, Verónica Mireya

    2013-01-01

    Chronic and simultaneous exposure to a variety of chemicals present in the environment is an unavoidable fact. However, given the complexity of studying chemical mixtures, most toxicological studies have focused on the effects of short-term exposure to single substances. The aim of this study was to evaluate the effects on the nigrostriatal system of the chronic, simultaneous exposure to two widely distributed substances that have been identified as potential dopaminergic system toxicants, inorganic arsenic (iAs) and atrazine (ATR). Six groups of rats were treated daily for one year with atrazine (10mg ATR/kg), inorganic arsenic (0.5 or 50mgiAs/L of drinking water), or a combination of ATR+0.5mgiAs/L or ATR+50mgiAs/L. The 50mgiAs/L group showed locomotor hypoactivity, while all treatments decreased motor coordination in contrast no effects of treatment were found on the place and response learning tasks. Regarding markers for liver and muscle damage, there were no differences between groups in creatine kinase (CK) or aspartate transaminase (AST) activities, while decreases in lactate dehydrogenase (LDH) levels were found in some exposed groups. The striatal DA content was significantly reduced in ATR, 0.5mgiAs/L, ATR+0.5mgiAs/L, and ATR+50mgiAs/L groups, in comparison to the control group. The number of mesencephalic tyrosine hydroxylase positive cells decreased in the ATR and ATR+0.5mgiAs/L groups compared to the control. In contrast, immunoreactivity to cytochrome oxidase was reduced compared to the control in all treated groups, except for the group treated with 0.5iAsmg alone. Our results indicate that ATR has deleterious effects on dopaminergic neurons and that the combination of ATR and iAs does not exacerbate these effects.

  13. A novel dendrimer based on poly (L-glutamic acid) derivatives as an efficient and biocompatible gene delivery vector

    Science.gov (United States)

    Zeng, Xin; Pan, Shirong; Li, Jie; Wang, Chi; Wen, Yuting; Wu, Hongmei; Wang, Cuifeng; Wu, Chuanbin; Feng, Min

    2011-09-01

    Non-viral gene delivery systems based on cationic polymers have faced limitations related to their relative low gene transfer efficiency, cytotoxicity and system instability in vivo. In this paper, a flexible and pompon-like dendrimer composed of poly (amidoamine) (PAMAM) G4.0 as the inner core and poly (L-glutamic acid) grafted low-molecular-weight polyethylenimine (PLGE) as the surrounding multiple arms was synthesized (MGI dendrimer). The novel MGI dendrimer was designed to combine the merits of size-controlled PAMAM G4.0 and the low toxicity and flexible chains of PLGE. In phosphate-buffered saline dispersions the well-defined DNA/MGI complex above a N/P ratio of 30 showed good stability with particle sizes of approximately 200 nm and a comparatively low polydispersity index. However, the particle size of the DNA/25 kDa polyethylenimine (DNA/PEI 25K) complex was larger than 700 nm under the same salt conditions. The shielding of the compact amino groups at the periphery of flexible PAMAM and biocompatible PLGE chains in MGI resulted in a dramatic decrease of the cytotoxicity compared to native PAMAM G4.0 dendrimer. The in vitro transfection efficiency of DNA/MGI dendrimer complex was higher than that of PAMAM G4.0 dendrimer. Importantly, in serum-containing medium, DNA/MGI complexes at their optimal N/P ratio maintained the same high levels of transfection efficiency as in serum-free medium, while the transfection efficiency of native PAMAM G4.0, PEI 25K and Lipofectamine 2000 were sharply decreased. In vivo gene delivery of pVEGF165/MGI complex into balloon-injured rabbit carotid arteries resulted in significant inhibition of restenosis by increasing VEGF165 expression in local vessels. Therefore, the pompon-like MGI dendrimer may be a promising vector candidate for efficient gene delivery in vivo.

  14. Evaluation of average glandular dose in mammography services in 10 cities of Colombia; Avaliacao de dose glandular media em servicos de mamografia de 10 cidades de Colombia

    Energy Technology Data Exchange (ETDEWEB)

    Alejo-Martinez, H.; Salazar-Hurtado, E.; Puerto-Jimenez, D. [Grupo de Prevencion Temprana Del Cancer, Instituto Nacional de Cancerologia, Bogota D.C. (Colombia)

    2016-07-01

    The objective of this study was to conduct an assessment of dose in 60 mammography services that have screening programs for breast cancer in 10 cities of Colombia. The third quartile of the average glandular dose was 2,29 mGy, range between 1,0 and 5,6 mGy, for the phantom equivalent to a standard breast. This study included mammography units with conventional and digital technology. (author)

  15. Ultra-Fast All-Optical Self-Aware Protection Switching Based on a Bistable Laser Diode

    DEFF Research Database (Denmark)

    An, Yi; Vukovic, Dragana; Lorences Riesgo, Abel;

    2014-01-01

    We propose a novel concept of all-optical protection switching with link failure automatic awareness based on AOWFF. The scheme is experimentally demonstrated using a single MG-Y laser diode with a record switching time ~200 ps.......We propose a novel concept of all-optical protection switching with link failure automatic awareness based on AOWFF. The scheme is experimentally demonstrated using a single MG-Y laser diode with a record switching time ~200 ps....

  16. Effects of Chronic Low-Dose Radiation on Human Neural Progenitor Cells

    Science.gov (United States)

    Katsura, Mari; Cyou-Nakamine, Hiromasa; Zen, Qin; Zen, Yang; Nansai, Hiroko; Amagasa, Shota; Kanki, Yasuharu; Inoue, Tsuyoshi; Kaneki, Kiyomi; Taguchi, Akashi; Kobayashi, Mika; Kaji, Toshiyuki; Kodama, Tatsuhiko; Miyagawa, Kiyoshi; Wada, Youichiro; Akimitsu, Nobuyoshi; Sone, Hideko

    2016-01-01

    The effects of chronic low-dose radiation on human health have not been well established. Recent studies have revealed that neural progenitor cells are present not only in the fetal brain but also in the adult brain. Since immature cells are generally more radiosensitive, here we investigated the effects of chronic low-dose radiation on cultured human neural progenitor cells (hNPCs) derived from embryonic stem cells. Radiation at low doses of 31, 124 and 496 mGy per 72 h was administered to hNPCs. The effects were estimated by gene expression profiling with microarray analysis as well as morphological analysis. Gene expression was dose-dependently changed by radiation. By thirty-one mGy of radiation, inflammatory pathways involving interferon signaling and cell junctions were altered. DNA repair and cell adhesion molecules were affected by 124 mGy of radiation while DNA synthesis, apoptosis, metabolism, and neural differentiation were all affected by 496 mGy of radiation. These in vitro results suggest that 496 mGy radiation affects the development of neuronal progenitor cells while altered gene expression was observed at a radiation dose lower than 100 mGy. This study would contribute to the elucidation of the clinical and subclinical phenotypes of impaired neuronal development induced by chronic low-dose radiation. PMID:26795421

  17. Effects of Chronic Low-Dose Radiation on Human Neural Progenitor Cells

    Science.gov (United States)

    Katsura, Mari; Cyou-Nakamine, Hiromasa; Zen, Qin; Zen, Yang; Nansai, Hiroko; Amagasa, Shota; Kanki, Yasuharu; Inoue, Tsuyoshi; Kaneki, Kiyomi; Taguchi, Akashi; Kobayashi, Mika; Kaji, Toshiyuki; Kodama, Tatsuhiko; Miyagawa, Kiyoshi; Wada, Youichiro; Akimitsu, Nobuyoshi; Sone, Hideko

    2016-01-01

    The effects of chronic low-dose radiation on human health have not been well established. Recent studies have revealed that neural progenitor cells are present not only in the fetal brain but also in the adult brain. Since immature cells are generally more radiosensitive, here we investigated the effects of chronic low-dose radiation on cultured human neural progenitor cells (hNPCs) derived from embryonic stem cells. Radiation at low doses of 31, 124 and 496 mGy per 72 h was administered to hNPCs. The effects were estimated by gene expression profiling with microarray analysis as well as morphological analysis. Gene expression was dose-dependently changed by radiation. By thirty-one mGy of radiation, inflammatory pathways involving interferon signaling and cell junctions were altered. DNA repair and cell adhesion molecules were affected by 124 mGy of radiation while DNA synthesis, apoptosis, metabolism, and neural differentiation were all affected by 496 mGy of radiation. These in vitro results suggest that 496 mGy radiation affects the development of neuronal progenitor cells while altered gene expression was observed at a radiation dose lower than 100 mGy. This study would contribute to the elucidation of the clinical and subclinical phenotypes of impaired neuronal development induced by chronic low-dose radiation.

  18. Investigating the embryo/larval toxic and genotoxic effects of {gamma} irradiation on zebrafish eggs

    Energy Technology Data Exchange (ETDEWEB)

    Simon, O., E-mail: olivier.simon@irsn.fr [Laboratoire de Radioecologie et d' Ecotoxicologie, Institut de Radioprotection et de Surete Nucleaire, Cadarache, Bat 186, BP3, 13115 Saint-Paul-lez-Durance Cedex (France); Massarin, S. [Laboratoire de Modelisation Environnementale, Institut de Radioprotection et de Surete Nucleaire, Cadarache, Bat 159, BP3, 13115 Saint-Paul-lez-Durance Cedex (France); Coppin, F. [Laboratoire de Radioecologie et d' Ecotoxicologie, Institut de Radioprotection et de Surete Nucleaire, Cadarache, Bat 186, BP3, 13115 Saint-Paul-lez-Durance Cedex (France); Hinton, T.G. [Service d' Etude du Comportement des Radionucleides dans les Ecosystemes, Institut de Radioprotection et de Surete Nucleaire, Cadarache, Bat 159, BP3, 13115 Saint-Paul-lez-Durance Cedex (France); Gilbin, R. [Laboratoire de Radioecologie et d' Ecotoxicologie, Institut de Radioprotection et de Surete Nucleaire, Cadarache, Bat 186, BP3, 13115 Saint-Paul-lez-Durance Cedex (France)

    2011-11-15

    Eggs/larval of freshwater fish (Danio rerio) were exposed to low dose rates of external gamma radiation (from 1 to 1000 mGy d{sup -1}) over a 20-day period, with the objective of testing the appropriateness of the 10 mGy d{sup -1} guideline suggested by the IAEA. The present study examines different endpoints, mortality and hatching time and success of embryos as well as the genotoxicity of {gamma}-irradiations (after 48 h). The 20-day embryo-larval bioassay showed an enhanced larval resistance to starvation after chronic exposure to {gamma} irradiation (from low 1 mGy d{sup -1} to high dose rate 1000 mGy d{sup -1}) and an acceleration in hatching time. Gamma irradiation led to increased genotoxic damage Ito zebrafish egg (40-50% DNA in tail in Comet assay) from the lowest dose rate (1 mGy d{sup -1}). Possible mechanisms of {gamma} radiotoxicity and implications for radioprotection are discussed. - Highlights: > Relevant information on the {gamma} radiation impact on early life stage biota is scarce. > The eggs of zebrafish Danio rerio were selected as biological model. > We test the appropriateness of the 10 mGy d{sup -1} guideline (IAEA). > We observed effects measured at individual levels (starvation, hatching time). > Chronic gamma irradiation led to increased genotoxic damage to zebrafish egg. > {gamma} radiotoxicity mechanisms and implications for radioprotection are discussed.

  19. Nationwide survey of glandular tissue dose for establishment of breast cancer screening using mammography

    Energy Technology Data Exchange (ETDEWEB)

    Katoh, Tsuguhisa; Matsumoto, Mitsuomi [Tokyo Metropolitan Univ. of Health Sciences (Japan); Higashida, Yoshiharu [and others

    1999-06-01

    A nationwide survey was performed in an attempt to investigate the distribution of average glandular doses caused by mammography for breast cancer mass screening, and to utilize the data to determine the national guidance level for mammography. A phantom equivalent to a breast with a compressed thickness of 42 mm, and glass radio-photo luminescence dosimeters were sent to 104 institutions and facilities. The dosimeters were exposed using a method based on the protocols described in the Mammography Quality Control Manual. The returned dosimeters were then analyzed, and the beam qualities and the entrance surface exposure were determined. Using these values, the average glandular doses were estimated with an accuracy of {+-}8%. The doses ranged from 0.5 to 3.7 mGy. The mean dose and the standard deviation were 1.48 mGy and 0.52 mGy, respectively. In 91 facilities, the doses were less than 2 mGy. Regarding the technical factors for facilities which presented doses of 2 mGy or over, it seemed that the doses could be easily reduced to less than 2 mGy if the settings of the auto exposure controller (AEC), anti-scatter grid and/or the film-screen system were optimized. (author)

  20. Effects of Chronic Low-Dose Radiation on Human Neural Progenitor Cells.

    Science.gov (United States)

    Katsura, Mari; Cyou-Nakamine, Hiromasa; Zen, Qin; Zen, Yang; Nansai, Hiroko; Amagasa, Shota; Kanki, Yasuharu; Inoue, Tsuyoshi; Kaneki, Kiyomi; Taguchi, Akashi; Kobayashi, Mika; Kaji, Toshiyuki; Kodama, Tatsuhiko; Miyagawa, Kiyoshi; Wada, Youichiro; Akimitsu, Nobuyoshi; Sone, Hideko

    2016-01-22

    The effects of chronic low-dose radiation on human health have not been well established. Recent studies have revealed that neural progenitor cells are present not only in the fetal brain but also in the adult brain. Since immature cells are generally more radiosensitive, here we investigated the effects of chronic low-dose radiation on cultured human neural progenitor cells (hNPCs) derived from embryonic stem cells. Radiation at low doses of 31, 124 and 496 mGy per 72 h was administered to hNPCs. The effects were estimated by gene expression profiling with microarray analysis as well as morphological analysis. Gene expression was dose-dependently changed by radiation. By thirty-one mGy of radiation, inflammatory pathways involving interferon signaling and cell junctions were altered. DNA repair and cell adhesion molecules were affected by 124 mGy of radiation while DNA synthesis, apoptosis, metabolism, and neural differentiation were all affected by 496 mGy of radiation. These in vitro results suggest that 496 mGy radiation affects the development of neuronal progenitor cells while altered gene expression was observed at a radiation dose lower than 100 mGy. This study would contribute to the elucidation of the clinical and subclinical phenotypes of impaired neuronal development induced by chronic low-dose radiation.

  1. Breast dose reduction for chest CT by modifying the scanning parameters based on the pre-scan size-specific dose estimate (SSDE)

    Energy Technology Data Exchange (ETDEWEB)

    Kidoh, Masafumi; Utsunomiya, Daisuke; Oda, Seitaro; Nakaura, Takeshi; Yuki, Hideaki; Hirata, Kenichiro; Namimoto, Tomohiro; Sakabe, Daisuke; Hatemura, Masahiro; Yamashita, Yasuyuki [Kumamoto University, Department of Diagnostic Radiology, Faculty of Life Sciences, Honjo, Kumamoto (Japan); Funama, Yoshinori [Kumamoto University, Department of Medical Physics, Faculty of Life Sciences, Honjo, Kumamoto (Japan)

    2017-06-15

    To investigate the usefulness of modifying scanning parameters based on the size-specific dose estimate (SSDE) for a breast-dose reduction for chest CT. We scanned 26 women with a fixed volume CT dose index (CTDI{sub vol}) (15 mGy) and another 26 with a fixed SSDE (15 mGy) protocol (protocol 1 and 2, respectively). In protocol 2, tube current was calculated based on the patient habitus obtained on scout images. We compared the mean breast dose and the inter-patient breast dose variability and performed linear regression analysis of the breast dose and the body mass index (BMI) of the two protocols. The mean breast dose was about 35 % lower under protocol 2 than protocol 1 (10.9 mGy vs. 16.8 mGy, p < 0.01). The inter-patient breast dose variability was significantly lower under protocol 2 than 1 (1.2 mGy vs. 2.5 mGy, p < 0.01). We observed a moderate negative correlation between the breast dose and the BMI under protocol 1 (r = 0.43, p < 0.01); there was no significant correlation (r = 0.06, p = 0.35) under protocol 2. The SSDE-based protocol achieved a reduction in breast dose and in inter-patient breast dose variability. (orig.)

  2. SU-F-I-46: Optimizing Dose Reduction in Adult Head CT Protocols While Maintaining Image Quality in Postmortem Head Scans

    Energy Technology Data Exchange (ETDEWEB)

    Lipnharski, I; Carranza, C; Quails, N; Correa, N; Rajderkar, D; Bennett, J; Rill, L; Arreola, M [University of Florida, Gainesville, FL (United States)

    2016-06-15

    Purpose: To optimize adult head CT protocol by reducing dose to an appropriate level while providing CT images of diagnostic quality. Methods: Five cadavers were scanned from the skull base to the vertex using a routine adult head CT protocol (120 kVp, 270 mA, 0.75 s rotation, 0.5 mm × 32 detectors, 70.8 mGy CTDIvol) followed by seven reduced-dose protocols with varying combinations of reduced tube current, reduced rotation time, and increased detectors with CTDIvol ranging from 38.2 to 65.6 mGy. Organ doses were directly measured with 21 OSL dosimeters placed on the surface and implanted in the head by a neurosurgeon. Two neuroradiologists assessed grey-white matter differentiation, fluid space, ventricular size, midline shift, brain mass, edema, ischemia, and skull fractures on a three point scale: (1) Unacceptable, (2) Borderline Acceptable, and (3) Acceptable. Results: For the standard scan, doses to the skin, lens of the eye, salivary glands, thyroid, and brain were 37.55 mGy, 49.65 mGy, 40.67 mGy, 4.63 mGy, and 27.33 mGy, respectively. Two cadavers had cerebral edema due to changing dynamics of postmortem effects, causing the grey-white matter differentiation to appear less distinct. Two cadavers with preserved grey-white matter received acceptable scores for all image quality features for the protocol with a CTDIvol of 57.3 mGy, allowing organ dose savings ranging from 34% to 45%. One cadaver allowed for greater dose reduction for the protocol with a CTDIvol of 42 mGy. Conclusion: Efforts to optimize scan protocol should consider both dose and clinical image quality. This is made possible with postmortem subjects, whose brains are similar to patients, allowing for an investigation of ideal scan parameters. Radiologists at our institution accepted scan protocols acquired with lower scan parameters, with CTDIvol values closer to the American College of Radiology’s (ACR) Achievable Dose level of 57 mGy.

  3. SU-F-207-14: Low Contrast Detectability (LCD) at Different Diagnostic Reference Levels for Adult Abdominal CT Procedures

    Energy Technology Data Exchange (ETDEWEB)

    Mahmood, U; Erdi, Y [Mem Sloan-Kettering Cancer Ctr, New York, NY (United States)

    2015-06-15

    Purpose Using diagnostic reference levels (DRL) to optimize CT protocols has potential to reduce radiation dose and meet regulatory requirements. However, DRL’s tend to be misconstrued as dose limits, are typically designed for specific patient populations, and are assumed to have acceptable image quality (AIQ) associated with them. To determine the image quality that is associated with established DRL’s for adult abdominal CT studies, a LCD phantom study was employed. Methods: A CT phantom (CIRS) containing three columns of 7 spherical targets, ranging from 10mm to 2.4 mm, that are 5, 10, and 20 HU below the background (HUBB) matrix was scanned with a GE HD750 64 slice scanner. The phantom was scanned at the NEXT 2006 25th CTDIvol of 12 mGy, the NCRP 172 achievable dose (AD) CTDIvol of 17 mGy and 75th CTDIvol of 25 mGy and at the ACR recommended CTDIvol of 25 mGy. It was also scanned at a CTDIvol 20% greater than the AD at 20 mGy and the ACR maximum threshold of 30 mGy. Results: At the NEXT 2006 25th percentile CTDIvol of 12 mGy, a 6.3 mm low contrast lesion was detectable in the 20 HUBB; 6.3 mm in the 10 HUBB and 10 mm in the 5 HUBB column. Increasing the CTDIvol to the NCRP 172 AD of 17 mGy, an additional 4.8 mm lesion was visualized in the 20 HUBB column. At 20 mGy, an additional 4.8 mm lesion was detectable in the 10 HUBB column. No further lesions were visible between 20 and 30 mGy. However, conspicuity of all lesions increased with each additional step up in CTDI. Conclusion: Optimizing radiation dose to achieve AIQ is a critical aspect of any dose optimization committee. Hence, judicious monitoring of radiation exposure to patients has to be balanced with diagnostic image quality.

  4. SU-E-I-28: Evaluating the Organ Dose From Computed Tomography Using Monte Carlo Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Ono, T; Araki, F [Faculty of Life Sciences, Kumamoto University, Kumamoto (Japan)

    2014-06-01

    Purpose: To evaluate organ doses from computed tomography (CT) using Monte Carlo (MC) calculations. Methods: A Philips Brilliance CT scanner (64 slice) was simulated using the GMctdospp (IMPS, Germany) based on the EGSnrc user code. The X-ray spectra and a bowtie filter for MC simulations were determined to coincide with measurements of half-value layer (HVL) and off-center ratio (OCR) profile in air. The MC dose was calibrated from absorbed dose measurements using a Farmer chamber and a cylindrical water phantom. The dose distribution from CT was calculated using patient CT images and organ doses were evaluated from dose volume histograms. Results: The HVLs of Al at 80, 100, and 120 kV were 6.3, 7.7, and 8.7 mm, respectively. The calculated HVLs agreed with measurements within 0.3%. The calculated and measured OCR profiles agreed within 3%. For adult head scans (CTDIvol) =51.4 mGy), mean doses for brain stem, eye, and eye lens were 23.2, 34.2, and 37.6 mGy, respectively. For pediatric head scans (CTDIvol =35.6 mGy), mean doses for brain stem, eye, and eye lens were 19.3, 24.5, and 26.8 mGy, respectively. For adult chest scans (CTDIvol=19.0 mGy), mean doses for lung, heart, and spinal cord were 21.1, 22.0, and 15.5 mGy, respectively. For adult abdominal scans (CTDIvol=14.4 mGy), the mean doses for kidney, liver, pancreas, spleen, and spinal cord were 17.4, 16.5, 16.8, 16.8, and 13.1 mGy, respectively. For pediatric abdominal scans (CTDIvol=6.76 mGy), mean doses for kidney, liver, pancreas, spleen, and spinal cord were 8.24, 8.90, 8.17, 8.31, and 6.73 mGy, respectively. In head scan, organ doses were considerably different from CTDIvol values. Conclusion: MC dose distributions calculated by using patient CT images are useful to evaluate organ doses absorbed to individual patients.

  5. Dosimetric evaluation of X-ray examinations of paranasal sinuses in pediatric patients

    Energy Technology Data Exchange (ETDEWEB)

    Cantalupo, Beatriz de Lucena Villa-Chan; Andrade, Marcos Ely Almeida; Barros, Vinicius Saito Monteiro de; Khoury, Helen Jamil [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Xavier, Aline Carvalho da Silva [Pontificia Universidad Catolica de Chile, Santiago (Chile); Silva, Clemanzy Mariano Leandro da, E-mail: beatrizvillachan@gmail.com [Faculdade Integrada de Pernambuco (FACUPE), Recife, PE (Brazil)

    2016-03-15

    Objective: to estimate the entrance surface air kerma (K{sub a,e}) and air kerma in the region of radiosensitive organs in radiographs of pediatric paranasal sinuses. Materials and methods: patient data and irradiation parameters were collected in examinations of the paranasal sinuses in children from 0 to 15 years of age at two children's hospitals in the city of Recife, PE, Brazil. We estimated the K{sub a,e} using the X-ray tube outputs and selected parameters. To estimate the air kerma values in the regions of the eyes and thyroid, we used thermoluminescent dosimeters. Results: the K{sub a,e} values ranged from 0.065 to 1.446 mGy in cavum radiographs, from 0.104 to 7.298 mGy in Caldwell views, and from 0.113 to 7.824 mGy in Waters views. Air kerma values in the region of the eyes ranged from 0.001 to 0.968 mGy in cavum radiographs and from 0.011 to 0.422 mGy in Caldwell and Waters views . In the thyroid region, air kerma values ranged from 0.005 to 0.932 mGy in cavum radiographs and from 0.002 to 0.972 mGy in Caldwell and Waters views. Conclusion: the radiation levels used at the institutions under study were higher than those recommended in international protocols. We recommend that interventions be initiated in order to reduce patient exposure to radiation and therefore the risks associated with radiological examination of the paranasal sinuses. (author)

  6. Dosimetric evaluation of X-ray examinations of paranasal sinuses in pediatric patients

    Directory of Open Access Journals (Sweden)

    Beatriz de Lucena Villa-Chan Cantalupo

    2016-04-01

    Full Text Available Abstract Objective: To estimate the entrance surface air kerma (Ka,e and air kerma in the region of radiosensitive organs in radiographs of pediatric paranasal sinuses. Materials and Methods: Patient data and irradiation parameters were collected in examinations of the paranasal sinuses in children from 0 to 15 years of age at two children's hospitals in the city of Recife, PE, Brazil. We estimated the Ka,e using the X-ray tube outputs and selected parameters. To estimate the air kerma values in the regions of the eyes and thyroid, we used thermoluminescent dosimeters. Results: The Ka,e values ranged from 0.065 to 1.446 mGy in cavum radiographs, from 0.104 to 7.298 mGy in Caldwell views, and from 0.113 to 7.824 mGy in Waters views. Air kerma values in the region of the eyes ranged from 0.001 to 0.968 mGy in cavum radiographs and from 0.011 to 0.422 mGy in Caldwell and Waters views . In the thyroid region, air kerma values ranged from 0.005 to 0.932 mGy in cavum radiographs and from 0.002 to 0.972 mGy in Caldwell and Waters views. Conclusion: The radiation levels used at the institutions under study were higher than those recommended in international protocols. We recommend that interventions be initiated in order to reduce patient exposure to radiation and therefore the risks associated with radiological examination of the paranasal sinuses.

  7. Dosimetric evaluation of X-ray examinations of paranasal sinuses in pediatric patients*

    Science.gov (United States)

    Cantalupo, Beatriz de Lucena Villa-Chan; Xavier, Aline Carvalho da Silva; da Silva, Clemanzy Mariano Leandro; Andrade, Marcos Ely Almeida; de Barros, Vinícius Saito Monteiro; Khoury, Helen Jamil

    2016-01-01

    Objective To estimate the entrance surface air kerma (Ka,e) and air kerma in the region of radiosensitive organs in radiographs of pediatric paranasal sinuses. Materials and Methods Patient data and irradiation parameters were collected in examinations of the paranasal sinuses in children from 0 to 15 years of age at two children's hospitals in the city of Recife, PE, Brazil. We estimated the Ka,e using the X-ray tube outputs and selected parameters. To estimate the air kerma values in the regions of the eyes and thyroid, we used thermoluminescent dosimeters. Results The Ka,e values ranged from 0.065 to 1.446 mGy in cavum radiographs, from 0.104 to 7.298 mGy in Caldwell views, and from 0.113 to 7.824 mGy in Waters views. Air kerma values in the region of the eyes ranged from 0.001 to 0.968 mGy in cavum radiographs and from 0.011 to 0.422 mGy in Caldwell and Waters views . In the thyroid region, air kerma values ranged from 0.005 to 0.932 mGy in cavum radiographs and from 0.002 to 0.972 mGy in Caldwell and Waters views. Conclusion The radiation levels used at the institutions under study were higher than those recommended in international protocols. We recommend that interventions be initiated in order to reduce patient exposure to radiation and therefore the risks associated with radiological examination of the paranasal sinuses. PMID:27141129

  8. Determining and Managing Fetal Radiation Dose from Diagnostic Radiology Procedures in Turkey

    Science.gov (United States)

    Cavdar, Iffet; Seven, Mehmet; Uslu, Lebriz; Yeyin, Nami; Tanyildizi, Handan; Abuqbeitah, Mohammad; Acikgoz, A. Serdar; Tuten, Abdullah; Demir, Mustafa

    2015-01-01

    Objective We intended to calculate approximate fetal doses in pregnant women who underwent diagnostic radiology procedures and to evaluate the safety of their pregnancies. Materials and Methods We contacted hospitals in different cities in Turkey where requests for fetal dose calculation are usually sent. Fetal radiation exposure was calculated for 304 cases in 218 pregnant women with gestational ages ranging from 5 days to 19 weeks, 2 days. FetDose software (ver. 4.0) was used in fetal dose calculations for radiographic and computed tomography (CT) procedures. The body was divided into three zones according to distance from the fetus. The first zone consisted of the head area, the lower extremities below the knee, and the upper extremities; the second consisted of the cervicothoracic region and upper thighs; and the third consisted of the abdominopelvic area. Fetal doses from radiologic procedures between zones were compared using the Kruskal-Wallis test and a Bonferroni-corrected Mann-Whitney U-test. Results The average fetal doses from radiography and CT in the first zone were 0.05 ± 0.01 mGy and 0.81 ± 0.04 mGy, respectively; 0.21 ± 0.05 mGy and 1.77 ± 0.22 mGy, respectively, in the second zone; and 6.42 ± 0.82 mGy and 22.94 ± 1.28 mGy, respectively, in the third zone (p < 0.001). Our results showed that fetal radiation exposures in our group of pregnant women did not reach the level (50 mGy) that is known to increase risk for congenital anomalies. Conclusion Fetal radiation exposure in the diagnostic radiology procedures in our study did not reach risk levels that might have indicated abortion. PMID:26576117

  9. Low dose radiation risks for women surviving the a-bombs in Japan: generalized additive model.

    Science.gov (United States)

    Dropkin, Greg

    2016-11-24

    Analyses of cancer mortality and incidence in Japanese A-bomb survivors have been used to estimate radiation risks, which are generally higher for women. Relative Risk (RR) is usually modelled as a linear function of dose. Extrapolation from data including high doses predicts small risks at low doses. Generalized Additive Models (GAMs) are flexible methods for modelling non-linear behaviour. GAMs are applied to cancer incidence in female low dose subcohorts, using anonymous public data for the 1958 - 1998 Life Span Study, to test for linearity, explore interactions, adjust for the skewed dose distribution, examine significance below 100 mGy, and estimate risks at 10 mGy. For all solid cancer incidence, RR estimated from 0 - 100 mGy and 0 - 20 mGy subcohorts is significantly raised. The response tapers above 150 mGy. At low doses, RR increases with age-at-exposure and decreases with time-since-exposure, the preferred covariate. Using the empirical cumulative distribution of dose improves model fit, and capacity to detect non-linear responses. RR is elevated over wide ranges of covariate values. Results are stable under simulation, or when removing exceptional data cells, or adjusting neutron RBE. Estimates of Excess RR at 10 mGy using the cumulative dose distribution are 10 - 45 times higher than extrapolations from a linear model fitted to the full cohort. Below 100 mGy, quasipoisson models find significant effects for all solid, squamous, uterus, corpus, and thyroid cancers, and for respiratory cancers when age-at-exposure > 35 yrs. Results for the thyroid are compatible with studies of children treated for tinea capitis, and Chernobyl survivors. Results for the uterus are compatible with studies of UK nuclear workers and the Techa River cohort. Non-linear models find large, significant cancer risks for Japanese women exposed to low dose radiation from the atomic bombings. The risks should be reflected in protection standards.

  10. Determining and managing fetal radiation dose from diagnostic radiology procedures in Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Ozbayrak, Mustafa; Cavdar, Iffet; Seven, Mehmet; Uslu, Lebriz; Yeyin, Nami; Tanyildizi, Handan; Abuqbeitah, Mohammad; Acikgoz, A. Serdar; Tuten, Abdullah; Demir, Mustafa [Istanbul University, Istanbul (Turkmenistan)

    2015-12-15

    We intended to calculate approximate fetal doses in pregnant women who underwent diagnostic radiology procedures and to evaluate the safety of their pregnancies. We contacted hospitals in different cities in Turkey where requests for fetal dose calculation are usually sent. Fetal radiation exposure was calculated for 304 cases in 218 pregnant women with gestational ages ranging from 5 days to 19 weeks, 2 days. FetDose software (ver. 4.0) was used in fetal dose calculations for radiographic and computed tomography (CT) procedures. The body was divided into three zones according to distance from the fetus. The first zone consisted of the head area, the lower extremities below the knee, and the upper extremities; the second consisted of the cervicothoracic region and upper thighs; and the third consisted of the abdominopelvic area. Fetal doses from radiologic procedures between zones were compared using the Kruskal-Wallis test and a Bonferroni-corrected Mann-Whitney U-test. The average fetal doses from radiography and CT in the first zone were 0.05 ± 0.01 mGy and 0.81 ± 0.04 mGy, respectively; 0.21 ± 0.05 mGy and 1.77 ± 0.22 mGy, respectively, in the second zone; and 6.42 ± 0.82 mGy and 22.94 ± 1.28 mGy, respectively, in the third zone (p < 0.001). Our results showed that fetal radiation exposures in our group of pregnant women did not reach the level (50 mGy) that is known to increase risk for congenital anomalies. Fetal radiation exposure in the diagnostic radiology procedures in our study did not reach risk levels that might have indicated abortion.

  11. The Berry-Keating Hamiltonian and the local Riemann hypothesis

    Science.gov (United States)

    Srednicki, Mark

    2011-07-01

    The local Riemann hypothesis states that the zeros of the Mellin transform of a harmonic-oscillator eigenfunction (on a real or p-adic configuration space) have a real part 1/2. For the real case, we show that the imaginary parts of these zeros are the eigenvalues of the Berry-Keating Hamiltonian \\hat{H}_BK=(\\hat{x}\\hat{p}+\\hat{p}\\hat{x})/2 projected onto the subspace of oscillator eigenfunctions of a lower level. This gives a spectral proof of the local Riemann hypothesis for the reals, in the spirit of the Hilbert-Pólya conjecture. The p-adic case is also discussed.

  12. On the Physics of the Riemann Zeros

    Science.gov (United States)

    He, Yang-Hui; Jejjala, Vishnu; Minic, Djordje

    2013-12-01

    We discuss a formal derivation of an integral expression for the Li coefficients associated with the Riemann ξ-function which, in particular, indicates that their positivity criterion is obeyed, whereby entailing the criticality of the non-trivial zeros. We conjecture the validity of this and related expressions without the need for the Riemann Hypothesis and discuss a physical interpretation of this result within the Hilbert-Pólya approach. In this context we also outline a relation between string theory and the Riemann Hypothesis.

  13. Las funciones como modelo matemático: informe final de práctica docente

    OpenAIRE

    Carmona Gaviria, Alvaro Diego

    2012-01-01

    La Práctica Docente consistió en una experiencia de aula para la enseñanza de las matemáticas, fundamentada en la estrategia metodológica de la solución de problemas bajo el enfoque del aprendizaje significativo. El interés del trabajo se centra, específicamente, en la enseñanza de funciones reales como modelo matemático, mostrando algunos criterios para modelar problemas bajo una propuesta de Solución de Problemas (Pólya, 1957) por medio del razonamiento de tipo inductivo (Ausubel, 1968). E...

  14. Nonclassical degrees of freedom in the Riemann Hamiltonian.

    Science.gov (United States)

    Srednicki, Mark

    2011-09-02

    The Hilbert-Pólya conjecture states that the imaginary parts of the zeros of the Riemann zeta function are eigenvalues of a quantum Hamiltonian. If so, conjectures by Katz and Sarnak put this Hamiltonian in the Altland-Zirnbauer universality class C. This implies that the system must have a nonclassical two-valued degree of freedom. In such a system, the dominant primitive periodic orbits contribute to the density of states with a phase factor of -1. This resolves a previously mysterious sign problem with the oscillatory contributions to the density of the Riemann zeros.

  15. A New Proof of the Expected Frequency Spectrum under the Standard Neutral Model.

    Science.gov (United States)

    Hudson, Richard R

    2015-01-01

    The sample frequency spectrum is an informative and frequently employed approach for summarizing DNA variation data. Under the standard neutral model the expectation of the sample frequency spectrum has been derived by at least two distinct approaches. One relies on using results from diffusion approximations to the Wright-Fisher Model. The other is based on Pólya urn models that correspond to the standard coalescent model. A new proof of the expected frequency spectrum is presented here. It is a proof by induction and does not require diffusion results and does not require the somewhat complex sums and combinatorics of the derivations based on urn models.

  16. Pointwise Multipliers of Triebel-Lizorkin Spaces on Carnot-Carathéodory Spaces

    Directory of Open Access Journals (Sweden)

    Yanchang Han

    2012-01-01

    Full Text Available Let be a Carnot-Carathéodory space, namely, is a smooth manifold, is a control, or Carnot-Carathéodory, metric induced by a collection of vector fields of finite type. is a nonnegative Borel regular measure on satisfying that there exists constant such that for all and  diam , . Using the discrete Calderón reproducing formula and the Plancherel-Pôlya characterization of the inhomogeneous Triebel-Lizorkin spaces developed in Han et al., in press and Han et al., 2008, pointwise multipliers of inhomogeneous Triebel-Lizorkin spaces are obtained.

  17. MAGRITTE: an instrument suite for the solar atmospheric imaging assembly (AIA) aboard the Solar Dynamics Observatory

    OpenAIRE

    Rochus, Pierre; Defise, Jean-Marc; Halain, Jean-Philippe; Jamar, Claude; Mazy, Emmanuel; Rossi, Laurence; Thibert, Tanguy; Clette, Frederic; Cugnon, Pierre; Berghmans, David; Hochedez, Jean-Francois E; Delaboudiniere, Jean-Pierre; Auchere, Frederic; Mercier, Raymond; Ravet, Marie-Francoise

    2004-01-01

    The Solar Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory will characterize the dynamical evolution of the solar plasma from the chromosphere to the corona, and will follow the connection of plasma dynamics with magnetic activity throughout the solar atmosphere. The AIA consists of 7 high-resolution imaging telescopes in the following spectral bandpasses: 1215Å. Ly-a, 304 Å He II, 629 Å OV, 465 Å Ne VII, 195 Å Fe XII (includes Fe XXIV), 284 Å Fe XV, and 335 Å Fe XVI. ...

  18. Refined counting of necklaces in one-loop N=4 SYM

    Science.gov (United States)

    Suzuki, Ryo

    2017-06-01

    We compute the grand partition function of N=4 SYM at one-loop in the SU(2) sector with general chemical potentials, extending the results of Pólya's theorem. We make use of finite group theory, applicable to all orders of perturbative 1 /N c expansion. We show that only the planar terms contribute to the grand partition function, which is therefore equal to the grand partition function of an ensemble of {XXX}_{1/2} spin chains. We discuss how Hagedorn temperature changes on the complex plane of chemical potentials.

  19. Quantum state revivals in quantum walks on cycles

    Directory of Open Access Journals (Sweden)

    Phillip R. Dukes

    2014-01-01

    Full Text Available Recurrence in the classical random walk is well known and described by the Pólya number. For quantum walks, recurrence is similarly understood in terms of the probability of a localized quantum walker to return to its origin. Under certain circumstances the quantum walker may also return to an arbitrary initial quantum state in a finite number of steps. Quantum state revivals in quantum walks on cycles using coin operators which are constant in time and uniform across the path have been described before but only incompletely. In this paper we find the general conditions for which full-quantum state revival will occur.

  20. Presentación del Libro, “Ciencia, Mitos y Dioses”.

    OpenAIRE

    Guillermo Sánchez Medina

    2006-01-01

    Dedico esta obra a todos aquellos que necesitan preguntarse algo más. Agradezco a mi señora Lya Focaccio, quien durante años ha sabido comprender mis curiosidades. Mi gratitud a todos los que fueron partícipes de la elaboración de este trabajo, en especial a mi amigo Académico Adolfo De Francisco Zea”. En el inicio de la presentación el Académico Sánchez Medina definió los términos del título de la obra, los cuales contienen la esencia de la obra: Ciencia, es...

  1. Discrete dispersion models and their Tweedie asymptotics

    DEFF Research Database (Denmark)

    Jørgensen, Bent; Kokonendji, Célestin C.

    2016-01-01

    in this approach, whereas several overdispersed discrete distributions, such as the Neyman Type A, Pólya-Aeppli, negative binomial and Poisson-inverse Gaussian, turn out to be Poisson-Tweedie factorial dispersion models with power dispersion functions, analogous to ordinary Tweedie exponential dispersion models...... with power variance functions. Using the factorial cumulant generating function as tool, we introduce a dilation operation as a discrete analogue of scaling, generalizing binomial thinning. The Poisson-Tweedie factorial dispersion models are closed under dilation, which in turn leads to a Poisson...

  2. ERKÜ valimiste tulemused

    Index Scriptorium Estoniae

    2006-01-01

    8. aprilli koosolekul kinnitas valimiste peakomitee XIX Esinduskogu liikmed: Mati Kõiva, Ylo Anson, Juhan Simonson, Airi Vaga, Gilda M. Karu, Taavo Virkhaus, Marju Rink-Abel, Markus Vaga, Eric Suuberg, Endel Reinpõld, Jaak Juhansoo, Ülle Ederma, Lya Karm, Heino Jõgis, Kersti Linask, Jaak Rakfeldt, Erik Puskar, Jüri Linask, Viiu Vanderer, Andres Kurrik, Mati Valdek Laan, Ilmar Vanderer, Henno Uus, Jüri Tults, Urmas Wompa, Astrid Jaanson, Jüri Virkus, Lilian G. G. Bein, Tiina Harris, Tõnu Vanderer

  3. Chatbot-teknologia : sähköinen kaupankäynti ja asiakaspalvelu

    OpenAIRE

    2015-01-01

    Tutkimusorganisaatio Gartnerin tutkimuksissa on arvioitu, että vuonna 2020 yli 85 % asiakaspalvelutapahtumista hoituu ilman ihmisen avustusta, jolloin esimerkiksi Yhdysvaltojen 18 miljoonasta myyjästä on jäljellä enää vain noin 4 miljoonaa. Väitettä tukee myös virtuaalisten assistenttien tekemä myynti, mikä on kasvanut 2010-luvulla vuosittain 50 %. Tässä tutkielmassa käsitellään tekoälyä hyödyntävää virtuaalista assistenttia, eli chatbottia. Tutkielman tavoitteena on...

  4. Operation of Ge- and GaAs-tunnel diodes under the influence of electron beams

    Science.gov (United States)

    El-Basit, W. Abd; Awad, Z. I. M.; Kamh, S. A.; Soliman, F. A. S.

    2017-02-01

    Nuclear radiation plays a very negative role in the semiconductor devices functionality, mainly when particular semiconductor devices are exposed to an extreme type of radiation. Tunneling is an important aspect of charge transport in semiconductor and molecular devices. So, the effect of electron irradiation on the current-voltage (I-V) characteristics of Germanium (Ge) and Gallium Arsenide (GaAs) tunneling diodes are reported at room temperature before and after irradiation. Electrons exposure, up to 3.73 My, of the tunnel diodes leads to a pronounced change in their electrical characteristics where the rate of change of the peak- and valley-currents, for Ge and GaAs tunnel diodes, due to electron exposure are shown to be about +53.6, +142 µA/MGy and +29.4, +53.6 µA/MGy, respectively. On the other hand, for the same irradiation doses, the rate of change of the valley- and forward-voltages and output power are shown to be about -44.9, -15.9 and -6.7 mW/MGy, for Ge tunnel diodes, respectively. While, GaAs samples, reported values of -81, -83 mV/MGy and -11.6 mW/MGy are observed. Besides, the peak to valley current ratio of both Ge- and GaAs TDs are proved to decrease due to electrons exposure, with damping ratios of about 78 and 81%, respectively.

  5. Comparing five different iterative reconstruction algorithms for computed tomography in an ROC study

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Kristin; Martinsen, Anne Catrine T. [Rikshospitalet, The Intervention Centre, Postboks 4950, Oslo (Norway); University of Oslo, lnstitute of Physics, Oslo (Norway); Tingberg, Anders [Lund University, Skaane University Hospital, Department of Medical Radiation Physics, Malmoe (Sweden); Aaloekken, Trond Mogens [Rikshospitalet, Department of Radiology and Nuclear Medicine, Postboks 4950, Oslo (Norway); Fosse, Erik [Rikshospitalet, The Intervention Centre, Postboks 4950, Oslo (Norway); University of Oslo, lnstitute of Clinical Medicine, Oslo (Norway)

    2014-12-15

    The purpose of this study was to evaluate lesion conspicuity achieved with five different iterative reconstruction techniques from four CT vendors at three different dose levels. Comparisons were made of iterative algorithm and filtered back projection (FBP) among and within systems. An anthropomorphic liver phantom was examined with four CT systems, each from a different vendor. CTDI{sub vol} levels of 5 mGy, 10 mGy and 15 mGy were chosen. Images were reconstructed with FBP and the iterative algorithm on the system. Images were interpreted independently by four observers, and the areas under the ROC curve (AUCs) were calculated. Noise and contrast-to-noise ratios (CNR) were measured. One iterative algorithm increased AUC (0.79, 0.95, and 0.97) compared to FBP (0.70, 0.86, and 0.93) at all dose levels (p < 0.001 and p = 0.047). Another algorithm increased AUC from 0.78 with FBP to 0.84 (p = 0.007) at 5 mGy. Differences at 10 and 15 mGy were not significant (p-values: 0.084-0.883). Three algorithms showed no difference in AUC compared to FBP (p-values: 0.008-1.000). All of the algorithms decreased noise (10-71 %) and improved CNR. Only two algorithms improved lesion detection, even though noise reduction was shown with all algorithms. (orig.)

  6. Effect of gamma irradiation at intermediate doses on the performance of reverse osmosis membranes

    Science.gov (United States)

    Combernoux, Nicolas; Labed, Véronique; Schrive, Luc; Wyart, Yvan; Carretier, Emilie; Moulin, Philippe

    2016-07-01

    The goal of this study is to explain the degradation of Polyamide (PA) composite reverse osmosis membrane (RO) in function of the irradiation dose. Irradiations were performed with a gamma 60Co source in wet conditions and under oxygen atmosphere. For different doses of 0.2 and 0.5 MGy with a constant dose rate of 0.5 kGy h-1, RO membranes performances (NaCl retention, permeability) were studied before and after irradiation. ATR-FTIR, ion chromatography and gas chromatography were used to characterize structural modification. Results showed that the permeability of RO membranes irradiated at 0.2 MGy exhibited a small decrease, related to scissions of the PVA coating. However, retention did not change at this dose. At 0.5 MGy, permeability showed a large increase of a factor around 2 and retention began to decrease from 99% to 95%. Chromatography measurements revealed a strong link between permselectivity properties variation, ion leakage and oxygen consumption. Add to ATR-FTIR observations, these results emphasized that the cleavages of amide and ester bonds were observed at 0.5 MGy, more precisely the loss of hydrogen bonds between polyamide chains. By different analysis, modifications of the polysulfone layer occur until a dose of 0.2 MGy.

  7. Increased apoptosis and DNA double-strand breaks in the embryonic mouse brain in response to very low-dose X-rays but not 50 Hz magnetic fields.

    Science.gov (United States)

    Saha, Shreya; Woodbine, Lisa; Haines, Jackie; Coster, Margaret; Ricket, Nicole; Barazzuol, Lara; Ainsbury, Elizabeth; Sienkiewicz, Zenon; Jeggo, Penny

    2014-11-06

    The use of X-rays for medical diagnosis is enhancing exposure to low radiation doses. Exposure to extremely low-frequency electromagnetic or magnetic fields is also increasing. Epidemiological studies show consistent associations of childhood leukaemia with exposure to magnetic fields but any causal relationship is unclear. A limitation in assessing the consequence of such exposure is the availability of sensitive assays. The embryonic neuronal stem and progenitor cell compartments are radiosensitive tissues. Using sensitive assays, we report a statistically significant increase in DNA double-strand break (DSB) formation and apoptosis in the embryonic neuronal stem cell compartment following in utero exposure to 10-200 mGy X-rays. Both endpoints show a linear response. We also show that DSB repair is delayed following exposure to doses below 50 mGy compared with 100 mGy. Thus, we demonstrate in vivo consequences of low-dose radiation. In contrast to these impacts, we did not observe any significant induction of DSBs or apoptosis following exposure to 50 Hz magnetic fields (100 or 300 µT). We conclude that any DSB induction by treatment with magnetic fields is lower than following exposure to 10 mGy X-rays. For comparison, certain procedures involving computed tomography scanning are equivalent to 1-5 mGy X-rays.

  8. Clinical indications and radiation doses to the conceptus associated with CT imaging in pregnancy: a retrospective study

    Energy Technology Data Exchange (ETDEWEB)

    Woussen, S.; Vanbeckevoort, D.; Bosmans, H.; Oyen, R. [University Hospitals Leuven, Department of Radiology, Leuven (Belgium); Lopez-Rendon, X.; Zanca, F. [University Hospitals Leuven, Department of Imaging and Pathology, Leuven (Belgium)

    2016-04-15

    To perform an internal audit at a university hospital with the aim of evaluating the number, clinical indication and operating procedure of computed tomography (CT) performed on pregnant patients and of estimating the radiation doses to the conceptus. A retrospective review was conducted of all CT examinations performed in a single centre on pregnant patients between January 2008 and July 2013. The radiation doses to the conceptus were estimated. The results were compared with published data. The number of CT examinations during pregnancy increased from 3-4 per year in 2008-2011 to 11 per year in 2012. The mean estimated conceptus radiation dose was considered negligible for CT of the head and cervical spine, being less than 0.01 mGy, and for CT of the chest, less than 0.1 mGy. The estimated conceptus radiation dose from abdominopelvic CT was on average 28.7 mGy (range 6.7-60.5 mGy). The number of CT scans of pregnant patients increased threefold during the last few years. Most clinical indications and doses were in line with good clinical practice and literature; only in two cases the dose to the conceptus was higher than 50 mGy. (orig.)

  9. Radiation induced micrencephaly in guinea pigs

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, L.K.; Johnston, D.A.; Felleman, D.J.

    1991-01-01

    A brain weight deficit of about 70 mg was induced at doses of approximately 75-mGy and a deficit of 60 mg was induced at 100 mGy. This confirms the effects projected and observed by Wanner and Edwards. Although the data do not demonstrate a clear dose-response relationship between the 75-mGy and 100-mGy groups, the data are statistically consistent with a dose-response effect because of the overlapping confidence intervals. The lack of a statistically significant observation is most likely related to the small difference in doses and the limited numbers of animals examined. There are several factors that can influence the brain weight of guinea pig pups, such as caging and housing conditions, the sex of the animal, and litter size. These should be taken into account for accurate analysis. Dam weight did not appear to have a significant effect. The confirmation of a micrencephalic effect induced x rays at doses of 75-mGy during this late embryonic stage of development is consistent with the findings of small head size induced in those exposed prior to the eight week of conception at Hiroshima. This implies a mechanism for micrencephaly different from those previously suggested and lends credence to a causal relation between radiation and small head size in humans at low doses as reported by Miller and Mulvihill. 16 refs., 13 tabs.

  10. Imaging lobular breast carcinoma: comparison of synchrotron radiation DEI-CT technique with clinical CT, mammography and histology

    Science.gov (United States)

    Fiedler, S.; Bravin, A.; Keyriläinen, J.; Fernández, M.; Suortti, P.; Thomlinson, W.; Tenhunen, M.; Virkkunen, P.; Karjalainen-Lindsberg, M.-L.

    2004-01-01

    Different modalities for imaging cancer-bearing breast tissue samples are described and compared. The images include clinical mammograms and computed tomography (CT) images, CT images with partly coherent synchrotron radiation (SR), and CT and radiography images taken with SR using the diffraction enhanced imaging (DEI) method. The images are evaluated by a radiologist and compared with histopathological examination of the samples. Two cases of lobular carcinoma are studied in detail. The indications of cancer are very weak or invisible in the conventional images, but the morphological changes due to invasion of cancer become pronounced in the images taken by the DEI method. The strands penetrating adipose tissue are seen clearly in the DEI-CT images, and the histopathology confirms that some strands contain the so-called 'Indian file' formations of cancer cells. The radiation dose is carefully measured for each of the imaging modalities. The mean glandular dose (MGD) for 50% glandular breast tissue is about 1 mGy in conventional mammography and less than 0.25 mGy in projection DEI, while in the clinical CT imaging the MGD is very high, about 45 mGy. The entrance dose of 95 mGy in DEI-CT imaging gives rise to an MGD of 40 mGy, but the dose may be reduced by an order of magnitude, because the contrast is very large in most images.

  11. ESR dosimetry study for the residents of Kazakhstan exposed to radioactive fallout on 24, August 1956

    Energy Technology Data Exchange (ETDEWEB)

    Zhumadilov, K., E-mail: kassym@hiroshima-u.ac.jp [Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8553 (Japan); Ivannikov, A. [Medical Radiological Research Center, Obninsk 249036 (Russian Federation); Zharlyganova, D. [Astana Medical University, 51a, Beibitshilik str., Astana 010000 (Kazakhstan); Zhumadilov, Zh. [Nazarbayev University, Life Sciences Center, D. Kunayev str., Astana 010000 (Kazakhstan); Stepanenko, V. [Medical Radiological Research Center, Obninsk 249036 (Russian Federation); Abralina, Sh.; Sadvokasova, L. [Semey State Medical Academy, Semey 071400, Abay str. 103 (Kazakhstan); Zhumadilova, A. [Astana Medical University, 51a, Beibitshilik str., Astana 010000 (Kazakhstan); Toyoda, S. [Department of Applied Physics, Faculty of Science, Okayama University of Science, Okayama 700-0005 (Japan); Endo, S. [Department of Quantum Energy Applications, Graduated School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Okamoto, T. [Department of Molecular Oral Medicine and Maxillofacial Surgery, Division of Frontier Medical Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima 734-8553 (Japan); Hoshi, M. [Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8553 (Japan)

    2011-09-15

    The method of electron spin resonance (ESR) dosimetry has been applied to human tooth enamel in order to obtain individual absorbed doses from the population of settlements within the vicinity of the central axis of the radioactive fallout trace from the contaminating nuclear surface test of 24, August 1956. Most of the settlements (Glubokoe, Tavriya, and Gagarino) are located near Ust-Kamenogorsk city, in Kazakhstan (about 400 km to the east from the epicenter of the explosion at the Semipalatinsk Nuclear Test Site (SNTS)). It was found that the excess doses obtained after the subtraction of natural background radiation ranged up to about 120 mGy for the residents of Ust-Kamenogorsk city, whose tooth enamel was formed before 1956. For the residents of Gagarino, excess doses do not exceed 47 mGy for all ages. For the residents of Tavriya, the maximum of excess dose was determined as 54 mGy and for the residents of Glubokoe, the maximum excess dose was about 83 mGy. For the population of the Shemonaikha settlements (about 70 km from the centerline of the radioactive fallout trace) the highest excess dose is 110 mGy. Also for this study, Znamenka village (about 130 km from the epicenter) was included. The Kokpekty settlement was chosen as a control and not subjected to any radioactive contamination and is located 400 km to the Southeast from SNTS.

  12. Measurement of absorbed dose and proposed radiation exposure level

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Takayuki; Koizumi, Masayuki; Furukawa, Tomo [Tokai Univ., Isehara, Kanagawa (Japan). Hospital

    2003-03-01

    Absorbed dose was measured in clinical X-ray examinations using thermoluminescence dosimeter (TLD). Moreover, we distributed the levels of radiation exposure into 3 classes. The presumed dose of the internal organs, e.g., uterus dose, was computed to depth doses with a surface dose. This information provides a prediction of the influence of radiation, and the examination can be performed with the informed consent of the patient. Moreover, we examined the distribution of the level of absorbed dose. We proposed two kinds of radiation exposure level, one to the fetus in a pregnant woman and a general level of radiation exposure that is not applied to pregnant women. The levels were as follows: 0.5 mGy and 100 mGy were considered the boundaries for fetal radiation exposure in a pregnant woman, and 200 mGy and 3 Gy were considered the boundaries for the general level of radiation exposure (excluding pregnant women). (author)

  13. Small intestine biopsy of children with coeliac disease: Influence of X-ray equipment on radiation dosage

    Energy Technology Data Exchange (ETDEWEB)

    Persliden, J. [Dept. of Radiation Physics, Faculty of Health Sciences, Linkoeping Univ. (Sweden); Pettersson, H.B.L. [Dept. of Radiation Physics, Faculty of Health Sciences, Linkoeping Univ. (Sweden); Stenhammar, L. [Dept. of Paediatrics, Central Hospital, Linkoeping (Sweden); Faelth-Magnusson, K. [Dept. of Paediatrics, Faculty of Health Sciences, Linkoeping Univ. (Sweden)

    1994-10-01

    In paediatric radiology intestinal biopsies for the diagnosis of coeliac disease are performed using fluoroscopy. The radiation exposure to the child depends on the X-ray equipment. We report patient measurements from three different equipments (A, B and C) together with a phantom study simulating children of different thicknesses relative to age. The median values of the mean absorbed dose to the child in the irradiated volume were 1.2 mGy (A), 0.79 mGy (B) and 0.15 mGy (C). The results show that the increase in tube potential with increasing distance in one equipment decreases the dosage, and also that modern equipment should be employed. Particularly old image intensifiers should not be used. With an optimal choice of equipment the dosage to the child can be reduced fourfold. The combination of an optimal technique of sedation and an experienced operator can reduce the dosage tenfold. (orig.)

  14. Dosimetry of beta particles using Li:Mg, Cu, P + Ptfe; Dosimetria de particulas beta usando Li: Mg, Cu, P + Ptfe

    Energy Technology Data Exchange (ETDEWEB)

    Olvera, L.; Azorin, J.; Rivera, T. [Depto. de Fisica, UAM-I, 09340 Mexico D.F. (Mexico)

    2003-07-01

    This paper presents the experimental results of determining the thermoluminescence (Tl) response of LiF: Mg, Cu, P + Ptfe pellets excited with {sup 90}Sr/{sup 90}Y beta radiation. The glow curve exhibited three peaks which appear at 121 C, 178 C and 217 C . Its relative sensitivity is 49 with respect to that of the TLD-100 dosemeter taken as a reference. The minimal dose that could be measured was 750 mGy. The Tl response as a function of dose was linear in the range of 0.7 mGy to 22.5 mGy. The study of the repeatability of the information contained in the pellets showed a standard deviation of 2 %. (Author)

  15. Effect of gamma irradiation on the mechanical behavior, thermal properties and structure of epoxy/glass-fiber composite

    Science.gov (United States)

    Wu, Z. X.; Li, J. W.; Huang, C. J.; Huang, R. J.; Li, L. F.

    2013-10-01

    Effect of gamma irradiation on the mechanical, thermal properties and structure of glass fiber reinforced epoxy composites was investigated. The interlaminar shear strength (ILSS) at 77 K and the fracture morphology of the composites were evaluated as a function of radiation dose. In addition, the molecular structure and the thermal stability of epoxy matrix were investigated by means of UV-Vis spectra, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA). It is found that the ILSS at 77 K was affected scarcely up to 5 MGy but decreased significantly after 10 MGy irradiation. The thermal properties of the resin decreased with the increasing irradiation dose. These results can be interpreted by the crosslinking and degradation of the epoxy matrix. The composite appears to be resistant to a dose of 5.0 MGy.

  16. Three-dimensional non-linear magnetohydrodynamic modeling of massive gas injection triggered disruptions in JET

    Science.gov (United States)

    Fil, A.; Nardon, E.; Hoelzl, M.; Huijsmans, G. T. A.; Orain, F.; Becoulet, M.; Beyer, P.; Dif-Pradalier, G.; Guirlet, R.; Koslowski, H. R.; Lehnen, M.; Morales, J.; Pamela, S.; Passeron, C.; Reux, C.; Saint-Laurent, F.

    2015-06-01

    JOREK 3D non-linear MHD simulations of a D2 Massive Gas Injection (MGI) triggered disruption in JET are presented and compared in detail to experimental data. The MGI creates an overdensity that rapidly expands in the direction parallel to the magnetic field. It also causes the growth of magnetic islands ( m / n = 2 / 1 and 3/2 mainly) and seeds the 1/1 internal kink mode. O-points of all island chains (including 1/1) are located in front of the MGI, consistently with experimental observations. A burst of MHD activity and a peak in plasma current take place at the same time as in the experiment. However, the magnitude of these two effects is much smaller than in the experiment. The simulated radiation is also much below the experimental level. As a consequence, the thermal quench is not fully reproduced. Directions for progress are identified. Radiation from impurities is a good candidate.

  17. On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

    Science.gov (United States)

    Nardon, E.; Fil, A.; Chauveau, P.; Tamain, P.; Guirlet, R.; Koslowski, H. R.; Lehnen, M.; Reux, C.; Saint-Laurent, F.; Contributors, JET

    2017-01-01

    A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013).

  18. Morphological Investigation of Foamed Aluminum Parts Produced by Melt Gas Injection

    Directory of Open Access Journals (Sweden)

    R. Surace

    2009-01-01

    Full Text Available Porous metal materials are a new class of materials with low densities, large specific surface, and novel physical and mechanical properties. Their applications are extremely varied: for light weight structural components, for filters and electrodes, and for shock or sound absorbing products. Recently, interesting foaming technology developments have proposed metallic foams as a valid commercial chance; foam manufacturing techniques include solid, liquid, or vapor state methods. The foams presented in this study are produced by Melt Gas Injection (MGI process starting from melt aluminum. The aim of this investigation is to obtain complex foamed aluminum parts in order to make the MGI more flexible. This new method, called MGI-mould process, makes possible to produce 3D-shaped parts with complicated shape or configuration using some moulds obtained by traditional investment casting process.

  19. Radiation-induced micrencephaly in guinea pigs

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, L.K.; Johnston, D.A.; Felleman, D.J.

    1992-01-01

    The effect of x rays on brain weight of guinea pig pups at birth was studied for 21-day old embroys exposed in utero to doses of 75 and 100 mGy. When compared to controls and when corrected for body weight, gestation time, litter size, sex, and examiner differences the brains of irradiated pups weighed approximately 46 mg less than those of controls (p<0.001) for the 75-mGy group and about 55 mg less for the 100-mGy group. Brains of females weighed 51 mg less than those of males of the same body weight. Dam weight and caging conditions had no observed effect on brain weight.

  20. Radiation-induced micrencephaly in guinea pigs

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, L.K.; Johnston, D.A.; Felleman, D.J.

    1992-11-01

    The effect of x rays on brain weight of guinea pig pups at birth was studied for 21-day old embroys exposed in utero to doses of 75 and 100 mGy. When compared to controls and when corrected for body weight, gestation time, litter size, sex, and examiner differences the brains of irradiated pups weighed approximately 46 mg less than those of controls (p<0.001) for the 75-mGy group and about 55 mg less for the 100-mGy group. Brains of females weighed 51 mg less than those of males of the same body weight. Dam weight and caging conditions had no observed effect on brain weight.

  1. Photon and fast neutron dosimetry using aluminium oxide thermoluminescence dosemeters.

    Science.gov (United States)

    Santos, J P; Fernandes, A C; Gonçalves, I C; Marques, J G; Carvalho, A F; Santos, L; Cardoso, J; Osvay, M

    2006-01-01

    Al(2)O(3):Mg,Y thermoluminescence (TL) dosemeters were used to measure photon and fast neutron doses in a fast neutron beam recently implemented at the Portuguese Research Reactor, Nuclear and Technological Institute, Portugal. The activation of Al(2)O(3):Mg,Y by fast neutrons provides information about the fast neutron component by measuring the activity of the reaction products and the self-induced TL signal. Additionally, the first TL reading after irradiation determines the photon dose. The elemental composition of the dosemeters was determined by instrumental neutron activation analysis and by particle induced X-ray emission. Results demonstrate that Al(2)O(3):Mg,Y is an adequate material to discriminate photon and fast neutron fields for reactor dosimetry purposes.

  2. Intestinal biospy in children with coeliac disease; a Swedish national study of radiation dose and risk

    Energy Technology Data Exchange (ETDEWEB)

    Persliden, J.; Pettersson, H.B.L. [Linkoeping Univ. (Sweden). Dept. of Radiation Physics; Faelth-Magnusson, K. [University of Linkoeping (Sweden). Faculty of Health Sciences

    1995-12-31

    In paediatric patients, fluoroscopy is used to monitor intestinal biopsies obtained for the diagnosis of coeliac disease. The radiation dose to the child is dependent on the equipment, the sedation of the patient and the experience of the operator. This study presents patient measurements from a national study in Sweden. The cancer excess lifetime mortality risk (CELMR) and the loss of life expectancy (LLE) are calculated for this patient group. TLD measurements were performed by dosemeters at 40 Swedish paediatric departments performing these biopsies. Information was received on sedation techniques, equipment used and fluoroscopy duration. An exponential curve fit was applied to the entrance and exit dose values and this dose distribution was integrated to get the integral dose. From this the mean absorbed dose in the irradiated volume was calculated. The mean and the median of the mean absorbed dose in the irradiated volume to the children was found to be 1.3 mGy (range 0.05-17.5 mGy) and 0.56 mGy respectively. The mean value of the entrance surface dose was 3.0 mGy (range 0.10-27.1 mGy) and the median was 1.4 mGy. The annual collective dose was calculated to 3.3 man Gy, based on 2500 biopsies per year. Variation in doses was found to depend on, e.g. the age of the equipment, focus to patient distance, sedation and operator experience. With this knowledge of doses received by the children in the diagnosis of coeliac disease, CELMR was found to be 0.5 per 25000 biopsies and LLE was 18 years. Recommendations are given on the proper choice of equipment for the reduction of fluoroscopy doses in pediatric radiology. (Author).

  3. Performance degradation of ferrofluidic feedthroughs in a mixed irradiation field

    Science.gov (United States)

    Simos, Nikolaos; Fernandes, S.; Mittig, Wolfgang; Pellemoine, Frederique; Avilov, M.; Kostin, M.; Mausner, L.; Ronningen, R.; Schein, M.; Bollen, G.

    2017-01-01

    Ferrofluidic feedthrough (FF) rotary seals containing either NdFeB or SmCo-type permanent magnets have been considered for use in the target and beam dump systems of the Facility for Rare Isotope Beams (FRIB). To evaluate their performance under irradiation three FF seals were irradiated in a mixed field consisting of fast neutrons, protons and γ-rays to an average absorbed dose of 0.2, 2.0, and 20.0 MGy at the Brookhaven Linac Isotope Producer facility (BLIP). The radiation types and energy profiles mimic those expected at the FRIB facility. Degradation of the operational performance of these devices due to irradiation is expected to be the result of the de-magnetization of the permanent magnets contained within the seal and the changes in the ferrofluid properties. Post-irradiation performance was evaluated by determining the ferrofluidic seal vacuum tightness and torque under static and dynamic conditions. The study revealed that the ferrofluidic feedthrough seal irradiated to a dose of 0.2 MGy maintained its vacuum tightness under both static and rotational condition while the one irradiated to a dose of 2.0 MGy exhibited signs of ferrofluid damage but no overall performance loss. At 20 MGy dose the effects of irradiation on the ferrofluid properties (viscosity and particle agglomeration) were shown to be severe. Furthermore, limited de-magnetization of the annular shaped Nd2Fe14B and Sm2Co17 magnets located within the irradiated FFs was observed for doses of 0.2 MGy and 20 MGy respectively.

  4. SU-F-I-36: In-Utero Dose Measurements Within Postmortem Subjects for Estimating Fetal Doses in Pregnant Patients Examined with Pulmonary Embolism, Trauma, and Appendicitis CT

    Energy Technology Data Exchange (ETDEWEB)

    Lipnharski, I; Quails, N; Carranza, C; Correa, N; Bidari, S; Bickelhaup, M; Rill, L; Arreola, M [University of Florida, Gainesville, FL (United States)

    2016-06-15

    Purpose: The imaging of pregnant patients is medically necessary in certain clinical situations. The purpose of this work was to directly measure uterine doses in a cadaver scanned with CT protocols commonly performed on pregnant patients in order to estimate fetal dose and assess potential risk. Method: One postmortem subject was scanned on a 320-slice CT scanner with standard pulmonary embolism, trauma, and appendicitis protocols. All protocols were performed with the scan parameters and ranges currently used in clinical practice. Exams were performed both with and without iterative reconstruction to highlight the dose savings potential. Optically stimulated luminescent dosimeters (OSLDs) were inserted into the uterus in order to approximate fetal doses. Results: In the pulmonary embolism CT protocol, the uterus is outside of the primary beam, and the dose to the uterus was under 1 mGy. In the trauma and appendicitis protocols, the uterus is in the primary beam, the fetal dose estimates were 30.5 mGy for the trauma protocol, and 20.6 mGy for the appendicitis protocol. Iterative reconstruction reduced fetal doses by 30%, with uterine doses at 21.3 for the trauma and 14.3 mGy for the appendicitis protocol. Conclusion: Fetal doses were under 1 mGy when exposed to scatter radiation, and under 50 mGy when exposed to primary radiation with the trauma and appendicitis protocols. Consistent with the National Council on Radiation Protection & Measurements (NCRP) and the International Commission on Radiological Protection (ICRP), these doses exhibit a negligible risk to the fetus, with only a small increased risk of cancer. Still, CT scans are not recommended during pregnancy unless the benefits of the exam clearly outweigh the potential risk. Furthermore, when possible, pregnant patients should be examined on CT scanners equipped with iterative reconstruction in order to keep patient doses as low as reasonable achievable.

  5. Neuro-immune response and sleep studies after whole body irradiation with high-LET particles

    Energy Technology Data Exchange (ETDEWEB)

    Marquette, C.; Bertho, J.M.; Wysoki, J.; Maubert, C.; Gerbin, R.; Aigueperse, J. [IRSN, F-92260 Fontenay Aux Roses, (France); Mathieu, J.; Galonnier, M.; Clarencon, D. [CRSSA, Dept Radiobiol and Radiopathol, F-38700 La Tronche, (France); Balanzat, E. [CEA, DSM, CIRIL, Ganil, Caen, (France)

    2009-07-01

    In order to investigate the biological effects of galactic rays on astronaut cerebral functions after space flight, mice were exposed to different heavy ions (HZE) in whole-body conditions at doses comparable to the galactic flux: {sup 12}C, {sup 16}O and {sup 20}Ne (95 MeV/u, at 42-76 mGy). Animals were also exposed to 42 mGy of {sup 60}Co radiation for comparison with HZE. The neuro-immune response, evaluated by interleukin-I (IL-1) measurement, showed that this cytokine was produced 3 h after irradiation by {sup 16}O or {sup 60}Co. In contrast, neither {sup 12}C (56.7 mGy) nor {sup 20}Ne (76 mGy) induced IL-1 production. However, immunohistochemical staining of {sup 12}C-irradiated mouse brain tissue showed 2 months later a marked inflammatory reaction in the hippocampus and a diffuse response in parenchyma. Sleep studies were realized before and after exposure to 42 mGy of {sup 16}O and 76 mGy of {sup 20}Ne: only the {sup 20}Ne radiation displayed a small effect. A slight decrease in paradoxical sleep, corresponding to a reduction in the number of episodes of paradoxical sleep, was manifested between 8 and 22 days after exposure. Exposure to {sup 12}C and {sup 16}O induced no changes either in cellularity of spleen or thymus, or in caspase 3 activity (as much as four months after irradiation). Taken together, these data indicate that the CNS could be sensitive to heavy ions and that responses to HZE impact depend on the nature of the particle, the dose threshold and the time delay to develop biological processes. Differences in responses to different HZE highlight the complex biological phenomena to which astronauts are submitted during space flight. (authors)

  6. Low doses of radiation reduce risks in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Mitchel, R.E.J. [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)

    2004-05-01

    The 'Linear No Threshold' hypothesis, used in all radiation protection practices, assumes that all doses, no matter how low, increase risk. The protective effects of adaptive responses to radiation, shown to exist in lower organisms and in human and other mammalian cells, are inconsistent with this hypothesis. An in vivo test of the hypothesis in mice showed that a 100-mGy dose of {gamma}-radiation protected the mice by increasing latency for acute myeloid leukemia initiated by a subsequent large dose. A similar result was observed in cancer prone mice, where a 10-mGy adapting exposure prior to a large acute dose increased latency for lymphomas without altering frequency. Increasing the adapting dose to 100-mGy eliminated the protective effect. In the cancer prone mice, a 10-mGy dose alone, without a subsequent high dose, increased latency for spontaneous osteosarcomas and lymphomas without altering frequency. Increasing the dose to 100-mGy decreased latency for spontaneous osteosarcomas but still increased latency for lymphomas, indicating that this higher dose was in a transition zone between reduced and increased risk, and that the transition dose from protective to detrimental effects is tumor type specific. In genetically normal fetal mice, prior low doses also protected against radiation induced teratogenic effects. In genetically normal adult male mice, high doses induce mutations in sperm stem cells, detectable as heritable mutations in the offspring of these mice. A prior 100 mGy dose protected the male mice from induction of these heritable mutations by the large dose. We conclude that adaptive responses are induced by low doses in normal or cancer prone mice, and that these responses can reduce the risk of cancer, teratogenesis and heritable mutations. At low doses in vivo, the relationship between dose and risk is not linear, and low doses can reduce risk. (author)

  7. Survey of pediatric MDCT radiation dose from university hospitals in Thailand. A preliminary for national dose survey

    Energy Technology Data Exchange (ETDEWEB)

    Kritsaneepaiboon, Supika [Dept. of Radiology, Faculty of Medicine, Prince of Songkla Univ., Hat Yai (Thailand)], e-mail: supikak@yahoo.com; Trinavarat, Panruethai [Dept. of Radiology, Faculty of Medicine, Chulalongkorn Univ., Bangkok (Thailand); Visrutaratna, Pannee [Dept. of Radiology, Faculty of Medicine, Chiang Mai Univ., Chiang Mai (Thailand)

    2012-09-15

    Background: Increasing pediatric CT usage worldwide needs the optimization of CT protocol examination. Although there are previous published dose reference level (DRL) values, the local DRLs should be established to guide for clinical practice and monitor the CT radiation. Purpose: To determine the multidetector CT (MDCT) radiation dose in children in three university hospitals in Thailand in four age groups using the CT dose index (CTDI) and dose length product (DLP). Material and Methods: A retrospective review of CT dosimetry in pediatric patients (<15 years of age) who had undergone head, chest, and abdominal MDCT in three major university hospitals in Thailand was performed. Volume CTDI (CTDIvol) and DLP were recorded, categorized into four age groups: <1 year, 1- < 5 years, 5- <10 years, and 10- <15 years in each scanner. Range, mean, and third quartile values were compared with the national reference dose levels for CT in pediatric patients from the UK and Switzerland according to International Commission on Radiological Protection (ICRP) recommendation. Results: Per age group, the third quartile values for brain, chest, and abdominal CTs were, respectively, in terms of CTDIvol: 25, 30, 40, and 45 mGy; 4.5, 5.7, 10, and 15.6 mGy; 8.5, 9, 14, and 17 mGy; and in terms of DLP: 400, 570, 610, and 800 mGy cm; 80, 140, 305, and 470 mGy cm; and 190, 275, 560,765 mGy cm. Conclusion: This preliminary national dose survey for pediatric CT in Thailand found that the majority of CTDIvol and DLP values in brain, chest, and abdominal CTs were still below the diagnostic reference levels (DRLs) from the UK and Switzerland regarding to ICRP recommendation.

  8. The Effects of Electron Radiation on the Glass Transition Temperature of a Polyetherimide.

    Science.gov (United States)

    Kern, Kristen Tulloch

    The effects of electron radiation on a polyetherimide (PEI), Ultem^{cdot}, were investigated. In particular, the changes in the glass transition temperature (T_{g} ) with absorbed radiation dose were studied. The polymer was exposed to mono-energetic beams of 100-keV electrons and 1.0-MeV electrons for doses up to 100 megagray (MGy). Dosimetry for the exposures was based on Monte -Carlo simulations of the transfer of energy from an energetic electron to the polymer and on comparison to Nylon standards. Dynamic mechanical analysis was used to determine the T _{g} for non-exposed PEI and the changes in T_{g} resulting from irradiation. The T_{g} did not change significantly for doses up to and including 75 MGy, while a significant increase in T_ {g} occurred for a dose of 100 MGy. The cross-link and chain scission densities in the irradiated PEI were determined using infrared spectroscopy. The cross -link density increased with dose for all doses investigated. The chain scission density increased with dose for doses up to 75 MGy, but was lower for a dose of 100 MGy than for a dose of 75 MGy. Radical population kinetics, based in part on data from an electron paramagnetic resonance study, were correlated with the cross-link density and chain scission density to investigate the mechanism for the observed density variations with dose. The radical population simulations suggest that chain scissioning occurs less readily when the average radical separation during the exposure is less than three molecular radii. Finally, a model for the combined effects of cross-linking and chain scissioning is proposed which combines a statistical-mechanical model for the change in T_{g} with cross-link density and a free-volume model for the change in T _{g} with chain scission density.

  9. Line profiles of the two-phase medium broad-line region in active galactic nuclei

    Institute of Scientific and Technical Information of China (English)

    薛随建; 林宣滨; 程福臻; John Kwan

    1996-01-01

    In the framework of BLR in AGNs, i.e. large number of small, cold and dense emission-line clouds immerging in an intercloud hot medium, a delicate radiation model for a typical emission cloud is established, in which the backside photoionization of the cloud against the central continuum source by the scattered diffuse continuum in the hot medium is considered. Under the assumption of the radial kinematics of the BLR clouds, the line profiles for the two important UV emission-lines, Lya and CIV/11549 are computed; and based on these calculations, various physical factors that affect the properties of the emission-line profiles are discussed. It is concluded that: (i) when the BLR clouds is inflow, there exists a confining hot medium with density around 2 x 105 cm-3. In this case, theoretical line profiles agree well with the observational; (ii) both symmetric Lya and nearly symmetric CIV line profiles show blue velocity shifts, the quantities of which are sensitive to the cutoff of the outer radius of t

  10. Riemann Zeta Zeros and Prime Number Spectra in Quantum Field Theory

    Science.gov (United States)

    Menezes, G.; Svaiter, B. F.; Svaiter, N. F.

    2013-10-01

    The Riemann hypothesis states that all nontrivial zeros of the zeta function lie in the critical line Re(s) = 1/2. Hilbert and Pólya suggested that one possible way to prove the Riemann hypothesis is to interpret the nontrivial zeros in the light of spectral theory. Using the construction of the so-called super-zeta functions or secondary zeta functions built over the Riemann nontrivial zeros and the regularity property of one of this function at the origin, we show that it is possible to extend the Hilbert-Pólya conjecture to systems with countably infinite number of degrees of freedom. The sequence of the nontrivial zeros of the Riemann zeta function can be interpreted as the spectrum of a self-adjoint operator of some hypothetical system described by the functional approach to quantum field theory. However, if one considers the same situation with numerical sequences whose asymptotic distributions are not "far away" from the asymptotic distribution of prime numbers, the associated functional integral cannot be constructed. Finally, we discuss possible relations between the asymptotic behavior of a sequence and the analytic domain of the associated zeta function.

  11. HST Discovery of a z = 3.9 Multiply Imaged Galaxy Behind the Complex Cluster Lens WARPS J1415.1+36 at z = 1.026

    CERN Document Server

    Huang, X; Fakhouri, H K; Aldering, G; Amanullah, R; Barbary, K; Brodwin, M; Connolly, N V; Dawson, K S; Doi, M; Faccioli, L; Fadeev, V; Fruchter, A S; Goldhaber, G; Gladders, M D; Hennawi, J F; Ihara, Y; Jee, M J; Kowalski, M; Konishi, K; Lidman, C; Meyers, J; Moustakas, L A; Perlmutter, S; Rubin, D; Schlegel, D J; Spadafora, A L; Suzuki, N; Takanashi, N; Yasuda, N

    2009-01-01

    We report the discovery of a multiply lensed Ly Alpha (Lya) emitter at z = 3.90 behind the massive galaxy cluster WARPS J1415.1+3612 at z = 1.026. Images taken by the Hubble Space Telescope(HST) using ACS reveal a complex lensing system that produces a prominent, highly magnified arc and a triplet of smaller arcs grouped tightly around a spectroscopically confirmed cluster member. Spectroscopic observations using FOCAS on Subaru confirm strong Lya emission in the source galaxy and provide redshifts for more than 21 cluster members, from which we obtain a velocity dispersion of 807+/-185 km/s. Assuming a singular isothermal sphere profile, the mass within the Einstein ring (7.13+/-0.38") corresponds to a central velocity dispersion of 686+15-19 km/s for the cluster, consistent with the value estimated from cluster member redshifts. Our mass profile estimate from combining strong lensing and dynamical analyses is in good agreement with both X-ray and weak lensing results.

  12. The MUSE 3D view of the Hubble Deep Field South

    CERN Document Server

    Bacon, R; Richard, J; Contini, T; Drake, A; Franx, M; Tacchella, S; Vernet, J; Wisotzki, L; Blaizot, J; Bouché, N; Bouwens, R; Cantalupo, S; Carollo, C M; Carton, D; Caruana, J; Clément, B; Dreizler, S; Epinat, B; Guiderdoni, B; Herenz, C; Husser, T -O; Kamann, S; Kerutt, J; Kollatschny, W; Krajnovic, D; Lilly, S; Martinsson, T; Michel-Dansac, L; Patricio, V; Schaye, J; Shirazi, M; Soto, K; Soucail, G; Steinmetz, M; Urrutia, T; Weilbacher, P; de Zeeuw, T

    2014-01-01

    We observed the Hubble Deep Field South with the new panoramic integral field spectrograph MUSE that we built and just commissioned at the VLT. The data cube resulting from 27 hours of integration covers one arcmin^2 field of view at an unprecedented depth with a 1 sigma emission line surface brightness limit of 1x$10^{-19}$ erg/s/cm$^2$/arcsec$^2$ and contains ~90,000 spectra. We present the combined and calibrated data cube, and we perform a first-pass analysis of the sources detected in the HDF-S imaging. We measured the redshifts of 189 sources up to a magnitude F814W = 29.5, increasing by more than an order of magnitude the number of known spectroscopic redshifts in this field. We also discovered 26 Lya emitting galaxies which are not detected in the HST WFPC2 deep broad band images. The intermediate spectral resolution of 2.3{\\AA} allows us to separate resolved asymmetric Lya emitters, [O II] emitters, and C III] emitters and the large instantaneous wavelength range of 4500{\\AA} helps to identify single...

  13. Intergalactic Baryons in the Local Universe

    CERN Document Server

    Danforth, Charles W

    2008-01-01

    Simulations predict that shocks from large-scale structure formation and galactic winds have reduced the fraction of baryons in the warm, photoionized phase (the Lya forest) from nearly 100% in the early universe to less than 50% today. Some of the remaining baryons are predicted to lie in the warm-hot ionized medium (WHIM) phase at T=10^5-10^7 K, but the quantity remains a highly tunable parameter of the models. Modern UV spectrographs have provided unprecedented access to both the Lya forest and potential WHIM tracers at z~0, and several independent groups have constructed large catalogs of far-UV IGM absorbers along ~30 AGN sight lines. There is general agreement between the surveys that the warm, photoionized phase makes up ~30% of the baryon budget at z~0. Another ~10% can be accounted for in collapsed structures (stars, galaxies, etc.). However, interpretation of the ~100 high-ion (OVI, etc) absorbers at z<0.5 is more controversial. These species are readily created in the shocks expected to exist in...

  14. The UV-Optical Albedo of Broad Emission Line Clouds

    CERN Document Server

    Korista, K T; Korista, Kirk; Ferland, Gary

    1997-01-01

    We explore the effective UV-optical albedos of a variety of types of broad emission line clouds, as well as their possible effects on the observed spectra of AGN. An important albedo source in moderately ionized ionization-bounded clouds is that due to neutral hydrogen: Rayleigh scattering of continuum photons off the extreme damping wings of Lya. The photons resulting from this scattering mechanism may contribute significantly to the Lya emission line, especially in the very broad wings. In addition, line photons emitted near 1200 Angstroms (e.g., N V 1240) that stream toward the neutral portion of the cloud may be reflected off this Rayleigh scattering mirror, so that they preferentially escape from the illuminated face. Inclusion of this effect can alter predicted emission line strengths and profiles. In more highly-ionized ionization-bounded clouds, Thompson scattering dominates the UV-optical albedo, but this albedo is lessened by the hydrogen gas opacity. These clouds are most reflective on the long wav...

  15. The First Systematic Survey for Lyman Alpha Emitters at z=7.3 with Red-sensitive Subaru/Suprime-Cam

    CERN Document Server

    Shibuya, Takatoshi; Ota, Kazuaki; Iye, Masanori; Ouchi, Masami; Furusawa, Hisanori; Shimasaku, Kazuhiro; Hattori, Takashi

    2011-01-01

    We have performed deep imaging surveys for Lyman Alpha emitters (LAEs) at redshift ~ 7.3 in two blank fields, the Subaru Deep Field (SDF) and the Subaru/XMM-Newton Deep Field (SXDF), using the Subaru/Suprime-Cam equipped with new red-sensitive CCDs and a new narrow-band filter, NB1006 (lambda_c=10,052A, FWHM=214A). By comparing the NB1006 magnitudes of detected objects with those at other shorter wavelength bands, we identified four objects as LAE candidates that exhibit luminosity excess in NB1006. By carrying out deep follow-up spectroscopy for three of them using Subaru/FOCAS and Keck/DEIMOS, a definitively asymmetric emission line is detected for one of them, SXDF-NB1006-2. Assuming this line is LyA, this object is a LAE at z=7.215 which has luminosity of 1.2^{+1.5}_{-0.6} x 10^{43} erg s-1, star formation rate (SFR) of 11 Mo yr-1 estimated from the LyA emission line, and a weighted skewness S_w = 4.90+-0.86. Another object, SDF-NB1006-2, shows variable photometry and is thus probably a quasar (QSO) or an...

  16. The visibility of Lyman Alpha Emitters: constraining reionization, ionizing photons and dust

    CERN Document Server

    Hutter, A; Partl, A M; Müller, V

    2014-01-01

    We couple state of the art cosmological simulations (GADGET-2) with a dust model and a radiative transfer code (pCRASH) to build a complete model for high-redshift Lyman Alpha emitters (LAEs). Due to poor constraints available on the escape fraction of HI ionizing photons (f_esc) from galaxies, we use five different values f_esc=0.05,0.25,0.5,0.75,0.95 to post-process the cosmological simulation with pCRASH. Starting from a completely neutral Universe, we run pCRASH until reionization is complete, i.e. the average neutral hydrogen (HI) fraction drops to ~ 10^-4. For a given f_esc and combination, the only free-parameter left to match model results to observations is the relative escape of Lyman Alpha (Lya) and continuum photons from the galactic environment (f_\\alpha/f_c). Starting from a scenario wherein dust is homogeneously distributed (f_\\alpha/f_c ~ 0.68), we find that the observed LAE UV and Lya luminosity functions (LFs) jointly constrain f_esc ~ 0.05 and and f_\\alpha/f_c such that a decrease in th...

  17. HI content, metallicities and spin temperatures of damped and sub-damped Lyman alpha systems in the redshift desert (0.6 < z < 1.7)

    CERN Document Server

    Ellison, Sara L; Prochaska, J Xavier; Momjian, Emmanuel; Worseck, Gabor

    2012-01-01

    The HI 21cm absorption optical depth and the N(HI) derived from Lya absorption can be combined to yield the spin temperature (Ts) of DLAs. Although Ts measurements exist for samples of DLAs with z 1.7, the intermediate redshift regime currently contains only 2 HI 21cm detections, leading to a `redshift desert' that spans 4 Gyrs of cosmic time. To connect the low and high z regimes, we present observations of the Lya line of six 0.6

  18. Probing Quasar Winds Using Intrinsic Narrow Absorption Lines

    Science.gov (United States)

    Culliton, Christopher S.; Charlton, Jane C.; Eracleous, Michael; Roberts, Amber; Ganguly, Rajib; Misawa, Toru; Muzahid, Sowgat

    2017-01-01

    Quasar outflows are important for understanding the accretion and growth processes of the central black hole. Furthermore, outflows potentially have a role in providing feedback to the galaxy, and halting star formation and infall of gas. The geometry and density of these outflows remain unknown, especially as a function of ionization and velocity. Having searched ultraviolet spectra at both high redshift (VLT/UVES; 1.4physically associated with) the quasar. We identify intrinsic NALs with a wide range of properties, including ejection velocity, coverage fraction, and ionization level. We also consider the incidence of intrinsic absorbers as a function of quasar properties (optical, radio and X-ray fluxes), and find that radio properties and quasar orientation are influential in determining if a quasar is likely to host an intrinsic system. We find that there is a continuum of properties within the intrinsic NAL sample, rather than discrete families, ranging from partially covered CIV systems with black Lya and with a separate low ionization gas phase to partially covered NV systems with partially covered Lya and without detected low ionization gas. Additionally, we construct a model describing the spatial distributions, geometries, and varied ionization structures of intrinsic NALs.

  19. The ESO UVES Advanced Data Products Quasar Sample - I. Dataset and New N_HI Measurements of Damped Absorbers

    CERN Document Server

    Zafar, Tayyaba; Peroux, Celine

    2013-01-01

    We present here a dataset of quasars observed with the Ultraviolet Visual Echelle Spectrograph (UVES) on the VLT and available in the ESO UVES Advanced Data Products archive. The sample is made up of a total of 250 high resolution quasar spectra with emission redshifts ranging from 0.191 10^{19} cm^{-2}, which constitutes the sub-damped Lya absorber (sub-DLA) threshold. Within the wavelength coverage of our UVES data, we find 150 damped Lya systems (DLAs)/sub-DLAs in the range 1.5 < z_abs < 4.7. Of these 150, 93 are DLAs and 57 are sub-DLAs. An extensive search in the literature indicates that 6 of these DLAs and 13 of these sub-DLAs have their N_HI measured for the first time. Among them, 10 are new identifications as DLAs/sub-DLAs. For each of these systems, we obtain an accurate measurement of the HI column density and the absorber's redshift in the range 1.7 < z_abs < 4.2 by implementing a Voigt profile-fitting algorithm. These absorbers are further confirmed thanks to the detection of associ...

  20. 3-cm Fine Structure Masers: A Unique Signature of Supermassive Black Hole Formation via Direct Collapse in the Early Universe

    CERN Document Server

    Dijkstra, Mark; Loeb, Abraham

    2016-01-01

    The direct collapse black hole (DCBH) scenario describes the isothermal collapse of a pristine gas cloud directly into a massive, M_BH=10^4-10^6 M_sun black hole. In this paper we show that large HI column densities of primordial gas at T~10^4 K with low molecular abundance - which represent key aspects of the DCBH scenario - provide optimal conditions for pumping of the 2p-level of atomic hydrogen by trapped Lyman alpha (Lya) photons. This Lya pumping mechanism gives rise to inverted level population of the 2s_1/2-2p_3/2 transition, and therefore to stimulated fine structure emission at 3.04 cm (rest-frame). We show that simplified models of the DCBH scenario amplify the CMB by up to a factor of 10^5, above which the maser saturates. Hyperfine splitting of the 3-cm transition gives rise to a characteristic broad (FWHM ~ tens of MHz in the observers frame) asymmetric line profile. This signal subtends an angular scale of ~ 1-10 mas, which translates to a flux of ~ 0.3-3 microJy, which is detectable with ultra...

  1. Lyman-alpha forest-CMB cross-correlation and the search for the ionized baryons at high redshift

    CERN Document Server

    Croft, R A C; Hernquist, L; Croft, Rupert A.C.; Hernquist, Lars

    2005-01-01

    The intergalactic neutral hydrogen which is responsible for the Lyman alpha forest of quasar absorption is a tracer of much larger amounts of ionised hydrogen. The ionised component has yet to be detected directly, but is expected to scatter CMB photons via the Sunyaev-Zel'dovich (SZ) effect. We use hydrodynamic simulations of a LambdaCDM universe to create mock quasar spectra and CMB sky maps. We find that the high-z Lya forest gas causes temperature fluctuations of the order of 1 muK rms in the CMB on arcmin scales. The kinetic and thermal SZ effects have a similar magnitude at z=3, with the thermal effect becoming relatively weaker as expected at higher z. The CMB signal associated with lines of sight having HI column densities > 10^18 cm^-2 is only marginally stronger than that for lower column densities. The strong dependence of rms temperature fluctuation on mean Lya absorbed flux, however, suggests that the CMB signal effectively arises in lower density material. We investigate the use of the cross-cor...

  2. Dissecting the Gaseous Halos of z~2 Damped Ly$\\alpha$ Systems with Close Quasar Pairs

    CERN Document Server

    Rubin, Kate H R; Prochaska, J Xavier; Simcoe, Robert A; Myers, Adam; Lau, Marie Wingyee

    2014-01-01

    We use spectroscopy of close pairs of quasars to study diffuse gas in the circumgalactic medium (CGM) surrounding a sample of 40 Damped Lya systems (DLAs). The primary sightline in each quasar pair probes an intervening DLA in the redshift range 1.6 10^17.2 cm^-2) to be greater than ~30% within $R_{\\perp} 0.2 Ang occurs with an incidence f_C (W_1526 > 0.2 Ang) = 20(+12/-8)% within $R_{\\perp} 0.2 Ang) = 57(+12/-13)% within $R_{\\perp} 98% confidence, suggesting that DLAs arise close to the centers of their host halos rather than on their outskirts. Finally, the average Lya, CII and CIV equivalent widths are consistent with those measured around z~2 Lyman Break Galaxies. Assuming that DLAs trace a galaxy population with lower masses and luminosities, this finding implies that the absorption strength of cool circumgalactic material has a weak dependence on dark matter halo mass for M_h < 10^12 M_sun.

  3. The Heavy Element Enrichment of Lyman alpha Clouds in the Virgo Supercluster

    CERN Document Server

    Tripp, T M; Williger, G M; Heap, S R; Bowers, C W; Danks, A C; Davé, R; Green, R F; Gull, T R; Joseph, C L; Kaiser, M E; Lindler, D; Weymann, R J; Woodgate, B E

    2002-01-01

    Using high S/N STIS echelle spectra (FWHM=7 km/s) of 3C 273, we constrain the metallicities of two Lya clouds in the vicinity of the Virgo cluster. We detect C II, Si II, and Si III absorption lines in the Lya absorber at z = 0.00530. Previous observations with FUSE have revealed Ly beta - Ly theta lines at this redshift, thereby accurately constraining N(H I). We model the ionization of the gas and derive [C/H] = -1.2^{+0.3}_{-0.2}, [Si/C] = 0.2+/-0.1, and log n_{H} = -2.8+/-0.3. The model implies a small absorber thickness, ~70 pc, and thermal pressure p/k ~ 40 cm^{-3} K. It is most likely that the absorber is pressure confined by an external medium because gravitational confinement would require a very high ratio of dark matter to baryonic matter. Based on Milky Way sight lines in which carbon and silicon abundances have been reliably measured in the same interstellar cloud (including new measurements presented herein), we argue that the overabundance of Si relative to C is not due to dust depletion. Inste...

  4. CLASH-VLT: spectroscopic confirmation of a z=6.11 quintuply lensed galaxy in the Frontier Fields Cluster RXC J2248.7-4431

    CERN Document Server

    Balestra, I; Rosati, P; Monna, A; Grillo, C; Nonino, M; Mercurio, A; Biviano, A; Bradley, L; Coe, D; Fritz, A; Postman, M; Seitz, S; Scodeggio, M; Zheng, W; Ziegler, B; Zitrin, A; Annunziatella, M; Bartelmann, M; Benitez, N; Broadhurst, T; Bouwens, R; Czoske, O; Donahue, M; Ford, H; Girardi, M; Infante, L; Kelson, D; Koekemoer, A; Kuchner, U; Lemze, D; Lombardi, M; Maier, C; Medezinski, E; Melchior, P; Meneghetti, M; Merten, J; Moustakas, L; Presotto, V; Smit, R; Tozzi, P; Umetsu, K

    2013-01-01

    We present VIsible Multi-Object Spectrograph (VIMOS) observations of a z 6 galaxy quintuply imaged by the Frontier Fields galaxy cluster RXC J2248.7-4431 (z=0.348). This sub-L^*, high-z galaxy has been recently discovered by Monna et al. (2013) using dropout techniques with the 16-band HST photometry acquired as part of the Cluster Lensing And Supernova survey with Hubble (CLASH). Obtained as part of the CLASH-VLT survey, the VIMOS medium-resolution spectra of this source show a very faint continuum between ~8700A and ~9300A and a prominent emission line at 8643A, which can be readily identified with Lyman-alpha at z=6.110. The emission line exhibits an asymmetric profile, with a more pronounced red wing. The rest-frame equivalent width of the line is EW=79+-10A. After correcting for magnification, the star-formation rate (SFR) estimated from the Lya line is SFR(Lya)=11 M_{sol}/yr and that estimated from the UV data is SFR(UV)=3 M$_{sol}/yr. We estimate that the effective radius of the source is R_e6 M$_{sol}...

  5. The Close AGN Reference Survey (CARS) - What is causing Mrk1018's return to the shadows after 30 years?

    CERN Document Server

    Husemann, B; Tremblay, G R; Krumpe, M; Dexter, J; Busch, G; Combes, F; Croom, S M; Davis, T A; Eckart, A; McElroy, R E; Perez-Torres, M; Powell, M; Scharwächter, J

    2016-01-01

    We recently discovered that the active galactic nucleus (AGN) of Mrk 1018 has changed optical type again after 30 years as a type 1 AGN. Here we combine Chandra, NuStar, Swift, Hubble Space Telescope and ground-based observations to explore the cause of this change. The 2-10keV flux declines by a factor of ~8 between 2010 and 2016. We show with our X-ray observation that this is not caused by varying neutral hydrogen absorption along the line-of-sight up to the Compton-thick level. The optical-UV spectral energy distributions are well fit with a standard geometrically thin optically thick accretion disc model that seems to obey the expected $L\\sim T^4$ relation. It confirms that a decline in accretion disc luminosity is the primary origin for the type change. We detect a new narrow-line absorber in Lya blue-shifted by ~700km/s with respect to the systemic velocity of the galaxy. This new Lya absorber could be evidence for the onset of an outflow or a companion black hole with associated gas that could be rela...

  6. Spectroscopic confirmation of two Lyman break galaxies at redshift beyond 7

    CERN Document Server

    Vanzella, E; Fontana, A; Grazian, A; Castellano, M; Boutsia, K; Cristiani, S; Dickinson, M; Gallozzi, S; Giallongo, E; Giavalisco, M; Maiolino, R; Moorwood, A; Paris, D; Santini, P

    2010-01-01

    We report the spectroscopic confirmation of two Lyman break galaxies at redshift > 7. The galaxies were observed as part of an utra-deep spectroscopic campaign with FORS2 at the ESO/VLT for the confirmation of z~7 "z--band dropout'' candidates selected from our VLT/Hawk-I imaging survey. Both galaxies show a prominent emission line at 9735A and 9858A respectively: the lines have fluxes around ~ 1-1.2 x 10^(-17) erg/s/cm2 and exhibit a sharp decline on the blue side and a tail on the red side. The asymmetry is quantitatively comparable to the observed asymmetry in z~6 Lya lines, where absorption by neutral hydrogen in the IGM truncates the blue side of the emission line profile. We carefully evaluate the possibility that the galaxies are instead at lower redshift and we are observing either [OII], [OIII] or Ha emission: however from the spectroscopic and the photometric data we conclude that there are no other plausible identifications, except for Lya at redshift > 7, making these the first robust Lyman break ...

  7. Through Thick and Thin - HI Absorption in Cosmological Simulations

    CERN Document Server

    Altay, Gabriel; Schaye, Joop; Crighton, Neil H M; Vecchia, Claudio Dalla

    2010-01-01

    We investigate the column density distribution function of neutral hydrogen at redshift z = 3 using a cosmological simulation of galaxy formation from the OverWhelmingly Large Simulations (OWLS) project. The base simulation includes gravity, hydrodynamics, star formation, supernovae feedback, stellar winds, chemodynamics, and element-by-element cooling in the presence of a uniform UV background. Self-shielding and formation of molecular hydrogen are treated in post-processing, without introducing any free parameters, using an accurate reverse ray-tracing algorithm and an empirical relation between gas pressure and molecular mass fraction. The simulation reproduces the observed z = 3 abundance of Ly-A forest, Lyman Limit and Damped Ly-A HI absorption systems probed by quasar sight lines over ten orders of magnitude in column density. Self-shielding flattens the column density distribution for NHI > 10^18 cm-2, while the conversion to fully neutral gas and conversion of HI to H2 steepen it around column densiti...

  8. Time-resolved Ultraviolet Spectroscopy of the M-dwarf GJ 876 Exoplanetary System

    CERN Document Server

    France, Kevin; Tian, Feng; Froning, Cynthia S; Roberge, Aki

    2012-01-01

    Extrasolar planets orbiting M-stars may represent our best chance to discover habitable worlds in the coming decade. The ultraviolet spectrum incident upon both Earth-like and Jovian planets is critically important for proper modeling of their atmospheric heating and chemistry. In order to provide more realistic inputs for atmospheric models of planets orbiting low-mass stars, we present new near- and far-ultraviolet (NUV and FUV) spectroscopy of the M-dwarf exoplanet host GJ 876 (M4V). Using the COS and STIS spectrographs aboard the Hubble Space Telescope, we have measured the 1150-3140A spectrum of GJ 876. We have reconstructed the stellar HI LyA emission line profile, and find that the integrated LyA flux is roughly equal to the rest of the integrated flux (1150-1210A + 1220-3140A) in the entire ultraviolet bandpass (F(LyA)/F(FUV+NUV) ~0.7). This ratio is ~ 2500x greater than the solar value. We describe the ultraviolet line spectrum and report surprisingly strong fluorescent emission from hot H2 (T(H2) > ...

  9. The Nature of the Low-redshift Ly-$\\alpha$ Clouds

    CERN Document Server

    Shull, J M

    1997-01-01

    I discuss recent HST observations and interpretation of low-z Ly-alpha clouds toward nearby Seyferts and QSOs, including their frequency, space density, estimated mass, association with galaxies, and contribution to Omega_b. Our HST/GHRS detections of 73 Lya absorbers with N_HI > 10^12.6 cm^(-2) along 11 sightlines covering pathlength Delta(cz) = 86,000 km/s show f(>N_HI) proportional to N_HI^(-0.6 +/- 0.2). A group of strong absorbers toward PKS~2155-304 may be associated with gas (400-800)/h_75 kpc from 4 large galaxies with low metallicity (<0.004 solar) and D/H < 2 x 10^-4. At low-z, we derive a metagalactic ionizing radiation field and Lya-forest baryon density J_0 = (1.1 +/- 0.4) x 10^(-23) ergs/cm^2/s/Hz/sr and Omega_b = (0.008 +/- 0.004) h_75^(-1) [J_-23 N_14 b_100]^0.5 for clouds of characteristic size b = (100 kpc)b_100.

  10. Electromagnetic Radiation Hardness of Diamond Detectors

    CERN Document Server

    Behnke, T; Ghodbane, N; Imhof, A; Martínez, C; Zeuner, W

    2002-01-01

    The behavior of artificially grown CVD diamond films under intense electromagnetic radiation has been studied. The properties of irradiated diamond samples have been investigated using the method of thermally stimulated current and by studying their charge collection properties. Diamonds have been found to remain unaffected after doses of 6.8 MGy of 10 keV photons and 10 MGy of MeV-range photons. This observation makes diamond an attractive detector material for a calorimeter in the very forward region of the proposed TESLA detector.

  11. Assessment of dedicated low-dose cardiac micro-CT reconstruction algorithms using the left ventricular volume of small rodents as a performance measure

    Energy Technology Data Exchange (ETDEWEB)

    Maier, Joscha, E-mail: joscha.maier@dkfz.de [Medical Physics in Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Sawall, Stefan; Kachelrieß, Marc [Medical Physics in Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany and Institute of Medical Physics, University of Erlangen–Nürnberg, 91052 Erlangen (Germany)

    2014-05-15

    Purpose: Phase-correlated microcomputed tomography (micro-CT) imaging plays an important role in the assessment of mouse models of cardiovascular diseases and the determination of functional parameters as the left ventricular volume. As the current gold standard, the phase-correlated Feldkamp reconstruction (PCF), shows poor performance in case of low dose scans, more sophisticated reconstruction algorithms have been proposed to enable low-dose imaging. In this study, the authors focus on the McKinnon-Bates (MKB) algorithm, the low dose phase-correlated (LDPC) reconstruction, and the high-dimensional total variation minimization reconstruction (HDTV) and investigate their potential to accurately determine the left ventricular volume at different dose levels from 50 to 500 mGy. The results were verified in phantom studies of a five-dimensional (5D) mathematical mouse phantom. Methods: Micro-CT data of eight mice, each administered with an x-ray dose of 500 mGy, were acquired, retrospectively gated for cardiac and respiratory motion and reconstructed using PCF, MKB, LDPC, and HDTV. Dose levels down to 50 mGy were simulated by using only a fraction of the projections. Contrast-to-noise ratio (CNR) was evaluated as a measure of image quality. Left ventricular volume was determined using different segmentation algorithms (Otsu, level sets, region growing). Forward projections of the 5D mouse phantom were performed to simulate a micro-CT scan. The simulated data were processed the same way as the real mouse data sets. Results: Compared to the conventional PCF reconstruction, the MKB, LDPC, and HDTV algorithm yield images of increased quality in terms of CNR. While the MKB reconstruction only provides small improvements, a significant increase of the CNR is observed in LDPC and HDTV reconstructions. The phantom studies demonstrate that left ventricular volumes can be determined accurately at 500 mGy. For lower dose levels which were simulated for real mouse data sets, the

  12. Dose levels in conventional X-rays; Niveles de dosis en radiografia convencional

    Energy Technology Data Exchange (ETDEWEB)

    Guerra M, J. A.; Gonzalez G, J. A.; Pinedo S, A.; Salas L, M. A.; Vega C, H. R. [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Rivera M, T. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, IPN, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico); Azorin N, J. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico)], e-mail: rgg_df@hotmail.com

    2009-10-15

    There were a series of measures in the General Hospital of Fresnillo in the X-ray Department in the areas of X-1 and X-2-ray rooms and in the neonatal intensive care unit 2, was determined the dose surface entry in eyes, thyroid and gonads for patients undergoing to X-ray study of chest Tele by thermoluminescent dosimetry. Five dosemeters were used in each one of the scans; so find the following dose ranges 20 +{sub -} 23 mGy to 350 +{sub -} 41 mGy. With the results obtained we can conclude that the procedures used and the equipment calibration is adequate. (Author)

  13. Diagnostic Accuracy of CT Enterography for Active Inflammatory Terminal Ileal Crohn Disease: Comparison of Full-Dose and Half-Dose Images Reconstructed with FBP and Half-Dose Images with SAFIRE.

    Science.gov (United States)

    Gandhi, Namita S; Baker, Mark E; Goenka, Ajit H; Bullen, Jennifer A; Obuchowski, Nancy A; Remer, Erick M; Coppa, Christopher P; Einstein, David; Feldman, Myra K; Kanmaniraja, Devaraju; Purysko, Andrei S; Vahdat, Noushin; Primak, Andrew N; Karim, Wadih; Herts, Brian R

    2016-08-01

    Purpose To compare the diagnostic accuracy and image quality of computed tomographic (CT) enterographic images obtained at half dose and reconstructed with filtered back projection (FBP) and sinogram-affirmed iterative reconstruction (SAFIRE) with those of full-dose CT enterographic images reconstructed with FBP for active inflammatory terminal or neoterminal ileal Crohn disease. Materials and Methods This retrospective study was compliant with HIPAA and approved by the institutional review board. The requirement to obtain informed consent was waived. Ninety subjects (45 with active terminal ileal Crohn disease and 45 without Crohn disease) underwent CT enterography with a dual-source CT unit. The reference standard for confirmation of active Crohn disease was active terminal ileal Crohn disease based on ileocolonoscopy or established Crohn disease and imaging features of active terminal ileal Crohn disease. Data from both tubes were reconstructed with FBP (100% exposure); data from the primary tube (50% exposure) were reconstructed with FBP and SAFIRE strengths 3 and 4, yielding four datasets per CT enterographic examination. The mean volume CT dose index (CTDIvol) and size-specific dose estimate (SSDE) at full dose were 13.1 mGy (median, 7.36 mGy) and 15.9 mGy (median, 13.06 mGy), respectively, and those at half dose were 6.55 mGy (median, 3.68 mGy) and 7.95 mGy (median, 6.5 mGy). Images were subjectively evaluated by eight radiologists for quality and diagnostic confidence for Crohn disease. Areas under the receiver operating characteristic curves (AUCs) were estimated, and the multireader, multicase analysis of variance method was used to compare reconstruction methods on the basis of a noninferiority margin of 0.05. Results The mean AUCs with half-dose scans (FBP, 0.908; SAFIRE 3, 0.935; SAFIRE 4, 0.924) were noninferior to the mean AUC with full-dose FBP scans (0.908; P Crohn disease, despite an inferior subjective image quality. (©) RSNA, 2016 Online

  14. Summary of round robin measurements of radiation induced conductivity in Wesgo AL995 alumina

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J. [Oak Ridge National Lab., TN (United States)

    1996-10-01

    This existing data on radiation induced conductivity (RIC) measurements performed on the same heat of the IEA reference ceramic insulator are summarized. Six different sets of RIC measurements have been performed on Wesgo AL995 at dose rates between 10 Gy/s and 1 MGy/s. In general, good agreement was obtained between the different groups of researchers. The data indicate that the RIC at a test temperature of 400-500{degrees}C is approximately linear with ionizing dose rate up to {approximately}1000 Gy/s, and exhibits an approximately square root dependence on dose rate between 1 kGy/s and 1 MGy/s.

  15. Process Design and Cost Estimating Algorithms for the Computer Assisted Procedure for Design and Evaluation of Wastewater Treatment Systems (CAPDET).

    Science.gov (United States)

    1982-01-01

    wastewaters for the removal of ammonia by air-stripping process. 2.11.4.1.5 Regeneration of spent clinoptilolite , an ammonia selective ion exchange...Settleable solids (ml/1) 20 10 5 Total nitrogen (as N) 60 40 20 Free ammonia (as NH3 ) 30 15 10 Total phosphorus (as P) 20 10 5 Chlorides (as Cl) 150...concentration, mg/i1. NH3E - effluent ammonia nitrogen concentration, mg/i. 0 2.1- 12 2.1.9.3.15.4 Phosphorus. P04E (0.7) (P04) O where PO4E

  16. Guidelines for Selecting Control and Treatment Options for Contaminated Dredged Material.

    Science.gov (United States)

    1986-09-01

    This level increases organics removal to 95 percent. viii NO ’% V 1 d. Level IV is treatment to remove nutrients such as ammonia and phosphorus. e...metals. Clinoptilolite (Cu ;’n Cd - Pb) and mordenite (;: Zn; and Co < Cu M n) both show selective exchange of heavv metals. As wtti all ion exchangers...Equalization Sulfides >100 mg/i Precipitation or stripping with recovery Phenols >70-300 mg/i Extraction, adsorption, internal dilution Ammonia >1.6 g/k

  17. Grand Forks - East Grand Forks Urban Water Resources Study. Wastewater Management Appendix.

    Science.gov (United States)

    1981-07-01

    denitrification or clinoptilolite ion exchange is required to meet the ammonia and total nitrogen levels. The effluent from these unit processes would be filtered...32 45 Dissolved Oxygen (mg/1) At Grand Forks 6.0 7.0 8.6 i0.0 12.1 At East Grand Forks 6.5 7.4 9.0 11.4 12.7 Ammonia Nitrogen (mg/i) At Grand Forks...Concentration (mg/i) Total Solids 700 Dissolved Solids 500 Suspended Solids 200 BOD5 200 COD 500 Total Nitrogen 40 Organic Nitrogen 15 Ammonia Nitrogen

  18. Photon hormesis deactivates alpha-particle induced bystander effects between zebrafish embryos

    Science.gov (United States)

    Ng, C. Y. P.; Cheng, S. H.; Yu, K. N.

    2017-04-01

    In the present work, we studied the effects of low-dose X-ray photons on the alpha-particle induced bystander effects between embryos of the zebrafish, Danio rerio. The effects on the naive whole embryos were studied through quantification of apoptotic signals (amounts of cells undergoing apoptosis) at 24 h post fertilization (hpf) using vital dye acridine orange staining, followed by counting the stained cells under a fluorescent microscope. We report data showing that embryos at 5 hpf subjected to a 4.4 mGy alpha-particle irradiation could release a stress signal into the medium, which could induce bystander effect in partnered naive embryos sharing the same medium. We also report that the bystander effect was deactivated when the irradiated embryos were subjected to a concomitant irradiation of 10 or 14 mGy of X-rays, but no such deactivation was achieved if the concomitant X-ray dose dropped to 2.5 or 5 mGy. In the present study, the significant drop in the amount of apoptotic signals on the embryos having received 4.4 mGy alpha particles together X-rays irradiation from 2.5 or 5 mGy to 10 or 14 mGy, together with the deactivation of RIBE with concomitant irradiation of 10 or 14 mGy of X-rays supported the participation of photon hormesis with an onset dose between 5 and 10 mGy, which might lead to removal of aberrant cells through early apoptosis or induction of high-fidelity DNA repair. As we found that photons and alpha particles could have opposite biological effects when these were simultaneously irradiated onto living organisms, these ionizing radiations could be viewed as two different environmental stressors, and the resultant effects could be regarded as multiple stressor effects. The present work presented the first study on a multiple stressor effect which occurred on bystander organisms. In other words, this was a non-targeted multiple stressor effect. The photon hormesis could also explain some failed attempts to observe neutron-induced bystander

  19. Thoracic x-ray in pediatrics: entrance doses evaluation in the skin of the patients; Raios X de torax em pediatria: avaliacao de doses de entrada na pele dos pacientes

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, Eliane; Borges, Jose C. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear; Mota, Helvecio C.; Briquet, Claudia [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil); Rosa, Luis Antonio [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil)

    1998-07-01

    The doses received by children in diagnostic radiology are an important concern on radiological protection due to the potential risk involved, however there is few information about the doses involved in the pediatric exams. This work evaluates the entrance skin doses in children chest examination (ESD), using thermoluminescent dosimeters. The doses presented a range from 0,01 mGy to 0,67 mGy. It was observed that for some age groups the evaluated doses were above the values recommended by European Community. (author)

  20. Bone marrow dose in chest radiography: the posteroanterior vs. anteroposterior projection

    Energy Technology Data Exchange (ETDEWEB)

    Archer, B.R.; Whitmore, R.C.; North, L.B.; Bushong, S.C.

    1979-10-01

    The dose to active bone marrow resulting from anteroposterior (AP) and posteroanterior (PA) chest examinations was estimated using an Alderson Rando phantom and extruded lithium fluoride dosimeters. The AP projections resulted in a mean marrow dose range of 1.9 to 2.6 mrad (0.019 to 0.026 mGy) as compared to doses for PA projections of 3.4 to 3.8 mrad (0.034 to 0.038 mGy) for optimally diagnostic exposures taken at 70, 90, and 120 kVp.

  1. Thermoluminescent Detectors in Mixed Fields

    CERN Document Server

    Mala, P; Biskup, B; Roeed, K

    2012-01-01

    This note reports on using of thermoluminescent detectors for radiation monitoring in the LHC tunnel and in the shielded areas around the tunnel. The accumulated annual doses in these areas vary a lot so a dosimeter used there should cover a large dose range. TL detectors can measure dose from 0.1 mGy to few kGy (with a recently proposed new technique which needs more studies up to 1 MGy). This report presents studies of these detectors in mixed fields similar to radiation field in the LHC and the possible usage of their results for calculation of high energy hadron and thermal neutron fluence.

  2. Investigation of the radiation hardness of GaAs sensors in an electron beam

    CERN Document Server

    K. Afanaciev, K; P. Bernitt, P; G. Chelkov, G; J. Gajewski, J; M. Gostkin, M; Ch Grah, Ch; R. Heller, R; H. Henschel, H; A. Ignatenko, A; Z. Krumshteyn, Z; S. Kulis, S; W. Lange, W; W. Lohmann, W; D. Mokeev, D; V. Novikov, V; M. Ohlerich, M; A. Rosca, A; A. Sapronov, A; R.S. Schmidt, R S; S. Schuwalow, S; O. Tolbanov, O; A. Tyazhev, A

    2012-01-01

    A compact and finely grained sandwich calorimeter is designed to instrument the very forward region of a detector at a future e+e− collider. The calorimeter will be exposed to low energy e+e− pairs originating from beamstrahlung, resulting in absorbed doses of about one MGy per year. GaAs pad sensors interleaved with tungsten absorber plates are considered as an option for this calorimeter. Several Cr-doped GaAs sensor prototypes were produced and irradiated with 8.5–10 MeV electrons up to a dose of 1.5 MGy. The sensor performance was measured as a function of the absorbed dose.

  3. Perspective: Materials informatics and big data: Realization of the "fourth paradigm" of science in materials science

    Science.gov (United States)

    Agrawal, Ankit; Choudhary, Alok

    2016-05-01

    Our ability to collect "big data" has greatly surpassed our capability to analyze it, underscoring the emergence of the fourth paradigm of science, which is data-driven discovery. The need for data informatics is also emphasized by the Materials Genome Initiative (MGI), further boosting the emerging field of materials informatics. In this article, we look at how data-driven techniques are playing a big role in deciphering processing-structure-property-performance relationships in materials, with illustrative examples of both forward models (property prediction) and inverse models (materials discovery). Such analytics can significantly reduce time-to-insight and accelerate cost-effective materials discovery, which is the goal of MGI.

  4. Average glandular dose in digital mammography and breast tomosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Olgar, T. [Ankara Univ. (Turkey). Dept. of Engineering Physics; Universitaetsklinikum Leipzig AoeR (Germany). Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie; Kahn, T.; Gosch, D. [Universitaetsklinikum Leipzig AoeR (Germany). Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie

    2012-10-15

    Purpose: To determine the average glandular dose (AGD) in digital full-field mammography (2 D imaging mode) and in breast tomosynthesis (3 D imaging mode). Materials and Methods: Using the method described by Boone, the AGD was calculated from the exposure parameters of 2247 conventional 2 D mammograms and 984 mammograms in 3 D imaging mode of 641 patients examined with the digital mammographic system Hologic Selenia Dimensions. The breast glandular tissue content was estimated by the Hologic R2 Quantra automated volumetric breast density measurement tool for each patient from right craniocaudal (RCC) and left craniocaudal (LCC) images in 2 D imaging mode. Results: The mean compressed breast thickness (CBT) was 52.7 mm for craniocaudal (CC) and 56.0 mm for mediolateral oblique (MLO) views. The mean percentage of breast glandular tissue content was 18.0 % and 17.4 % for RCC and LCC projections, respectively. The mean AGD values in 2 D imaging mode per exposure for the standard breast were 1.57 mGy and 1.66 mGy, while the mean AGD values after correction for real breast composition were 1.82 mGy and 1.94 mGy for CC and MLO views, respectively. The mean AGD values in 3 D imaging mode per exposure for the standard breast were 2.19 mGy and 2.29 mGy, while the mean AGD values after correction for the real breast composition were 2.53 mGy and 2.63 mGy for CC and MLO views, respectively. No significant relationship was found between the AGD and CBT in 2 D imaging mode and a good correlation coefficient of 0.98 in 3 D imaging mode. Conclusion: In this study the mean calculated AGD per exposure in 3 D imaging mode was on average 34 % higher than for 2 D imaging mode for patients examined with the same CBT.

  5. DNA alterations and effects on growth and reproduction in Daphnia magna during chronic exposure to gamma radiation over three successive generations

    Energy Technology Data Exchange (ETDEWEB)

    Parisot, Florian [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV/SERIS/LECO, Cadarache, St Paul-lez-Durance 13115 (France); Bourdineaud, Jean-Paul [UMR 5805 EPOC – OASU, Station marine d’Arcachon, Université Bordeaux 1, Arcachon 33120 (France); Plaire, Delphine; Adam-Guillermin, Christelle [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV/SERIS/LECO, Cadarache, St Paul-lez-Durance 13115 (France); Alonzo, Frédéric, E-mail: frederic.alonzo@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV/SERIS/LECO, Cadarache, St Paul-lez-Durance 13115 (France)

    2015-06-15

    Highlights: • We exposed three successive generations of Daphnia magna to chronic gamma radiation. • We examined DNA alterations and effects on survival, growth and reproduction. • DNA alterations were accumulated over a generation and transmitted to the progeny. • Effects on survival and reproduction, and delay in growth increased over generations. - Abstract: This study examined chronic effects of external Cs-137 gamma radiation on Daphnia magna exposed over three successive generations (F0, F1 and F2) to environmentally relevant dose rates (ranging from 0.007 to 35.4 mGy h{sup −1}). Investigated endpoints included survival, growth, reproduction and DNA alterations quantified using random-amplified polymorphic DNA polymerase chain reaction (RAPD-PCR). Results demonstrated that radiation effects on survival, growth and reproduction increased in severity from generation F0 to generation F2. Mortality after 21 days at 35.4 mGy h{sup −1} increased from 20% in F0 to 30% in F2. Growth was affected by a slight reduction in maximum length at 35.4 mGy h{sup −1} in F0 and by reductions of 5 and 13% in growth rate, respectively, at 4.70 and 35.4 mGy h{sup −1} in F2. Reproduction was affected by a reduction of 19% in 21 day-fecundity at 35.4 mGy h{sup −1} in F0 and by a delay of 1.9 days in brood release as low as 0.070 mGy h{sup −1} in F2. In parallel, DNA alterations became significant at decreasing dose rates over the course of F0 (from 4.70 mGy h{sup −1} at hatching to 0.007 mGy h{sup −1} after ∼21 days) and from F0 to F2 (0.070 mGy h{sup −1} at hatching to 0.007 mGy h{sup −1} after ∼21 days), demonstrating their rapid accumulation in F0 daphnids and their transmission to offspring generations. Transiently more efficient DNA repair leading to some recovery at the organism level was suggested in F1, with no effect on survival, a slight reduction of 12% in 21 day-fecundity at 35.4 mGy h{sup −1} and DNA alterations significant at highest

  6. Analysis of foetal dose assessed by I.R.S.N. from 2004 to 2008; Analyse des evaluations de dose uterine realisees par l'I.R.S.N. de 2004 a 2008

    Energy Technology Data Exchange (ETDEWEB)

    Etard, C.; Aubert, B. [IRSN, Unite d' Expertise en Radioprotection Medicale, DRPH/SER/UEM, 92 - Fontenay-aux-Roses (France)

    2009-10-15

    After a medical exposure of a pregnant patient, the practitioner can seek I.R.S.N. to estimate the foetal dose. From 2004 to 2008, 326 foetal doses have been estimated by I.R.S.N. following radiological or nuclear medicine examinations, among them 246 corresponded to situations where uterus was directly exposed. These estimations were performed by calculations based on the technical parameters of the exam. In conventional radiology, foetal doses estimated are lower than 35 mGy and their averages are in agreement with international data. In computed tomography, doses are generally in the range 15 to 65 mGy, but can exceed 100 mGy in certain configurations. In this field, practitioners must pay a particular attention to the optimization of pelvic exams of female patients and estimate individually the foetal dose in case of pregnancy. Furthermore, the dispersal of doses for the same type of radiological exam shows heterogeneous practices, sometimes very far from the recommendations of the French society of radiology. In nuclear medicine, foetal doses estimated are lower than 10 mGy, without taking into account the dose due to a possible associated CT examination. (authors)

  7. Study of an optimization protocol for radiographic techniques in computerized radiology; Estudo de um protocolo de otimizacao para as tecnicas radiograficas em radiologia computadorizada

    Energy Technology Data Exchange (ETDEWEB)

    Abrantes, Marcos Eugenio Silva

    2015-07-01

    This work is designed to produce information for the improvement of image quality to deployment in a radiology department based on previous reviews of the images by questionnaires of acceptance and quality e recognition of the parameters used in chest radiographic techniques. The data collected were divided by male, female, PA and LAT thickness, body mass index, biotypes, anthropomorphic parameters and body evaluation associated with constant voltage and the additional filtration. The results show the predominance of 35 and 40 constants with additional filtration from 0.5 to 1.5 mmAl, voltage in male: (PA and LAT) 86-92 kV and 96-112 kV, female: 85-98 kV and 96-112 kV. The charge applied to the tube for males: (PA and LAT) 5-10 mA.s and 5-16 mA.s, female: (PA and LAT) 6.3-8 mA.s and 9-14 mA.s. Absorbed doses for males: (PA and PF) 0.04-0.17 mGy and 0.03-0.19 mGy and from female (PA and PF) from 0.03-0.22 mGy and 0, 04-0.17 mGy. This procedure can be used in radiology department to implement and acceptance in the quality of images. (author)

  8. Genomic and metabolic diversity of Marine Group I Thaumarchaeota in the mesopelagic of two subtropical gyres.

    Directory of Open Access Journals (Sweden)

    Brandon K Swan

    Full Text Available Marine Group I (MGI Thaumarchaeota are one of the most abundant and cosmopolitan chemoautotrophs within the global dark ocean. To date, no representatives of this archaeal group retrieved from the dark ocean have been successfully cultured. We used single cell genomics to investigate the genomic and metabolic diversity of thaumarchaea within the mesopelagic of the subtropical North Pacific and South Atlantic Ocean. Phylogenetic and metagenomic recruitment analysis revealed that MGI single amplified genomes (SAGs are genetically and biogeographically distinct from existing thaumarchaea cultures obtained from surface waters. Confirming prior studies, we found genes encoding proteins for aerobic ammonia oxidation and the hydrolysis of urea, which may be used for energy production, as well as genes involved in 3-hydroxypropionate/4-hydroxybutyrate and oxidative tricarboxylic acid pathways. A large proportion of protein sequences identified in MGI SAGs were absent in the marine cultures Cenarchaeum symbiosum and Nitrosopumilus maritimus, thus expanding the predicted protein space for this archaeal group. Identifiable genes located on genomic islands with low metagenome recruitment capacity were enriched in cellular defense functions, likely in response to viral infections or grazing. We show that MGI Thaumarchaeota in the dark ocean may have more flexibility in potential energy sources and adaptations to biotic interactions than the existing, surface-ocean cultures.

  9. Crystal growth and thermoluminescence response of NaZr{sub 2}(PO{sub 4}){sub 3} at high gamma radiation doses

    Energy Technology Data Exchange (ETDEWEB)

    Ordóñez-Regil, E., E-mail: eduardo.ordonez@inin.gob.mx [Depto. de Química, Gerencia de Ciencias Básicas, Instituto Nacional de Investigaciones Nucleares, AP 18-1027, CP 11801 México D.F. (Mexico); Contreras-Ramírez, A., E-mail: aida.contreras@inin.gob.mx [Depto. de Química, Gerencia de Ciencias Básicas, Instituto Nacional de Investigaciones Nucleares, AP 18-1027, CP 11801 México D.F. (Mexico); Depto. de Tecnología de Materiales, Gerencia de Ciencias Aplicadas, Instituto Nacional de Investigaciones Nucleares, AP 18-1027, CP 11801 México D.F. (Mexico); Facultad de Ciencias, Universidad Autónoma del Estado de México, Unidad Académica el Cerrillo, Piedras Blancas, AP 2-139, CP 50000 Toluca Estado de México (Mexico); Fernández-Valverde, S.M., E-mail: suilma.fernandez@inin.gob.mx [Depto. de Química, Gerencia de Ciencias Básicas, Instituto Nacional de Investigaciones Nucleares, AP 18-1027, CP 11801 México D.F. (Mexico); González-Martínez, P.R., E-mail: pedro.gonzalez@inin.gob.mx [Depto. de Física, Gerencia de Ciencias Básicas, Instituto Nacional de Investigaciones Nucleares, AP 18-1027, CP 11801 México D.F. (Mexico); Carrasco-Ábrego, H., E-mail: hector.carrasco@inin.gob.mx [Depto. Aceleradores, Gerencia de Ciencias Ambientales, Instituto Nacional de Investigaciones Nucleares, AP 18-1027, CP 11801 México D.F. (Mexico)

    2013-11-15

    Graphical abstract: -- Highlights: •NaZr{sub 2}(PO{sub 4}){sub 3} exposed to gamma doses of 10, 30 and 50 MGy. •Gamma radiation produced growth of the crystal size of the NZP. •Morphology changes were reversible by heating. •Linear relationship between the thermoluminescence and the applied gamma dose. •This property could be useful for high-level gamma dosimetry. -- Abstract: This work describes the synthesis and characterization of NaZr{sub 2}(PO{sub 4}){sub 3}. The stability of this material under high doses of gamma radiation was investigated in the range of 10–50 MGy. Samples of unaltered and gamma irradiated NaZr{sub 2}(PO{sub 4}){sub 3} were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and thermoluminescence. The results showed that while functional groups were not affected by the gamma irradiation, morphology changes were observed with increasing doses of gamma irradiation. The morphology of the non-irradiated compound is agglomerated flakes; however, irradiation at 10 MGy splits the flakes inducing the formation of well-defined cubes. Gamma irradiation induced the crystal size of the NaZr{sub 2}(PO{sub 4}){sub 3} to grow. The heat treatment (973 K) of samples irradiated at 50 MGy resulted in the recovery of the original morphology. Furthermore, the thermoluminescence analysis of the irradiated compound is reported.

  10. Assessment of patient dose and radiogenic risks during endoscopic retrograde cholangiopancreatography

    Energy Technology Data Exchange (ETDEWEB)

    Sulieman, A.; Elzaki, M. [Sudan University of Science and Technology, College of Medical Radiologic Science, P. O. Box 1908, Khartoum 11111 (Sudan); Alkhorayef, M.; Babikir, E. [King Saud University, College of Applied Sciences, Radiological Sciences Department, P. O. Box 10219, Riyadh 11433 (Saudi Arabia); Abuzaid, M. [University of Sharjah, College of Health Sciences, Medical Diagnostic Imaging Department, Sharjah (United Arab Emirates); Dalton, A.; Bradley, D., E-mail: Abdelmoneim_a@yahoo.com [University of Surrey, Centre for Nuclear and Radiation Physics, Department of Physics, GU2-7XH, Guildford, Surrey (United Kingdom)

    2015-10-15

    Endoscopic retrograde cholangiopancreatography (ERCP) is an invasive technique that has been used for over 30 years in the diagnosis and management of pancreaticobiliary disorders. The objectives of this study were to evaluate the patient entrance surface air kerma doses (ESAK) and estimate the organ and effective doses during ERCP in three hospitals in Khartoum. A total of 55 patients were examined in three hospitals in Khartoum state, Sudan. Calibrated thermoluminescence dosimeters (TLD)-Gr-200-A)) were used to measure patients ESAK. The overall mean of ESAK for all ERCP procedures was 42.4 mGy. The mean patient ESAK in Fedail, Soba and Ibn sena centers were 26.7 mGy, 26.0 mGy, 72.4 mGy, respectively. The effective doses in three centers were 1.6, 1.56 and 2.67 mSv in that order and the overall mean effective dose was 2.01 mSv. Patient radiation doses vary widely among the different hospitals. Patient ESAK is low compared to previous studies in the light of the current practice. Patient dose was decreased significantly in the last two decades. (Author)

  11. Anti-gingivitis effects of a novel 0.454% stabilized stannous fluoride dentifrice relative to a positive control.

    Science.gov (United States)

    He, Tao; Barker, Matthew L; Goyal, C Ram; Biesbrock, Aaron R

    2012-06-01

    To compare the anti-gingivitis efficacy of a novel 0.454% stannous fluoride dentifrice to a commercially available positive control triclosan-containing dentifrice in a population of adults with gingivitis. This single-center, randomized and controlled, double-blind, parallel group, 2-month trial enrolled 200 adults with mild-to-moderate gingivitis. At baseline, pre-treatment gingivitis levels were assessed with both the Lobene Modified Gingival Index (MGI) and the Gingival Bleeding Index (GBI). Subjects were randomly assigned to one of two test dentifrices: either 0.454% highly bioavailable stannous fluoride or the 0.30% triclosan positive control. Following at-home, unsupervised toothbrushing according to manufacturer's instructions with their assigned test dentifrice for 2 months, subjects were re-evaluated for gingivitis again via the MGI and GBI examinations. A total of 196 subjects completed the trial and were evaluable. At Month 2, both test dentifrices produced statistically significant reductions in number of bleeding sites, GBI, and MGI on average relative to pre-treatment (Pdentifrice group was 62% greater for number of bleeding sites, 60% greater for GBI, and 45% greater for MGI versus the triclosan/copolymer positive control group; groups differed significantly (Pdentifrices were well-tolerated.

  12. Electron probe X-ray microanalysis of boar and inobuta testes after the Fukushima accident

    Science.gov (United States)

    Yamashiro, Hideaki; Abe, Yasuyuki; Hayashi, Gohei; Urushihara, Yusuke; Kuwahara, Yoshikazu; Suzuki, Masatoshi; Kobayashi, Jin; Kino, Yasuyuki; Fukuda, Tomokazu; Tong, Bin; Takino, Sachio; Sugano, Yukou; Sugimura, Satoshi; Yamada, Takahisa; Isogai, Emiko; Fukumoto, Manabu

    2015-01-01

    We aimed to investigate the effect of chronic radiation exposure associated with the Fukushima Daiichi Nuclear Power Plant (FNPP) accident on the testes of boar and inobuta (a hybrid of Sus scrofa and Sus scrofa domestica). This study examined the contamination levels of radioactive caesium (Cs), especially 134Cs and 137Cs, in the testis of both boar and inobuta during 2012, after the Fukushima accident. Morphological analysis and electron-probe X-ray microanalysis (EPMA) were also undertaken on the testes. The 134Cs and 137Cs levels were 6430 ± 23 and 6820 ± 32 Bq/kg in the boar testes, and 755 ± 13 and 747 ± 17 Bq/kg in the inobuta testes, respectively. The internal and external exposure of total 134Cs and 137Cs in the boar testes were 47.1 mGy and 176.2 mGy, respectively, whereas in the inobuta testes, these levels were 6.09 mGy and 59.8 mGy, respectively. Defective spermatogenesis was not detected by the histochemical analysis of radiation-exposed testes for either animal. In neither animal were Cs molecules detected, using EPMA. In conclusion, we showed that adverse radiation-induced effects were not detected in the examined boar and inobuta testes following the chronic radiation exposure associated with the FNPP accident. PMID:26825300

  13. Efficacy of breast shielding during CT of the head

    Energy Technology Data Exchange (ETDEWEB)

    Brnic, Z.; Hebrang, A.; Anic, P. [Department of Diagnostic and Interventional Radiology, University Hospital Merkur, Zajceva 19, 10000, Zagreb (Croatia); Vekic, B. [' ' Ruder Boskovic' ' Research Institute, 10000, Zagreb (Croatia)

    2003-11-01

    In light of increasing frequency of CT examinations in the past decades, the aims of this prospective study were to investigate scatter radiation breast exposure in head CT and its dependence upon body constitution, and to assess the efficacy of lead shielding as a means of breast dose reduction. In 49 women referred to head CT for objective medical reasons one breast was covered with lead apron during CT scanning. Radiation doses were measured by use of thermoluminescent dosimeters, at skin of both breasts and over the apron. The doses were then compared as well as correlated to body mass index and meatus acusticus externus-to-dosimeter distance, respectively. Average exposure at the skin of the unshielded breast was 0.28 mGy (range 0.15-0.41 mGy), compared with 0.13 mGy (range 0.05-0.29 mGy) at the shielded breast. The doses showed a mean reduction by 57% due to lead shielding. At least half of breast exposure was imparted to the breast from outside, whereas the remainder results from internal scatter. The higher the body mass index, the higher the percentage of internal scatter in total breast dose. Although the level of scatter radiation to the breast is generally low during head CT examination, the use of lead cover enables recognizable further reduction of the exposure, and is recommended as a feasible and effective procedure of breast protection during CT of the head. (orig.)

  14. Peripheral dose measurements in cervical cancer radiotherapy: a comparison of volumetric modulated arc therapy and step-and-shoot IMRT techniques

    Science.gov (United States)

    2014-01-01

    Purpose The aim of this study was to investigate the peripheral doses resulting from volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy (IMRT) techniques in cervical cancer radiotherapy. Methods Nine patients with cervical cancer had treatment planned with both VMAT and IMRT. A specially designed phantom was used for this study, with ion chambers placed at interest points approximating the position of the breast, thyroid, and lens. The peripheral doses at the phantom interest points were measured and compared between the VMAT and IMRT techniques. Results VMAT provides a potential dosimetric advantage compared with IMRT. The mean (± standard deviation) peripheral dose to the breast point for 1 fraction (2 Gy) during VMAT measured 5.13 ± 0.96 mGy, compared with 9.04 ± 1.50 mGy for IMRT. At the thyroid and lens interest points, the mean (± standard deviation) peripheral dose during VMAT was 2.19 ± 0.33 and 2.16 ± 0.28 mGy, compared with 7.07 ± 0.76 and 6.97 ± 0.91 mGy for IMRT, respectively. VMAT reduced the monitor units used by 28% and shortened the treatment delivery time by 54% compared with IMRT. Conclusion While the dosimetric results are similar for both techniques, VMAT results in a lower peripheral dose to the patient and reduces the monitor-unit usage and treatment delivery time compared with IMRT. PMID:24555547

  15. The influence of the Lop Nor Nuclear Weapons Test Base to the population of the Republic of Kazakhstan

    Energy Technology Data Exchange (ETDEWEB)

    Zhumadilov, Kassym, E-mail: kassym@hiroshima-u.ac.j [Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8553 (Japan); Ivannikov, Alexander [Medical Radiological Research Center, Korolev str. 4, Obninsk 249036 (Russian Federation); Zharlyganova, Dinara [Astana Medical University, Astana 010000 (Kazakhstan); Stepanenko, Valeriy [Medical Radiological Research Center, Korolev str. 4, Obninsk 249036 (Russian Federation); Zhumadilov, Zhaxybay [Nazarbayev University, Life Science Center, Astana 010000 (Kazakhstan); Apsalikov, Kazbek [Kazakh Scientific-Research Institute for Radiation Medicine and Ecology, Semey 071400 (Kazakhstan); Toyoda, Shin [Department of Applied Physics, Faculty of Science, Okayama University of Science, 1-1 Ridai, Okayama 700-0005 (Japan); Endo, Satoru [Department of Quantum Energy Applications, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Tanaka, Kenichi [Division of Physics, Department of Liberal Arts and Sciences, Center of Medical Education, Sapporo Medical University, South 1, West 17, Chuo-ku, Sapporo 060-8556 (Japan); Miyazawa, Chuzou [School of Dentistry, Ohu University, 31-1, Aza-Misumido, Tomita-machi, Koriyama-shi, Fukushima Pref. 963-8611 (Japan); Okamoto, Tetsuji [Department of Molecular Oral Medicine and Maxillofacial Surgery, Division of Frontier Medical Sciences, Graduate School of Biomedical Sciences, Hiroshima University (Japan); Hoshi, Masaharu [Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8553 (Japan)

    2011-04-15

    The method of electron spin resonance (ESR) dosimetry was applied to human tooth enamel to obtain estimates of individual absorbed dose for residents of Makanchi, Urdzhar and Taskesken settlements located near the Kazakhstan-Chinese border (about 400 km to the South-East, from the Semipalatinsk Nuclear Test Site (SNTS) and about 1000 km from the Lop Nor Nuclear Weapons Test Base, China). Since the ground and atmospheric nuclear tests (1964-1981) at Lop Nor, the people residing in these settlements are believed to have been heavily exposed to radioactive fallout. Tooth samples had been extracted for medical reasons during the course of ordinary dental treatment. The village of Kokpekty, located 400 km to the South-east of the SNTS, was chosen as the control group since it has not been subjected to any radioactive contamination. The mean excess doses in tooth enamel obtained after subtraction of the contribution of natural background radiation do not exceed 62 {+-} 28 mGy, 64 {+-} 30 mGy, 49 {+-} 27 mGy and -19 {+-} 36 mGy for all ages of the residents of Makanchi, Urdzhar, Taskesken and the control village of Kokpekty, respectively.

  16. Dosimetry of cone beam computed tomography scanning for diagnosis and planning in implant dentistry

    Energy Technology Data Exchange (ETDEWEB)

    Santos Pinto de A, E. L.; Manzi, F. R.; Goncalves Z, E. [Pontifical Catholic University of Minas Gerais, Av. Jose Gaspar 500, 30535-901 Belo Horizonte, Minas Gerais (Brazil); Nogueira, M. S.; Fernandes Z, M. A., E-mail: madelon@cdtn.br [Development Center of Nuclear Technology / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901Belo Horizonte, Minas Gerais (Brazil)

    2015-10-15

    Full text: The radiation dose and estimate the radiation induced risk of cancer and morpho functional alterations according to BEIR VII (2006) and recommendations of the ICRP 103 (2007) were measured in cone beam computed tomography (CBCT) scanning (Tc Kodak 9000C 3D) in different oral and maxillofacial regions for diagnosis and planning in implant dentistry for each examination protocol: jaw full, maxilla full and jaw and maxilla full associated. Thermoluminescent dosimeters (TLD- 100 H) were placed in an Alderson-Rando in regions corresponding to the crystalline, parotid, submandibular and thyroid glands and ovaries. The highest values for entrance skin dose were observed in the region of the parotid and submandibular glands, 9.612 mGy to 7.912 mGy and 8.818 mGy to 0.483 mGy, respectively. All examination protocols presented on the right and left sides in the region of the submandibular gland the highest values for absorbed dose (D). In the jaw full exam the thyroid glands on both sides presented highest dose values than maxilla full exam. This study allowed measuring the entrance skin dose and the absorbed dose (D) highlighting a dosimetric preponderance to the salivary glands. With danger of to radiation that induces cancer risk was observed that the age group most likely to have to risk of cancer was 20 years, compared to 30, 40, 50, 60,70 and 80 years. (Author)

  17. Mukaiyama Aldol Reaction of 1, 2-Bis(trimethylsiloxy) Cyclobutene Catalyzed by Magnesium(II) Iodide

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Efficient Mukaiyama-type aldol reaction of 1, 2-bis(trimethylsiloxy)cyclobutene with aromatic aldehydes catalyzed by MgI2 is reported. The resulting succinoylation product of aldehyde was converted into the synthetic useful γ-lactone and butenolide derivatives.

  18. The anaerobic treatment of low strength soluble wastewaters.

    NARCIS (Netherlands)

    Kato, M.T.

    1994-01-01

    Low strength soluble wastewaters with chemical oxygen demand (COD) of less than 2000 mg/I are mostly from food processing industries. They commonly contain simple substrates such as short- chain fatty acids, alcohols and carbohydrates. The application of anaerobic technology has been mostly directed

  19. Radiation doses to children with shunt-treated hydrocephalus

    Energy Technology Data Exchange (ETDEWEB)

    Holmedal, Lise J. [Helse Fonna, Department of Radiology, Stord Hospital, Stord (Norway); Friberg, Eva G.; Boerretzen, Ingelin; Olerud, Hilde [The Norwegian Radiation Protection Authority, Oesteraas (Norway); Laegreid, Liv [Haukeland University Hospital, Department of Paediatrics, Bergen (Norway); Rosendahl, Karen [University of Bergen, Department of Surgical Sciences, Radiology Section, Bergen (Norway); Great Ormond Street Hospital for Children, Department of Diagnostic Radiology, London (United Kingdom)

    2007-12-15

    Children with shunt-treated hydrocephalus are still followed routinely with frequent head CT scans. To estimate the effective dose, brain and lens doses from these examinations during childhood, and to assess dose variation per examination. All children born between 1983 and 1995 and treated for hydrocephalus between 1983 and 2002 were included. We retrospectively registered the number of examinations and the applied scan parameters. The effective dose was calculated using mean conversion factors from the CT dose index measured free in air, while doses to the lens and brain were estimated using tabulated CT dose index values measured in a head phantom. A total of 687 CT examinations were performed in 67 children. The mean effective dose, lens dose and brain dose to children over 6 months of age were 1.2 mSv, 52 mGy and 33 mGy, respectively, and the corresponding doses to younger children were 3.2 mSv, 60 mGy and 48 mGy. The effective dose per CT examination varied by a factor of 64. None of the children was exposed to doses known to cause deterministic effects. However, since the threshold for radiation-induced damage is not known with certainty, alternative modalities such as US and MRI should be used whenever possible. (orig.)

  20. Enhancing anaerobic treatment of wastewaters containing oleic acid

    NARCIS (Netherlands)

    Hwu, C.S.

    1997-01-01

    INTRODUCTION

    Lipids are one of the major organic pollutants in municipal and industrial wastewaters. Although domestic sewage typically contains about 40-100 mg/I lipids (Forster, 1992; Quéméneur and Marty, 1994), it is industrial wastewaters that are of greater

  1. Level and distribution of the radiation dose to the population from a mammography screening programme in New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Bulling, S.M.; Nicoll, J.J. [Otago Univ., Dunedin (New Zealand). Dept. of Physics

    1995-12-31

    The Otago Southland Breast Screening Programme offers biennial mammography to 19,000 eligible women on the South Island of New Zealand. A Quality Assurance programme ensures that international performance standards are met, in particular the radiation dose for a mammogram of 5 cm CIRS-X phantom is 1.7 mGy and careful retake analysis undertaken. This however does not reveal the absorbed dose received by individuals, nor how this varies between individuals. Machine parameters and compressed breast thickness for each film were recorded for 310 women who attended one centre during the three months ending February 1993 and absorbed doses calculated using Monte Carlo data. The mean compressed breast thickness for the 310 women was 4.9 cm, doses received for individual films ranged from 0.7 to 8.5 mGy while patient total doses were in the range 4 to 29 mGy with 75% of women receiving a dose of 7.1 mGy or less. (Author).

  2. Skeletal muscle deiodinase type 2 regulation during illness in mice

    NARCIS (Netherlands)

    J. Kwakkel; H.C. van Beeren; M.T. Ackermans; M. Platvoet-ter Schiphorst; E. Fliers; W.M. Wiersinga; A. Boelen

    2009-01-01

    We have previously shown that skeletal muscle deiodinase type 2 (D2) mRNA (listed as Dio2 in MGI Database) is up-regulated in an animal model of acute illness. However, human Studies on the expression Of muscle D2 during illness report conflicting data. Therefore, we evaluated the expression of skel

  3. Radation distribution in head & thorax computerized tomography

    Directory of Open Access Journals (Sweden)

    Mohammad Mahdavi

    2014-05-01

    Full Text Available Background: Determination of the exposure levels in the computerized tomography (CT practices is necessary to define the respected national reference levels, quality control of CT centers and the risk assessment for radiation induced cancers. Material and Methods: On the basis of this necessity, the radiation exposure distribution due to common CT practices has been investigated at Razi Hospital CT center in Rasht using tissue-equivalent phantoms and the thermoluminescent dosimeters (TLD. The Head and Thorax phantoms were used with the standard dimensions incorporating holes at the center and edges for TLD placement. Dosimetry was carried out using LiF Mg, Cu, P small chips due to their relatively tissue equivalence, high sensitivity convenient annealing procedure and the non-complex glow curve. Results: Results showed that CTDI for Head is 52.85 mGy and for Body is 68.15mGy. CTDLW for Head is 13.67 mGy and for Body is 16.94mGy . Conclusion: In comparison with other radiographical procedures, patient absorbed doses in CT imaging are usually very high. Content of dose is increased by increase of mAs.

  4. Patient cumulative radiation exposure in interventional cardiology; Exposition cumulee aux rayonnements ionisants des patients en cardiologie interventionnelle: caracteristiques cliniques et dosimetriques

    Energy Technology Data Exchange (ETDEWEB)

    Bernier, M.O.; Jacob, S.; Laurier, D. [Institut de radioprotection et de surete nucleaire (IRSN), DRPH, SRBE, LEPID, Fontenay-aux-Roses (France); Maccia, C. [Centre d' assurance de qualite des applications technologiques dans le domaine de la sante - CAATS, Bourg-la-Reine (France); Bar, O.; Blanchard, D. [Clinique Saint-Gatien, Tours (France); Catelinois, O. [Institut de veille sanitaire, St Maurice (France)

    2012-01-15

    Interventional cardiology procedures can involve potentially high doses of radiation to the patients. Stochastic effects of ionising radiation - radiation-induced cancers in the long term - may occur. We analysed clinical characteristics and dosimetric data in a population of patients undergoing interventional cardiology. In all, 1 591 patients who had undergone coronarography and/or angioplasty in the course of a year at the Saint-Gatien Clinic in Tours (France) were included. Information on patients' individual clinical characteristics and Dose-Area Product values were collected. Organ doses to the lung, oesophagus, bone marrow and breast were mathematically evaluated. The median age of patients was 70 years. Their median cumulative dose-area product value was 48.4 Gy.cm{sup 2} for the whole year and the median effective dose was 9.7 mSv. The median organ doses were 41 mGy for the lung, 31 mGy for the oesophagus, 10 mGy for the bone marrow and 4 mGy for the breast. Levels of doses close to the heart appear to be rather high in the case of repeated interventional cardiology procedures. Clinical characteristics should be taken into account when planning epidemiological studies on potential radiation-induced cancers. (authors)

  5. Enhancing Anaerobic Treatment of Wastewaters Containing Oleic Acid.

    NARCIS (Netherlands)

    Ching-Shyung, H.

    1997-01-01

    INTRODUCTIONLipids are one of the major organic pollutants in municipal and industrial wastewaters. Although domestic sewage typically contains about 40-100 mg/I lipids (Forster, 1992; Quéméneur and Marty, 1994), it is industrial wastewaters that are of greater concern when consider

  6. Characterization of heat loads from mitigated and unmitigated vertical displacement events in DIII-D

    Science.gov (United States)

    Hollmann, E. M.; Commaux, N.; Eidietis, N. W.; Humphreys, D. A.; Jernigan, T. J.; Lasnier, C. J.; Moyer, R. A.; Pitts, R. A.; Sugihara, M.; Strait, E. J.; Watkins, J.; Wesley, J. C.

    2013-06-01

    Experiments have been conducted on the DIII-D tokamak to study the distribution and repeatability of heat loads and vessel currents resulting from vertical displacement events (VDEs). For unmitigated VDEs, the radiated power fraction appears to be of order 50%, with the remaining power dominantly conducted to the vessel walls. Shot-to-shot scatter in heat loads measured at one toroidal location is not large (<±50%), suggesting that toroidal asymmetries in conducted heat loads are not large. Conducted heat loads are clearly observed during the current quench (CQ) of both mitigated and unmitigated disruptions. Significant poloidal asymmetries in heat loads and radiated power are often observed in the experiments but are not yet understood. Energy dissipated resistively in the conducting walls during the CQ appears to be small (<5%). The mitigating effect of neon massive gas injection (MGI) as a function of MGI trigger delay has also been studied. Improved mitigation is observed as the MGI trigger delay is decreased. For sufficiently early MGI mitigation, close to 100% radiated energy and a reduction of roughly a factor 2 in vessel forces is achieved.

  7. Characterization of heat loads from mitigated and unmitigated vertical displacement events in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Hollmann, E. M.; Moyer, R. A. [University of California-San Diego, La Jolla, California 92093 (United States); Commaux, N.; Jernigan, T. J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Eidietis, N. W.; Humphreys, D. A.; Strait, E. J.; Wesley, J. C. [General Atomics, San Diego, California 92186 (United States); Lasnier, C. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Pitts, R. A.; Sugihara, M. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul Lez Durance (France); Watkins, J. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)

    2013-06-15

    Experiments have been conducted on the DIII-D tokamak to study the distribution and repeatability of heat loads and vessel currents resulting from vertical displacement events (VDEs). For unmitigated VDEs, the radiated power fraction appears to be of order 50%, with the remaining power dominantly conducted to the vessel walls. Shot-to-shot scatter in heat loads measured at one toroidal location is not large (<±50%), suggesting that toroidal asymmetries in conducted heat loads are not large. Conducted heat loads are clearly observed during the current quench (CQ) of both mitigated and unmitigated disruptions. Significant poloidal asymmetries in heat loads and radiated power are often observed in the experiments but are not yet understood. Energy dissipated resistively in the conducting walls during the CQ appears to be small (<5%). The mitigating effect of neon massive gas injection (MGI) as a function of MGI trigger delay has also been studied. Improved mitigation is observed as the MGI trigger delay is decreased. For sufficiently early MGI mitigation, close to 100% radiated energy and a reduction of roughly a factor 2 in vessel forces is achieved.

  8. Repair of I-SceI induced DSB at a specific site of chromosome in human cells: influence of low-dose, low-dose-rate gamma-rays.

    Science.gov (United States)

    Yatagai, Fumio; Suzuki, Masao; Ishioka, Noriaki; Ohmori, Hitoshi; Honma, Masamitsu

    2008-11-01

    We investigated the influence of low-dose, low-dose-rate gamma-ray irradiation on DNA double strand break (DSB) repair in human lymphoblastoid TK6 cells. A single DSB was introduced at intron 4 of the TK+ allele (chromosome 17) by transfection with the I-SceI expression vector pCBASce. We assessed for DSB repair due to non-homologous end-joining (NHEJ) by determining the generation of TK-deficient mutants in the TK6 derivative TSCE5 (TK +/-) carrying an I-SceI recognition site. We similarly estimated DSB repair via homologous recombination (HR) at the same site in the derived compound heterozygote (TK-/-) cell line TSCER2 that carries an additional point mutation in exon 5. The NHEJ repair of DSB was barely influenced by pre-irradiation of the cells with 30 mGy gamma-rays at 1.2 mGy h(-1). DSB repair by HR, in contrast, was enhanced by approximately 50% after pre-irradiation of the cells under these conditions. Furthermore, when I-SceI digestion was followed by irradiation at a dose of 8.5 mGy, delivered at a dose rate of only 0.125 mGy h(-1), HR repair efficiency was enhanced by approximately 80%. This experimental approach can be applied to characterize DSB repair in the low-dose region of ionizing radiation.

  9. Gamma irradiation effects on cyanate ester/epoxy insulation materials for superconducting magnets

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jingwen [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wu, Zhixiong, E-mail: zxwu@mail.ipc.ac.cn [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Huang, Chuanjun [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Li, Laifeng, E-mail: laifengli@mail.ipc.ac.cn [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-12-15

    Highlights: • Irradiation resistance of glass fiber reinforced cyanate ester/epoxy composite was investigated. • The cyanate ester/epoxy resin system has a low viscosity and long pot life. • The T{sub g} of the matrix resin decreased slightly with the increase of irradiation dose. • The ILSS of GFRP composite increased slightly when exposed to 10 MGy of gamma irradiation. - Abstract: Cyanate ester/epoxy resin was used as a cryogenic-grade polymer matrix and glass fiber reinforced polymer (GFRP) composite was manufactured. The processing properties of matrix resin in terms of the isothermal viscosity at 45 °C were investigated. The specimens were exposed with gamma irradiation of 1 MGy, 5 MGy and 10 MGy, respectively. The effect of gamma irradiation on thermal properties and structure of cyanate ester/epoxy matrix was investigated. The interlaminar shear strength (ILSS) of the composites before and after irradiation were investigated at room temperature, 77 K and 4.2 K. Results showed that cyanate ester/epoxy system had a low viscosity and a long pot life at 45 °C. The glass transition temperature of the matrix resin decreased with the increasing irradiation dose. Moreover, the ILSS of GFRP composite slightly increases after irradiation and toughening mechanism was also discussed.

  10. SU-E-I-15: Comparison of Radiation Dose for Radiography and EOS in Adolescent Scoliosis Patients

    Energy Technology Data Exchange (ETDEWEB)

    Schueler, B; Walz-Flannigan, A [Mayo Clinic, Rochester, MN (United States)

    2014-06-01

    Purpose: To estimate patient radiation dose for whole spine imaging using EOS, a new biplanar slot-scanning radiographic system and compare with standard scoliosis radiography. Methods: The EOS imaging system (EOS Imaging, Paris, France) consists of two orthogonal x-ray fan beams which simultaneously acquire frontal and lateral projection images of a standing patient. The patient entrance skin air kerma was measured for each projection image using manufacturer-recommended exposure parameters for spine imaging. Organ and effective doses were estimated using a commercially-available Monte Carlo simulation program (PCXMC, STUK, Radiation and Nuclear Safety Authority, Helsinki, Finland) for a 15 year old mathematical phantom model. These results were compared to organ and effective dose estimated for scoliosis radiography using computed radiography (CR) with standard exposure parameters obtained from a survey of pediatric radiographic projections. Results: The entrance skin air kerma for EOS was found to be 0.18 mGy and 0.33 mGy for posterior-anterior (PA) and lateral projections, respectively. This compares to 0.76 mGy and 1.4 mGy for CR, PA and lateral projections. Effective dose for EOS (PA and lateral projections combined) is 0.19 mSv compared to 0.51 mSv for CR. Conclusion: The EOS slot-scanning radiographic system allows for reduced patient radiation dose in scoliosis patients as compared to standard CR radiography.

  11. 76 FR 38214 - Report to Congress on Abnormal Occurrences; Fiscal Year 2010; Dissemination of Information

    Science.gov (United States)

    2011-06-29

    ... consequences, the cause or causes, and the actions taken to prevent recurrence. Each event is also being... replacement hormone therapy and continues such treatment. Cause(s)--The cause of the event was found to be a... iodine-131 for hyperthyroidism resulted in a dose to an embryo of 80 mGy (8 rem) whole body. Prior to the...

  12. Dosimetric measurements and comparison studies in digital imaging system

    Science.gov (United States)

    Jung, Ji-Young; Kim, Hee-Joung; Lee, Chang-Lae; Cho, Hyo-Min; Nam, Sora

    2008-03-01

    Number of radiologic exams using digital imaging systems has rapidly increased with advanced imaging technologies. However, it has not been paid attention to the radiation dose in clinical situations. It was the motivation to study radiation dosimetry in the DR system. The objective of this study was to measure beam quality and patient's dose using DR system and to compare them to both IEC standard and IAEA guidelines. The measured average dose for chest and abdomen was 1.376 mGy and 9.501 mGy, respectively, compared to 0.4 mGy and 10.0 mGy in IAEA guidelines. The results also indicated that the DR system has a lower radiation beam quality than that of the IEC standard. The results showed that the patients may be exposed higher radiation for chest exams and lower radiation for abdomen exams using DR system. IAEA Guidelines were prepared based on western people which may be different weight and height for patients compared them to Korean. In conclusion, a new guideline for acceptable DR dosimetry for Korean patients may need to be developed with further studies for large populations. We believe that this research greatly help to introduce the importance of the dosimetry in diagnostic radiology in Korea. And, a development of database for dosimetry in diagnostic radiology will become an opportunity of making aware of radiation safety of medical examination to patient.

  13. Quantifying murine bone marrow and blood radiation dose response following {sup 18}F-FDG PET with DNA damage biomarkers

    Energy Technology Data Exchange (ETDEWEB)

    Manning, Grainne [Biological Effects Department, Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, Didcot, Oxfordshire OX11 ORQ (United Kingdom); Taylor, Kristina [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON (Canada); Finnon, Paul [Biological Effects Department, Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, Didcot, Oxfordshire OX11 ORQ (United Kingdom); Lemon, Jennifer A.; Boreham, Douglas R. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON (Canada); Badie, Christophe, E-mail: christophe.badie@phe.gov.uk [Biological Effects Department, Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, Didcot, Oxfordshire OX11 ORQ (United Kingdom)

    2014-12-15

    Highlights: • Mice received either a range of {sup 18}F-FDG activities or whole body X-ray doses. • Blood samples were collected at 24 and 43 h for MN-RET and QPCR analysis. • Regression analysis showed that both types of exposure produced a linear response. • BM doses of 33 mGy ({sup 18}F-FDG) and 25 mGy X-rays were significantly higher than controls. • No significant difference between internal ({sup 18}F-FDG) and external (X-ray) was found. - Abstract: The purpose of this study was to quantify the poorly understood radiation doses to murine bone marrow and blood from whole-body fluorine 18 ({sup 18}F)-fluorodeoxyglucose (FDG) positron emission tomography (PET), by using specific biomarkers and comparing with whole body external low dose exposures. Groups of 3–5 mice were randomly assigned to 10 groups, each receiving either a different activity of {sup 18}F-FDG: 0–37 MBq or whole body irradiated with corresponding doses of 0–300 mGy X-rays. Blood samples were collected at 24 h and at 43 h for reticulocyte micronucleus assays and QPCR analysis of gene expression in peripheral blood leukocytes. Blood and bone marrow dose estimates were calculated from injected activities of {sup 18}F-FDG and were based on a recommended ICRP model. Doses to the bone marrow corresponding to 33.43 mGy and above for internal {sup 18}F-FDG exposure and to 25 mGy and above for external X-ray exposure, showed significant increases in radiation-induced MN-RET formation relative to controls (P < 0.05). Regression analysis showed that both types of exposure produced a linear response with linear regression analysis giving R{sup 2} of 0.992 and 0.999 for respectively internal and external exposure. No significant difference between the two data sets was found with a P-value of 0.493. In vivo gene expression dose–responses at 24 h for Bbc3 and Cdkn1 were similar for {sup 18}F-FDG and X-ray exposures, with significant modifications occurring for doses over 300 mGy for Bbc3

  14. Absorbed dose and dose rate using the Varian OBI 1.3 and 1.4 CBCT system.

    Science.gov (United States)

    Palm, Asa; Nilsson, Elisabeth; Herrnsdorf, Lars

    2010-01-28

    According to published data, the absorbed dose used for a CBCT image acquisition with Varian OBI v1.3 can be as high as 100 mGy. In 2008 Varian released a new OBI version (v1.4), which promised to reduce the imaging dose. In this study, absorbed doses used for CBCT image acquisitions with the default irradiation techniques of Varian OBI v1.3 and v1.4 are measured. TLDs are used to derive dose distributions at three planes inside an anthropomorphic phantom. In addition, point doses and dose profiles inside a 'stack' of three CTDI body phantoms are measured using a new solid state detector, the CT Dose Profiler. With the CT Dose Profiler, the individual pulses from the X-ray tube are also studied. To verify the absorbed dose measured with the CT Dose Profiler, it is compared to TLD. The image quality is evaluated using a Catphan phantom. For OBI v1.3, doses measured in transverse planes of the Alderson phantom range between 64 mGy and 144 mGy. The average dose is around 100 mGy. For OBI v1.4, doses measured in transverse planes of the Alderson phantom range between 1 mGy and 51 mGy. Mean doses range between 3-35 mGy depending on CBCT mode. CT Dose Profiler data agree with TLD measurements in a CTDI phantom within the uncertainty of the TLD measurements (estimated SD +/- 10%). Instantaneous dose rate at the periphery of the phantom can be higher than 20 mGy/s, which is 10 times the dose rate at the center. The spatial resolution in v1.4 is not as high as in v1.3. In conclusion, measurements show that the imaging doses for default modes in Varian OBI v1.4 CBCT system are significantly lower than in v1.3. The CT Dose Profiler is proven fast and accurate for CBCT applications.

  15. Fetal shielding combined with state of the art CT dose reduction strategies during maternal chest CT

    Energy Technology Data Exchange (ETDEWEB)

    Chatterson, Leslie C., E-mail: lch088@mail.usask.ca [Department of Diagnostic Imaging, University of Saskatchewan (Canada); Leswick, David A.; Fladeland, Derek A. [Department of Diagnostic Imaging, University of Saskatchewan (Canada); Hunt, Megan M.; Webster, Stephen [Saskatchewan Ministry of Labour Relations and Workplace Safety (Canada); Lim, Hyun [Department of Community Health and Epidemiology, College of Medicine, University of Saskatchewan (Canada)

    2014-07-15

    Purpose: Custom bismuth-antimony shields were previously shown to reduce fetal dose by 53% on an 8DR (detector row) CT scanner without dynamic adaptive section collimation (DASC), automatic tube current modulation (ATCM) or adaptive statistical iterative reconstruction (ASiR). The purpose of this study is to compare the effective maternal and average fetal organ dose reduction both with and without bismuth-antimony shields on a 64DR CT scanner using DASC, ATCM and ASiR during maternal CTPA. Materials and methods: A phantom with gravid prosthesis and a bismuth-antimony shield were used. Thermoluminescent dosimeters (TLDs) measured fetal radiation dose. The average fetal organ dose and effective maternal dose were determined using 100 kVp, scanning from the lung apices to the diaphragm utilizing DASC, ATCM and ASiR on a 64DR CT scanner with and without shielding in the first and third trimester. Isolated assessment of DASC was done via comparing a new 8DR scan without DASC to a similar scan on the 64DR with DASC. Results: Average third trimester unshielded fetal dose was reduced from 0.22 mGy ± 0.02 on the 8DR to 0.13 mGy ± 0.03 with the conservative 64DR protocol that included 30% ASiR, DASC and ATCM (42% reduction, P < 0.01). Use of a shield further reduced average third trimester fetal dose to 0.04 mGy ± 0.01 (69% reduction, P < 0.01). The average fetal organ dose reduction attributable to DASC alone was modest (6% reduction from 0.17 mGy ± 0.02 to 0.16 mGy ± 0.02, P = 0.014). First trimester fetal organ dose on the 8DR protocol was 0.07 mGy ± 0.03. This was reduced to 0.05 mGy ± 0.03 on the 64DR protocol without shielding (30% reduction, P = 0.009). Shields further reduced this dose to below accurately detectable levels. Effective maternal dose was reduced from 4.0 mSv on the 8DR to 2.5 mSv on the 64DR scanner using the conservative protocol (38% dose reduction). Conclusion: ASiR, ATCM and DASC combined significantly reduce effective maternal and fetal

  16. Low-dose radiation from 18F-FDG PET does not increase cancer frequency or shorten latency but reduces kidney disease in cancer-prone Trp53+/- mice.

    Science.gov (United States)

    Taylor, Kristina; Lemon, Jennifer A; Phan, Nghi; Boreham, Douglas R

    2014-07-01

    There is considerable interest in the health effects associated with low-level radiation exposure from medical imaging procedures. Concerns in the medical community that increased radiation exposure from imaging procedures may increase cancer risk among patients are confounded by research showing that low-dose radiation exposure can extend lifespan by increasing the latency period of some types of cancer. The most commonly used radiopharmaceutical for positron emission tomography (PET) scans is 2-[(18)F] fluoro-2-deoxy-d-glucose ((18)F-FDG), which exposes tissue to a low-dose, mixed radiation quality: 634 keV β+ and 511 keV γ-rays. The goal of this research was to investigate how modification of cancer risk associated with exposure to low-dose ionising radiation in cancer-prone Trp53+/- mice is influenced by radiation quality from PET. At 7-8 weeks of age, Trp53+/- female mice were exposed to one of five treatments: 0 Gy, 10 mGy γ-rays, 10 mGy (18)F-FDG, 4 Gy γ-rays, 10 mGy (18)F-FDG + 4 Gy γ-rays (n > 185 per group). The large 4-Gy radiation dose significantly reduced the lifespan by shortening the latency period of cancer and significantly increasing the number of mice with malignancies, compared with unirradiated controls. The 10 mGy γ-rays and 10 mGy PET doses did not significantly modify the frequency or latency period of cancer relative to unirradiated mice. Similarly, the PET scan administered prior to a large 4-Gy dose did not significantly modify the latency or frequency of cancer relative to mice receiving a dose of only 4 Gy. The relative biological effectiveness of radiation quality from (18)F-FDG, with respect to malignancy, is approximately 1. However; when non-cancer endpoints were studied, it was found that the 10-mGy PET group had a significant reduction in kidney lesions (P dose (20 ± 0.13 mGy), relative to the whole-body average, which occurs in specific tissues, may not be detrimental. © The Author 2014. Published by Oxford University

  17. Influência do procedimento radiográfico na dose de entrada na pele de pacientes em raios-X pediátricos Influence of radiographic parameters on the entrance surface dose in x-rays of pediatric patients

    Directory of Open Access Journals (Sweden)

    Mércia Liane Oliveira

    2003-03-01

    Full Text Available OBJETIVO: Este trabalho tem como objetivo discutir os efeitos dos principais parâmetros que interferem na qualidade da imagem e na dose de entrada na pele do paciente. MATERIAIS E MÉTODOS: Foram acompanhadas radiografias pediátricas de tórax em três instituições. Em cada uma delas foram feitos testes de desempenho dos equipamentos de raios-X utilizados. A avaliação da dose de entrada na pele foi feita com a utilização de dosímetros termoluminescentes. RESULTADOS: Apenas um dos equipamentos de raios-X testados mostrou-se em condições aceitáveis de funcionamento. Os valores médios de dose de entrada na pele para os exames investigados, em função da faixa etária, foram: (0,222 ± 0,088 mGy para menores de 1 ano, (0,28 ± 0,11 mGy entre 1,1 e 4 anos, (0,26 ± 0,13 mGy entre 4,1 e 6 anos, (0,23 ± 0,13 mGy entre 6,1 e 10 anos e (0,26 ± 0,25 mGy para maiores de 10 anos. CONCLUSÃO: Os valores médios de dose de entrada na pele são bastante elevados se comparados aos níveis de referência adotados pela Comissão da Comunidade Européia e aos demais resultados encontrados na literatura pesquisada. Recomenda-se a implantação de programas de garantia de qualidade para a redução da dose-paciente com a obtenção de imagens com qualidade para o diagnóstico.OBJECTIVE: The aim of this work is to discuss the effects of the main parameters that influence image quality and the entrance skin dose. MATERIALS AND METHODS: The pediatric chest radiographs of three different Institutions were evaluated. Tests on all x-ray equipment were performed. The skin entrance dose was assessed using thermoluminescent dosimeters. RESULTS: Only one of all x-ray equipments tested was in good operation condition. The average skin entrance dose was: (0.222 ± 0.088 mGy for children under 1 year, (0.28 ± 0.11 mGy for 1.1 to 4 years, (0.26 ± 0.13 mGy for 4.1 to 6 years, (0.23 ± 0.13 mGy for 6.1 to 10 years and (0.26 ± 0.25 mGy for older than 10 years

  18. EPR dosimetry of radiation background in the Urals region

    Energy Technology Data Exchange (ETDEWEB)

    Shishkina, E.A.; Degteva, M.O.; Shved, V.A. [Urals Research Center for Radiation Medicine, 48-A Vorovsky, Chelyabinsk 454076 (Russian Federation); Fattibene, P.; Onori, S. [Istituto Superiore di Sanita and Istituto Nazionale di Fisica Nucleare (Italy); Wieser, A. [GSF, Forschungszentrum fuer Umwelt und Gesundheit, Ingolstaedter Landstr (Germany); Ivanov, D.V.; Bayankin, S.N. [Institute of Metal Physics, Russian Academy of Sciences (Russian Federation); Knyazev, V.A.; Vasilenko, E.I.; Gorelov, M. [ZAO, Closed Corporation ' Company GEOSPETSECOLOGIA' (Russian Federation)

    2006-07-01

    Method of Electron Paramagnetic Resonance is extensively applied to individual retrospective dosimetry. The background dose is unavoidable component of cumulative absorbed dose in the tooth enamel accumulated during the lifetime of donor. Estimation of incidental radiation dose using tooth enamel needs in extraction of background dose. Moreover, the variation of background doses in the population is a limited factor for reliable detection of additional irradiation especially for low dose level. Therefore the accurate knowledge of the natural background radiation dose is a critical element of EPR studies of exposed populations. In the Urals region the method applies for such two large cohorts as the workers of Mayak (Ozersk citizens) and Techa River riverside inhabitants (rural population). Current study aimed to investigate the Urals radiation background detected by EPR spectrometry. For this aim two group of unexposed Urals residents were separated, viz: citizens of Ozersk and rural inhabitants of Chelyabinsk region. Comparison of two investigated territories has demonstrated that from the point of view of radiation background it is impossible to assume the Urals population as uniform. The reliable difference between the urban and rural residents has been found. The average background doses of Ozersk donors is in average 50 mGy higher than those detected for rural residents. The individual variability of background doses for Osersk has been higher than in the rural results. The difference in background dose levels between two population results in different limits of accidental dose detection and individualization. The doses for 'Mayak' workers (Ozyorsk citizens) can be classed as anthropogenic if the EPR measurements exceed 120 mGy for teeth younger than 40 years, and 240 mGy for teeth older than 70 years. The anthropogenic doses for Techa River residents (rural population) would be higher than 95 mGy for teeth younger than 50 years and 270 mGy for

  19. A unified gene catalog for the laboratory mouse reference genome.

    Science.gov (United States)

    Zhu, Y; Richardson, J E; Hale, P; Baldarelli, R M; Reed, D J; Recla, J M; Sinclair, R; Reddy, T B K; Bult, C J

    2015-08-01

    We report here a semi-automated process by which mouse genome feature predictions and curated annotations (i.e., genes, pseudogenes, functional RNAs, etc.) from Ensembl, NCBI and Vertebrate Genome Annotation database (Vega) are reconciled with the genome features in the Mouse Genome Informatics (MGI) database (http://www.informatics.jax.org) into a comprehensive and non-redundant catalog. Our gene unification method employs an algorithm (fjoin--feature join) for efficient detection of genome coordinate overlaps among features represented in two annotation data sets. Following the analysis with fjoin, genome features are binned into six possible categories (1:1, 1:0, 0:1, 1:n, n:1, n:m) based on coordinate overlaps. These categories are subsequently prioritized for assessment of annotation equivalencies and differences. The version of the unified catalog reported here contains more than 59,000 entries, including 22,599 protein-coding coding genes, 12,455 pseudogenes, and 24,007 other feature types (e.g., microRNAs, lincRNAs, etc.). More than 23,000 of the entries in the MGI gene catalog have equivalent gene models in the annotation files obtained from NCBI, Vega, and Ensembl. 12,719 of the features are unique to NCBI relative to Ensembl/Vega; 11,957 are unique to Ensembl/Vega relative to NCBI, and 3095 are unique to MGI. More than 4000 genome features fall into categories that require manual inspection to resolve structural differences in the gene models from different annotation sources. Using the MGI unified gene catalog, researchers can easily generate a comprehensive report of mouse genome features from a single source and compare the details of gene and transcript structure using MGI's mouse genome browser.

  20. Evaluation of the peripheral dose in stereotactic radiotherapy and radiosurgery treatments

    Energy Technology Data Exchange (ETDEWEB)

    Di Betta, Erika; Fariselli, Laura; Bergantin, Achille; Locatelli, Federica; Del Vecchio, Antonella; Broggi, Sara; Fumagalli, Maria Luisa [Department of Neurosurgery, Division of Medical Physics, Fondazione IRCCS, Istituto Neurologico C. Besta, 20133 Milano (Italy); Department of Neurosurgery, Division of Radiotherapy, Fondazione IRCCS, Istituto Neurologico C. Besta, 20133 Milano (Italy); CyberKnife Centre, Centro Diagnostico Italiano, 20147 Milano (Italy); Division of Medical Physics, Fondazione IRCCS, Istituto S. Raffaele, 20132 Milano (Italy); Department of Neurosurgery, Division of Medical Physics, Fondazione IRCCS, Istituto Neurologico C. Besta, 20133 Milano (Italy)

    2010-07-15

    Purpose: The main purpose of this work was to compare peripheral doses absorbed during stereotactic treatment of a brain lesion delivered using different devices. These data were used to estimate the risk of stochastic effects. Methods: Treatment plans were created for an anthropomorphic phantom and delivered using a LINAC with stereotactic cones and a multileaf collimator, a CyberKnife system (before and after a supplemental shielding was applied), a TomoTherapy system, and a Gamma Knife unit. For each treatment, 5 Gy were prescribed to the target. Measurements were performed with thermoluminescent dosimeters inserted roughly in the position of the thyroid, sternum, upper lung, lower lung, and gonads. Results: Mean doses ranged from of 4.1 (Gamma Knife) to 62.8 mGy (LINAC with cones) in the thyroid, from 2.3 (TomoTherapy) to 30 mGy (preshielding CyberKnife) in the sternum, from 1.7 (TomoTherapy) to 20 mGy (preshielding CyberKnife) in the upper part of the lungs, from 0.98 (Gamma Knife) to 15 mGy (preshielding CyberKnife) in the lower part of the lungs, and between 0.3 (Gamma Knife) and 10 mGy (preshielding CyberKnife) in the gonads. Conclusions: The peripheral dose absorbed in the sites of interest with a 5 Gy fraction is low. Although the risk of adverse side effects calculated for 20 Gy delivered in 5 Gy fractions is negligible, in the interest of optimum patient radioprotection, further studies are needed to determine the weight of each contributor to the peripheral dose.

  1. Estimation of effective dose during hysterosalpingography procedures; Estimación de dosis efectiva durante los procedimientos hysterosalpingography

    Energy Technology Data Exchange (ETDEWEB)

    Alzimamil, K.; Babikir, E.; Alkhorayef, M. [King Saud University, College of Applied Medical Sciences, Radiological Sciences Department, P. O. Box 10219, Riyadh 11433, (Saudi Arabia); Sulieman, A. [Salman bin Abdulaziz University, College of Applied Medical Sciences, Radiology and Medical Imaging Department, P. O. Box 422, Alkharj (Saudi Arabia); Alsafi, K. [King Abdulaziz University, Faculty of Medicine, Radiology Department, Jeddah 22254 (Saudi Arabia); Omer, H., E-mail: kalzimami@ksu.edu.sa [Dammam University, Faculty of Medicine, Dammam Khobar Coastal Rd, Khobar 31982 (Saudi Arabia)

    2014-08-15

    Hysterosalpingography (HSG) is the most frequently used diagnostic tool to evaluate the endometrial cavity and fallopian tube by using conventional x-ray or fluoroscopy. Determination of the patient radiation doses values from x-ray examinations provides useful guidance on where best to concentrate efforts on patient dose reduction in order to optimize the protection of the patients. The aims of this study were to measure the patients entrance surface air kerma doses (ESA K), effective doses and to compare practices between different hospitals in Sudan. ESA K were measured for patient using calibrated thermo luminance dosimeters (TLDs, Gr-200A). Effective doses were estimated using National Radiological Protection Board (NRPB) software. This study was conducted in five radiological departments: Two Teaching Hospitals (A and D), two private hospitals (B and C) and one University Hospital (E). The mean ESD was 20.1 mGy, 28.9 mGy, 13.6 mGy, 58.65 mGy, 35.7, 22.4 and 19.6 mGy for hospitals A,B,C,D, and E), respectively. The mean effective dose was 2.4 mSv, 3.5 mSv, 1.6 mSv, 7.1 mSv and 4.3 mSv in the same order. The study showed wide variations in the ESDs with three of the hospitals having values above the internationally reported values. Number of x-ray images, fluoroscopy time, operator skills x-ray machine type and clinical complexity of the procedures were shown to be major contributors to the variations reported. Results demonstrated the need for standardization of technique throughout the hospital. The results also suggest that there is a need to optimize the procedures. Local DRLs were proposed for the entire procedures. (author)

  2. Comparing five different iterative reconstruction algorithms for computed tomography in an ROC study.

    Science.gov (United States)

    Jensen, Kristin; Martinsen, Anne Catrine T; Tingberg, Anders; Aaløkken, Trond Mogens; Fosse, Erik

    2014-12-01

    The purpose of this study was to evaluate lesion conspicuity achieved with five different iterative reconstruction techniques from four CT vendors at three different dose levels. Comparisons were made of iterative algorithm and filtered back projection (FBP) among and within systems. An anthropomorphic liver phantom was examined with four CT systems, each from a different vendor. CTDIvol levels of 5 mGy, 10 mGy and 15 mGy were chosen. Images were reconstructed with FBP and the iterative algorithm on the system. Images were interpreted independently by four observers, and the areas under the ROC curve (AUCs) were calculated. Noise and contrast-to-noise ratios (CNR) were measured. One iterative algorithm increased AUC (0.79, 0.95, and 0.97) compared to FBP (0.70, 0.86, and 0.93) at all dose levels (p algorithm increased AUC from 0.78 with FBP to 0.84 (p = 0.007) at 5 mGy. Differences at 10 and 15 mGy were not significant (p-values: 0.084-0.883). Three algorithms showed no difference in AUC compared to FBP (p-values: 0.008-1.000). All of the algorithms decreased noise (10-71%) and improved CNR. Only two algorithms improved lesion detection, even though noise reduction was shown with all algorithms. Iterative reconstruction algorithms affected lesion detection differently at different dose levels. One iterative algorithm improved lesion detectability compared to filtered back projection. Three algorithms did not significantly improve lesion detectability. One algorithm improved lesion detectability at the lowest dose level.

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

    Science.gov (United States)

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

    2012-03-01

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

  4. Combined effects of alpha particles and depleted uranium on Zebrafish (Danio rerio) embryos

    Science.gov (United States)

    Ng, Candy Y.P.; Pereira, Sandrine; Cheng, Shuk Han; Adam-Guillermin, Christelle; Garnier-Laplace, Jacqueline; Yu, Kwan Ngok

    2016-01-01

    The combined effects of low-dose or high-dose alpha particles and depleted uranium (DU) in Zebrafish (Danio rerio) embryos were studied. Three schemes were examined—(i) [ILUL]: 0.44 mGy alpha-particle dose + 10 µg/l DU exposure, (ii) [IHUH]: 4.4 mGy alpha-particle dose + 100 µg/l DU exposure and (iii) [IHUL]: 4.4 mGy alpha-particle dose + 10 µg/l DU exposure—in which Zebrafish embryos were irradiated with alpha particles at 5 h post fertilization (hpf) and/or exposed to uranium at 5–6 hpf. The results were also compared with our previous work, which studied the effects of [ILUH]: 0.44 mGy alpha-particle dose + 100 µg/l DU exposure. When the Zebrafish embryos developed to 24 hpf, the apoptotic signals in the entire embryos, used as the biological endpoint for this study, were quantified. Our results showed that [ILUL] and [IHUL] led to antagonistic effects, whereas [IHUH] led to an additive effect. The effect found for the previously studied case of [ILUH] was difficult to define because it was synergistic with reference to the 100 µg/l DU exposure, but it was antagonistic with reference to the 0.44 mGy alpha-particle dose. All the findings regarding the four different schemes showed that the combined effects critically depended on the dose response to each individual stressor. We also qualitatively explained these findings in terms of promotion of early death of cells predisposed to spontaneous transformation by alpha particles, interacting with the delay in cell death resulting from various concentrations of DU exposure. PMID:26937024

  5. Entrance surface dose and image quality: comparison of adult chest and abdominal X-ray examinations in general practitioner clinics, public and private hospitals in Malaysia.

    Science.gov (United States)

    Hambali, Ahmad Shariff; Ng, Kwan-Hoong; Abdullah, Basri Johan Jeet; Wang, Hwee-Beng; Jamal, Noriah; Spelic, David C; Suleiman, Orhan H

    2009-01-01

    This study was undertaken to compare the entrance surface dose (ESD) and image quality of adult chest and abdominal X-ray examinations conducted at general practitioner (GP) clinics, and public and private hospitals in Malaysia. The surveyed facilities were randomly selected within a given category (28 GP clinics, 20 public hospitals and 15 private hospitals). Only departmental X-ray units were involved in the survey. Chest examinations were done at all facilities, while only hospitals performed abdominal examinations. This study used the x-ray attenuation phantoms and protocols developed for the Nationwide Evaluation of X-ray Trends (NEXT) survey program in the United States. The ESD was calculated from measurements of exposure and clinical geometry. An image quality test tool was used to evaluate the low-contrast detectability and high-contrast detail performance under typical clinical conditions. The median ESD value for the adult chest X-ray examination was the highest (0.25 mGy) at GP clinics, followed by private hospitals (0.22 mGy) and public hospitals (0.17 mGy). The median ESD for the adult abdominal X-ray examination at public hospitals (3.35 mGy) was higher than that for private hospitals (2.81 mGy). Results of image quality assessment for the chest X-ray examination show that all facility types have a similar median spatial resolution and low-contrast detectability. For the abdominal X-ray examination, public hospitals have a similar median spatial resolution but larger low-contrast detectability compared with private hospitals. The results of this survey clearly show that there is room for further improvement in performing chest and abdominal X-ray examinations in Malaysia.

  6. The effects of rat's sperm bioassay for low dose X-ray

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Gye Hwan; Min, Soo Young; Lee, Sang Bock; Lee, Sam Yul; Lee, Jun Haeng [Nambu Univ., Gwangju (Korea, Republic of); Park, Jong Bae [Juseong College, Cheongwon (Korea, Republic of)

    2007-12-15

    In order to investigate the enhancement effects of low dose radiation on biological activation, this study applied low dose X-ray to the whole body of male rats to find out whether hormesis is induced in male germ cells. Total 36 Sprague-Dawley (SD) rats as experimental animal were subdivided into 6 groups(in 6 rats per group) such as control, 10 mGy, 20 mGy, 50 mGy, 100 mGy and 200 mGy radiation group. All the groups showed slightly increasing number of sperms per 0.1 g semen (14.216 x 10{sup 6}, 13.901 x 10{sup 6}, 14.153 x 10{sup 6}, 13.831 x 10{sup 6}, 14.137 x 10{sup 6}, 14.677 x 10{sup 6} respectively), and the motility of sperms amounted to 50.9%, 49.5%, 55.1%, 54.3%, 48.0% and 52.2% respectively. Particularly, compared to the control, the other 5 groups showed higher male hormone level, and the microscopic observations of testicle tissues showed no vacuolization in seminiferous tubules and testis cells. In the results of this experiment, no harmful effect was observed on Sprague-Dawley (SD) rats for which the dose of radiation was controlled as regulated legally by the Ministry of Science and Technology and the Ministry of Health and Welfare. However, as these results were obtained from a limited number of animals, we cannot maintain that the same effect will be observed in the human body. Therefore, there should be further research on the effect on other animals and ultimately on the human body.

  7. Battery Charge Affects the Stability of Light Intensity from Light-emitting Diode Light-curing Units.

    Science.gov (United States)

    Tongtaksin, A; Leevailoj, C

    This study investigated the influence of battery charge levels on the stability of light-emitting diode (LED) curing-light intensity by measuring the intensity from fully charged through fully discharged batteries. The microhardness of resin composites polymerized by the light-curing units at various battery charge levels was measured. The light intensities of seven fully charged battery LED light-curing units-1) LY-A180, 2) Bluephase, 3) Woodpecker, 4) Demi Plus, 5) Saab II, 6) Elipar S10, and 7) MiniLED-were measured with a radiometer (Kerr) after every 10 uses (20 seconds per use) until the battery was discharged. Ten 2-mm-thick cylindrical specimens of A3 shade nanofilled resin composite (PREMISE, Kerr) were prepared per LED light-curing unit group. Each specimen was irradiated by the fully charged light-curing unit for 20 seconds. The LED light-curing units were then used until the battery charge fell to 50%. Specimens were prepared again as described above. This was repeated again when the light-curing units' battery charge fell to 25% and when the light intensity had decreased to 400 mW/cm(2). The top/bottom surface Knoop hardness ratios of the specimens were determined. The microhardness data were analyzed by one-way analysis of variance with Tukey test at a significance level of 0.05. The Pearson correlation coefficient was used to determine significant correlations between surface hardness and light intensity. We found that the light intensities of the Bluephase, Demi Plus, and Elipar S10 units were stable. The intensity of the MiniLED unit decreased slightly; however, it remained above 400 mW/cm(2). In contrast, the intensities of the LY-A180, Woodpecker, and Saab II units decreased below 400 mW/cm(2). There was also a significant decrease in the surface microhardnesses of the resin composite specimens treated with MiniLED, LY-A180, Woodpecker, and Saab II. In conclusion, the light intensity of several LED light-curing units decreased as the battery was

  8. The non-Euclidean revolution with an introduction by H.S.M. Coxeter

    CERN Document Server

    Trudeau, Richard J

    2001-01-01

    How unique and definitive is Euclidean geometry in describing the "real" space in which we live? Richard Trudeau confronts the fundamental question of truth and its representation through mathematical models in The Non-Euclidean Revolution. First, the author analyzes geometry in its historical and philosophical setting; second, he examines a revolution every bit as significant as the Copernican revolution in astronomy and the Darwinian revolution in biology; third, on the most speculative level, he questions the possibility of absolute knowledge of the world. Trudeau writes in a lively, entertaining, and highly accessible style. His book provides one of the most stimulating and personal presentations of a struggle with the nature of truth in mathematics and the physical world. A portion of the book won the Pólya Prize, a distinguished award from the Mathematical Association of America.

  9. Quantum Simulation of the Factorization Problem

    Science.gov (United States)

    Rosales, Jose Luis; Martin, Vicente

    2016-11-01

    Feynman's prescription for a quantum simulator was to find a Hamitonian for a system that could serve as a computer. The Pólya-Hilbert conjecture proposed the demonstration of Riemann's hypothesis through the spectral decomposition of Hermitian operators. Here we study the problem of decomposing a number into its prime factors, N =x y , using such a simulator. First, we derive the Hamiltonian of the physical system that simulates a new arithmetic function formulated for the factorization problem that represents the energy of the computer. This function rests alone on the primes below √{N }. We exactly solve the spectrum of the quantum system without resorting to any external ad hoc conditions, also showing that it obtains, for x ≪√{N }, a prediction of the prime counting function that is almost identical to Riemann's R (x ) function. It has no counterpart in analytic number theory, and its derivation is a consequence of the quantum theory of the simulator alone.

  10. Quantum mechanical potentials related to the prime numbers and Riemann zeros.

    Science.gov (United States)

    Schumayer, Dániel; van Zyl, Brandon P; Hutchinson, David A W

    2008-11-01

    Prime numbers are the building blocks of our arithmetic; however, their distribution still poses fundamental questions. Riemann showed that the distribution of primes could be given explicitly if one knew the distribution of the nontrivial zeros of the Riemann zeta(s) function. According to the Hilbert-Pólya conjecture, there exists a Hermitian operator of which the eigenvalues coincide with the real parts of the nontrivial zeros of zeta(s) . This idea has encouraged physicists to examine the properties of such possible operators, and they have found interesting connections between the distribution of zeros and the distribution of energy eigenvalues of quantum systems. We apply the Marchenko approach to construct potentials with energy eigenvalues equal to the prime numbers and to the zeros of the zeta(s) function. We demonstrate the multifractal nature of these potentials by measuring the Rényi dimension of their graphs. Our results offer hope for further analytical progress.

  11. High-Redshift Superwinds as the Source of the Strongest Mg II Absorbers A Feasibility Analysis

    CERN Document Server

    Bond, N A; Charlton, J C; Vogt, S S

    2001-01-01

    We present HIRES/Keck profiles of four extremely strong (W_r > 1.8 A) Mg II absorbers at 1 1.8 A evolve away from z = 2 to the present. We propose that a substantial fraction of these very strong absorbers are due to superwinds and that their evolution is related to the redshift evolution of star-forming galaxies. Based on the observed redshift number density of W_r > 1.8 A Mg II absorbers at 1 < z < 2, we explore whether it is realistic that superwinds from starbursting galaxies could give rise to these absorbers. Finally, we do an analysis of the superwind connection to damped Lya absorbers (DLAs). DLAs and superwinds evolve differently and usually have different kinematic structure, indicating that superwinds probably do not give rise to the majority of DLAs.

  12. The non-Euclidean revolution

    CERN Document Server

    Trudeau, Richard J

    1986-01-01

    How unique and definitive is Euclidean geometry in describing the "real" space in which we live? Richard Trudeau confronts the fundamental question of truth and its representation through mathematical models in The Non-Euclidean Revolution. First, the author analyzes geometry in its historical and philosophical setting; second, he examines a revolution every bit as significant as the Copernican revolution in astronomy and the Darwinian revolution in biology; third, on the most speculative level, he questions the possibility of absolute knowledge of the world. Trudeau writes in a lively, entertaining, and highly accessible style. His book provides one of the most stimulating and personal presentations of a struggle with the nature of truth in mathematics and the physical world. A portion of the book won the Pólya Prize, a distinguished award from the Mathematical Association of America. "Trudeau meets the challenge of reaching a broad audience in clever ways...(The book) is a good addition to our literature o...

  13. Delay-Dependent Absolute Stability ofUncertain Lur′e Systems with Time-Delays1)

    Institute of Scientific and Technical Information of China (English)

    CHENWu-Hua; GUANZhi-Hong; LUXiao-Mei; YANGXuan-Fang

    2004-01-01

    This paper is concerned with delay dependent absolute stability for a class of uncertain Lur′e systems with multiple time-delays. By using a descriptor model transformation of the sys-tem and by applying a recent result on bounding of cross products of vectors, a new type of Lya-punov-Krasovskii functional is constructed. Based on the new functional, delay-dependent suffi-cient conditions for absolute stability are derived in terms of linear matrix inequalities. These con-ditions do not require any parameter tuning, and can be solved numerically using the software LMI Lab. A numerical example is presented which shows that the proposed method can substantiallyimprove the delay bound for absolute stability of Lur′e system with time-delays, compared to theexisting ones.

  14. High-redshift SDSS Quasars with Weak Emission Lines

    DEFF Research Database (Denmark)

    Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Brandt, W. N.

    2009-01-01

    We identify a sample of 74 high-redshift quasars (z > 3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z > 4. These weak emission-line quasars (WLQs) constitute a prominent...... tail of the Lya + N v equivalent width distribution, and we compare them to quasars with more typical emission-line properties and to low-redshift active galactic nuclei with weak/absent emission lines, namely BL Lac objects. We find that WLQs exhibit hot (T ~ 1000 K) thermal dust emission and have...... rest-frame 0.1-5 µm spectral energy distributions that are quite similar to those of normal quasars. The variability, polarization, and radio properties of WLQs are also different from those of BL Lacs, making continuum boosting by a relativistic jet an unlikely physical interpretation. The most...

  15. Observable Signatures of the low-z Circum-Galactic and Inter-Galactic Medium : UV Line Emission in Simulations

    CERN Document Server

    Frank, S; Vibert, D; Milliard, B; Popping, A; Blaizot, J; Courty, S; Deharveng, J M; Peroux, C; Teyssier, R; Martin, C D

    2011-01-01

    We present for the first time predictions for UV line emission of intergalactic and circumgalactic gas from Adaptive Mesh Resolution (AMR) Large Scale Structure (LSS) simulations at redshifts 0.3Lya, OVI and CIV) there is a clear bimodality in the type of objects : the overwhelming majority of flux stems from discrete, compact sources, while a much larger volume fraction is filled by more tenuous gas. We characterise both object types with regard to number density, physical size and shape, brightness, luminosity, velocity structure, mass, temperature, ionisation state, and metal content. Degrading AMR grids to characteristic resolutions of available (such as FIREBall) or foreseeable instrumentation, allows to assess which inferences can be drawn from currently possible observations, and set foundations to prepare observing strategies for future missions. In general, the fain...

  16. Relations between the IR-UV-X-ray Continuum and Emission Lines for a Large Composite Sample of Narrow Line and Normal Seyfert i Galaxies

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We report on our research on the UV, optical line parameters and the infrared through UV to soft X-ray continuum parameters for a composite sample of narrow line and normal Seyfert 1 galaxies. The strong correlations among the line width of Hβ, optical line strength of Fe II and the soft X-ray slope are confirmed. We found no correlations between the UV line parameters, the equivalent widths of Lya and CIV and their ratio on one hand and the optical line parameters on the other. The UV and X-ray luminosities strongly correlate with the line widths of Hβand the Fe II/Hβ ratio. No significant correlation is found between the infrared-soft X-ray continuum slope αix and the line width of Hβ.

  17. Bayesian latent variable models for hierarchical clustered count outcomes with repeated measures in microbiome studies.

    Science.gov (United States)

    Xu, Lizhen; Paterson, Andrew D; Xu, Wei

    2017-04-01

    Motivated by the multivariate nature of microbiome data with hierarchical taxonomic clusters, counts that are often skewed and zero inflated, and repeated measures, we propose a Bayesian latent variable methodology to jointly model multiple operational taxonomic units within a single taxonomic cluster. This novel method can incorporate both negative binomial and zero-inflated negative binomial responses, and can account for serial and familial correlations. We develop a Markov chain Monte Carlo algorithm that is built on a data augmentation scheme using Pólya-Gamma random variables. Hierarchical centering and parameter expansion techniques are also used to improve the convergence of the Markov chain. We evaluate the performance of our proposed method through extensive simulations. We also apply our method to a human microbiome study.

  18. Clasp/SJ Observation of Time Variations of Lyman-Alpha Emissions in a Solar Active Region

    Science.gov (United States)

    Ishikawa, S.; Kubo, M.; Katsukawa, Y.; Kano, R.; Narukage, N.; Ishikawa, R.; Bando, T.; Winebarger, A.; Kobayashi, K.; Trujillo Bueno, J.; Auchere, F.

    2016-01-01

    The Chromospheric Lyman-alpha SpectroPolarimeter (CLASP) is a sounding rocket experiment launched on September 3, 2015 to investigate the solar chromosphere, and the slit-jaw (SJ) optical system took Lya images with the high time cadence of 0.6 s. By the CLASP/SJ observation, many time variations in the solar chromosphere with the time scale of time variations and relation to the coronal structure observed by SDO/AIA. We compared the Ly(alpha) time variations at footpoints of coronal magnetic fields observed by AIA 211 Å (approx.2 MK) and AIA 171 Å (0.6 MK), and non-loop regions. As the result, we found the time variations had more in the footpoint regions. On the other hand, the time variations had no dependency on the temperature of the loop.

  19. Detection of a Hot Binary Companion of $\\eta$ Carinae

    CERN Document Server

    Iping, R C; Gull, T R; Massa, D L; Hillier, D J; Iping, Rosina C.; Sonneborn, George; Gull, Theodore R.; Massa, Derck L.

    2005-01-01

    We report the detection of a hot companion of $\\eta$ Carinae using high resolution spectra (905 - 1180 \\AA) obtained with the Far Ultraviolet Spectroscopic Explorer (\\fuse) satellite. Observations were obtained at two epochs of the 2024-day orbit: 2003 June during ingress to the 2003.5 X-ray eclipse and 2004 April several months after egress. These data show that essentially all the far-UV flux from \\etacar shortward of \\lya disappeared at least two days before the start of the X-ray eclipse (2003 June 29), implying that the hot companion, \\etaB, was also eclipsed by the dense wind or extended atmosphere of \\etaA. Analysis of the far-UV spectrum shows that \\etaB is a luminous hot star. The \

  20. One-Loop Partition Functions in Deformed $\\mathcal{N}=4$ SYM Theory

    CERN Document Server

    Fokken, Jan

    2014-01-01

    We study the thermodynamic behaviour of the real $\\beta$- and $\\gamma_i$-deformation of $\\mathcal{N}=4$ Super Yang-Mills theory on $\\mathbb{R}\\times S^3$ in the planar limit. These theories were shown to be the most general asymptotically integrable supersymmetric and non-supersymmetric field-theory deformations of $\\mathcal{N}=4$ Super Yang-Mills theory, respectively. We calculate the first loop correction to their partition functions using an extension of the dilatation-operator and P\\'{o}lya-counting approach. In particular, we account for the one-loop finite-size effects which occur for operators of length one and two. Remarkably, we find that the $\\mathcal{O}(\\lambda)$ correction to the Hagedorn temperature is independent of the deformation parameters, although the partition function depends on them in a non-trivial way.

  1. Position-space renormalization-group approach to the resistance of random walks

    Science.gov (United States)

    Sahimi, Muhammad; Jerauld, Gary R.; Scriven, L. E.; Davis, H. Ted

    1984-06-01

    We consider a Pólya random walk, i.e., an unbiased, nearest-neighbor walk, on a d-dimensional hypercubic lattice and study the scaling behavior of the mean end-to-end resistance of the walk as a function of the number of steps in the walk. The resistance of the walk is generated by assigning a constant conductance to each step of the walk. This problem was recently proposed by Banavar, Harris, and Koplik, and may be useful for understanding the physics of disordered systems. We develop a position-space renormalization-group approach, a generalization of the one developed for percolation conductivity, and study the problem and a modification of it proposed here in one, two, and three dimensions. Our results are in good agreement with the numerical estimates of Banavar et al.

  2. The Golden-Thompson inequality: Historical aspects and random matrix applications

    Energy Technology Data Exchange (ETDEWEB)

    Forrester, Peter J., E-mail: p.forrester@ms.unimelb.edu.au; Thompson, Colin J. [Department of Mathematics and Statistics, The University of Melbourne, Victoria 3010 (Australia)

    2014-02-15

    The Golden-Thompson inequality, Tr (e{sup A+B}) ⩽ Tr (e{sup A}e{sup B}) for A, B Hermitian matrices, appeared in independent works by Golden and Thompson published in 1965. Both of these were motivated by considerations in statistical mechanics. In recent years the Golden-Thompson inequality has found applications to random matrix theory. In this article, we detail some historical aspects relating to Thompson's work, giving in particular a hitherto unpublished proof due to Dyson, and correspondence with Pólya. We show too how the 2 × 2 case relates to hyperbolic geometry, and how the original inequality holds true with the trace operation replaced by any unitarily invariant norm. In relation to the random matrix applications, we review its use in the derivation of concentration type lemmas for sums of random matrices due to Ahlswede-Winter, and Oliveira, generalizing various classical results.

  3. Detection of a white dwarf in a visual binary system

    Science.gov (United States)

    Boehm-Vitense, Erika

    1992-01-01

    The F6 giant HD 160365 was detected to have a white dwarf companion about 8 arcsec south of the star. The UV energy distribution observed with IUE shows that the white dwarf has an effective temperature of 23,000 +/- 2000 K. If log g = 8 the Lya profile indicates an effective temperature around 24,500 K. Using the theoretical models by Wesemael et al. (1980) one finds a visual magnitude of m(V) about 16.5. For T(eff) = 24,500 K one expects for a white dwarf a luminosity of log L/L(solar) about 1.3 and M(V) about 10.67. This gives a distance modulus for the system of m(V) - M(V) = 5.83 and an absolute magnitude M(V)= 0.3 for the giant.

  4. Lyapunov函数在一类二阶系统中的应用研究

    Institute of Scientific and Technical Information of China (English)

    李永福

    2013-01-01

    稳定性是一个系统正常运行的首要条件,设计和分析系统的一个关键就是对该系统进行判稳.Lyapunov稳定性理论对现代控制做出了贡献,而应用该理论时,一个关键问题就是构造Lyapunov函数.本文基于Lyapunov稳定定理,介绍了一种二阶系统的Lyapunov函数的构造方法,并列举了两个例子,通过实例证明了本文所提出的方法的有效性.

  5. Conference on Inequalities and Applications

    CERN Document Server

    Losonczi, László; Gilányi, Attila; Páles, Zsolt; Plum, Michael

    2009-01-01

    Inequalities continue to play an essential role in mathematics. Perhaps, they form the last field comprehended and used by mathematicians in all areas of the discipline. Since the seminal work Inequalities (1934) by Hardy, Littlewood and Pólya, mathematicians have laboured to extend and sharpen their classical inequalities. New inequalities are discovered every year, some for their intrinsic interest whilst others flow from results obtained in various branches of mathematics. The study of inequalities reflects the many and various aspects of mathematics. On one hand, there is the systematic search for the basic principles and the study of inequalities for their own sake. On the other hand, the subject is the source of ingenious ideas and methods that give rise to seemingly elementary but nevertheless serious and challenging problems. There are numerous applications in a wide variety of fields, from mathematical physics to biology and economics. This volume contains the contributions of the participants of th...

  6. Assessing the Exceptionality of Coloured Motifs in Networks

    Directory of Open Access Journals (Sweden)

    Lacroix Vincent

    2009-01-01

    Full Text Available Various methods have been recently employed to characterise the structure of biological networks. In particular, the concept of network motif and the related one of coloured motif have proven useful to model the notion of a functional/evolutionary building block. However, algorithms that enumerate all the motifs of a network may produce a very large output, and methods to decide which motifs should be selected for downstream analysis are needed. A widely used method is to assess if the motif is exceptional, that is, over- or under-represented with respect to a null hypothesis. Much effort has been put in the last thirty years to derive -values for the frequencies of topological motifs, that is, fixed subgraphs. They rely either on (compound Poisson and Gaussian approximations for the motif count distribution in Erdös-Rényi random graphs or on simulations in other models. We focus on a different definition of graph motifs that corresponds to coloured motifs. A coloured motif is a connected subgraph with fixed vertex colours but unspecified topology. Our work is the first analytical attempt to assess the exceptionality of coloured motifs in networks without any simulation. We first establish analytical formulae for the mean and the variance of the count of a coloured motif in an Erdös-Rényi random graph model. Using simulations under this model, we further show that a Pólya-Aeppli distribution better approximates the distribution of the motif count compared to Gaussian or Poisson distributions. The Pólya-Aeppli distribution, and more generally the compound Poisson distributions, are indeed well designed to model counts of clumping events. Altogether, these results enable to derive a -value for a coloured motif, without spending time on simulations.

  7. Radiation dose levels in pediatric chest CT: experience in 499 children evaluated with dual-source single-energy CT

    Energy Technology Data Exchange (ETDEWEB)

    Martine, Remy-Jardin; Colas, Lucie; Jean-Baptiste, Faivre; Remy, Jacques [CHU Lille (EA 2694) University of Lille, Department of Thoracic Imaging, Hospital Calmette, Lille (France); Santangelo, Teresa [CHU Lille (EA 2694) University of Lille, Department of Thoracic Imaging, Hospital Calmette, Lille (France); Bambino Gesu Children' s Hospital, Department of Imaging, Rome (Italy); Duhamel, Alain [University of Lille (EA 2694), Department of Biostatistics, CHU Lille, Lille (France); Deschildre, Antoine [CHU Lille - University of Lille, Department of Pediatric Pulmonology, Lille (France)

    2017-02-15

    The availability of dual-source technology has introduced the possibility of scanning children at lower kVp with a high-pitch mode, combining high-speed data acquisition and high temporal resolution. To establish the radiation dose levels of dual-source, single-energy chest CT examinations in children. We retrospectively recorded the dose-length product (DLP) of 499 consecutive examinations obtained in children <50 kg, divided into five weight groups: group 1 (<10 kg, n = 129); group 2 (10-20 kg, n = 176); group 3 (20-30 kg, n = 99), group 4 (30-40 kg, n = 58) and group 5 (40-49 kg, n = 37). All CT examinations were performed with high temporal resolution (75 ms), a high-pitch mode and a weight-adapted selection of the milliamperage. CT examinations were obtained at 80 kVp with a milliamperage ranging between 40 mAs and 90 mAs, and a pitch of 2.0 (n = 162; 32.5%) or 3.0 (n = 337; 67.5%). The mean duration of data acquisition was 522.8 ± 192.0 ms (interquartile range 390 to 610; median 490). In the study population, the mean CT dose index volume (CTDIvol{sub 32}) was 0.83 mGy (standard deviation [SD] 0.20 mGy; interquartile range 0.72 to 0.94; median 0.78); the mean DLP{sub 32} was 21.4 mGy.cm (SD 9.1 mGy.cm; interquartile range 15 to 25; median 19.0); and the mean size-specific dose estimate (SSDE) was 1.7 mGy (SD 0.4 mGy; interquartile range 1.5 to 1.9; median 1.7). The DLP{sub 32}, CTDI{sub vol32} and SSDE were found to be statistically significant in the five weight categories (P < 0.0001). This study establishes the radiation dose levels for dual-source, single-kVp chest CT from a single center. In the five weight categories, the median values varied 15-37 mGy.cm for the DLP{sub 32}, 0.78-1.25 mGy for the CTDI{sub vol32} and 1.6-2.1 mGy for the SSDE. (orig.)

  8. External dose reconstruction in tooth enamel of Techa riverside residents

    Energy Technology Data Exchange (ETDEWEB)

    Shishkina, E.A.; Volchkova, A.Yu.; Krivoschapov, V.A.; Degteva, M.O. [Urals Research Center for Radiation Medicine, Chelyabinsk (Russian Federation); Timofeev, Y.S.; Zalyapin, V.I. [Southern Urals State University, Chelyabinsk (Russian Federation); Fattibene, P.; Della Monaca, S.; De Coste, V. [Istituto Superiore di Sanita e Istituto Nazionale di Fisica Nucleare, Rome (Italy); Wieser, A. [Helmholtz Zentrum Muenchen, German Research Centre for Environmental Health, Neuherberg (Germany); Ivanov, D.V. [M.N. Mikheev Institute of Metal Physics, Ural Division of the Russian Academy of Sciences, Ekaterinburg (Russian Federation); Ural Federal University, Yekaterinburg (Russian Federation); Anspaugh, L.R. [University of Utah, Salt Lake City, UT (United States)

    2016-11-15

    This study summarizes the 20-year efforts for dose reconstruction in tooth enamel of the Techa riverside residents exposed to ionizing radiation as a result of radionuclide releases into the river in 1949-1956. It represents the first combined analysis of all the data available on EPR dosimetry with teeth of permanent residents of the Techa riverside territory. Results of electron paramagnetic resonance (EPR) measurements of 302 teeth donated by 173 individuals living permanently in Techa riverside settlements over the period of 1950-1952 were analyzed. These people were residents of villages located at the free-flowing river stream or at the banks of stagnant reservoirs such as ponds or blind river forks. Cumulative absorbed doses measured using EPR are from several sources of exposure, viz., background radiation, internal exposure due to bone-seeking radionuclides ({sup 89}Sr, {sup 90}Sr/{sup 90}Y), internal exposure due to {sup 137}Cs/{sup 137m}Ba incorporated in soft tissues, and anthropogenic external exposure. The purpose of the present study was to evaluate the contribution of different sources of enamel exposure and to deduce external doses to be used for validation of the Techa River Dosimetry System (TRDS). Since various EPR methods were used, harmonization of these methods was critical. Overall, the mean cumulative background dose was found to be 63 ± 47 mGy; cumulative internal doses due to {sup 89}Sr and {sup 90}Sr/{sup 90}Y were within the range of 10-110 mGy; cumulative internal doses due to {sup 137}Cs/{sup 137m}Ba depend on the distance from the site of releases and varied from 1 mGy up to 90 mGy; mean external doses were maximum for settlements located at the banks of stagnant reservoirs (∝500 mGy); in contrast, external doses for settlements located along the free-flowing river stream did not exceed 160 mGy and decreased downstream with increasing distance from the site of release. External enamel doses calculated using the TRDS code and

  9. Doses metrics and patient age in CT.

    Science.gov (United States)

    Huda, Walter; Tipnis, Sameer V

    2016-03-01

    The aim of this study was to investigate how effective dose and size-specific dose estimate (SSDE) change with patient age (size) for routine head and abdominal/pelvic CT examinations. Heads and abdomens of patients were modelled as a mass-equivalent cylinder of water corresponding to the patient 'effective diameter'. Head CT scans were performed at CTDIvol(S) of 40 mGy, and abdominal CT scans were performed at CTDIvol(L) of 10 mGy. Values of SSDE were obtained using conversion factors in AAPM Task Group Report 204. Age-specific scan lengths for head and abdominal CT scans obtained from the authors' clinical practice were used to estimate the dose-length product for each CT examination. Effective doses were calculated from previously published age- and sex-specific E/DLP conversion factors, based on ICRP 103 organ-weighting factors. For head CT examinations, the scan length increased from 15 cm in a newborn to 20 cm in adults, and for an abdominal/pelvic CT, the scan length increased from 20 cm in a newborn to 45 cm in adults. For head CT scans, SSDE ranged from 37.2 mGy in adults to 48.8 mGy in a newborn, an increase of 31 %. The corresponding head CT effective doses range from 1.4 mSv in adults to 5.2 mSv in a newborn, an increase of 270 %. For abdomen CT scans, SSDE ranged from 13.7 mGy in adults to 23.0 mGy in a newborn, an increase of 68 %. The corresponding abdominal CT effective doses ranged from 6.3 mSv in adults to 15.4 mSv in a newborn, an increase of 140 %. SSDE increases much less than effective dose in paediatric patients compared with adults because it does not account for scan length or scattered radiation. Size- and age-specific effective doses better quantify the total radiation received by patients in CT by explicitly accounting for all organ doses, as well as their relative radio sensitivity.

  10. STUDY OF THE SEDIMENTATION TREND IN THE PROSPECTIVE AREA OF PORT OF MARINE CENTER, CIREBON BASED ON REMOTE SENSING DATA

    Directory of Open Access Journals (Sweden)

    Undang Hernawan

    2017-07-01

    Full Text Available A coastal zone is the interface between the land and water that influenced by both of them. Coastal dynamic is influenced by many factors from land and sea, such as sedimentation and current. In order to support marine facility, Marine Geological Institute of Indonesia (MGI plan to build a port. The prospective area is behind MGI office at Cirebon. This study use multi temporal remote sensing data in order to observe trend of coastline change around MGI. Based on the interpretation of the data, there are sedimentation around the MGI water and abrasion due to the presence of Kejawanan’s jetty and Kalijaga River. The result also shows that the current in this region is moving from southeast to northwest. The presence of the Kejawanan’s jetty stymies the movement of sediment. The sediment which is normally moving to the north of the jetty is then trapped on the south side of the structure, so that the sediment precipitates in this region and makes it as the active region of sedimentation and accretion. The presence mangrove conduces to support sedimentation speed and accretion at this region, because of his function as the catchment area. Abrasion occurs in the eastern part of MGI office at the Kalijaga river mouth within the bay. The Kalijaga River mouth is predicted to be the primary source of sedimentation in this area. The coastline change caused by sedimentation will be continuing as long as it is supplied by the sediment. The direction of the sedimentation is parallel to the jetty and it forms ellipsoid, with the sedimentation/accretion region is behind MGI office. The abrasion area is found in Kalijaga River mouth and a small area beside Kalijaga River. In order to build a port, we have to consider this sedimentation process. One of the alternatives to build the port is to make a quay pile model which gives way the current to pass through the other side of the port. Another alternative is to build the port as a pond model but

  11. Development of CT scanner models for patient organ dose calculations using Monte Carlo methods

    Science.gov (United States)

    Gu, Jianwei

    There is a serious and growing concern about the CT dose delivered by diagnostic CT examinations or image-guided radiation therapy imaging procedures. To better understand and to accurately quantify radiation dose due to CT imaging, Monte Carlo based CT scanner models are needed. This dissertation describes the development, validation, and application of detailed CT scanner models including a GE LightSpeed 16 MDCT scanner and two image guided radiation therapy (IGRT) cone beam CT (CBCT) scanners, kV CBCT and MV CBCT. The modeling process considered the energy spectrum, beam geometry and movement, and bowtie filter (BTF). The methodology of validating the scanner models using reported CTDI values was also developed and implemented. Finally, the organ doses to different patients undergoing CT scan were obtained by integrating the CT scanner models with anatomically-realistic patient phantoms. The tube current modulation (TCM) technique was also investigated for dose reduction. It was found that for RPI-AM, thyroid, kidneys and thymus received largest dose of 13.05, 11.41 and 11.56 mGy/100 mAs from chest scan, abdomen-pelvis scan and CAP scan, respectively using 120 kVp protocols. For RPI-AF, thymus, small intestine and kidneys received largest dose of 10.28, 12.08 and 11.35 mGy/100 mAs from chest scan, abdomen-pelvis scan and CAP scan, respectively using 120 kVp protocols. The dose to the fetus of the 3 month pregnant patient phantom was 0.13 mGy/100 mAs and 0.57 mGy/100 mAs from the chest and kidney scan, respectively. For the chest scan of the 6 month patient phantom and the 9 month patient phantom, the fetal doses were 0.21 mGy/100 mAs and 0.26 mGy/100 mAs, respectively. For MDCT with TCM schemas, the fetal dose can be reduced with 14%-25%. To demonstrate the applicability of the method proposed in this dissertation for modeling the CT scanner, additional MDCT scanner was modeled and validated by using the measured CTDI values. These results demonstrated that the

  12. Adaptive statistical iterative reconstruction: reducing dose while preserving image quality in the pediatric head CT examination

    Energy Technology Data Exchange (ETDEWEB)

    McKnight, Colin D.; Watcharotone, Kuanwong; Ibrahim, Mohannad; Christodoulou, Emmanuel; Baer, Aaron H.; Parmar, Hemant A. [University of Michigan, Department of Radiology, Ann Arbor, MI (United States)

    2014-08-15

    Over the last decade there has been escalating concern regarding the increasing radiation exposure stemming from CT exams, particularly in children. Adaptive statistical iterative reconstruction (ASIR) is a relatively new and promising tool to reduce radiation dose while preserving image quality. While encouraging results have been found in adult head and chest and body imaging, validation of this technique in pediatric population is limited. The objective of our study was to retrospectively compare the image quality and radiation dose of pediatric head CT examinations obtained with ASIR compared to pediatric head CT examinations without ASIR in a large patient population. Retrospective analysis was performed on 82 pediatric head CT examinations. This group included 33 pediatric head CT examinations obtained with ASIR and 49 pediatric head CT examinations without ASIR. Computed tomography dose index (CTDI{sub vol}) was recorded on all examinations. Quantitative analysis consisted of standardized measurement of attenuation and the standard deviation at the bilateral centrum semiovale and cerebellar white matter to evaluate objective noise. Qualitative analysis consisted of independent assessment by two radiologists in a blinded manner of gray-white differentiation, sharpness and overall diagnostic quality. The average CTDI{sub vol} value of the ASIR group was 21.8 mGy (SD = 4.0) while the average CTDI{sub vol} for the non-ASIR group was 29.7 mGy (SD = 13.8), reflecting a statistically significant reduction in CTDI{sub vol} in the ASIR group (P < 0.01). There were statistically significant reductions in CTDI for the 3- to 12-year-old ASIR group as compared to the 3- to 12-year-old non-ASIR group (21.5 mGy vs. 30.0 mGy; P = 0.004) as well as statistically significant reductions in CTDI for the >12-year-old ASIR group as compared to the >12-year-old non-ASIR group (29.7 mGy vs. 49.9 mGy; P = 0.0002). Quantitative analysis revealed no significant difference in the

  13. Scintillation and storage luminescence properties of MgF2 transparent ceramics doped with Ce3+

    Science.gov (United States)

    Nakamura, Fumiya; Kato, Takumi; Okada, Go; Kawaguchi, Noriaki; Fukuda, Kentaro; Yanagida, Takayuki

    2017-10-01

    In this paper, we report basic optical properties and scintillation and storage luminescence properties of MgF2:Ce transparent ceramics with different doping concentrations of Ce (0.01, 0.1 and 1%) synthesized by spark plasma sintering (SPS). In scintillation, thermally-stimulated luminescence (TSL) and optically-stimulated luminescence (OSL), the dominant emissions were due to the 5d-4f transitions of Ce3+ which appeared in the near-UV region peaking around 320 and 360 nm. The scintillation was evaluated by X-ray irradiation while OSL was observed under 540 nm stimulation. In particular, the TSL sensitivity was high and showed a good linearity from 0.1 mGy to 1000 mGy.

  14. Application of TL dosemeters for dose distribution measurements at high temperatures in nuclear reactors.

    Science.gov (United States)

    Osvay, M; Deme, S

    2006-01-01

    Al2O3:Mg,Y ceramic thermoluminescence dosemeters were developed at the Institute of Isotopes for high dose applications at room temperatures. The glow curve of Al2O3:Mg,Y exhibits two peaks--one at 250 degrees C (I) and another peak at approximately 400 degrees C (II). In order to extend the application of these dosemeters to high temperatures, the effect of irradiation temperature was investigated using temperature controlled heating system during high dose irradiation at various temperatures (20-100 degrees C). The new calibration and measuring method has been successfully applied for dose mapping within the hermetic zone of the Paks Nuclear Power Plant even at high temperature parts of blocks.

  15. The effect of electron irradiation on the structure and iron speciation in sodium aluminum (iron) phosphate glasses

    Science.gov (United States)

    Stefanovsky, S. V.; Presniakov, I. A.; Sobolev, A. V.; Glazkova, I. S.; Kadyko, M. I.; Stefanovsky, O. I.

    2016-08-01

    The effect of 8 MeV electron irradiation on the structure of glasses in the series 40 Na2O, (20-x) Al2O3, x Fe2O3, 40 P2O5 (mol.%) and on the iron speciation in these samples was studied by FTIR and Mössbauer spectroscopic techniques. Irradiation up to a dose of 1.0 MGy has no appreciable effects on the character of the bonds within anionic motif of the glass network. Electron irradiation increases the fraction of aluminum in octahedral coordination. Iron in both unirradiated and irradiated glasses is present mainly as Fe(III) (60-75% of the total amount) in the glasses and partly as Fe(II) and the ratio of two forms remains constant up to a dose of 1.0 MGy.

  16. Dose evaluation in diagnostic for computerized tomography; Evaluacion de dosis en diagnostico por tomografia computarizada

    Energy Technology Data Exchange (ETDEWEB)

    Flores, W.; Borges, J.C.; Mota, H. [Universidad Federal de Rio de Janeiro, PEN/COPPE/UFRJ. Caixa Postal 68509. 21945-970 Rio de Janeiro (Brazil)

    1998-12-31

    The patients which are subjected to computerized tomography tests are exposed to relatively high doses given as result doses on organs that are not matter to test. It was realized a dose levels raising in patients subjected to tests by T C, utilizing to measure this magnitude, TLD-100 thermoluminescent dosemeters which were put directly on the patient, in eye regions, thyroid, breast and navel; founding doses fluctuating between 29.10-49.39 mGy in organs examined and dose values between 0.21-29.10 mGy for organs that no matter to test. The applications of ionizing radiations in medicine do not have dose limits, but paying attention to the radiological protection optimization principle, it is recommended the use of clothes to anti-rays protection for zones not examined, getting with this to reduce the level doses as low as possible, without this to diminish the test quality. (Author)

  17. Dosimetric properties of natural quartz grains extracted from fired materials

    DEFF Research Database (Denmark)

    Bluszcz, A.; Bøtter-Jensen, L.

    1995-01-01

    The paper describes an examination of the dosimetric properties of natural quartz grains extracted from ancient fired materials. Eleven samples of different origin were tested for their TL and GLSL (green light stimulated luminescence) sensitivities within the mGy dose range. Very promising results...... were obtained showing the possibility of measuring the doses of around 10 mGy with 1% precision using GLSL or TL and using the single aliquot technique for natural quartz as a dosimeter. The lowest detectable dose was estimated to be lower than 500 mu Gy. The results obtained indicate that natural...... quartz grains from selected materials could be used for the dosimetry of environmental gamma radiation for the purposes of paleodosimetric dating methods as well as for accident dosimetry....

  18. Estimation of MSAD values in computed tomography scans using radiochromic films

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Bruno Beraldo; Teogenes Augusto da, E-mail: bbo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Mourao, Arnaldo Prata [Centro Federal de Educacao Tecnologica de Minas Gerais (CEFET-MG), Belo Horizonte, MG (Brazil)

    2013-03-15

    Objective: To evaluate the feasibility of using radiochromic films as an alternative dosimeter to estimate the multiple scan average dose on the basis on kerma profiles. Materials and Methods: The radiochromic films were distributed in cylinders positioned in the center and in four peripheral bores of a standard abdominal phantom utilized for computed tomography dosimetry. Results: Values for multiple scan average dose values corresponded to 13.6 {+-} 0.7, 13.5 {+-} 0.7 and 18.7 {+-} 1.0 mGy for pitch of 0.75, 1.00 and 1.50, respectively. Conclusion: In spite of results showing lower values than the reference level for radiodiagnosis (25 mGy) established by the Brazilian regulations for abdominal studies, it is suggested that there is room to optimize procedures and review the reference level for radiodiagnosis in Brazil. (author)

  19. Mechanical strength of low-tempepvature-irradiated polyimides: A five-to-tenfold improvement in dose-resistance over epoxies

    Science.gov (United States)

    Coltman, R. R.; Klabunde, C. E.

    Neutronics calculations by Engholm [1] show that without additional shielding even the first fusion test reactors such as the Fusion Engineering Device may produce lifetime doses at magnet insulator locations that exceed the radiation tolerance of glass-fabric-filled (gff) epoxies now used. To explore the possible use of an alternative insulator, the mechanical strength of pure and recently available gff polyimides was studied as a function of gamma-ray irradiation at 4.9 K to 100 MGy (10 10 rads). After a postirradiation anneal at 307 K the flexure and compressive strengths of the gff materials measured at 77 K were reduced by up to 40% for 100 MGy while the pure material changed little. Testing done at 300 K gave similar results, but all stress values were about 40% less. Compared to earlier epoxy studies [2] we find that, overall, the gff polyimides are 5 to 10 times more radiation resistant than comparably prepared gff epoxies.

  20. Discusión de las aproximaciones utilizadas en el estudio de la recombinación dielectrónica de los metales en envolturas estelares

    Science.gov (United States)

    Cruzado, A.; di Rocco, H. O.; Ringuelet, A.

    Se calcularon nuevos parámetros atómicos del MgI reemplazando los niveles de energía teóricos por los observados. Con ellos se calculó nuevamente el flujo originado en la Recombinación Dielectrónica (RD) del MgII y se comparó con resultados anteriores. Se evaluó también la posible influencia de diferentes fuentes de opacidad, en el flujo originado en la RD de los metales en atmósferas extendidas de estrellas tempranas. En particular, se calculó la profundidad óptica de las líneas de MgI para diferentes condiciones físicas del medio.

  1. Studies of some isomeric yield ratios produced with bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Kolev, Dimitar

    1998-05-11

    The experimental isomeric ratios for {sup 52m,g}Mn, {sup 86m,g}Y, {sup 87m,g}Y, {sup 89m,g}Zr, {sup 110m,g}In, {sup 111m,g}In, {sup 112m,g}In, {sup 152m1,g}Pm, {sup 152m2,m1}Eu, {sup 162m,g}Ho, {sup 164m,g}Ho and {sup 178m,g}Lu measured by the activation technique from different targets in ({gamma}, xnp) reactions (x{<=}3) at the bremsstrahlung end-point energy of 43 MeV are presented. The predictions of calculations performed by means of compound nucleus particle evaporation and final {gamma}-deexcitation were critically discussed. The importance of inclusion in the calculations of nonequilibrium particle emission and an adequate {gamma}-decay mode of isomeric nuclei was considered for some of the reactions investigated.

  2. Report on results of seventeen years in consultations of radiation exposed pregnant women. Bericht ueber 17jaehrige Erfahrungen bei der Beratung strahlenbelasteter Schwangerer

    Energy Technology Data Exchange (ETDEWEB)

    Bruening, L. (Bundesgesundheitsamt, Berlin (Germany). Klinisch-Diagnostischer Bereich); Arndt, D. (Bundesgesundheitsamt, Berlin (Germany). Klinisch-Diagnostischer Bereich); Laude, G. (Bundesgesundheitsamt, Berlin (Germany). Klinisch-Diagnostischer Bereich)

    1992-06-01

    In a survey it will be given results of consultations of pregnant women exposed during the pregnancy in the period of 1976 to 1992 formerly in the National Board of Atomic Safety and Radiation Protection of the GDR and since 1990 in the Clinic-diagnostical Division of the Federal Health Office. The report includes dose estimations of the embryo and medical assessments of 430 pregnant women. The radiation exposure were mainly received by X-ray diagnostic (n = 406 cases) and the others by applications of radiation in nuclear medicine, research and vocational training (n = 24 cases). Results of dose and risk estimation were summarized in tables. Women having incurred fetal doses in excess of 100 mGy were recommended to interrupt pregnancy. A fetal dose above 100 mGy occured in 9 cases. The anatomico-pathological and embryological findings of the embryo or fetus showed only in one case a reference of teratogenic radiation damage. (orig.)

  3. Medical-biological aspects of radiation effects in Daphnia magna

    Science.gov (United States)

    Sarapultseva, E.; Uskalova, D.; Savina, N.; Ustenko, K.

    2017-01-01

    We have shown that γ-irradiation at doses of 100 and 1000 mGy significantly compromised fecundity and reproductive success of the directly exposed D. magna. These effects were also observed among the non-exposed first-generation progeny of irradiated parents, thus implying the manifestation of transgenerational effects in Daphnia. We have also shown that compromised viability of irradiated D. magna can be attributed cytotoxic effects of irradiation. It would therefore appear that the compromised viability may be attributed to the cytotoxic effects resulted from epigenetic changes affecting some metabolic pathways involved in detoxification of free-radicals. Additionally we have analyzed more distant progeny of irradiated at doses of 10, 100 and 1000 mGy Daphnia. Our data demonstrated that multicellular crustacean D. magna represent a very useful experimental model for analyse of long-term effects of ionising radiation at the organismal level.

  4. Multislice spiral CT of the paranasal sinuses; Mehrschicht-Spiral-CT der Nasennebenhoehlen: Erste Erfahrungen unter besonderer Beruecksichtigung der Strahlenexposition

    Energy Technology Data Exchange (ETDEWEB)

    Dammann, F.; Bode, A.; Heuschmid, M.; Kopp, A.; Georg, C.; Pereira, P.L.; Claussen, C.D. [Tuebingen Univ. (Germany). Radiologische Universitaetsklinik

    2000-08-01

    Purpose: To evaluate the potential of multislice CT in the diagnosis of the paranasal sinuses. Methods: Dose measurements were performed exposing an Alderson Rando phantom in a four-slice spiral CT (MS-CT) while applying a variety of scan parameters. Additionally, 30 consecutive patients underwent a transversal examination by the MS-CT using 1/1/3.5/0.5 mm spiral parameters and an additional transversal or coronal scan on a conventional single slice spiral CT (SS-CT) with 2/3/1 mm. Coronal reformations of the MS-CT were compared with the primary coronal SS-CT, or coronal reformations of the transversal SS-CT, respectively, with regard to image quality and depiction of relevant anatomical details of the region. Results: Superficial exposure values at the level of the eye lenses as well as for the thyroid gland were superior for MS-CT (3.62 mGy, and 0.12 mGy, resp.) as compared to SS-CT (2.96 mGy, and 0.07 mGy). Image quality was equal or superior for MS-CT as compared to SS-CT in all but one case. Drawbacks of SS-CT, such as dental amalgam artifacts, stair step artifacts or partial volume artifacts did not notably affect the coronal reformations of MS-CT. Conclusions: MS-CT seems to have the potential to replace primary coronal CT of the paranasal sinuses without any loss of image quality, but may even improve the overall diagnostic value. Radiation doses may still have to be reduced. (orig.) [German] Ziel: Erprobung eines Multislice-CT (MS-CT) zur Diagnostik der Nasennebenhoehlen (NNH). Methode: An einem Alderson Rando Phantom wurden Dosismessungen bei der Spiral-CT der NNH mit einem Mehrschicht-CT (MS-CT) unter Verwendung unterschiedlicher Scanparameter durchgefuehrt. Anschliessend wurden 30 konsekutive Patienten an dem MS-CT mit den Spiralparametern 1/1/3,5/0,5 mm und einem konventionellen Einzeilen Spiral-CT (SS-CT; 2/3/1 mm) untersucht. Die koronaren Rekonstruktionen der transversalen MS-CT wurden mit den koronaren Rekonstruktionen bzw. den primaeren koronaren

  5. EPR tooth dosimetry of SNTS area inhabitants

    Energy Technology Data Exchange (ETDEWEB)

    Sholom, Sergey [Scientific Center for Radiation Medicine, Melnikova str., 53, Kiev (Ukraine); Desrosiers, Marc [Ionizing Radiation Division, National Institute of Standards and Technology, Gaithersburg, MD (United States); Bouville, Andre; Luckyanov, Nicholas [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 6120 Executive Boulevard, Bethesda, MD (United States); Chumak, Vadim [Scientific Center for Radiation Medicine, Melnikova str., 53, Kiev (Ukraine); Simon, Steven L. [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 6120 Executive Boulevard, Bethesda, MD (United States)], E-mail: ssimon@mail.nih.gov

    2007-07-15

    The determination of external dose to teeth of inhabitants of settlements near the Semipalatinsk Nuclear Test Site (SNTS) was conducted using the EPR dosimetry technique to assess radiation doses associated with exposure to radioactive fallout from the test site. In this study, tooth doses have been reconstructed for 103 persons with all studied teeth having been formed before the first nuclear test in 1949. Doses above those received from natural background radiation, termed 'accident doses', were found to lie in the range from zero to approximately 2 Gy, with one exception, a dose for one person from Semipalatinsk city was approximately 9 Gy. The variability of reconstructed doses within each of the settlements demonstrated heterogeneity of the deposited fallout as well as variations in lifestyle. The village mean external gamma doses for residents of nine settlements were in the range from a few tens of mGy to approximately 100 mGy.

  6. Shielding property of different prosthetic materials to shield radiation of 125I seed%基托材料对125I粒子屏蔽效果的初步研究

    Institute of Scientific and Technical Information of China (English)

    白阳; 王燕一; 张蕾; 步荣发

    2011-01-01

    目的 探讨应用赝复体或修复体承载 125I粒子进行肿瘤治疗时,不同修复材料对 125I粒子辐射的屏蔽作用.方法 125I粒子为放射源,用热释光剂量元件进行测量,建立体外照射模型.载体选用纯钛板、钴铬合金板、聚甲基丙烯酸甲酯板,以铅板为对照,比较各种材料板的屏蔽效果.结果 在距离放射源10 mm处,经屏蔽后剂量分别为0.09 mm纯钛板2.805 mGy,0.48 mm钛板1.082 mGy,0.410、0.671 mm钴铬合金板为0.390、0.261 mGy,1.685 mm聚甲基丙烯酸甲酯板为2.885 mGy.结论 钴铬合金的屏蔽效果优于其他材料,聚甲基丙烯酸甲酯对 125I粒子具有一定屏蔽作用,与0.557 mm以上钛板共用可达到铅板防护效果.%Objective To investigation the shielding property to 125I of several different prosthetic materials used in clinical when prostheses are used as carriers of 125I seed in tumor treatment. Methods125I seeds were taken as the radiation sources to establish a model in vitro and the radiation doses were measured by thermoluminescent dosemeters(TLD). The shielding property of titanium plate, cochrome plate, and poly methyl methacrylate(PMMA) plate were detected, calculated and compared with that of plumbum plate in the control group. Results The radiation doses of the radiation source at 10 mm distance through the following materials were measured, and the results are 2.805 mGy (0.09 mm thick titanium plate), 1.082 mGy (0.48 thick titanium plate),0.390 mGy (0.41 mm thick cochrome plate), and 0.261 mGy (0.67 mm′s cochrome plate), and 2.885 mGy (1.685 mm thick PMMA plate). ConclusionsThe shield property of cochrome is optimal. The poly methyl methacrylate behaves to some extend as a shield to the 125I seed which can shield the radiation as the effects of plumbum when adopted together with the 0.557 mm′s(or more)titanium plate.

  7. Production of dodecanedioic acid from n-dodecane by yeasts.

    Science.gov (United States)

    Liu, W H; Kuo, C K

    1989-11-01

    In order to develop a process for production of dodecanedioic acid (DC-12) as starting materials for the chemical industry, a n-dodecane assimilating and DC-12-producing yeast was isolated from Taiwan soil. The taxonomical characteristics of this newly isolated yeast were examined and it was identified as Candida tropicalis NTU-512. The newly isolated strain was improved successively by NTG mutagenesis. A high potency DC-12-producing mutant 91 which showed slight growth both in DC-12 and n-dodecane enrichment media was isolated. The DC-12 productivity of mutant 91 reached 3,326 mg/I by shaking culture at 30 degrees C for 72 h. This figure is 2.5-fold that of the parent strain (1,310 mg/I).

  8. Reduction of radiation dose by using digital luminescence radiography compared to conventional screen film system with grid cassette; Reduktion der Strahlendosis mittels Speicherfolienradiographie im Vergleich zum konventionellen Film-Folien-System mit Rasterkassette am Schaedelphantom

    Energy Technology Data Exchange (ETDEWEB)

    Heyne, J.P.; Merbold, H.; Neumann, R.; Freesmeyer, M.; Jonetz-Mentzel, L.; Kaiser, W.A. [Friedrich-Schiller-Univ. Jena, Inst. fuer Diagnostische und Interventionelle Radiologie (Germany); Sehner, J. [AGFA-Deutschland, Vertriebsgesellschaft (Germany)

    1999-07-01

    Purpose: How much can the radiation dose be reduced for skull radiography by using digital luminescence radiography (DLR) compared to a conventional screen film system with a grid cassette? Methods and Materials: A skull phantom (3M) was X-rayed in anterior-posterior orientation using both a conventional screen film system with grid cassette and DLR (ADC-70, Agfa). The tube current time product (mAs) was diminished gradually while keeping the voltage constant. The surface entrance dose was measured by a sensor of Dosimax (Wellhoefer). Five investigators evaluated the images by characteristic and critical features, spatial resolution and contrast. Results: The surface entrance dose at 73 kV/22 mAs was 0,432 mGy in conventional screen film system and 0,435 mGy in DLR. The images could be evaluated very well down to an average dose of 71% (0,308 mGy; SD 0,050); sufficient images were obtained down to an average dose of 31% (0,136 mGy; SD 0,065). The resolution of the line pairs were reduced down to a 2 levels depending on the investigator. Contrast was assessed as being very good to sufficient. The acceptance of the postprocessed images (MUSICA-software) was individually different and resultde in an improvement of the assessment of bone structures an contrast in higher dose ranges only. Conclusion: For the sufficient assessment of a possible fracture/of paranasal sinuses/of measurement the skull the dose can be reduced to at least 56% (31%; SD 14,9%)/40% (27%; SD 9,3%)/18% (14%; SD 4,4%). Digital radiography allows question-referred exposure parameters with clearly reduced dose, so e.g. for fracture exclusion 73 kV/12,5 mAs and to skull measurement 73 kV/4 mAs. (orig.) [Deutsch] Ziel: Wie weit kann unter Einsatz der rasterlosen Speicherfolienradiographie bei einer Schaedelaufnahme die Strahlendosis im Vergleich zum Film-Folien-System (FFS) mit Rasterkassette (RK) fragestellungsbezogen gesenkt werden? Material und Methode: Ein Schaedelphantom (3M) wurde konventionell

  9. Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Hollmann, E. M.; Moyer, R. A. [University of California-San Diego, La Jolla, California 92093 (United States); Commaux, N.; Shiraki, D. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Eidietis, N. W.; Parks, P. B. [General Atomics, San Diego, California 92186 (United States); Lasnier, C. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2015-10-15

    Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma edge magnetic perturbation is seen to lock to a preferential phase during the VDE thermal quench, but this phase is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Clear indications of plasma infra-red (IR) emission are observed both before and during the disruptions. This IR emission can affect calculation of disruption heat loads; here, the time decay of post-disruption IR signals is used to correct for this effect.

  10. Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

    Science.gov (United States)

    Hollmann, E. M.; Commaux, N.; Eidietis, N. W.; Lasnier, C. J.; Moyer, R. A.; Parks, P. B.; Shiraki, D.

    2015-10-01

    Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma edge magnetic perturbation is seen to lock to a preferential phase during the VDE thermal quench, but this phase is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Clear indications of plasma infra-red (IR) emission are observed both before and during the disruptions. This IR emission can affect calculation of disruption heat loads; here, the time decay of post-disruption IR signals is used to correct for this effect.

  11. Enhancement of runaway production by resonant magnetic perturbation on J-TEXT

    Science.gov (United States)

    Chen, Z. Y.; Huang, D. W.; Izzo, V. A.; Tong, R. H.; Jiang, Z. H.; Hu, Q. M.; Wei, Y. N.; Yan, W.; Rao, B.; Wang, S. Y.; Ma, T. K.; Li, S. C.; Yang, Z. J.; Ding, D. H.; Wang, Z. J.; Zhang, M.; Zhuang, G.; Pan, Y.; J-TEXT Team

    2016-07-01

    The suppression of runaways following disruptions is key for the safe operation of ITER. The massive gas injection (MGI) has been developed to mitigate heat loads, electromagnetic forces and runaway electrons (REs) during disruptions. However, MGI may not completely prevent the generation of REs during disruptions on ITER. Resonant magnetic perturbation (RMP) has been applied to suppress runaway generation during disruptions on several machines. It was found that strong RMP results in the enhancement of runaway production instead of runaway suppression on J-TEXT. The runaway current was about 50% pre-disruption plasma current in argon induced reference disruptions. With moderate RMP, the runway current decreased to below 30% pre-disruption plasma current. The runaway current plateaus reach 80% of the pre-disruptive current when strong RMP was applied. Strong RMP may induce large size magnetic islands that could confine more runaway seed during disruptions. This has important implications for runaway suppression on large machines.

  12. Estimation of eye absorbed doses in head & neck radiotherapy practices using thermoluminescent detectors

    Directory of Open Access Journals (Sweden)

    Gh Bagheri

    2011-09-01

    Full Text Available  Determination of eye absorbed dose during head & neck radiotherapy is essential to estimate the risk of cataract. Dose measurements were made in 20 head & neck cancer patients undergoing 60Co radiotherapy using LiF(MCP thermoluminescent dosimeters. Head & neck cancer radiotherapy was delivered by fields using SAD & SSD techniques. For each patient, 3 TLD chips were placed on each eye. Head & neck dose was about 700-6000 cGy in 8-28 equal fractions. The range of eye dose is estimated to be (3.49-639.1 mGy with a mean of maximum dose (98.114 mGy, which is about 3 % of head & neck dose. Maximum eye dose was observed for distsnces of about 3 cm from edge of the field to eye.

  13. Design and Radiation Assessment of Optoelectronic Transceiver Circuits for ITER

    CERN Document Server

    Leroux, P; Van Uffelen, M; Steyaert, M

    2008-01-01

    The presented work describes the design and characterization results of different electronic building blocks for a MGy gamma radiation tolerant optoelectronic transceiver aiming at ITER applications. The circuits are implemented using the 70GHz fT SiGe HBT in a 0.35μm BiCMOS technology. A VCSEL driver circuit has been designed and measured up to a TID of 1.6 MGy and up to a bit rate of 622Mbps. No significant degradation is seen in the eye opening of the output signal. On the receiver side, both a 1GHz, 3kΩ transimpedance and a 5GHz Cherry-Hooper amplifier with over 20dB voltage gain have been designed.

  14. Unintentional exposure to radiation during pregnancy from nuclear medical diagnostic procedures; Unabsichtliche Strahlenexposition in der Schwangerschaft durch nuklearmedizinische Diagnostik

    Energy Technology Data Exchange (ETDEWEB)

    Moka, D. [Gemeinschaftspraxis fuer Radiologie und Nuklearmedizin, Essen (Germany)

    2005-12-01

    The administration of radiopharmaceuticals during pregnancy is contraindicated due to a lack of vital indications. However, if prenatal exposure to radiation should occur in the framework of a nuclear medical diagnostic procedure then fortunately no longterm side-effects would normally be expected. Radiation damage in the preimplantation phase leads to early abortion. However, if the further course of pregnancy remains uncomplicated then no subsequent side-effects need be expected. On a conservative estimate, it would require doses exceeding 50 mGy to cause radiation damage within the uterus after the preimplantation phase. However, the standard radioactivities applied for diagnostic purposes in nuclear medicine, can be obtained with doses of less than 20 mGy. On the basis of current knowledge, therefore, there is no reason to terminate pregnancy on medical grounds after diagnostic exposure to radiopharmaceuticals. (orig.)

  15. Survey of mammography practice in Croatia: equipment performance, image quality and dose.

    Science.gov (United States)

    Faj, Dario; Posedel, Dario; Stimac, Damir; Ivezic, Zdravko; Kasabasic, Mladen; Ivkovic, Ana; Kubelka, Dragan; Ilakovac, Vesna; Brnic, Zoran; Bjelac, Olivera Ciraj

    2008-01-01

    A national audit of mammography equipment performance, image quality and dose has been conducted in Croatia. Film-processing parameters, optical density (OD), average glandular dose (AGD) to the standard breast, viewing conditions and image quality were examined using TOR(MAM) test object. Average film gradient ranged from 2.6 to 3.7, with a mean of 3.1. Tube voltage used for imaging of the standard 45 mm polymethylmethacrylate phantom ranged from 24 to 34 kV, and OD ranged from 0.75 to 1.94 with a mean of 1.26. AGD to the standard breast ranged from 0.4 to 2.3 mGy with a mean of 1.1 mGy. Besides clinical conditions, the authors have imaged the standard phantom in the referent conditions with 28 kV and OD as close as possible to 1.5. Then, AGD ranged from 0.5 to 2.6 mGy with a mean of 1.3 mGy. Image viewing conditions were generally unsatisfying with ambient light up to 500 lx and most of the viewing boxes with luminance between 1000 and 2000 cd per m(2). TOR(MAM) scoring of images taken in clinical and referent conditions was done by local radiologists in local image viewing conditions and by the referent radiologist in good image viewing conditions. Importance of OD and image viewing conditions for diagnostic information were analysed. The survey showed that the main problem in Croatia is the lack of written quality assurance/quality control (QA/QC) procedures. Consequently, equipment performance, image quality and dose are unstable and activities to improve image quality or to reduce the dose are not evidence-based. This survey also had an educational purpose, introducing in Croatia the QC based on European Commission Guidelines.

  16. Technical and clinical breast cancer screening performance indicators for computed radiography versus direct digital radiography

    Energy Technology Data Exchange (ETDEWEB)

    Bosmans, Hilde; Lemmens, Kim; Zanca, Federica; Ongeval, Chantal van; Steen, Andre van [University Hospitals Leuven, Department of Radiology, Leuven (Belgium); Hauwere, An de; Thierens, Hubert [Ghent University, QCC, Ghent (Belgium); Herck, Koen van; Bleyen, Luc; Mortier, Griet [Ghent University, Centrum voor Preventie en Vroegtijdige Opsporing van Kanker, Department of Public Health, Ghent (Belgium); Martens, Patrick [Vroegtijdige Opsporing Borstklierkanker West-Vlaanderen vzw, Bruges (Belgium); Putte, Gretel vande; Kellen, Eliane; Limbergen, Erik van [Leuven University Center of Cancer Screening, Leuven (Belgium)

    2013-10-15

    To compare technical and clinical screening performance parameters between computed radiography (CR) and direct digital radiography (DR) systems. The number of women screened with CR was 73,008 and with DR 116,945. Technical and patient dose survey data of 25 CR and 37 DR systems were available. Technical performance was expressed by threshold thickness values at the mean glandular dose (MGD) level of routine practice. Clinical indicators included recall rate (RR), cancer detection rate (CDR), percentage of ductal carcinoma in situ (DCIS), percentage of cancers with T-scores smaller than 1 cm and positive predictive value (PPV). Contrast threshold values for the 0.1-mm gold disk were 1.44 {mu}m (SD 0.13 {mu}m) for CR and 1.20 {mu}m (SD 0.13 {mu}m for DR). MGD was 2.16 mGy (SD 0.36 mGy) and 1.35 mGy (SD 0.32 mGy) for CR and DR respectively. We obtained for CR, respectively DR, the following results: RR in the first round of 5.48 % versus 5.61 %; RR in subsequent rounds of 2.52 % versus 2.65 %; CDR of 0.52 % versus 0.53 %; DCIS of 0.08 % versus 0.11 %; a rate of cancers with T-scores smaller than 1 cm of 0.11 % versus 0.11 %; PPV of 18.45 % versus 18.64 %; none of them was significantly different. Our screening indicators are reassuring for the use of CR and DR, with CR operating at 60 % higher MGD. (orig.)

  17. Dosimetric evaluation in panoramic and tele-radiography procedures; Avaliacao dosimetrica em procedimentos de radiografia panoramica e teleradiografias

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Georgge Gomes

    2004-07-01

    The present work had as an objective to evaluate the skin surface entrance dose in panoramic and tele radiography procedures in three clinics in Recife - Pernambuco - Brazil, and to contribute with data for the determination of reference levels for super cited extra oral procedures, for this purpose, operational conditions in 3 clinics were evaluated in Recife, aiming to evaluate the existence and integrity of the radioprotection equipment, manner and conditions of image processing; and radiographic equipment parameters such as the dimension of the irradiation filed, the total filtration, the exposure time and the potential applied to the X ray tube. For an estimation of the skin entrance dose of the patient, the phantom Randon Alderson and thermoluminescence dosemeters were used. From these values and the conversion factors determined by the Monte Carlo technique, with the phantom MAX it was possible to estimate the dose absorbed in the organ due to the tele radiography procedures. Regarding panoramic radiography the study showed that the more elevated doses occurred in the parotid gland region which is near rotational venters. In the case of tele radiography the highest dose value occurred in the regions corresponding to the temporal lobe of the brain, followed by linfonodes, ears and parotid glands. The doses absorbed in the eyes and the thyroid gland were, 0.037 mGy and 0.002 mGy in Clinic A and 0.062 mGy and 0.003 mGy in Clinic C, respectively. Regarding equipment test, inadequacy was found in the beam collimation in Clinic A and in the reproducibility of the X ray exposure in Clinic C. The total filtration in both clinics was inadequate.(author)

  18. The Effects of Amine Based Missile Fuels on the Activated Sludge Process.

    Science.gov (United States)

    1979-10-01

    the 347 mg/i measured COD can be attributed to the fuel itself. Using semibatch reactor kinetics, it is possible to calculate the effluent COD given the...Specific Substrate Utilization as a Function of Substrate Concentration, 140nod Plot .. ............ 3 2 Completely Mixed Reactor with Cellular...Residence Time .. ........... 13 5 Laboratory Schematic......................16 6 Mixing Chamber Used to Achieve C1 in Reactors 1 to 4, C2 in Reactors 9 to

  19. Diamond Detectors as Beam Monitors

    CERN Document Server

    Dehning, B; Dobos, D; Pernegger, H; Griesmayer, E

    2010-01-01

    CVD diamond particle detectors are already in use in the CERN experiments ATLAS, CMS, LHCb and ALICE and at various particle accelerator laboratories in USA and Japan. This is a proven technology with high radiation tolerance and very fast signal read-out. It can be used for measuring single-particles as well as for high-intensity particle cascades, for timing measurements on the nanosecond scale and for beam protection systems. The radiation tolerance is specified with 10 MGy.

  20. Computation of thyroid doses and carcinogenic radiation risks to patients undergoing neck CT examinations.

    Science.gov (United States)

    Huda, Walter; Spampinato, Maria V; Tipnis, Sameer V; Magill, Dennise

    2013-10-01

    The aim of the study was to investigate how differences in patient anatomy and CT technical factors in neck CT impact on thyroid doses and the corresponding carcinogenic risks. The CTDIvol and dose-length product used in 11 consecutive neck CT studies, as well as data on automatic exposure control (AEC) tube current variation(s) from the image DICOM header, were recorded. For each CT image that included the thyroid, the mass equivalent water cylinder was estimated based on the patient cross-sectional area and average relative attenuation coefficient (Hounsfield unit, HU). Patient thyroid doses were estimated by accounting for radiation intensity at the location of the patient's thyroid, patient size and the scan length. Thyroid doses were used to estimate thyroid cancer risks as a function of patient demographics using risk factors in BEIR VII. The length of the thyroid glands ranged from 21 to 54 mm with an average length of 42 ± 12 mm. Water cylinder diameters corresponding to the central slice through the patient thyroid ranged from 18 to 32 cm with a mean of 25 ± 5 cm. The average CTDIvol (32-cm phantom) used to perform these scans was 26 ± 6 mGy, but the use of an AEC increased the tube current by an average of 44 % at the thyroid mid-point. Thyroid doses ranged from 29 to 80 mGy, with an average of 55 ± 19 mGy. A 20-y-old female receiving the highest thyroid dose of 80 mGy would have a thyroid cancer risk of nearly 0.1 %, but radiation risks decreased very rapidly with increasing patient age. The key factors that affect thyroid doses in neck CT examinations are the radiation intensity at the thyroid location and the size of the patient. The corresponding patient thyroid cancer risk is markedly influenced by patient sex and age.

  1. Morphological and histological studies on freshwater prawn Macrobrachium rosenbergii (de man) irradiated with (60)Co gamma radiation.

    Science.gov (United States)

    Stalin, A; Broos, K V; Sadiq Bukhari, A; Syed Mohamed, H E; Singhal, R K; Venu-Babu, P

    2013-11-15

    This study was framed to investigate the (60)Co gamma radiation induced morphological and histological variations in freshwater prawn Macrobrachium rosenbergii. The LD50 value of (60)Co gamma irradiated M. rosenbergii observed (by probit analysis) at 30 Gy. Prawns were irradiated to four different dose levels (3 mGy, 30 mGy, 300 mGy and 3,000 mGy) using Theratron Phoenix TeleCobalt Unit [P-33] and one control group (without irradiation) maintained separately. Irradiated groups exhibited several morphological variations such as discoloration; damaged rostrum; opaque coloration in cephalothorax; black bands and dot formation in abdomen; deformed uropods and telson in tail regions when compared with control group. The Hepato Somatic Index reflected the severity of radiation on hepatopancreas. Histological variations in gills, hepatopancreas and muscles of irradiated groups were observed. In gills, structural changes such as swollen and fused lamellae, abnormal gill tips, hyperplasic, necrotic and clavate-globate lamellae were observed in gamma irradiated prawns. Accumulation of hemocytes in hemocoelic space, interstitial sinuses filled with abnormal infiltrated hemocytes, the tubular epithelium with ruptured basal laminae, abnormal and coagulated lumen, necrotic tubules, thickened basal laminae, tissue debris, necrotic hepatocytes were observed in irradiated prawn hepatopancreas. In muscle, shrinkage of muscular fiber and necrotic musculature were observed in irradiated prawns. These structural alterations of the organs it is felt could affect the vital physiological functions such as respiration, osmotic and ionic regulation in gills and muscles; absorption, storage and secretion of the hepatopancreas which in turn could adversely affect the growth and survival of freshwater prawn M. rosenbergii.

  2. CT-guided screw fixation of vertical sacral fractures in local anaesthesia using a standard CT; CT-kontrollierte Schraubenosteosynthese von vertikalen Frakturen des hinteren Beckenringes in Lokalanaesthesie

    Energy Technology Data Exchange (ETDEWEB)

    Reuther, G.; Dehne, I. [Thueringen-Klinik, Saalfeld (Germany). Radiologische Klinik; Roehner, U.; Will, T.; Petereit, U. [Thueringen-Klinik, Saalfeld (Germany). Orthopaedics and Trauma Surgery

    2014-12-15

    To evaluate time efficiency, radiation dose, precision and complications of percutaneous iliosacral screw placement under CT-guidance in local anaesthesia. Retrospective analysis of 143 interventions in 135 patients during a period of 42 months. Implant failures could be evaluated in 85/182 screws and bony healing or refracturing in 46/182 screws. A total of 182 iliosacral screw placements in 179 vertical sacral fractures (105 unilateral, 37 bilateral) took place in 135 patients. 166/179 of the sacral fractures were detected in Denis zone 1, 10 in Denis zone 2 and 3 in Denis zone 3. No screw misplacements including the simultaneous bilateral procedures were noted. The average time for a unilateral screw placement was 23 minutes (range: 14-52 minutes) and 35 minutes (range: 21-60 minutes) for simultaneous bilateral screwing. The dose length product was 365 mGy x cm (range: 162-1014 mGy x cm) for the unilateral and 470 mGy x cm (range: 270-1271 mGy x cm) for the bilateral procedure. 1 gluteal bleeding occurred as the only acute minor complication (0.7%). Fracture healing was verified with follow-up CTs in 42/46 sacral fractures after screw placement. Backing out occurred in 12/85 screws between 6 and 69 days after intervention. In 8 patients contralateral stress fractures were detected after unilateral screw placement between day 10 and 127 (average: 48 days). CT-guided iliosacral screw placement in sacral fractures is a safe tool providing a very high precision. The radiation dose is in the order of a diagnostic CT of the pelvis for both unilateral and bilateral screws. Contralateral stress fractures in unilateral screw placements have to be considered during the first weeks after intervention.

  3. Effect of Photon Hormesis on Dose Responses to Alpha Particles in Zebrafish Embryos

    Science.gov (United States)

    Ng, Candy Yuen Ping; Cheng, Shuk Han; Yu, Kwan Ngok

    2017-01-01

    Photon hormesis refers to the phenomenon where the biological effect of ionizing radiation with a high linear energy transfer (LET) value is diminished by photons with a low LET value. The present paper studied the effect of photon hormesis from X-rays on dose responses to alpha particles using embryos of the zebrafish (Danio rerio) as the in vivo vertebrate model. The toxicity of these ionizing radiations in the zebrafish embryos was assessed using the apoptotic counts at 20, 24, or 30 h post fertilization (hpf) revealed through acridine orange (AO) staining. For alpha-particle doses ≥ 4.4 mGy, the additional X-ray dose of 10 mGy significantly reduced the number of apoptotic cells at 24 hpf, which proved the presence of photon hormesis. Smaller alpha-particle doses might not have inflicted sufficient aggregate damages to trigger photon hormesis. The time gap T between the X-ray (10 mGy) and alpha-particle (4.4 mGy) exposures was also studied. Photon hormesis was present when T ≤ 30 min, but was absent when T = 60 min, at which time repair of damage induced by alpha particles would have completed to prevent their interactions with those induced by X-rays. Finally, the drop in the apoptotic counts at 24 hpf due to photon hormesis was explained by bringing the apoptotic events earlier to 20 hpf, which strongly supported the removal of aberrant cells through apoptosis as an underlying mechanism for photon hormesis. PMID:28208665

  4. Evaluation of anti-gingivitis benefits of stannous fluoride dentifrice among triclosan dentifrice users.

    Science.gov (United States)

    He, Tao; Barker, Matthew L; Biesbrock, Aaron; Miner, Melanie; Amini, Pejmon; Goyal, C Ram; Qaqish, Jimmy

    2013-08-01

    To evaluate the anti-gingivitis benefits of a 0.454% highly bioavailable stannous fluoride dentifrice (SnF2) relative to a 0.3% triclosan/copolymer dentifrice (triclosan/copolymer) among triclosan/copolymer dentifrice users with residual gingivitis. This was a randomized, controlled, double-blind, parallel group, 2-month clinical study. Self-reported triclosan/copolymer dentifrice users were recruited and provided with triclosan/copolymer dentifrice to use for 1 month. After this 1-month acclimation period, subjects who had residual gingivitis at the baseline visit were randomized to either the SnF2 dentifrice or the triclosan/copolymer dentifrice (positive control). Subjects performed their treatment unsupervised using their assigned dentifrice following manufacturers' usage instructions for 2 months. The Gingival Bleeding Index (GBI) and Modified Gingival Index (MGI) were used to measure gingivitis benefits at baseline and Month 2. An analysis of covariance was performed to compare treatment groups for the post-baseline scores as well as change from baseline, with the baseline score as a covariate. All comparisons were two-sided at the 0.05 level of significance. A total of 150 subjects were randomized to treatment. Both treatment groups experienced significant reductions in number of bleeding sites, gingival bleeding index (GBI), and gingival inflammation (MGI) relative to baseline (P dentifrice group demonstrated significantly lower adjusted mean scores versus the triclosan/copolymer group for number of bleeding sites, GBI, and MGI (P < 0.001). Between-treatment group comparisons for change from baseline values showed that the improvement in number of bleeding sites from baseline for the SnF2 group was 49% greater versus that of the triclosan/copolymer group (P < 0.001), and the GBI and MGI improvements from baseline for the SnF2 group were 48% and 37%, greater, respectively, relative to the triclosan/copolymer group (P < 0.001).

  5. Assessment of the effects of a stannous fluoride dentifrice on gingivitis in a two-month positive-controlled clinical study.

    Science.gov (United States)

    He, Tao; Barker, Matthew L; Biesbock, A R; Sharma, N C; Qaqish, J; Goyal, C R

    2012-01-01

    The purpose of this study was to evaluate the anti-gingivitis effectiveness of a 0.454% stannous fluoride test dentifrice relative to a marketed positive-control triclosan-containing dentifrice in adults with gingivitis. This was a two-month, randomized and controlled, double-blind, parallel group, single-center investigation involving 150 adults with existing mild to moderate gingivitis. Pre-treatment gingivitis levels were assessed at baseline using the Lobene Modified Gingival Index (MGI) and the Gingival Bleeding Index (GBI). Qualified subjects were randomly assigned to either a 0.454% stannous fluoride test dentifrice or a marketed, positive-control 0.30% triclosan/copolymer dentifrice. Subjects then brushed for two months unsupervised in the home setting with their assigned dentifrice per manufacturer's instructions. At Month 2, subjects were re-evaluated for gingivitis via MGI and GBI examinations. All 150 enrolled subjects completed the trial and were evaluable. Both the stannous fluoride test and triclosan/copolymer control dentifrices provided statistically significant reductions in average MGI, GBI, and number of bleeding sites relative to pre-treatment (p dentifrice group was 65% greater for number of bleeding sites, 62% greater for GBI, and 45% greater for MGI compared to the triclosan/copolymer positive-control group, with groups differing significantly (p dentifrices were well-tolerated. An advanced stannous fluoride test dentifrice provided superior reductions in gingival inflammation and gingival bleeding compared to a commercially available triclosan/copolymer positive-control dentifrice after two months of tooth brushing.

  6. Lattice parameters and electronic structure of BeMgZnO quaternary solid solutions: Experiment and theory

    Science.gov (United States)

    Toporkov, M.; Demchenko, D. O.; Zolnai, Z.; Volk, J.; Avrutin, V.; Morkoç, H.; Özgür, Ü.

    2016-03-01

    BexMgyZn1-x-yO semiconductor solid solutions are attractive for UV optoelectronics and electronic devices owing to their wide bandgap and capability of lattice-matching to ZnO. In this work, a combined experimental and theoretical study of lattice parameters, bandgaps, and underlying electronic properties, such as changes in band edge wavefunctions in BexMgyZn1-x-yO thin films, is carried out. Theoretical ab initio calculations predicting structural and electronic properties for the whole compositional range of materials are compared with experimental measurements from samples grown by plasma assisted molecular beam epitaxy on (0001) sapphire substrates. The measured a and c lattice parameters for the quaternary alloys BexMgyZn1-x with x = 0-0.19 and y = 0-0.52 are within 1%-2% of those calculated using generalized gradient approximation to the density functional theory. Additionally, composition independent ternary BeZnO and MgZnO bowing parameters were determined for a and c lattice parameters and the bandgap. The electronic properties were calculated using exchange tuned Heyd-Scuseria-Ernzerhof hybrid functional. The measured optical bandgaps of the quaternary alloys are in good agreement with those predicted by the theory. Strong localization of band edge wavefunctions near oxygen atoms for BeMgZnO alloy in comparison to the bulk ZnO is consistent with large Be-related bandgap bowing of BeZnO and BeMgZnO (6.94 eV). The results in aggregate show that precise control over lattice parameters by tuning the quaternary composition would allow strain control in BexMgyZn1-x-yO/ZnO heterostructures with possibility to achieve both compressive and tensile strain, where the latter supports formation of two-dimensional electron gas at the interface.

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

    Science.gov (United States)

    Manesh, Sara Shakeri; Sangsuwan, Traimate; Wojcik, Andrzej; Haghdoost, Siamak

    2015-10-01

    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 50mGy adapting dose administered acutely (0.40Gy/min) or chronically (1.4mGy/h or 4.1mGy/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 100mGy and 1Gy 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 50mGy at 1.4mGy/h followed by 1Gy acute exposure as challenging dose. Importantly, at single dose exposures (1 Gy or 100mGy), no differences at the level of mutation were found comparing different dose rates. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Radiation dose and cancer risk from pediatric CT examinations on 64-slice CT: A phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Feng Shiting [Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou (China); Law, Martin Wai-Ming [Department of Clinical Oncology, Queen Mary Hospital (Hong Kong); Huang Bingsheng [Department of Diagnostic Radiology, University of Hong Kong (Hong Kong); Ng, Sherry [Department of Clinical Oncology, Queen Mary Hospital (Hong Kong); Li Ziping; Meng Quanfei [Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou (China); Khong, Pek-Lan, E-mail: plkhong@hkucc.hku.hk [Department of Diagnostic Radiology, University of Hong Kong (Hong Kong)

    2010-11-15

    Objective: To measure the radiation dose from CT scans in an anthropomorphic phantom using a 64-slice MDCT, and to estimate the associated cancer risk. Materials and methods: Organ doses were measured with a 5-year-old phantom and thermoluminescent dosimeters. Four protocols; head CT, thorax CT, abdomen CT and pelvis CT were studied. Cancer risks, in the form of lifetime attributable risk (LAR) of cancer incidence, were estimated by linear extrapolation using the organ radiation doses and the LAR data. Results: The effective doses for head, thorax, abdomen and pelvis CT, were 0.7 mSv, 3.5 mSv, 3.0 mSv, 1.3 mSv respectively. The organs with the highest dose were; for head CT, salivary gland (22.33 mGy); for thorax CT, breast (7.89 mGy); for abdomen CT, colon (6.62 mGy); for pelvis CT, bladder (4.28 mGy). The corresponding LARs for boys and girls were 0.015-0.053% and 0.034-0.155% respectively. The organs with highest LARs were; for head CT, thyroid gland (0.003% for boys, 0.015% for girls); for thorax CT, lung for boys (0.014%) and breast for girls (0.069%); for abdomen CT, colon for boys (0.017%) and lung for girls (0.016%); for pelvis CT, bladder for both boys and girls (0.008%). Conclusion: The effective doses from these common pediatric CT examinations ranged from 0.7 mSv to 3.5 mSv and the associated lifetime cancer risks were found to be up to 0.16%, with some organs of higher radiosensitivity including breast, thyroid gland, colon and lungs.

  9. Pediatric patient doses in interventional cardiology procedures; Doses em paciente pediatrico em procedimentos de cardiologia intervencionista

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, R.B.; Murata, C.H.; Moreira, A.C., E-mail: rbitelli2012@gmail.com, E-mail: camila.murata@gmail.com, E-mail: antonio.xray@gmail.com [Universidade Federal de Sao Paulo (UNIFESP), Sao Paulo, SP (Brazil). Escola Pulista de Medicina; Khoury, H.J.; Borras, C., E-mail: hjkhoury@gmail.com, E-mail: cariborras@starpower.net [Universidade Federal de Pernambuco (DEN/UFPE), Recife, PE (Brazil). Dept. de Engenharia Nuclear; Silva, M.S.R da, E-mail: msrochas2003@yahoo.com.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFPE), Recife, PE (Brazil)

    2014-07-01

    The radiation doses from interventional procedures is relevant when treating children because of their greater radiosensitivity compared with adults. The purposes of this paper were to estimate the dose received by 18 pediatric patients who underwent cardiac interventional procedures and to correlate the maximum entrance surface air kerma (Ke,max), estimated with radiochromic films, with the cumulative air kerma values displayed at the end of procedures. This study was performed in children up to 6 years. The study was performed in two hospitals, one located in Recife and the other one in São Paulo. The x-ray imaging systems used were Phillips Allura 12 model with image intensifier system and a Phillips Allura FD10 flat panel system. To estimate the Ke,max on the patient’s skin radiochromic films(Gafchromic XR-RV2) were used. These values were estimated from the maximum optical density measured on film using a calibration curve. The results showed cumulative air kerma values ranging from 78.3- 500.0mGy, with a mean value of 242,3 mGy. The resulting Ke,max values ranged from 20.0-461.8 mGy, with a mean value of 208,8 mGy. The Ke,max values were correlated with the displayed cumulative air kerma values. The correlation factor R² was 0.78, meaning that the value displayed in the equipment’s console can be useful for monitoring the skin absorbed dose throughout the procedure. The routine fluoroscopy time records is not able by itself alert the physician about the risk of dose exceeding the threshold of adverse reactions, which can vary from an early erythema to serious harmful skin damage. (author)

  10. First demonstration of rapid shutdown using neon shattered pellet injection for thermal quench mitigation on DIII-D

    Science.gov (United States)

    Commaux, N.; Shiraki, D.; Baylor, L. R.; Hollmann, E. M.; Eidietis, N. W.; Lasnier, C. J.; Moyer, R. A.; Jernigan, T. C.; Meitner, S. J.; Combs, S. K.; Foust, C. R.

    2016-04-01

    Shattered pellet injection (SPI) is one of the prime candidates for the ITER disruption mitigation system because of its deeper penetration and larger particle flux than massive gas injection (MGI) (Taylor et al 1999 Phys. Plasmas 6 1872) using deuterium (Commaux et al 2010 Nucl. Fusion 50 112001, Combs et al 2010 IEEE Trans. Plasma Sci. 38 400, Baylor et al 2009 Nucl. Fusion 49 085013). The ITER disruption mitigation system will likely use mostly high Z species such as neon because of more effective thermal mitigation and pumping constraints on the maximum amount of deuterium or helium that could be injected. An upgrade of the SPI on DIII-D enables ITER relevant injection characteristics in terms of quantities and gas species. This upgraded SPI system was used on DIII-D for the first time in 2014 for a direct comparison with MGI using identical quantities of neon. This comparison enabled the measurements of density perturbations during the thermal quench (TQ) and radiated power and heat loads to the divertor. It showed that SPI using similar quantities of neon provided a faster and stronger density perturbation and neon assimilation, which resulted in a lower conducted energy to the divertor and a faster TQ onset. Radiated power data analysis shows that this was probably due to the much deeper penetration of the neon in the plasma inducing a higher core radiation than in the MGI case. This experiment shows also that the MHD activity during an SPI shutdown (especially during the TQ) is quite different compared to MGI. This favorable TQ energy dissipation was obtained while keeping the current quench (CQ) duration within acceptable limits when scaled to ITER.

  11. DNA damage in lymphocytes induced by cardiac CT and comparison with physical exposure parameters

    Energy Technology Data Exchange (ETDEWEB)

    Fukumoto, Wataru; Tatsugami, Fuminari; Awai, Kazuo [Department of Diagnostic Radiology, Institute of Biomedical Health Sciences, Hiroshima University, Hiroshima (Japan); Ishida, Mari; Sakai, Chiemi [Institute of Biomedical and Health Sciences, Department of Cardiovascular Physiology and Medicine, Hiroshima University, Hiroshima (Japan); Tashiro, Satoshi [Hiroshima University, Department of Cellular Biology, Research Institute for Radiation Biology and Medicine, Hiroshima (Japan); Ishida, Takafumi [Institute of Clinical Research West Medical Center, Hiroshima (Japan); Nakano, Yukiko [Hiroshima University Hospital, Department of Cardiovascular Medicine, Hiroshima (Japan)

    2017-04-15

    To investigate whether physical exposure parameters such as the dose index (CTDI), dose length product (DLP), and size-specific dose estimate (SSDE) are predictive of DNA damage. In vitro, we scanned a phantom containing blood samples from five volunteers at CTDI 50, 100, and 150 mGy. One sample was not scanned. We also scanned samples in three different-size phantoms at CTDI 100 mGy. In vivo, we enrolled 45 patients and obtained blood samples before and after cardiac CT. The γ-H2AX foci were counted. In vitro, in the control and at CTDI 50, 100, and 150 mGy, the number of γ-H2AX was 0.94 ± 0.24 (standard error, SE), 1.28 ± 0.30, 1.91 ± 0.47, and 2.16 ± 0.20. At SSDE 180, 156, and 135 mGy, it was 2.41 ± 0.20, 1.91 ± 0.47, and 1.42 ± 0.20 foci/cell. The γ-H2AX foci were positively correlated with the radiation dose and negatively correlated with the body size. In vivo, the γ-H2AX foci were significantly increased after CT (from 1.21 ± 0.19 to 1.92 ± 0.22 foci/cell) and correlated with CTDI, DLP, and SSDE. DNA damage was induced by cardiac CT. There was a correlation between the physical exposure parameters and γ-H2AX. (orig.)

  12. Estimation of the minimum dose required to measure ventricular width in follow-up cranial computed tomography (CCT) in children with hydrocephalus

    Energy Technology Data Exchange (ETDEWEB)

    Kirchhof, K. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik; Wohlgemuth, W.A.; Berlis, A. [Klinikum Augsburg (Germany). Klinik fuer Diagnostische Radiologie und Neuroradiologie

    2010-12-15

    Purpose: To estimate the minimum dose needed at follow-up cranial computed tomography (CCT) to reliably determine ventricular width in children with hydrocephalus. Materials and Methods: For the study, a phantom was created using the calvarium of an infant which was filled with gelatin and the shaped inner cones of two carrots serving as lateral ventricles. The phantom was scanned ten times with two multi-slice CTs (LightSpeed Ultra, GE, and Somatom Sensation, Siemens), using a tube current of 400, 350, 300, 250, 200, 150, and 100 mA, and a tube voltage of 140, 120, 100, and 80 kV. The width of both lateral ventricles was measured at 4 sites. The values derived from scans performed at 380 / 400 mA and 140 kV (LightSpeed/Somatom) served as a reference. Measurements scored 1 point if they did not differ by more than 0.5 mm from the reference values. Results: The radiation dose can be reduced from 61.0 mGy to 9.2 mGy (15.1 %) with LightSpeed and from 55.0 mGy to 8.0 mGy (14.6 %) with Somatom without impairing the reliability of ventricular width measurements. However, in the case of both scanners, certain combinations of tube voltage and current yielded less reliable measurements although the dose was higher and the pixel noise was lower. Conclusion: There is no single cut-off dose or setting for tube voltage and current which guarantees reliable ventricular width measurements with the least radiation exposure for both scanners. As a guideline, it is safe to use the standard protocols with a reduced tube current of 100 kV. (orig.)

  13. Radiation dose to patients and radiologists during transcatheter arterial embolization: comparison of a digital flat-panel system and conventional unit.

    Science.gov (United States)

    Suzuki, Shigeru; Furui, Shigeru; Kobayashi, Ikuo; Yamauchi, Teiyu; Kohtake, Hiroshi; Takeshita, Koji; Takada, Koichi; Yamagishi, Masafumi

    2005-10-01

    The objective of our study was to evaluate the exposure doses to patients and radiologists during transcatheter arterial embolization (TAE) for hepatocellular carcinoma (HCC) using a new angiographic unit with a digital flat-panel system. Doses were assessed for 24 procedures: 12 using a new unit with a digital flat-panel system and 12 using a conventional unit. Doses to patients' skin were evaluated with thermoluminescent dosimeters behind the left, middle, and right portions of the liver. The doses to the radiologists were measured by an electronic personal dosimeter placed on the chest outside a lead protector. The maximal skin doses to the patients and the dose equivalents, Hp(0.07), to the radiologists were compared between the two procedure groups with each angiographic unit. For procedures with the new unit, the mean maximal skin dose to the patients was 284 +/- 127 (SD) mGy (range, 130-467 mGy), and Hp(0.07) to the radiologists was 62.8 +/- 17.4 muSv. For procedures with the conventional unit, the maximal skin dose to the patients was 1,068 +/- 439 mGy (range, 510-1,882 mGy), and Hp(0.07) to the radiologists was 68.4 +/- 25.7 muSv. The maximal skin dose to the patients was significantly lower with the new unit than with the conventional unit (p < 0.0005). There was no significant difference in the Hp(0.07) to the radiologists between the two procedure groups. The new digital flat-panel system for angiographic imaging can reduce the radiation dose to patients' skin during TAE for HCC as compared with the conventional system.

  14. Effect of Photon Hormesis on Dose Responses to Alpha Particles in Zebrafish Embryos

    Directory of Open Access Journals (Sweden)

    Candy Yuen Ping Ng

    2017-02-01

    Full Text Available Photon hormesis refers to the phenomenon where the biological effect of ionizing radiation with a high linear energy transfer (LET value is diminished by photons with a low LET value. The present paper studied the effect of photon hormesis from X-rays on dose responses to alpha particles using embryos of the zebrafish (Danio rerio as the in vivo vertebrate model. The toxicity of these ionizing radiations in the zebrafish embryos was assessed using the apoptotic counts at 20, 24, or 30 h post fertilization (hpf revealed through acridine orange (AO staining. For alpha-particle doses ≥ 4.4 mGy, the additional X-ray dose of 10 mGy significantly reduced the number of apoptotic cells at 24 hpf, which proved the presence of photon hormesis. Smaller alpha-particle doses might not have inflicted sufficient aggregate damages to trigger photon hormesis. The time gap T between the X-ray (10 mGy and alpha-particle (4.4 mGy exposures was also studied. Photon hormesis was present when T ≤ 30 min, but was absent when T = 60 min, at which time repair of damage induced by alpha particles would have completed to prevent their interactions with those induced by X-rays. Finally, the drop in the apoptotic counts at 24 hpf due to photon hormesis was explained by bringing the apoptotic events earlier to 20 hpf, which strongly supported the removal of aberrant cells through apoptosis as an underlying mechanism for photon hormesis.

  15. Fast accretion of the Earth with a late Moon-forming giant impact

    Science.gov (United States)

    Yu, Gang; Jacobsen, Stein B.

    2011-01-01

    Constraints on the formation history of the Earth are critical for understanding of planet formation processes. 182Hf-182W chronometry of terrestrial rocks points to accretion of Earth in approximately 30 Myr after the formation of the solar system, immediately followed by the Moon-forming giant impact (MGI). Nevertheless, some N-body simulations and 182Hf-182W and 87Rb-87Sr chronology of some lunar rocks have been used to argue for a later formation of the Moon at 52 to > 100 Myr. This discrepancy is often explained by metal-silicate disequilibrium during giant impacts. Here we describe a model of the 182W isotopic evolution of the accreting Earth, including constraints from partitioning of refractory siderophile elements (Ni, Co, W, V, and Nb) during core formation, which can explain the discrepancy. Our modeling shows that the concentrations of the siderophile elements of the mantle are consistent with high-pressure metal-silicate equilibration in a terrestrial magma ocean. Our analysis shows that the timing of the MGI is inversely correlated with the time scale of the main accretion stage of the Earth. Specifically, the earliest time the MGI could have taken place right at approximately 30 Myr, corresponds to the end of main-stage accretion at approximately 30 Myr. A late MGI (> 52 Myr) requires the main stage of the Earth’s accretion to be completed rapidly in < 10.7 ± 2.5 Myr. These are the two end member solutions and a continuum of solutions exists in between these extremes. PMID:22006299

  16. Effects of {gamma} and neutron irradiation on the optical absorption of pure silica core single-mode optical fibres from Nufern

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, A. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Martinez-Rivero, C. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Matorras, F. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Rodrigo, T. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Sobron, M. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Vila, I. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Virto, A.L. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Alberdi, J. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Arce, P. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Barcala, J.M. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Calvo, E. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Ferrando, A. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain)]. E-mail: Antonio.Ferrando@ciemat.es; Josa, M.I. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Luque, J.M. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Molinero, A. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Navarrete, J. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Oller, J.C. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Valdivieso, P. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Yuste, C. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Fenyvesi, A. [Institute of Nuclear Research, ATOMKI, Debrecen (Hungary); Molnar, J. [Institute of Nuclear Research, ATOMKI, Debrecen (Hungary)

    2006-09-15

    A measurement of the optical absorption, induced by photon irradiation up to a dose of 0.9 MGy, in Nufern silica core single-mode optical fibres is presented. In addition, the fibres were irradiated with neutrons, up to a total fluence of 2x10{sup 14} cm{sup -2} and the induced optical absorption was evaluated for four different wavelengths: 630, 670, 681 and 785 nm.

  17. ANALISIS KARAKTERISTIK KANDUNGAN PENCEMAR AIR LIMBAH DAN PROSES PENGOLAHAN AIR MINUM KABUPATEN BADUNG

    Directory of Open Access Journals (Sweden)

    AWANG ERRY SOFYAR IRAWAN

    2015-06-01

    Full Text Available Installation of water treatment is the required infrastructure in meeting the needs of clean water. During the process of water treatment it produces waste water as a byproduct that could potentially cause pollution if not properly treated. The research purposes of the study are to determine the effectiveness of compliance procedures for waste water treatment, the quality and quantity of waste water and its impact to the environment, as well as providing alternatives for waste water management strategies. Determination of samples were conducted by using purposive sampling method. Samples were taken at two sewer sedimentation and filtration points antl the other four points were taken in the water body and then compared with Governor of Bali Regulation No.8 year 2007. Samples were analywd both in situ and in the laboratory. To determine the effectiveness of the waste water treatment to the conformity assessment procedures, the field conditions were analyzed with a force-field analysis. The effectiveness of waste water management was categorized as moderate. The quality of waste water from the sedimentation basin shows the parameters of TSS (4957.50 mg/I and Mn (81.68 mg/I, of the tub filtration TSS (665 mg/I and Mn (12.60 mg/I. The quantity of waste sedimentation basin discharge (Q o.68 mg/sec, TSS pollutant load (3371.01 mg/sec, Mn (55.51 mg/sec, filtration basin discharge (Q o.68 mg/sec, load TSS pollutant (332.50 mg/sec, Mn (6.30 mg/sec. Based on the force-field analysis conducted, some alternative strategies were proposed such as building facilities for waste management, environmental m.inagement implementation based on the appropriate planning, implementation of waste water disposal permit including fulfill the technical conditions as required, technical capacity building of human resources, and land use.

  18. Non-thyroid cancer in Northern Ukraine in the post-Chernobyl period: Short Report

    OpenAIRE

    Hatch, M.; Ostroumova, E.; Brenner, A.; Federenko, Z; Gorokh, Y; Zvinchuk, O; Shpak, V.; Tereschenko, V.; Tronko, M.; Mabuchi, K

    2015-01-01

    The Chernobyl nuclear power plant accident in Ukraine in 1986 led to widespread radioactive releases into the environment - primarily of radioiodines and cesium – heavily affecting the northern portions of the country, with settlement-averaged thyroid doses estimated to range from 10 mGy to more than 10 Gy. The increased risk of thyroid cancer among exposed children and adolescents is well-established but the impact of radioactive contamination on the risk of other types of cancer is much les...

  19. Association of elevated radiation dose with mortality in patients with acute myocardial infarction undergoing percutaneous coronary intervention

    Energy Technology Data Exchange (ETDEWEB)

    Parikh, Puja B.; Prakash, Sheena; Tahir, Usman; Kort, Smadar; Gruberg, Luis; Jeremias, Allen, E-mail: allen.jeremias@stonybrook.edu

    2014-09-15

    Objectives: This study sought to identify clinical and procedural predictors of elevated radiation dose received by patients with acute myocardial infarction (AMI) undergoing percutaneous coronary intervention (PCI) and to determine if elevated radiation dose was predictive of mortality in this population. Background: Little data exist regarding the impact of excessive radiation burden on clinical outcomes in patients undergoing PCI. Methods: The study population included 1,039 patients who underwent PCI for an AMI between January 1, 2007 and December 31, 2008 at an academic tertiary care teaching hospital. Cumulative skin dose (measured in milligray [mGy]) was selected as a measurement of patient radiation burden. Clinical and procedural variables were analyzed in multiple logistic and linear regression models to determine predictors of higher skin dose, and its impact was evaluated on all-cause intermediate-term mortality at two years. Results: Median skin dose was 2120 mGy (IQR 1379–3190 mGy) in the overall population, of which 153 (20.8%) patients received an elevated skin dose (defined as a skin dose > 4,000 mGy). Independent predictors of elevated skin dose included male gender, obesity, multivessel intervention, and presentation with a non-ST-elevation MI (NSTEMI) versus an ST-elevation MI (STEMI). Increased skin dose was not predictive of intermediate-term mortality by multivariate analysis in the overall population or in either subgroup of STEMI and NSTEMI. Conclusions: In this contemporary observational study examining patients with AMI undergoing PCI, male gender, obesity, multivessel intervention, and presentation with a NSTEMI were associated with increased radiation exposure.

  20. [The reduction of the radiation dosage by means of storage phosphor-film radiography compared to a conventional film-screen system with a grid cassette on a skull phantom].

    Science.gov (United States)

    Heyne, J P; Merbold, H; Sehner, J; Neumann, R; Freesmeyer, M; Jonetz-Mentzel, L; Kaiser, W A

    1999-07-01

    How much can the radiation dose be reduced for skull radiography by using digital luminescence radiography (DLR) compared to a conventional screen film system with a grid cassette? A skull phantom (3M) was x-rayed in anterior-posterior orientation using both a conventional screen film system with grid cassette and DLR (ADC-70, Agfa). The tube current time product (mAs) was diminished gradually while keeping the voltage constant. The surface entrance dose was measured by a sensor of Dosimax (Wellhöfer). Five investigators evaluated the images by characteristic and critical features, spatial resolution and contrast. The surface entrance dose at 73 kV/22 mAs was 0.432 mGy in conventional screen film system and 0.435 mGy in DLR. The images could be evaluated very well down to an average dose of 71% (0.308 mGy; SD 0.050); sufficient images were obtained down to an average dose of 31% (0.136 mGy; SD 0.065). The resolution of the line pairs were reduced down to 2 levels depending on the investigator. Contrast was assessed as being very good to sufficient. The acceptance of the postprocessed images (MUSICA-software) was individually different and resulted in an improvement of the assessment of bone structures and contrast in higher dose ranges only. For the sufficient assessment of a possible fracture/of paranasal sinuses/of measurement of the skull the dose can be reduced to at least 56% (phi 31%; SD 14.9%)/40% (phi 27%; SD 9.3%)/18% (phi 14%; SD 4.4%). Digital radiography allows question-referred exposure parameters with clearly reduced dose, so e.g. for fracture exclusion 73 kV/12.5 mAs and to skull measurement 73 kV/4 mAs.

  1. Dose Reduction to the Thyroid Gland in Pediatric Chest Radiography

    Directory of Open Access Journals (Sweden)

    Vahid Karami

    2016-07-01

    Full Text Available Background  It is remain a main concern that pediatric chest radiographies contribute to the significant radiation exposure to the thyroid gland as a more susceptible organ to radiation induced cancer. The aim of this study was to evaluate the entrance surface dose (ESD of pediatric chest radiography compared to the diagnostic reference levels (DRL and evaluation the efficacy of the lead (Pb shield in radiation dose reduction to the thyroid gland.Materials and Methods After assessing each patient against specific inclusion-exclusion criteria, 40 pediatric patients who were undergoing anterior-posterior (AP projection of the chest x-ray were considered eligible for this study. The ESD of the chest and also ESD of thyroid gland with and without a 1 mm butterfly-shaped lead shield which placed on the thyroid gland were measured using high sensitive thermo luminescent dosimeters (TLD-GR 200.Results The average of ESD for chest radiography was 0.068+ 0.006 mGy (0.021 - 0.232 mGy. The unshielded average thyroid ESD was 0.065 + 0.003 mGy compared to the shielded average thyroid ESD of 0.001 + 0.0005 mGy. The use of Pb-shield produced a statistically significant decrease in the average thyroid dose by about 97% (P< 0.001. Conclusion The use of Pb-thyroid shield in the AP projection of pediatric chest radiography has potential to reduced radiation dose without compromising image quality.

  2. Lead versus bismuth-antimony shield for fetal dose reduction at different gestational ages at CT pulmonary angiography.

    Science.gov (United States)

    Chatterson, Leslie C; Leswick, David A; Fladeland, Derek A; Hunt, Megan M; Webster, Stephen T

    2011-08-01

    To compare the effective fetal dose reduction at different stages of gestation during maternal computed tomographic (CT) pulmonary angiography by using traditional lead apron and bismuth-antimony shields combined with limited z-axis and tube current. Phantom with gravid prosthesis, 0.5-mm lead, and two grades of bismuth-antimony shield was used. Thermoluminescent dosimeters (TLDs) measured radiation in the first- to third-trimester uterus. Fetal dose was determined for each gestation by using 100 kVp to the costophrenic angles (CPAs) with and without shielding for a total of 12 scans. Eight third-trimester scans were used to compare shields using 120 kVp to CPAs versus those using 100 kVp to the diaphragm. Average fetal dose increased with gestation with use of 100 kVp to CPAs, from 0.11 mGy in first trimester to 0.50 mGy in third trimester. Average third-trimester unshielded fetal dose was reduced from 0.82 mGy by using 120 kVp to CPAs to 0.17 mGy (79%, P Lead apron reduced dose more than either of the bismuth-antimony shields (72%-79% vs 57%-81%) with use of 100 kVp to CPAs. Shields reduced the dose by 73% (lead), 62% (90% attenuation bismuth-antimony), and 72% (95% attenuation bismuth-antimony) (P shields was demonstrated with 100 kVp to the diaphragm (P shields at reducing fetal dose. Shielding improves reduction with no significant difference between lead and bismuth-antimony shields when conservative scanning parameters are observed. © RSNA, 2011.

  3. A comparison between the effect of All-Ceramic and metal-ceramic restorations on the plaque accumulation

    Directory of Open Access Journals (Sweden)

    Ezatollah Jalalian

    2015-07-01

    Full Text Available Background and Aims: Tooth crowning often leads to changes in periodontal index through changes in emergence profile zone. The purpose of this study was to compare the effect of metal-ceramic with that ofAll-Ceramic restorations on the plaque a accumulation.   Materials and Methods: In this clinical trial, we used 102 teeth covered with metal-ceramic and all-ceramic restorations. Before and after crowning, plaque index (PI and gingival indexes (MGl were measured. Data were analyzed using covariance (ANCOVA test.   Results: Measured PI and MGI (Mean±SD in PFM Group prior to crowning were (1.96±0.38 and (1.45±0.48, respectively. In metal-ceramic restorations group, six months after crowning, measured PI and MGI (Mean±SD were (1.22±0.49 and (1.82±0.61, respectively. Measured PI and MGI (Mean±SD in All-Ceramic Group prior to crowning were (1.22±0.52 and (1.25±0.29, respectively. In All-Ceramic, six months after crowning, measured PI and MGI (Mean±SD were (0.88±0.51 and (1.43±0.50, respectively. ANOVA test showed statistical significance difference between metal-ceramic and All-Ceramic Groups in Indexes (P<0.001.   Conclusion: Metal-ceramic and All-Ceramic crowns were associated with inflammatory changes in gingival. Metal-ceramic restorations were associated with higher inflammatory indexes compared with All-Ceramic crowns.

  4. Dose-rate effects of protons on in vivo activation of nuclear factor-kappa B and cytokines in mouse bone marrow cells

    Energy Technology Data Exchange (ETDEWEB)

    Rithidech, K.N.; Rusek, A.; Reungpatthanaphong, P.; Honikel, L.; Simon, S.R.

    2010-05-28

    The objective of this study was to determine the kinetics of nuclear factor-kappa B (NF-{kappa}B) activation and cytokine expression in bone marrow (BM) cells of exposed mice as a function of the dose rate of protons. The cytokines included in this study are pro-inflammatory [i.e., tumor necrosis factor-alpha (TNF-{alpha}), interleukin-1beta (IL-1{beta}), and IL-6] and anti-inflammatory cytokines (i.e., IL-4 and IL-10). We gave male BALB/cJ mice a whole-body exposure to 0 (sham-controls) or 1.0 Gy of 100 MeV protons, delivered at 5 or 10 mGy min{sup -1}, the dose and dose rates found during solar particle events in space. As a reference radiation, groups of mice were exposed to 0 (sham-controls) or 1 Gy of {sup 137}Cs {gamma} rays (10 mGy min{sup -1}). After irradiation, BM cells were collected at 1.5, 3, 24 h, and 1 month for analyses (five mice per treatment group per harvest time). The results indicated that the in vivo time course of effects induced by a single dose of 1 Gy of 100 MeV protons or {sup 137}Cs {gamma} rays, delivered at 10 mGy min{sup -1}, was similar. Although statistically significant levels of NF-{kappa}B activation and pro-inflammatory cytokines in BM cells of exposed mice when compared to those in the corresponding sham controls (Student's t-test, p < 0.05 or < 0.01) were induced by either dose rate, these levels varied over time for each protein. Further, only a dose rate of 5 mGy min{sup -1} induced significant levels of anti-inflammatory cytokines. The results indicate dose-rate effects of protons.

  5. Comparison of the radiation dose from cone beam computed tomography and multidetector computed tomography in examinations of the hand; Vergleich der Strahlendosis von Cone-Beam Computertomografie und Multidetektor Computertomografie in Untersuchungen der Hand

    Energy Technology Data Exchange (ETDEWEB)

    Neubauer, J.; Neubauer, C.; Gerstmair, A.; Krauss, T.; Kotter, E.; Langer, M. [University Medical Center Freiburg (Germany). Dept. of Radiology; Reising, K. [University Medical Center Freiburg (Germany). Dept. of Orthopedics and Trauma Surgery; Zajonc, H. [University Medical Center Freiburg (Germany). Dept. of Plastic and Hand Surgery; Fiebich, M.; Voigt, J. [University of Applied Sciences, Giessen (Germany). Inst. of Medical Physics and Radiation Protection

    2016-05-15

    Comparison of radiation dose of cone beam computed tomography (CBCT) and multidetector computed tomography (MDCT) in examinations of the hand. Dose calculations were carried out by means of Monte Carlo simulations in MDCT and CBCT. A corpse hand was examined in a 320-row MDCT scanner and a dedicated extremities CBCT scanner with standard protocols and multiple low-dose protocols. The image quality of the examinations was evaluated by 5 investigators using a Likert scale from 1 (very good) to 5 (very poor) regarding depiction of cortical bone, cancellous bone, joint surfaces, soft tissues and artifacts. For a sum of ratings of all structures < 50 a good overall image quality was expected. The studies with at least good overall image quality were compared with respect to the dose. The dose of the standard examination was 13.21 (12.96 to 13.46 CI) mGy in MDCT and 7.15 (6.99 to 7.30 CI) mGy in CBCT. The lowest dose in a study with good overall image quality was 4.54 (4.43 to 4.64 CI) mGy in MDCT and 5.72 (5.59 to 5.85 CI) mGy in CBCT. Although the dose of the standard protocols in the CBCT is lower than in the MDCT, the MDCT can realize a good overall image quality at a lower dose than the CBCT. Dose optimization of CT examination protocols for the hand is useful in both modalities, the MDCT has an even greater potential for optimization.

  6. 地西他滨%decitabine

    Institute of Scientific and Technical Information of China (English)

    陈娜

    2007-01-01

    @@ 地西他滨(decitabine)分别于2006年4月和5月由欧洲EMEA和美国FDA批准上市,是用于治疗原发性和继发性骨髓增生异常综合征(MDS)的药物.该药由MGI Pharma公司开发,商品名为Dacogen,为注射剂.

  7. Estimation of the fetal dose by dose measurement during an irradiation of a parotid tumor; Estimation de la dose foetale par mesure de dose lors d'une irradiation d'une tumeur de la parotide

    Energy Technology Data Exchange (ETDEWEB)

    Marchesi, V.; Graff-Cailleaud, P.; Peiffert, D. [Centre Alexis-Vautrin, 54 - Vandoeuvre-les-Nancy (France); Noel, A. [Institut National Polytechnique de Lorraine, CRAN CNRS UMR-7039, 54 - Vandoeuvre-les-Nancy (France)

    2006-11-15

    The irradiation of a five months pregnant patient has been made for a right parotid attack. In conformation with the legislative texts relative to radiation protection ( publication 84 of the ICRP) an estimation of the dose received for the fetus has been led by dose measurement on phantom. With the dose limit ( 100 mGy) recommended in the publication 84 of the ICRP neither modification of the treatment nor abortion was necessary. (N.C.)

  8. Time extrapolation of radiolytic degradation product kinetics: the case of polyurethane; Extrapolation dans le temps des cinetiques de production des produits de degradation radiolytique: application a un polyurethane

    Energy Technology Data Exchange (ETDEWEB)

    Dannoux, A

    2007-02-15

    The prediction of the environmental impact of organic materials in nuclear waste geological storage needs knowledge of radiolytic degradation mechanisms and kinetics in aerobic and anaerobic conditions. In this framework, the effect of high doses (> MGy) and the variation of dose rate have to be considered. The material studied is a polyurethane composed of polyether soft segment and aromatic hard segments. Mechanisms were built on the analysis of material submitted to irradiations of simulation (high energy electrons and gamma radiation) by FTIR spectroscopy and gaseous and liquid degradation products by gas mass spectrometry and size exclusion chromatography. The electron paramagnetic resonance study of radical process and the determination of oxygen consumption and gas formation radiolytic yields allowed us to acquire kinetic data and to estimate dose rate and high doses effects. The polyurethane radio-oxidation mainly concerns soft segments and induced cross-linkings and production by scissions of oxidised compounds (esters, alcohols, carboxylic acids). The kinetic of radical termination is rapid and the dose rate effect is limited. After 10 MGy, branching and scission reactions are in equilibrium and low molecular weight products accumulate. At last, the degradation products release in water is influenced by the oxidation rate and the temperature. After 10 MGy, the soluble fraction is stabilised at 25%. The water soluble products identified by electro-spray ionisation mass spectrometry (alcohols, aldehydes, carboxylic acids) potentially formed complexes with radionuclides. (author)

  9. Electrochemical and Optical Properties of Magnesium-Alloy Hydrides Reviewed

    Directory of Open Access Journals (Sweden)

    Thirugnasambandam G. Manivasagam

    2012-10-01

    Full Text Available As potential hydrogen storage media, magnesium based hydrides have been systematically studied in order to improve reversibility, storage capacity, kinetics and thermodynamics. The present article deals with the electrochemical and optical properties of Mg alloy hydrides. Electrochemical hydrogenation, compared to conventional gas phase hydrogen loading, provides precise control with only moderate reaction conditions. Interestingly, the alloy composition determines the crystallographic nature of the metal-hydride: a structural change is induced from rutile to fluorite at 80 at.% of Mg in Mg-TM alloy, with ensuing improved hydrogen mobility and storage capacity. So far, 6 wt.% (equivalent to 1600 mAh/g of reversibly stored hydrogen in MgyTM(1-yHx (TM: Sc, Ti has been reported. Thin film forms of these metal-hydrides reveal interesting electrochromic properties as a function of hydrogen content. Optical switching occurs during (dehydrogenation between the reflective metal and the transparent metal hydride states. The chronological sequence of the optical improvements in optically active metal hydrides starts with the rare earth systems (YHx, followed by Mg rare earth alloy hydrides (MgyGd(1-yHx and concludes with Mg transition metal hydrides (MgyTM(1-yHx. In-situ optical characterization of gradient thin films during (dehydrogenation, denoted as hydrogenography, enables the monitoring of alloy composition gradients simultaneously.

  10. Assessment of dose in thyroid and salivary glands in dental radiology using thermoluminescent dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Mantuano, Natalia de O.; Silva, Ademir X. da [Instituto Alberto Luiz Coimbra de Pos-Graduacao e Pesquisa em Engenharia (PEN/COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Nuclear; Canevaro, Luca V.; Mauricio, Claudia Lucia P. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ) Rio de Janeiro, RJ (Brazil); Correa, Samanda C.A., E-mail: scorrea@cnen.gov.b [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    Radiobiological and epidemiological studies have provided evidence of risk of salivary and thyroid glands tumors incidence associated with oral radiology. Based on these studies, the tissue weighting factors were reviewed by the International Commission on Radiological Protection (ICRP) in 2007. The main objective of the present work is to estimate the absorbed dose on thyroid and salivary glands (parotid, submandibular and sublingual), during a complete periapical examination. The complete periapical examination was simulated using a Spectro 70X Seletronic X-ray dental equipment on an Alderson Rando phantom with Harshaw LiF:Mg,Ti thermoluminescent dosemeters (TLD100). A PTW DIADOS dosimetric system was used for calibration. The TLD100 were inserted into the phantom slices corresponding to the organs of interest. During a complete periapical examination, the highest evaluated mean absorbed dose was 4.9 mGy in the right submandibular gland and the lowest one of 1.5 mGy in the left thyroid lobe. Entrance surface doses ranged from 2.1 to 2.6 mGy, measured, respectively, for the techniques of upper left molar and lower right molar. When compared with the diagnostic reference levels (DRL), the entrance surface doses values were lower than the DRLs recommended in Brazilian current legislation. However, the dosimetric results show the need of optimization for complete periapical examination to minimize patient exposure. Measurements were performed without the use of thyroid protectors. The use of this device is certainly an easy and simple method of dose reduction. (author)

  11. Quiet-Sun imaging asymmetries in NaI D1 compared with other strong Fraunhofer lines

    CERN Document Server

    Rutten, R J; van der Voort, L H M Rouppe; de Wijn, A G; Carlsson, M; Hansteen, V

    2011-01-01

    Imaging spectroscopy of the solar atmosphere using the NaI D1 line yields marked asymmetry between the blue and red line wings: sampling a quiet-Sun area in the blue wing displays reversed granulation, whereas sampling in the red wing displays normal granulation. The MgI b2 line of comparable strength does not show this asymmetry, nor does the stronger CaII 8542 line. We demonstrate the phenomenon with near-simultaneous spectral images in NaI D1, MgI b2, and CaII 8542 from the Swedish 1-m Solar Telescope. We then explain it with line-formation insights from classical 1D modeling and with a 3D magnetohydrodynamical simulation combined with NLTE spectral line synthesis that permits detailed comparison with the observations in a common format. The cause of the imaging asymmetry is the combination of correlations between intensity and Dopplershift modulation in granular overshoot and the sensitivity to these of the steep profile flanks of the NaI D1 line. The MgI b2 line has similar core formation but much wider ...

  12. Evaluation of the fetal dose during prophylactic placement of internal iliac artery balloon occlusion catheters in placenta accreta

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Sik [Dept. of Radiology, Gachon University Gil hospital, Incheon (Korea, Republic of); Ahn, Sung Min [Dept. of Radiological Science, Gachon University, Incheon (Korea, Republic of)

    2016-09-15

    Placenta accrete patients whose mother mortality rates are rather high due to massive bleeding during childbirth need to have Prophylactic placement of Internal Iliac Artery Balloon Occlusion Catheters procedure to reduce amount of blood loss and inoperative transfusion. Nevertheless, studies for mothers inevitably exposed to dose during PIIABOCs procedure have not been published many yet. Therefore, this study is to investigate exact information on radiation dose exposed to fetus during PIIABOCs procedure. Average effective dose of fetus per organ is 2.38∼8.83 mGy, measured highest at beam center and followed by eyeball, stomach and bladder. The result showed that the longer fluoroscopy time is used, the closer beam center is and the thicker abdominal thickness is, the more effective dose on fetus is increasing. When using the collimator and protection shown to decrease the effective dose and when using higher the patient table shown to decrease the effective dose. It has been reported that the threshold of deterministic effect is about 100mGy. Deterministic effect was regarded as a factor that would influence on fetus exposed by medical radiation than stochastic effect. Consequently, it concluded that dose exposed on fetus in PIIABOCs procedure was approximately 10% of threshold of deterministic effect with effective dose of 0.49∼18.27 mGy.

  13. Product estimate of air kerma-area and the air kerma in the input surface of the skin of pediatric patients undergoing chest X-ray; Estimativa do produto kerma ar-area e do kerma ar na superficie de entrada da pele de pacientes pediatricos submetidos a radiografia de torax

    Energy Technology Data Exchange (ETDEWEB)

    Villa-Chan, Beatriz; Carvalho, Aline; Andrade, Marcos Ely A.; Barros, Vinicius S.M. de; Khoury, Helen J., E-mail: beatrizvillachan@gmail.com, E-mail: alinecx90@gmail.com, E-mail: marcos.ely@gmail.com, E-mail: vsmdbarros@gmail.com, E-mail: hjkhoury@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

    2014-07-01

    The aim of this paper is to evaluate the entrance air kerma (Ka,e) and the product air kerma-area (Pka) for chest examinations performed with pediatric patients in a large public hospital of Recife. For this study 89 examinations of patient with ages from zero to 10 years old were evaluated. The results showed that the mean Ka,e values, for patients of 0-1 years old, 1-5 years old and 5-10 years old, were, respectively, 100 mGy, 120 mGy and 100 mGy. The Pka values for newborn patients range from 11,9 to 58,4 mGy.cm{sup 2}, for patients with 1 to 5 years old range from 17 to 192 mGy.cm{sup 2}, and from 30,4 to 136,2 mGy.cm{sup 2} for patients with ages from 5 to 10 years old. The differences in the Pka values are due the different dimensions of the radiation field. For the results its possible to conclude that the Pka values are high, in special for patients with ages from 1 to 5 years old, indicating that the collimation of the radiation field is not adequate. (author)

  14. An ultra-high dose of electron radiation response of Germanium Flat Fiber and TLD-100

    Science.gov (United States)

    Alawiah, A.; Amin, Y. M.; Abdul-Rashid, H. A.; Abdullah, W. S. Wan; Maah, M. J.; Bradley, D. A.

    2017-01-01

    The thermoluminescence (TL) response of Germanium Flat Fiber (GFF) and TLD-100 irradiated with 2.5 MeV electrons for the doses up to 1 MGy were studied and compared. The aim was to evaluate the TL supralinearity response at an ultra-high dose (UHD) range and to investigate the change in kinetic parameters of the glow peaks, as the doses increases up to 1 MGy. It is found that the critical dose limit (CDL) of GFF is 5 times higher as compared to TLD-100. CDL is determined by the dose at the maximum supralinearity, f(D)max. It is also found that annealing the TLD-100 and GFF with temperature more than 400 °C is required to reset it back to its original condition, following radiation doses up to 1 MGy. It is also noticed the strange behavior of Peak 4 (TLD-100), which tends to be invisible at the lower dose (<10 kGy) and starts to be appeared at the critical dose limit of 10 kGy. This result might be an important clue to understand the behavior of TLD-100 at extremely high dose range. For both samples, it is observed that the TL intensity is not saturated within the UHD range studied.

  15. MgCl2·4((CH3)2CHCH2OH): a new molecular adduct for the preparation of TiCl(x)/MgCl2 catalyst for olefin polymerization.

    Science.gov (United States)

    Thushara, K S; Gnanakumar, Edwin S; Mathew, Renny; Ajithkumar, T G; Rajamohanan, P R; Bhaduri, Sumit; Gopinath, Chinnakonda S

    2012-10-07

    A new molecular adduct of MgCl(2) with isobutanol, namely MgCl(2)·4((CH(3))(2)CHCH(2)OH) (MgiBOH), has been prepared as a precursor to the supporting material for an olefin polymerization catalyst. The MgiBOH adduct and final titanated Ziegler-Natta catalysts have been thoroughly characterized by powder XRD, thermal analysis, Raman spectroscopy and solid-state NMR for structural and spectroscopy aspects. A peak observed at 712 cm(-1) in the Raman spectra of MgiBOH indicates the characteristic Mg-O(6) breathing mode and the formation of the adduct. The diffraction feature at 2θ = 7.8° (d = 11.223 Å) in the XRD confirms the adduct formation and the layered structure. The aim of the present article is to study how the insertion of a bulky isobutanol moiety affects the structural and electronic properties of the MgCl(2)·isobutanol molecular adduct. Indeed, the focus of the present study is to explore how the presence of isobutanol, in the initial molecular adduct, influences the final Z-N catalyst properties and its activity.

  16. Increasing antiplaque/antigingivitis efficacy of an essential oil mouthrinse over time: an in vivo study.

    Science.gov (United States)

    Charles, Christine A; McGuire, J A; Qaqish, James; Amini, Pejmon

    2013-01-01

    This randomized, observer-blind, parallel, controlled study determined the efficacy of an essential oils-containing (EO) antiseptic mouthrinse (in conjunction with toothbrushing) in reducing and/or controlling existing plaque or gingivitis over 6 months. Toothbrushing, combined with placebo rinsing, served as the control (C). Following ethics board approval (Biosci Research Canada, Ltd. Institutional Review Board), 139 healthy adults with mild to moderate plaque and gingivitis were randomized into EO or C groups. All subjects received oral/written instructions, monthly monitoring, and assigned unsupervised rinses. Efficacy variables were whole-mouth mean modified gingival index (MGI), Turesky modification of the Quigley Hein plaque index (PI), bleeding index (BI) at 6, 12, and 24 weeks, and data analysis through an analysis of covariance (ANCOVA) model. The EO group provided greater and increasing MGI, PI, and BI reductions than did C group over all examination periods. Compared to the C group, at 6, 12, and 24 weeks, MGI reductions for the EO group were 4.7%, 9.1%, and 20.4%, and PI reductions were 7.6%, 12.6%, and 26.3%, respectively. BI scores decreased over time and were significant compared to those for the C group (P antiseptic EO rinse can provide a clinically significant benefit in reducing existing plaque and gingivitis.

  17. Estimation of average glandular dose depending on the thickness of the breast; Estimativa da dose glandular media em funcao da espessura da mama

    Energy Technology Data Exchange (ETDEWEB)

    Real, Jessica V.; Luz, Renata M. da, E-mail: jessica.real@pucrs.br, E-mail: renata.luz@pucrs.br [Hospital Sao Lucas (HSL/PUCRS), Porto Alegre, RS (Brazil); Fröhlich, Bruna D.; Pertile, Alessandra S.; Silva, Ana Maria Marques da, E-mail: bruna.frohlich@acad.pucrs.br, E-mail: lessandra.pertile@acad.pucrs.br, E-mail: ana.marques@pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil)

    2014-07-01

    Breast cancer is the most common type of cancer in women worldwide. Mammography is, to date, the most efficient method for detecting an abnormality in the patient's breast. It is a technique of imaging diagnostic that requires special care because radiographs without adequate quality may lead to a false diagnosis and lead to the need for a repeat examination, increasing the dose of radiation in the patient. This study aimed to evaluate the average glandular dose (AGD), depending on the breast thickness in patients undergoing routine tests, with a digital computer radiography processing system. Analyzed 30 exhibitions in patients aged (65 ± 12) years, in the right and left caudal skull projections, for breasts with thicknesses between 45 mm and 50 mm. The calculated value of the AGD for this track thickness was (1.600 ± 0.009) mGy. The performance of mammography quality control tests was satisfactory and the AGD values obtained for the chosen thickness range is acceptable, since the threshold achievable is 1.6 mGy and the acceptable is 2 mGy. In Brazil, it is only required the input dose calculation in skin for 45 mm breasts. However, the calculation of AGD is required for different thicknesses of the breast, to identify the best mammographic pattern aiming at better image quality at the lowest dose provided the patient.

  18. Measurement of eye lens dose for Varian On-Board Imaging with different cone-beam computed tomography acquisition techniques.

    Science.gov (United States)

    Deshpande, Sudesh; Dhote, Deepak; Thakur, Kalpna; Pawar, Amol; Kumar, Rajesh; Kumar, Munish; Kulkarni, M S; Sharma, S D; Kannan, V

    2016-01-01

    The objective of this work was to measure patient eye lens dose for different cone-beam computed tomography (CBCT) acquisition protocols of Varian's On-Board Imaging (OBI) system using optically stimulated luminescence dosimeter (OSLD) and to study the variation in eye lens dose with patient geometry and distance of isocenter to the eye lens. During the experimental measurements, OSLD was placed on the patient between the eyebrows of both eyes in line of nose during CBCT image acquisition to measure eye lens doses. The eye lens dose measurements were carried out for three different cone-beam acquisition protocols (standard dose head, low-dose head [LDH], and high-quality head [HQH]) of Varian OBI. Measured doses were correlated with patient geometry and distance between isocenter and eye lens. Measured eye lens doses for standard head and HQH protocols were in the range of 1.8-3.2 mGy and 4.5-9.9 mGy, respectively. However, the measured eye lens dose for the LDH protocol was in the range of 0.3-0.7 mGy. The measured data indicate that eye lens dose to patient depends on the selected imaging protocol. It was also observed that eye lens dose does not depend on patient geometry but strongly depends on distance between eye lens and treatment field isocenter. However, undoubted advantages of imaging system should not be counterbalanced by inappropriate selection of imaging protocol, especially for very intense imaging protocol.

  19. Comparative analysis of doses to aquatic biota in water bodies impacted by radioactive contamination.

    Science.gov (United States)

    Kryshev, A I; Sazykina, T G

    2012-06-01

    Comparative analysis of doses to the reference species of freshwater biota was performed for the following water bodies in Russia or former USSR: Chernobyl NPPs cooling pond, Lakes Uruskul and Berdenish located in the Eastern Urals Radioactive Trace, Techa River, Yenisei River. It was concluded that the doses to biota were considerably different in the acute and chronic periods of radioactive contamination. The most vulnerable part of all considered aquatic ecosystems was benthic trophic chain. A numerical scale on the "dose rate - effects" relationships for fish was formulated. Threshold dose rates above which radiation effects can be expected in fish were evaluated to be the following: 1 mGy d(-1) for appearance of the first morbidity effects in fish; 5 mGy d(-1) for the first negative effects on reproduction system; 10 mGy d(-1) for the first effects on life shortening of fish. The results of dose assessment to biota were compared with the scale "dose rate - effects" and the literature data on the radiobiological effects observed in the considered water bodies. It was shown that in the most contaminated water bodies the dose rates were high enough to cause the radiobiological effects in fish. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Radiation Effects on Polypropylene Carbon Nanofibers

    Science.gov (United States)

    Hamilton, John; Mion, Thomas; Chipara, Alin C.; Ibrahim, Elamin I.; Lozano, Karen; Chipara, Magdalena; Tidrow, Steven C.; Chipara, Mircea

    2010-03-01

    Dispersion of carbon nanostructures within polymeric matrices affects most physical and chemical properties of the polymeric matrix (increased Young modulus, improved thermal stability, faster crystallization rates, higher equilibrium degree of crystallinity, modified glass, melting, and crystallization temperatures, enhanced thermal and electrical conductivity). Such changes have been reported and explained by thorough spectroscopic investigations. Nevertheless, little is known about the radiation stability of such nanocomposites. The research is focused on spectroscopic investigations of radiation-induced modifications in isotactic polypropylene (iPP)-vapor grown nanofiber (VGCNF)composites. VGCNF were dispersed within iPP by extrusion at 180^oC. Composites containing various amounts of VGCNFs ranging from 0 to 20 % wt. were prepared and subjected to gamma irradiation, at room temperature, at various integral doses (10 MGy, 20 MGy, and 30 MGy). Raman spectroscopy, ATR, and WAXS were used to assess the radiation-induced modifications in these nanocomposites. Acknowledgements: This research was supported by the Welch Foundation (Department of Chemistry at UTPA) and by US Army Research Office (AMSRD-ARL-RO-SI: 54498-MS-ISP).

  1. Radiation Effects on Polypropylene Carbon Nanofibers Composites: Spectroscopic Investigations

    Science.gov (United States)

    Hamilton, John; Mion, Thomas; Cristian Chipara, Alin; Ibrahim, Elamin I.; Lozano, Karen; Tidrow, Steven; Magdalena Chipara, Dorina; Chipara, Mircea

    2010-03-01

    Dispersion of carbon nanostructures within polymeric matrices affects their physical and chemical properties (increased Young modulus, improved thermal stability, faster crystallization rates, higher equilibrium degree of crystallinity, modified glass, melting, and crystallization temperatures, enhanced thermal and electrical conductivity). Nevertheless, little is known about the radiation stability of such nanocomposites. The research is focused on spectroscopic investigations of radiation-induced modifications in isotactic polypropylene (iPP)-vapor grown nanofiber (VGCNF) composites. VGCNF were dispersed within iPP by extrusion at 180^oC. Composites containing various amounts of VGCNFs ranging from 0 to 20 % wt. were prepared and subjected to gamma irradiation, at room temperature, at various integral doses (10 MGy, 20 MGy, and 30 MGy). Raman spectroscopy, ATR, and WAXS were used to assess the radiation-induced modifications in these nanocomposites. Acknowledgements: This research was supported by the Welch Foundation (Department of Chemistry at UTPA), by Air Force Research Laboratory (FA8650-07-2-5061) and by US Army Research Laboratory/Office (W911NF-08-1-0353).

  2. Suggestion of the manual exposure condition guideline for reducing patient dose in digital breast tomosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Eun Ae [Dept. of Radiology, Korea University Guro Hospital, Seoul (Korea, Republic of); Lee, In Ja [Dept. of Radiologic Technology, Dongnam Health University, Suwon (Korea, Republic of)

    2016-12-15

    The conditions after exposure to digital mammography and digital breast tomosynthesis were analyzed. The examinations for the ACR phantom were done using manual exposure, not auto exposure, to examine image discrimination and patient dose. As a result, the following results were derived: In the CC exposure , the kVp was 2kVp higher while mAs decreased to 58.6% for the 3D tomography. Such result showed an approximate decrease of 60mAs. At that time, the patients Average Glandular Dose (AGD) was 1.65mGy in 2D and 1.87mGy in 3D; thus, AGD of 3D was shown to have about 1.13 times higher. The result of the manual exposure revealed a reduced mAs of up to 80%; there was no effect in the assessment standard in terms of image discrimination, resulting in more than 10 points. When mAs was reduced to 80% in the manual exposure for ACR phantom, AGD was decreased to 0.66mGy. The diagnostic values of images were maintained and patients dose was reduced in the manual exposure in the AEC condition for 3D. Since the use of 3D has recently increased, using the manual exposure has been recommended in this study to improve the diagnostic value, while, simultaneously reducing patients dose.

  3. Radio-photoluminescence of highly irradiated LiF:Mg,Ti and LiF:Mg,Cu,P detectors

    CERN Document Server

    Mrozik, Anna; Marczewska, Barbara; Obryk, Barbara; Hodyr, Krzysztof; Gieszczyk, Wojciech

    2014-01-01

    The radio-photoluminescent (RPL) characteristics of LiF:Mg,Ti (MTS) and LiF:Mg,Cu,P (MCP) thermoluminescent detectors, routinely used in radiation protection dosimetry, were investigated after irradiation with ultra-high electron doses ranging up to 1 MGy. The photoluminescence of both types of LiF detectors was stimulated by a blue light (460 nm) and measured within a spectral window around 530 nm. The RPL dose response was found to be linear up to 50 kGy and sublinear in the range of 50 kGy to 1 MGy for MCP detectors and linear up to 3 kGy and next sublinear in the range from 5 kGy to 1 MGy for MTS detectors. For both type of LiF detectors RPL signal is saturated for doses higher than 100 kGy. The observed differences between MCP and MTS may suggest, that the RPL effect in LiF is not entirely governed by intrinsic defects (F2 and F3+ centers), but impurities may also have a significant influence. Due to the non-destructive character of the RPL measurement, it is suggested to apply combined RPL/TL readouts, ...

  4. Should we educate care staff to improve the oral health and oral hygiene of people with intellectual disability in residential care? Real world lessons from a randomized controlled trial.

    Science.gov (United States)

    Mac Giolla Phadraig, Caoimhin; Guerin, Suzanne; Nunn, June

    2015-01-01

    This study assessed the impact of a multitiered oral health educational program on the oral health and oral hygiene of people with intellectual disabilities (ID). In a controlled pretest, posttest trial, with cluster randomization, a pyramidal training program was delivered to residential staff who cared for a randomly allocated, purposively stratified intervention group of people with ID living in community care homes. A control group lived in centers where staff received no training. Clinical measures were carried out pre- and posttest. Difference in Modified Gingival Index (MGI) and Plaque Index (PI) was measured posttest using ANCOVA. Seventy-six participants took part, representing 49.0% of the invited sample (n = 155). Fourteen did not receive clinical examination. There was one dropout 6-9 months later. A 10.5% and 8.5% reduction in mean MGI and PI was evident at posttest but did not show statistically significant difference, when controlling for baseline covariates (p > 0.05, ANCOVA). Mean MGI and PI scores were not significantly different among people with ID whose care staff had and had not received oral health training. Limitations are discussed. The results indicate that this program failed to significantly improve oral health or oral hygiene, despite the intervention being "educationally" successful. More research is needed.

  5. Thyroid doses and risk to paediatric patients undergoing neck CT examinations

    Energy Technology Data Exchange (ETDEWEB)

    Spampinato, Maria Vittoria; Tipnis, Sameer; Huda, Walter [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Tavernier, Joshua [Medical University of South Carolina, College of Medicine, Charleston, SC (United States)

    2015-07-15

    To estimate thyroid doses and cancer risk for paediatric patients undergoing neck computed tomography (CT). We used average CTDI{sub vol} (mGy) values from 75 paediatric neck CT examinations to estimate thyroid dose in a mathematical anthropomorphic phantom (ImPACT Patient CT Dosimetry Calculator). Patient dose was estimated by modelling the neck as mass equivalent water cylinder. A patient size correction factor was obtained using published relative dose data as a function of water cylinder size. Additional correction factors included scan length and radiation intensity variation secondary to tube-current modulation. The mean water cylinder diameter that modelled the neck was 14 ± 3.5 cm. The mathematical anthropomorphic phantom has a 16.5-cm neck, and for a constant CT exposure, would have thyroid doses that are 13-17 % lower than the average paediatric patient. CTDI{sub vol} was independent of age and sex. The average thyroid doses were 31 ± 18 mGy (males) and 34 ± 15 mGy (females). Thyroid cancer incidence risk was highest for infant females (0.2 %), lowest for teenage males (0.01 %). Estimated absorbed thyroid doses in paediatric neck CT did not significantly vary with age and gender. However, the corresponding thyroid cancer risk is determined by gender and age. (orig.)

  6. Real-time eye lens dose monitoring during cerebral angiography procedures

    Energy Technology Data Exchange (ETDEWEB)

    Safari, M.J.; Wong, J.H.D.; Kadir, K.A.A.; Ng, K.H. [University of Malaya, Department of Biomedical Imaging, Faculty of Medicine, Kuala Lumpur (Malaysia); University of Malaya, University of Malaya Research Imaging Centre (UMRIC), Faculty of Medicine, Kuala Lumpur (Malaysia); Thorpe, N.K.; Cutajar, D.L.; Petasecca, M.; Lerch, M.L.F.; Rosenfeld, A.B. [University of Wollongong, Centre for Medical Radiation Physics (CMRP), Wollongong, NSW (Australia)

    2016-01-15

    To develop a real-time dose-monitoring system to measure the patient's eye lens dose during neuro-interventional procedures. Radiation dose received at left outer canthus (LOC) and left eyelid (LE) were measured using Metal-Oxide-Semiconductor Field-Effect Transistor dosimeters on 35 patients who underwent diagnostic or cerebral embolization procedures. The radiation dose received at the LOC region was significantly higher than the dose received by the LE. The maximum eye lens dose of 1492 mGy was measured at LOC region for an AVM case, followed by 907 mGy for an aneurysm case and 665 mGy for a diagnostic angiography procedure. Strong correlations (shown as R{sup 2}) were observed between kerma-area-product and measured eye doses (LOC: 0.78, LE: 0.68). Lateral and frontal air-kerma showed strong correlations with measured dose at LOC (AK{sub L}: 0.93, AK{sub F}: 0.78) and a weak correlation with measured dose at LE. A moderate correlation was observed between fluoroscopic time and dose measured at LE and LOC regions. The MOSkin dose-monitoring system represents a new tool enabling real-time monitoring of eye lens dose during neuro-interventional procedures. This system can provide interventionalists with information needed to adjust the clinical procedure to control the patient's dose. (orig.)

  7. Investigation of breast dose in five screening mammography centres in Greece

    Energy Technology Data Exchange (ETDEWEB)

    Tsapaki, V [Medical Physics Department, Konstantopoulio Hospital, Nea Ionia, 142 33, Athens (Greece); Tsalafoutas, I A [Medical Physics Department, Agios Savvas Hospital, 171 Alexandras Avenue, 115 22, Athens (Greece); Poga, V; Louizi, A; Kottou, S [Medical Physics Department, Medical School, Athens University, University of Athens, 75 Mikras Asias, 115 27, Athens (Greece); Koulentianos, E [Radiology Department, Konstantopoulio Hospital, Nea Ionia, 142 33, Athens (Greece)

    2008-09-01

    The objectives of this study were to investigate the techniques currently used for screening mammography in Greece, to estimate the mean glandular dose (MGD) for establishing a baseline radiation dose database, to analyse the effects of various factors on MGD, and to compare the results with others in the literature. Five mammographic facilities and 250 women having as a routine screening mammogram one craniocaudal (CC) and one mediolateral oblique (MLO) projection in each breast were included in the study. The parameters recorded were age, weight, compressed breast thickness (CBT), tube potential (kV), tube loading (mA s) and MLO projection angle. Large differences were observed among the different mammography facilities, mainly in terms of the tube potential setting and the MLO angle used. The average MGD per exposure was 1.4 {+-} 0.6 mGy while the respective averages separately for the CC and MLO projections were 1.2 {+-} 0.5 and 1.5 {+-} 0.7 mGy, respectively. The average MGD values recorded in this study were below the limit of 2 mGy established for the reference medium-sized breast of 4.5 cm CBT. However, the variety of techniques observed revealed the need for a nationwide survey concerning screening mammography in Greece.

  8. The radiolysis of lithium oxide ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Tiliks, J.; Supe, A.; Kizane, G.; Tiliks, J. Jr. [Latvia Univ., Riga (Latvia). Dept. of Chemistry; Grishmanov, V.; Tanaka, S.

    1998-03-01

    The radiolysis of Li{sub 2}O ceramics exposed to accelerated electrons (5 MeV) at 380 K was studied in the range of high absorbed doses up to 250 MGy. The formation of radiation defects (RD) and radiolysis products (RP) was demonstrated to occur simultaneously in the regions of (1) the regular crystalline lattice and (2) an enhanced content of the intrinsic defects and impurities. The production of the electronic RD and RP is more efficient in the region of the defected lattice than that at the site of the regular crystalline lattice. However, the stability of RD and RP formed in the region of the intrinsic defects is far less than those produced at the crystalline lattice, since most of the first mentioned RD and RP disappears with irradiation dose due to the radiation stimulated recombination. By this means the enhanced quantity of RD and RP is localized in the Li{sub 2}O ceramics irradiated to absorbed dose of 40-50 MGy, and hence this can influence the tritium release parameters. As soon as the intrinsic defects have been consumed in the production of RD and RP and the recombination of unstable electronic RD and RP takes place (at dose of {approx}100 MGy), the radiolysis of Li{sub 2}O ceramics occurs only at the crystalline lattice. Furthermore, the concentration of RD and RP increases monotonically and tends to the steady-state level. (author)

  9. Trends and Issues in Distance Education: International Perspectives

    Directory of Open Access Journals (Sweden)

    Erhan EROGLU

    2006-04-01

    Full Text Available Trends and Issues in Distance Education: International Perspectives Edited by Yusra Laila Visser, Lya Visser, Michael Simonsın, & Ray Amirault, 2005, United States of America: Information Age Publishing, Inc. pp. 315. ISBN 1-59311-212-2 Reviewed by Dr. Erhan EROGLU Anadolu University Eskisehir, TURKEY In this book, the terms of “distance education” has been discussed from different perspectives. The term “distance education” conjures up in many minds the image of modern, computer-enabled technology that has blossomed in only the last twenty years. Many of the lessons learned over the last century of distance education research and practice have been implemented in a wide variety of distance education programs worldwide, from higher education online learning programs in the United States to rural, radio-based instructional programs in developing countries. Distance education is truly international discipline. While it is true that the term “distance education” has a universal definiton, local distance ducation experiences are often quite idiosyncratic. This idiosyncratic nature emerges from the need to integrate distance education within the constraints, oppurtunities, and realities of spesific cultural and geographic contexts. From these local distance education experiences, educators are developing new understandings of the broader field of distance education, including the trends and issues present in the field. ORGANIZATION OF THE SECTIONS This book has been organized by thematic content into four main sections. Each of these sections represents a unique level of analysis for trends and issues in distance education. Part I presents five distinct perspectives on the state of distance education and the trends and issues of the field. First perspective of five distinct perpectives is “a survey of progressive and conservative trends in education with implications for distance education practice.” Second perspective is

  10. A methodology for on-board CBCT imaging dose using optically stimulated luminescence detectors.

    Science.gov (United States)

    Mail, Noor; Yusuf, Muhammad; Alothmany, Nazeeh; Kinsara, A Abdulrahman; Abdulkhaliq, Fahad; Ghamdi, Suliman M; Saoudi, Abdelhamid

    2016-09-08

    Cone-beam computed tomography CBCT systems are used in radiation therapy for patient alignment and positioning. The CBCT imaging procedure for patient setup adds substantial radiation dose to patient's normal tissue. This study pre-sents a complete procedure for the CBCT dosimetry using the InLight optically-stimulated-luminescence (OSL) nanoDots. We report five dose parameters: the mean slice dose (DMSD); the cone beam dose index (CBDIW); the mean volume dose (DMVD); point-dose profile, D(FOV); and the off-field Dose. In addition, CBCT skin doses for seven pelvic tumor patients are reported. CBCT-dose mea-surement was performed on a custom-made cylindrical acrylic body phantom (50cm length, 32cm diameter). We machined 25 circular disks (2 cm thick) with grooves and holes to hold OSL-nanoDots. OSLs that showed similar sensitivities were selected and calibrated against a Farmer-type ionization-chamber (0.6 CT) before being inserted into the grooves and holes. For the phantom scan, a standard CBCT-imaging protocol (pelvic sites: 125 kVp, 80 mA and 25 ms) was used. Five dose parameters were quantified: DMSD, CBDIW, DMVD, D(FOV), and the off-field dose. The DMSD for the central slice was 31.1 ± 0.85 mGy, and CBDIW was 34.5± 0.6 mGy at 16cm FOV. The DMVD was 25.6 ± 1.1 mGy. The off-field dose was 10.5 mGy. For patients, the anterior and lateral skin doses attributable to CBCT imaging were 39.04 ± 4.4 and 27.1 ± 1.3 mGy, respectively.OSL nanoDots were convenient to use in measuring CBCT dose. The method of selecting the nanoDots greatly reduced uncertainty in the OSL measurements. Our detailed calibration procedure and CBCT dose measurements and calculations could prove useful in developing OSL routines for CBCT quality assessment, which in turn gives them the property of high spatial resolution, meaning that they have the potential for measurement of dose in regions of severe dose-gradients.

  11. 低剂量辐射对环磷酰胺化疗毒性作用的影响%Effects of low dose pre-irradiation on the toxicity of cyclophosphamide

    Institute of Scientific and Technical Information of China (English)

    Hongsheng Yu; Li Yu; Aiqin Song; Zimin Liu; Yeling Zhang; Xinjia He

    2011-01-01

    Objective:The aim of the study was to investigate the effects as well as the possible mechanisms of low dose y-ray pre-irradiation on hepatic damage, DNA damage of peripheral lymphocytes and genetic material damage caused by high dosage of cyclophosphamide (CTX). Methods: Kunming strain male mice were randomly divided into five groups:control group, sham-irradiated group, low dose irradiation group (LDR group), cyclophosphamide chemotherapy group (CTX group) and low close irradiation combined with chemotherapy group (LDR + CTX group). Having being raised for one week,all the mice were implanted subcutaneously with S180 cells in the left inguen (control group excluded). On days 8 and 11,mice of LDR and LDR + CTX groups were given 75 mGy whole-body y-irradiation, 30 h later mice of CTX and LDR + CTX groups were injected I.p. 3.0 mg cyclophosphamide. All the mice were sacrificed on day 13. DNA damage of the peripheral lymphocytes was analyzed using single cell gel electrophoresis (SCGE); ALT activity, total protein (TP) and albumin (ALB)of the plasma were analyzed using automatic biochemistry analyzer; MDA content, SOD and GSH-PX activity of the hepatic homogenate were analyzed using chromometry; genetic material damage was analyzed using micronucleus frequency (MNF)of polychromatoerythrocytes (PCE) in bone marrow. Results: 1. Differences of MDA contents, SOD and GSH-PX activity of hepatic homogenate between 5 groups had notable statistical significance (P 0.05). Differences of TP and ALB of plasma between 5 groups had statistical sig-nificance (F = 12.879 and 6.336 respectively, P 0.05). Conclusion:1. CTX can damage the hepatic tissue through oxidative stress; 75 mGy y-irradiation before CTX chemotherapy can induce activities of anti-oxidative enzymes, promote elimination of free radicals, so as to alleviate the damaging effects of oxidative stress to hepatic tissue caused by high-close chemotherapy. 2. A 75 mGy y-irradiation before CTX chemotherapy has no obvious

  12. Investigating the low-dose limits of multidetector CT in lung nodule surveillance.

    Science.gov (United States)

    Paul, N S; Siewerdsen, J H; Patsios, D; Chung, T B

    2007-09-01

    The purpose of this study was to evaluate the factors limiting nodule detection in thoracic computed tomography (CT) and to determine whether prior knowledge of nodule size and attenuation, available from a baseline CT study, influences the minimum radiation dose at which nodule surveillance CT scans can be performed while maintaining current levels of nodule detectability. Multiple nodules varying in attenuation (-509 to + 110 HU) and diameter (1.6 to 9.5 mm) were layered in random and ordered sequences within 2 lung cylinders made of Rando lung material and suspended within a custom-built CT phantom. Multiple CT scans were performed at varying kVp (120, 100, and 80), mA (200, 150, 100, 50, 20, and 10), and beam collimation (5, 2.5, and 1.25 mm) on a four-row multidetector scanner (Lightspeed, General Electric, Milwaukee, WI) using 0.8 s gantry rotation. The corresponding range of radiation dose over which images were acquired was 0.3-26.4 mGy. Nine observers independently performed three specific tasks, namely: (1) To detect a 3.2 mm nodule of 23 HU; (2) To detect 3.2 mm nodules of varying attenuation (-509 to -154 HU); and (3) To detect nodules varying in size (1.6-9 mm) and attenuation (-509 to 110 HU). A two-alternative forced-choice test was used in order to determine the limits of nodule detection in terms of the proportion of correct responses (Pcorr, related to the area under the ROC curve) as a summary metric of observer performance. The radiation dose levels for detection of 99% of nodules in each task were as follows: Task 1 (1 mGy); Task 2 (5 mGy); and Task 3 (7 mGy). The corresponding interobserver confidence limits were 1, 5, and 10 mGy for Tasks 1, 2, and 3, respectively. There was a fivefold increase in the radiation dose required for detection of lower-density nodules (Tasks 1 to 2). Absence of prior knowledge of the nodule size and density (Task 3) corresponds to a significant increase in the minimum required radiation dose. Significant image

  13. Low-Dose Gamma Radiation Does Not Induce an Adaptive Response for Micronucleus Induction in Mouse Splenocytes.

    Science.gov (United States)

    Bannister, L A; Serran, M L; Mantha, R R

    2015-11-01

    Low-dose ionizing radiation is known to induce radioadaptive responses in cells in vitro as well as in mice in vivo. Low-dose radiation decreases the incidence and increases latency for spontaneous and radiation-induced tumors in mice, potentially as a result of enhanced cellular DNA repair efficiency or a reduction in genomic instability. In this study, the cytokinesis-block micronucleus (CBMN) assay was used to examine dose response and potential radioadaptive response for cytogenetic damage and cell survival in C57BL/6 and BALB/c spleen cells exposed in vitro or in vivo to low-dose 60Co gamma radiation. The effects of genetic background, radiation dose and dose rate, sampling time and cell cycle were investigated with respect to dose response and radioadaptive response. In C57BL/6 mice, a linear-quadratic dose-response relationship for the induction of micronuclei (MN) was observed for doses between 100 mGy and 2 Gy. BALB/c mice exhibited increased radiosensitivity for MN induction compared to C57BL/6 mice. A 20 mGy dose had no effect on MN frequencies in splenocytes of either mouse strain, however, increased spleen weight and a reduced number of dead cells were noted in the C57BL/6 strain only. Multiple experimental parameters were investigated in radioadaptive response studies, including dose and dose rate of the priming dose (20 mGy at 0.5 mGy/min and 100 mGy at 10 mGy/min), time interval (4 and 24 h) between priming and challenge doses, cell cycle stage (resting or proliferating) at exposure and kinetics after the challenge dose. Radioadaptive responses were not observed for MN induction for either mouse strain under any of the experimental conditions investigated. In contrast, a synergistic response for radiation-induced micronuclei in C57BL/6 spleen was detected after in vivo 20 mGy irradiation. This increase in the percentage of cells with cytogenetic damage was associated with a reduction in the number of nonviable spleen cells, suggesting that low

  14. Internal dosimetry of radiopharmaceuticals derived of antitumor polypeptide isolated from venoms: Crotalus durissus terrifucus and Scorpaena plumieri;Dosimetria interna de radiofarmacos derivados de polipeptideos antitumorais isolados dos venenos de: Crotalus durissus terrificus e Scorpaena plumieri

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Henrique Martins de

    2009-07-01

    administration of {sup 131} I-Crtx was 0.01 mGy/370MBq for both intravenous injection and for the intratumoral injection. In tumor, the value was 3.28 mGy/370MBq for intravenous injection and 107.18 mGy/370MBq for intratumoral injection. For the administration of {sup 131}I-SPGP values for the bone marrow were 1.34 mGy/370MBq for intravenous injection and 0.12 mGy/370MBq for intratumoral injection. In tumor, 256.29 mGy/370MBq for intravenous injection and 895.69 mGy/370MBq for intratumoral injection. The results suggest good radiation safety for both radiopharmaceuticals considering the values found for the bone marrow by both intratumoral and intravenous routes, in view of the importance of this body to generate blood cells. The results for the tumor intravenously indicate diagnostic applicability for both molecules. Through intratumoral, the values suggest the feasibility for use of {sup 131}I-Crtx and of {sup 131}I-SPGP as a therapeutic agent, given the persistence of radioactivity in the tumor site. Although {sup 131}I-Crtx has proved to be more secure for applications in diagnosis, its potential for application in internal radiotherapy is lower than that of {sup 131}I-SPGp. Both {sup 131}I-Crtx and {sup 131}I-SPGP, proved to be good prototypes for the development of radiopharmaceuticals. This study indicates that is necessary the synthesis of analogues with lower uptake in healthy organs and a higher tumor uptake, as well as pharmaceutical formulations, using nano technology, such as liposomes, nano-materials for controlled release of drugs. (author)

  15. Application of the optically stimulated luminescence (OSL) technique for mouse dosimetry in micro-CT imaging

    Energy Technology Data Exchange (ETDEWEB)

    Vrigneaud, Jean-Marc; Courteau, Alan; Oudot, Alexandra; Collin, Bertrand [Department of Nuclear Medicine, Centre Georges-François Leclerc, 1 rue Professeur Marion, Dijon 21079 Cedex (France); Ranouil, Julien [Landauer Europe, 33 avenue du Général Leclerc, Fontenay-aux-Roses 92266 Cedex (France); Morgand, Loïc; Raguin, Olivier [Oncodesign, 20 rue Jean Mazen, Dijon 21076 Cedex (France); Walker, Paul [LE2i CNRS UMR 5158, Faculty of Medicine, BP 87900, 21079 Dijon Cedex (France); Brunotte, François [Department of Nuclear Medicine, Centre Georges-François Leclerc, 1 rue Professeur Marion, Dijon 21079 Cedex, France and LE2i CNRS UMR 5158, Faculty of Medicine, BP 87900, 21079 Dijon Cedex (France)

    2013-12-15

    Purpose: Micro-CT is considered to be a powerful tool to investigate various models of disease on anesthetized animals. In longitudinal studies, the radiation dose delivered by the micro-CT to the same animal is a major concern as it could potentially induce spurious effects in experimental results. Optically stimulated luminescence dosimeters (OSLDs) are a relatively new kind of detector used in radiation dosimetry for medical applications. The aim of this work was to assess the dose delivered by the CT component of a micro-SPECT (single-photon emission computed tomography)/CT camera during a typical whole-body mouse study, using commercially available OSLDs based on Al{sub 2}O{sub 3}:C crystals.Methods: CTDI (computed tomography dose index) was measured in micro-CT with a properly calibrated pencil ionization chamber using a rat-like phantom (60 mm in diameter) and a mouse-like phantom (30 mm in diameter). OSLDs were checked for reproducibility and linearity in the range of doses delivered by the micro-CT. Dose measurements obtained with OSLDs were compared to those of the ionization chamber to correct for the radiation quality dependence of OSLDs in the low-kV range. Doses to tissue were then investigated in phantoms and cadavers. A 30 mm diameter phantom, specifically designed to insert OSLDs, was used to assess radiation dose over a typical whole-body mouse imaging study. Eighteen healthy female BALB/c mice weighing 27.1 ± 0.8 g (1 SD) were euthanized for small animal measurements. OLSDs were placed externally or implanted internally in nine different locations by an experienced animal technician. Five commonly used micro-CT protocols were investigated.Results: CTDI measurements were between 78.0 ± 2.1 and 110.7 ± 3.0 mGy for the rat-like phantom and between 169.3 ± 4.6 and 203.6 ± 5.5 mGy for the mouse-like phantom. On average, the displayed CTDI at the operator console was underestimated by 1.19 for the rat-like phantom and 2.36 for the mouse

  16. Low-dose radiation induces endoplasmic reticulum stress and activates PERK-CHOP signaling pathway in mouse testicular cells%低剂量电离辐射诱导小鼠睾丸细胞内质网应激及PERK-CHOP信号通路的激活

    Institute of Scientific and Technical Information of China (English)

    方芳; 龚平生; 宋祥福; 龚守良; 王志成

    2012-01-01

    and the activation of the PERK-CHOP signaling pathway in mouse testicular cells. Methods: Healthy Kunming mice were randomly assigned to time-effect (0,3,6, 12 and 24 h of irradiation at 75 mGy) and dose-effect (12 h of irradiation at 0, 50, 75, 100 and 200 mGy) groups. The contents of H2O2 and MDA were measured by colorimetry with the agent kits, the expressions of GRP78, PERK and CHOP mRNA detected by quantitative RT-PCR, and the levels of GRP78, PERK, phosphorylated PERK (pho-PERK) and CHOP proteins determined by Western blotting and image analysis. Results: After whole-body irradiation of the mice with 75 mGy, the content of H2O2 in the testis tissue was increased with time prolongation, while that of MDA decreased slightly at 3 and 6 h and then increased with the lengthening of time, both increased significantly at 12 and 24 h as compared with those at 0 h (P < 0. 05 , P < 0. 01). Apart from reduced levels of GRP78 mRNA at 3 and 24 h and GRP78 protein at 6 h after irradiation, significant increases were found in the mRNA expressions of GRP78 at 12 h, PERK at 3, 6, 12 and 24 h and CHOP at 12 and 24 h (P < 0.05, P < 0.01) , as well as in the protein levels of GRP78 at 12 and 24 h, pho-PERK at 3 , 12 and 24 h and CHOP at 3 , 6, 12 and 24 h in comparison with those at 0 h (P < 0. 05 , P < 0.01). No obvious regularity was observed in the change of the PERK protein expression. After 12 h of whole-body irradiation, the content of H2O2 was increased at 50, 75 and 100 mGy, but decreased slightly at 200 mGy, while that of MDA was increased with dose increasing, with significant increases in the content of H2O2 at 75 and 100 mGy and in that of MDA at 75 , 100 and 200 mGy as compared with the 0 mGy group. Apart from the reduced levels of GRP78 mRNA at 50 and 200 mGy, significant increases were found in the mRNA expressions of PERK at 75 , 100 and 200 mGy and CHOP at 50, 75 , 100 and 200 ( P < 0. 05 , P < 0. 01) as well as in the protein levels of GRP78 at 100 and 200 mGy

  17. Dose-dependent hepatic transcriptional responses in Atlantic salmon (Salmo salar) exposed to sublethal doses of gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Song, You, E-mail: you.song@niva.no [Norwegian University of Life Sciences (NMBU), Faculty of Environmental Science and Technology, Department of Environmental Sciences (IMV), Centre for Environmental Radioactivity - CERAD, P.O. Box 5003, N-1432 Ås (Norway); Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, N-0349 Oslo (Norway); Salbu, Brit; Teien, Hans-Christian; Heier, Lene Sørlie [Norwegian University of Life Sciences (NMBU), Faculty of Environmental Science and Technology, Department of Environmental Sciences (IMV), Centre for Environmental Radioactivity - CERAD, P.O. Box 5003, N-1432 Ås (Norway); Rosseland, Bjørn Olav [Norwegian University of Life Sciences (NMBU), Faculty of Environmental Science and Technology, Department of Environmental Sciences (IMV), Centre for Environmental Radioactivity - CERAD, P.O. Box 5003, N-1432 Ås (Norway); Norwegian University of Life Sciences (NMBU), Department of Ecology and Natural Resource Management, P.O. Box 5003, N-1432 Ås (Norway); Tollefsen, Knut Erik [Norwegian University of Life Sciences (NMBU), Faculty of Environmental Science and Technology, Department of Environmental Sciences (IMV), Centre for Environmental Radioactivity - CERAD, P.O. Box 5003, N-1432 Ås (Norway); Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, N-0349 Oslo (Norway)

    2014-11-15

    Highlights: • First study on early stress responses in salmon exposed to low-dose gamma radiation. • Dramatic dose-dependent transcriptional responses characterized. • Multiple modes of action proposed for gamma radiation. - Abstract: Due to the production of free radicals, gamma radiation may pose a hazard to living organisms. The high-dose radiation effects have been extensively studied, whereas the ecotoxicity data on low-dose gamma radiation is still limited. The present study was therefore performed using Atlantic salmon (Salmo salar) to characterize effects of low-dose (15, 70 and 280 mGy) gamma radiation after short-term (48 h) exposure. Global transcriptional changes were studied using a combination of high-density oligonucleotide microarrays and quantitative real-time reverse transcription polymerase chain reaction (qPCR). Differentially expressed genes (DEGs; in this article the phrase gene expression is taken as a synonym of gene transcription, although it is acknowledged that gene expression can also be regulated, e.g., at protein stability and translational level) were determined and linked to their biological meanings predicted using both Gene Ontology (GO) and mammalian ortholog-based functional analyses. The plasma glucose level was also measured as a general stress biomarker at the organism level. Results from the microarray analysis revealed a dose-dependent pattern of global transcriptional responses, with 222, 495 and 909 DEGs regulated by 15, 70 and 280 mGy gamma radiation, respectively. Among these DEGs, only 34 were commonly regulated by all radiation doses, whereas the majority of differences were dose-specific. No GO functions were identified at low or medium doses, but repression of DEGs associated with GO functions such as DNA replication, cell cycle regulation and response to reactive oxygen species (ROS) were observed after 280 mGy gamma exposure. Ortholog-based toxicity pathway analysis further showed that 15 mGy radiation

  18. Dual-energy cone-beam CT with a flat-panel detector: Effect of reconstruction algorithm on material classification

    Energy Technology Data Exchange (ETDEWEB)

    Zbijewski, W., E-mail: wzbijewski@jhu.edu; Gang, G. J.; Xu, J.; Wang, A. S.; Stayman, J. W. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Taguchi, K.; Carrino, J. A. [Russell H. Morgan Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Siewerdsen, J. H. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 and Russell H. Morgan Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States)

    2014-02-15

    Purpose: Cone-beam CT (CBCT) with a flat-panel detector (FPD) is finding application in areas such as breast and musculoskeletal imaging, where dual-energy (DE) capabilities offer potential benefit. The authors investigate the accuracy of material classification in DE CBCT using filtered backprojection (FBP) and penalized likelihood (PL) reconstruction and optimize contrast-enhanced DE CBCT of the joints as a function of dose, material concentration, and detail size. Methods: Phantoms consisting of a 15 cm diameter water cylinder with solid calcium inserts (50–200 mg/ml, 3–28.4 mm diameter) and solid iodine inserts (2–10 mg/ml, 3–28.4 mm diameter), as well as a cadaveric knee with intra-articular injection of iodine were imaged on a CBCT bench with a Varian 4343 FPD. The low energy (LE) beam was 70 kVp (+0.2 mm Cu), and the high energy (HE) beam was 120 kVp (+0.2 mm Cu, +0.5 mm Ag). Total dose (LE+HE) was varied from 3.1 to 15.6 mGy with equal dose allocation. Image-based DE classification involved a nearest distance classifier in the space of LE versus HE attenuation values. Recognizing the differences in noise between LE and HE beams, the LE and HE data were differentially filtered (in FBP) or regularized (in PL). Both a quadratic (PLQ) and a total-variation penalty (PLTV) were investigated for PL. The performance of DE CBCT material discrimination was quantified in terms of voxelwise specificity, sensitivity, and accuracy. Results: Noise in the HE image was primarily responsible for classification errors within the contrast inserts, whereas noise in the LE image mainly influenced classification in the surrounding water. For inserts of diameter 28.4 mm, DE CBCT reconstructions were optimized to maximize the total combined accuracy across the range of calcium and iodine concentrations, yielding values of ∼88% for FBP and PLQ, and ∼95% for PLTV at 3.1 mGy total dose, increasing to ∼95% for FBP and PLQ, and ∼98% for PLTV at 15.6 mGy total dose. For a

  19. Single-energy low-voltage arterial phase MDCT scanning increases conspicuity of adenocarcinoma of the pancreas

    Energy Technology Data Exchange (ETDEWEB)

    Zamboni, Giulia A., E-mail: gzamboni@hotmail.com [Istituto di Radiologia, Policlinico GB Rossi, Azienda Ospedaliera Universitaria Integrata di Verona, P.le LA Scuro 10, 37134 Verona (Italy); Ambrosetti, Maria Chiara, E-mail: mchiara.ambrosetti@gmail.com [Istituto di Radiologia, Policlinico GB Rossi, Azienda Ospedaliera Universitaria Integrata di Verona, P.le LA Scuro 10, 37134 Verona (Italy); Guariglia, Stefania, E-mail: guariglia@gmail.com [U.O. di Fisica Sanitaria, Azienda Ospedaliera Universitaria Integrata di Verona, P.le Stefani 1, 37126 Verona (Italy); Cavedon, Carlo, E-mail: carlo.cavedon@ospedaleuniverona.it [U.O. di Fisica Sanitaria, Azienda Ospedaliera Universitaria Integrata di Verona, P.le Stefani 1, 37126 Verona (Italy); Pozzi Mucelli, Roberto, E-mail: roberto.pozzimucelli@univr.it [Istituto di Radiologia, Policlinico GB Rossi, Azienda Ospedaliera Universitaria Integrata di Verona, P.le LA Scuro 10, 37134 Verona (Italy)

    2014-03-15

    Purpose: To test a single-energy low-voltage CT protocol for pancreatic adenocarcinoma. Methods and materials: A total of 30 patients with pathology-proven pancreatic adenocarcinoma underwent 64-row MDCT with arterial phase at 80 kV and were compared to a similar group of 30 patients scanned with a 120 kV protocol. Scans were compared for quantitative image parameters (attenuation and standard deviation in the pancreas, tumor, aorta), CTDI and DLP using an unpaired t-test. Image noise values for each protocol (SD of the psoas) were compared using an unpaired t-test. Effective dose was calculated for each protocol. CNR (=conspicuity/SDnoise) and FOM (CNR{sup 2}/ED) were calculated. The Catphan600 phantom was used to evaluate image non-uniformity, noise, spatial resolution, and low contrast detectability. Results: Mean patient weight was 68 kg in the study group and 73 kg in the control group (p = 0.0355), while patient diameters at the celiac axis were not significantly different. Mean attenuation was significantly higher at 80 kV in the aorta (517.5 ± 116.4 vs 290.3 ± 76.4 HU) and normal pancreas (154.0 ± 39.95 vs 90.02 ± 19.01 HU) (all p < 0.0001), while no significant difference was observed for adenocarcinoma (61.43 ± 35.61 vs 47.45 ± 18.95; p = n.s.). CTDI and DLP were significantly lower at 80 kV (6.00 ± 0.90 mGy vs 10.24 ± 2.93 mGy, and 180.4 ± 35.49 mGy cm vs 383.8 ± 117 mGy cm, respectively; all p < 0.0001). Tumor conspicuity (HU{sub pancreas} − HU{sub tumor}) was significantly higher at 80 kV (94.2 ± 39.3 vs 39.5 ± 22 HU; p < 0.0001). Mean image noise was significantly higher at 80 kV (28.32 ± 10.06 vs 19.7 ± 7.1 HU; p < 0.0001). Effective dose was significantly lower at 80 kV (1.984 ± 0.39 vs 5.75 ± 1.75 mSv; p < 0.0001). The total DLP for the exam was 1024 ± 31.86 mGy cm for the 80 kV protocol and 1357 ± 62.60 mGy cm for the 120 kV protocol (p < 0.0001). Phantoms showed higher non-uniformity, slightly higher noise, slightly lower MTF

  20. Melt segregation in the Muroto Gabbroic Intrusion, Cape Muroto - Japan

    Science.gov (United States)

    Floess, David; Caricchi, Luca; Wallis, Simon

    2014-05-01

    Melt segregation is a crucial process in igneous petrology and is commonly used to explain characteristic geochemical trends of magmatic rocks (e.g. Brophy 1991), as well as the accumulation of large amounts of eruptible magma (e.g. Bachmann & Bergantz, 2008). In order to gain further insight into the physical processes behind melt segregation we investigated a small-scale, natural setting. The Miocene Muroto Gabbroic Intrusion (MGI) is a 230m thick, layered sill located at Cape Muroto (Shikoku Island - Japan; Yoshizawa, 1953). It was rotated into a near-vertical (~70°) orientation after horizontal emplacement, allowing for easy sampling of the entire sill from bottom to top. We collected ~70 oriented samples for petrographic and geochemical analysis, as well as for structural analysis using Anisotropy of Magnetic Susceptibility (AMS). A well-defined horizon (zone I) between 50 and 125m from the bottom shows spectacular evidence for the segregation of felsic melts from the mafic mush (Hoshide et al. 2006). Individual, cm- to m-sized, anorthositic melt lenses mainly consist of plagioclase laths with minor cpx. Small diapirs emanate from the melt lenses and clearly indicate the paleo-upward direction of the sill. Zone I is overlaid by a coarse-grained gabbro (zone II) with cm-sized crystals of plag+cpx and no anorthositic segregations can be found. The MGI grades into fine-grained dolerite towards the top and bottom margins of the sill. We modeled the phase relations of a representative MGI gabbro composition (chilled margin) upon cooling using MELTS (Gualda et al. 2012). Extracted physical parameters (i.e. melt and solid densities, melt viscosity) were used as a proxy for melt mobility (Sakamaki et al. 2013). The temporal and spatial evolution of melt mobility within the sill was investigated using the temperature-time curve obtained through a thermal model for the MGI. We observed several peaks for the melt mobility, implying zones of melt drainage (when mobility

  1. Dosimetric characterization and organ dose assessment in digital breast tomosynthesis: Measurements and Monte Carlo simulations using voxel phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Baptista, Mariana, E-mail: marianabaptista@ctn.ist.utl.pt; Di Maria, Salvatore; Barros, Sílvia; Vaz, Pedro [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, km 139,7, Bobadela LRS 2695-066 (Portugal); Figueira, Catarina [Centre for Plasma Physics, School of Mathematics and Physics, Queen’s University, Belfast BT7 1NN (United Kingdom); Sarmento, Marta; Orvalho, Lurdes [Serviço de Imagiologia, Hospital da Luz, Avenida Lusíada, 100, Lisboa 1500-650 (Portugal)

    2015-07-15

    Purpose: Due to its capability to more accurately detect deep lesions inside the breast by removing the effect of overlying anatomy, digital breast tomosynthesis (DBT) has the potential to replace the standard mammography technique in clinical screening exams. However, the European Guidelines for DBT dosimetry are still a work in progress and there are little data available on organ doses other than to the breast. It is, therefore, of great importance to assess the dosimetric performance of DBT with respect to the one obtained with standard digital mammography (DM) systems. The aim of this work is twofold: (i) to study the dosimetric properties of a combined DBT/DM system (MAMMOMAT Inspiration Siemens{sup ®}) for a tungsten/rhodium (W/Rh) anode/filter combination and (ii) to evaluate organs doses during a DBT examination. Methods: For the first task, measurements were performed in manual and automatic exposure control (AEC) modes, using two homogeneous breast phantoms: a PMMA slab phantom and a 4 cm thick breast-shaped rigid phantom, with 50% of glandular tissue in its composition. Monte Carlo (MC) simulations were performed using Monte Carlo N-Particle eXtended v.2.7.0. A MC model was implemented to mimic DM and DBT acquisitions for a wide range of x-ray spectra (24 –34 kV). This was used to calculate mean glandular dose (MGD) and to compute series of backscatter factors (BSFs) that could be inserted into the DBT dosimetric formalism proposed by Dance et al. Regarding the second aim of the study, the implemented MC model of the clinical equipment, together with a female voxel phantom (“Laura”), was used to calculate organ doses considering a typical DBT acquisition. Results were compared with a standard two-view mammography craniocaudal (CC) acquisition. Results: Considering the AEC mode, the acquisition of a single CC view results in a MGD ranging from 0.53 ± 0.07 mGy to 2.41 ± 0.31 mGy in DM mode and from 0.77 ± 0.11 mGy to 2.28 ± 0.32 mGy in DBT mode

  2. Radiation dose from multidetector CT studies in children: results from the first Italian nationwide survey

    Energy Technology Data Exchange (ETDEWEB)

    Granata, Claudio [IRCCS Istituto Giannina Gaslini, Department of Radiology, Genoa (Italy); Origgi, Daniela; Palorini, Federica [Istituto Europeo di Oncologia, Department of Medical Physics, Milan (Italy); Matranga, Domenica [University of Palermo, Department of Sciences for Health Promotion and Mother and Child Care ' ' G. D' Alessandro' ' , Palermo (Italy); Salerno, Sergio [University of Palermo, Department of Medical and Forensic Biopathology and Biotechnologies, Section of Radiology, Palermo (Italy)

    2015-05-01

    Multidetector CT (MDCT) scanners have contributed to the widespread use of CT in paediatric imaging. However, concerns are raised for the associated radiation exposure. Very few surveys on radiation exposure from MDCT studies in children are available. The aim of this study was to outline the status of radiation exposure in children from MDCT practice in Italy. In this retrospective multicentre study we asked Italian radiology units with an MDCT scanner with at least 16 slices to provide dosimetric and acquisition parameters of CT examinations in three age groups (1-5, 6-10, 11-15 years) for studies of head, chest and abdomen. The dosimetric results were reported in terms of third-quartile volumetric CT dose index (CTDI{sub vol}) (mGy), size-specific dose estimate (SSDE) (mGy), dose length product (DLP) (mGy cm), and total DLP for multiphase studies. These results were compared with paediatric European and adult Italian published data. A multivariate analysis assessed the association of CTDI{sub vol} with patient characteristics and scanning modalities. We collected data from 993 MDCT examinations performed at 25 centres. For age groups 1-5 years, 6-10 years and 11-15 years, the CTDI{sub vol}, DLP and total DLP values were statistically significantly below the values observed in our analogous national survey in adults, although the difference decreased with increasing age. CTDI{sub vol} variability among centres was statistically significant (variance = 0.07; 95% confidence interval = 0.03-0.16; P < 0.001). This study reviewed practice in Italian centres performing paediatric imaging with MDCT scanners. The variability of doses among centres suggests that the use of standardised CT protocols should be encouraged. (orig.)

  3. CT image quality in sinogram affirmed iterative reconstruction phantom study - is there a point of diminishing returns?

    Energy Technology Data Exchange (ETDEWEB)

    Infante, Juan C. [University of Miami, Department of Radiology, Miami, FL (United States); Ann and Robert H. Lurie Children' s Hospital of Chicago, Department of Medical Imaging, Chicago, IL (United States); Liu, Yu [Medical College of Wisconsin, Department of Radiology, Milwaukee, WI (United States); Rigsby, Cynthia K. [Ann and Robert H. Lurie Children' s Hospital of Chicago, Department of Medical Imaging, Chicago, IL (United States); Northwestern University Feinberg School of Medicine, Department of Radiology, Chicago, IL (United States); Northwestern University Feinberg School of Medicine, Department of Pediatrics, Chicago, IL (United States)

    2017-03-15

    In our pediatric practice, we have observed qualitatively limited improvement in the image quality of images generated with sinogram affirmed iterative reconstruction (SAFIRE) compared to series generated with filtered back projection (FBP), particularly in cases near or below a CT dose index volume (CTDI{sub vol}) of 1-mGy. To determine whether the image quality advantage of SAFIRE remains constant across clinically used CT dose levels in an American College of Radiology (ACR) CT accreditation phantom including the lower dose range used in pediatric imaging. An exemption from institutional review board approval was obtained for this phantom-based study. An ACR quality phantom was scanned in incremental kV steps and effective tube current intervals. Acquisitions were reconstructed with FBP and SAFIRE strengths of 1, 3 and 5. Image quality measures were calculated including signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), low-contrast resolution and high-contrast resolution. Peak SNR was also calculated. Descriptive and nonparametric statistics were used to compare these image quality metrics while normalizing to CT dose index (CTDI). The percent improvement in SNR and peak SNR of SAFIRE reconstructions compared to FBP decreased from about 70% for image sets acquired above a 1.42 mGy CTDI to 25% at a 0.25 mGy CTDI. CNR improvement with SAFIRE did not vary with dose. No significant difference was seen in the low-contrast resolution or high-contrast resolution of SAFIRE images compared to FBP. SNR did not improve equally after applying SAFIRE across a spectrum clinically used CTDIs. Below a threshold CTDI, the incremental improvement of SAFIRE compared to FBP decreased. (orig.)

  4. Clinical micro-CT for dental imaging

    Science.gov (United States)

    Youn, Hanbean; Cho, Min Kook; Shon, Cheol-Soon; Cho, Bong Hae; Kim, Chang Hyuk; Kim, Ho Kyung

    2009-02-01

    We exploit the development of a clinical computed microtomography (micro-CT) system for dental imaging. While the conventional dental CT simply serves implant treatment, the clinical dental micro-CT may provide clinicians with a histologic evaluation. To investigate the feasibility of the realization of a dental micro-CT, we have constructed an experimental test system which mainly consists of a microfocus x-ray source, a rotational subject holder, and a flat-panel detector. The flat-panel detector is based on a matrix-addressed photodiode array coupled to a CsI:Tl scintillator. The detective quantum efficiency (DQE) of the detector was measured as a function of magnification based on the measured modulation-transfer function (MTF) and noise-power spectrum (NPS). The best MTF and DQE performances were achieved at the magnification factor of 3. Similar tendency of the spatial resolving power in tomography was also observed with a wire phantom having a 25 μm diameter. From the investigation of tomographs reconstructed from a humanoid skull phantom, the application of magnification in the system largely reduced both signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for a fixed dose at the entrance surface of the detector, 1.2 mGy, while this setup increased the dose at the object plane from 4.7 mGy to 19.1 mGy for the magnification factor from 2 to 4, respectively. Although the quantum mottles at the high magnification factor tackled the practical use in the clinic, the information contained in the magnified CT images was quite promising.

  5. Thermoluminescent dosimetry in computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lara C, A.; Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Legaria, Av. Legaria 694, Col. Irrigacion, 11500 Ciudad de Mexico (Mexico); Osorio V, M. [ISSSTE, Centro Medico Nacional 20 de Noviembre, Felix Cuevas 540, Col. del Valle, 03100 Ciudad de Mexico (Mexico); Hernandez O, O., E-mail: armando_lara_cam@yahoo.com.mx [Hospital General de Mexico, Dr. Balmis 148, Col. Doctores, 06726 Ciudad de Mexico (Mexico)

    2016-10-15

    In this work we studied the dosimetry performed on CT scan in two different equipment, SOMATOM and Phillips, with 16 and 64 slice respectively. We used 51 pellets of lithium fluoride doped with magnesium and titanium (LiF: Mg, Ti) also knows as TLD-100 due to its physical properties and its easy of use, in this study, first analysis a batch of 56 pellets, but only 53 pellets were optimal for this study, cesium-137 was used as source irradiation, then proceeded to calibrate the batch with X-rays source, measuring the corresponding dose in a Farmers ionization chamber, then, we obtained a calibration curve, and we used as reference to calculation of the applied dose, finally designing ergonomic mesh, were it was deposited a TLD 100, placed in a regions of interest were made to each scan type. Once characterized our material proceeded to testing in 30 patients, which were irradiated with X-ray tube, whose operation was performed at 80, 120 kV with a current of 100, 300 and 400 m A according to scanning protocol. Overall we measured dose of 5 mGy to 53 mGy, these measurements reflect significant dose to can induced cancer, due previous reports published, that doses greater than 20 mGy there is a risk of developing cancer in the long term, but in practice when it assigned a medical diagnosis, there are no dose limits due to benefits patients, however, IAEA publish recommendations that allow us to carry out optimum handling of ionizing radiation, among these is the quality control of the tomography equipment that helps greatly reduce patient dose. (Author)

  6. Properties of BGO thin films under the influence of gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Arshak, K. [Electronic and Computer Engineering Department, University of Limerick, Limerick (Ireland)], E-mail: khalil.arshak@ul.ie; Korostynska, O.; Harris, J. [Electronic and Computer Engineering Department, University of Limerick, Limerick (Ireland); Morris, D.; Arshak, A. [Physics Department, University of Limerick, Limerick (Ireland); Jafer, E. [Electronic and Computer Engineering Department, University of Limerick, Limerick (Ireland)

    2008-02-15

    It is important to know the behaviour of materials under the influence of radiation for the effective design of novel sensor systems. Optical properties of bismuth germinate (Bi{sub 4}Ge{sub 3}O{sub 12}-BGO) thin films were investigated in terms of their perception to gamma radiation exposure. An Edwards E306A vacuum thermal coating system was used for thin films deposition. BGO films with a thickness of 200 nm were exposed to a disk-type {sup 137}Cs gamma radiation source with an activity of 370 kBq. Optical properties of the films were investigated using CARY IE UV-Visible Spectrophotometer. Calculated optical band gap for as-deposited BGO thin film was 1.95 eV. Gamma radiation induced changes in the optical properties of thin films, which could be explained by the variation in the degree of disorder. From the density-of-state model, it is known that optical band gap decreases with an increasing degree of disorder of the amorphous phase. Electrical properties of BGO thin films were recorded in real time using a low power capacitive interface system with a high resolution, which is based on Delta-sigma modulator. At doses from 0 to 1.5 mGy little if any changes in the capacitance were measured. This could be explained by co-existence of two processes, namely creation and annihilation of defects under the influence of radiation. After a threshold dose of 1.5 mGy creation of defects becomes more prevailing and the BGO film capacitance has gradually increased in value from 2.97 pF to 7.09 pF after irradiation with a 2.44 mGy dose.

  7. Measurement of eye lens dose for Varian On-Board Imaging with different cone-beam computed tomography acquisition techniques

    Directory of Open Access Journals (Sweden)

    Sudesh Deshpande

    2016-01-01

    Full Text Available The objective of this work was to measure patient eye lens dose for different cone-beam computed tomography (CBCT acquisition protocols of Varian′s On-Board Imaging (OBI system using optically stimulated luminescence dosimeter (OSLD and to study the variation in eye lens dose with patient geometry and distance of isocenter to the eye lens. During the experimental measurements, OSLD was placed on the patient between the eyebrows of both eyes in line of nose during CBCT image acquisition to measure eye lens doses. The eye lens dose measurements were carried out for three different cone-beam acquisition protocols (standard dose head, low-dose head [LDH], and high-quality head [HQH] of Varian OBI. Measured doses were correlated with patient geometry and distance between isocenter and eye lens. Measured eye lens doses for standard head and HQH protocols were in the range of 1.8-3.2 mGy and 4.5-9.9 mGy, respectively. However, the measured eye lens dose for the LDH protocol was in the range of 0.3-0.7 mGy. The measured data indicate that eye lens dose to patient depends on the selected imaging protocol. It was also observed that eye lens dose does not depend on patient geometry but strongly depends on distance between eye lens and treatment field isocenter. However, undoubted advantages of imaging system should not be counterbalanced by inappropriate selection of imaging protocol, especially for very intense imaging protocol.

  8. SU-F-I-32: Organ Doses from Pediatric Head CT Scan

    Energy Technology Data Exchange (ETDEWEB)

    Liu, H; Liu, Q; Qiu, J; Zhuo, W [Institute of Radiation Medicine Fudan University, Shanghai (China); Majer, M; Knezevic, Z; Miljanic, S [Radiation Chemistry and Dosimetry Laboratory, Ruder Boskovic Institute, Zagreb (Croatia); Hrsak, H [Clinical Hospital Centre Zagreb, Zagreb (Croatia)

    2016-06-15

    Purpose: To evaluate the organ doses of pediatric patients who undergoing head CT scan using Monte Carlo (MC) simulation and compare it with measurements in anthropomorphic child phantom.. Methods: A ten years old children voxel phantom was developed from CT images, the voxel size of the phantom was 2mm*2mm*2mm. Organ doses from head CT scan were simulated using MCNPX software, 180 detectors were placed in the voxel phantom to tally the doses of the represented tissues or organs. When performing the simulation, 120 kVp and 88 mA were selected as the scan parameters. The scan range covered from the top of the head to the end of the chain, this protocol was used at CT simulator for radiotherapy. To validate the simulated results, organ doses were measured with radiophotoluminescence (RPL) detectors, placed in the 28 organs of the 10 years old CIRS ATOM phantom. Results: The organ doses results matched well between MC simulation and phantom measurements. The eyes dose was showed to be as expected the highest organ dose: 28.11 mGy by simulation and 27.34 mGy by measurement respectively. Doses for organs not included in the scan volume were much lower than those included in the scan volume, thymus doses were observed more than 10 mGy due the CT protocol for radiotherapy covered more body part than routine head CT scan. Conclusion: As the eyes are superficial organs, they may receive the highest radiation dose during the CT scan. Considering the relatively high radio sensitivity, using shielding material or organ based tube current modulation technique should be encouraged to reduce the eye radiation risks. Scan range was one of the most important factors that affects the organ doses during the CT scan. Use as short as reasonably possible scan range should be helpful to reduce the patient radiation dose. This work was supported by the National Natural Science Foundation of China(11475047)

  9. Risk of hematological malignancies among Chernobyl liquidators

    Science.gov (United States)

    Kesminiene, Ausrele; Evrard, Anne-Sophie; Ivanov, Viktor K.; Malakhova, Irina V.; Kurtinaitis, Juozas; Stengrevics, Aivars; Tekkel, Mare; Anspaugh, Lynn R.; Bouville, André; Chekin, Sergei; Chumak, Vadim V.; Drozdovitch, Vladimir; Gapanovich, Vladimir; Golovanov, Ivan; Hubert, Phillip; Illichev, Sergei V.; Khait, Svetlana E.; Krjuchkov, Viktor P.; Maceika, Evaldas; Maksyoutov, Marat; Mirkhaidarov, Anatoly K.; Polyakov, Semion; Shchukina, Natalia; Tenet, Vanessa; Tserakhovich, Tatyana I.; Tsykalo, Aleksandr; Tukov, Aleksandr R.; Cardis, Elisabeth

    2010-01-01

    A case-control study of hematological malignancies was conducted among Chernobyl liquidators (accident recovery workers) from Belarus, Russia and Baltic countries in order to assess the effect of low-to-medium dose protracted radiation exposures on the relative risk of these diseases. The study was nested within cohorts of liquidators who had worked in 1986–87 around the Chernobyl plant. 117 cases (69 leukemia, 34 non-Hodgkin Lymphoma (NHL) and 14 other malignancies of lymphoid and hematopoietic tissue) and 481 matched controls were included in the study. Individual dose to the bone marrow and uncertainties were estimated for each subject. The main analyses were restricted to 70 cases (40 leukemia, 20 NHL and 10 other) and their 287 matched controls with reliable information on work in the Chernobyl area. Most subjects received very low doses (median 13 mGy). For all diagnoses combined, a significantly elevated OR was seen at doses of 200 mGy and above. The Excess Relative Risk (ERR) per 100 mGy was 0.60 (90% confidence interval (CI): −0.02, 2.35). The corresponding estimate for leukemia excluding chronic lymphoid leukemia (CLL) was 0.50 (90%CI −0.38, 5.7). It is slightly higher than, but statistically compatible with, those estimated from a-bomb survivors and recent low dose-rate studies. Although sensitivity analyses showed generally similar results, we cannot rule out the possibility that biases and uncertainties could have led to over or underestimation of the risk in this study. PMID:19138033

  10. Single-phase DECT with VNCT compared with three-phase CTU in patients with haematuria

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung Jae; Park, Byung Kwan; Kim, Chan Kyo [Sungkyunkwan University School of Medicine, Department of Radiology, Samsung Medical Center, Seoul (Korea, Republic of)

    2016-10-15

    To retrospectively evaluate the diagnostic performance of single-phase dual-energy CT (DECT) with virtual non-contrast CT (VNCT) compared with three-phase CT urography (CTU) in patients with haematuria. A total of 296 patients underwent three-phase CTU (NCT at 120 kVp; nephrographic phase and excretory phase DECTs at 140 kVp and 80 kVp) owing to haematuria. Diagnostic performances of CT scans were compared for detecting urothelial tumours and urinary stones. Dose-length product (DLP) was compared in relation to single-phase DECT and three-phase CTU Dose-length product (DLP) was compared in relation to single-phase DECT and three-phase CTU. Sensitivity and specificity for tumour were 95 % (19/20) and 98.9 % (273/276) on CTU, 95 % (19/20) and 98.2 % (271/276) on nephrographic phase DECT, and 90 % (18/20) and 98.2 % (271/276) on excretory phase DECT (P > 0.1). Of the 148 stones detected on NCT, 108 (73 %) and 100 (67.6 %) were detected on nephrographic phase and excretory phase VNCTs, respectively. The mean size of stones undetected on nephrographic and excretory VNCTs was measured as 1.5 ± 0.5 mm and 1.6 ± 0.6 mm, respectively. The mean DLPs of three-phase CTU, nephrographic phase DECT and excretory phase DECT were 1076 ± 248 mGy . cm, 410 ± 98 mGy . cm, and 360 ± 87 mGy . cm, respectively (P < 0.001). Single-phase DECT has a potential to replace three-phase CTU for detecting tumours with a lower radiation dose. (orig.)

  11. Estimation of thyroid radiation doses for the hanford thyroid disease study: results and implications for statistical power of the epidemiological analyses.

    Science.gov (United States)

    Kopecky, Kenneth J; Davis, Scott; Hamilton, Thomas E; Saporito, Mark S; Onstad, Lynn E

    2004-07-01

    Residents of eastern Washington, northeastern Oregon, and western Idaho were exposed to I released into the atmosphere from operations at the Hanford Nuclear Site from 1944 through 1972, especially in the late 1940's and early 1950's. This paper describes the estimated doses to the thyroid glands of the 3,440 evaluable participants in the Hanford Thyroid Disease Study, which investigated whether thyroid morbidity was increased in people exposed to radioactive iodine from Hanford during 1944-1957. The participants were born during 1940-1946 to mothers living in Benton, Franklin, Walla Walla, Adams, Okanogan, Ferry, or Stevens Counties in Washington State. Whenever possible someone with direct knowledge of the participant's early life (preferably the participant's mother) was interviewed about the participant's individual dose-determining characteristics (residence history, sources and quantities of food, milk, and milk products consumed, production and processing techniques for home-grown food and milk products). Default information was used if no interview respondent was available. Thyroid doses were estimated using the computer program Calculation of Individual Doses from Environmental Radionuclides (CIDER) developed by the Hanford Environmental Dose Reconstruction Project. CIDER provided 100 sets of doses to represent uncertainty of the estimates. These sets were not generated independently for each participant, but reflected the effects of uncertainties in characteristics shared by participants. Estimated doses (medians of each participant's 100 realizations) ranged from 0.0029 mGy to 2823 mGy, with mean and median of 174 and 97 mGy, respectively. The distribution of estimated doses provided the Hanford Thyroid Disease Study with sufficient statistical power to test for dose-response relationships between thyroid outcomes and exposure to Hanford's I.

  12. A Manganese Superoxide Dismutase (SOD2)-Mediated Adaptive Response

    Science.gov (United States)

    Grdina, David J.; Murley, Jeffrey S.; Miller, Richard C.; Mauceri, Helena J.; Sutton, Harold G.; Thirman, Michael J.; Li, Jian Jian; Woloschak, Gayle E.; Weichselbaum, Ralph R.

    2013-01-01

    Very low doses of ionizing radiation, 5 to 100 mGy, can induce adaptive responses characterized by elevation in cell survival and reduction in micronuclei formation. Utilizing these end points, RKO human colon carcinoma and transformed mouse embryo fibroblasts (MEF), wild-type or knockout cells missing TNF receptors 1 and 2 (TNFR1−R2−), and C57BL/6 and TNFR1−R2− knockout mice, we demonstrate that intact TNF signaling is required for induction of elevated manganese superoxide dismutase (SOD2) activity (P adaptive responses when cells are challenged at a later time with 2 Gy. In contrast, amifostine’s free thiol form WR1065 can directly activate NF-κB giving rise to elevated SOD2 activity 24 h later and induce an adaptive response in both MEF wild-type and TNF signaling defective TNFR1−R2− cells. Transfection of cells with SOD2 siRNA completely abolishes both the elevation in SOD2 activity and expression of the adaptive responses. These results were confirmed in vivo using a micronucleus assay in splenocytes derived from C57BL/6 and TNFR1−R2− knockout mice that were exposed to 100 mGy or 400 mg/kg amifostine 24 h prior to exposure to a 2 Gy whole-body dose. A dose of 100 mGy also conferred enhanced protection to C57BL/6 mice exposed 24 h later to 100 mg/kg of N-Ethyl-N-nitrosourea (ENU). While very low radiation doses require an intact TNF signaling process to induce a SOD2-mediated adaptive response, amifostine can induce a similar adaptive response in both TNF receptor competent and knockout cells, respectively. PMID:23237540

  13. A Survivin-Associated Adaptive Response in Radiation Therapy

    Science.gov (United States)

    Grdina, David J.; Murley, Jeffrey S.; Miller, Richard C.; Mauceri, Helena J.; Sutton, Harold G.; Li, Jian Jian; Woloschak, Gayle E.; Weichselbaum, Ralph R.

    2013-01-01

    Adaptive responses can be induced in cells by very low doses of ionizing radiation resulting in an enhanced resistance to much larger exposures. The inhibitor of apoptosis (IAP) protein, survivin, has been implicated in many adaptive responses to cellular stress. Computerized axial tomography (CAT) used in image guided radiotherapy to position and monitor tumor response utilizes very low radiation doses ranging from 0.5 to 100 mGy. We investigated the ability of these very low radiation doses administered along with two 2 Gy doses separated by 24 h, a standard conventional radiotherapy dosing schedule, to initiate adaptive responses resulting in the elevation of radiation resistance in exposed cells. Human colon carcinoma (RKO36), mouse sarcoma (SA-NH), along with transformed mouse embryo fibroblasts (MEF), wild type (WT) or cells lacking functional tumor necrosis factor receptors 1 and 2 (TNFR1−R2−) were used to assess their relative ability to express an adaptive response when grown either to confluence in vitro or as tumors in the flank of C57BL/6 mice. The survival of each of these cells was elevated from 5 to 20% (P ≤ 0.05) as compared to cells not receiving a 100 mGy or lesser dose. Additionally, the cells exposed to 100 mGy exhibited elevations in survivin levels, reductions in apoptosis frequencies, and loss of an adaptive response if transfected with survivin siRNA. This survivin-mediated adaptive response has the potential for affecting outcomes if regularly induced throughout a course of image guided radiation therapy. PMID:23651635

  14. Estimation of computed tomography dose in various phantom shapes and compositions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Lae [Dept. of Radiological Science, Yonsei University, Seoul (Korea, Republic of)

    2017-03-15

    The purpose of this study was to investigate CTDI (computed tomography dose index at center) for various phantom shapes, sizes, and compositions by using GATE (geant4 application for tomographic emission) simulations. GATE simulations were performed for various phantom shapes (cylinder, elliptical, and hexagonal prism PMMA phantoms) and phantom compositions (water, PMMA, polyethylene, polyoxymethylene) with various diameters (1-50 cm) at various kVp and mAs levels. The CTDI100center values of cylinder, elliptical, and hexagonal prism phantom at 120 kVp, 200 mAs resulted in 11.1, 13.4, and 12.2 mGy, respectively. The volume is the same, but CTDI{sub 100center} values are different depending on the type of phantom. The water, PMMA, and polyoxymethylene phantom CTDI{sub 100center} values were relatively low as the material density increased. However, in the case of Polyethylene, the CTDI{sub 100center} value was higher than that of PMMA at diameters exceeding 15 cm (CTDI{sub 100center} : 35.0 mGy). And a diameter greater than 30 cm (CTDI{sub 100center} : 17.7 mGy) showed more CTDI{sub 100center} than Water. We have used limited phantoms to evaluate CT doses. In this study, CTDI{sub 100center} values were estimated and simulated by GATE simulation according to the material and shape of the phantom. CT dosimetry can be estimated more accurately by using various materials and phantom shapes close to human body.

  15. Dose and diagnostic image quality in digital tomosynthesis imaging of facial bones in pediatrics

    Science.gov (United States)

    King, J. M.; Hickling, S.; Elbakri, I. A.; Reed, M.; Wrogemann, J.

    2011-03-01

    The purpose of this study was to evaluate the use of digital tomosynthesis (DT) for pediatric facial bone imaging. We compared the eye lens dose and diagnostic image quality of DT facial bone exams relative to digital radiography (DR) and computed tomography (CT), and investigated whether we could modify our current DT imaging protocol to reduce patient dose while maintaining sufficient diagnostic image quality. We measured the dose to the eye lens for all three modalities using high-sensitivity thermoluminescent dosimeters (TLDs) and an anthropomorphic skull phantom. To assess the diagnostic image quality of DT compared to the corresponding DR and CT images, we performed an observer study where the visibility of anatomical structures in the DT phantom images were rated on a four-point scale. We then acquired DT images at lower doses and had radiologists indicate whether the visibility of each structure was adequate for diagnostic purposes. For typical facial bone exams, we measured eye lens doses of 0.1-0.4 mGy for DR, 0.3-3.7 mGy for DT, and 26 mGy for CT. In general, facial bone structures were visualized better with DT then DR, and the majority of structures were visualized well enough to avoid the need for CT. DT imaging provides high quality diagnostic images of the facial bones while delivering significantly lower doses to the lens of the eye compared to CT. In addition, we found that by adjusting the imaging parameters, the DT effective dose can be reduced by up to 50% while maintaining sufficient image quality.

  16. Performances of low-dose dual-energy CT in reducing artifacts from implanted metallic orthopedic devices

    Energy Technology Data Exchange (ETDEWEB)

    Filograna, Laura [Catholic University of Rome, School of Medicine, University Hospital ' ' A. Gemelli' ' , Department of Radiological Sciences, Institute of Radiology, Rome (Italy); University of Zurich, Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, Zurich (Switzerland); Magarelli, Nicola; Leone, Antonio; Bonomo, Lorenzo [Catholic University of Rome, School of Medicine, University Hospital ' ' A. Gemelli' ' , Department of Radiological Sciences, Institute of Radiology, Rome (Italy); De Waure, Chiara; Calabro, Giovanna Elisa [Catholic University of Rome, School of Medicine, University Hospital ' ' A. Gemelli' ' , Research Centre for Health Technology Assessment, Department of Public Health, Section of Hygiene, Rome (Italy); Finkenstaedt, Tim [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Thali, Michael John [University of Zurich, Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, Zurich (Switzerland)

    2016-07-15

    The objective was to evaluate the performances of dose-reduced dual-energy computed tomography (DECT) in decreasing metallic artifacts from orthopedic devices compared with dose-neutral DECT, dose-neutral single-energy computed tomography (SECT), and dose-reduced SECT. Thirty implants in 20 consecutive cadavers underwent both SECT and DECT at three fixed CT dose indexes (CTDI): 20.0, 10.0, and 5.0 mGy. Extrapolated monoenergetic DECT images at 64, 69, 88, 105, 120, and 130 keV, and individually adjusted monoenergy for optimized image quality (OPTkeV) were generated. In each group, the image quality of the seven monoenergetic images and of the SECT image was assessed qualitatively and quantitatively by visually rating and by measuring the maximum streak artifact respectively. The comparison between SECT and OPTkeV evaluated overall within all groups showed a significant difference (p <0.001), with OPTkeV images providing better images. Comparing OPTkeV with the other DECT images, a significant difference was shown (p <0.001), with OPTkeV and 130-keV images providing the qualitatively best results. The OPTkeV images of 5.0-mGy acquisitions provided percentages of images with scores 1 and 2 of 36 % and 30 % respectively, compared with 0 % and 33.3 % of the corresponding SECT images of 10- and 20-mGy acquisitions. Moreover, DECT reconstructions at the OPTkeV of the low-dose group showed higher CT numbers than the SECT images of dose groups 1 and 2. This study demonstrates that low-dose DECT permits a reduction of artifacts due to metallic implants to be obtained in a similar manner to neutral-dose DECT and better than reduced or neutral-dose SECT. (orig.)

  17. Performance of cone-beam computed tomography and multidetector computed tomography in diagnostic imaging of the midface: A comparative study on Phantom and cadaver head scans

    Energy Technology Data Exchange (ETDEWEB)

    Veldhoen, Simon [University Medical Center Hamburg, Department of Diagnostic and Interventional Radiology, Hamburg (Germany); University Hospital Wuerzburg, Department of Diagnostic and Interventional Radiology, Wuerzburg (Germany); Schoellchen, Maximilian; Hanken, H.; Precht, C.; Heiland, M. [University Medical Center Hamburg, Department of Oral- and Maxillofacial Surgery, Hamburg (Germany); Henes, F.O.; Adam, G.; Regier, M. [University Medical Center Hamburg, Department of Diagnostic and Interventional Radiology, Hamburg (Germany); Schoen, G. [University Medical Center Hamburg, Department of Medical Biometry and Epidemiology, Hamburg (Germany); Nagel, H.D. [Science and Technology for Radiology, Buchholz (Germany); Schumacher, U. [University Medical Center Hamburg, Institute of Anatomy, Hamburg (Germany)

    2017-02-15

    To compare multidetector computed tomography (MDCT) and cone-beam computed tomography (CBCT) regarding radiation, resolution, image noise, and image quality. CBCT and 256-MDCT were compared based on three scan protocols: Standard-dose (∼24 mGy), reduced-dose (∼9 mGy), and low-dose (∼4 mGy). MDCT images were acquired in standard- and high-resolution mode (HR-MDCT) and reconstructed using filtered back projection (FBP) and iterative reconstruction (IR). Spatial resolution in linepairs (lp) and objective image noise (OIN) were assessed using dedicated phantoms. Image quality was assessed in scans of 25 cadaver heads using a Likert scale. OIN was markedly higher in FBP-MDCT when compared to CBCT. IR lowered the OIN to comparable values in standard-mode MDCT only. CBCT provided a resolution of 13 lp/cm at standard-dose and 11 lp/cm at reduced-dose vs. 11 lp/cm and 10 lp/cm in HR-MDCT. Resolution of 10 lp/cm was observed for both devices using low-dose settings. Quality scores of MDCT and CBCT did not differ at standard-dose (CBCT, 3.4; MDCT, 3.3-3.5; p > 0.05). Using reduced- and low-dose protocols, CBCT was superior (reduced-dose, 3.2 vs. 2.8; low dose, 3.0 vs. 2.3; p < 0.001). Using the low-dose protocol, the assessed CBCT provided better objective and subjective image quality and equality in resolution. Similar image quality, but better resolution using CBCT was observed at higher exposure settings. (orig.)

  18. SU-E-I-34: Evaluating Use of AEC to Lower Dose for Lung Cancer Screening CT Protocols

    Energy Technology Data Exchange (ETDEWEB)

    Arbique, G; Anderson, J [UT Southwestern Medical Ctr at Dallas, Dallas, TX (United States); Guild, J; Duan, X [UT Southwestern Medical Center, Dallas, TX (United States); Malguria, N; Omar, H; Brewington, C [Ut Southwestern, Dallas, TX (United States); Zhang, D [Toshiba America Medical Systems, Tustin, CA (United States)

    2015-06-15

    Purpose: The National Lung Screening Trial mandated manual low dose CT technique factors, where up to a doubling of radiation output could be used over a regular to large patient size range. Recent guidance from the AAPM and ACR for lung cancer CT screening recommends radiation output adjustment for patient size either through AEC or a manual technique chart. This study evaluated the use of AEC for output control and dose reduction. Methods: The study was performed on a multidetector helical CT scanner (Aquillion ONE, Toshiba Medical) equipped with iterative reconstruction (ADIR-3D), AEC was adjusted with a standard deviation (SD) image quality noise index. The protocol SD parameter was incrementally increased to reduce patient population dose while image quality was evaluated by radiologist readers scoring the clinical utility of images on a Likert scale. Results: Plots of effective dose vs. body size (water cylinder diameter reported by the scanner) demonstrate monotonic increase in patient dose with increasing patient size. At the initial SD setting of 19 the average CTDIvol for a standard size patient was ∼ 2.0 mGy (1.2 mSv effective dose). This was reduced to ∼1.0 mGy (0.5 mSv) at an SD of 25 with no noticeable reduction in clinical utility of images as demonstrated by Likert scoring. Plots of effective patient diameter and BMI vs body size indicate that these metrics could also be used for manual technique charts. Conclusion: AEC offered consistent and reliable control of radiation output in this study. Dose for a standard size patient was reduced to one-third of the 3 mGy CTDIvol limit required for ACR accreditation of lung cancer CT screening. Gary Arbique: Research Grant, Toshiba America Medical Systems; Cecelia Brewington: Research Grant, Toshiba America Medical Systems; Di Zhang: Employee, Toshiba America Medical Systems.

  19. Effects of CT dose and nodule characteristics on lung-nodule detectability in a cohort of 90 national lung screening trial patients

    Science.gov (United States)

    Young, Stefano; Lo, Pechin; Hoffman, John M.; Kim, H. J. Grace; Brown, Matthew S.; McNitt-Gray, Michael F.

    2016-03-01

    Lung cancer screening CT is already performed at low dose. There are many techniques to reduce the dose even further, but it is not clear how such techniques will affect nodule detectability. In this work, we used an in-house CAD algorithm to evaluate detectability. 90348 patients and their raw CT data files were drawn from the National Lung Screening Trial (NLST) database. All scans were acquired at ~2 mGy CTDIvol with fixed tube current, 1 mm slice thickness, and B50 reconstruction kernel on a Sensation 64 scanner (Siemens Healthcare). We used the raw CT data to simulate two additional reduced-dose scans for each patient corresponding to 1 mGy (50%) and 0.5 mGy (25%). Radiologists' findings on the NLST reader forms indicated 65 nodules in the cohort, which we subdivided based on LungRADS criteria. For larger category 4 nodules, median sensitivities were 100% at all three dose levels, and mean sensitivity decreased with dose. For smaller nodules meeting the category 2 or 3 criteria, the dose dependence was less obvious. Overall, mean patient-level sensitivity varied from 38.5% at 100% dose to 40.4% at 50% dose, a difference of only 1.9%. However, the false-positive rate quadrupled from 1 per case at 100% dose to 4 per case at 25% dose. Dose reduction affected lung-nodule detectability differently depending on the LungRADS category, and the false-positive rate was very sensitive at sub-screening dose levels. Thus, care should be taken to adapt CAD for the very challenging noise characteristics of screening.

  20. Methodology for estimating radiation dose rates to freshwater biota exposed to radionuclides in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, B.G.; Frank, M.L.; O`Neal, B.R.

    1993-08-01

    The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiation dose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiation doses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiation dose rate to biota to the U.S. Department of Energy`s (DOE`s) recommended dose rate limit of 0.4 mGy h{sup {minus}1} (1 rad d{sup {minus}1}). A dose rate no greater than 0.4 mGy h{sup {minus}1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE`s recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiation dose rate of 0. 1 mGy h{sup {minus}1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic populations should be conducted.

  1. Screen-film versus full-field digital mammography: Radiation dose and image quality in a large teaching hospital

    Directory of Open Access Journals (Sweden)

    Stantić Tomislav J.

    2013-01-01

    Full Text Available The objective of this paper is to measure the radiation dose and image quality in conventional screen-film mammography and full-field digital mammography in women referred to mammography examination. Participants underwent bilateral, two-view screen-film mammography or full-field digital mammography. The visibility of anatomical regions and overall clinical image quality was rated by experienced radiologists. Total of 387 women and 1548 mammograms were enrolled in the study. Image quality was assessed in terms of image quality score, whereas patient dose assessment was performed in terms of mean glandular dose. Average mean glandular dose for cranio-caudal projection was 1.5 mGy and 2.1 mGy in full-field digital mammography and screen-film mammography, respectively. For medio-lateral oblique projection, corresponding values were 2.3 and 2.1 mGy. Overall image quality criteria scoring was 0.82 and 0.99 for screen-film and digital systems, respectively. The scores were in the range from 0.11 to 1.0 for different anatomical structures. Overall, full-field digital mammography was superior both in terms of image quality and dose over the screen-film mammography. The results have indicated that phantom dose values can assist in setting the optimisation activities in mammography and for comparison between mammography units. To obtain accurate diagnostic information with an acceptable radiation dose to breast, it is necessary to periodically perform patient dose and image quality surveys in all mammography units.

  2. CT imaging of congenital lung lesions: effect of iterative reconstruction on diagnostic performance and radiation dose

    Energy Technology Data Exchange (ETDEWEB)

    Haggerty, Jay E.; Smith, Ethan A.; Dillman, Jonathan R. [University of Michigan Health System, Section of Pediatric Radiology, Department of Radiology, C.S. Mott Children' s Hospital, Ann Arbor, MI (United States); Kunisaki, Shaun M. [University of Michigan Health System, Section of Pediatric Surgery, Department of Surgery, C.S. Mott Children' s Hospital, Ann Arbor, MI (United States)

    2015-07-15

    Different iterative reconstruction techniques are available for use in pediatric computed tomography (CT), but these techniques have not been systematically evaluated in infants. To determine the effect of iterative reconstruction on diagnostic performance, image quality and radiation dose in infants undergoing CT evaluation for congenital lung lesions. A retrospective review of contrast-enhanced chest CT in infants (<1 year) with congenital lung lesions was performed. CT examinations were reviewed to document the type of lung lesion, vascular anatomy, image noise measurements and image reconstruction method. CTDI{sub vol} was used to calculate size-specific dose estimates (SSDE). CT findings were correlated with intraoperative and histopathological findings. Analysis of variance and the Student's t-test were used to compare image noise measurements and radiation dose estimates between groups. Fifteen CT examinations used filtered back projection (FBP; mean age: 84 days), 15 used adaptive statistical iterative reconstruction (ASiR; mean age: 93 days), and 11 used model-based iterative reconstruction (MBIR; mean age: 98 days). Compared to operative findings, 13/15 (87%), 14/15 (93%) and 11/11 (100%) lesions were correctly characterized using FBP, ASiR and MBIR, respectively. Arterial anatomy was correctly identified in 12/15 (80%) using FBP, 13/15 (87%) using ASiR and 11/11 (100%) using MBIR. Image noise was less for MBIR vs. ASiR (P < 0.0001). Mean SSDE was different among groups (P = 0.003; FBP = 7.35 mGy, ASiR = 1.89 mGy, MBIR = 1.49 mGy). Congenital lung lesions can be adequately characterized in infants using iterative CT reconstruction techniques while maintaining image quality and lowering radiation dose. (orig.)

  3. A cross-platform survey of CT image quality and dose from routine abdomen protocols and a method to systematically standardize image quality

    Science.gov (United States)

    Favazza, Christopher P.; Duan, Xinhui; Zhang, Yi; Yu, Lifeng; Leng, Shuai; Kofler, James M.; Bruesewitz, Michael R.; McCollough, Cynthia H.

    2015-11-01

    Through this investigation we developed a methodology to evaluate and standardize CT image quality from routine abdomen protocols across different manufacturers and models. The influence of manufacturer-specific automated exposure control systems on image quality was directly assessed to standardize performance across a range of patient sizes. We evaluated 16 CT scanners across our health system, including Siemens, GE, and Toshiba models. Using each practice’s routine abdomen protocol, we measured spatial resolution, image noise, and scanner radiation output (CTDIvol). Axial and in-plane spatial resolutions were assessed through slice sensitivity profile (SSP) and modulation transfer function (MTF) measurements, respectively. Image noise and CTDIvol values were obtained for three different phantom sizes. SSP measurements demonstrated a bimodal distribution in slice widths: an average of 6.2  ±  0.2 mm using GE’s ‘Plus’ mode reconstruction setting and 5.0  ±  0.1 mm for all other scanners. MTF curves were similar for all scanners. Average spatial frequencies at 50%, 10%, and 2% MTF values were 3.24  ±  0.37, 6.20  ±  0.34, and 7.84  ±  0.70 lp cm-1, respectively. For all phantom sizes, image noise and CTDIvol varied considerably: 6.5-13.3 HU (noise) and 4.8-13.3 mGy (CTDIvol) for the smallest phantom; 9.1-18.4 HU and 9.3-28.8 mGy for the medium phantom; and 7.8-23.4 HU and 16.0-48.1 mGy for the largest phantom. Using these measurements and benchmark SSP, MTF, and image noise targets, CT image quality can be standardized across a range of patient sizes.

  4. V/P SPECT as a diagnostic tool for pregnant women with suspected pulmonary embolism

    Energy Technology Data Exchange (ETDEWEB)

    Bajc, Marika; Olsson, Berit; Joegi, Jonas [Skaane University Hospital and Lund University, Clinical Physiology and Nuclear Medicine, Lund (Sweden); Gottsaeter, Anders [Skaane University Hospital, Vascular Diseases, Malmoe (Sweden); Hindorf, Cecilia [Skaane University Hospital, Radiation Physics, Lund (Sweden)

    2015-07-15

    The purpose of the study was to assess the prevalence of pulmonary embolism (PE) and other lung diseases among pregnant women with suspected PE and to calculate the radiation exposure to patient and fetus in this population. As a secondary aim, we evaluated the negative predictive value of a normal ventilation/perfusion single photon emission computed tomography (V/P SPECT) examination in pregnancy. We studied all 127 pregnant women who had suspected PE and had undergone V/P SPECT at our institution in the course of a 5-year period. Radiation exposure to patient and fetus and the negative predictive value of a normal V/P SPECT examination were also measured. V/P SPECT identified PE in 11 women (9 %). Moreover, in 15 women (12 %) the examination revealed pneumonia (in 2 cases in addition to PE) and in 1 woman signs of airway obstruction were revealed. Among the 116/127 women (91 %) where PE was ruled out by V/P SPECT, none was diagnosed subsequently with PE or deep venous thrombosis (DVT) during the same pregnancy or puerperal period. For P SPECT, the calculated fetal absorbed dose was < 0.6 mGy,and the calculated breast absorbed dose 0.6 mGy. For V SPECT, the calculated fetal absorbed dose was < 0.014 mGy and the breast absorbed dose 0.25 mGy. The prevalence of PE was low (9 %) among pregnant women with suspected disease. Pneumonia was diagnosed in 12 % of patients. The negative predictive value of V/P SPECT was high, and the radiation exposure from V/P SPECT was low both for fetus and patient. (orig.)

  5. Thermoluminescence characteristics of Zn(BO2)2:Ce3+ under beta irradiation.

    Science.gov (United States)

    Kucuk, Nil; Kucuk, Ilker; Yüksel, Mehmet; Topaksu, Mustafa

    2016-03-01

    In this study, the thermoluminescence (TL) characteristics of undoped and various Ce(3) (+)-doped Zn(BO2)2 powder samples excited by beta irradiation are reported for the first time. Zn(BO2)2:Ce(3+) powder samples were prepared by the nitric acid method (NAM) using the starting oxides [zinc oxide (ZnO), boric acid (H3BO3) and doped element oxide (CeO2)]. The formations of the obtained samples were confirmed by an X-ray diffraction study. Dose responses of Ce(3) (+)-doped Zn(BO2)2 samples were investigated after the beta irradiation in the dose range from 143 mGy to 60 Gy. All TL measurements were made on using an automated Risø TL/OSL DA-20 reader. TL emission was detected through a filter pack (Schott BG-39 and Corning 7-59) transmitting between 330 and 480 nm. TL glow curves were obtained using a constant heating rate of 5°C s(-1) from room temperature (RT) to 450°C in an N2 atmosphere. The dose response and minimum detectable dose (MDD) values of the samples were determined. The dose responses of all the samples tested exhibited a superlinear behaviour. MDD value of 4 % Ce(3) (+)-doped Zn(BO2)2 sample, which shows a high temperature peak at about 230°C, was determined as 96 mGy. MDD values for 1, 2, 3, 5 and 10 % Ce(3) (+)-doped Zn(BO2)2 samples were also determined as 682, 501, 635, 320 and 824 mGy, respectively. The trap parameters of undoped and 4 % Ce(3) (+)-doped Zn(BO2)2 samples were estimated by the computerised glow curve deconvolution method.

  6. Real-time eye lens dose monitoring during cerebral angiography procedures.

    Science.gov (United States)

    Safari, M J; Wong, J H D; Kadir, K A A; Thorpe, N K; Cutajar, D L; Petasecca, M; Lerch, M L F; Rosenfeld, A B; Ng, K H

    2016-01-01

    To develop a real-time dose-monitoring system to measure the patient's eye lens dose during neuro-interventional procedures. Radiation dose received at left outer canthus (LOC) and left eyelid (LE) were measured using Metal-Oxide-Semiconductor Field-Effect Transistor dosimeters on 35 patients who underwent diagnostic or cerebral embolization procedures. The radiation dose received at the LOC region was significantly higher than the dose received by the LE. The maximum eye lens dose of 1492 mGy was measured at LOC region for an AVM case, followed by 907 mGy for an aneurysm case and 665 mGy for a diagnostic angiography procedure. Strong correlations (shown as R(2)) were observed between kerma-area-product and measured eye doses (LOC: 0.78, LE: 0.68). Lateral and frontal air-kerma showed strong correlations with measured dose at LOC (AKL: 0.93, AKF: 0.78) and a weak correlation with measured dose at LE. A moderate correlation was observed between fluoroscopic time and dose measured at LE and LOC regions. The MOSkin dose-monitoring system represents a new tool enabling real-time monitoring of eye lens dose during neuro-interventional procedures. This system can provide interventionalists with information needed to adjust the clinical procedure to control the patient's dose. Real-time patient dose monitoring helps interventionalists to monitor doses. Strong correlation was observed between kerma-area-product and measured eye doses. Radiation dose at left outer canthus was higher than at left eyelid.

  7. A survivin-associated adaptive response in radiation therapy.

    Science.gov (United States)

    Grdina, David J; Murley, Jeffrey S; Miller, Richard C; Mauceri, Helena J; Sutton, Harold G; Li, Jian Jian; Woloschak, Gayle E; Weichselbaum, Ralph R

    2013-07-15

    Adaptive responses can be induced in cells by very low doses of ionizing radiation resulting in an enhanced resistance to much larger exposures. The inhibitor of apoptosis protein, survivin, has been implicated in many adaptive responses to cellular stress. Computerized axial tomography used in image-guided radiotherapy to position and monitor tumor response uses very low radiation doses ranging from 0.5 to 100 mGy. We investigated the ability of these very low radiation doses administered along with two 2 Gy doses separated by 24 hours, a standard conventional radiotherapy dosing schedule, to initiate adaptive responses resulting in the elevation of radiation resistance in exposed cells. Human colon carcinoma (RKO36), mouse sarcoma (SA-NH), along with transformed mouse embryo fibroblasts, wild type or cells lacking functional tumor necrosis factor receptors 1 and 2 were used to assess their relative ability to express an adaptive response when grown either to confluence in vitro or as tumors in the flank of C57BL/6 mice. The survival of each of these cells was elevated from 5% to 20% (P ≤ 0.05) as compared to cells not receiving a 100 mGy or lesser dose. In addition, the cells exposed to 100 mGy exhibited elevations in survivin levels, reductions in apoptosis frequencies, and loss of an adaptive response if transfected with survivin siRNA. This survivin-mediated adaptive response has the potential for affecting outcomes if regularly induced throughout a course of image guided radiation therapy. ©2013 AACR.

  8. Thyroid absorbed dose using TLDs during mammography

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez A, M.; Melendez L, M. [IPN, Centro de Investigacion y de Estudios Avanzados, Av. IPN 2508, Col. San Pedro Zacatenco, 07360 Mexico D. F. (Mexico); Davila M, P., E-mail: biomedica.sst@gmail.com [UNEME-DEDICAM de Ciudad Victoria, Circuito Medico s/n, 87087 Ciudad Victoria, Tamaulipas (Mexico)

    2015-10-15

    Full text: In this study, the mean glandular dose (MGD) and the thyroid dose (D Thy) were measured in 200 women screened with mammography in Cranio caudal (Cc) and mediolateral oblique projections. All mammograms were performed with Giotto-Ims (6000-14-M2 Model) equipment, which was verified to meet the criteria of quality of NOM-229-Ssa-2002. During audits performance and HVL, for each anode filter combinations was measured with the camera Radcal mammography equipment 10 X 6-6M (HVL = 0.26 mm Al). D Thy measurements were performed with TLD dosimeters (LiF:Mn) , that were read with the Harshaw 3500 TLD reader. The MGD, was obtained according to the UK and European protocols for mammographic dosimetry using a plane parallel chamber (Standard Imaging, Model A-600) calibrated by a radiation beam UW-23-Mo (= 0.279 mm Al HVL). A comparative statistical analysis was carried out with the measured MGD and D thy. The thyroid mean dose was 0.063 mGy and 0.078 mGy for Cc and mediolateral oblique respectively. There is a linear correlation between the MGD and the D Thy slightly influenced by the anode-filter combination. Using a 95% for the confidence interval in MGD (1.07 mGy), the 90% of measurements are in agreement with the established uncertainty limits. The D Thy are lower than the MGD. There is no risk for cancer induction in thyroid in women due to mammography screening. (Author)

  9. Retrospective biodosimetry with small tooth enamel samples using K-Band and X-Band

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Jorge A. [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto, Sao Paulo (Brazil); Kinoshita, Angela [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto, Sao Paulo (Brazil); Universidade Sagrado Coracao - USC, 17011-160 Bauru, Sao Paulo (Brazil); Leonor, Sergio J. [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto, Sao Paulo (Brazil); Belmonte, Gustavo C. [Universidade Sagrado Coracao - USC, 17011-160 Bauru, Sao Paulo (Brazil); Baffa, Oswaldo, E-mail: baffa@usp.br [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto, Sao Paulo (Brazil)

    2011-09-15

    In an attempt to make the in vitro electron spin resonance (ESR) retrospective dosimetry of the tooth enamel a lesser invasive method, experiments using X-Band and K-Band were performed, aiming to determine conditions that could be used in cases of accidental exposures. First, a small prism from the enamel was removed and ground with an agate mortar and pestle until particles reach a diameter of approximately less than 0.5 mm. This enamel extraction process resulted in lower signal artifact compared with the direct enamel extraction performed with a diamond burr abrasion. The manual grinding of the enamel does not lead to any induced ESR signal artifact, whereas the use of a diamond burr at low speed produces a signal artifact equivalent to the dosimetric signal induced by a dose of 500 mGy of gamma irradiation. A mass of 25 mg of enamel was removed from a sound molar tooth previously irradiated in vitro with a dose of 100 mGy. This amount of enamel was enough to detect the dosimetric signal in a standard X-Band spectrometer. However using a K-Band spectrometer, samples mass between 5 and 10 mg were sufficient to obtain the same sensitivity. An overall evaluation of the uncertainties involved in the process in this and other dosimetric assessments performed at our laboratory indicates that it is possible at K-Band to estimate a 100 mGy dose with 25% accuracy. In addition, the use of K-Band also presented higher sensitivity and allowed the use of smaller sample mass in comparison with X-Band. Finally, the restoration process performed on a tooth after extraction of the 25 mg of enamel is described. This was conducted by dental treatment using photopolymerizable resin which enabled complete recovery of the tooth from the functional and aesthetic viewpoint showing that this procedure can be minimally invasive.

  10. Influence of a chronic {sup 90}Sr contamination by ingestion on the hematopoietic, immune and bone systems; Influence d'une contamination chronique par ingestion de {sup 90}Sr sur les systemes hematopoietique, immunitaire et osseux

    Energy Technology Data Exchange (ETDEWEB)

    Synhaeve, Nicholas

    2011-12-15

    Strontium 90 ({sup 90}Sr) is a radionuclide of anthropogenic origin released in large quantities in the environment as a result of nuclear atmospheric tests or accidents at nuclear facilities. {sup 90}Sr persists on a long-term basis in the environment, leading to chronic contamination by ingestion of populations living on contaminated territories. The induction of bone tumours associated with the fixation of {sup 90}Sr has been widely described. However, the occurrence of non-cancer effects is much less known. We used a mouse model with chronic contamination by ingestion of water containing 20 kBq/l of {sup 90}Sr. A bio-kinetic study confirmed the accumulation of {sup 90}Sr in the bones, with an increased rate of accumulation during bone growth. This accumulation was higher in the bones of females than in males. The whole-body absorbed doses ranged from 0.33 {+-} 0.06 mGy (birth) to 10.6 {+-} 0.1 mGy (20 weeks). The absorbed dose for the skeleton was up to 55 mGy. Ingestion of {sup 90}Sr induced a change in the expression of genes inducing an imbalance in favour of bone resorption, but without effect on bone morphology. No significant effect was observed for the hematopoietic system. On the other hand, minor modifications were observed for the immune system. To evaluate the functionality of the immune system, a vaccination test with TT and KLH antigens was used. Results showed in contaminated animals a significant decrease in the production of specific immunoglobulins, changes in the Th1/Th2 balance in the spleen and a disrupted B lymphocyte differentiation. These results improve the understanding of some of the noncancerous consequences of chronic exposure at low dose of radionuclides with a long half-life, which can be accidentally released. (author)

  11. SU-F-SPS-03: Direct Measurement of Organ Doses Resulting From Head and Cervical Spine Trauma CT Protocols

    Energy Technology Data Exchange (ETDEWEB)

    Carranza, C; Lipnharski, I; Quails, N; Correa, N; Rill, L; Arreola, M [University of Florida, Gainesville, FL (United States)

    2016-06-15

    Purpose: This retrospective study analyzes the exposure history of emergency department (ED) patients undergoing head and cervical spine trauma computed tomography (CT) studies. This study investigated dose levels received by trauma patients and addressed any potential concerns regarding radiation dose issues. Methods: Under proper IRB approval, a cohort of 300 trauma cases of head and cervical spine trauma CT scans received in the ED was studied. The radiological image viewing software of the hospital was used to view patient images and image data. The following parameters were extracted: the imaging history of patients, the reported dose metrics from the scanner including the volumetric CT Dose Index (CTDIvol) and Dose Length Product (DLP). A postmortem subject was scanned using the same scan techniques utilized in a standard clinical head and cervical spine trauma CT protocol with 120 kVp and 280 mAs. The CTDIvol was recorded for the subject and the organ doses were measured using optically stimulated luminescent (OSL) dosimeters. Typical organ doses to the brain, thyroid, lens, salivary glands, and skin, based on the cadaver studies, were then calculated and reported for the cohort. Results: The CTDIvol reported by the CT scanner was 25.5 mGy for the postmortem subject. The average CTDIvol from the patient cohort was 34.1 mGy. From these metrics, typical average organ doses in mGy were found to be: Brain (44.57), Thyroid (33.40), Lens (82.45), Salivary Glands (61.29), Skin (47.50). The imaging history of the cohort showed that on average trauma patients received 26.1 scans over a lifetime. Conclusion: The average number of scans received on average by trauma ED patients shows that radiation doses in trauma patients may be a concern. Available dose tracking software would be helpful to track doses in trauma ED patients, highlighting the importance of minimizing unnecessary scans and keeping doses ALARA.

  12. Radiation effects on the properties of a polyurethane/epoxy graft interpenetrating polymer network. An investigation into the application of polymers in the fabrication of containers to store radioactive waste

    Energy Technology Data Exchange (ETDEWEB)

    Mortley, A. [Royal Military College of Canada, Dept. of Chemistry and Chemical Engineering, Kingston, Ontario (Canada)]. E-mail: aba.mortley@rmc.ca

    2005-07-01

    The toughening effects of a castor oil based polyurethane on an epoxy matrix, by means of an interpenetrating network (IPN) was investigated. In addition, the radiation effects of two PU/EP graft-IPNs, 19/81 and 27/73 PU/EP graft-IPNs, were examined so that possible application of these materials in the fabrication of containers to store radioactive waste over long periods of time could be considered. The polyurethane/epoxy graft-IPN was made by a sequential method of synthesis, in which the polyurethane prepolymer was prepared before the addition of the epoxy resin and crosslinker. The PU/EP graft-IPN specimens were subjected to several doses of radiation that ranged from 0.11 MGy to 3.0 MGy, using the SLOWPOKE-2 nuclear reactor at Royal Military College of Canada (RMC). The irradiated and unirradiated IPN samples were then subjected to a battery of chemical and mechanical tests to determine the effects of radiation. Based on the observations from the chemical and mechanical tests, it has been established that the 19/81 PU/EP graft-IPN is suitable for applications in radiation environments below a dose of 1.5 MGy. The 27/73 PU/EP graft-IPN is unsuitable for radiation applications at low doses, however it shows a noticeable increase in chemical and mechanical properties with increasing accumulated dose. Past work at RMC has shown the beneficial properties of a ThO{sub 2} filler within the radioactive waste container. With regard to the design of the disposal containers, with the aid of aThO{sub 2} filler, it is the opinion from the present work that the graft-IPNs could potentially be used in the fabrication of containers to store low and intermediate level radioactive waste, as well as spent nuclear fuel and high level radioactive waste. (author)

  13. Methodology for estimating radiation dose rates to freshwater biota exposed to radionuclides in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, B.G.; Frank, M.L.; O`Neal, B.R.

    1993-08-01

    The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiation dose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiation doses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiation dose rate to biota to the U.S. Department of Energy`s (DOE`s) recommended dose rate limit of 0.4 mGy h{sup {minus}1} (1 rad d{sup {minus}1}). A dose rate no greater than 0.4 mGy h{sup {minus}1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE`s recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiation dose rate of 0. 1 mGy h{sup {minus}1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic populations should be conducted.

  14. Effect of the menstrual cycle on inflammatory cytokines in the periodontium.

    Science.gov (United States)

    Khosravisamani, M; Maliji, G; Seyfi, S; Azadmehr, A; Abd Nikfarjam, B; Madadi, S; Jafari, S

    2014-12-01

    The effects of different levels of steroid hormones, as experienced during puberty, pregnancy and menopause, on the periodontium have been demonstrated, but changes in sex hormone levels during the menstrual cycle, and the influence of these changes on the periodontium, remain unresolved. The aim of this study was to investigate the effect of the menstrual cycle on the levels of interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) in gingival crevicular fluid and on periodontal clinical parameters, including the gingival bleeding index (GBI) and the modified gingival index (MGI), in periodontally healthy women. Twenty-seven periodontally healthy women with a regular menstrual cycle were included in the study. Clinical parameters, including the GBI, the MGI and the simplified oral health index, were recorded during menstruation, ovulation and premenstruation phases (e.g. on days 1-2, 12-14 and 22-24, respectively) of the menstrual cycle. Gingival crevicular fluid and unstimulated saliva were collected, at each study phase, for assessment of IL-1β, TNF-α, estrogen and progesterone. Both the GBI and the MGI increased significantly during the menstrual cycle, and were significantly higher during ovulation than during menstruation or premenstruation (p menstrual cycle ( p = 0.18). The levels of IL-1β and TNF-α increased during the different phases of the menstrual cycle, but only the change in the TNF-α concentration was significant ( p menstrual cycle influence the periodontium and induce inflammatory conditions. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. The 1st Nuclear Test in the former USSR of 29 August 1949: Comparison of individual dose estimates by modeling with EPR retrospective dosimetry and luminescence retrospective dosimetry data for Dolon village, Kazakhstan

    Energy Technology Data Exchange (ETDEWEB)

    Stepanenko, V.F. [Medical Radiological Research Center of RAMS, 4 Korolev Str., Obninsk 249036 (Russian Federation); Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi 1-2-3, Minami-ku, Hiroshima 734-8553 (Japan)], E-mail: mrrc@obninsk.ru; Hoshi, M. [Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi 1-2-3, Minami-ku, Hiroshima 734-8553 (Japan); Ivannikov, A.I. [Medical Radiological Research Center of RAMS, 4 Korolev Str., Obninsk 249036 (Russian Federation); Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi 1-2-3, Minami-ku, Hiroshima 734-8553 (Japan); Bailiff, I.K. [Luminescence Dating and Dosimetry Laboratory, University of Durham, South Road, Durham, DHI 3LE (United Kingdom); Zhumadilov, K. [Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi 1-2-3, Minami-ku, Hiroshima 734-8553 (Japan); Skvortsov, V.G. [Medical Radiological Research Center of RAMS, 4 Korolev Str., Obninsk 249036 (Russian Federation); Argembaeva, R. [Scientifical Research Institute for Radiation Medicine, 258, Gagarina Str., P.B. 49, Semipalatinsk 490026 (Kazakhstan); Tsyb, A.F. [Medical Radiological Research Center of RAMS, 4 Korolev Str., Obninsk 249036 (Russian Federation)

    2007-07-15

    Three methods of individual dose reconstruction, namely dose calculations based on the available archive data and on the individual questioning of inhabitants, EPR dosimetry in human tooth enamel, and retrospective luminescence dosimetry (RLD) with quartz inclusions in the bricks were applied for assessment of accumulated external doses in Dolon village (Kazakhstan), which is one of the most affected settlements as a result of 29.08.1949 nuclear test at Semipalatinsk nuclear test site. Dose values obtained by EPR and RLD methods were compared with computed dose values. The available data on soil contamination with {sup 137}Cs and {sup 239+240}Pu in the vicinity and inside Dolon village were used for interpretation of the results of comparison. Based on a calculated value of 2260 mGy for the dose in the air along the central axis of the trace located NW of Dolon, the doses in the air over whole village and for the south-eastern part of the village containing the RLD sampling points were estimated as 775{+-}40 and 645{+-}70mGy, respectively, the latter correlates well with the RLD dose value of 460{+-}92mGy. The 'upper level' of the mean 'shielding and behavior' factor of dose reduction for inhabitants of Dolon village was estimated as 0.28{+-}0.07; this was performed by comparing the individual EPR tooth enamel doses with the calculated mean dose for the settlement. The individual dose estimates by EPR dosimetry were compared with individual dose values obtained by modeling. Uncertainties of the calculated individual doses were evaluated using Monte Carlo simulations. The individual dose estimates by EPR method are lower in comparison with mean computed doses and with RLD data, but they are in a good consistency with computed individual dose values in Dolon village based on the results of individual questioning with account of individual 'shielding and behavior' factors.

  16. Chronic low-dose exposure in the Techa River cohort. Risk of mortality from circulatory diseases

    Energy Technology Data Exchange (ETDEWEB)

    Krestinina, Lyudmila Yurievna; Epifanova, Svetlana; Silkin, Stanislav; Mikryukova, Lyudmila; Degteva, Marina; Shagina, Natalia; Akleyev, Alexander [Urals Research Center for Radiation Medicine, Chelyabinsk (Russian Federation)

    2013-03-15

    The aim of the present study was to analyze the mortality from circulatory diseases for about 30,000 members of the Techa River cohort over the period 1950-2003, and to investigate how these rates depend on radiation doses. This population received both external and internal exposures from {sup 90}Sr, {sup 89}Sr, {sup 137}Cs, and other uranium fission products as a result of waterborne releases from the Mayak nuclear facility in the Southern Urals region of the Russian Federation. The analysis included individualized estimates of the total (external plus internal) absorbed dose in muscle calculated based on the Techa River Dosimetry System 2009. The cohort-average dose to muscle tissue was 35 mGy, and the maximum dose was 510 mGy. Between 1950 and 2003, 7,595 deaths from circulatory diseases were registered among cohort members with 901,563 person years at risk. Mortality rates in the cohort were analyzed using a simple parametric excess relative risk (ERR) model. For all circulatory diseases, the estimated excess relative risk per 100 mGy with a 15-year lag period was 3.6 % with a 95 % confidence interval of 0.2-7.5 %, and for ischemic heart disease it was 5.6 % with a 95 % confidence interval of 0.1-11.9 %. A linear ERR model provided the best fit. Analyses with a lag period shorter than 15 years from the beginning of exposure did not reveal any significant risk of mortality from either all circulatory diseases or ischemic heart disease. There was no evidence of an increased mortality risk from cerebrovascular disease (p > 0.5). These results should be regarded as preliminary, since they will be updated after adjustment for smoking and alcohol consumption. (orig.)

  17. Imaging the Parasinus Region with a Third-Generation Dual-Source CT and the Effect of Tin Filtration on Image Quality and Radiation Dose.

    Science.gov (United States)

    Lell, M M; May, M S; Brand, M; Eller, A; Buder, T; Hofmann, E; Uder, M; Wuest, W

    2015-07-01

    CT is the imaging technique of choice in the evaluation of midface trauma or inflammatory disease. We performed a systematic evaluation of scan protocols to optimize image quality and radiation exposure on third-generation dual-source CT. CT protocols with different tube voltage (70-150 kV), current (25-300 reference mAs), prefiltration, pitch value, and rotation time were systematically evaluated. All images were reconstructed with iterative reconstruction (Advanced Modeled Iterative Reconstruction, level 2). To individually compare results with otherwise identical factors, we obtained all scans on a frozen human head. Conebeam CT was performed for image quality and dose comparison with multidetector row CT. Delineation of important anatomic structures and incidental pathologic conditions in the cadaver head was evaluated. One hundred kilovolts with tin prefiltration demonstrated the best compromise between dose and image quality. The most dose-effective combination for trauma imaging was Sn100 kV/250 mAs (volume CT dose index, 2.02 mGy), and for preoperative sinus surgery planning, Sn100 kV/150 mAs (volume CT dose index, 1.22 mGy). "Sn" indicates an additional prefiltration of the x-ray beam with a tin filter to constrict the energy spectrum. Exclusion of sinonasal disease was possible with even a lower dose by using Sn100 kV/25 mAs (volume CT dose index, 0.2 mGy). High image quality at very low dose levels can be achieved by using a Sn100-kV protocol with iterative reconstruction. The effective dose is comparable with that of conventional radiography, and the high image quality at even lower radiation exposure favors multidetector row CT over conebeam CT. © 2015 by American Journal of Neuroradiology.

  18. In vivo quantification of {sup 18}F-Fdg uptake in human placenta during early pregnancy

    Energy Technology Data Exchange (ETDEWEB)

    Zanotti-Fregonara, P.; Jan, S.; Trebossen, R.; Maroy, R. [CEA, DSV, I2BM, SHFJ, F-91401 Orsay (France); Champion, C. [Univ Paul Verlaine Metz, Lab Phys Mol et Collis, Inst Phys, Metz (France); Hindie, E. [Hop St Antoine, AP-HP, F-75571 Paris (France); Hindie, E. [Univ Paris 07, IMDCT, IUH, Ecole Doctorale B2T, F-75221 Paris (France)

    2008-07-01

    {sup 18}F-FDG is the most widely used PET radiopharmaceutical. Nevertheless, no data for {sup 18}F-FDG uptake in the human placenta have been reported. We recently reported on embryo dosimetry in a woman who underwent an {sup 18}F-FDG PET/CT scan during early pregnancy. In the present work we attempt an in vivo quantification of the {sup 18}F-FDG uptake by the placenta. The 27-y-old woman received 320 MBq of {sup 18}F-FDG for a follow-up study for Hodgkin's lymphoma and was later discovered to be pregnant (embryo age 8 wk). Imaging started 1 h after injection. The maximum placental tissue uptake (SUVmax) was 2.5. This value was conservatively attributed to the entire placental volume, i.e., 45 mL, a value representative of the average dimensions of a normal placenta at 8 wk. On the basis of these measurements, placenta {sup 18}F-FDG uptake in our patient was 0.19% of the injected activity. A Monte Carlo simulation was used to derive the photon dose to the embryo from the placenta (0.022 * 10{sup -2} mGy per MBq of injected {sup 18}F-FDG) and from the surrounding amniotic fluid (0.017 * 10{sup -2} mGy MBq{sup -1}). This increases our previously calculated dose (3.3 * 10{sup -2} mGy MBq{sup -1}) by only a small fraction (1.18%), which does not justify modifying the previous estimate given the overall uncertainties. (authors)

  19. Evaluation of the efficacy of a polyherbal mouthwash containing Zingiber officinale, Rosmarinus officinalis and Calendula officinalis extracts in patients with gingivitis: A randomized double-blind placebo-controlled trial.

    Science.gov (United States)

    Mahyari, Saman; Mahyari, Behnam; Emami, Seyed Ahmad; Malaekeh-Nikouei, Bizhan; Jahanbakhsh, Seyedeh Pardis; Sahebkar, Amirhossein; Mohammadpour, Amir Hooshang

    2016-02-01

    Gingivitis is a highly prevalent periodontal disease resulting from microbial infection and subsequent inflammation. The efficacy of herbal preparations in subjects with gingivitis has been reported in some previous studies. To investigate the efficacy of a polyherbal mouthwash containing hydroalcoholic extracts of Zingiber officinale, Rosmarinus officinalis and Calendula officinalis (5% v/w) compared with chlorhexidine and placebo mouthwashes in subjects with gingivitis. Sixty patients participated in this randomized double-blind placebo-controlled trial and were randomly assigned to the polyherbal mouthwash (n = 20), chlorhexidine mouthwash (n = 20) or placebo mouthwash (n = 20). Participants were instructed to use the mouthwash twice a day (after breakfast and dinner) for 30 s for a period of two weeks. Gingival and plaque indices were assessed using MGI, GBI and MQH scales at baseline, day 7 and day 14 of the trial. There were significant improvements in all assessed efficacy measures i.e. MGI, GBI and MQH scores from baseline to the end of trial in both polyherbal and chlorhexidine mouthwash groups; however, the scores remained statistically unchanged in the placebo group. MGI, BGI and MQH scores in the treatment groups were significantly lower compared with those of the control group at both day 7 and day 14 of the trial. However, there was no significant difference between the polyherbal and chlorhexidine groups, neither at day 7 nor day 14 of the trial. Polyherbal mouthwash was safe and there was neither report of adverse reactions, nor any drop-out during the course of study. Polyherbal mouthwash containing hydroalcoholic extracts of Z. officinale, R. officinalis and C. officinalis (5%) was effective in the treatment of gingivitis and its efficacy was comparable to that of chlorhexidine mouthwash. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Solid state radiolysis of amino acids in an astrochemical perspective

    Science.gov (United States)

    Cataldo, Franco; Angelini, Giancarlo; Iglesias-Groth, Susana; Manchado, Arturo

    2011-01-01

    The aliphatic amino acids L-alanine and L-leucine and the aromatic amino acids L-phenylalanine, L-tyrosine and L-tryptophan were irradiated in the solid state to a dose of 3.2 MGy. The degree of decomposition was measured by differential scanning calorimetry (DSC). Furthermore the degree of radioracemization was measured by optical rotatory dispersion (ORD) spectroscopy. From the DSC measurement a radiolysis rate constant k and the half life T1/2 for each amino acid have been determined and extrapolated to a dose of 14 MGy, which corresponds to the expected total dose delivered by the decay of radionuclides to the organic molecules present in comets and asteroids in 4.6×109 years, the age of the Solar System. It is shown that all the amino acids studied can survive a radiation dose of 14 MGy although they are reduced to 1/4-1/5 of their original value they had at the beginning of the history of the Solar System. Consequently, the amount of alanine or leucine found today in the meteorites known as carbonaceous chondrites is just 1/4-1/5 of the amount originally present at the epoch of the formation of the Solar System 4.6×109 years ago. Among the amino acids studied, tyrosine shows the highest radiation resistance while tryptophan does not combine its relatively high radiation resistance with an elevated level of radioracemization resistance. Apart from the exception of tryptophan, it is shown that the radiolysis rate constants k of all the amino acids studied are in reasonable agreement with the radioracemization rate constant krac.

  1. No clinically relevant effect on cognitive outcomes after low-dose radiation to the infant brain: a population-based cohort study in Sweden.

    Science.gov (United States)

    Blomstrand, Malin; Holmberg, Erik; Aberg, Maria A I; Lundell, Marie; Björk-Eriksson, Thomas; Karlsson, Per; Blomgren, Klas

    2014-09-01

    While the detrimental effects of cranial radiotherapy on the developing brain are well known, the effects on cognitive performance of low doses of ionizing radiation is less studied. We performed a population-based cohort study to determine whether low doses of ionizing radiation to the brain in infancy affects cognitive function later in life. Further we hypothesized that the dose to the hippocampus predicts cognitive late side effects better than the anterior or the posterior brain doses. During 1950-1960 3860 boys were treated with radiation in Sweden for cutaneous hemangiomas before the age of 18 months. Of these, 3030 were analyzed for military test scores at the age of 18 years and 2559 for the highest obtained educational level. Logical, spatial and technical test scores were not affected by increasing irradiation doses. The verbal test scores displayed a significant trend for decreasing scores with increasing doses to the hippocampus (p = 0.005). However, the absolute mean difference between the zero dose and the highest dose category (median 680 mGy) was very small, only 0.64 stanine points, and the significance was dependent on the highest dose category, containing few subjects. The educational level was not affected by brain irradiation. Overall, the hippocampal dose was a better predictor of late cognitive side effects than the doses to the anterior or the posterior brain. In conclusion, there was no decrease in logical, spatial and technical verbal or global test scores after ionizing radiation doses up to 250 mGy, but a subtle decrease in verbal test scores if the highest dose category was included (median 680 mGy). However, the clinical relevance of this decline in the highest dose group is questionable, since we could not find any effect on the highest obtained educational level.

  2. Solid state radiolysis of amino acids in an astrochemical perspective

    Energy Technology Data Exchange (ETDEWEB)

    Cataldo, Franco, E-mail: franco.cataldo@fastwebnet.i [Istituto Nazionale di Astrofisica-Osservatorio Astrofisica di Catania, Via S. Sofia 78, 95123 Catania (Italy); Lupi Chemical Research, Via Casilina 1626/A, 00133 Rome (Italy); Angelini, Giancarlo [Istituto di Metodologie Chimiche, CNR, Via Salaria Km 29300, 00016 Monterotondo Stazione, Rome (Italy); Iglesias-Groth, Susana [Instituto de Astrofisica de Canarias, Via Lactea s/n, E-38200, La Laguna, Tenerife (Spain); Manchado, Arturo [Instituto de Astrofisica de Canarias, Via Lactea s/n, E-38200, La Laguna, Tenerife (Spain) and CSIC (Spain)

    2011-01-15

    The aliphatic amino acids L-alanine and L-leucine and the aromatic amino acids L-phenylalanine, L-tyrosine and L-tryptophan were irradiated in the solid state to a dose of 3.2 MGy. The degree of decomposition was measured by differential scanning calorimetry (DSC). Furthermore the degree of radioracemization was measured by optical rotatory dispersion (ORD) spectroscopy. From the DSC measurement a radiolysis rate constant k and the half life T{sub 1/2} for each amino acid have been determined and extrapolated to a dose of 14 MGy, which corresponds to the expected total dose delivered by the decay of radionuclides to the organic molecules present in comets and asteroids in 4.6x10{sup 9} years, the age of the Solar System. It is shown that all the amino acids studied can survive a radiation dose of 14 MGy although they are reduced to 1/4-1/5 of their original value they had at the beginning of the history of the Solar System. Consequently, the amount of alanine or leucine found today in the meteorites known as carbonaceous chondrites is just 1/4-1/5 of the amount originally present at the epoch of the formation of the Solar System 4.6x10{sup 9} years ago. Among the amino acids studied, tyrosine shows the highest radiation resistance while tryptophan does not combine its relatively high radiation resistance with an elevated level of radioracemization resistance. Apart from the exception of tryptophan, it is shown that the radiolysis rate constants k of all the amino acids studied are in reasonable agreement with the radioracemization rate constant k{sub rac}.

  3. Low-dose radiation prevents type 1 diabetes-induced cardiomyopathy via activation of AKT mediated anti-apoptotic and anti-oxidant effects.

    Science.gov (United States)

    Zhang, Fangfang; Lin, Xiufei; Yu, Lechu; Li, Weihua; Qian, Dingliang; Cheng, Peng; He, Luqing; Yang, Hong; Zhang, Chi

    2016-07-01

    We investigated whether low-dose radiation (LDR) can prevent late-stage diabetic cardiomyopathy and whether this protection is because of the induction of anti-apoptotic and anti-oxidant pathways. Streptozotocin-induced diabetic C57BL/6J mice were treated with/without whole-body LDR (12.5, 25, or 50 mGy) every 2 days. Twelve weeks after onset of diabetes, cardiomyopathy was diagnosed characterized by significant cardiac dysfunction, hypertrophy and histopathological abnormalities associated with increased oxidative stress and apoptosis, which was prevented by LDR (25 or 50 mGy only). Low-dose radiation-induced cardiac protection also associated with P53 inactivation, enhanced Nrf2 function and improved Akt activation. Next, for the mechanistic study, mouse primary cardiomyocytes were treated with high glucose (33 mmol/l) for 24 hrs and during the last 15 hrs bovine serum albumin-conjugated palmitate (62.5 μmol/l) was added into the medium to mimic diabetes, and cells were treated with LDR (25 mGy) every 6 hrs during the whole process of HG/Pal treatment. Data show that blocking Akt/MDM2/P53 or Akt/Nrf2 pathways with small interfering RNA of akt, mdm2 and nrf2 not only prevented LDR-induced anti-apoptotic and anti-oxidant effects but also prevented LDR-induced suppression on cardiomyocyte hypertrophy and fibrosis against HG/Pal. Low-dose radiation prevented diabetic cardiomyopathy by improving cardiac function and hypertrophic remodelling attributed to Akt/MDM2/P53-mediated anti-apoptotic and Akt/Nrf2-mediated anti-oxidant pathways simultaneously. © 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  4. Dynamic changes in the proteome of human peripheral blood mononuclear cells with low dose ionizing radiation.

    Science.gov (United States)

    Nishad, S; Ghosh, Anu

    2016-02-01

    Humans are continually exposed to ionizing radiation from natural as well as anthropogenic sources. Though biological effects of high dose radiation exposures have been well accepted, studies on low-to-moderate dose exposures (in the range of 50-500 mGy) have been strongly debated even as researchers continue to search for elusive 'radiation signatures' in humans. Proteins are considered as dynamic functional players that drive cellular responses. However, there is little proteomic information available in context of human exposure to ionizing radiation. In this study, we determined differential expressed proteins in G0 peripheral blood mononuclear cells (PBMCs) from healthy individuals 1h and 4h after 'ex vivo' exposure with two radiation doses (300 mGy and 1 Gy). Twenty-three proteins were found to be significantly altered in irradiated cells when compared to sham irradiated cells with fold change ± 1.5-fold (p ≤ 0.05), with only three proteins showing ≥ 2.5-fold change, either with dose or with time. Mass spectrometry analyses identified redox sensor protein, chloride intracellular channel protein 1 (CLIC-1), the antioxidant protein, peroxiredoxin-6 and the pro-survival molecular chaperone 78 KDa glucose regulated protein (GRP78) among the 23 modulated proteins. The mean coefficient of variation (CV) for the twenty-three radiation responsive protein spots was found to be 33.7% for 300 mGy and 48.3% for 1 Gy. We thus, conclude that the radiation proteomic response of G0 human PBMCs, which are in the resting stage of the cell cycle, involves moderate upregulation of protective mechanisms, with low inter-individual variability. This study will help further our understanding of cellular effects of low dose acute radiation in humans and contribute toward differential biomarker discovery. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Evaluation of occupational and patient radiation doses in orthopedic surgery

    Energy Technology Data Exchange (ETDEWEB)

    Sulieman, A. [Salman bin Abdulaziz University, College of Applied Medical Sciences, Radiology and Medical Imaging Department, P.O. Box 422, Alkharj (Saudi Arabia); Habiballah, B.; Abdelaziz, I. [Sudan Univesity of Science and Technology, College of Medical Radiologic Sciences, P.O. Box 1908, Khartoum (Sudan); Alzimami, K. [King Saud University, College of Applied Medical Sciences, Radiological Sciences Department, P.O. Box 10219, 11433 Riyadh (Saudi Arabia); Osman, H. [Taif University, College of Applied Medical Science, Radiology Department, Taif (Saudi Arabia); Omer, H. [University of Dammam, Faculty of Medicine, Dammam (Saudi Arabia); Sassi, S. A., E-mail: Abdelmoneim_a@yahoo.com [Prince Sultan Medical City, Department of Medical Physics, Riyadh (Saudi Arabia)

    2014-08-15

    Orthopedists are exposed to considerable radiation dose during orthopedic surgeries procedures. The staff is not well trained in radiation protection aspects and its related risks. In Sudan, regular monitoring services are not provided for all staff in radiology or interventional personnel. It is mandatory to measure staff and patient exposure in order to radiology departments. The main objectives of this study are: to measure the radiation dose to patients and staff during (i) Dynamic Hip Screw (Dhs) and (i i) Dynamic Cannula Screw (Dcs); to estimate the risk of the aforementioned procedures and to evaluate entrance surface dose (ESD) and organ dose to specific radiosensitive patients organs. The measurements were performed in Medical Corps Hospital, Sudan. The dose was measured for unprotected organs of staff and patient as well as scattering radiation. Calibrated Thermoluminescence dosimeters (TLD-Gr-200) of lithium fluoride (LiF:Mg, Cu,P) were used for ESD measurements. TLD signal are obtained using automatic TLD Reader model (Plc-3). The mean patients doses were 0.46 mGy and 0.07 for Dhs and Dcs procedures, respectively. The mean staff doses at the thyroid and chest were 4.69 mGy and 1.21 mGy per procedure. The mean radiation dose for staff was higher in Dhs compared to Dcs. This can be attributed to the long fluoroscopic exposures due to the complication of the procedures. Efforts should be made to reduce radiation exposure to orthopedic patients, and operating surgeons especially those with high work load. Staff training and regular monitoring will reduce the radiation dose for both patients and staff. (Author)

  6. Halo Mass Dependence of HI and OVI Absorption: Evidence for Differential Kinematics

    CERN Document Server

    Mathes, Nigel L; Kacprzak, Glenn G; Nielsen, Nikole M; Trujillo-Gomez, Sebastian; Charlton, Jane; Muzahid, Sowgat

    2014-01-01

    We studied a sample of 14 galaxies (0.1 < z < 0.7) using HST/WFPC2 imaging and high-resolution HST/COS or HST/STIS quasar spectroscopy of Lya, Lyb, OVI1031, and OVI1037 absorption. The galaxies, having 10.8 < log(M/M_solar) < 12.2, lie within D = 300 kpc of quasar sightlines, probing out to D/R_vir = 3. When the full range of galaxy virial masses and D/R_vir of the sample are examined, 40% of the HI absorbing clouds can be inferred to be escaping their host halo. The fraction of bound clouds decreases as D/R_vir increases such that the escaping fraction is around 15% for D/R_vir < 1, around 45% for 1 < D/R_vir < 2, and around 90% for 2 < D/R_vir < 3. Adopting the median mass log(M/M_solar) = 11.5 to divide the sample into "higher" and "lower" mass galaxies, we find mass dependency for the hot CGM kinematics. To our survey limits, OVI absorption is found in only 40% of the HI clouds in and around lower mass halos as compared to 85% around higher mass halos. For D/R < 1, lower mass...

  7. Radiative transfer in a clumpy universe: IV. New synthesis models of the cosmic UV/X-ray background

    CERN Document Server

    Haardt, Francesco

    2011-01-01

    We present improved synthesis models of the evolving spectrum of the UV/X-ray diffuse background, updating and extending our previous results. Five new main components are added to our radiative transfer code CUBA: (1) the sawtooth modulation of the background intensity from resonant line absorption in the Lyman series of cosmic hydrogen and helium; (2) the X-ray emission from obscured and unobscured quasars; (3) a piecewise parameterization of the distribution in redshift and column density of intergalactic absorbers that fits recent measurements of the mean free path of 1 ryd photons; (4) an accurate treatment of the photoionization structure of absorbers; and (5) the UV emission from star-forming galaxies at all redshifts. We provide tables of the predicted HI and HeII photoionization and photoheating rates for use, e.g., in cosmological hydrodynamics simulations of the Lya forest, and a new metallicity-dependent calibration to the UV luminosity density-star formation rate density relation. A "minimal cosm...

  8. A High Signal-to-Noise UV Spectrum of NGC 7469 New Support for Reprocessing of Continuum Radiation

    CERN Document Server

    Kriss, G A; Crenshaw, D M; Zheng, W; Kriss, Gerard A.; Peterson, Bradley M.; Zheng, Wei

    2000-01-01

    From 1996 June 10 to 1996 July 29 the International AGN Watch monitored the Seyfert 1 galaxy NGC 7469 using IUE, RXTE, and a network of ground-based observatories. On 1996 June 18, in the midst of this intensive monitoring period, we obtained a high signal-to-noise snapshot of the UV spectrum from 1150-3300 A using the FOS on HST. This spectrum allows us to disentangle the UV continuum more accurately from the broad wings of the emission lines, to identify clean continuum windows free of contaminating emission and absorption, and to deblend line complexes such as Lya+NV, CIV+HeII+OIII], SiIII]+CIII], and MgII+FeII. Using the FOS spectrum as a template, we have fit and extracted line and continuum fluxes from the IUE monitoring data. The cleaner continuum extractions confirm the discovery of time delays between the different UV continuum bands by Wanders et al. Our new measurements show delays increasing with wavelength for continuum bands centered at 1485 A, 174