Science.gov

Sample records for beam lifetime studies

  1. Slow positron beam generator for lifetime studies

    NASA Technical Reports Server (NTRS)

    Singh, Jag J. (Inventor); Eftekhari, Abe (Inventor); St.clair, Terry L. (Inventor)

    1991-01-01

    A slow positron beam generator uses a conductive source residing between two test films. Moderator pieces are placed next to the test film on the opposite side of the conductive source. A voltage potential is applied between the moderator pieces and the conductive source. Incident energetic positrons: (1) are emitted from the conductive source; (2) are passed through test film; and (3) isotropically strike moderator pieces before diffusing out of the moderator pieces as slow positrons, respectively. The slow positrons diffusing out of moderator pieces are attracted to the conductive source which is held at an appropriate potential below the moderator pieces. The slow positrons have to pass through the test films before reaching the conductive source. A voltage is adjusted so that the potential difference between the moderator pieces and the conductive source forces the positrons to stop in the test films. Measurable annihilation radiation is emitted from the test film when positrons annihilate (combine) with electrons in the test film.

  2. A slow positron beam generator for lifetime studies

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Eftekhari, Abe; St.clair, Terry L.

    1989-01-01

    A slow positron beam generator using well-annealed polycrystalline tungsten moderators and a Na-22 positron source was developed. A 250 micro c source, deposited on a 2.54 micron thick aluminized mylar, is sandwiched between two (2.54 cm x 2.54 cm x 0.0127 cm) tungsten pieces. Two (2.54 cm x 2.54 cm x t cm) test polymer films insulate the two tungsten moderator pieces from the aluminized mylar source holder (t=0.00127 to 0.0127). A potential difference of 10 to 100 volts--depending on the test polymer film thickness (t)--is applied between the tungsten pieces and the source foil. Thermalized positrons diffusing out of the moderator pieces are attracted to the source foil held at an appropriate potential below the moderator pieces. These positrons have to pass through the test polymer films before they can reach the source foil. The potential difference between the moderator pieces and the aluminized mylar is so adjusted as to force the positrons to stop in the test polymer films. Thus the new generator becomes an effective source of positrons for assaying thin polymer films for their molecular morphology.

  3. High energy beam lifetime analysis

    SciTech Connect

    Howell, R.H.; Sterne, P.A.; Hartley, J.; Cowan, T.E.

    1997-05-01

    We have developed a positron lifetime defect analysis capability based on a 3 MeV electrostatic accelerator. The high energy beam lifetime spectrometer is operational with a 60 mCi {sup 22}Na source providing a current of 7 10{sup 5} positrons per second. Lifetime data are derived from a thin plastic transmission detector providing an implantation time and a BaF{sub 2} detector to determine the annihilation time. Positron lifetime analysis is performed with a 3 MeV positron beam on thick sample specimens at counting rates in excess of 2000 per second. The instrument is being used for bulk sample analysis and analysis of samples encapsulated in controlled environments for in situ measurements.

  4. The TRIple PLunger for EXotic beams TRIPLEX for excited-state lifetime measurement studies on rare isotopes

    NASA Astrophysics Data System (ADS)

    Iwasaki, H.; Dewald, A.; Braunroth, T.; Fransen, C.; Smalley, D.; Lemasson, A.; Morse, C.; Whitmore, K.; Loelius, C.

    2016-01-01

    A new device, the TRIple PLunger for EXotic beams (TRIPLEX), has been developed for lifetime measurement studies with rare isotope beams. This plunger device holds up to three metal foils in the beam path and facilitates the recoil distance Doppler-shift technique to measure lifetimes of nuclear excited states in the range of 1 ps to 1 ns. The unique design allows independent movement of the target and the second degrader with respect to a fixed first degrader in between, enabling advanced experimental approaches, such as the differential recoil distance method and the double recoil distance method. The design and control of the device are presented in this paper, together with simulated performances of the new applications. As an example of actual experiments, results from the lifetime measurement of the neutron-rich 17C isotope performed at the National Superconducting Cyclotron Laboratory are shown.

  5. 6-D weak-strong beam-beam simulation study of proton lifetime in presence of head-on beam-beam compensation in the RHIC

    SciTech Connect

    Luo, Y.; Fischer, W.

    2010-08-01

    In this note we summarize the calculated particle loss of a proton bunch in the presence of head-on beam-beam compensation in the Relativistic Heavy Ion Collider (RHIC). To compensate the head-on beam-beam effect in the RHIC 250 GeV polarized proton run, we are introducing a DC electron beam with the same transverse profile as the proton beam to collide with the proton beam. Such a device is called an electron lens (e-lens). In this note we first present the optics and beam parameters and the tracking setup. Then we calculate and compare the particle loss of a proton bunch with head-on beam-beam compensation, phase advance of k{pi} between IP8 and the center of the e-lens and second order chromaticity correction. We scanned the proton beam's linear chromaticity, working point and bunch intensity. We also scanned the electron beam's intensity, transverse beam size. The effect of the electron-proton transverse offset in the e-lens was studied. In the study 6-D weak-strong beam-beam interaction model a la Hirata is used for proton collisions at IP6 and IP8. The e-lens is modeled as 8 slices. Each slice is modeled with as drift - (4D beam-beam kick) - drift.

  6. Measurement of Beam Lifetime and Applications for SPEAR3

    SciTech Connect

    Huang, Xiaobiao; Corbett, Jeff; /SLAC

    2011-04-05

    Beam lifetime studies for the SPEAR3 storage ring are presented. The three lifetime components are separated with lifetime measurements under various combinations of beam currents and fill patterns and vertical scraper scans. Touschek lifetime is studied with rf voltage scans and with the horizontal or vertical scrapers inserted. The measurements are explained with calculations based on the calibrated lattice model. Quantum lifetime measurements are performed with reduced longitudinal and horizontal apertures, respectively, from which we deduce the radiation energy loss down to a few keV per revolution and the horizontal beam size.

  7. Lifetime and Tail Simulations for Beam-Beam Effects in PEP-II B Factory

    SciTech Connect

    Shatilov, D.N.; Zholents, A.A.

    1994-12-01

    A fast tracking technique for doing beam tail simulations has been applied to a study of beam-beam effects in the SLAC/LBL/LLNL PEP-II B Factory. In particular, the dependence of beam lifetime and particle density distribution due to vacuum pressure, damping times, machine nonlinearity and parasitic crossings has been analyzed. Effects of accidental orbit separation and dispersion function at the interaction point (IP) have also been considered.

  8. Measurements of aperture and beam lifetime using movable beam scrapers in Indus-2 electron storage ring

    SciTech Connect

    Kumar, Pradeep; Ghodke, A. D.; Karnewar, A. K.; Holikatti, A. C.; Yadav, S.; Puntambekar, T. A.; Singh, G.; Singh, P.

    2013-12-15

    In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.

  9. BEAM LIFETIME AND EMITTANCE GROWTH MEASUREMENTS OF GOLD BEAMS IN RHIC AT STORAGE.

    SciTech Connect

    FISCHER,W.; DREES,A.; BRENNAN,J.M.; CONNOLLY,R.; FLILLER,R.; TEPIKIAN,S.; VAN ZEIJTS,J.

    2001-06-18

    During stores of gold beams, longitudinal and transverse beam sizes were recorded. Longitudinal profiles were obtained with a wall current monitor. Transverse profiles were reconstructed from gold-gold collision rates at various relative transverse beam positions. The total beam lifetime was measured with a beam current transformer, the bunched beam lifetime with the wall current monitor. Diffusion rates in the beam halo were determined from the change in the loss rate when a scraper is retracted. The measurements are used to determine the lifetime limiting effects. Beam growth measurements are compared with computations of beam-growth times from intra-beam scattering.

  10. Beam lifetime and limitations during low-energy RHIC operation

    SciTech Connect

    Fedotov, A.V.; Bai, M.; Blaskiewicz, M.; Fischer, W.; Kayran, D.; Montag, C.; Satogata, T.; Tepikian, S.; Wang, G.

    2011-03-28

    The low-energy physics program at the Relativistic Heavy Ion Collider (RHIC), motivated by a search for the QCD phase transition critical point, requires operation at low energies. At these energies, large nonlinear magnetic field errors and large beam sizes produce low beam lifetimes. A variety of beam dynamics effects such as Intrabeam Scattering (IBS), space charge and beam-beam forces also contribute. All these effects are important to understand beam lifetime limitations in RHIC at low energies. During the low-energy RHIC physics run in May-June 2010 at beam {gamma} = 6.1 and {gamma} = 4.1, gold beam lifetimes were measured for various values of space-charge tune shifts, transverse acceptance limitation by collimators, synchrotron tunes and RF voltage. This paper summarizes our observations and initial findings.

  11. BL3: A Next Generation Beam Neutron Lifetime Experiment

    NASA Astrophysics Data System (ADS)

    Wietfeldt, F. E.; Fomin, N.; Greene, G. L.; Snow, W. M.; Liu, C.-Y.; Crawford, C. B.; Korsch, W.; Plaster, B.; Jones, G. L.; Collett, B.; Dewey, M. S.

    2016-09-01

    BL3 (Beam Lifetime 3) is a proposed next generation neutron lifetime experiment using the beam method. It continues a program, spanning more than three decades, of experiments at the ILL (France) and the NIST Center for Neutron Research that achieved the most precise beam method neutron lifetime measurements to date. A collimated cold neutron beam passes through a quasi-Penning trap where recoil protons from neutron decay are trapped. Periodically the trap is opened and these protons follow a bend in the magnetic field to a silicon detector. The same neutron beam passes through a thin-foil neutron counter that measures the neutron density. The ratio of neutron and proton count rates, along with efficiency factors, gives the neutron lifetime. The main goal of BL3 is to thoroughly investigate and test systematic effects in the beam method in an effort to address the current 4 σ discrepancy between the beam and bottle methods. It will employ a much larger, higher flux neutron beam, a large area position-sensitive proton detector, and an improved magnet design, with a proton trapping rate 100 times higher than past experiments. National Science Foundation, U.S. Dept. of Energy Office of Science.

  12. Progress toward a new beam measurement of the neutron lifetime

    NASA Astrophysics Data System (ADS)

    Hoogerheide, Shannon Fogwell

    2016-09-01

    Neutron beta decay is the simplest example of nuclear beta decay. A precise value of the neutron lifetime is important for consistency tests of the Standard Model and Big Bang Nucleosysnthesis models. The beam neutron lifetime method requires the absolute counting of the decay protons in a neutron beam of precisely known flux. Recent work has resulted in improvements in both the neutron and proton detection systems that should permit a significant reduction in systematic uncertainties. A new measurement of the neutron lifetime using the beam method will be performed at the National Institute of Standards and Technology Center for Neutron Research. The projected uncertainty of this new measurement is 1 s. An overview of the measurement and the technical improvements will be discussed.

  13. Progress toward a new beam measurement of the neutron lifetime

    NASA Astrophysics Data System (ADS)

    Hoogerheide, Shannon Fogwell; BL2 Collaboration

    2017-01-01

    Neutron beta decay is the simplest example of nuclear beta decay. A precise value of the neutron lifetime is important for consistency tests of the Standard Model and Big Bang Nucleosynthesis models. The beam neutron lifetime method requires the absolute counting of the decay protons in a neutron beam of precisely known flux. Recent work has resulted in improvements in both the neutron and proton detection systems that should permit a significant reduction in systematic uncertainties. A new measurement of the neutron lifetime using the beam method is underway at the National Institute of Standards and Technology Center for Neutron Research. The projected uncertainty of this new measurement is 1 s. An overview of the measurement, its current status, and the technical improvements will be discussed.

  14. Electron Beam Lifetime in SPEAR3: Measurement and Simulation

    SciTech Connect

    Corbett, J.; Huang, X.; Lee, M.; Lui, P.; Sayyar-Rodsari, B.; /Pavilon Tech., Austin

    2007-12-19

    In this paper we report on electron beam lifetime measurements as a function of scraper position, RF voltage and bunch fill pattern in SPEAR3. We then outline development of an empirical, macroscopic model using the beam-loss rate equation. By identifying the dependence of loss coefficients on accelerator and beam parameters, a numerically-integrating simulator can be constructed to compute beam decay with time. In a companion paper, the simulator is used to train a parametric, non-linear dynamics model for the system [1].

  15. Neutron lifetime measurement with pulsed beam at JPARC: Overview

    NASA Astrophysics Data System (ADS)

    Mishima, Kenji; Ino, Takashi; Taketani, Kaoru; Yamada, Takahito; Katayama, Ryo; Higashi, Nao; Yokoyama, Harumichi; Sumino, Hirochika; Yamashita, Satoru; Sakakibara, Risa; Sugino, Tomoaki; Kitaguchi, Masaaki; Hirota, Katsuya; Shimizu, Hirohiko M.; Tanaka, Genki; Sumi, Naoyuki; Otono, Hidetoshi; Yoshioka, Tamaki; Kitahara, Ryunosuke; Iwashita, Yoshihisa; Oide, Hideyuki; Shima, Tatsushi; Seki, Yoshichika; NOP Collaboration

    2014-09-01

    The neutron lifetime is an important parameter for a test of the Standard Model of elementary particles, as well for the production of light mass nuclei in big bang nucleosynthesis. There are two principally different approaches to measure the neutron lifetime: In-beam methods and storage of ultracold neutron. At present, there is a discrepancy of 8.4 sec (3.8 sigma) between the two methods. We are performing a new In-beam experiment with an intense pulsed neutron source at J-PARC, which has different systematic uncertainties from the previous experiments. We introduce the overview of the experiment and report present status.

  16. Positron lifetime spectrometer using a DC positron beam

    DOEpatents

    Xu, Jun; Moxom, Jeremy

    2003-10-21

    An entrance grid is positioned in the incident beam path of a DC beam positron lifetime spectrometer. The electrical potential difference between the sample and the entrance grid provides simultaneous acceleration of both the primary positrons and the secondary electrons. The result is a reduction in the time spread induced by the energy distribution of the secondary electrons. In addition, the sample, sample holder, entrance grid, and entrance face of the multichannel plate electron detector assembly are made parallel to each other, and are arranged at a tilt angle to the axis of the positron beam to effectively separate the path of the secondary electrons from the path of the incident positrons.

  17. Bessel beam fluorescence lifetime tomography of live embryos (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Xu, Dongli; Peng, Leilei

    2016-03-01

    Optical tomography allows isotropic 3D imaging of embryos. Scanning-laser optical tomography (SLOT) has superior light collecting efficiency than wide-field optical tomography, making it ideal for fluorescence imaging of live embryos. We previously reported an imaging system that combines SLOT with a novel Fourier-multiplexed fluorescence lifetime imaging (FmFLIM) technique named FmFLIM-SLOT. FmFLIM-SLOT performs multiplexed FLIM-FRET readout of multiple FRET sensors in live embryos. Here we report a recent effort on improving the spatial resolution of the FmFLIM-SLOT system in order to image complex biochemical processes in live embryos at the cellular level. Optical tomography has to compromise between resolution and the depth of view. In SLOT, the commonly-used focused Gaussian beam diverges quickly from the focal plane, making it impossible to achieve high resolution imaging in a large volume specimen. We thus introduce Bessel beam laser-scanning tomography, which illuminates the sample with a spatial-light-modulator-generated Bessel beam that has an extended focal depth. The Bessel beam is scanned across the whole specimen. Fluorescence projection images are acquired at equal angular intervals as the sample rotates. Reconstruction artifacts due to annular-rings of the Bessel beam are removed by a modified 3D filtered back projection algorithm. Furthermore, in combination of Fourier-multiplexing fluorescence lifetime imaging (FmFLIM) method, the Bessel FmFLIM-SLOT system is capable of perform 3D lifetime imaging of live embryos at cellular resolution. The system is applied to in-vivo imaging of transgenic Zebrafish embryos. Results prove that Bessel FmFLIM-SLOT is a promising imaging method in development biology research.

  18. Positron beam lifetime spectroscopy of atomic scale defect distributions in bulk and microscopic volumes

    SciTech Connect

    Howell, R.H.; Cowan, T.E.; Hartley, J.; Sterne, P.; Brown, B.

    1996-05-01

    We are developing a defect analysis capability based on two positron beam lifetime spectrometers: the first is based on a 3 MeV electrostatic accelerator and the second on our high current linac beam. The high energy beam lifetime spectrometer is operational and positron lifetime analysis is performed with a 3 MeV positron beam on thick samples. It is being used for bulk sample analysis and analysis of samples encapsulated in controlled environments for {ital in}{ital situ} measurements. A second, low energy, microscopically focused, pulsed positron beam for defect analysis by positron lifetime spectroscopies is under development at the LLNL high current positron source. This beam will enable defect specific, 3-D maps of defect concentration with sub-micron location resolution and when coupled with first principles calculations of defect specific positron lifetimes it will enable new levels of defect concentration mapping and defect identification.

  19. A code for calculating intrabeam scattering and beam lifetime

    SciTech Connect

    Kim, C.H.

    1997-05-01

    Beam emittances in a circular accelerator with a high beam intensity are strongly affected by the small angle intrabeam Coulomb scattering. In the computer simulation model the authors present here they used three coupled nonlinear differential equations to describe the evolution of the emittances in the transverse and the longitudinal planes. These equations include terms which take into account the intra-beam scattering, adiabatic damping, microwave instabilities, synchrotron damping, and quantum excitations. A code is generated to solve the equations numerically and incorporated into a FORTRAN code library. Circular high intensity physics routines are included in the library such as intrabeam scattering, Touschek scattering, and the bunch lengthening effect of higher harmonic cavities. The code runs presently in the PC environment. Description of the code and some examples are presented.

  20. Minority carrier lifetime in iodine-doped molecular beam epitaxy-grown HgCdTe

    SciTech Connect

    Madni, I.; Umana-Membreno, G. A.; Lei, W.; Gu, R.; Antoszewski, J.; Faraone, L.

    2015-11-02

    The minority carrier lifetime in molecular beam epitaxy grown layers of iodine-doped Hg{sub 1−x}Cd{sub x}Te (x ∼ 0.3) on CdZnTe substrates has been studied. The samples demonstrated extrinsic donor behavior for carrier concentrations in the range from 2 × 10{sup 16} cm{sup −3} to 6 × 10{sup 17} cm{sup −3} without any post-growth annealing. At a temperature of 77 K, the electron mobility was found to vary from 10{sup 4} cm{sup 2}/V s to 7 × 10{sup 3} cm{sup 2}/V s and minority carrier lifetime from 1.6 μs to 790 ns, respectively, as the carrier concentration was increased from 2 × 10{sup 16} cm{sup −3} to 6 × 10{sup 17} cm{sup −3}. The diffusion of iodine is much lower than that of indium and hence a better alternative in heterostructures such as nBn devices. The influence of carrier concentration and temperature on the minority carrier lifetime was studied in order to characterize the carrier recombination mechanisms. Measured lifetimes were also analyzed and compared with the theoretical models of the various recombination processes occurring in these materials, indicating that Auger-1 recombination was predominant at higher doping levels. An increase in deep-level generation-recombination centers was observed with increasing doping level, which suggests that the increase in deep-level trap density is associated with the incorporation of higher concentrations of iodine into the HgCdTe.

  1. Lifetime measurements in an electrostatic ion beam trap using image charge monitoring

    SciTech Connect

    Rahinov, Igor; Toker, Yoni; Heber, Oded; Rappaport, Michael; Zajfman, Daniel; Strasser, Daniel; Schwalm, Dirk

    2012-03-15

    A technique for mass-selective lifetime measurements of keV ions in a linear electrostatic ion beam trap is presented. The technique is based on bunching the ions using a weak RF potential and non-destructive ion detection by a pick-up electrode. This method has no mass-limitation, possesses the advantage of inherent mass-selectivity, and offers a possibility of measuring simultaneously the lifetimes of different ion species with no need for prior mass-selection.

  2. RHIC PROTON BEAM LIFETIME INCREASE WITH 10- AND 12-POLE CORRECTORS

    SciTech Connect

    Fischer, W.

    2010-05-23

    The RHIC beam lifetime in polarized proton operation is dominated by the beam-beam effect, parameter modulations, and nonlinear magnet errors in the interaction region magnets. Sextupole and skew sextupole errors have been corrected deterministically for a number of years based on tune shift measurements with orbit bumps in the triplets. During the most recent polarized proton run 10- and 12- pole correctors were set through an iterative procedure, and used for the first time operationally in one of the beams. We report on the procedure to set these high-order multipole correctors and estimate their effect on the integrated luminosity.

  3. Plunger lifetime measurements after Coulomb excitation at intermediate beam energies

    SciTech Connect

    Dewald, A.; Hackstein, M.; Rother, W.; Jolie, J.; Melon, B.; Pissulla, T.; Shimbara, Y.; Starosta, K.; Adrich, P.; Amthor, A. M.; Baumann, T.; Bazin, D.; Bowen, M.; Chester, A.; Dunomes, A.; Gade, A.; Galaviz, D.; Glasmacher, T.; Ginter, T.; Hausmann, M.

    2009-01-28

    Absolute transition probabilities of the first 2{sup +} state in {sup 110,114}Pd were remeasured using the recoil distance Doppler shift technique following projectile Coulomb excitation at intermediate beam energies for the first time. The {sup 110}Pd experiment served to check the novel technique as well as the method used for the data analysis which is based on the examination of {gamma}-ray lineshapes. Whereas the measured B(E2) value for {sup 110}Pd agrees very well with the literature, the value obtained for {sup 114}Pd differs considerably. The data is also used to test a novel concept, called the valence proton symmetry, which allows one to extrapolate nuclear properties to very neutron rich nuclei.

  4. Measuring the free neutron lifetime to <= 0.3s via the beam method

    NASA Astrophysics Data System (ADS)

    Fomin, Nadia; Mulholland, Jonathan

    2015-04-01

    Neutron beta decay is an archetype for all semi-leptonic charged-current weak processes. A precise value for the neutron lifetime is required for consistency tests of the Standard Model and is needed to predict the primordial 4 He abundance from the theory of Big Bang Nucleosynthesis. An effort has begun for an in-beam measurement of the neutron lifetime with an projected <=0.3s uncertainty. This effort is part of a phased campaign of neutron lifetime measurements based at the NIST Center for Neutron Research, using the Sussex-ILL-NIST technique. Recent advances in neutron fluence measurement techniques as well as new large area silicon detector technology address the two largest sources of uncertainty of in-beam measurements, paving the way for a new measurement. The experimental design and projected uncertainties for the 0.3s measurement will be discussed. This work is supported by the DOE office of Science, NIST and NSF.

  5. CONSTRAINTS ON QUASAR LIFETIMES AND BEAMING FROM THE He II Ly{alpha} FOREST

    SciTech Connect

    Furlanetto, Steven R.; Lidz, Adam

    2011-07-10

    We show that comparisons of He II Ly{alpha} forest lines of sight to nearby quasar populations can strongly constrain the lifetimes and emission geometry of quasars. By comparing the He II and H I Ly{alpha} forests along a particular line of sight, one can trace fluctuations in the hardness of the radiation field (which are driven by fluctuations in the He II ionization rate). Because this high-energy background is highly variable-thanks to the rarity of the bright quasars that dominate it and the relatively short attenuation lengths of these photons-it is straightforward to associate features in the radiation field with their source quasars. Here we quantify how finite lifetimes and beamed emission geometries affect these expectations. Finite lifetimes induce a time delay that displaces the observed radiation peak relative to the quasar. For beamed emission, geometry dictates that sources invisible to the observer can still create a peak in the radiation field. We show that both these models produce substantial populations of 'bare' peaks (without an associated quasar) for reasonable parameter values (lifetimes {approx}10{sup 6}-10{sup 8} yr and beaming angles {approx}< 90 deg.). A comparison to existing quasar surveys along two He II Ly{alpha} forest lines of sight rules out isotropic emission and infinite lifetime at high confidence; they can be accommodated either by moderate beaming or lifetimes {approx}10{sup 7}-10{sup 8} yr. We also show that the distribution of radial displacements between peaks and their quasars can unambiguously distinguish these two models, although larger statistical samples are needed.

  6. Constraints on Quasar Lifetimes and Beaming from the He II Lyα Forest

    NASA Astrophysics Data System (ADS)

    Furlanetto, Steven R.; Lidz, Adam

    2011-07-01

    We show that comparisons of He II Lyα forest lines of sight to nearby quasar populations can strongly constrain the lifetimes and emission geometry of quasars. By comparing the He II and H I Lyα forests along a particular line of sight, one can trace fluctuations in the hardness of the radiation field (which are driven by fluctuations in the He II ionization rate). Because this high-energy background is highly variable—thanks to the rarity of the bright quasars that dominate it and the relatively short attenuation lengths of these photons—it is straightforward to associate features in the radiation field with their source quasars. Here we quantify how finite lifetimes and beamed emission geometries affect these expectations. Finite lifetimes induce a time delay that displaces the observed radiation peak relative to the quasar. For beamed emission, geometry dictates that sources invisible to the observer can still create a peak in the radiation field. We show that both these models produce substantial populations of "bare" peaks (without an associated quasar) for reasonable parameter values (lifetimes ~106-108 yr and beaming angles <~ 90°). A comparison to existing quasar surveys along two He II Lyα forest lines of sight rules out isotropic emission and infinite lifetime at high confidence; they can be accommodated either by moderate beaming or lifetimes ~107-108 yr. We also show that the distribution of radial displacements between peaks and their quasars can unambiguously distinguish these two models, although larger statistical samples are needed.

  7. Assessment of the lifetime of the beam window of MEGAPIE target liquid metal container

    NASA Astrophysics Data System (ADS)

    Dai, Y.; Henry, J.; Auger, T.; Vogt, J.-B.; Almazouzi, A.; Glasbrenner, H.; Groeschel, F.

    2006-09-01

    The lifetime of the beam window of the T91 liquid Pb-Bi container in the MEGAPIE target is discussed based on the present knowledge of lead bismuth eutectic (LBE) corrosion, embrittlement and radiation effects in relevant conditions. In the MEGAPIE target, since the high hydrogen production will likely reduce the oxygen content to a low level, LBE corrosion may reduce the wall thickness up to 2%. In addition, the corrosion induced grain boundary dissolution will promote LBE embrittlement on the T91 steel in the beam window. The DBTT data and fracture toughness values of T91 specimens tested in contact with LBE suggest a lower bound of the lifetime of the T91 beam window to be limited to a dose of 6 dpa, corresponding to 2.4 Ah proton charge to be received by the target in about 20 weeks in the normal operation condition.

  8. Experimental Studies of Compensation of Beam-Beam Effects with Tevatron Electron Lenses

    SciTech Connect

    Shiltsev, V.; Alexahin, Yu.; Bishofberger, Kip; Kamerdzhiev, V.; Parkhomchuk, V.; Reva, V.; Solyak, N.; Wildman, D.; Zhang, X.-L.; Zimmermann, F.; /Fermilab /Los Alamos /Novosibirsk, IYF /CERN

    2008-02-01

    Applying the space-charge forces of a low-energy electron beam can lead to a significant improvement of the beam-particle lifetime limit arising from the beam-beam interaction in a high-energy collider [1]. In this article we present the results of various beam experiments with 'electron lenses', novel instruments developed for the beam-beam compensation at the Tevatron, which collides 980-GeV proton and antiproton beams. We study the dependencies of the particle betatron tunes on the electron beam current, energy and position; we explore the effects of electron-beam imperfections and noises; and we quantify the improvements of the high-energy beam intensity and the collider luminosity lifetime obtained by the action of the Tevatron Electron Lenses.

  9. Engineering the Activity and Lifetime of Heterogeneous Catalysts for Carbon Nanotube Growth via Substrate Ion Beam Bombardment (Postprint)

    DTIC Science & Technology

    2014-07-31

    AFRL-RX-WP-JA-2014-0159 ENGINEERING THE ACTIVITY AND LIFETIME OF HETEROGENEOUS CATALYSTS FOR CARBON NANOTUBE GROWTH VIA SUBSTRATE ION BEAM...July 2014 4. TITLE AND SUBTITLE ENGINEERING THE ACTIVITY AND LIFETIME OF HETEROGENEOUS CATALYSTS FOR CARBON NANOTUBE GROWTH VIA SUBSTRATE ION BEAM... heterogeneous catalyst, catalyst support, ion beam bombardment 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18. NUMBER OF PAGES 11

  10. Neutron lifetime measurement with pulsed beam at J- PARC: TPC and DAQ

    NASA Astrophysics Data System (ADS)

    Yamada, Takahito; Katayama, Ryo; Higashi, Nao; Yokoyama, Harumichi; Sumino, Hirochika; Yamashita, Satoru; Sakakibara, Risa; Sugino, Tomoaki; Kitaguchi, Masaaki; Hirota, Katsuya; Shimizu, Hirohiko M.; Tanaka, Genki; Sumi, Naoyukio; Otono, Hidetoshi; Yoshioka, Tamaki; Kitahara, Ryunosuke; Iwashita, Yoshihisa; Oide, Hideyuki; Shima, Tatsushi; Seki, Yoshichika; Mishima, Kenji; Taketani, Kaoru; Ino, Takashi; NOP Collaboration

    2014-09-01

    The neutron lifetime is an important parameter for Big Bang nucleosynthesis (BBN). The best neutron lifetime measurements have uncertainties at the 0.1% level; however, they differ by 3.8 sigma. In order to resolve this discrepancy, we plan to measure the neutron lifetime using a method originally developed by Kossakowski et al. which is different from the other 0.1% accuracy experiments. In our method, which uses a pulsed cold neutron beam at J-PARC, the electrons from the beta decay of the neutron are detected with a time projection chamber (TPC). A small amount of 3He is added to the gas mixture in order to simultaneously measure the neutron flux. We report on the recent upgrade of the TPC and the Data Acquisition System which were used to take data during the period of February-June 2014.

  11. Equilibrium Beam Distribution and Quantum Lifetime in the Presence of a Single Nonlinear Resonance

    SciTech Connect

    Chao, A

    2003-12-09

    In the proximity of a nonlinear resonance {nu} {approx} m/n, n , the beam distribution in a storage ring is distorted depending on how close by is the resonance and how strong is the resonance strength. In the 1-dimensional case, it is well known that the particle motion near the resonance can be described in a smooth approximation by a Hamiltonian of the form ({nu} - m/n) J + D{sub {nu}}(J) + f{sub 1}({phi}, J), where ({phi}, J) are the phase space angle and action variables, D{sub {nu}} is the detuning function, and f{sub 1} is an oscillating resonance term. In a proton storage ring, the equilibrium beam distribution is readily solved to be any function exclusively of the Hamiltonian. For an electron beam, this is not true and the equilibrium distribution is more complicated. This paper solves the Fokker-Planck equation near a single resonance for an electron beam in a storage ring. The result is then applied to obtain the quantum lifetime of an electron beam in the presence of this resonance. Resonances due to multipole fields and due to the beam-beam force are considered as examples.

  12. Neutron lifetime measurement with pulsed beam at J-PARC:Incident Beam Flux

    NASA Astrophysics Data System (ADS)

    Sakakibara, Risa; Shimizu, Hirohiko M.; Kitaguchi, Masaaki; Hirota, Katsuya; Sugino, Tomoaki; Yamashita, Satoru; Katayama, Ryo; Yamada, Takahito; Higashi, Nao; Yokoyama, Harumichi; Sumino, Hirochika; Yoshioka, Tamaki; Otono, Hidetoshi; Tanaka, Genki; Sumi, Naoyuki; Iwashita, Yoshihisa; Kitahara, Ryunosuke; Oide, Hideyuki; Shima, Tatsushi; Ino, Takashi; Mishima, Kenji; Taketani, Kaoru; Seki, Yoshichika; NOP Collaboration

    2014-09-01

    The neutron lifetime is one of the important parameters in the estimation of the abundance of the light elements in the early universe through the Big Bang Nucleosynthesis (BBN). The accuracy of 0.1% is desired in the neutron lifetime to quantitatively discuss the BBN in combination with the observation of the anisotropy of the cosmic microwave. We have started a lifetime measurement with pulsed neutrons at J-PARC/BL05. To measure the lifetime, we detect the decay electrons from the bunched neutrons and the incident neutron flux in the TPC at the same time. By diluting a small amount of 3He gas into the TPC, the incident flux is estimated by counting protons via 3He(n,p)3H reactions. The accuracy of the selection of 3He(n,p)3H events and the influence of the contamination of nitrogen gas are the major systematic errors. In this paper, the estimation of the systematic error in the incident flux is reported.

  13. A Satellite Mortality Study to Support Space Systems Lifetime Prediction

    NASA Technical Reports Server (NTRS)

    Fox, George; Salazar, Ronald; Habib-Agahi, Hamid; Dubos, Gregory

    2013-01-01

    Estimating the operational lifetime of satellites and spacecraft is a complex process. Operational lifetime can differ from mission design lifetime for a variety of reasons. Unexpected mortality can occur due to human errors in design and fabrication, to human errors in launch and operations, to random anomalies of hardware and software or even satellite function degradation or technology change, leading to unrealized economic or mission return. This study focuses on data collection of public information using, for the first time, a large, publically available dataset, and preliminary analysis of satellite lifetimes, both operational lifetime and design lifetime. The objective of this study is the illustration of the relationship of design life to actual lifetime for some representative classes of satellites and spacecraft. First, a Weibull and Exponential lifetime analysis comparison is performed on the ratio of mission operating lifetime to design life, accounting for terminated and ongoing missions. Next a Kaplan-Meier survivor function, standard practice for clinical trials analysis, is estimated from operating lifetime. Bootstrap resampling is used to provide uncertainty estimates of selected survival probabilities. This study highlights the need for more detailed databases and engineering reliability models of satellite lifetime that include satellite systems and subsystems, operations procedures and environmental characteristics to support the design of complex, multi-generation, long-lived space systems in Earth orbit.

  14. A Satellite Mortality Study to Support Space Systems Lifetime Prediction

    NASA Technical Reports Server (NTRS)

    Fox, George; Salazar, Ronald; Habib-Agahi, Hamid; Dubos, Gregory

    2013-01-01

    Estimating the operational lifetime of satellites and spacecraft is a complex process. Operational lifetime can differ from mission design lifetime for a variety of reasons. Unexpected mortality can occur due to human errors in design and fabrication, to human errors in launch and operations, to random anomalies of hardware and software or even satellite function degradation or technology change, leading to unrealized economic or mission return. This study focuses on data collection of public information using, for the first time, a large, publically available dataset, and preliminary analysis of satellite lifetimes, both operational lifetime and design lifetime. The objective of this study is the illustration of the relationship of design life to actual lifetime for some representative classes of satellites and spacecraft. First, a Weibull and Exponential lifetime analysis comparison is performed on the ratio of mission operating lifetime to design life, accounting for terminated and ongoing missions. Next a Kaplan-Meier survivor function, standard practice for clinical trials analysis, is estimated from operating lifetime. Bootstrap resampling is used to provide uncertainty estimates of selected survival probabilities. This study highlights the need for more detailed databases and engineering reliability models of satellite lifetime that include satellite systems and subsystems, operations procedures and environmental characteristics to support the design of complex, multi-generation, long-lived space systems in Earth orbit.

  15. A satellite mortality study to support space systems lifetime prediction

    NASA Astrophysics Data System (ADS)

    Fox, George; Salazar, Ronald; Habib-Agahi, Hamid; Dubos, Gregory F.

    Estimating the operational lifetime of satellites and spacecraft is a complex process. Operational lifetime can differ from mission design lifetime for a variety of reasons. Unexpected mortality can occur due to human errors in design and fabrication, to human errors in launch and operations, to random anomalies of hardware and software or even satellite function degradation or technology change, leading to unrealized economic or mission return. This study focuses on data collection of public information using, for the first time, a large, publically available dataset, and preliminary analysis of satellite lifetimes, both operational lifetime and design lifetime. The objective of this study is the illustration of the relationship of design life to actual lifetime for some representative classes of satellites and spacecraft. First, a Weibull and Exponential lifetime analysis comparison is performed on the ratio of mission operating lifetime to design life, accounting for terminated and ongoing missions. Next a Kaplan-Meier survivor function, standard practice for clinical trials analysis, is estimated from operating lifetime. Bootstrap resampling is used to provide uncertainty estimates of selected survival probabilities. This study highlights the need for more detailed databases and engineering reliability models of satellite lifetime that include satellite systems and subsystems, operations procedures and environmental characteristics to support the design of complex, multi-generation, long-lived space systems in Earth orbit.

  16. USING A 100 KV DC LOAD LOCK PHOTOGUN TO MEASURE PHOTOCATHODE LIFETIME OF HIGH POLARIZATION STRAINED SUPERLATTICE GAAS/GAASP AT BEAM INTENSITY >1 MILLIAMP

    SciTech Connect

    Joseph Grames; Benard Poelker; Philip Adderley; Joshua Brittian; James Clark; John Hansknecht; Danny Machie; Marcy Stutzman; Kenneth Surles-law; Riad Suleiman

    2007-07-02

    A new GaAs DC high voltage load lock photogun has been constructed at Jefferson Laboratory (JLab), with improved vacuum and photocathode preparation capabilities. As reported previously, this gun was used to study photocathode lifetime with bulk GaAs at DC beam currents between 1 and 10 mA. In this submission, lifetime measurements were performed using high polarization strained-superlattice GaAs photocathode material at beam currents up to 1 mA, with near bandgap light from a fiber based drive laser having picosecond optical pulses and RF time structure.

  17. Feasibility study for long lifetime helium dewar

    NASA Technical Reports Server (NTRS)

    Parmley, R. T.

    1981-01-01

    A feasible concept for a launchable three year lifetime helium dewar was investigted. Current helium dewar designs were examined to see where the largest potential reductions in parasitic heat loads can be made. The study was also devoted to examining support concepts. The support concept chosen, a passive orbital disconnect strut (PODS), has an orbital support conductance that is lower by more than an order of magnitude over current tension band supports. This lower support conductance cuts the total dewar weight in half for the same three year life time requirements. Effort was also concentrated on efficient wire feed through designs and vapor cooling of the multilayer insulation, supports, wire feed throughs and plumbing penetrations. A single stage helium dewar vs. dual stage dewars with a guard cryogen of nitrogen or neon was examined. The single stage dewar concept was selected. Different support concepts were analyzed from which the PODS support concepts was chosen. A preliminary design of the dewar was thermally and structurally analyzed and laid out including system weights, thermal performance and performance sensitivities.

  18. Beam-laser lifetime measurements for some selected levels in singly ionized thulium

    NASA Astrophysics Data System (ADS)

    Rieger, Georg; McCurdy, Michelle M.; Pinnington, Eric H.

    1999-11-01

    The lifetimes of 16 levels in Tm II have been measured using the fast-beam-laser technique to resolve the disagreement between time-resolved laser-induced fluorescence measurements recently published by Anderson, Den Hartog, and Lawler [J. Opt. Soc. Am. B 13, 2382 (1996)] and a new relativistic Hartree-Fock calculation by Quinet, Palmeri, and Biémont [J. Quant. Spectrosc. Radiat. Transf. 62, 625 (1999)]. In all cases except one, our results support the previous measurement, but with a higher precision.

  19. Development of time projection chamber for precise neutron lifetime measurement using pulsed cold neutron beams

    NASA Astrophysics Data System (ADS)

    Arimoto, Y.; Higashi, N.; Igarashi, Y.; Iwashita, Y.; Ino, T.; Katayama, R.; Kitaguchi, M.; Kitahara, R.; Matsumura, H.; Mishima, K.; Nagakura, N.; Oide, H.; Otono, H.; Sakakibara, R.; Shima, T.; Shimizu, H. M.; Sugino, T.; Sumi, N.; Sumino, H.; Taketani, K.; Tanaka, G.; Tanaka, M.; Tauchi, K.; Toyoda, A.; Tomita, T.; Yamada, T.; Yamashita, S.; Yokoyama, H.; Yoshioka, T.

    2015-11-01

    A new time projection chamber (TPC) was developed for neutron lifetime measurement using a pulsed cold neutron spallation source at the Japan Proton Accelerator Research Complex (J-PARC). Managing considerable background events from natural sources and the beam radioactivity is a challenging aspect of this measurement. To overcome this problem, the developed TPC has unprecedented features such as the use of polyether-ether-ketone plates in the support structure and internal surfaces covered with 6Li-enriched tiles to absorb outlier neutrons. In this paper, the design and performance of the new TPC are reported in detail.

  20. Enhanced Plasma Lifetime of Air Plasmas Generated by Electron Beam Excitation

    NASA Astrophysics Data System (ADS)

    Vidmar, Robert; Stalder, Kenneth

    2002-10-01

    A kinetic model with an improved set of reaction rate coefficients for air constituents will be discussed. The model includes rates that vary with E/N for electron temperature, momentum transfer, three body attachment, singlet-delta formation, electron detachment from O2-, and ionization of O2. The electric field is assumed uniform and sustained either by external electrodes or return currents generated in an electron beam. Calculations show the plasma lifetime increases as E/N increases by reducing attachment, increasing detachment, and increasing ionization. Electric-field-free plasma lifetimes of 10-20 ns for air at sea level (depending on initial electron density) can be increased by a factor of almost 5 with an E/N of about 2 x 10-16 volt cm^2. The plasma lifetime at altitudes of 30,000 feet corresponds to 60-100 ns without electric field and increases by a factor of 5-20 with an E/N of 5 x 10-17 volt cm^2. The power to maintain these E/N values and to sustain a given level of plasma density will be discussed. This research is sponsored by the Air Force Research Laboratory, under agreement number F49620-01-1-0414.

  1. Ion Beam Propulsion Study

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Ion Beam Propulsion Study was a joint high-level study between the Applied Physics Laboratory operated by NASA and ASRC Aerospace at Kennedy Space Center, Florida, and Berkeley Scientific, Berkeley, California. The results were promising and suggested that work should continue if future funding becomes available. The application of ion thrusters for spacecraft propulsion is limited to quite modest ion sources with similarly modest ion beam parameters because of the mass penalty associated with the ion source and its power supply system. Also, the ion source technology has not been able to provide very high-power ion beams. Small ion beam propulsion systems were used with considerable success. Ion propulsion systems brought into practice use an onboard ion source to form an energetic ion beam, typically Xe+ ions, as the propellant. Such systems were used for steering and correction of telecommunication satellites and as the main thruster for the Deep Space 1 demonstration mission. In recent years, "giant" ion sources were developed for the controlled-fusion research effort worldwide, with beam parameters many orders of magnitude greater than the tiny ones of conventional space thruster application. The advent of such huge ion beam sources and the need for advanced propulsion systems for exploration of the solar system suggest a fresh look at ion beam propulsion, now with the giant fusion sources in mind.

  2. Carrier Lifetimes of Iodine-Doped CdMgTe/CdSeTe Double Heterostructures Grown by Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Sohal, S.; Edirisooriya, M.; Ogedengbe, O. S.; Petersen, J. E.; Swartz, C. H.; LeBlanc, E. G.; Myers, T. H.; Li, J. V.; Holtz, M.

    2017-09-01

    Iodine-doped CdMgTe/CdSeTe double heterostructures (DHs) have been grown by molecular beam epitaxy and studied using time-resolved photoluminescence (PL), focusing on absorber layer thickness of 2 μm. The n-type free carrier concentration was varied to ˜7 × 1015 cm-3, 8.4 × 1016 cm-3, and 8.4 × 1017 cm-3 using iodine as dopant in DHs. Optical injection at 1 × 1010 photons/pulse/cm2 to 3 × 1011 photons/pulse/cm2, corresponding to initial injection of photocarriers up to ˜8 × 1015 cm-3, was applied to examine the effects of excess carrier concentration on the PL lifetimes. Iodine-doped DHs exhibited an initial rapid decay followed by a slower decay at free carrier concentration of 7 × 1015 cm-3 and 8.4 × 1016 cm-3. The optical injection dependence of the carrier lifetimes for DHs was interpreted based on the Shockley-Read-Hall model. The observed decrease in lifetime with increasing n is consistent with growing importance of radiative recombination.

  3. Fluorescence Lifetime Study of Cyclodextrin Complexes of Substituted Naphthalenes.

    DTIC Science & Technology

    1987-08-15

    k Dft3 462 FLUORESCENCE LIFETIME STUDY OF CYCLODEXTRIN COMPLEXE 1/1 I ADRIO OF SUSTITUTED NAPHTNALENES(U) EMORY UNIV ATLANTA GA I DEPT OF CHEMISTRY G...PROJECT TASK WORK UNIT ELEMENT NO. NO. NO. ACCESSION NO. NR 051-841 11. TITLE (Include Security ClaSSafication) Fluorescence Lifetime Study of Cyclodextrin ...measurements cyclodextrins spectroscopic techniques 19. TRACT (Continue on revere if necsary and identify by block number

  4. Lifetime Measurements of High Polarization Strained-Superlattice Gallium Arsenide at Beam Current > 1 Milliamp using a New 100kV Load Lock Photogun

    SciTech Connect

    J. M. Grames; P. A. Adderley; J. Brittian; J. Clark; J. Hansknecht; D. Machie; M. Poelker; M. L. Stutzman; R. Suleiman; K. E. L. Surles-Law

    2007-08-01

    A new 100 kV GaAs DC Load Lock Photogun has been constructed at Jefferson Laboratory, with improvements for photocathode preparation and for operation in a high voltage, ultra-high vacuum environment. Although difficult to gauge directly, we believe that the new gun design has better vacuum conditions compared to the previous gun design, as evidenced by longer photocathode lifetime, that is, the amount of charge extracted before the quantum efficiency of the photocathode drops by 1/e of the initial value via the ion back-bombardment mechanism. Photocathode lifetime measurements at DC beam intensity of up to 10 mA have been performed to benchmark operation of the new gun and for fundamental studies of the use of GaAs photocathodes at high average current*. These measurements demonstrate photocathode lifetime longer than one million Coulombs per square centimeter at a beam intensity higher than 1 mA. The photogun has been reconfigured with a high polarization strained superlattice photocathode (GaAs/GaAsP) and a mode-locked Ti:Sapphire laser operating near band-gap. Photocathode lifetime measurements at beam intensity greater than 1 mA are measured and presented for comparison.

  5. Degradation of electron-irradiated polyethylene studied by positron annihilation lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Onodera, K.; Oka, T.; Kino, Y.; Sekine, T.

    2017-01-01

    Degradation of electron beam irradiated high-density polyethylene was studied by positron annihilation lifetime spectroscopy (PALS), micro-FT-IR, and gel fraction measurements. The obtained results indicated that ortho-positronium intensity is influenced not only by the irradiation but also the post oxidation, which illustrates that PALS may be a promising tool to monitor/evaluate the degradation of polyethylene induced by irradiation and long-term storage.

  6. Scalable focused ion beam creation of nearly lifetime-limited single quantum emitters in diamond nanostructures

    PubMed Central

    Schröder, Tim; Trusheim, Matthew E.; Walsh, Michael; Li, Luozhou; Zheng, Jiabao; Schukraft, Marco; Sipahigil, Alp; Evans, Ruffin E.; Sukachev, Denis D.; Nguyen, Christian T.; Pacheco, Jose L.; Camacho, Ryan M.; Bielejec, Edward S.; Lukin, Mikhail D.; Englund, Dirk

    2017-01-01

    The controlled creation of defect centre—nanocavity systems is one of the outstanding challenges for efficiently interfacing spin quantum memories with photons for photon-based entanglement operations in a quantum network. Here we demonstrate direct, maskless creation of atom-like single silicon vacancy (SiV) centres in diamond nanostructures via focused ion beam implantation with ∼32 nm lateral precision and <50 nm positioning accuracy relative to a nanocavity. We determine the Si+ ion to SiV centre conversion yield to be ∼2.5% and observe a 10-fold conversion yield increase by additional electron irradiation. Low-temperature spectroscopy reveals inhomogeneously broadened ensemble emission linewidths of ∼51 GHz and close to lifetime-limited single-emitter transition linewidths down to 126±13 MHz corresponding to ∼1.4 times the natural linewidth. This method for the targeted generation of nearly transform-limited quantum emitters should facilitate the development of scalable solid-state quantum information processors. PMID:28548097

  7. Minority Carrier Lifetime Studies of Narrow Bandgap Antimonide Superlattices

    NASA Technical Reports Server (NTRS)

    Hoglund, Linda; Ting, David Z.; Khoshakhlagh, Arezou; Soibel, Alexander; Hill, Cory J.; Fisher, Anita; Keo, Sam; Gunapala, Sarath D.

    2014-01-01

    In this study optical modulation response and photoluminescence spectroscopy were used to study mid-wave Ga-free InAs/InAsSb superlattices. The minority carrier lifetimes in the different samples varied from 480 ns to 4700 ns, partly due to different background doping concentrations. It was shown that the photoluminescence intensity can be used as a fast non-destructive tool to predict the material quality. It was also demonstrated that it is crucial to use a low excitation power in the photoluminescence measurements in order to get a good correlation between the photoluminescence intensity and the minority carrier lifetime.

  8. Minority Carrier Lifetime Studies of Narrow Bandgap Antimonide Superlattices

    NASA Technical Reports Server (NTRS)

    Hoglund, Linda; Ting, David Z.; Khoshakhlagh, Arezou; Soibel, Alexander; Hill, Cory J.; Fisher, Anita; Keo, Sam; Gunapala, Sarath D.

    2014-01-01

    In this study optical modulation response and photoluminescence spectroscopy were used to study mid-wave Ga-free InAs/InAsSb superlattices. The minority carrier lifetimes in the different samples varied from 480 ns to 4700 ns, partly due to different background doping concentrations. It was shown that the photoluminescence intensity can be used as a fast non-destructive tool to predict the material quality. It was also demonstrated that it is crucial to use a low excitation power in the photoluminescence measurements in order to get a good correlation between the photoluminescence intensity and the minority carrier lifetime.

  9. Construction of a surface positronium lifetime spectroscopy apparatus with a spin-polarized low energy positron beam

    NASA Astrophysics Data System (ADS)

    Maekawa, M.; Wada, K.; Miyashita, A.; Kawasuso, A.

    2017-01-01

    We have developed a surface positronium (Ps) lifetime spectrometer. A spin-polarized slow positron beam is generated by a sodium-22 source and a solid krypton moderator and transported to the sample chamber by electrostatic lenses. The incident energy is adjusted by a retarding potential using a deceleration tube. For the lifetime measurement, the start signal is obtained from a secondary-electron detector installed in front of the sample. The stop signal is detected by a scintillation detector for annihilation gamma rays. As a performance test, Ps lifetime measurements were carried out and clear decay curves derived from ortho-Ps self-annihilation were successfully observed. This system might be used for the estimation of the spin polarization at the surface of ferromagnetic materials.

  10. Results of head-on beam-beam compensation studies at the Tevatron

    SciTech Connect

    Valishev, A.; Stancari, G.; /Fermilab

    2011-03-01

    At the Tevatron collider, we studied the feasibility of suppressing the antiproton head-on beam-beamtune spread using a magnetically confined 5-keV electron beam with Gaussian transverse profile overlapping with the circulating beam. When electron cooling of antiprotons is applied in regular Tevatron operations, the head-on beam-beam effect on antiprotons is small. Therefore, we first focused on the operational aspects, such as beam alignment and stability, and on fundamental observations of tune shifts, tune spreads, lifetimes, and emittances. We also attempted two special collider stores with only 3 proton bunches colliding with 3 antiproton bunches, to suppress long-range forces and enhance head-on effects. We present here the results of this study and a comparison between numerical simulations and observations, in view of the planned application of this compensation concept to RHIC.

  11. Autofluorescence lifetime imaging during transoral robotic surgery: a clinical validation study of tumor detection (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Lagarto, João. L.; Phipps, Jennifer E.; Unger, Jakob; Faller, Leta M.; Gorpas, Dimitris; Ma, Dinglong M.; Bec, Julien; Moore, Michael G.; Bewley, Arnaud F.; Yankelevich, Diego R.; Sorger, Jonathan M.; Farwell, Gregory D.; Marcu, Laura

    2017-02-01

    Autofluorescence lifetime spectroscopy is a promising non-invasive label-free tool for characterization of biological tissues and shows potential to report structural and biochemical alterations in tissue owing to pathological transformations. In particular, when combined with fiber-optic based instruments, autofluorescence lifetime measurements can enhance intraoperative diagnosis and provide guidance in surgical procedures. We investigate the potential of a fiber-optic based multi-spectral time-resolved fluorescence spectroscopy instrument to characterize the autofluorescence fingerprint associated with histologic, morphologic and metabolic changes in tissue that can provide real-time contrast between healthy and tumor regions in vivo and guide clinicians during resection of diseased areas during transoral robotic surgery. To provide immediate feedback to the surgeons, we employ tracking of an aiming beam that co-registers our point measurements with the robot camera images and allows visualization of the surgical area augmented with autofluorescence lifetime data in the surgeon's console in real-time. For each patient, autofluorescence lifetime measurements were acquired from normal, diseased and surgically altered tissue, both in vivo (pre- and post-resection) and ex vivo. Initial results indicate tumor and normal regions can be distinguished based on changes in lifetime parameters measured in vivo, when the tumor is located superficially. In particular, results show that autofluorescence lifetime of tumor is shorter than that of normal tissue (p < 0.05, n = 3). If clinical diagnostic efficacy is demonstrated throughout this on-going study, we believe that this method has the potential to become a valuable tool for real-time intraoperative diagnosis and guidance during transoral robot assisted cancer removal interventions.

  12. Lifetime statistics of quantum chaos studied by a multiscale analysis

    SciTech Connect

    Di Falco, A.; Krauss, T. F.; Fratalocchi, A.

    2012-04-30

    In a series of pump and probe experiments, we study the lifetime statistics of a quantum chaotic resonator when the number of open channels is greater than one. Our design embeds a stadium billiard into a two dimensional photonic crystal realized on a silicon-on-insulator substrate. We calculate resonances through a multiscale procedure that combines energy landscape analysis and wavelet transforms. Experimental data is found to follow the universal predictions arising from random matrix theory with an excellent level of agreement.

  13. Source fabrication and lifetime for Li+ ion beams extracted from alumino-silicate sources

    SciTech Connect

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W

    2012-03-05

    A space-charge-limited beam with current densities (J) exceeding 1 mA/cm2 have been measured from lithium alumino-silicate ion sources at a temperature of ~1275 °C. At higher extraction voltages, the source appears to become emission limited with J ≥ 1.5 mA/cm2, and J increases weakly with the applied voltage. A 6.35 mm diameter source with an alumino-silicate coating, ≤0.25 mm thick, has a measured lifetime of ~40 h at ~1275 °C, when pulsed at 0.05 Hz and with pulse length of ~6 μs each. At this rate, the source lifetime was independent of the actual beam charge extracted due to the loss of neutral atoms at high temperature. Finally, the source lifetime increases with the amount of alumino-silicate coated on the emitting surface, and may also be further extended if the temperature is reduced between pulses.

  14. Source fabrication and lifetime for Li+ ion beams extracted from alumino-silicate sources

    SciTech Connect

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.

    2012-04-01

    A space-charge-limited beam with current densities (J) exceeding 1 mA/cm2 have been measured from lithium alumino-silicate ion sources at a temperature of ~1275 °C. At higher extraction voltages, the source appears to become emission limited with J ≥ 1.5 mA/cm2, and J increases weakly with the applied voltage. A 6.35 mm diameter source with an alumino-silicate coating, ≤0.25 mm thick, has a measured lifetime of ~40 h at ~1275 °C, when pulsed at 0.05 Hz and with pulse length of ~6 μs each. At this rate, the source lifetime was independent of the actual beam charge extracted due to the loss of neutral atoms at high temperature. Finally, the source lifetime increases with the amount of alumino-silicate coated on the emitting surface, and may also be further extended if the temperature is reduced between pulses.

  15. Optimization of the Nonradiative Lifetime of Molecular-Beam-Epitaxy (MBE)-Grown Undoped GaAs/AlGaAs Double Heterostructures (DH)

    DTIC Science & Technology

    2013-09-01

    Optimization of the Nonradiative Lifetime of Molecular- Beam-Epitaxy (MBE)-Grown Undoped GaAs/AlGaAs Double Heterostructures (DH) by P...it to the originator. Army Research Laboratory Adelphi, MD 20783-1197 ARL-TR-6660 September 2013 Optimization of the Nonradiative ...REPORT TYPE Final 3. DATES COVERED (From - To) FY2013 4. TITLE AND SUBTITLE Optimization of the Nonradiative Lifetime of Molecular-Beam-Epitaxy

  16. Lifetime of the 1s2s 3S1 metastable level in He-like S14+ measured with an electron beam ion trap

    SciTech Connect

    L?pez-Urrutia, J C; Beiersdorfer, P; Widmann, K

    2006-03-16

    A precision measurement of the lifetime of the lowest exited level of the He-like S{sup 14+} ion carried out at the Livermore EBIT-II electron beam ion trap yielded a value of (703 {+-} 4) ns. Our method extends the range of lifetime measurements accessible with electron beam ion traps into the nanosecond region and improves the accuracy of currently available data for this level by an order of magnitude.

  17. Positron annihilation lifetime study of radiation-damaged natural zircons

    NASA Astrophysics Data System (ADS)

    Roberts, J.; Gaugliardo, P.; Farnan, I.; Zhang, M.; Vance, E. R.; Davis, J.; Karatchevtseva, I.; Knott, R. B.; Mudie, S.; Buckman, S. J.; Sullivan, J. P.

    2016-04-01

    Zircons are a well-known candidate waste form for actinides and their radiation damage behaviour has been widely studied by a range of techniques. In this study, well-characterised natural single crystal zircons have been studied using Positron Annihilation Lifetime Spectroscopy (PALS). In some, but not all, of the crystals that had incurred at least half of the alpha-event damage of ∼1019 α/g required to render them structurally amorphous, PALS spectra displayed long lifetimes corresponding to voids of ∼0.5 nm in diameter. The long lifetimes corresponded to expectations from published Small-Angle X-ray Scattering data on similar samples. However, the non-observation by PALS of such voids in some of the heavily damaged samples may reflect large size variations among the voids such that no singular size can be distinguished or. Characterisation of a range of samples was also performed using scanning electron microscopy, optical absorption spectroscopy, Raman scattering and X-ray scattering/diffraction, with the degree of alpha damage being inferred mainly from the Raman technique and X-ray diffraction. The observed void diameters and intensities of the long lifetime components were changed somewhat by annealing at 700 °C; annealing at 1200 °C removed the voids entirely. The voids themselves may derive from He gas bubbles or voids created by the inclusion of small quantities of organic and hydrous matter, notwithstanding the observation that no voidage was evidenced by PALS in two samples containing hydrous and organic matter.

  18. Averaged initial Cartesian coordinates for long lifetime satellite studies

    NASA Technical Reports Server (NTRS)

    Pines, S.

    1975-01-01

    A set of initial Cartesian coordinates, which are free of ambiguities and resonance singularities, is developed to study satellite mission requirements and dispersions over long lifetimes. The method outlined herein possesses two distinct advantages over most other averaging procedures. First, the averaging is carried out numerically using Gaussian quadratures, thus avoiding tedious expansions and the resulting resonances for critical inclinations, etc. Secondly, by using the initial rectangular Cartesian coordinates, conventional, existing acceleration perturbation routines can be absorbed into the program without further modifications, thus making the method easily adaptable to the addition of new perturbation effects. The averaged nonlinear differential equations are integrated by means of a Runge Kutta method. A typical step size of several orbits permits rapid integration of long lifetime orbits in a short computing time.

  19. Touschek Background and Lifetime Studies for the SuperB Factory

    SciTech Connect

    Boscolo, M.; Biagini, M.; Raimondi, P.; Sullivan, M.; Paoloni, E.; /INFN, Pisa

    2010-08-26

    The novel crab waist collision scheme under test at the DA{Phi}NE Frascati {Phi}-factory finds its natural application to the SuperB project, the asymmetric e{sup +}e{sup -} flavour factory at very high luminosity with relatively low beam currents and reduced backgrounds. The SuperB accelerator design requires a careful choice of beam parameters to reach a good trade-off between different effects. We present here simulation results for the Touschek backgrounds and lifetime obtained for both the low and high energy rings for different machine designs. A first set of horizontal collimators has been studied to stop Touschek particles. A study of the distributions of the Touschek particle losses at the interaction region into the detectors for further investigations is underway.

  20. Study of Chemical Carcinogens by Positron Annihilation Lifetime Spectroscopy

    NASA Astrophysics Data System (ADS)

    Pivtsaev, A. A.; Razov, V. I.; Karasev, A. O.

    2013-11-01

    We have used positron annihilation lifetime spectroscopy to study the carcinogens C21H20BrN3, C4H7Cl2O4P, CCl4, CHCl3, AlF3, C8H12N4O, C6H4Cl2 and the non-carcinogens H2O, AlCl3, CH2Cl2, C2H6OS. We have established a correlation between the annihilation characteristics of the studied compounds and their degree of carcinogenicity.

  1. Study of Ice Particle Formation and Lifetime in Space Environment

    NASA Technical Reports Server (NTRS)

    Jeng, D.

    1972-01-01

    The ice particles are formed when liquid and/or humid gases vent to the space. These submicroscopic ice particles are potential contamination sources of the environments during Skylab operations. The critical size of ice particle and its nucleation rate based on the theory of homogeneous and heterogeneous nucleation by sublimation are analyzed. The equations which are pertinent for studying the growth and evaporation of the ice particles are formulated. The mechanisms affecting the lifetime of ice particle are discussed. The gas dynamic techniques for experimental study of ice particle formation are proposed.

  2. Multiple Myeloma and lifetime occupation: results from the EPILYMPH study

    PubMed Central

    2012-01-01

    Background The EPILYMPH study applied a detailed occupational exposure assessment approach to a large multi-centre case–control study conducted in six European countries. This paper analysed multiple myeloma (MM) risk associated with level of education, and lifetime occupational history and occupational exposures, based on the EPILYMPH data set. Methods 277 MM cases and four matched controls per each case were included. Controls were randomly selected, matching for age (+/− 5 years), centre and gender. Lifetime occupations and lifetime exposure to specific workplace agents was obtained through a detailed questionnaire. Local industrial hygienists assessed likelihood and intensity for specific exposures. The odds ratio and 95% confidence intervals (OR, 95% CI) were calculated for level of education, individual occupations and specific exposures. Unconditional logistic regression models were run for individual occupations and exposures. Results A low level of education was associated with MM OR=1.68 (95% CI 1.02-2.76). An increased risk was observed for general farmers (OR=1.77; 95% CI 1.05-2.99) and cleaning workers (OR=1.69; 95% CI 1.04-2.72) adjusting for level of education. Risk was also elevated, although not significant, for printers (OR=2.06; 95% CI 0.97-4.34). Pesticide exposure over a period of ten years or more increased MM risk (OR=1.62; 95% CI 1.01-2.58). Conclusion These results confirm an association of MM with farm work, and indicate its association with printing and cleaning. While prolonged exposure to pesticides seems to be a risk factor for MM, an excess risk associated with exposure to organic solvents could not be confirmed. PMID:23241100

  3. Ceramic pot filters lifetime study in coastal Guatemala.

    PubMed

    Salvinelli, C; Elmore, A C; García Hernandez, B R; Drake, K D

    2017-02-01

    Ceramic pot filters (CPFs) are an effective means of household water treatment, but the characterization of CPF lifetimes is ongoing. This paper describes a lifetime field study in Guatemala which was made possible by a collaboration between researchers, CPF-using households, and local non-governmental organizations (NGOs). Disinfection data were collected periodically for two years using field coliform enumeration kits as were flow rate data with the assistance of NGO staff. Consumer acceptance was characterized by surveying householders in the four subject villages at the beginning and end of the study. Flow rate data showed that average CPF flow rates decreased below the recommended minimum of 1 L h(-1) after 10 months of use; however, the survey results indicated that the consumers were tolerant of the lower flow rates, and it is reasonable to assume that the daily volume of treated water can be readily increased by refilling the CPFs more frequently. Of greater concern was the finding that disinfection efficacy decreased below the recommended bacterial reduction after 14 months of use because it would not be obvious to users that effectiveness had declined. Finally, the follow-up visits by the researchers and the NGO staff appeared to increase consumer acceptance of the CPFs.

  4. LHC beam-beam compensation studies at RHIC

    SciTech Connect

    Fischer,W.; Abreu, N.; Calaga, R.; Robert-Demolaize, G.; Luo, Y.; Montag, C.

    2009-05-04

    Long-range and head-on beam-beam effects are expected to limit the LHC performance with design parameters. To mitigate long-range effects current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. To reduce the head-on beam-beam effect electron lenses were proposed for both the LHC and RHIC. We present the experimental long-range beam-beam program and report on head-on compensations studies at RHIC, which are based on simulations.

  5. Beam Propagation Experimental Study.

    DTIC Science & Technology

    1983-04-01

    and locating the camera next to the FX-100 output switch . The camera trigger was derived directly from the light emitted by the FX-100 output switch ...Instability 20 ASSTRPACT eContinue an reverse aide it necessary and Identify by block number) )A program of extensively diagnosed experiments to investigate ...primary objectives of this research were to measure the rate of erosion of the headIof the beam, and to investigate resistive instabilities, such as

  6. Beam Propagation Experimental Study.

    DTIC Science & Technology

    1982-03-01

    30- -40- -50 I 0 100 200 300 Time (ns) Figure 2. FX-100 diode voltage and current. The gas- insulated coax was charged to 4.2 MV in order to produce...limit the usable gradient. The voltage standoff capability will be further limited by electron bombardment of the insulators , which may lead to flashover ...the low-pressure window for stable propagation has been inferred from measurements of the time delay for the beam arrival at a given axial position. 8

  7. Sensitivity studies of crystalline beams

    SciTech Connect

    Wei, J.; Sessler, A.M.

    1996-07-01

    The equations of motion are presented, appropriate to interacting charged particles of diverse charge and mass, subject to the external forces produced by various kinds of magnetic fields and rf electric fields in storage rings. These equations have been employed in the molecular dynamics simulations for sensitivity studies of crystalline beams. The two necessary conditions for the formation and maintenance of crystalline beams are summarized. Effects of lattice shear and AG focusing, magnetic field imperfection, and ion neutralization on crystalline beam heating is presented.

  8. Beam lifetime and emittance growth in RHIC under normal operating conditions with the hydrogen gas jet, the cluster-jet and pellet targets

    SciTech Connect

    Trbojevic, D.

    2010-09-01

    The inelastic scattering of the beam and the residual gas molecules in RHIC could represent one of the limitations on the beam life time and emittance growth. This report covers the dominant central nuclear collisions influence on the beam lifetime and transverse emittance growth. The cross sections for the beam-gas electron radiative captures are an order of magnitude smaller. The capture cross sections include the radiative and non-radiative capture, and the capture from the electron-positron pair creation from the 'vacuum capture'.

  9. Lifetime increased cancer risk in mice following exposure to clinical proton beam-generated neutrons.

    PubMed

    Gerweck, Leo E; Huang, Peigen; Lu, Hsiao-Ming; Paganetti, Harald; Zhou, Yenong

    2014-05-01

    To evaluate the life span and risk of cancer following whole-body exposure of mice to neutrons generated by a passively scattered clinical spread-out Bragg peak (SOBP) proton beam. Three hundred young adult female FVB/N mice, 152 test and 148 control, were entered into the experiment. Mice were placed in an annular cassette around a cylindrical phantom, which was positioned lateral to the mid-SOBP of a 165-MeV, clinical proton beam. The average distance from the edge of the mid-SOBP to the conscious active mice was 21.5 cm. The phantom was irradiated with once-daily fractions of 25 Gy, 4 days per week, for 6 weeks. The age at death and cause of death (ie, cancer and type vs noncancer causes) were assessed over the life span of the mice. Exposure of mice to a dose of 600 Gy of proton beam-generated neutrons, reduced the median life span of the mice by 4.2% (Kaplan-Meier cumulative survival, P=.053). The relative risk of death from cancer in neutron exposed versus control mice was 1.40 for cancer of all types (P=.0006) and 1.22 for solid cancers (P=.09). For a typical 60 Gy dose of clinical protons, the observed 22% increased risk of solid cancer would be expected to decrease by a factor of 10. Exposure of mice to neutrons generated by a proton dose that exceeds a typical course of radiation therapy by a factor of 10, resulted in a statistically significant increase in the background incidence of leukemia and a marginally significant increase in solid cancer. The results indicate that the risk of out-of-field second solid cancers from SOBP proton-generated neutrons and typical treatment schedules, is 6 to 10 times less than is suggested by current neutron risk estimates. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Lifetime increased cancer risk in mice following exposure to clinical proton beam generated neutrons

    PubMed Central

    Gerweck, Leo E.; Huang, Peigen; Lu, Hsiao-Ming; Paganetti, Harald; Zhou, Yenong

    2014-01-01

    Purpose To evaluate the lifespan and risk of cancer following whole-body exposure of mice to neutrons generated by a passively scattered clinical SOBP proton beam. Methods and Materials Three hundred young adult female FVB/N mice, 152 test and 148 control, were entered into the experiment. Mice were placed in an annular cassette around a cylindrical phantom, which was positioned lateral to the mid SOBP of a 165 MeV, clinical proton beam. The average distance from the edge of the mid SOBP to the conscious active mice was 21.5 cm. The phantom was irradiated with once daily fractions of 25 Gy, 4 days per week, for 6 weeks. The age at death and cause of death, i.e., cancer and type vs. non-cancer causes, were assessed over the lifespan of the mice. Results Exposure of mice to a dose of 600 Gy of proton beam generated neutrons, reduced the median lifespan of the mice by 4.2% (Kaplan-Meier cumulative survival, P = 0.053). The relative risk of death from cancer in neutron exposed vs. control mice was 1.40 for cancer of all types (P = 0.0006) and 1.22 for solid cancers (P = 0.09). For a typical 60 Gy dose of clinical protons, the observed 22% increased risk of solid cancer would be expected to decrease by a factor of 10. Conclusions Exposure of mice to neutrons generated by a proton dose which exceeds a typical course of radiotherapy by a factor of 10, resulted in a statistically significant increase in the background incidence of leukemia and a marginally significant increase in solid cancer. The results indicate that the risk of out-of-field 2nd solid cancers from SOBP proton generated neutrons and typical treatment schedules, is 6 - 10 times less than is suggested by current neutron risk estimates. PMID:24725699

  11. DC photogun vacuum characterization through photocathode lifetime studies

    SciTech Connect

    Marcy Stutzman; Joseph Grames; Matt Poelker; Kenneth Surles-Law; Philip Adderley

    2007-07-02

    Excellent vacuum is essential for long photocathode lifetimes in DC high voltage photoelectron guns. Vacuum Research at Thomas Jefferson National Accelerator Facility has focused on characterizing the existing vacuum systems at the CEBAF polarized photoinjector and on quantifying improvements for new systems. Vacuum chamber preprocessing, full activation of NEG pumps and NEG coating the chamber walls should improve the vacuum within the electron gun, however, pressure measurement is difficult at pressures approaching the extreme-high-vacuum (XHV) region and extractor gauge readings are not significantly different between the improved and original systems. The ultimate test of vacuum in a DC high voltage photogun is the photocathode lifetime, which is limited by the ionization and back-bombardment of residual gasses. Discussion will include our new load-locked gun design as well as lifetime measurements in both our operational and new photo-guns, and the correlations between measured vacuum and lifetimes will be investigated.

  12. Vacancy profile in reverse osmosis membranes studied by positron annihilation lifetime measurements and molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Shimazu, A.; Goto, H.; Shintani, T.; Hirose, M.; Suzuki, R.; Kobayashi, Y.

    2013-06-01

    The positron annihilation technique using a slow positron beam can be used for the study of the vacancy profiles in typical reverse osmosis (RO) membranes. In this study, the vacancy profile in the polyamide membrane that exhibits a high permselectivity between ions and water was studied using the positron annihilation technique and molecular dynamics simulations. Ortho-positronium (o-Ps) lifetimes in the surface region of the membranes were evaluated by using a slow positron beam. The diffusion behavior of Na+ and water in the polyamides was simulated by molecular dynamics (MD) methods using the TSUBAME2 supercomputer at the Tokyo Institute of Technology and discussed with the vacancy profile probed by the o-Ps. The results suggested that the large hydration size of Na+ compared to the vacancy size in the polyamides contributes to the increased diffusivity selectivity of water/Na+ that is related to the NaCl desalination performance of the membrane. Both the hydration size of the ions and the vacancy size appeared to be significant parameters to discuss the diffusivity selectivity of water/ions in typical polyamide membranes.

  13. Los Alamos National Laboratory W76 Pit Tube Lifetime Study

    SciTech Connect

    Abeln, Terri G.

    2012-04-25

    A metallurgical study was requested as part of the Los Alamos National Laboratory (LANL) W76-1 life-extension program (LEP) involving a lifetime analysis of type 304 stainless steel pit tubes subject to repeat bending loads during assembly and disassembly operations at BWXT/Pantex. This initial test phase was completed during the calendar years of 2004-2006 and the report not issued until additional recommended tests could be performed. These tests have not been funded to this date and therefore this report is considered final. Tubes were reportedly fabricated according to Rocky Flats specification P14548 - Seamless Type 304 VIM/VAR Stainless Steel Tubing. Tube diameter was specified as 0.125 inches and wall thickness as 0.028 inches. A heat treat condition is not specified and the hardness range specification can be characteristic of both 1/8 and 1/4 hard conditions. Properties of all tubes tested were within specification. Metallographic analysis could not conclusively determine a specified limit to number of bends allowable. A statistical analysis suggests a range of 5-7 bends with a 99.95% confidence limit. See the 'Statistical Analysis' section of this report. The initial phase of this study involved two separate sets of test specimens. The first group was part of an investigation originating in the ESA-GTS [now Gas Transfer Systems (W-7) Group]. After the bend cycle test parameters were chosen (all three required bends subjected to the same amount of bend cycles) and the tubes bent, the investigation was transferred to Terri Abeln (Metallurgical Science and Engineering) for analysis. Subsequently, another limited quantity of tubes became available for testing and were cycled with the same bending fixture, but with different test parameters determined by T. Abeln.

  14. Positron lifetime studies in vinyl polymers of medical importance

    NASA Astrophysics Data System (ADS)

    Ferreira Marques, M. F.; Gordo, P. M.; Gil, C. Lopes; Kajcsos, Zs.; Gil, M. H.; Mariz, M. J.; de Lima, A. P.

    2003-10-01

    Vinyl polymers used as artificial lens implants in ophthalmology were investigated by positron lifetime spectroscopy. The structure of these polymers with free volumes offers the possibility of charging them with anti-inflammatory drugs for sustained release. A correlation between the amount of normalised free volume and the ratio of the methyl methacrylate to ethyl-hexyl-acrylate, used as polymerisation monomers, was found.

  15. Studies of beam heating of proton beam profile monitor SEM's

    SciTech Connect

    Pavlovich, Zarko; Osiecki, Thomas H.; Kopp, Sacha E.; /Texas U.

    2005-05-01

    The authors present calculations of the expected temperature rise of proton beam profile monitors due to beam heating. The profile monitors are secondary emission monitors (SEM's) to be made of Titanium foils. The heating is studied to understand whether there is any loss of tension or alignment of such devices. Additionally, calculations of thermally-induced dynamic stress are presented. Ti foil is compared to other materials and also to wire SEM's. The calculations were initially performed for the NuMI beam, where the per-pulse intensity is quite high; for completeness the calculations are also performed for other beam energies and intensities.

  16. Lifetime socioeconomic position and mortality: prospective observational study.

    PubMed Central

    Smith, G. D.; Hart, C.; Blane, D.; Gillis, C.; Hawthorne, V.

    1997-01-01

    OBJECTIVES: To assess the influence of socioeconomic position over a lifetime on risk factors for cardiovascular disease, on morbidity, and on mortality from various causes. DESIGN: Prospective observational study with 21 years of follow up. Social class was determined as manual or non-manual at three stages of participants' lives: from the social class of their father's job, the social class of their first job, and the social class of their job at the time of screening. A cumulative social class indicator was constructed, ranging from non-manual social class at all three stages of life to manual social class at all three stages. SETTING: 27 workplaces in the west of Scotland. PARTICIPANTS: 5766 men aged 35-64 at the time of examination. MAIN OUTCOME MEASURES: Prevalence and level of risk factors for cardiovascular disease; morbidity; and mortality from broad causes of death. RESULTS: From non-manual social class locations at all three life stages to manual at all stages there were strong positive trends for blood pressure, body mass index, current cigarette smoking, angina, and bronchitis. Inverse trends were seen for height, cholesterol concentration, lung function, and being an ex-smoker. 1580 men died during follow up. Age adjusted relative death rates in comparison with the men of non-manual social class locations at all three stages of life were 1.29 (95% confidence interval 1.08 to 1.56) in men of two non-manual and one manual social class; 1.45 (1.21 to 1.73) in men of two manual and one non-manual social class; and 1.71 (1.46 to 2.01) in men of manual social class at all three stages. Mortality from cardiovascular disease showed a similar graded association with cumulative social class. Mortality from cancer was mainly raised among men of manual social class at all three stages. Adjustment for a wide range of risk factors caused little attenuation in the association of cumulative social class with mortality from all causes and from cardiovascular disease

  17. Lifetime experimental study of graphite cathode for relativistic backward wave oscillator

    SciTech Connect

    Wu, Ping; Sun, Jun; Chen, Changhua

    2016-07-21

    Graphite cathodes are widely used due to their good emission properties, especially their long lifetime. Some previous papers have researched their lifetime under certain conditions and uncovered some important phenomena. This paper is dedicated to research the lifetime of the graphite cathode under higher power. In the lifetime test, the voltage and current amplitudes are about 970 kV and 9.7 kA, respectively. The repetition rate is 20 Hz. An X-band relativistic backward wave oscillator is used to generate high power microwave by utilizing the electron beam energy. The experimental results demonstrate that the emission property of the graphite cathode remains quite stable during 10{sup 5} pulses, despite some slight deteriorations regarding the beam and microwave parameters. The macroscopic morphology change of the cathode blade due to material evaporation is observed by a laser microscope. The mass loss of the graphite cathode is about 60 μg/C. Meanwhile, the observation by a scanning electron microscope uncovers that the original numerous flaky micro-structures are totally replaced by a relatively smooth surface at the mid region of the cathode blade and a large number of new micro-protrusions at the blade edges during the lifetime test.

  18. Quantifying lifetime exposure to ultraviolet radiation in the epidemiology of cutaneous malignant melanoma: A pilot study

    SciTech Connect

    Lea, C.S.; Selvin, S. |; Buffler, P.A.; Scotto, J.; Berwick, M.

    1992-10-01

    This pilot study uses a unique method to calculate cumulative lifetime exposure to, ultraviolet radiation-b to determine if this refined method would indicate differences in lifetime cumulative UVB exposure between age and sex matched controls. Forty-four age and sex matched cases and controls demonstrated no significant difference in mean cumulative lifetime UVB exposure based on the duration and location of residence. This pilot study suggests that further analysis of the dataset should be conducted to determine if the cumulative lifetime exposure hypothesis is of primary importance regarding the association between UVB exposure and development of cutaneous malignant melanoma.

  19. Quantifying lifetime exposure to ultraviolet radiation in the epidemiology of cutaneous malignant melanoma: A pilot study

    SciTech Connect

    Lea, C.S.; Selvin, S. . Dept. of Biomedical and Environmental Health Sciences Lawrence Berkeley Lab., CA ); Buffler, P.A. . Dept. of Biomedical and Environmental Health Sciences); Scotto, J. . Biostatistics Branch); Berwick, M. (Cancer Pre

    1992-10-01

    This pilot study uses a unique method to calculate cumulative lifetime exposure to, ultraviolet radiation-b to determine if this refined method would indicate differences in lifetime cumulative UVB exposure between age and sex matched controls. Forty-four age and sex matched cases and controls demonstrated no significant difference in mean cumulative lifetime UVB exposure based on the duration and location of residence. This pilot study suggests that further analysis of the dataset should be conducted to determine if the cumulative lifetime exposure hypothesis is of primary importance regarding the association between UVB exposure and development of cutaneous malignant melanoma.

  20. Early Amyloidogenic Oligomerization Studied through Fluorescence Lifetime Correlation Spectroscopy

    PubMed Central

    Paredes, Jose M.; Casares, Salvador; Ruedas-Rama, Maria J.; Fernandez, Elena; Castello, Fabio; Varela, Lorena; Orte, Angel

    2012-01-01

    Amyloidogenic protein aggregation is a persistent biomedical problem. Despite active research in disease-related aggregation, the need for multidisciplinary approaches to the problem is evident. Recent advances in single-molecule fluorescence spectroscopy are valuable for examining heterogenic biomolecular systems. In this work, we have explored the initial stages of amyloidogenic aggregation by employing fluorescence lifetime correlation spectroscopy (FLCS), an advanced modification of conventional fluorescence correlation spectroscopy (FCS) that utilizes time-resolved information. FLCS provides size distributions and kinetics for the oligomer growth of the SH3 domain of α-spectrin, whose N47A mutant forms amyloid fibrils at pH 3.2 and 37 °C in the presence of salt. The combination of FCS with additional fluorescence lifetime information provides an exciting approach to focus on the initial aggregation stages, allowing a better understanding of the fibrillization process, by providing multidimensional information, valuable in combination with other conventional methodologies. PMID:22949804

  1. Perceived lifetime risk for cardiovascular disease (from the Dallas Heart Study).

    PubMed

    Petr, Elisabeth Joye; Ayers, Colby R; Pandey, Ambarish; de Lemos, James A; Powell-Wiley, Tiffany M; Khera, Amit; Lloyd-Jones, Donald M; Berry, Jarett D

    2014-07-01

    Lifetime risk estimation for cardiovascular disease (CVD) has been proposed as a useful strategy to improve risk communication in the primary prevention setting. However, the perception of lifetime risk for CVD is unknown. We included 2,998 subjects from the Dallas Heart Study. Lifetime risk for developing CVD was classified as high (≥39%) versus low (<39%) according to risk factor burden as described in our previously published algorithm. Perception of lifetime risk for myocardial infarction was assessed by way of a 5-point scale. Baseline characteristics were compared across levels of perceived lifetime risk. Multivariable logistic regression analyses were performed to determine the association of participant characteristics with level of perceived lifetime risk for CVD and with correctness of perceptions. Of the 2,998 participants, 64.8% (n = 1,942) were classified as having high predicted lifetime risk for CVD. There was significant discordance between perceived and predicted lifetime risk. After multivariable adjustment, family history of premature myocardial infarction, high self-reported stress, and low perceived health were all strongly associated with high perceived lifetime risk (odds ratio [OR] 2.37, 95% confidence interval [CI] 1.72 to 3.27; OR 2.17, 95% CI 1.66 to 2.83; and OR 2.71, 95% CI 2.09 to 3.53; respectively). However, the association between traditional CVD risk factors and high perceived lifetime risk was more modest. In conclusion, misperception of lifetime risk for CVD is common and frequently reflects the influence of factors other than traditional risk factor levels. These findings highlight the importance of effectively communicating the significance of traditional risk factors in determining the lifetime risk for CVD. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Perceived Lifetime Risk for Cardiovascular Disease (From the Dallas Heart Study)

    PubMed Central

    Petr, Elisabeth Joye; Ayers, Colby; Pandey, Ambarish; de Lemos, James; Powell-Wiley, Tiffany M.; Khera, Amit; Lloyd-Jones, Donald M.; Berry, Jarett D.

    2014-01-01

    Lifetime risk estimation for cardiovascular disease (CVD) has been proposed as a useful strategy to improve risk communication in the primary prevention setting. However, the perception of lifetime risk for CVD is unknown. We included 2,998 individuals from the Dallas Heart Study. Lifetime risk for developing CVD was classified as high (≥39%) vs. low (<39%) according to risk factor burden as described in our previously published algorithm. Perception of lifetime risk for myocardial infarction was assessed via a 5-point scale. Baseline characteristics were compared across levels of perceived lifetime risk. Multivariable logistic regression analyses were performed to determine the association of participant characteristics with level of perceived lifetime risk for CVD and with correctness of perceptions. 64.8% (1942/2998) of participants were classified as high predicted lifetime risk for CVD. There was significant discordance between perceived and predicted lifetime risk. After multivariable adjustment, family history of premature MI, high self-reported stress, and low perceived health were all strongly associated with high perceived lifetime risk (OR [95% CI]: 2.37 [1.72–3.27], 2.17 [1.66–2.83], and 2.71 [2.09–3.53]). However, the association between traditional CVD risk factors and high perceived lifetime risk was more modest. In conclusion, misperception of lifetime risk for CVD is common and frequently reflects the influence of factors other than traditional risk factor levels. These findings highlight the importance of effectively communicating the significance of traditional risk factors in determining the lifetime risk for CVD. PMID:24834788

  3. Beam Studies with Electron Columns

    SciTech Connect

    Shiltsev, V.; Valishev, A.; Kuznetsov, G.; Kamerdzhiev, V.; Romanov, A.; /Novosibirsk, IYF

    2009-04-01

    We report preliminary results of experimental studies of 'electron columns' in the Tevatron and in a specialized test setup. In the Tevatron, a beam of 150 GeV protons ionizes residual gas and ionization electrons are stored in an electrostatic trap immersed into strong longitudinal magnetic field. Shifts of proton betatron frequencies are observed. In the test setup, we observe effects pointing to accumulation and escape of ionization electrons.

  4. Lifetime studies in H2/Br2 fuel cells

    NASA Astrophysics Data System (ADS)

    Barna, G. G.; Frank, S. N.; Teherani, T. H.; Weedon, L. D.

    1984-09-01

    A fully computerized system has been set up for the life testing of H2 electrodes in 48 percent HBr, and of H2/Br2 fuel cells. Given a fuel cell design with dry H2 and no anolyte loop, the prime parameters influencing the operating lifetime are the hydrophobicity of the anode and the electrolyte transport property of the membrane. A systematic optimization of all the parameters has generated fuel cells that have operated for 10,000h at 2 A/sq in., with no significant degradation.

  5. Beam Beam Simulation Studies for NLC And SLC2000

    SciTech Connect

    Thompson, K.A.; Chen, P.; Irwin, J.; Zimmermann, F.; /SLAC

    2010-05-27

    We apply and modify the computer codes CAIN(P.Chen, G.Horton-Smith, T.Ohgaki, A.W.Weidemann, K.Yokoya, contributed to Workshop on Gamma-Gamma Colliders, Berkeley, CA, March 28-31, 1994; SLAC-PUB-6583.) and GUINEAPIG(D.Schulte (DESY), unpublished.) to make detailed studies of the beam-beam interaction in the SLAC design for a future linear collider (NLC), as well as to the proposed SLC2000 project. Using realistic beam distributions, we present simulations related to the tuning and optimization of luminosity in SLC2000 and NLC.

  6. Low Emittance Electron Beam Studies

    SciTech Connect

    Tikhoplav, Rodion

    2006-01-01

    We have studied the properties of a low emittance electron beam produced by laser pulses incident onto an rf gun photocathode. The experiments were carried out at the A0 photoinjector at Fermilab. Such beam studies are necessary for fixing the design of new Linear Colliders as well as for the development of Free Electron Lasers. An overview of the A0 photoinjector is given in Chapter 1. In Chapter 2 we describe the A0 photoinjector laser system. A stable laser system is imperative for reliable photoinjector operation. After the recent upgrade, we have been able to reach a new level of stability in the pulse-to-pulse fluctuations of the pulse amplitude, and of the temporal and transverse profiles. In Chapter 3 we present a study of transverse emittance versus the shape of the photo-cathode drive-laser pulse. For that purpose a special temporal profile laser shaping device called a pulse-stacker was developed. In Chapter 4 we discuss longitudinal beam dynamics studies using a two macro-particle bunch; this technique is helpful in analyzing pulse compression in the magnetic chicane, as well as velocity bunching effects in the rf-gun and the 9-cell accelerating cavity. In Chapter 5 we introduce a proposal for laser acceleration of electrons. We have developed a laser functioning on the TEM*01 mode, a mode with a longitudinal electric field component which is suitable for such a process. Using this technique at energies above 40 MeV, one would be able to observe laser-based acceleration.

  7. Beam instability studies for the SSC

    SciTech Connect

    Chou, W.

    1994-09-01

    Beam instability studies of the Superconducting Super Collider (SSC) during the period 1989--1993 are briefly reviewed in this paper. Various topics are covered: single bunch and multi-bunch, single beam and beam-beam, parasitic heating and active feedback, etc. Although the SSC will not be built, many of the results obtained from these studies remain as useful references to the accelerator community.

  8. Lifetime total and beverage specific - alcohol intake and prostate cancer risk: a case-control study

    PubMed Central

    Barba, Maddalena; McCann, Susan E; Schünemann, Holger J; Stranges, Saverio; Fuhrman, Barbara; De Placido, Sabino; Carruba, Giuseppe; Freudenheim, Jo L; Trevisan, Maurizio; Russell, Marcia; Nochajski, Tom; Muti, Paola

    2004-01-01

    Background We investigated lifetime alcohol consumption and prostate cancer risk in a case-control study conducted in Buffalo, NY (1998–2001). Methods The study included 88 men, aged 45 to 85 years with incident, histologically-confirmed prostate cancer and 272 controls. We conducted extensive in-person interviews regarding lifetime alcohol consumption and other epidemiologic data. Results Prostate cancer risk was not associated with lifetime intake of total and beverage specific ethanol. In addition we found no association with number of drinks per day (average drinks per day over the lifetime) or drinks per drinking day (average drinks per day on drinking days only over the lifetime). However, we observed an inverse association with the total number of drinking years. Men in the lowest tertile of total drinking years had a two-fold prostate cancer risk than men in the highest tertile (OR 2.16, 95% CI 0.98–4.78, p for trend <0.05). Conclusion Our results suggest that alcohol intake distribution across lifetime may play a more important role in prostate cancer etiology than total lifetime consumption. PMID:15588306

  9. Collimation Studies with Hollow Electron Beams

    SciTech Connect

    Stancari, G.; Annala, G.; Johnson, T.R.; Saewert, G.W.; Shiltsev, V.; Still, D.A.; Valishev, A.; /Fermilab

    2011-08-01

    Recent experimental studies at the Fermilab Tevatron collider have shown that magnetically confined hollow electron beams can act as a new kind of collimator for high-intensity beams in storage rings. In a hollow electron beam collimator, electrons enclose the circulating beam. Their electric charge kicks halo particles transversely. If their distribution is axially symmetric, the beam core is unaffected. This device is complementary to conventional two-stage collimation systems: the electron beam can be placed arbitrarily close to the circulating beam; and particle removal is smooth, so that the device is a diffusion enhancer rather than a hard aperture limitation. The concept was tested in the Tevatron collider using a hollow electron gun installed in one of the existing electron lenses. We describe some of the technical aspects of hollow-beam scraping and the results of recent measurements.

  10. Beam simulation studies of ECR beam extraction and low energy beam transport for FRIB

    SciTech Connect

    Ren, Haitao Pozdeyev, Eduard; Lund, Steven M.; Machicoane, Guillaume; Wu, Xiaoyu; Morgan, Glenn

    2016-02-15

    To meet the beam power requirements of 400 kW at the fragmentation target for facility for Rare Isotope Beams (FRIB), simultaneous acceleration of two-charge states should be used for heavier ions. These intense multi-charged ion beams will be produced by a 28 GHz electron cyclotron resonance (ECR) ion source at a high voltage of 35 kV. After extraction, the ion beam will be pre-accelerated to 12 keV/u with a 50 kV platform, transported down to an achromatic charge state selection (CSS) system followed by a vertical transport line, and then injected into a radio frequency quadrupole accelerator. The TRACK code developed at ANL is used to perform the simulations of the ECR beam extraction and low energy beam transport for FRIB. In this study, we include the magnetic field of ECR ion source into simulations. Different initial beam conditions as well as different space charge neutralization levels are tested for the ECR beamline. The beam loss in CSS system and the corresponding protective measures are discussed. The detailed results about the beam dynamic simulation and beam loss in CSS system will be presented in this paper.

  11. Beam simulation studies of ECR beam extraction and low energy beam transport for FRIB

    NASA Astrophysics Data System (ADS)

    Ren, Haitao; Pozdeyev, Eduard; Lund, Steven M.; Machicoane, Guillaume; Wu, Xiaoyu; Morgan, Glenn

    2016-02-01

    To meet the beam power requirements of 400 kW at the fragmentation target for facility for Rare Isotope Beams (FRIB), simultaneous acceleration of two-charge states should be used for heavier ions. These intense multi-charged ion beams will be produced by a 28 GHz electron cyclotron resonance (ECR) ion source at a high voltage of 35 kV. After extraction, the ion beam will be pre-accelerated to 12 keV/u with a 50 kV platform, transported down to an achromatic charge state selection (CSS) system followed by a vertical transport line, and then injected into a radio frequency quadrupole accelerator. The TRACK code developed at ANL is used to perform the simulations of the ECR beam extraction and low energy beam transport for FRIB. In this study, we include the magnetic field of ECR ion source into simulations. Different initial beam conditions as well as different space charge neutralization levels are tested for the ECR beamline. The beam loss in CSS system and the corresponding protective measures are discussed. The detailed results about the beam dynamic simulation and beam loss in CSS system will be presented in this paper.

  12. Preliminary studies on a variable energy positron annihilation lifetime spectroscopy system

    NASA Astrophysics Data System (ADS)

    Kwan, P. Y.; Cheung, C. K.; Beling, C. D.; Fung, S.

    2006-02-01

    There are many advantages in being able to perform positron annihilation lifetime spectroscopy (PALS) using a variable energy positron beam, the most obvious being the easy identification of different defect types at different depths. The difficulty in conducting variable energy (VE) PALS studies lies in the fact that a "start" signal is required to signal the entry of the positron into the target. Two methods have been used to overcome this problem, namely the bunching technique, which employs radio frequency (RF) cavities and choppers, and secondly the use of secondary electrons emitted from the target. The latter technique is in terms of experimental complexity much simpler, but has in the past suffered from poor time resolution (typically ˜500 ps). In this work, we present a series of computer simulations of a design based on the secondary electron emission from thin C-foils in transmission mode which shows that significant improvements in time resolution can be made with resolutions ˜200 ps being in principle possible.

  13. Studies of beam dynamics in relativistic klystron two- beam accelerators

    NASA Astrophysics Data System (ADS)

    Lidia, Steven Michael

    Two-beam accelerators (TBAs) based upon free-electron lasers (FELs) or relativistic klystrons (RK-TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band (~8-12 GHz) through Ka-band (~30-35 GHz) frequency regions. A new method of simulating the beam dynamics in accelerators of this type has been developed in this dissertation. There are three main components to this simulation. The first is a tracking algorithm to generate nonlinear transfer maps for pushing noninteracting particles through the external fields. A mapping algorithm is used so that tens or hundreds of thousands of macroparticles can be pushed from the solution of a few hundreds of differential equations. This is a great cost-savings device from the standpoint of CPU cycles. It can increase by several orders of magnitude the number of macroparticles that take place in the simulation, enabling more accurate modeling of the evolution of the beam distribution and enhanced sensitivity to effects due to the beam's halo. The second component is a 3D Particle-In-Cell (PIC) algorithm that solves a set of Helmholtz equations for the self-fields, including the conducting boundary condition, and generates impulses that are interleaved with the nonlinear maps by means of a split- operator algorithm. The Helmholtz equations are solved by a multi-grid algorithm. The third component is an equivalent circuit equation solver that advances the modal rf cavity fields in time due to excitation by the modulated beam. The beam-cavity interaction is analyzed and divided naturally into two distinct times scales. The RTA project is described, and the simulation code is used to design the latter portions of the experiment. Detailed calculations of the beam dynamics and of the rf cavity output are presented and discussed. A beamline design is presented that will generate nearly 1.2 TW of power from 40 input, gain

  14. Lifetime Pesticide Use and Telomere Shortening among Male Pesticide Applicators in the Agricultural Health Study

    PubMed Central

    Hou, Lifang; Andreotti, Gabriella; Baccarelli, Andrea A.; Savage, Sharon; Hoppin, Jane A.; Sandler, Dale P.; Barker, Joseph; Zhu, Zhong-Zheng; Hoxha, Mirjam; Dioni, Laura; Zhang, Xiao; Koutros, Stella; Freeman, Laura E. Beane

    2013-01-01

    Background: Telomere length (TL) in surrogate tissues may be influenced by environmental exposures. Objective: We aimed to determine whether lifetime pesticides use is associated with buccal cell TL. Methods: We examined buccal cell TL in relation to lifetime use of 48 pesticides for 1,234 cancer-free white male pesticide applicators in the Agricultural Health Study (AHS), a prospective cohort study of 57,310 licensed pesticide applicators. Participants provided detailed information on lifetime use of 50 pesticides at enrollment (1993–1997). Buccal cells were collected from 1999 to 2006. Relative telomere length (RTL) was measured using quantitative real-time polymerase chain reaction. We used linear regression modeling to evaluate the associations between specific pesticides and the logarithm of RTL, adjusting for age at buccal cell collection, state of residence, applicator license type, chewing tobacco use, and total lifetime days of all pesticide use. Results: The mean RTL for participants decreased significantly in association with increased lifetime days of pesticide use for alachlor (p = 0.002), 2,4-dichlorophenoxyacetic acid (2,4-D; p = 0.004), metolachlor (p = 0.01), trifluralin (p = 0.05), permethrin (for animal application) (p = 0.02), and toxaphene (p = 0.04). A similar pattern of RTL shortening was observed with the metric lifetime intensity-weighted days of pesticide use. For dichlorodiphenyltrichloroethane (DDT), we observed significant RTL shortening for lifetime intensity-weighted days (p = 0.04), but not for lifetime days of DDT use (p = 0.08). No significant RTL lengthening was observed for any pesticide. Conclusion: Seven pesticides previously associated with cancer risk in the epidemiologic literature were inversely associated with RTL in buccal cell DNA among cancer-free pesticide applicators. Replication of these findings is needed because we cannot rule out chance or fully rule out bias. PMID:23774483

  15. Lifetime Physical Activity and Breast Cancer: a Case-Control Study in Kelantan, Malaysia.

    PubMed

    Yen, Siew Hwa; Knight, A; Krishna, Mbv; Muda, Wmw; Rufai, Aa

    2016-01-01

    Physical inactivity has been identified as the fourth leading risk factor for global mortality and is associated with increased breast cancer diagnosis and recurrence. To examine the association between adult lifetime physical activity and breast cancer risk in a case-control analysis. This study involved 122 cases of breast cancer and 121 controls in the state of Kelantan in Malaysia. A comprehensive measure of lifetime physical activity was used to assess occupational, household, and recreational/sports activity. For every type of activity, a metabolic equivalent (MET) score was assigned using the compendium of physical activities. MET-hours/week per year for all types of activities at different levels of intensities for different age groups were calculated. Logistic regression analysis was used to estimate odds ratios between various measures of physical activity and breast cancer risk. The mean MET-hours/week per year for all activities were 120.0 and 132.9 of MET-hours/week per year for cases and controls respectively. Household activities accounted for about 70% of the total lifetime physical activities. Only about 2.5% of the total lifetime physical activities were in the form of recreational/sports. This study found no association between lifetime occupational and recreational/sports physical activities with breast cancer risk among Kelantanese women. However, higher intensity lifetime household activities seemed to significantly reduce risk of breast cancer.

  16. The Golden Retriever Lifetime Study: establishing an observational cohort study with translational relevance for human health

    PubMed Central

    Guy, Michael K.; Page, Rodney L.; Jensen, Wayne A.; Olson, Patricia N.; Haworth, J. David; Searfoss, Erin E.; Brown, Diane E.

    2015-01-01

    The Golden Retriever Lifetime Study (GRLS) is the first prospective longitudinal study attempted in veterinary medicine to identify the major dietary, genetic and environmental risk factors for cancer and other important diseases in dogs. The GRLS is an observational study that will follow a cohort of 3000 purebred Golden Retrievers throughout their lives via annual online questionnaires from the dog owner and annual physical examinations and collection of biological samples by the primary care veterinarian. The field of comparative medicine investigating naturally occurring disorders in pets is specifically relevant to the many diseases that have a genetic basis for disease in both animals and humans, including cancer, blindness, metabolic and behavioural disorders and some neurodegenerative disorders. The opportunity for the GRLS to provide high-quality data for translational comparative medical initiatives in several disease categories is great. In particular, the opportunity to develop a lifetime dataset of lifestyle and activity, environmental exposure and diet history combined with simultaneous annual biological sample sets and detailed health outcomes will provide disease incidence data for this cohort of geographically dispersed dogs and associations with a wide variety of potential risk factors. The GRLS will provide a lifetime historical context, repeated biological sample sets and outcomes necessary to interrogate complex associations between genes and environmental influences and cancer. PMID:26056371

  17. Product lifetime, energy efficiency and climate change: A case study of air conditioners in Japan.

    PubMed

    Nishijima, Daisuke

    2016-10-01

    This study proposed a modelling technique for estimating life-cycle CO2 emissions of durable goods by considering changes in product lifetime and energy efficiency. The stock and flow of durable goods was modelled by Weibull lifetime distributions and the trend in annual energy efficiency (i.e., annual electricity consumption) of an "average" durable good was formulated as a reverse logistic curve including a technologically critical value (i.e., limit energy efficiency) with respect to time. I found that when the average product lifetime is reduced, there is a trade-off between the reduction in emissions during product use (use phase), due to the additional purchases of new, more energy-efficient air conditioners, and the increase in emissions arising from the additional production of new air conditioners stimulated by the reduction of the average product lifetime. A scenario analysis focused on residential air conditioners in Japan during 1972-2013 showed that for a reduction of average lifetime of 1 year, if the air conditioner energy efficiency limit can be improved by 1.4% from the estimated current efficiency level, then CO2 emissions can be reduced by approximately the same amount as for an extension of average product lifetime of 1 year.

  18. Alpha-induced reaction studies using low-energy RI beams at CRIB

    SciTech Connect

    Yamaguchi, H.; Kahl, D.; Hu, J.; Kubono, S.; Hayakawa, S.; Hashimoto, T.

    2012-11-12

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Studies on proton and alpha resonance scatterings, ({alpha}, p) reactions, and other types of measurements ({beta}-decay lifetimes etc.) have been performed using RI beams at CRIB, motivated by interests on astrophysical reactions and exotic nuclear structure. Among the studies at CRIB, the measurement of {sup 7}Li+{alpha}/{sup 7}Be+{alpha} resonant scatterings are presented.

  19. Lifetime of anode polymer in magnetically insulated ion diodes for high-intensity pulsed ion beam generation

    SciTech Connect

    Zhu, X. P.; Dong, Z. H.; Han, X. G.; Xin, J. P.; Lei, M. K.

    2007-02-15

    Generation of high-intensity pulsed ion beam (HIPIB) has been studied experimentally using polyethylene as the anode polymer in magnetically insulated ion diodes (MIDs) with an external magnetic field. The HIPIB is extracted from the anode plasma produced during the surface discharging process on polyethylene under the electrical and magnetic fields in MIDs, i.e., high-voltage surface breakdown (flashover) with bombardments by electrons. The surface morphology and the microstructure of the anode polymer are characterized using scanning electron microscopy and differential scanning calorimetry, respectively. The surface roughening of the anode polymer results from the explosive release of trapped gases or newly formed gases under the high-voltage discharging, leaving fractured surfaces with bubble formation. The polyethylene in the surface layer degrades into low-molecular-weight polymers such as polyethylene wax and paraffin under the discharging process. Both the surface roughness and the fraction of low molecular polymers apparently increase as the discharging times are prolonged for multipulse HIPIB generation. The changes in the surface morphology and the composition of anode polymer lead to a noticeable decrease in the output of ion beam intensity, i.e., ion current density and diode voltage, accompanied with an increase in instability of the parameters with the prolonged discharge times. The diode voltage (or surface breakdown voltage of polymer) mainly depends on the surface morphology (or roughness) of anode polymers, and the ion current density on the composition of anode polymers, which account for the two stages of anode polymer degradation observed experimentally, i.e., stage I which has a steady decrease of the two parameters and stage II which shows a slow decrease, but with an enhanced fluctuation of the two parameters with increasing pulses of HIPIB generation.

  20. Lifetime of anode polymer in magnetically insulated ion diodes for high-intensity pulsed ion beam generation.

    PubMed

    Zhu, X P; Dong, Z H; Han, X G; Xin, J P; Lei, M K

    2007-02-01

    Generation of high-intensity pulsed ion beam (HIPIB) has been studied experimentally using polyethylene as the anode polymer in magnetically insulated ion diodes (MIDs) with an external magnetic field. The HIPIB is extracted from the anode plasma produced during the surface discharging process on polyethylene under the electrical and magnetic fields in MIDs, i.e., high-voltage surface breakdown (flashover) with bombardments by electrons. The surface morphology and the microstructure of the anode polymer are characterized using scanning electron microscopy and differential scanning calorimetry, respectively. The surface roughening of the anode polymer results from the explosive release of trapped gases or newly formed gases under the high-voltage discharging, leaving fractured surfaces with bubble formation. The polyethylene in the surface layer degrades into low-molecular-weight polymers such as polyethylene wax and paraffin under the discharging process. Both the surface roughness and the fraction of low molecular polymers apparently increase as the discharging times are prolonged for multipulse HIPIB generation. The changes in the surface morphology and the composition of anode polymer lead to a noticeable decrease in the output of ion beam intensity, i.e., ion current density and diode voltage, accompanied with an increase in instability of the parameters with the prolonged discharge times. The diode voltage (or surface breakdown voltage of polymer) mainly depends on the surface morphology (or roughness) of anode polymers, and the ion current density on the composition of anode polymers, which account for the two stages of anode polymer degradation observed experimentally, i.e., stage I which has a steady decrease of the two parameters and stage II which shows a slow decrease, but with an enhanced fluctuation of the two parameters with increasing pulses of HIPIB generation.

  1. Lifetime of anode polymer in magnetically insulated ion diodes for high-intensity pulsed ion beam generation

    NASA Astrophysics Data System (ADS)

    Zhu, X. P.; Dong, Z. H.; Han, X. G.; Xin, J. P.; Lei, M. K.

    2007-02-01

    Generation of high-intensity pulsed ion beam (HIPIB) has been studied experimentally using polyethylene as the anode polymer in magnetically insulated ion diodes (MIDs) with an external magnetic field. The HIPIB is extracted from the anode plasma produced during the surface discharging process on polyethylene under the electrical and magnetic fields in MIDs, i.e., high-voltage surface breakdown (flashover) with bombardments by electrons. The surface morphology and the microstructure of the anode polymer are characterized using scanning electron microscopy and differential scanning calorimetry, respectively. The surface roughening of the anode polymer results from the explosive release of trapped gases or newly formed gases under the high-voltage discharging, leaving fractured surfaces with bubble formation. The polyethylene in the surface layer degrades into low-molecular-weight polymers such as polyethylene wax and paraffin under the discharging process. Both the surface roughness and the fraction of low molecular polymers apparently increase as the discharging times are prolonged for multipulse HIPIB generation. The changes in the surface morphology and the composition of anode polymer lead to a noticeable decrease in the output of ion beam intensity, i.e., ion current density and diode voltage, accompanied with an increase in instability of the parameters with the prolonged discharge times. The diode voltage (or surface breakdown voltage of polymer) mainly depends on the surface morphology (or roughness) of anode polymers, and the ion current density on the composition of anode polymers, which account for the two stages of anode polymer degradation observed experimentally, i.e., stage I which has a steady decrease of the two parameters and stage II which shows a slow decrease, but with an enhanced fluctuation of the two parameters with increasing pulses of HIPIB generation.

  2. Determination of CdTe bulk carrier lifetime and interface recombination velocity of CdTe/MgCdTe double heterostructures grown by molecular beam epitaxy

    SciTech Connect

    Zhao, Xin-Hao; Campbell, Calli M.; DiNezza, Michael J.; Liu, Shi; Zhao, Yuan; Zhang, Yong-Hang

    2014-12-22

    The bulk Shockley-Read-Hall carrier lifetime of CdTe and interface recombination velocity at the CdTe/Mg{sub 0.24}Cd{sub 0.76}Te heterointerface are estimated to be around 0.5 μs and (4.7 ± 0.4) × 10{sup 2 }cm/s, respectively, using time-resolved photoluminescence (PL) measurements. Four CdTe/MgCdTe double heterostructures (DHs) with varying CdTe layer thicknesses were grown on nearly lattice-matched InSb (001) substrates using molecular beam epitaxy. The longest lifetime of 179 ns is observed in the DH with a 2 μm thick CdTe layer. It is also shown that the photon recycling effect has a strong influence on the bulk radiative lifetime, and the reabsorption process affects the measured PL spectrum shape and intensity.

  3. Electron irradiated liquid encapsulated Czochralski grown undoped gallium antimonide studied by positron lifetime spectroscopy and photoluminescence

    NASA Astrophysics Data System (ADS)

    Ma, S. K.; Lui, M. K.; Ling, C. C.; Fung, S.; Beling, C. D.; Li, K. F.; Cheah, K. W.; Gong, M.; Hang, H. S.; Weng, H. M.

    2004-09-01

    Electron irradiated undoped liquid encapsulated Czochralski (LEC) grown GaSb samples were studied by positron lifetime spectroscopy (PLS) and photoluminescence (PL). In addition to the 315 ps component reported in the previous studies, another defect with a lifetime of 280 ps was also identified in the present electron irradiated samples. The bulk lifetime of the GaSb material was found to be 258 ps. The VGa,280 ps and the VGa,315 ps defects were associated with two independent Ga vacancy related defects having different microstructures. The well known 777 meV PL signal (usually band A) was also observed in the electron irradiated undoped GaSb samples. The band A intensity decreases with increasing electron irradiation dosage and it disappears after the 300 °C annealing regardless of the irradiation dosage. The origin of the band A signal is also discussed.

  4. Fluorescence lifetime and anisotropy studies with liver alcohol dehydrogenase and its complexes.

    PubMed

    Eftink, M R; Hagaman, K A

    1986-10-21

    From measurements of the apparent phase and modulation fluorescence lifetime of liver alcohol dehydrogenase at multiple modulation frequencies (6, 18, and 30 MHz), the individual lifetimes and fractional intensities of Trp-314 and Trp-15 are calculated. Values of tau 314 = 3.6, tau 15 = 7.3, and f314 = 0.56, at 20 degrees C, are found. These values are in general agreement with values previously reported by Ross et al. [Ross, J.B.A., Schmidt, C.J., & Brand, L. (1981) Biochemistry 20, 4369] using pulse-decay methodology. In ternary complexes formed between the enzyme, NAD+ and either pyrazole or trifluoroethanol, the fluorescence lifetime of Trp-314 is found to be reduced, indicating that the binding of these ligands causes a dynamic quenching of this residue. The lifetime of Trp-314 is decreased more in the trifluoroethanol ternary complex than that with pyrazole. Also, the alkaline quenching transition of alcohol dehydrogenase is found to result in the selective, dynamic quenching of Trp-314. No change in the lifetimes of the two Trp residues is found upon selective removal of the active-site zinc atoms. From studies of the fluorescence anisotropy, r, of the enzyme as a function of added acrylamide (which selectively quenches the surface Trp-15 residue), the steady-state anisotropy of each residue is determined to be r314 = 0.26 and r15 = 0.21. In the ternary complexes the anisotropy of each residue increases slightly.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. DBD dyes as fluorescence lifetime probes to study conformational changes in proteins.

    PubMed

    Wawrzinek, Robert; Ziomkowska, Joanna; Heuveling, Johanna; Mertens, Monique; Herrmann, Andreas; Schneider, Erwin; Wessig, Pablo

    2013-12-16

    Previously, [1,3]dioxolo[4,5-f][1,3]benzodioxole (DBD)-based fluorophores used as highly sensitive fluorescence lifetime probes reporting on their microenvironmental polarity have been described. Now, a new generation of DBD dyes has been developed. Although they are still sensitive to polarity, in contrast to the former DBD dyes, they have extraordinary spectroscopic properties even in aqueous surroundings. They are characterized by long fluorescence lifetimes (10-20 ns), large Stokes shifts (≈100 nm), high photostabilities, and high quantum yields (>0.56). Here, the spectroscopic properties and synthesis of functionalized derivatives for labeling biological targets are described. Furthermore, thio-reactive maleimido derivatives of both DBD generations show strong intramolecular fluorescence quenching. This mechanism has been investigated and is found to undergo a photoelectron transfer (PET) process. After reaction with a thiol group, this fluorescence quenching is prevented, indicating successful bonding. Being sensitive to their environmental polarity, these compounds have been used as powerful fluorescence lifetime probes for the investigation of conformational changes in the maltose ATP-binding cassette transporter through fluorescence lifetime spectroscopy. The differing tendencies of the fluorescence lifetime change for both DBD dye generations promote their combination as a powerful toolkit for studying microenvironments in proteins.

  6. Alkali metal thermoelectric converter (AMTEC) electrode lifetime studies

    NASA Technical Reports Server (NTRS)

    Bankston, C. Perry; Williams, Roger M.; Jeffries-Nakamura, Barbara; Colle, Terry

    1987-01-01

    Experimental studies are being conducted at JPL to identify long life, high area power density electrodes for AMTEC. Power versus time measurements are being made in a demountable electrode test cell and, for longer term experiments, a self-contained recirculating cell. The experimental apparatus and procedures are described in detail. The results show that thin film molybdenum electrodes can be designed to produce power near 0.5 W/sq cm for over two hundred hours. Also, platinum/tungsten electrodes exhibit power densities that are stable near 0.5 W/sq cm. If the performance of these electrodes is verified for longer periods (thousands of hours), then practical AMTEC systems will be possible.

  7. Lifetime carcinogenicity study of 1- and 2-naphthylamine in dogs.

    PubMed Central

    Purchase, I. F.; Kalinowski, A. E.; Ishmael, J.; Wilson, J.; Gore, C. W.; Chart, I. S.

    1981-01-01

    Groups of male and female beagle dogs were given daily doses of 400 mg of various mixtures of naphthylamines for up to 109 months. Survivors were killed at 128 months. A variety of pathological conditions was diagnosed, but the only effect related to treatment was the induction of bladder neoplasms. All dogs which received pure 2-naphthylamine developed transitional-cell carcinomas of the bladder within 34 months. Two of 8 dogs receiving 6% 2-naphthylamine in 1-naphthylamine developed early carcinoma and 2/8 dogs receiving 0.5% 2-naphthylamine in 1-naphthylamine developed haemangioma of the bladder. Some of the dogs receiving 1-naphthylamine (total dose 950 g) and the controls had focal cystitis or hyperplasia, but no neoplasia of the bladder. These results confirm the carcinogenicity of 2-naphthylamine to dogs. No carcinogenic effect of 1-naphthylamine was observed, indicating that it is at least 200 times less potent as a carcinogen than 2-naphthylamine. The incidence of bladder cancer in dogs fed mixtures of both naphthylamines explains why previous experimental and epidemiological studies of impure 1-naphthylamine have revealed carcinogenicity. Images Fig. 1 Fig. 2 PMID:7326199

  8. Free volumes studies in Thymoquinone and Carvone β-cyclodextrin nanoparticles by positron annihilation lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Ferreira Marques, M. F.; Gordo, P. M.; Moreira da Silva, A.

    2013-06-01

    Positron annihilation lifetime spectroscopy is used to study free volume in β-cyclodextrin with the encapsulation of thymoquinone and S-carvone, in samples covering the guest to host fraction range from 1:0.1 to 1:1. The results clearly indicate the presence of long lifetime components related to Ps-formation. Although the behavior of the two guests is different, in both cases the results indicate the formation of 1:1 cyclodextrin inclusion compounds. Data show that the addition of carvone to β-cyclodextrin results in a decrease of the o-Ps lifetime corresponding to a reduction of the average radius of cavities from 2.41 Å to 2.29 Å, whereas the addition of thymoquine decreases the radius from 2.57 Å to 2.35 Å. In turn, the intensity varied from 20.55 to 19.20% and from 20.83 to 0.41%, respectively.

  9. Studies on Beam Formation in an Atomic Beam Source

    NASA Astrophysics Data System (ADS)

    Nass, A.; Stancari, M.; Steffens, E.

    2009-08-01

    Atomic beam sources (ABS) are widely used workhorses producing polarized atomic beams for polarized gas targets and polarized ion sources. Although they have been used for decades the understanding of the beam formation processes is crude. Models were used more or less successfully to describe the measured intensity and beam parameters. ABS's are also foreseen for future experiments, such as PAX [1]. An increase of intensity at a high polarization would be beneficial. A direct simulation Monte-Carlo method (DSMC) [2] was used to describe the beam formation of a hydrogen or deuterium beam in an ABS. For the first time a simulation of a supersonic gas expansion on a molecular level for this application was performed. Beam profile and Time-of-Flight measurements confirmed the simulation results. Furthermore a new method of beam formation was tested, the Carrier Jet method [3], based on an expanded beam surrounded by an over-expanded carrier jet.

  10. Acousto-Optic Beam Steering Study

    DTIC Science & Technology

    1994-08-01

    8217111 INK $ 1 1 illl iII Ill i, R L-TR-94-121 !1!1Il t 11I1!I!11! ilI, / Final Technical Report August 1994 ACOUSTO - OPTIC BEAM STEERING STUDY Harris...contractual obligations or notices on a specific document require that it be returned. For i ..........I ,, ACOUSTO - OPTIC BEAM STEERING STUDY H. W...4. TITLE AND SUBTITLE 5. FUNDING NUMBERS ACOUSTO - OPTIC BEAM STEERING STUDY C - F30602-91-C-0131 PE - 63215C 6. AUTHOR(S) PR - 1405 TA - 02 H. W

  11. Impact of walking on life expectancy and lifetime medical expenditure: the Ohsaki Cohort Study.

    PubMed

    Nagai, Masato; Kuriyama, Shinichi; Kakizaki, Masako; Ohmori-Matsuda, Kaori; Sone, Toshimasa; Hozawa, Atsushi; Kawado, Miyuki; Hashimoto, Shuji; Tsuji, Ichiro

    2011-01-01

    People who spend a longer time walking have lower demands for medical care. However, in view of their longer life expectancy, it is unclear whether their lifetime medical expenditure increases or decreases. The present study examined the association between time spent walking, life expectancy and lifetime medical expenditure. The authors followed up 27,738 participants aged 40-79 years and prospectively collected data on their medical expenditure and survival covering a 13-year-period. Participants were classified into those walking <1 and ≥1 h per day. The authors constructed life tables and estimated the life expectancy and lifetime medical expenditure from 40 years of age using estimate of multiadjusted mortality and medical expenditure using a Poisson regression model and linear regression model, respectively. Participants who walked ≥1 h per day have a longer life expectancy from 40 years of age than participants who walked <1 h per day. The multiadjusted life expectancy for those who walked ≥1 h per day was 44.81 years, significantly lower by 1.38 years in men (p=0.0073) in men and 57.78 years in women, non-significantly lower by 1.16 years in women (p=0.2351). In addition to their longer life expectancy, participants who walked ≥1 h per day required a lower lifetime medical expenditure from 40 years of age than participants who walked <1 h per day. The multiadjusted lifetime medical expenditure for those who walked ≥1 h per day was £99 423.6, significantly lower by 7.6% in men (p=0.0048) and £128 161.2, non-significantly lower by 2.7% in women (p=0.2559). Increased longevity resulting from a healthier lifestyle does not necessarily translate into an increased amount of medical expenditure throughout life. Encouraging people to walk may extend life expectancy and decrease lifetime medical expenditure, especially for men.

  12. Field of Study in College and Lifetime Earnings in the United States

    ERIC Educational Resources Information Center

    Kim, ChangHwan; Tamborini, Christopher R.; Sakamoto, Arthur

    2015-01-01

    Our understanding about the relationship between education and lifetime earnings often neglects differences by field of study. Utilizing data that match respondents in the Survey of Income and Program Participation to their longitudinal earnings records based on administrative tax information, we investigate the trajectories of annual earnings…

  13. The study of synthetic food dyes by positron annihilation lifetime spectroscopy.

    NASA Astrophysics Data System (ADS)

    Pivtsaev, A. A.; Razov, V. I.

    2015-06-01

    By method of positron annihilation lifetime spectroscopy (PALS), substances are food dyes were studied: E-102 (Tartrazine), E-124 (Ponso 4R), E 132 (Indigo carmine), E-133 (Brilliant Blue), E-151 (Black Shiny). They are examined for the presence of carcinogenic properties. The difference between dyes having explicit carcinogenic properties and mutagenic properties (non-explicit carcinogens) is established.

  14. The Effect of Clouds and Climate Change on the Lifetime of Methane: A Sensitivity Study

    NASA Astrophysics Data System (ADS)

    Dolan, K. E.; Stockwell, W. R.

    2013-12-01

    There have been many studies of the effects of climate change on air quality and atmospheric chemistry but relatively fewer on the potential effects of changes in the Earth's oxidizing capacity on climate change. The purpose of this study is to determine the effects of clouds on the lifetime of methane, through the oxidation of ozone, caused by the hydroxyl radical. Methane is one of the most important greenhouse gases with a high global warming potential. Numerical radiation transfer and chemical box models were used to assess the impact of clouds on the lifetime of methane based on IPCC scenarios. The chemical box model is based on the Regional Atmospheric Chemistry Mechanism, version 2 (RACM2) (Goliff et al., 2012). The average of aloft and ground conditions were used to derive the final result. This study found that averaged over the entire troposphere clouds increase actinic flux, increasing the photolysis rates of ozone. This increase in photolysis rates creates more hydroxyl radical, which in turn lowers the lifetime of methane. Higher altitude clouds further decrease this lifetime through their effect on actinic flux. In line with this result Mitchell and Ingram (1992) found that current climate models forecast an upward shift of high altitude clouds and a decreased cloud cover in the lower troposphere. This shift in cloud altitudes appears likely to provide a partial negative feedback loop to climate change by increasing global oxidizing capacity and therefore decreasing the global warming potential of methane and other greenhouse gases that react with the hydroxyl radical.

  15. The PACE study: lifetime and past-year prevalence of headache in Parma's adult general population.

    PubMed

    Taga, Arens; Russo, Marco; Manzoni, Gian Camillo; Torelli, Paola

    2017-02-17

    Headache is a widespread disorder and therefore it has a strong impact on quality of life. In the present work we focused on lifetime and past-year prevalence of headache in general and by gender, in a population-based sample in Parma. A total of 904 subjects representative of Parma's adult general population were interviewed face-to-face by a physician from the Parma Headache Centre, using a validated questionnaire. The lifetime prevalence of headache was 69.1%, i.e. 75.8% in women and 60.6% in men; the crude past-year prevalence of headache was 42.8%, i.e. 52.0% in women and 31.1% in men. Both lifetime and past-year prevalence rates were significantly higher in females than in males (odds ratio, respectively, 2.0 and 2.4). In our study, past-year prevalence decreased after age 50 in both genders. Most people suffer from one headache subtype. In over 80% of cases, headache starts before age 40 and therefore people were not very likely to develop headache after 50 years. The past-year and lifetime prevalence rate of headache in general that we found in our study falls within the lower range of values for headache prevalence in European countries. Further researches need to be set in the Italian epidemiological background.

  16. Neutron Lifetime Measurements

    NASA Astrophysics Data System (ADS)

    Nico, J. S.

    2006-11-01

    Precision measurements of neutron beta decay address basic questions in nuclear and particle physics, astrophysics, and cosmology. As the simplest semileptonic decay system, the free neutron plays an important role in understanding the physics of the weak interaction, and improving the precision of the neutron lifetime is fundamental to testing the validity of the theory. The neutron lifetime also directly affects the relative abundance of primordial helium in big bang nucleosynthesis. There are two distinct strategies for measuring the lifetime. Experiments using cold neutrons measure the absolute specific activity of a beam of neutrons by counting decay protons; experiments using confined, ultracold neutrons determine the lifetime by counting neutrons that remain after some elapsed time. The status of the recent lifetime measurements using both of these techniques is discussed.

  17. Neutron Lifetime Measurements

    SciTech Connect

    Nico, J. S.

    2006-11-17

    Precision measurements of neutron beta decay address basic questions in nuclear and particle physics, astrophysics, and cosmology. As the simplest semileptonic decay system, the free neutron plays an important role in understanding the physics of the weak interaction, and improving the precision of the neutron lifetime is fundamental to testing the validity of the theory. The neutron lifetime also directly affects the relative abundance of primordial helium in big bang nucleosynthesis. There are two distinct strategies for measuring the lifetime. Experiments using cold neutrons measure the absolute specific activity of a beam of neutrons by counting decay protons; experiments using confined, ultracold neutrons determine the lifetime by counting neutrons that remain after some elapsed time. The status of the recent lifetime measurements using both of these techniques is discussed.

  18. Studies of Beam Dynamics in Cooler Rings

    SciTech Connect

    Dietrich, J.; Stein, J.; Meshkov, I.; Sidorin, A.; Smirnov, A.

    2006-03-20

    This report describes the numerical simulation of the crystalline proton beam formation in COSY using BETACOOL code. The study includes the description of experimental results at NAP-M storage ring where the large reduction of the momentum spread was observed for first time. The present simulation shows that this behavior of proton beam can not be explained as ordered state of protons. The numerical simulation of crystalline proton beams was done for COSY parameters. The number of protons when the ordering state can be observed is limited by value 106 particles and momentum spread less then 10-6. Experimental results for the attempt to achieve of ordered state of proton beam for COSY is presented. This work is supported by RFBR grant no. 05-02-16320 and INTAS grant no. 03-54-5584.

  19. Field of Study in College and Lifetime Earnings in the United States

    PubMed Central

    Kim, ChangHwan; Tamborini, Christopher R.; Sakamoto, Arthur

    2016-01-01

    Our understanding about the relationship between education and lifetime earnings often neglects differences by field of study. Utilizing data that matches respondents in the Survey of Income and Program Participation to their longitudinal earnings records based on administrative tax information, we investigate the trajectories of annual earnings following the same individuals over 20 years and then estimate the long-term effects of field of study on earnings for U.S. men and women. Our results provide new evidence revealing large lifetime earnings gaps across field of study. We show important differences in individuals’ earnings trajectories across the different stages of the work-life by field of study. In addition, the gaps in 40-year (i.e., ages 20 to 59) median lifetime earnings among college graduates by field of study are larger, in many instances, than the median gap between high school graduates and college graduates overall. Significant variation is also found among graduate degree holders. Our results uncover important similarities and differences between men and women with regard to the long-term earnings differentials associated with field of study. In general, these findings underscore field of study as a critical dimension of horizontal stratification in educational attainment. Other implications of the empirical findings are also discussed. PMID:28042177

  20. Experimental study using Touschek lifetime as machine status flag in SSRF

    NASA Astrophysics Data System (ADS)

    Chen, Zhi-Chu; Leng, Yong-Bin; Yuan, Ren-Xian; Yan, Ying-Bing; Yu, Lu-Yang

    2014-07-01

    The stabilities of the beam and machine have almost the highest priority in a modern light source. Although a lot of machine parameters could be used to represent the beam quality, there is no single parameter that could indicate the global information for the machine operators and accelerator physicists. For the last few years, a new parameter has been studied as a beam quality flag in the Shanghai Synchrotron Radiation Facility (SSRF). Calculations, simulations and detailed analysis of the real-time data from the storage ring have been made and the interesting results have confirmed its feasibility.

  1. Analytical and experimental investigation of the feasibility of accelerated lifetime testing of materials exposed to an atomic oxygen beam

    NASA Technical Reports Server (NTRS)

    Albridge, Royal; Barnes, Alan; Tolk, Norman

    1993-01-01

    The interaction of atomic particles with surfaces is of both scientific and technological interest. Past work emphasizes the measurement of high-energy sputtering yields. Very little work utilized low-energy beams for which chemical and electronic effects can be important. Even less work has been carried out using well-defined low-energy projectiles. The use of low-energy, reactive projectiles permits one to investigate surface processes that have not been well characterized. As the energy of the projectile decreases, the collisional cascades and spikes, that are common for high-energy projectiles, become less important, and chemical and electronic effects can play a significant role. Aspects of particle-surface interactions are of concern in several areas of technology. For example, the erosion, desorption, and glow of surfaces of spacecraft in orbit are important in the arena of space technology. The materials studied under this contract are of possible use on the exterior portions of the power generation system of Space Station Freedom. Under the original designs, Space Station Freedom's power generation system would generate potential differences on the surface as high as 200 volts. Ions in the plasma that often surround orbiting vehicles would be accelerated by these potentials leading to bombardment and erosion of the exposed surfaces. The major constituent of the atmosphere, approximately 90 percent, in the low earth orbit region is atomic oxygen. Since atomic oxygen is extremely reactive with most materials, chemical effects can arise in addition to the physical sputtering caused by the acceleration of the oxygen ions. Furthermore, the incident oxygen ions can remain embedded in the exposed surfaces, altering the chemical composition of the surfaces. Since the effective binding energy of a chemically altered surface can be quite different from that of the pure substrate, the sputtering yield of a chemically altered surface is usually different also. The low

  2. Minority Carrier Lifetime and Photoluminescence Studies of Antimony-Based Superlattices

    NASA Technical Reports Server (NTRS)

    Hoglund, Linda; Soibel, Alexander; Ting, David Z.; Khoshakhlagh, Arezou; Hill, Cory J.; Gunapala, Sarath D.

    2012-01-01

    In this paper, we have used the OMR technique to study the minority carrier lifetimes in three InAs/GaSb-photoluminescence (PL) structures with different number of periods in the absorber: 300, 400 and 600 periods respectively. The feasibility of using a visible 643 nm laser source with short penetration depth for lifetime measurements was studied by comparing the achieved results to measurements performed on the same samples with a 1550 nm IR laser source, which penetrates much deeper into the sample. Despite the differences in excitation wavelengths and penetration depths, the results from both measurements were very similar. This indicates that the diffusion length is long enough to facilitate a homogeneous distribution of excess carriers in the material.

  3. Minority Carrier Lifetime and Photoluminescence Studies of Antimony-Based Superlattices

    NASA Technical Reports Server (NTRS)

    Hoglund, Linda; Soibel, Alexander; Ting, David Z.; Khoshakhlagh, Arezou; Hill, Cory J.; Gunapala, Sarath D.

    2012-01-01

    In this paper, we have used the OMR technique to study the minority carrier lifetimes in three InAs/GaSb-photoluminescence (PL) structures with different number of periods in the absorber: 300, 400 and 600 periods respectively. The feasibility of using a visible 643 nm laser source with short penetration depth for lifetime measurements was studied by comparing the achieved results to measurements performed on the same samples with a 1550 nm IR laser source, which penetrates much deeper into the sample. Despite the differences in excitation wavelengths and penetration depths, the results from both measurements were very similar. This indicates that the diffusion length is long enough to facilitate a homogeneous distribution of excess carriers in the material.

  4. Effect of free-carrier concentration and optical injection on carrier lifetimes in undoped and iodine doped CdMgTe/CdSeTe double heterostructures grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Sohal, S.; Edirisooriya, M.; Ogedengbe, O. S.; Petersen, J. E.; Swartz, C. H.; LeBlanc, E. G.; Myers, T. H.; Li, J. V.; Holtz, M.

    2016-12-01

    Time-resolved and time integrated photoluminescence (PL) studies are reported for undoped and doped CdMgTe/CdSeTe double heterostructures (DHs) grown by molecular beam epitaxy. Undoped DHs are studied with absorber layer thickness varying from 0.5 to 2.5 µm. The n-type free-carrier concentration is varied ~7  ×  1015, 8.4  ×  1016, and 8.4  ×  1017 cm-3 using iodine as a dopant in different absorber layer thicknesses (0.25-2.0 µm). Optical injection is varied from 1  ×  1010 to 3  ×  1011 photons/pulse/cm2, corresponding to the initial injection of photo-carriers up to ~8  ×  1015 cm-3, to examine the effects of excess carrier concentration on the PL lifetimes. Undoped DHs exhibit an initial rapid decay followed by a slower dependence with carrier lifetimes up to ~485 ns. The dependence of carrier lifetimes on the thickness of the absorber layers (0.5-2.5 µm) suggests interface recombination velocities ({{v}\\operatorname{int}}~ ) ~ 1288 and 238 cm s-1 in the initial and later decay times, respectively, corresponding to high and low photo-carrier concentrations. The Shockley-Read-Hall model is used to describe the results in which variations are observed in {{v}\\operatorname{int}}~ for undoped DHs. The lifetimes of doped DHs show a consistent trend with thickness. The {{v}\\operatorname{int}}~ ~ 80-200 cm s-1 is estimated for doping n ~ 7  ×  1015 cm-3 and 240-410 cm s-1 for n ~ 8.4  ×  1016 cm-3. The observed decrease in carrier lifetimes with increasing n is consistent with growing importance of the radiative recombination rate due to the excess carrier concentration. The effect of carrier concentration on the PL spectrum is also discussed.

  5. Gut Microbiome Associates With Lifetime Cardiovascular Disease Risk Profile Among Bogalusa Heart Study Participants.

    PubMed

    Kelly, Tanika N; Bazzano, Lydia A; Ajami, Nadim J; He, Hua; Zhao, Jinying; Petrosino, Joseph F; Correa, Adolfo; He, Jiang

    2016-09-30

    Few studies have systematically assessed the influence of gut microbiota on cardiovascular disease (CVD) risk. To examine the association between gut microbiota and lifetime CVD risk profile among 55 Bogalusa Heart Study participants with the highest and 57 with the lowest lifetime burdens of CVD risk factors. 16S ribosomal RNA sequencing was conducted on microbial DNA extracted from stool samples of the Bogalusa Heart Study participants. α Diversity, including measures of richness and evenness, and individual genera were tested for associations with lifetime CVD risk profile. Multivariable regression techniques were used to adjust for age, sex, and race (model 1), along with body mass index (model 2) and both body mass index and diet (model 3). In model 1, odds ratios (95% confidence intervals) for each SD increase in richness, measured by the number of observed operational taxonomic units, Chao 1 index, and abundance-based coverage estimator, were 0.62 (0.39-0.99), 0.61 (0.38-0.98), and 0.63 (0.39-0.99), respectively. Associations were consistent in models 2 and 3. Four genera were enriched among those with high versus low CVD risk profile in all models. Model 1 P values were 2.12×10(-3), 7.95×10(-5), 4.39×10(-4), and 1.51×10(-4) for Prevotella 2, Prevotella 7, Tyzzerella, and Tyzzerella 4, respectively. Two genera were depleted among those with high versus low CVD risk profile in all models. Model 1 P values were 2.96×10(-6) and 1.82×10(-4) for Alloprevotella and Catenibacterium, respectively. The current study identified associations of overall microbial richness and 6 microbial genera with lifetime CVD risk. © 2016 American Heart Association, Inc.

  6. UCNtau: Study of Lifetime Measurement in a Magneto-Gravitational Trap

    SciTech Connect

    Saunders, Alexander; Salvat, D.; Adamek, E.; Bowman, D.; Clayton, S.; Cude, C.; Fox, W.; Hogan, G.; Hickerson, K.; Holley, A. T.; Liu, C.-Y.; Makela, M.; Manus, G.; Morris, C.; Penttila, S.; Ramsey, J.; Sawtelle, S.; Solberg, K.; Vanderwerp, J.; VornDick, B.; Walstrom, P.; Wang, Z.; Young, A. R.

    2014-01-01

    The UCNtau project is intended to develop a new measurement of the neutron lifetime using ultra-cold neutrons (UCNs) stored in a magneto-gravitational trap. In this article, we will describe the development of the experiment so far, including the trap itself, the UCN transport and monitoring system, the neutron detection methods, and the Monte Carlo simulations that have been used to model these elements. Finally, we will describe the first systematic effects that we plan to study using this apparatus.

  7. Lifetime abuse and perceived social support among the elderly: a study from seven European countries.

    PubMed

    Eslami, Bahareh; Di Rosa, Mirko; Barros, Henrique; Stankunas, Mindaugas; Torres-Gonzalez, Francisco; Ioannidi-Kapolou, Elisabeth; Lindert, Jutta; Melchiorre, Maria Gabriella

    2017-04-11

    Being a victim of abuse during one's life course may affect social relations in later life. The aims of this study were to: (i) examine the association between lifetime abuse and perceived social support and (ii) identify correlates of perceived social support among older persons living in seven European countries. A sample of 4467 women and men aged 60-84 years living in Germany, Greece, Italy, Lithuania, Portugal, Spain and Sweden was collected through a cross-sectional population-based study. Abuse (psychological, physical, sexual, financial and injury) was assessed through interviews or interviews/self-response questionnaire based on the Conflict Tactics Scale-2 and the UK study on elder abuse. Perceived social support was assessed by the Multidimensional Scale of Perceived Social Support. Victims of lifetime abuse perceived poorer social support in later life. Multivariate analyses showed that high levels of perceived social support were associated with being from Greece and Lithuania (compared to Germany), being female, not living alone, consuming alcohol and physical activity. Poorer perceived social support was associated with being from Portugal, being old, having social benefits as the main source of income, experiencing financial strain and being exposed to lifetime psychological abuse and injuries. Our findings showed that exposure to psychological abuse and injuries across the lifespan were associated with low levels of perceived social support, emphasizing the importance of detection and appropriate treatment of victims of abuse during their life course. Future research should focus on coping strategies buffering the negative effects of abuse on social relationships.

  8. The Association of Early Substance Use with Lifetime/Past Year Contraction of Sexually Transmitted Diseases: A National Study

    ERIC Educational Resources Information Center

    Merianos, Ashley L.; Rosen, Brittany L.; King, Keith A.; Vidourek, Rebecca A.; Fehr, Sara K.

    2015-01-01

    The study purpose is to examine the impact of early substance use on lifetime and past year contraction of sexually transmitted diseases (STDs), including chlamydia, gonorrhea, herpes, and syphilis. A secondary analysis of the 2012 National Survey on Drug Use and Health (N = 52,529) was conducted to determine if lifetime or past year STD…

  9. The Association of Early Substance Use with Lifetime/Past Year Contraction of Sexually Transmitted Diseases: A National Study

    ERIC Educational Resources Information Center

    Merianos, Ashley L.; Rosen, Brittany L.; King, Keith A.; Vidourek, Rebecca A.; Fehr, Sara K.

    2015-01-01

    The study purpose is to examine the impact of early substance use on lifetime and past year contraction of sexually transmitted diseases (STDs), including chlamydia, gonorrhea, herpes, and syphilis. A secondary analysis of the 2012 National Survey on Drug Use and Health (N = 52,529) was conducted to determine if lifetime or past year STD…

  10. Cardiovascular lifetime risk predicts incidence of coronary calcification in individuals with low short-term risk: the Dallas Heart Study.

    PubMed

    Paixao, Andre R M; Ayers, Colby R; Rohatgi, Anand; Das, Sandeep R; de Lemos, James A; Khera, Amit; Lloyd-Jones, Donald; Berry, Jarett D

    2014-11-25

    The absence of coronary artery calcium (CAC) in middle age is associated with very low short-term risk for coronary events. However, the long-term implications of a CAC score of 0 are uncertain, particularly among individuals with high cardiovascular lifetime risk. We sought to characterize the association between predicted lifetime risk and incident CAC among individuals with low short-term risk. We included 754 Dallas Heart Study participants with serial CAC scans (6.9 years apart) and both low short-term risk and baseline CAC=0. Lifetime risk for cardiovascular disease was estimated according to risk factor burden. Among this group, 365 individuals (48.4%) were at low lifetime risk and 389 (51.6%) at high lifetime risk. High lifetime risk was associated with higher annualized CAC incidence (4.2% versus 2.7%; P < 0.001). Similarly, mean follow-up CAC scores were higher among participants with high lifetime risk (7.8 versus 2.4 Agatston units). After adjustment for age, sex, and race, high lifetime risk remained independently associated with incident CAC (OR 1.60; 95% CI 1.12 to 2.27; P=0.01). When assessing risk factor burden at the follow-up visit, 66.7% of CAC incidence observed in the low lifetime risk group occurred among individuals reclassified to a higher short- or long-term risk category. Among individuals with low short-term risk and CAC scores of 0, high lifetime risk is associated with a higher incidence of CAC. These findings highlight the importance of lifetime risk even among individuals with very low short-term risk. © 2014 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  11. Cardiovascular Lifetime Risk Predicts Incidence of Coronary Calcification in Individuals With Low Short‐Term Risk: The Dallas Heart Study

    PubMed Central

    Paixao, Andre R. M.; Ayers, Colby R.; Rohatgi, Anand; Das, Sandeep R.; de Lemos, James A.; Khera, Amit; Lloyd‐Jones, Donald; Berry, Jarett D.

    2014-01-01

    Background The absence of coronary artery calcium (CAC) in middle age is associated with very low short‐term risk for coronary events. However, the long‐term implications of a CAC score of 0 are uncertain, particularly among individuals with high cardiovascular lifetime risk. We sought to characterize the association between predicted lifetime risk and incident CAC among individuals with low short‐term risk. Methods and Results We included 754 Dallas Heart Study participants with serial CAC scans (6.9 years apart) and both low short‐term risk and baseline CAC=0. Lifetime risk for cardiovascular disease was estimated according to risk factor burden. Among this group, 365 individuals (48.4%) were at low lifetime risk and 389 (51.6%) at high lifetime risk. High lifetime risk was associated with higher annualized CAC incidence (4.2% versus 2.7%; P < 0.001). Similarly, mean follow‐up CAC scores were higher among participants with high lifetime risk (7.8 versus 2.4 Agatston units). After adjustment for age, sex, and race, high lifetime risk remained independently associated with incident CAC (OR 1.60; 95% CI 1.12 to 2.27; P=0.01). When assessing risk factor burden at the follow‐up visit, 66.7% of CAC incidence observed in the low lifetime risk group occurred among individuals reclassified to a higher short‐ or long‐term risk category. Conclusion Among individuals with low short‐term risk and CAC scores of 0, high lifetime risk is associated with a higher incidence of CAC. These findings highlight the importance of lifetime risk even among individuals with very low short‐term risk. PMID:25424574

  12. Left ventricular hypertrophy, aortic wall thickness, and lifetime predicted risk of cardiovascular disease:the Dallas Heart Study.

    PubMed

    Gupta, Sachin; Berry, Jarett D; Ayers, Colby R; Peshock, Ronald M; Khera, Amit; de Lemos, James A; Patel, Parag C; Markham, David W; Drazner, Mark H

    2010-06-01

    To examine whether individuals with low short-term risk of coronary heart disease but high lifetime predicted risk of cardiovascular disease (CVD) have greater prevalence of left ventricular (LV) hypertrophy and increased aortic wall thickness (AWT) than those with low short-term and low lifetime risk. Lifetime risk prediction can be used for stratifying individuals younger than 50 years of age into 2 groups: low short-term/high lifetime and low short-term/low lifetime predicted risk of CVD. Individuals with low short-term/high lifetime risk have a greater burden of subclinical atherosclerosis as measured by coronary artery calcium and carotid intima-media thickness. However, >75% of individuals with low short-term/high lifetime risk do not have detectable coronary artery calcium, suggesting the presence of alternative subclinical abnormalities. We stratified 1,804 Dallas Heart Study subjects between the ages of 30 and 50 years who had cardiac magnetic resonance into 3 groups: low short-term (<10% 10-year risk of coronary heart disease)/low lifetime predicted risk (<39% lifetime risk of CVD), low short-term (<10%)/high lifetime risk (> or =39%), and high short-term risk (> or =10%, prevalent diabetes, or previous stroke, or myocardial infarction). In those with low short-term risk, we compared measures of LV hypertrophy and AWT between those with low versus high lifetime risk. Subjects with low short-term/high lifetime risk compared with those with low short-term/low lifetime risk had increased LV mass (men: 95 +/- 17 g/m(2) vs. 90 +/- 12 g/m(2) and women: 75 +/- 14 g/m(2) vs. 71 +/- 10 g/m(2), respectively; p < 0.001 for both). LV concentricity (mass/volume), wall thickness, and AWT were also significantly greater in those with high lifetime risk in this comparison (p < 0.001 for all), but LV end-diastolic volume was not (p > 0.3). These associations persisted among participants without detectable coronary artery calcium. Among individuals 30 to 50 years of age

  13. A case-control study of lifetime light intensity physical activity and breast cancer risk.

    PubMed

    Kobayashi, Lindsay C; Janssen, Ian; Richardson, Harriet; Lai, Agnes S; Spinelli, John J; Aronson, Kristan J

    2014-01-01

    Physical activity reduces breast cancer risk, although most evidence is for activity in the moderate-to-vigorous intensity range. The effect of light intensity physical activity (LIPA) is unknown. We aimed to determine the association between self-reported lifetime LIPA and pre- and post-menopausal breast cancer risk. Our secondary objective was to analyze risk stratified by estrogen and progesterone tumor receptor status. Data were from a case-control study of 1,110 incident breast cancer cases (388 pre-menopausal; 722 post-menopausal) and 1,172 controls (442 pre-menopausal; 730 post-menopausal) recruited at two Canadian sites. Lifetime leisure-time, household, and occupational physical activity and covariates were assessed by questionnaire. Mean minutes per day of LIPA for each of the age periods 12-17, 18-34, 35-49, ≥50, and the total lifetime were calculated. Odds ratios were calculated using unconditional logistic regression for overall breast cancer risk and using polytomous logistic regression for estrogen receptor (ER)/progesterone receptor (PR)-defined tumor subtypes and were adjusted for moderate-to-vigorous physical activity and other confounders. LIPA was not associated with breast cancer risk at any age period across the life course: odds ratio (OR) = 0.81; 95 % CI 0.53-1.24 for pre-menopausal women and OR = 0.87; 95 % CI 0.64-1.19 for post-menopausal women in the highest vs. lowest categories of total lifetime LIPA. No heterogeneity in risk by ER/PR tumor status was observed. Our results suggest that light intensity physical activity is not associated with breast cancer risk reduction. This finding is important for physical activity recommendations for breast cancer prevention.

  14. Studies of electron spin lifetimes in InGaAs:Al quantum wells

    NASA Astrophysics Data System (ADS)

    Ali, T.; Khan, I.; Yasar, M.; Petrou, A.; Li, C.; Hanbicki, A.; Kioseoglou, G.; Jonker, B.

    2009-03-01

    We have carried out optical pumping, Hanle and longitudinal Hanle studies of InGaAs:Al/GaAs single quantum wells. The circular polarization at zero magnetic field has a maximum around 50 K indicating that at low temperatures the recombination is associated with a bound electron. The measured spin lifetimes at low temperatures are an order of magnitude longer than those measured in reference GaAs/AlGaAs quantum wells. This is attributed to the suppression of the Dyakonov-Perel spin relaxation mechanism in this bound system. As the temperature is increased from 5 to 50 K the spin lifetimes decrease and become comparable to the lifetimes of the reference sample. In the longitudinal Hanle geometry the circular polarization increases with magnetic field and reaches a maximum at B 1.5 tesla. Beyond 1.5 tesla the circular polarization decreases. A series of polarization oscillations superimposed on the decreasing background with a periodicity of approximately 1 tesla is observed. These oscillations are tentatively attributed to the variations in the magnetic flux through the bound electron orbit. Work at SUNY was supported by ONR and NSF

  15. Thermal stability of nanocrystalline Cu studied by positron annihilation lifetime spectroscopy and X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Zhou, Kai; Li, Hui; Pang, JinBiao; Wang, Zhu

    2012-06-01

    Thermal stability of nanocrystalline Cu prepared by compacting nanoparticles (mean grain size about 50 nm) under high pressure has been studied by means of positron annihilation lifetime spectroscopy and X-ray diffraction. A gradual increase of mean grain size in the sample is observed with an increase in ageing time at 180°C, indicating an increase of volume fraction of the ordered regions. Furthermore, during the ageing, the increase in average size of the vacancy clusters in grain boundaries is confirmed by the positron lifetime results. The recrystallization is observed at the temperature of about 180°C, and becomes significant above 650°C. Three annealing stages, which are at the intervals 180-400°C, 400-650°C and 650-900°C have been characterized by positron average lifetime. The average volume of the defects almost remains constant in the interval 400-650°C but becomes considerably smaller in the interval 650-900°C.

  16. Electron beam, laser beam and plasma arc welding studies

    NASA Technical Reports Server (NTRS)

    Banas, C. M.

    1974-01-01

    This program was undertaken as an initial step in establishing an evaluation framework which would permit a priori selection of advanced welding processes for specific applications. To this end, a direct comparison of laser beam, electron beam and arc welding of Ti-6Al-4V alloy was undertaken. Ti-6Al-4V was selected for use in view of its established welding characteristics and its importance in aerospace applications.

  17. Gamma Putty dosimetric studies in electron beam

    PubMed Central

    Gloi, Aime M.

    2016-01-01

    Traditionally, lead has been used for field shaping in megavoltage electron beams in radiation therapy. In this study, we analyze the dosimetric parameters of a nontoxic, high atomic number (Z = 83), bismuth-loaded material called Gamma Putty that is malleable and can be easily molded to any desired shape. First, we placed an ionization chamber at different depths in a solid water phantom under a Gamma Putty shield of thickness (t = 0, 3, 5, 10, 15, 20, and 25 mm, respectively) and measured the ionizing radiation on the central axis (CAX) for electron beam ranging in energies from 6 to 20 MeV. Next, we investigated the relationship between the relative ionization (RI) measured at a fixed depth for several Gamma Putty shield at different cutout diameters ranging from 2 to 5 cm for various beam energies and derived an exponential fitting equation for clinical purposes. The dose profiles along the CAX show that bremsstrahlung dominates for Gamma Putty thickness >15 mm. For high-energy beams (12–20 MeV) and all Gamma Putty thicknesses up to 25 mm, RI below 5% could not be achieved due to the strong bremsstrahlung component. However, Gamma Putty is a very suitable material for reducing the transmission factor below 5% and protecting underlying normal tissues for low-energy electron beams (6–9 MeV). PMID:27651563

  18. Positron annihilation lifetime spectroscopy at a superconducting electron accelerator

    NASA Astrophysics Data System (ADS)

    Wagner, A.; Anwand, W.; Attallah, A. G.; Dornberg, G.; Elsayed, M.; Enke, D.; Hussein, A. E. M.; Krause-Rehberg, R.; Liedke, M. O.; Potzger, K.; Trinh, T. T.

    2017-01-01

    The Helmholtz-Zentrum Dresden-Rossendorf operates a superconducting linear accelerator for electrons with energies up to 35 MeV and average beam currents up to 1.6 mA. The electron beam is employed for production of several secondary beams including X-rays from bremsstrahlung production, neutrons, and positrons. The secondary positron beam after moderation feeds the Monoenergetic Positron Source (MePS) where positron annihilation lifetime (PALS) and positron annihilation Doppler-broadening experiments in materials science are performed in parallel. The adjustable repetition rate of the continuous-wave electron beams allows matching of the pulse separation to the positron lifetime in the sample under study. The energy of the positron beam can be set between 0.5 keV and 20 keV to perform depth resolved defect spectroscopy and porosity studies especially for thin films.

  19. Positron lifetime studies on 8 MeV electron-irradiated n-type 6H silicon carbide

    NASA Astrophysics Data System (ADS)

    Lam, C. H.; Lam, T. W.; Ling, C. C.; Fung, S.; Beling, C. D.; De-Sheng, Hang; Huimin, Weng

    2004-11-01

    The positron lifetime technique was employed to study vacancy-type defects in 8 MeV electron-irradiated n-type 6H silicon carbide. A long-lifetime component having a characteristic lifetime of 223-232 ps was observed in the irradiated sample and was attributed to the VCVSi divacancy. Other positron traps, which dominated at low temperatures, were observed to compete with the VCVSi for trapping positrons. A positron trapping model involving a positron shallow trap, a negatively charged monovacancy and the VCVSi divacancy was found to give a good description of the temperature-dependent positron lifetime data of the 1200 °C annealed sample. The identity of the monovacancy could not be unambiguously determined, but its lifetime was found to be in the range 160-172 ps.

  20. Positron beam studies of saponite film prepared by precipitation method

    NASA Astrophysics Data System (ADS)

    Numata, K.; Sato, K.; Fujimoto, K.; Ito, K.

    2017-01-01

    Micrometer-sized saponite particles were isolated by means of gravitational sedimentation method applying Stokes’ law. The sample prepared with this method was film-like state with a thickness of ~ 30 μm and was semitransparent, indicating that the particles are homogeneously stacked all together. Positron lifetime spectroscopy using a slow positron beam yielded two components for ortho-positronium with lifetimes of 1.5 ns and 8.4 ns with the respective relative intensities of 13 % and 10 %. The results suggest that the self-assembly of the larger particles toward structural densification is suppressed for the present film in comparison with the smaller nanoparticles.

  1. Beamed-Energy Propulsion (BEP) Study

    NASA Technical Reports Server (NTRS)

    George, Patrick; Beach, Raymond

    2012-01-01

    The scope of this study was to (1) review and analyze the state-of-art in beamed-energy propulsion (BEP) by identifying potential game-changing applications, (2) formulate a roadmap of technology development, and (3) identify key near-term technology demonstrations to rapidly advance elements of BEP technology to Technology Readiness Level (TRL) 6. The two major areas of interest were launching payloads and space propulsion. More generally, the study was requested and structured to address basic mission feasibility. The attraction of beamed-energy propulsion (BEP) is the potential for high specific impulse while removing the power-generation mass. The rapid advancements in high-energy beamed-power systems and optics over the past 20 years warranted a fresh look at the technology. For launching payloads, the study concluded that using BEP to propel vehicles into space is technically feasible if a commitment to develop new technologies and large investments can be made over long periods of time. From a commercial competitive standpoint, if an advantage of beamed energy for Earth-to-orbit (ETO) is to be found, it will rest with smaller, frequently launched payloads. For space propulsion, the study concluded that using beamed energy to propel vehicles from low Earth orbit to geosynchronous Earth orbit (LEO-GEO) and into deep space is definitely feasible and showed distinct advantages and greater potential over current propulsion technologies. However, this conclusion also assumes that upfront infrastructure investments and commitments to critical technologies will be made over long periods of time. The chief issue, similar to that for payloads, is high infrastructure costs.

  2. In-beam measurements of sub-nanosecond nuclear lifetimes with a mixed array of HPGe and LaBr3:Ce detectors

    NASA Astrophysics Data System (ADS)

    Mărginean, N.; Balabanski, D. L.; Bucurescu, D.; Lalkovski, S.; Atanasova, L.; Căta-Danil, G.; Căta-Danil, I.; Daugas, J. M.; Deleanu, D.; Detistov, P.; Deyanova, G.; Filipescu, D.; Georgiev, G.; Ghiţă, D.; Gladnishki, K. A.; Lozeva, R.; Glodariu, T.; Ivaşcu, M.; Kisyov, S.; Mihai, C.; Mărginean, R.; Negret, A.; Pascu, S.; Radulov, D.; Sava, T.; Stroe, L.; Suliman, G.; Zamfir, N. V.

    2010-12-01

    A fast-timing method to determine lifetimes of nuclear states in the sub-nanosecond domain is presented. It is based on in-beam measurements of triple-gamma coincidences in heavy-ion fusion-evaporation reactions, performed with an array of HPGe and LaBr3:Ce detectors. The high-energy resolution HPGe detectors are used to define de-exciting cascades, while the fast LaBr3:Ce detectors are used to determine the decay time spectra of selected levels fed by these cascades. A special method to treat the time information of an array of fast detectors is employed in order to fully use the efficiency of the array. Two measurements are presented to illustrate the method: a re-determination of the known half-life ensuremath T_{1/2}=0.7 ns of the ensuremath E_x=205 keV, ensuremath J^{π}=7/2^+ level in 107Cd (test experiment), and the determination of a half-life ensuremath T_{1/2}=47 ps for the ensuremath E_x=367 keV, ensuremath J^{π}=3/2^+ state of 199Tl.

  3. Photo-degradation of Lexan polycarbonate studied using positron lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Hareesh, K.; Pandey, A. K.; Meghala, D.; Ranganathaiah, C.; Sanjeev, Ganesh

    2013-02-01

    The free volume properties of pristine and UV irradiated Lexan polycarbonate have been investigated using Positron Lifetime Spectroscopy (PLS). The decrease in o-Ps life time and free volume size of irradiated sample is attributed to free volume modification and formation of more stable free radicals. These free radicals are formed due to the breakage of C-O bonds in Lexan polycarbonate after irradiation. This is also supported by the decrease in the intensity of C-O bond after exposure to UV-radiation as studied from Fourier Transform Infrared (FTIR) spectroscopy and it also shows that benzene ring does not undergo any changes after irradiation.

  4. Energies and lifetimes of magnons in complex ferromagnets: a first-principle study of Heusler alloys.

    PubMed

    Buczek, Paweł; Ernst, Arthur; Bruno, Patrick; Sandratskii, Leonid M

    2009-06-19

    The energies and lifetimes of magnons in several Mn-based Heusler alloys are studied using linear response density functional theory. The number of the spin wave branches in Co(2)MnSi corresponds to the number of its magnetic sublattices in contrast with the NiMnSb case in which the induced Ni sublattice cannot support optical magnons. The half-metallicity of these systems results in long-living acoustic spin waves. The example of non-half-metallic Cu(2)MnAl shows that the hybridization with Stoner continuum leads not only to the damping of magnons but also to a renormalization of their energies.

  5. Beam-Beam Study on the Upgrade of Beijing Electron Positron Collider

    SciTech Connect

    Wang, S.; Cai, Y.; /SLAC

    2006-02-10

    It is an important issue to study the beam-beam interaction in the design and performance of such a high luminosity collider as BEPCII, the upgrade of Beijing Electron Positron Collider. The weak-strong simulation is generally used during the design of a collider. For performance a large scale tune scan, the weak-strong simulation studies on beam-beam interaction were done, and the geometry effects were taken into account. The strong-strong simulation studies were done for investigating the luminosity goal and the dependence of the luminosity on the beam parameters.

  6. Studies on the Use of Liquid Surface Passivation for Lifetime Measurements on Good-Quality Silicon Wafers

    SciTech Connect

    Devayajanam, S.; Rupnowski, P.; Shet, S.; Sopori, B. L.; Ravindra, N. M.; Caskey, D.; Chang, J.; Covington, J.

    2011-01-01

    We evaluated several liquid passivants, viz. solutions of iodine ethanol (IE), quinhydrone methanol (QHM), and potassium cyanide (KCN), for measuring minority-carrier lifetime. Lifetime was measured by the WCT-100 (Sinton Instruments) and WT-2000 (Semilab). Our results show that both IE and QHM passivation are reliable mechanisms. We also find that the KCN solution is moderately passivating on oxidized surfaces, but is only minimally effective on bare Si surfaces. This paper presents details of our studies. In particular, the effect of illumination on IE-passivated surfaces and possible reasons for variations in lifetime measurement are discussed.

  7. Studies on Mathematical Models of Wet Adhesion and Lifetime Prediction of Organic Coating/Steel by Grey System Theory

    PubMed Central

    Meng, Fandi; Liu, Ying; Liu, Li; Li, Ying; Wang, Fuhui

    2017-01-01

    A rapid degradation of wet adhesion is the key factor controlling coating lifetime, for the organic coatings under marine hydrostatic pressure. The mathematical models of wet adhesion have been studied by Grey System Theory (GST). Grey models (GM) (1, 1) of epoxy varnish (EV) coating/steel and epoxy glass flake (EGF) coating/steel have been established, and a lifetime prediction formula has been proposed on the basis of these models. The precision assessments indicate that the established models are accurate, and the prediction formula is capable of making precise lifetime forecasting of the coatings. PMID:28773073

  8. The study of lifetime of polymer and composite bone joint screws under cyclical loads and in vitro conditions.

    PubMed

    Jan, Chłopek; Grzegorz, Kmita

    2005-11-01

    The "strain-life time" method has been adapted for life-time prediction of polymer and composite bone joint screws. Mechanical and fatigue properties of screws made of biostable (polysulfone), biosorbable (poly(lactide-co-glycolide) and short carbon fibre reinforced polymer composite materials have been examined in this study. The lifetime predictions under in vitro conditions were calculated for polymer and composite implants. The forecasting of joint screws stability under conditions close to natural body environment is shown to be feasible based on equations describing lifetime of the examined joint screws.

  9. Beam structure and transverse emittance studies of high-energy ion beams

    NASA Astrophysics Data System (ADS)

    Saadatmand, K.; Johnson, K. F.; Schneider, J. D.

    1991-05-01

    A visual diagnostic technique was developed to monitor and study ion beam structure shape and size along a transport line. In this technique, a commercially available fluorescent screen is utilized in conjunction with a video camera. This visual representation of the beam structure is digitized and enhanced through use of false color coding and displayed on a TV monitor for on-line viewing. Digitized information is stored for further off-line processing (e.g., extraction of beam profiles). An optional wire grid placed upstream of the fluor screen adds the capability of transverse emittance (or angular spread) measurement to this technique. This diagnostic allows real time observation of the beam response to parameter changes (e.g., evolution of the beam structure, shifts in the beam intensity at various spatial locations within the beam perimeter, and shifts in the beam center and position).

  10. Weight loss and lifetime medical expenditures: a case study with TRICARE prime beneficiaries.

    PubMed

    Dall, Timothy M; Zhang, Yiduo; Zhang, Shiping; Arday, David R; Sahai, Navita; Dorn, Patricia; Jain, Anjali

    2011-03-01

    TRICARE's Prime (managed care) plan spends more than $1 billion annually in medical expenditures attributed to overweight and obesity. This study estimates change in lifetime disease prevalence and medical expenditures associated with weight loss for beneficiaries in TRICARE's Prime plan. This 2010 analysis uses Markov Chain Monte Carlo simulation with demographics, biometrics, health behavior, and disease presence for 857,200 overweight and 521,800 obese beneficiaries aged 18-64 years in 2008 to model future onset of diseases linked to excess weight. Prediction equations in the simulation come from multiple sources: (1) regression analysis with longitudinal (2007-2008) TRICARE medical claims and electronic health records for 2.1 million beneficiaries; (2) regression analysis with Medical Expenditure Panel Survey (2002-2007) and National Health and Nutrition Examination Survey (1999-2008) data; (3) cancer and mortality risk from Surveillance, Epidemiology, and End Results data; and (4) published findings from clinical trials. Among overweight and obese beneficiaries, lifetime medical expenditures declined $440 (3% discount rate) for each permanent 1% reduction in body weight. This includes $590 in savings from improved health, offset by $150 in additional expenditures from prolonged life. Estimates range from $660 reduction for grossly obese adults aged <45 years to $40 gain from grossly obese adults aged 55-64 years (where expenditures from increased longevity exceed savings from improved health). If weight loss is temporary and regained after 24 months, lifetime expenditures decline by $40 per 1% reduction in body weight. Long-term benefits from weight loss are substantially greater than short-term benefits, underscoring the need for a societal perspective to combat obesity. Copyright © 2011 American Journal of Preventive Medicine. All rights reserved.

  11. The perpetual student: modeling duration of undergraduate studies based on lifetime-type educational data.

    PubMed

    Kalamatianou, Aglaia G; McClean, Sally

    2003-12-01

    It is important to educational planners to estimate the likelihood and time-scale of graduation of students enrolled on a curriculum. The particular case we are concerned with, emerges when studies are not completed in the prescribed interval of time. Under these circumstances we use a framework of survival analysis applied to lifetime-type educational data to examine the distribution of duration of undergraduate studies for 10,313 students, enrolled in a Greek university during ten consecutive academic years. Non-parametric and parametric survival models have been developed for handling this distribution as well as a modified procedure for testing goodness-of-fit of the models. Data censoring was taken into account in the statistical analysis and the problems of thresholding of graduation and of perpetual students are also addressed. We found that the proposed parametric model adequately describes the empirical distribution provided by non-parametric estimation. We also found significant difference between duration of studies of men and women students. The proposed methodology could be useful to analyse data from any other type and level of education or general lifetime data with similar characteristics.

  12. Simulations of beam-beam and beam-wire interactions in RHIC

    SciTech Connect

    Kim, Hyung J.; Sen, Tanaji; Abreu, Natalia P.; Fischer, Wolfram; /Brookhaven

    2009-02-01

    The beam-beam interaction is one of the dominant sources of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and strong localized long-range beam-beam effects are experimentally investigated in the RHIC collider. Tune shift, beam transfer function, and beam loss rate are measured in dedicated experiments. In this paper, they report on simulations to study the effect of beam-wire interactions based on diffusive apertures, beam loss rates, and beam transfer function using a parallelized weak-strong beam simulation code (BBSIMC). The simulation results are compared with measurements performed in RHIC during 2007 and 2008.

  13. Sex differences in lifetime risk and first manifestation of cardiovascular disease: prospective population based cohort study.

    PubMed

    Leening, Maarten J G; Ferket, Bart S; Steyerberg, Ewout W; Kavousi, Maryam; Deckers, Jaap W; Nieboer, Daan; Heeringa, Jan; Portegies, Marileen L P; Hofman, Albert; Ikram, M Arfan; Hunink, M G Myriam; Franco, Oscar H; Stricker, Bruno H; Witteman, Jacqueline C M; Roos-Hesselink, Jolien W

    2014-11-17

    To evaluate differences in first manifestations of cardiovascular disease between men and women in a competing risks framework. Prospective population based cohort study. People living in the community in Rotterdam, the Netherlands. 8419 participants (60.9% women) aged ≥ 55 and free from cardiovascular disease at baseline. First diagnosis of coronary heart disease (myocardial infarction, revascularisation, and coronary death), cerebrovascular disease (stroke, transient ischaemic attack, and carotid revascularisation), heart failure, or other cardiovascular death; or death from non-cardiovascular causes. Data were used to calculate lifetime risks of cardiovascular disease and its first incident manifestations adjusted for competing non-cardiovascular death. During follow-up of up to 20.1 years, 2888 participants developed cardiovascular disease (826 coronary heart disease, 1198 cerebrovascular disease, 762 heart failure, and 102 other cardiovascular death). At age 55, overall lifetime risks of cardiovascular disease were 67.1% (95% confidence interval 64.7% to 69.5%) for men and 66.4% (64.2% to 68.7%) for women. Lifetime risks of first incident manifestations of cardiovascular disease in men were 27.2% (24.1% to 30.3%) for coronary heart disease, 22.8% (20.4% to 25.1%) for cerebrovascular disease, 14.9% (13.3% to 16.6%) for heart failure, and 2.3% (1.6% to 2.9%) for other deaths from cardiovascular disease. For women the figures were 16.9% (13.5% to 20.4%), 29.8% (27.7% to 31.9%), 17.5% (15.9% to 19.2%), and 2.1% (1.6% to 2.7%), respectively. Differences in the number of events that developed over the lifespan in women compared with men (per 1000) were -7 for any cardiovascular disease, -102 for coronary heart disease, 70 for cerebrovascular disease, 26 for heart failure, and -1 for other cardiovascular death; all outcomes manifested at a higher age in women. Patterns were similar when analyses were restricted to hard atherosclerotic cardiovascular disease

  14. Baseline and lifetime alcohol consumption and risk of differentiated thyroid carcinoma in the EPIC study

    PubMed Central

    Sen, Abhijit; Tsilidis, Konstantinos K; Allen, Naomi E; Rinaldi, Sabina; Appleby, Paul N; Almquist, Martin; Schmidt, Julie A; Dahm, Christina C; Overvad, Kim; Tjønneland, Anne; Rostgaard-Hansen, Agnetha L; Clavel-Chapelon, Françoise; Baglietto, Laura; Boutron-Ruault, Marie-Christine; Kühn, Tilman; Katze, Verena A; Boeing, Heiner; Trichopoulou, Antonia; Tsironis, Christos; Lagiou, Pagona; Palli, Domenico; Pala, Valeria; Panico, Salvatore; Tumino, Rosario; Vineis, Paolo; Bueno-de-Mesquita, HB(as); Peeters, Petra H; Hjartåker, Anette; Lund, Eiliv; Weiderpass, Elisabete; Quirós, J Ramón; Agudo, Antonio; Sánchez, María- José; Arriola, Larraitz; Gavrila, Diana; Gurrea, Aurelio Barricarte; Tosovic, Ada; Hennings, Joakim; Sandström, Maria; Romieu, Isabelle; Ferrari, Pietro; Zamora-Ros, Raul; Khaw, Kay-Tee; Wareham, Nicholas J; Riboli, Elio; Gunter, Marc; Franceschi, Silvia

    2015-01-01

    Background: Results from several cohort and case–control studies suggest a protective association between current alcohol intake and risk of thyroid carcinoma, but the epidemiological evidence is not completely consistent and several questions remain unanswered. Methods: The association between alcohol consumption at recruitment and over the lifetime and risk of differentiated thyroid carcinoma was examined in the European Prospective Investigation into Cancer and Nutrition. Among 477 263 eligible participants (70% women), 556 (90% women) were diagnosed with differentiated thyroid carcinoma over a mean follow-up of 11 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using multivariable Cox proportional hazards models. Results: Compared with participants consuming 0.1–4.9 g of alcohol per day at recruitment, participants consuming 15 or more grams (approximately 1–1.5 drinks) had a 23% lower risk of differentiated thyroid carcinoma (HR=0.77; 95% CI=0.60–0.98). These findings did not differ greatly when analyses were conducted for lifetime alcohol consumption, although the risk estimates were attenuated and not statistically significant anymore. Similar results were observed by type of alcoholic beverage, by differentiated thyroid carcinoma histology or according to age, sex, smoking status, body mass index and diabetes. Conclusions: Our study provides some support to the hypothesis that moderate alcohol consumption may be associated with a lower risk of papillary and follicular thyroid carcinomas. PMID:26313664

  15. On the potential of positron lifetime spectroscopy for the study of early stages of zeolites formation from their amorphous precursors

    NASA Astrophysics Data System (ADS)

    Bosnar, S.; Kosanović, C.; Subotić, B.; Bosnar, D.; Kajcsos, Zs.; Liszkay, L.; Lohonyai, L.; Molnár, B.; Lázár, K.

    2007-02-01

    The applicability of positron lifetime (LT) spectroscopy to the study of progress of formation of Secondary Building Units (SBU) in gels yielding in FAU and LTA type zeolites was investigated. Samples were prepared from aluminosilicate gels with various degrees of local structural order. LT measurements were performed at room temperature in air and in vacuum. Coexistence of annihilation modi with long lifetime components was shown; a correlation with precursors of nucleation and type of exchanged ions was also indicated.

  16. KENO lifetimes

    SciTech Connect

    Petrie, L.; Parsons, D.K.; Spriggs, G.D.

    1997-01-30

    When performing k-eigenvalue solutions with KENO-V.a, two different prompt neutron lifetimes are estimated - a system lifetime and a neutron generation time. The meaning of these two lifetimes has been ascertained by comparing values of various neutron lifespans/lifetimes predicted by MCNP and DANTSYS based on the neutron-balance theory. The system lifetime in KENO-Va corresponds to the unweighted removal lifetime calculated by both MCNP and DANTSYS. The unweighted removal lifetime is the average time between removal events resulting from a neutron absorption or a neutron leakage. The generation time in KENO-V.a corresponds to the fission lifespan calculated by MCNP, where the fission lifespan in MCNP represents the average time for a newly born neutron to cause another fission. As such, the generation time in KENO-Va does not represent the generation time that appears in the point kinetic model. The generation time in the point kinetic model is the adjoint-weighted removal lifetime divided by k{sub eff}, which is identically equal to the adjoint-weighted neutron production rate. In small bare systems operating in the vicinity of delayed critical, the difference between the adjoint-weighted neutron generation time and the fission lifespan can be as small as a few percent. However, in reflected systems, the difference between these two quantities can be several orders of magnitude. In conclusion, the prompt neutron generation time predicted by KENO-Va corresponds to the fission lifespan of a prompt neutron in a given system. The fission lifespan is the average time from birth-to-fission and, in general, is not a good approximation for the adjoint-weighted neutron generation time that appears in the point-kinetic model.

  17. Measurements of heavy quark and lepton lifetimes

    SciTech Connect

    Jaros, J.A.

    1985-02-01

    The PEP/PETRA energy range has proved to be well-suited for the study of the lifetimes of hadrons containing the b and c quarks and the tau lepton for several reasons. First, these states comprise a large fraction of the total interaction rate in e/sup +/e/sup -/ annihilation and can be cleanly identified. Second, the storage rings have operated at high luminosity and so produced these exotic states copiously. And finally, thanks to the interplay of the Fermi coupling strength, the quark and lepton masses, and the beam energy, the expected decay lengths are in the 1/2 mm range and so are comparatively easy to measure. This pleasant coincidence of cleanly identified and abundant signal with potentially large effects has made possible the first measurements of two fundamental weak couplings, tau ..-->.. nu/sub tau/W and b ..-->.. cW. These measurements have provided a sharp test of the standard model and allowed, for the first time, the full determination of the magnitudes of the quark mixing matrix. This paper reviews the lifetime studies made at PEP during the past year. It begins with a brief review of the three detectors, DELCO, MAC and MARK II, which have reported lifetime measurements. Next it discusses two new measurements of the tau lifetime, and briefly reviews a measurement of the D/sup 0/ lifetime. Finally, it turns to measurements of the B lifetime, which are discussed in some detail. 18 references, 14 figures, 1 table.

  18. Alcohol consumption and lifetime change in cognitive ability: a gene × environment interaction study.

    PubMed

    Ritchie, Stuart J; Bates, Timothy C; Corley, Janie; McNeill, Geraldine; Davies, Gail; Liewald, David C; Starr, John M; Deary, Ian J

    2014-06-01

    Studies of the effect of alcohol consumption on cognitive ability are often confounded. One approach to avoid confounding is the Mendelian randomization design. Here, we used such a design to test the hypothesis that a genetic score for alcohol processing capacity moderates the association between alcohol consumption and lifetime change in cognitive ability. Members of the Lothian Birth Cohort 1936 completed the same test of intelligence at age 11 and 70 years. They were assessed for recent alcohol consumption in later life and genotyped for a set of four single-nucleotide polymorphisms in three alcohol dehydrogenase genes. These variants were unrelated to late-life cognition or to socioeconomic status. We found a significant gene × alcohol consumption interaction on lifetime cognitive change (p = 0.007). Individuals with higher genetic ability to process alcohol showed relative improvements in cognitive ability with more consumption, whereas those with low processing capacity showed a negative relationship between cognitive change and alcohol consumption with more consumption. The effect of alcohol consumption on cognitive change may thus depend on genetic differences in the ability to metabolize alcohol.

  19. Beam dynamics studies for the relativistic klystron two-beam accelerator experiment

    NASA Astrophysics Data System (ADS)

    Lidia, Steven M.

    2001-04-01

    Two-beam accelerators (TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band \\(~8-12 GHz\\) through Ka-band \\(~30-35 GHz\\) frequency regions. The relativistic klystron two-beam accelerator project, whose aim is to study TBAs based upon extended relativistic klystrons, is described, and a new simulation code is used to design the latter portions of the experiment. Detailed, self-consistent calculations of the beam dynamics and of the rf cavity output are presented and discussed together with a beam line design that will generate nearly 1.2 GW of power from 40 rf cavities over a 10 m distance. The simulations show that beam current losses are acceptable and that longitudinal and transverse focusing techniques are sufficiently capable of maintaining a high degree of beam quality along the entire beam line.

  20. Multi-particle weak-strong simulation of RHIC head-on beam-beam compensation.

    SciTech Connect

    Luo,Y.; Abreu, N.; Beebe-Wang, J.; FischW; Robert-Demolaize, G.

    2008-06-23

    To compensate the large tune spread generated by the beam-beam interactions in the polarized proton (pp) run in the Relativistic Heavy Ion Collider (RHIC), a low energy round Gaussian electron beam or electron lens is proposed to collide head-on with the proton beam. Using a weakstrong beam-beam interaction model, we carry out multiparticle simulations to investigate the effects of head-on beam-beam compensation on the proton beam's lifetime and emittance growth. The simplectic 6-D element-by-element tracking code SixTrack is adopted and modified for this study. The code benchmarking and preliminary simulation results are presented.

  1. Study of PRIMAVERA steel samples by positron annihilation spectroscopy technique II - Lifetime measurements

    NASA Astrophysics Data System (ADS)

    Krsjak, V.; Grafutin, V.; Ilyukhina, O.; Burcl, R.; Ballesteros, A.; Hähner, P.

    2012-02-01

    In the present article, a positron annihilation lifetime technique was used for the study of VVER-440/230 weld materials, manufactured in the frame of the international PRIMAVERA project on microstructural investigation of the irradiated WWER-440 reactor pressure vessel steel. The present results complement our previous report of positron angular correlation experiments and provide in-depth characterization of vacancy type defects behavior under irradiation and thermal treatment. The results give new insight into the previously published atom probe tomography and angular correlation of annihilation radiation studies. The measurements do not show any association of phosphorus or its segregation to the open volume defects investigated by positron annihilation spectroscopy. The embrittlement effects related to the phosphorus seem to be effectively annealed-out during 475 °C thermal treatment and the post annealing microstructure and mechanical properties of the material are consequently affected mostly by agglomerations of vacancy clusters coarsened during thermal treatment.

  2. Imputation method for lifetime exposure assessment in air pollution epidemiologic studies

    PubMed Central

    2013-01-01

    Background Environmental epidemiology, when focused on the life course of exposure to a specific pollutant, requires historical exposure estimates that are difficult to obtain for the full time period due to gaps in the historical record, especially in earlier years. We show that these gaps can be filled by applying multiple imputation methods to a formal risk equation that incorporates lifetime exposure. We also address challenges that arise, including choice of imputation method, potential bias in regression coefficients, and uncertainty in age-at-exposure sensitivities. Methods During time periods when parameters needed in the risk equation are missing for an individual, the parameters are filled by an imputation model using group level information or interpolation. A random component is added to match the variance found in the estimates for study subjects not needing imputation. The process is repeated to obtain multiple data sets, whose regressions against health data can be combined statistically to develop confidence limits using Rubin’s rules to account for the uncertainty introduced by the imputations. To test for possible recall bias between cases and controls, which can occur when historical residence location is obtained by interview, and which can lead to misclassification of imputed exposure by disease status, we introduce an “incompleteness index,” equal to the percentage of dose imputed (PDI) for a subject. “Effective doses” can be computed using different functional dependencies of relative risk on age of exposure, allowing intercomparison of different risk models. To illustrate our approach, we quantify lifetime exposure (dose) from traffic air pollution in an established case–control study on Long Island, New York, where considerable in-migration occurred over a period of many decades. Results The major result is the described approach to imputation. The illustrative example revealed potential recall bias, suggesting that regressions

  3. Interactions between natural organic ligands and trace metals studied by fluorescence lifetime and fluorescence quenching

    NASA Astrophysics Data System (ADS)

    Nouhi, Ayoub; Hajjoul, Houssam; Redon, Roland; Gagné, Jean-Pierre; Mounier, Stéphane

    2017-04-01

    Improved insight on the interactions between natural organic ligands and trace metals is of paramount importance for better understanding transport and toxicity pathways of metal ions in the environment. Fluorescence spectroscopy allows introspecting ligands-metals interactions. Time-resolved laser fluorescence spectroscopy (TRLFS) measures fluorophore lifetime probing the local molecular environment. Excitation Emission Fluorescence Matrices (EEFMs) and their statistical treatment : parallel factor analysis (PARAFAC) using PROGMEEF Matlab homemade program, can give insight on the number or nature of organic fluorophores involved in the interactions. Quenching of fluorescence by metals can occur following two processes: dynamic and static quenching (Lakowicz, 2013). In the first case, quenching is caused by physical collisions among molecules and in the second case fluorophores can form nonfluorescent complexes with quenchers. It is possible to identify the different mechanisms because each type of quenching corresponds to a different mathematical model (Lakowicz, 2013; Valeur and Berberan-Santos, 2012). In TRLFS, the study of fluorescence decay's laws induced by nanosecond pulsed laser will allow to exactly qualify the type of interaction. The crucial point of the temporal deconvolution will be the evaluation of the best fitting between the different physical models and the decays measured. From the most suitable time decay model, it will be possible to deduce the quenching which modifies the fluorescence. The aim of this study was to characterize interactions between natural organic ligands and trace metals using fluorescence tools to evaluate the fluorescence lifetime of the fluorophore, the occurrence of quenching in presence of metal, discuss its mechanism and estimate conditional stability constants if a complex organic ligand-metal is formed. This study has been done in two steps. First, we have examined the interactions between salicylic acid and copper in

  4. Study on shear behavior of FRP strengthened concrete beams

    NASA Astrophysics Data System (ADS)

    Zhao, J. K.; Xu, X. S.

    2017-04-01

    There are many researches on concrete bending beams reinforced with FRP, and the beam section of the bending strength is enhanced, it is necessary to carry out an oblique section bearing capacity review, if the bearing capacity is insufficient, it is also necessary to strengthen, so as to ensure the ductility of the beam and meet the needs of Engineering safety. In this paper, four concrete beams strengthened with different fibers (CFRP, HFRP and GFRP) were used to study the stress characteristics, failure forms, reasonable reinforcement methods, beam strain conditions, bearing capacity, stiffness and deformation capacity of shear behavior of concrete beams strengthened with different fibers and different forms of reinforcement. The experimental results showed that the FRP reinforcement can not only improve the shear bearing capacity and ultimate deformation of beam, but also increase the stiffness of the beam, reduce the bending deformation under the same load beam, and delay the extension of diagonal cracks.

  5. Study of UV Cu + Ne – CuBr laser lifetime by statistical methods

    SciTech Connect

    Iliev, I P; Gocheva-Ilieva, S G

    2013-11-30

    On the basis of a large amount of experimental data, statistical investigation of the average lifetime of a UV Cu + Ne – CuBr laser depending on ten input physical laser parameters is carried out. It is found that only three of the parameters have a substantial influence on the laser lifetime. Physical analysis and interpretation of the results are provided. (lasers)

  6. Rebuilding the Brookhaven high flux beam reactor: A feasibility study

    SciTech Connect

    Brynda, W.J.; Passell, L.; Rorer, D.C.

    1995-01-01

    After nearly thirty years of operation, Brookhaven`s High Flux Beam Reactor (HFBR) is still one of the world`s premier steady-state neutron sources. A major center for condensed matter studies, it currently supports fifteen separate beamlines conducting research in fields as diverse as crystallography, solid-state, nuclear and surface physics, polymer physics and structural biology and will very likely be able to do so for perhaps another decade. But beyond that point the HFBR will be running on borrowed time. Unless appropriate remedial action is taken, progressive radiation-induced embrittlement problems will eventually shut it down. Recognizing the HFBR`s value as a national scientific resource, members of the Laboratory`s scientific and reactor operations staffs began earlier this year to consider what could be done both to extend its useful life and to assure that it continues to provide state-of-the-art research facilities for the scientific community. This report summarizes the findings of that study. It addresses two basic issues: (i) identification and replacement of lifetime-limiting components and (ii) modifications and additions that could expand and enhance the reactor`s research capabilities.

  7. Lung cancer in lifetime nonsmoking men – results of a case-control study in Germany

    PubMed Central

    Kreuzer, M; Gerken, M; Kreienbrock, L; Wellmann, J; Wichmann, H E

    2001-01-01

    Epidemiological studies of lung cancer among nonsmoking men are few. This case–control study was conducted among lifetime nonsmoking men between 1990 and 1996 in Germany to examine lung cancer risk in relation to occupation, environmental tobacco smoke, residential radon, family history of cancer and previous lung disease. A total of 58 male cases with confirmed primary lung cancer and 803 male population controls who had never smoked more than 400 cigarettes in their lifetime were personally interviewed by a standardized questionnaire. In addition, 1-year radon measurements in the living and bedroom of the subjects' last dwelling were carried out. Unconditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI). Having ever worked in a job with known lung carcinogens was associated with a two-fold significantly increased lung cancer risk (OR = 2.2; Cl = 1.0–5.0), adjusted for age and region. The linear trend test for lung-cancer risk associated with radon exposure was close to statistical significance, demonstrating an excess relative risk for an increase in exposure of 100 Bq m−3 of 0.43 (P = 0.052). Nonsignificantly elevated effects of exposure to environmental tobacco smoke in public transportation and in social settings were observed. No associations with a family history of cancer or previous lung diseases were found. Our results indicate that occupational carcinogens and indoor radon may play a role in some lung cancers in nonsmoking men. © 2001 Cancer Research Campaign http://www.bjcancer.com PMID:11139328

  8. Emittance compensation studies of photoinjector beams with angular momentum

    SciTech Connect

    Lidia, Steven

    2003-05-19

    Beam dynamics studies on the FNPL photo injector that seek to optimize the transport of intense electron beams with large values of canonical angular momentum have been performed. These studies investigate the effect of solenoid emittance compensation on beams that evolve under the combined influence of intense space charge forces and large angular momentum. We present details of experimental measurements and supporting simulations of beam envelope evolution.

  9. MR LLRF VXI upgrade beam study period

    SciTech Connect

    Mesiner, K.; /Fermilab

    1995-01-01

    AD/RFI/LLRF group personnel performed several studies with the MR LLRF VXI upgrade system during the evening of 7/29/95. The study period lasted about 4 hours. The MR operating conditions were a mixture of $29 and $2B cycles, with beam injected only on the $29. The author believes the $2B cycles were present for reasons unrelated to the study. The basic study period goal was to test the initial VXI version of MR LLRF finite state machine (FSM) execution. This goal represents what has been called MR LLRF VXI Upgrade Implementation Stage No.2 throughout presentations and documentation on the upgrade project. The test includes control of MR LLRF NIM hardware, the MR RF cavities, and beam via XVI TTL FSM outputs. Numerous MR LLRF VXI system objects, or components, must work together correctly for a successful test. Very briefly, the required objects include VXI Front End hardware, the ACNET/Front End interface code, and the VXI/NIM Interface chassis (the chassis solves VXI-CAMAC-NIM RF and FSM output connectivity and development problems). Though this initial FSM does not yet fully support Upgrade Implementation Stage 2 functionality, all code and hardware for the following basic functionality is tested.

  10. Lifetimes and electromagnetic transition strength in 157Dy

    NASA Astrophysics Data System (ADS)

    Gladnishki, K. A.; Petkov, P.; Dewald, A.; Jolie, J.; Möller, O.; Saha, B.; Fitzler, A.; Jessen, K.; Tonev, D.; Klug, T.; Heinze, S.; von Brentano, P.; Rainovski, G.; Trichkova, M.; Bazzacco, D.; Ur, C. A.; Farnea, E.; Axiotis, M.; Lunardi, S.; de Angelis, G.; Napoli, D. R.; Marginean, N.; Martinez, T.; Caprio, M. A.

    2016-06-01

    Excited states in 157Dy have been studied by γ-γ coincidence measurements via the reaction 124Sn(36S,3n) at a beam energy of 155MeV. Lifetimes of the relatively lower-spin states in 157Dy were measured by means of the Recoil Distance Dopplershift technique in the coincidence mode. The experiment was performed at the Laboratori Nazionali di Legnaro with the GASP array and the Cologne plunger device. With the same setup a Doppler- shift attenuation (DSA) lifetime measurement was performed for the higher spin states. The Differential decay-curve method was applied for the lifetime determination.

  11. Fluorescence lifetime and acrylamide quenching studies of the interactions between troponin subunits.

    PubMed

    Leavis, P C; Gowell, E; Tao, T

    1984-08-28

    Fluorescence lifetime and acrylamide quenching studies were carried out to characterize the interactions between the subunits of troponin under various conditions of metal ion binding. Troponin C was labeled at Cys-98 with N-(iodoacetyl)-N'-(5-sulfo-1-naphthyl)ethylenediamine. In the presence of Ca2+, the fluorescence decay of labeled troponin C (TnC*) was monoexponential, lifetime tau = 15.5 ns and quenching rate constant kq = 2.97 X 10(8) M-1 s-1. In the absence of Ca2+, the decay was resolvable into a major component with tau = 11.9 ns and a minor component with tau = 20.5 ns, with corresponding values of kq = 4.80 X 10(8) and 0.66 X 10(8) M-1 s-1, respectively. Upon the binding of either troponin I (TnI) or troponin T (TnT) in the presence of Ca2+, tau increased to approximately 18 ns, and kq decreased to approximately 0.8 X 10(8) M-1 s-1. For the Ca2+ form of the TnC*-TnI-TnT ternary complex, values of tau = 17.6 ns and kq = 1.73 X 10(8) M-1 s-1 were obtained. These values did not vary significantly when Ca2+ was removed, or when Mg2+ replaced Ca2+. These findings were interpreted as follows: the region around Cys-98 of TnC* adopts a looser conformation upon the removal of Ca2+ from the high-affinity sites. Both TnI and TnT bind to TnC* in the region containing Cys-98. The probe is shielded from the solvent to a greater extent in the binary complexes than in the ternary complex.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Generation of high-power single-frequency 397.5 nm laser with long lifetime and perfect beam quality in an external enhancement-cavity with MgO-doped PPSLT.

    PubMed

    Lu, Huadong; Wei, Jiao; Wei, Yixiao; Su, Jing; Peng, Kunchi

    2016-10-17

    Continuous-wave single-frequency high power 397.5 nm laser with long lifetime and perfect beam quality is one of the essential resource to generate the squeezed and entanglement states of optical beams resonant with D1 line of Rubidium atoms at 795 nm. In this paper, We present the experimental generation of single-frequency high power 397.5 nm ultra-violet (UV) laser with long lifetime and perfect beam quality by using periodically poled MgO-doped stoichiometric lithium tantalate (MgO:PPSLT) crystal as the frequency doubler in an external enhancement ring cavity. When the transmission of the input coupler is 5.5%, the maximal output power of single-frequency 397.5 nm UV laser of 407 mW is obtained under the incident pump power of 1.9 W with the corresponding conversion efficiency of 22.8%. When the output power is 290 mW, the measured power stability and the beam quality are lower than 0.28% and 1.02, respectively. Moreover, any damage is not observed in our experiment which lasts about 1 year.

  13. Beam-beam studies for the proposed SLAC/LBL/LLNL B Factory

    SciTech Connect

    Furman, M.A.

    1991-05-01

    We present a summary of beam-beam dynamics studies that have been carried out to date for the proposed SLAC/LBL/LLNL B Factory. Most of the material presented here is contained in the proposal's Conceptual Design Report, although post-CDR studies are also presented. 15 refs., 6 figs., 2 tabs.

  14. Studies of Ion Beam Charge Neutralization by Ferroelectric Plasma Sources

    NASA Astrophysics Data System (ADS)

    Stepanov, A.; Gilson, E. P.; Grisham, L.; Davidson, R. C.

    2013-10-01

    Space-charge forces limit the possible transverse compression of high perveance ion beams that are used in ion-beam-driven high energy density physics applications; the minimum radius to which a beam can be focused is an increasing function of perveance. The limit can be overcome if a plasma is introduced in the beam path between the focusing element and the target in order to neutralize the space charge of the beam. This concept has been implemented on the Neutralized Drift Compression eXperiment (NDCX) at LBNL using Ferroelectric Plasma Sources (FEPS). In our experiment at PPPL, we propagate a perveance-dominated ion beam through a FEPS to study the effect of the neutralizing plasma on the beam envelope and its evolution in time. A 30-60 keV space-charge-dominated Argon beam is focused with an Einzel lens into a FEPS located at the beam waist. The beam is intercepted downstream from the FEPS by a movable Faraday cup that provides time-resolved 2D current density profiles of the beam spot on target. We report results on: (a) dependence of charge neutralization on FEPS plasma density; (b) effects on beam emittance, and (c) time evolution of the beam envelope after the FEPS pulse. Research supported by the U.S. Department of Energy.

  15. Actin cytoskeleton-dependent Rab GTPase-regulated angiotensin type I receptor lysosomal degradation studied by fluorescence lifetime imaging microscopy

    NASA Astrophysics Data System (ADS)

    Li, Hewang; Yu, Peiying; Sun, Yuansheng; Felder, Robin A.; Periasamy, Ammasi; Jose, Pedro A.

    2010-09-01

    The dynamic regulation of the cellular trafficking of human angiotensin (Ang) type 1 receptor (AT1R) is not well understood. Therefore, we investigated the cellular trafficking of AT1R-enhanced green fluorescent protein (EGFP) (AT1R-EGFP) heterologously expressed in HEK293 cells by determining the change in donor lifetime (AT1R-EGFP) in the presence or absence of acceptor(s) using fluorescence lifetime imaging-fluorescence resonance energy transfer (FRET) microscopy. The average lifetime of AT1R-EGFP in our donor-alone samples was ~2.33 ns. The basal state lifetime was shortened slightly in the presence of Rab5 (2.01+/-0.10 ns) or Rab7 (2.11+/-0.11 ns) labeled with Alexa 555, as the acceptor fluorophore. A 5-min Ang II treatment markedly shortened the lifetime of AT1R-EGFP in the presence of Rab5-Alexa 555 (1.78+/-0.31 ns) but was affected minimally in the presence of Rab7-Alexa 555 (2.09+/-0.37 ns). A 30-min Ang II treatment further decreased the AT1R-EGFP lifetime in the presence of both Rab5- and Rab7-Alexa 555. Latrunculin A but not nocodazole pretreatment blocked the ability of Ang II to shorten the AT1R-EGFP lifetime. The occurrence of FRET between AT1R-EGFP (donor) and LAMP1-Alexa 555 (acceptor) with Ang II stimulation was impaired by photobleaching the acceptor. These studies demonstrate that Ang II-induced AT1R lysosomal degradation through its association with LAMP1 is regulated by Rab5/7 via mechanisms that are dependent on intact actin cytoskeletons.

  16. Hyperspectral fluorescence lifetime fibre probe spectroscopy for use in the study and diagnosis of osteoarthritis and skin cancer

    NASA Astrophysics Data System (ADS)

    Thompson, Alex; Manning, Hugh; Brydegaard, Mikkel; Coda, Sergio; Kennedy, Gordon; Patalay, Rakesh; Waitong-Braemming, Ulrika; De Beule, Pieter; Neil, Mark; Andersson-Engels, Stefan; Itoh, Yoshifumi; Bendsøe, Niels; Dunsby, Christopher; Svanberg, Katarina; French, Paul M.

    2011-03-01

    We present the application of two fibre-optic-coupled time-resolved spectrofluorometers and a compact steady-state diffuse reflected light/fluorescence spectrometer to in vivo and ex vivo studies of skin cancer and osteoarthritis. In a clinical study of skin cancer, 27 lesions on 25 patients were investigated in vivo before surgical excision of the region measured. Preliminary analysis reveals a statistically significant decrease in the autofluorescence lifetime of basal cell carcinomas compared to neighbouring healthy tissue. A study of autofluorescence signals associated with the onset of osteoarthritis indicates autofluorescence lifetime changes associated with collagen degradation.

  17. Beam-Beam Simulation Studies for PEP-II and KEKB

    SciTech Connect

    Tawada, M.

    2004-01-09

    The study issues for this project are: (1) Comparison of 3D PIC beam-beam simulation code; (2) Comparison of 2D PIC beam-beam simulation code; (3) Comparison between 2D PIC solver and exact Gauss solution in Weak-Strong simulation; (4) Comparison between head-on collision and xangle+crab cavity by KEK code; (5) Crossing angle dependence of luminosity for PEP-II and KEKB parameter; and (6) Tune scan for PEP-II by using weak-strong code at the crossing angle of 0, 3, 5 mrad.

  18. Feasibility study for mega-electron-volt electron beam tomography

    SciTech Connect

    Hampel, U.; Baertling, Y.; Hoppe, D.; Kuksanov, N.; Fadeev, S.; Salimov, R.

    2012-09-15

    Electron beam tomography is a promising imaging modality for the study of fast technical processes. But for many technical objects of interest x rays of several hundreds of keV energy are required to achieve sufficient material penetration. In this article we report on a feasibility study for fast electron beam computed tomography with a 1 MeV electron beam. The experimental setup comprises an electrostatic accelerator with beam optics, transmission target, and a single x-ray detector. We employed an inverse fan-beam tomography approach with radiographic projections being generated from the linearly moving x-ray source. Angular projections were obtained by rotating the object.

  19. TEBPP: Theoretical and Experimental study of Beam-Plasma-Physics

    NASA Technical Reports Server (NTRS)

    Anderson, H. R.; Bernstein, W.; Linson, L. M.; Papadopoulos, K.; Kellogg, P. J.; Szuszczewicz, E. P.; Hallinan, T. J.; Leinbach, H.

    1980-01-01

    The interaction of an electron beam (0 to 10 keV, 0 to 1.5 Amp) with the plasma and neutral atmospheres at 200 to 400 km altitude is studied with emphasis on applications to near Earth and cosmical plasmas. The interaction occurs in four space time regions: (1) near electron gun, beam coming into equilibrium with medium; (2) equilibrium propagation in ionosphere; (3) ahead of beam pulse, temporal and spatial precursors; (4) behind a beam pulse. While region 2 is of the greatest interest, it is essential to study Region 1 because it determines the characteristics of the beam as it enters 2 through 4.

  20. Feasibility study for mega-electron-volt electron beam tomography.

    PubMed

    Hampel, U; Bärtling, Y; Hoppe, D; Kuksanov, N; Fadeev, S; Salimov, R

    2012-09-01

    Electron beam tomography is a promising imaging modality for the study of fast technical processes. But for many technical objects of interest x rays of several hundreds of keV energy are required to achieve sufficient material penetration. In this article we report on a feasibility study for fast electron beam computed tomography with a 1 MeV electron beam. The experimental setup comprises an electrostatic accelerator with beam optics, transmission target, and a single x-ray detector. We employed an inverse fan-beam tomography approach with radiographic projections being generated from the linearly moving x-ray source. Angular projections were obtained by rotating the object.

  1. Annular Laser Beam Cladding Process Feasibility Study

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Alexander; Jeromen, Andrej; Levy, Gideon; Fujishima, Makoto; Govekar, Edvard

    In the paper a novel annular - ring shaped - laser beam cladding head and related cladding process are presented. In the cladding head a laser beam is shaped into an annular ring and guided coaxially with the powder tube disposing the powder jet in the centre of the focused annular laser beam ring. An experimental process feasibility analysis was performed using a Nd:YAG pulsed laser system with a maximal average power 250 W. Beside the known influencing parameters of laser cladding process including the powder mass flow, workpiece feeding velocity, and laser beam intensity, the important parameters related to the annular laser beam caustics were defined. The process feasibility and influence of the process parameters on powder catchment efficiency was analysed based on the cladding experiments of SS 316L powder on SS 304 workpiece material. The potential benefits related to the annular laser beam melt pool geometry and related powder catchment efficiency are discussed.

  2. Positron annihilation lifetime study of polyvinylpyrrolidone for nanoparticle-stabilizing pharmaceuticals.

    PubMed

    Shpotyuk, O; Bujňáková, Z; Baláž, P; Ingram, A; Shpotyuk, Y

    2016-01-05

    Positron annihilation lifetime spectroscopy was applied to characterize free-volume structure of polyvinylpyrrolidone used as nonionic stabilizer in the production of many nanocomposite pharmaceuticals. The polymer samples with an average molecular weight of 40,000 g mol(-1) were pelletized in a single-punch tableting machine under an applied pressure of 0.7 GPa. Strong mixing in channels of positron and positronium trapping were revealed in the polyvinylpyrrolidone pellets. The positron lifetime spectra accumulated under normal measuring statistics were analysed in terms of unconstrained three- and four-term decomposition, the latter being also realized under fixed 0.125 ns lifetime proper to para-positronium self-annihilation in a vacuum. It was shown that average positron lifetime extracted from each decomposition was primary defined by long-lived ortho-positronium component. The positron lifetime spectra treated within unconstrained three-term fitting were in obvious preference, giving third positron lifetime dominated by ortho-positronium pick-off annihilation in a polymer matrix. This fitting procedure was most meaningful, when analysing expected positron trapping sites in polyvinylpyrrolidone-stabilized nanocomposite pharmaceuticals.

  3. Technology integration box beam failure study

    NASA Technical Reports Server (NTRS)

    Shuart, Mark J.; Ambur, D. R.; Davis, D. D., Jr.; Davis, Randall C.; Farley, G. L.; Lotts, C. G.; Wang, J. T.

    1992-01-01

    Composite structures have the potential to be cost effective, structurally efficient primary aircraft structures. As part of the Advanced Composite Technology (ACT) program to exploit this potential for heavily loaded aircraft structures, the design and fabrication of the technology integration box beam (TIBB) was completed. The TIBB is an advanced composite prototype structure for the center wing section of the Lockheed C-130 aircraft. The TIBB was tested for downbending, upbending, torsion, and combined upbending and torsion load conditions to verify the design. The TIBB failed at 83 percent of design ultimate load for the combined upbending and torsion load condition. Current analytical and experimental results are described for a study of the mechanisms that led to the failure of the TIBB. Experimental results include load, strain, and deflection data. An analytical study was conducted of the TIBB structural response. Analytical results include strain and deflection results from a global analysis of the TIBB.

  4. Measurements of photocathode operational lifetime at beam currents up to 10-mA using an improved DC high voltage GaAs photogun

    SciTech Connect

    J. Grames; M. Poelker; P. Adderley; J. Brittian; J. Clark; J. Hansknecht; D. Machie; M.L. Stutzman; K. Surles-Law

    2007-06-01

    This work extends past research at Jefferson Lab aimed at better appreciating the mechanisms that limit photocathode operational lifetime at high current (> 1 mA). Specifically, the performance of an improved 100 kV DC high voltage load locked photogun will be described. Although difficult to measure directly, we believe the new gun has better vacuum conditions compared to the original gun, as indicated by enhanced photocathode lifetimes exceeding 2000 C using a 1.55 mm diameter drive laser spot at the photocathode. In addition, the dependence of the lifetime on the laser spot size at the photocathode was measured and a charge density lifetime exceeding 10^6 C/cm^2 was measured with a 0.32 mm laser spot diameter.

  5. The lifetime of CFC substitutes studied by a network trained with chaotic mapping modified genetic algorithm and DFT calculations.

    PubMed

    Lü, Q; Wu, H; Yu, R; Shen, G

    2004-08-01

    The hydrohaloalkanes have attracted much attention as potential substitutes of chlorofluorocarbons (CFCs) that deplete the ozone layer and lead to great high global warming. Having a short atmospheric lifetime is very important for the potential substitutes that may also induce ozone depletion and yield high global warming gases to be put in use. Quantitative structure-activity relationship (QSAR) studies were presented for their lifetimes aided by the quantum chemistry parameters including net charges, Mulliken overlaps, E(HOMO) and E(LUMO) based on the density functional theory (DFT) at B3PW91 level, and the C-H bond dissociation energy based on AM1 calculations. Outstanding features of the logistic mapping, a simple chaotic system, especially the inherent ability to search the space of interest exhaustively have been utilized. The chaotic mapping aided genetic algorithm artificial neural network training scheme (CGANN) showed better performance than the conventional genetic algorithm ANN training when the structure of the data set was not favorable. The lifetimes of HFCs and HCs appeared to be greatly dependent on their energies of the highest occupied molecular orbitals. The perference of the RMSRE comparing to RMSE as objective function of ANN training was better for the samples of interest with relatively short lifetimes. C(2)H(6) and C(3)H(8) as potential green substitutes of CFCs present relatively short lifetimes.

  6. Lifetime sexual violence and childbirth expectations - A Norwegian population based cohort study.

    PubMed

    Henriksen, Lena; Schei, Berit; Lukasse, Mirjam

    2016-05-01

    this study aimed to explore the association between lifetime sexual violence and expectations about childbirth. Norwegian population-based cohort study. women presenting for routine ultrasound examinations were recruited to the Norwegian Mother and Child Cohort Study between 1999 and 2008. 78,660 pregnant women. sexual violence and expectations about childbirth were self-reported during pregnancy using postal questionnaires. Risk estimations were performed using multivariable logistic regression analysis and stratified by parity. fear of childbirth, the thoughts about pain relief, worries about the infant's health and looking forward to the arrival of the infant. of 78,660 women, 18.4% reported a history of sexual violence and 0.9% were exposed to sexual violence within the last 12 months, including during the current pregnancy. We found that nulliparous women who reported previous or recent sexual violence had a decrease in the odds of looking forward to the arrival of the infant with an AOR of 0.8 (95% CI 0.7-0.9) and 0.4 (95% CI 0.3-0.6), respectively, compared to non-abused women. The same pattern was observed among multiparous women and they were more likely to report worries about the infant's health. Severe sexual violence (rape) was associated with concerns about childbirth, especially for nulliparous women that were more likely to express fear of birth, a hope for a pain-free birth, a desire for caesarean section and worries about the infant's health than non-exposed women. women with a lifetime exposure to sexual violence, both past experiences and within the last 12 months, were less likely to look forward to the arrival of the infant than non-exposed women, and they were more likely to worry about the infant's health. Women with experiences of severe sexual violence (rape) had more concerns about childbirth than women without this experience. This finding shows that exploring women's attitudes toward childbirth may work as an approach when examining

  7. Beam Dynamics Simulation Platform and Studies of Beam Breakup in Dielectric Wakefield Structures

    SciTech Connect

    Schoessow, P.; Kanareykin, A.; Jing, C.; Kustov, A.; Altmark, A.; Gai, W.

    2010-11-04

    A particle-Green's function beam dynamics code (BBU-3000) to study beam breakup effects is incorporated into a parallel computing framework based on the Boinc software environment, and supports both task farming on a heterogeneous cluster and local grid computing. User access to the platform is through a web browser.

  8. Beam Dynamics Simulation Platform and Studies of Beam Breakup in Dielectric Wakefield Structures

    NASA Astrophysics Data System (ADS)

    Schoessow, P.; Kanareykin, A.; Jing, C.; Kustov, A.; Altmark, A.; Gai, W.

    2010-11-01

    A particle-Green's function beam dynamics code (BBU-3000) to study beam breakup effects is incorporated into a parallel computing framework based on the Boinc software environment, and supports both task farming on a heterogeneous cluster and local grid computing. User access to the platform is through a web browser.

  9. A Study on Wireless Charging for Prolonging the Lifetime of Wireless Sensor Networks

    PubMed Central

    Tu, Weijian; Xu, Xianghua; Ye, Tingcong; Cheng, Zongmao

    2017-01-01

    Wireless charging is an important issue in wireless sensor networks, since it can provide an emerging and effective solution in the absence of other power supplies. The state-of-the-art methods employ a mobile car and a predefined moving path to charge the sensor nodes in the network. Previous studies only consider a factor of the network (i.e., residual energy of sensor node) as a constraint to design the wireless charging strategy. However, other factors, such as the travelled distance of the mobile car, can also affect the effectiveness of wireless charging strategy. In this work, we study wireless charging strategy based on the analysis of a combination of two factors, including the residual energy of sensor nodes and the travelled distance of the charging car. Firstly, we theoretically analyze the limited size of the sensor network to match the capability of a charging car. Then, the networked factors are selected as the weights of traveling salesman problem (TSP) to design the moving path of the charging car. Thirdly, the charging time of each sensor node is computed based on the linear programming problem for the charging car. Finally, a charging period for the network is studied. The experimental results show that the proposed approach can significantly maximize the lifetime of the wireless sensor network. PMID:28677639

  10. A Study on Wireless Charging for Prolonging the Lifetime of Wireless Sensor Networks.

    PubMed

    Tu, Weijian; Xu, Xianghua; Ye, Tingcong; Cheng, Zongmao

    2017-07-04

    Wireless charging is an important issue in wireless sensor networks, since it can provide an emerging and effective solution in the absence of other power supplies. The state-of-the-art methods employ a mobile car and a predefined moving path to charge the sensor nodes in the network. Previous studies only consider a factor of the network (i.e., residual energy of sensor node) as a constraint to design the wireless charging strategy. However, other factors, such as the travelled distance of the mobile car, can also affect the effectiveness of wireless charging strategy. In this work, we study wireless charging strategy based on the analysis of a combination of two factors, including the residual energy of sensor nodes and the travelled distance of the charging car. Firstly, we theoretically analyze the limited size of the sensor network to match the capability of a charging car. Then, the networked factors are selected as the weights of traveling salesman problem (TSP) to design the moving path of the charging car. Thirdly, the charging time of each sensor node is computed based on the linear programming problem for the charging car. Finally, a charging period for the network is studied. The experimental results show that the proposed approach can significantly maximize the lifetime of the wireless sensor network.

  11. Study on space charge compensation in negative hydrogen ion beam.

    PubMed

    Zhang, A L; Peng, S X; Ren, H T; Zhang, T; Zhang, J F; Xu, Y; Guo, Z Y; Chen, J E

    2016-02-01

    Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H(+) beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H(-) beam from a 2.45 GHz microwave driven H(-) ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results.

  12. Study on space charge compensation in negative hydrogen ion beam

    SciTech Connect

    Zhang, A. L.; Chen, J. E.; Peng, S. X. Ren, H. T.; Zhang, T.; Zhang, J. F.; Xu, Y.; Guo, Z. Y.

    2016-02-15

    Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H{sup +} beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H{sup −} beam from a 2.45 GHz microwave driven H{sup −} ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results.

  13. Lifetime Measurements in ^124Xe.

    NASA Astrophysics Data System (ADS)

    Govil, I. M.; Patnaik, D.; Kumar, A.; Garg, U.; Ghugre, S. S.; Johnson, T.; Kharraja, B.; Naguleswaran, S.; Walpe, J. C.; Kaczarowski, R.

    1996-10-01

    Lifetimes of lower excited states in ^124Xe have been measured using the Recoil-Distance Doppler-shift technique. The nucleus ^124Xe was produced by the ^18O + ^110Pd reaction at a beam energy of 66 MeV. The Recoil-Distance measurements were performed using the Notre Dame plunger. The lifetimes of the 2^+, 4^+, 6^+ and 8^+ states of the ground-state band were extracted, using the computer code "LIFETIME"^a, including the corrections due to the side-feeding and the nuclear deorientation effects. The lifetime of the 2^+1 state agrees well with the Coloumb-excitation data ^b. The measured B(E2) values are compared with the existing Algebraic and Multishell models. ^a Computer code LIFETIME, J.C. Wells, ORNL, Oak-Ridge, TN. ^b D.M Gordon et al, PRC 12, 628 (1975).

  14. Fast beam studies of free radical photodissociation

    SciTech Connect

    Neumark, D.M.

    1993-12-01

    The authors have developed a novel technique for studying the photodissociation spectroscopy and dynamics of free radicals. In these experiments, radicals are generated by laser photodetachment of a fast (6-8 keV) mass-selected negative ion beam. The resulting radicals are photodissociated with a second laser, and the photofragments are collected and detected with high efficiency using a microchannel plate detector. The overall process is: ABC{sup -} {yields} ABC + e{sup -} {yields} A + BC, AB + C. Two types of fragment detection schemes are used. To map out the photodissociation cross-section of the radical, the photodissociation laser is scanned and the total photofragment yield is measured as a function of wavelength. In other experiments, the photodissociation frequency is fixed and the photofragment masses, kinetic energy release, and scattering angle is determined for each photodissociation event.

  15. Multiple beam antenna/switch system study

    NASA Technical Reports Server (NTRS)

    1989-01-01

    In the study of the Multiple Beam Antenna/Switch for the space to ground link (SGL) uplink and downlink services, several issues related to system engineering, antenna, transmit/receive, and switch systems were addressed and the results are provided. Bandwidth allocation at Ku band is inadequate to serve the data rate requirements for the forward and return services. Rain and depolarization effects at EHF, especially at Ka band, pose a significant threat to the link availabilities at heavy rain areas. Hardware induced effects such as the nonlinear characteristics of the power amplifier may necessitate the use of linearizers and limiters. It is also important to identify the components that are susceptible to the space radiation effects and shield or redesign them with rad-hard technologies for meeting the requirements of the space environment.

  16. Lifetime Organophosphorous Insecticide Use among Private Pesticide Applicators in the Agricultural Health Study

    PubMed Central

    Hoppin, Jane A.; Long, Stuart; Umbach, David M.; Lubin, Jay H.; Starks, Sarah; Gerr, Fred; Thomas, Kent; Hines, Cynthia J; Weichenthal, Scott; Kamel, Freya; Koutros, Stella; Alavanja, Michael; Beane Freeman, Laura E.; Sandler, Dale P.

    2012-01-01

    Organophosphorous insecticides (OPs) are the most commonly used insecticides in US agriculture, but little information is available regarding specific OP use by individual farmers. We describe OP use for licensed private pesticide applicators from Iowa and North Carolina in the Agricultural Health Study (AHS) using lifetime pesticide use data from 701 randomly selected male participants collected at three time periods. Of 27 OPs studied, 20 were used by >1%. Overall, 95% had ever applied at least one OP. The median number of different OPs used was 4 (maximum=13). Malathion was the most commonly used OP (74%) followed by chlorpyrifos (54%). OP use declined over time. At the first interview (1993–1997), 68% of participants had applied OPs in the past year; by the last interview (2005–2007), only 42% had. Similarly, median annual application days of OPs declined from 13.5 to 6 days. While OP use was common, the specific OPs used varied by state, time period, and individual. Much of the variability in OP use was associated with the choice of OP, rather than the frequency or duration of application. Information on farmers’ OP use enhances our ability to characterize and understand the potential health effects of multiple OP exposures. PMID:22854518

  17. Personalized prediction of lifetime benefits with statin therapy for asymptomatic individuals: a modeling study.

    PubMed

    Ferket, Bart S; van Kempen, Bob J H; Heeringa, Jan; Spronk, Sandra; Fleischmann, Kirsten E; Nijhuis, Rogier L G; Hofman, Albert; Steyerberg, Ewout W; Hunink, M G Myriam

    2012-01-01

    Physicians need to inform asymptomatic individuals about personalized outcomes of statin therapy for primary prevention of cardiovascular disease (CVD). However, current prediction models focus on short-term outcomes and ignore the competing risk of death due to other causes. We aimed to predict the potential lifetime benefits with statin therapy, taking into account competing risks. A microsimulation model based on 5-y follow-up data from the Rotterdam Study, a population-based cohort of individuals aged 55 y and older living in the Ommoord district of Rotterdam, the Netherlands, was used to estimate lifetime outcomes with and without statin therapy. The model was validated in-sample using 10-y follow-up data. We used baseline variables and model output to construct (1) a web-based calculator for gains in total and CVD-free life expectancy and (2) color charts for comparing these gains to the Systematic Coronary Risk Evaluation (SCORE) charts. In 2,428 participants (mean age 67.7 y, 35.5% men), statin therapy increased total life expectancy by 0.3 y (SD 0.2) and CVD-free life expectancy by 0.7 y (SD 0.4). Age, sex, smoking, blood pressure, hypertension, lipids, diabetes, glucose, body mass index, waist-to-hip ratio, and creatinine were included in the calculator. Gains in total and CVD-free life expectancy increased with blood pressure, unfavorable lipid levels, and body mass index after multivariable adjustment. Gains decreased considerably with advancing age, while SCORE 10-y CVD mortality risk increased with age. Twenty-five percent of participants with a low SCORE risk achieved equal or larger gains in CVD-free life expectancy than the median gain in participants with a high SCORE risk. We developed tools to predict personalized increases in total and CVD-free life expectancy with statin therapy. The predicted gains we found are small. If the underlying model is validated in an independent cohort, the tools may be useful in discussing with patients their

  18. Personalized Prediction of Lifetime Benefits with Statin Therapy for Asymptomatic Individuals: A Modeling Study

    PubMed Central

    Ferket, Bart S.; van Kempen, Bob J. H.; Heeringa, Jan; Spronk, Sandra; Fleischmann, Kirsten E.; Nijhuis, Rogier L. G.; Hofman, Albert; Steyerberg, Ewout W.; Hunink, M. G. Myriam

    2012-01-01

    Background Physicians need to inform asymptomatic individuals about personalized outcomes of statin therapy for primary prevention of cardiovascular disease (CVD). However, current prediction models focus on short-term outcomes and ignore the competing risk of death due to other causes. We aimed to predict the potential lifetime benefits with statin therapy, taking into account competing risks. Methods and Findings A microsimulation model based on 5-y follow-up data from the Rotterdam Study, a population-based cohort of individuals aged 55 y and older living in the Ommoord district of Rotterdam, the Netherlands, was used to estimate lifetime outcomes with and without statin therapy. The model was validated in-sample using 10-y follow-up data. We used baseline variables and model output to construct (1) a web-based calculator for gains in total and CVD-free life expectancy and (2) color charts for comparing these gains to the Systematic Coronary Risk Evaluation (SCORE) charts. In 2,428 participants (mean age 67.7 y, 35.5% men), statin therapy increased total life expectancy by 0.3 y (SD 0.2) and CVD-free life expectancy by 0.7 y (SD 0.4). Age, sex, smoking, blood pressure, hypertension, lipids, diabetes, glucose, body mass index, waist-to-hip ratio, and creatinine were included in the calculator. Gains in total and CVD-free life expectancy increased with blood pressure, unfavorable lipid levels, and body mass index after multivariable adjustment. Gains decreased considerably with advancing age, while SCORE 10-y CVD mortality risk increased with age. Twenty-five percent of participants with a low SCORE risk achieved equal or larger gains in CVD-free life expectancy than the median gain in participants with a high SCORE risk. Conclusions We developed tools to predict personalized increases in total and CVD-free life expectancy with statin therapy. The predicted gains we found are small. If the underlying model is validated in an independent cohort, the tools may be

  19. Is rigorous punishment effective? A case study of lifetime license revocation in Taiwan.

    PubMed

    Chang, Hsin-Li; Woo, T Hugh; Tseng, Chien-Ming

    2006-03-01

    This study investigated the effectiveness of administrative lifetime driver's license revocation (ALLR) and its impact on offenders, based on a two-stage survey of 768 offenders. It was found that after ALLR had been imposed, 23.4% of these offenders were still driving almost the same as before, 59.8% drove significantly less frequently, and only 16.8% of the offenders gave up driving completely. The results of logistic regression models showed that offenders' compliance with ALLR was significantly correlated with their personal characteristics (age, income), penalty status (incarceration, duration of ALLR), and the need to drive for working, commuting and shopping. Elderly and low-income offenders were more likely to abide by the ALLR restriction. The application of the generalized estimating equations (GEE) model was used to identify the determinant factors affecting offenders' driving mileage, and to effectively estimate the driving mileage reduction as a result of the ALLR. It was found that ALLR is fairly effective in keeping offenders off the road, but that it may reduce their ability to make a living, resulting in the less fortunate becoming more helpless.

  20. Fluorescence Lifetime Imaging and Intravascular Ultrasound: Co-Registration Study Using Ex Vivo Human Coronaries

    PubMed Central

    Gorpas, Dimitris; Fatakdawala, Hussain; Bec, Julien; Ma, Dinglong; Yankelevich, Diego R.; Qi, Jinyi

    2015-01-01

    Fluorescence lifetime imaging (FLIM) has demonstrated potential for robust assessment of atherosclerotic plaques biochemical composition and for complementing conventional intravascular ultrasound (IVUS), which provides information on plaque morphology. The success of such a bi-modal imaging modality depends on accurate segmentation of the IVUS images and proper angular registration between these two modalities. This paper reports a novel IVUS segmentation methodology addressing this issue. The image preprocessing consisted of denoising, using the Wiener filter, followed by image smoothing, implemented through the application of the alternating sequential filter on the edge separability metric images. Extraction of the lumen/intima and media/adventitia boundaries was achieved by tracing the gray-scale peaks over the A-lines of the IVUS preprocessed images. Cubic spline interpolation, in both cross-sectional and longitudinal directions, ensured boundary smoothness and continuity. The detection of the guide-wire artifact in both modalities is used for angular registration. Intraluminal studies were conducted in 13 ex vivo segments of human coronaries. The IVUS segmentation accuracy was assessed against independent manual tracings, providing 91.82% sensitivity and 97.55% specificity. The proposed methodology makes the bi-modal FLIM and IVUS approach feasible for comprehensive intravascular diagnosis by providing co-registered biochemical and morphological information of atherosclerotic plaques. PMID:25163056

  1. Clay particles - potential of positron annihilation lifetime spectroscopy (PALS) for studying interlayer spacing

    NASA Astrophysics Data System (ADS)

    Fong, N.; Guagliardo, P.; Williams, J.; Musumeci, A.; Martin, D.; Smith, S. V.

    2011-01-01

    Characterisation of clays is generally achieved by traditional methods, such as X-ray diffraction (XRD) and transmission electron microscopy (TEM). However, clays are often difficult to characterise due to lack of long-range order, thus these tools are not always reliable. Because interlayer spacing in clays can be adjusted to house molecules, there is growing interest to use these materials for drug delivery. Positron annihilation lifetime spectroscopy (PALS) was examined as an alternative tool to characterise a series of well-known clays. XRD of two layered double hydroxides; MgAl-LDH and MgGd-LDH, natural hectorite, fluoromica and laponite, and their PALS spectra were compared. XRD data was used to calculate the interlayer d- spacing in these materials and results show a decrease in interlayer spacing as the heavy metal ions are substituted for those of large ionic radii. Similar results were obtained for PALS data. This preliminary study suggests PALS has potential as a routine tool for characterising clay particles. Further work will examine the sensitivity and reliability of PALS to percent of metal doping and hydration in clay microstructure.

  2. Parametric study of transport beam lines for electron beams accelerated by laser-plasma interaction

    SciTech Connect

    Scisciò, M.; Antici, P.; Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L.; Papaphilippou, Y.

    2016-03-07

    In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread.

  3. Parametric study of transport beam lines for electron beams accelerated by laser-plasma interaction

    NASA Astrophysics Data System (ADS)

    Scisciò, M.; Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L.; Papaphilippou, Y.; Antici, P.

    2016-03-01

    In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread.

  4. Study on the lifetime of EPDM seals in nuclear-powered vessels

    NASA Astrophysics Data System (ADS)

    Le Lay, F.

    2013-03-01

    DCNS provides the French Navy with ships and services, including through-life support (TLS). For that activity, the lifetime of seals has to be studied, either because periods between maintenance stops are longer, or because some seals cannot be replaced in short time and without removing big equipments. Among different kinds of seals we studied, we focus on EPDM seals. First of all, we studied their thermal ageing in service, through accelerated ageing procedures and Arrhenius law. Their mechanical properties after 19 and 32 years were estimated. They showed a reasonable evolution. Then, the effects of gamma-radiations were studied at different doses: 10, 20 and 400 kGy combining temperature and radiation and 18, 33 and 250 kGy (only radiation). In both cases, seals were irradiated after thermal ageing. Mechanical properties (compression, tensile, and hardness) were measured at the surface and in the middle of the seals (10×10 mm2 section and 68 mm diameter). In addition, physicochemical tests were performed (TGA and DSC). The results showed that in normal conditions, the properties of the EPDM seals vary a little till 32 years in service (<20% in compression, and <30% in elongation at break in tension). On the other hand, with doses of 250 and 400 kGy, the evolution of the seals is important (+130% compression force). These results are in good concordance with other studies on this kind of polymer, where the dose at which there is a significant modification is about 250 kGy (Madani, 2004; Zaharescu and Podina, 2001).

  5. A Six-Wave Study of the Consistency of Mexican/Mexican American Preadolescents' Lifetime Substance Use Reports

    ERIC Educational Resources Information Center

    Wagstaff, David A.; Kulis, Stephen; Elek, Elvira

    2009-01-01

    In the Fall of 2004, 1,948 5th grade students from Phoenix, AZ enrolled in an evaluation of a school-based, substance use prevention intervention. To assess the consistency of Mexican and Mexican-American students' self-reports of lifetime substance use, the present study analyzed data reported by 1,418 students who reported Mexican ancestry and…

  6. A Six-Wave Study of the Consistency of Mexican/Mexican American Preadolescents' Lifetime Substance Use Reports

    ERIC Educational Resources Information Center

    Wagstaff, David A.; Kulis, Stephen; Elek, Elvira

    2009-01-01

    In the Fall of 2004, 1,948 5th grade students from Phoenix, AZ enrolled in an evaluation of a school-based, substance use prevention intervention. To assess the consistency of Mexican and Mexican-American students' self-reports of lifetime substance use, the present study analyzed data reported by 1,418 students who reported Mexican ancestry and…

  7. Antidepressant use and lifetime history of mental disorders in a community sample: results from the Baltimore Epidemiologic Catchment Area Study.

    PubMed

    Takayanagi, Yoichiro; Spira, Adam P; Bienvenu, O Joseph; Hock, Rebecca S; Carras, Michelle C; Eaton, William W; Mojtabai, Ramin

    2015-01-01

    Past studies have shown that many individuals who use antidepressants have no current or lifetime history of mental disorders. However, recent studies suggest that the one-time retrospective evaluation of mental disorders commonly used in such studies may substantially underestimate the true lifetime prevalence of mental disorders. We examined the prevalence of mental disorders, assessed prospectively over multiple interviews, among individuals currently using antidepressants in a community sample. Using data from the Baltimore Epidemiologic Catchment Area (ECA) Study Wave 1 (1981) through Wave 4 (2004-2005) (N = 1,071), we assessed lifetime prevalence of common mood and anxiety disorders according to DSM-III and DSM-III-R criteria, based on 4 interviews, among participants who reported current antidepressant use. Furthermore, we examined factors associated with current antidepressant use. Thirteen percent of participants at Wave 4 reported currently using antidepressant medications. Among antidepressant users, 69% never met criteria for major depressive disorder (MDD); and 38% never met criteria for MDD, obsessive-compulsive disorder, panic disorder, social phobia, or generalized anxiety disorder in their lifetime. Female gender, Caucasian ethnicity, recent or current physical problems (eg, loss of bladder control, hypertension, and back pain), and recent mental health facility visits were associated with antidepressant use in addition to mental disorders. Many individuals who are prescribed and use antidepressant medications may not have met criteria for mental disorders. Our data indicate that antidepressants are commonly used in the absence of clear evidence-based indications. © Copyright 2015 Physicians Postgraduate Press, Inc.

  8. Rapid fluorescence lifetime estimation with modified phasor approach and Laguerre deconvolution: a comparative study

    NASA Astrophysics Data System (ADS)

    Fereidouni, Farzad; Gorpas, Dimitris; Ma, Dinglong; Fatakdawala, Hussain; Marcu, Laura

    2017-09-01

    Fluorescence lifetime imaging has been shown to serve as a valuable tool for interrogating and diagnosis of biological tissue at a mesoscopic level. The ability to analyze fluorescence decay curves to extract lifetime values in real-time is crucial for clinical translation and applications such as tumor margin delineation or intracoronary imaging of atherosclerotic plaques. In this work, we compare the performance of two popular non-parametric (fit-free) methods for determining lifetime values from fluorescence decays in real-time—the Phasor approach and Laguerre deconvolution. We demonstrate results from simulated and experimental data to compare the accuracy and speed of both methods and their dependence on noise and model parameters.

  9. Antidepressant Use and Lifetime History of Mental Disorders in a Community Sample: Results from the Baltimore Epidemiologic Catchment Area Study

    PubMed Central

    Takayanagi, Yoichiro; Spira, Adam P.; Bienvenu, O. Joseph; Hock, Rebecca S.; Carras, Michelle C.; Eaton, William W.; Mojtabai, Ramin

    2015-01-01

    Objectives Past studies have shown that many individuals who use antidepressants do not have a current or lifetime history of mental disorders. However, recent studies suggest that the one-time retrospective evaluation of mental disorders commonly used in such studies may substantially underestimate the true lifetime prevalence of mental disorders. We examined the prevalence of mental disorders, assessed prospectively over multiple interviews, among individuals currently using antidepressants in a community sample. Methods Using data from the Baltimore Epidemiologic Catchment Area (ECA) Survey Wave 1 (1981) through Wave 4 (2004) (N = 1071), we assessed lifetime prevalence of common mood and anxiety disorders according to the DSM-III and DSM-III-R criteria, based on 4 interviews, among participants who reported current antidepressant use. Furthermore, we examined factors associated with current antidepressant use. Results Thirteen percent of participants at Wave 4 reported currently using antidepressant medications. Among antidepressant users, 69% never met criteria for major depressive disorder (MDD), and 38% never met criteria for MDD, obsessive-compulsive disorder, panic disorder, social phobia, or generalized anxiety disorder in their lifetime. Female gender, Caucasian ethnicity, recent or current physical problems (e.g., loss of bladder control, hypertension and back pain) and recent mental health facility visits were associated with antidepressant use in addition to mental disorders. Conclusions Many individuals who are prescribed and use antidepressant medications may not have met criteria for mental disorders. Our data indicate that antidepressants are commonly used in the absence of clear evidence-based indications. PMID:25188822

  10. Multiple Beam Optical Processing

    DTIC Science & Technology

    1989-12-01

    carrier lifetime (whichever is shorter) exceeds the spot diameter, since in that case the light beams may not be required to overlap. Exception I...incident angle of the switching beam is studied theoretically for the case of pulsed, single- wavelength operation. Both dispersive and absorptive aspects...of the eLalon are included. Simulations predict that differential-gain characteristics can be improved significantly over the normal-incidence case by

  11. Exploring lifetime occupational exposure and SLE flare: a patient-focussed pilot study

    PubMed Central

    Squance, Marline L; Guest, Maya; Reeves, Glenn; Attia, John; Bridgman, Howard

    2014-01-01

    Introduction Environmental effectors, such as ultraviolet radiation exposure, infection and stress, have been established as having a role in exacerbating lupus symptoms. However, unpredictable patterns of flare events still remain a mystery. Occupational effectors have also been suggested as having a contributing role; however, they are not widely researched. In this paper we report a pilot study designed to generate focus areas for future research regarding occupational exposures and systemic lupus erythematosus (SLE). Methods The study explored potential links between exposures and the occurrence of patient-reported flare events in 80 Australian women with SLE (American College of Rheumatology (ACR) criteria classified). Specifically, the study assessed the hypothesis that occupational exposure is associated with significant changes in the likelihood of lupus flares. Lifetime employment history was analysed with the Finnish Job Exposure Matrix (FINJEM), 40 different semiquantified exposure class estimates for a wide number of occupations based on probability of exposure (p≥5%=exposed) were analysed with the construction of negative binomial regression models to test relationships between occupational agents and flare days. A backward stepwise elimination was used to generate a parsimonious model. Results Significant associations were noted for exposure classes of manual handling burden, (p=0.02, incidence rate ratio (IRR) 1.01), Iron (p=0.00, IRR 1.37), wood dust (p=0.00, IRR 3.34) and asbestos (p=0.03, IRR 2.48). Conclusion Exposure assessment results indicated that occupations, such as nursing, with a high manual handling burden, posed increased risk to patients with SLE, however, the greatest risk was associated with wood dust and iron exposure with teachers and specialist labourers. PMID:25379190

  12. Reliability and validity of a telephone questionnaire for estimating lifetime personal sun exposure in epidemiologic studies.

    PubMed

    Kricker, Anne; Vajdic, Claire M; Armstrong, Bruce K

    2005-10-01

    Our Australia-wide case-control study of ocular melanoma diagnosed in 1996 to 1997 needed a short telephone interview on sun exposure. We constructed one by examining data from 700 controls ages 40 to 64 years in the Geraldton Skin Cancer Survey in 1988; they had answered a "whole-of-life" questionnaire in a face-to-face interview. Sun exposure in their first 4 decade years of age best predicted their lifetime annual average sun exposure, so the shortened questionnaire asked about sun exposure in these 4 decade years only. Retesting 60 participants 1 year later with the whole-of-life questionnaire gave an intraclass correlation coefficient of 0.65 (95% confidence interval, 0.48-0.78) for ranked total sun exposure between the two interviews; the intraclass correlation coefficient was higher in men (0.73) than in women (0.54). Correlations were also high between parallel measurements of sun exposure on working days in the decade years and in outdoor occupations throughout life in the telephone interview of the ocular melanoma study (Spearman's R = 0.75) and in another study of non-Hodgkin's lymphoma (R = 0.71). Agreement between simultaneous parallel measures of total exposure (nonworking + working day and recreational + occupational exposure) was slightly weaker and of nonworking day and recreational exposure much weaker. Occupational exposure in women was much less strongly correlated with total exposure than it was in men possibly because of their frequently combined work and family roles, which the questionnaires did not try to separate. Research is needed into how this might be done to improve sun exposure measurement in women.

  13. Beam dynamics studies for the relativistic klystron two-beam accelerator experiment

    SciTech Connect

    Lidia, Steven M.

    2001-06-22

    Two-beam accelerators based upon relativistic klystron s (RK s) have been proposed as power sources for future generation linear electron-positron colliders. These drivers are known to suffer from several transverse beam break-up (BBU) instabilities. A program to study a particular technique (the betatron node scheme ) for ameliorating the high frequency BBU is under way at LBNL. Central to this study are the pillbox RF cavities and RF beam position monitors (BPM s) employed. This paper describes the design, fabrication, and testing of the RF components. Performance details during operation are also discussed.

  14. Lifetime measurements using the Jefferson Lad Load-Lock Electron Gun

    SciTech Connect

    J. Grames; P. Adderley; M. Baylac; J. Brittian; D. Charles; J. Clark; J. Hansknecht; M. Poelker; M. Stutzman; K. Surles-Law

    2000-10-07

    Lifetime measurements of bulk GaAs using a 100 kV load-lock electron gun and beam line were made. Initial tests used anodized samples to study lifetime under various conditions (gun vacuum, laser spot location, activated area). Subsequent tests used a mechanical mask to limit the active area and included improved monitoring of the gun chamber and beam line vacuum pressure. Results of these measurements support claims made at past workshops, namely photocathode lifetime improves when gun vacuum is enhanced and when electron emission from the edge of the photocathode is eliminated. The dependence upon laser spot location is less certain. Tests studying lifetime at higher beam intensity (I ~ 8 mA) have begun.

  15. SU-E-T-304: Study of Secondary Neutrons From Uniform Scanning Proton Beams

    SciTech Connect

    Islam, M; Zheng, Y; Benton, E

    2014-06-01

    Purpose: Secondary neutrons are unwanted byproducts from proton therapy and exposure from secondary radiation during treatment could increase risk of developing a secondary cancer later in a patient's lifetime. The purpose of this study is to investigate secondary neutrons from uniform scanning proton beams under various beam conditions using both measurements and Monte Carlo simulations. Methods: CR-39 Plastic Track Nuclear Detectors (PNTD) were used for the measurement. CR-39 PNTD has tissue like sensitivity to the secondary neutrons but insensitive to the therapeutic protons. In this study, we devised two experimental conditions: a) hollow-phantom; phantom is bored with a hollow cylinder along the direction of the beam so that the primary proton passes through the phantom without interacting with the phantom material, b) cylindrical-phantom; a solid cylinder of diameter close to the beam diameter is placed along the beam path. CR-39 PNTDs were placed laterally inside a 60X20X35 cm3 phantom (hollow-phantom) and in air (cylindrical-phantom) at various angles with respect to the primary beam axis. We studied for three different proton energies (78 MeV, 162 MeV and 226 MeV), using a 4 cm modulation width and 5cm diameter brass aperture for the entire experiment and simulation. A comparison of the experiment was performed using the Monte Carlo code FLUKA. Results: The measured secondary neutron dose equivalent per therapeutic primary proton dose (H/D) ranges from 2.1 ± 0.2 to 25.42 ± 2.3 mSv/Gy for the hollow phantom study, and 2.7 ± 0.3 to 46.4 ± 3.4 mSv/Gy for the cylindrical phantom study. Monte Carlo simulations predicated neutron dose equivalent from measurements within a factor of 5. Conclusion: The study suggests that the production of external neutrons is significantly higher than the production of internal neutrons.

  16. Beams from boltwood: a feasibility study

    Treesearch

    Peter Koch

    1964-01-01

    Previous papers in this series of four have explored technical aspects of converting southern pine boltwood into long laminated beams of uniform high strength. This final discussion examines production and economic aspects of the proposed system.

  17. A comparative study of metabolic state of stem cells during osteogenic and adipogenic differentiations via fluorescence lifetime imaging microscopy

    NASA Astrophysics Data System (ADS)

    Chakraborty, Sandeep; Ou, Meng-Hsin; Kuo, Jean-Cheng; Chiou, Arthur

    2016-10-01

    Cellular metabolic state can serve as a biomarker to indicate the differentiation potential of stem cells into other specialized cell lineages. In this study, two-photon fluorescence lifetime imaging microscopy (2P-FLIM) was applied to determine the fluorescence lifetime and the amounts of the auto-fluorescent metabolic co-factor reduced nicotinamide adenine dinucleotide (NADH) to elucidate the cellular metabolism of human mesenchymal stem cells (hMSCs) in osteogenic and adipogenic differentiation processes. 2P-FLIM provides the free to protein-bound NADH ratio which can serve as the indicator of cellular metabolic state. We measured NADH fluorescence lifetime at 0, 7, and 14 days after hMSCs were induced for either osteogenesis or adipogenesis. In both cases, the average fluorescence lifetime increased significantly at day 14 (P < 0.001), while the ratio of free to protein-bound NADH ratio decreased significantly in 7- days (P < 0.001) and 14-days (P < 0.001). Thus, our results indicated a higher metabolic rate in both osteogenic and adipogenic differentiation processes when compared with undifferentiated hMSCs. This approach may be further utilized to study proliferation efficiency and differentiation potential of stem cells into other specialized cell lineages.

  18. Violent and sexual behaviors and lifetime use of crack cocaine: a population-based study in Brazil.

    PubMed

    Narvaez, Joana C M; Jansen, Karen; Pinheiro, Ricardo T; Kapczinski, Flávio; Silva, Ricardo A; Pechansky, Flávio; Magalhães, Pedro V S

    2014-08-01

    To estimate the prevalence of lifetime use of crack cocaine and to assess associations with violent and sexual behaviors in young adults selected from the general population of Pelotas, Southern Brazil. This cross-sectional population-based study included 1,560 participants aged 18-24 years. The use of alcohol and other substances, including crack cocaine, was assessed using the alcohol, smoking and substance involvement screening test. Other variables included violent behaviors, firearm possession, and sexual risk behaviors. The frequency of antisocial personality disorder was also investigated. Associations were analyzed using a crude model and models adjusted for sex, social class, and the use of snorted cocaine. Lifetime prevalence of crack cocaine use was 2.51 %, and it was higher among males and individuals coming from more vulnerable social classes (D or E). In the final multivariate models, lifetime use of crack cocaine was associated with episodes of aggression and firearm possession, as well as with a higher chance of not having used condom in the last sexual intercourse. In less conservative models, crack cocaine use was associated with other violent and sexual risk behaviors. The strong association observed between lifetime use of crack cocaine and different violent and sexual risk behaviors underscores relevant characteristics of people who use crack cocaine. Improving our understanding of possible causal chains leading to such associations should be a priority in future studies.

  19. A case-cohort study examining lifetime exposure to inorganic arsenic in drinking water and diabetes mellitus.

    PubMed

    James, Katherine A; Marshall, Julie A; Hokanson, John E; Meliker, Jaymie R; Zerbe, Gary O; Byers, Tim E

    2013-05-01

    Consumption of drinking water with high levels of inorganic arsenic (over 500 μg/L) has been associated with type II diabetes mellitus (DM), but previous studies have been inconclusive about risks at lower levels (<100 μg/L). We present a case-cohort study based on individual estimates of lifetime arsenic exposure to examine the relationship between chronic low-level arsenic exposure and risk of DM. This case-cohort study included 141 cases of DM diagnosed between 1984 and 1998 as part of the prospective San Luis Valley Diabetes Study. A comparison sub-cohort of 488 participants was randomly sampled from 936 eligible participants who were disease free at baseline. Individual lifetime arsenic exposure estimates were determined using a methodology that incorporates the use of a structured interview to determine lifetime residence and employment history, geospatial modeling of arsenic concentrations in drinking water, and urine arsenic concentrations. A Cox proportional hazards model with known DM risk factors as time-dependent covariates was used to assess the association between lifetime exposure to inorganic arsenic in drinking water and incident DM. Our findings show a significant association between inorganic arsenic exposure and DM risk (hazard ratio [HR]=1.27, 95%=1.01, 1.59 per 15 μg/L) while adjusting for ethnicity and time varying covariates age, body mass index and physical activity level. Exposure to low-level inorganic arsenic in drinking water is associated with increased risk for type II DM in this population based on a comprehensive lifetime exposure assessment. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Technology integration box beam failure study

    NASA Technical Reports Server (NTRS)

    Shuart, Mark J.; Ambur, Damodar R.; Davis, D. D., Jr.; Davis, R. C.; Farley, G. L.; Lotts, C. G.; Wang, J. T.

    1992-01-01

    The objective of this paper is to describe current results from an on-going study of the mechanisms that led to the failure of the TIBB. Experimental and analytical results are presented. Experimental results include load, strain, and deflection data for the TIBB (Technology Integration Box Beam). An analytical investigation was conducted to compliment the experimental investigation and to gain additional insight into the TIBB structural response. Analytical results include strain and deflection results from a global analysis of the TIBB. A local analysis of the failure region is being completed. These analytical results are validated through comparisons with the experimental results from the TIBB tests. The experimental and analytical results from the TIBB tests are used to determine a sequence of events that may have resulted in failure of the TIBB. A potential cause of failure is high stresses in a stiffener runout region. Typical analytical results are presented for a stiffener runout specimen that is being defined to simulate the TIBB failure mechanisms. The results of this study are anticipated to provide better understanding of potential failure mechanisms in composite aircraft structures, to lead to future design improvements, and to identify needed analytical tools for design and analysis.

  1. Direct Correlation between Ionic Liquid Transport Properties and Ion Pair Lifetimes: A Molecular Dynamics Study.

    PubMed

    Zhang, Yong; Maginn, Edward J

    2015-02-19

    Self-diffusivities as a function of temperature were computed for 29 different ionic liquids (ILs) covering a wide variety of cation and anion classes. Ideal ionic conductivities (σNE) were estimated from the self-diffusivities via the Nernst-Einstein relation. The ion pair (IP) lifetimes (τIP) and ion cage (IC) lifetimes (τIC) of each IL were also computed. A linear relationship between the calculated self-diffusivities and the inverse of IP or IC lifetimes was observed. A similar inverse linear relationship was also observed for ideal ionic conductivity. These relationships were found to be independent of temperature and the nature of the IL. These observations connect macroscopic dynamic properties with local atomic-level motions and strongly suggest that the dynamics of ILs are governed by a universal IP or IC forming and breaking mechanism. Thus, in order to design an ionic liquid with enhanced dynamics, one should consider how to minimize IP or IC lifetimes.

  2. Results and Systematic Studies of the UCN Lifetime Experiment at NIST

    NASA Astrophysics Data System (ADS)

    Huffer, Craig Reeves

    The neutron beta-decay lifetime is important in understanding weak interactions in the framework of the Standard Model, and it is an input to nuclear astrophysics and Big Bang Nucleosynthesis. Current measurements of the neutron beta-decay lifetime disagree, which has motivated additional experiments that are sensitive to different sets of systematic effects. An effort continues at the NIST Center for Neutron Research (NCNR) to improve the statistical and systematic limitations of an experiment to measure the neutron beta-decay lifetime using magnetically trapped UCN. In the experiment, a monoenergetic 0:89 nm cold neutron is incident on a superfluid 4He target within the minimum field region of an Ioffe type magnetic trap. Some of the neutrons are subsequently downscattered by single phonons in the helium to low energies (≈ 200 neV), and those in the appropriate spin state become trapped. The inverse process, upscattering of UCN, is suppressed by the low phonon density in the < 300 mK helium. When the neutron decays, the energetic electron creates EUV scintillation light, which is down-converted and transported out of the cell to PMTs operated at room temperature. With this method, the decay of the UCN population can be monitored in situ. The apparatus, analysis, data, and systematics will be discussed. After accounting for the systematic effects the measured lifetime disagrees with the current PDG mean neutron beta-decay lifetime by about 9 of our standard deviations, which is a strong indication of unaccounted for systematic effects. Additional 3He contamination will be shown to be the most likely candidate for the additional systematic shift, which motivated the commissioning and initial operation of a heat flush purifier for purifying additional 4He. This work ends with a description of the 4He purifier and its performance.

  3. Recent study of beam stability in the PSR

    SciTech Connect

    Wang, T.S.F.; Cooper, R.; Fitzgerald, D.; Frankle, S.; Hardek, T.; Hutson, R.; Macek, R.; Ohmori, C.; Plum, M.; Thiessen, H.; Wilkinson, C.; Colton, E.; Neuffer, D.; Rees, G.

    1993-06-01

    A fast transverse instability with beam loss has been observed in the 800 MeV Los Alamos Pro Ring (PSR) when the injected beam intensity reaches 2 - 4 {times} 10{sup 13} protons per pulse. Previous observations in that the instability is most likely driven by electrons trapped within the proton beam. Theoretical study shown that beam leakage into the inter-bunch gap leads to electron trapping. Recent experiments were carried out by using the newly implemented ``pinger`` and by varying the machine transition gamma to explore further the ``e-p`` instability and the nature of the instability. This paper summarizes some of these recent experimental results and theoretical studies.

  4. Recent study of beam stability in the PSR

    SciTech Connect

    Wang, T.S.F.; Cooper, R.; Fitzgerald, D.; Frankle, S.; Hardek, T.; Hutson, R.; Macek, R.; Ohmori, C.; Plum, M.; Thiessen, H.; Wilkinson, C. ); Colton, E. ); Neuffer, D. ); Rees, G. )

    1993-01-01

    A fast transverse instability with beam loss has been observed in the 800 MeV Los Alamos Pro Ring (PSR) when the injected beam intensity reaches 2 - 4 [times] 10[sup 13] protons per pulse. Previous observations in that the instability is most likely driven by electrons trapped within the proton beam. Theoretical study shown that beam leakage into the inter-bunch gap leads to electron trapping. Recent experiments were carried out by using the newly implemented pinger'' and by varying the machine transition gamma to explore further the e-p'' instability and the nature of the instability. This paper summarizes some of these recent experimental results and theoretical studies.

  5. Simulation Studies of Beam-Beam Effects of a Ring-Ring Electron-Ion Collider Based on CEBAF

    SciTech Connect

    Yuhong Zhang,Ji Qiang

    2009-05-01

    The collective beam-beam effect can potentially cause a rapid growth of beam sizes and reduce the luminosity of a collider to an unacceptably low level. The ELIC, a proposed ultra high luminosity electron-ion collider based on CEBAF, employs high repetition rate crab crossing colliding beams with very small bunch transverse sizes and very short bunch lengths, and collides them at up to 4 interaction points with strong final focusing. All of these features can make the beam-beam effect challenging. In this paper, we present simulation studies of the beam-beam effect in ELIC using a self-consistent strong-strong beam-beam simulation code developed at Lawrence Berkeley National Laboratory. This simulation study is used for validating the ELIC design and for searching for an optimal parameter set.

  6. Accuracy of Reports of Lifetime Mental and Physical Disorders: results from the Baltimore Epidemiological Catchment Area Study

    PubMed Central

    Takayanagi, Yoichiro; Spira, Adam P.; Roth, Kimberly B.; Gallo, Joseph J.; Eaton, William W.; Mojtabai, Ramin

    2014-01-01

    Importance Our understanding of how mental and physical disorders are associated and contribute to health outcomes in populations depends on accurate ascertainment of the history of these disorders. Recent studies have identified substantial discrepancies in the prevalence of mental disorders among adolescents and young adults depending on whether the estimates are based on retrospective reports or multiple assessments over time. It is unknown whether such discrepancies are also seen in mid to late life. Furthermore, no previous studies have compared lifetime prevalence estimates of common physical disorders such as diabetes and hypertension ascertained by prospective cumulative estimates vs. retrospective estimates. Objective To examine the lifetime prevalence estimates of mental and physical disorders during mid to late life using both retrospective and cumulative evaluations. Design Prospective population-based survey with 4 waves of interviews. Setting Community residents in Baltimore City, Maryland. Participants Volunteers who participated in the Baltimore Epidemiologic Catchment Area (ECA) Survey wave 1 (1981) through wave 4 (2004) follow-up data (N = 1,071). Main outcome measures Lifetime prevalence of selected mental and physical disorders at wave 4 (2004), according to both retrospective data and cumulative evaluations based on 4 interviews from wave 1 to wave 4. Results Retrospective evaluations substantially underestimated the lifetime prevalence of mental disorders as compared with cumulative evaluations. The lifetime prevalence estimates ascertained by retrospective and cumulative evaluations were 4.5% vs. 13.1%, respectively, for major depression, 0.6% vs. 7.1% for obsessive-compulsive disorder, 2.5% vs. 6.7% for panic disorder, 12.6% vs. 25.3% for social phobia, 9.1% vs. 25.9% for alcohol abuse/dependence, and 6.7% vs. 17.6% for drug abuse/dependence. In contrast, retrospective lifetime prevalence estimates of physical disorders ascertained at wave 4

  7. Accuracy of reports of lifetime mental and physical disorders: results from the Baltimore Epidemiological Catchment Area study.

    PubMed

    Takayanagi, Yoichiro; Spira, Adam P; Roth, Kimberly B; Gallo, Joseph J; Eaton, William W; Mojtabai, Ramin

    2014-03-01

    Our understanding of how mental and physical disorders are associated and contribute to health outcomes in populations depends on accurate ascertainment of the history of these disorders. Recent studies have identified substantial discrepancies in the prevalence of mental disorders among adolescents and young adults depending on whether the estimates are based on retrospective reports or multiple assessments over time. It is unknown whether such discrepancies are also seen in midlife to late life. Furthermore, no previous studies have compared lifetime prevalence estimates of common physical disorders such as diabetes mellitus and hypertension ascertained by prospective cumulative estimates vs retrospective estimates. To examine the lifetime prevalence estimates of mental and physical disorders during midlife to late life using both retrospective and cumulative evaluations. Prospective population-based survey (Baltimore Epidemiologic Catchment Area Survey) with 4 waves of interviews of 1071 community residents in Baltimore, Maryland, between 1981 and 2005. Lifetime prevalence of selected mental and physical disorders at wave 4 (2004-2005), according to both retrospective data and cumulative evaluations based on 4 interviews from wave 1 to wave 4. RESULTS Retrospective evaluations substantially underestimated the lifetime prevalence of mental disorders as compared with cumulative evaluations. The respective lifetime prevalence estimates ascertained by retrospective and cumulative evaluations were 4.5% vs. 13.1% for major depressive disorder, 0.6% vs. 7.1% for obsessive-compulsive disorder, 2.5% vs. 6.7% for panic disorder, 12.6% vs. 25.3% for social phobia, 9.1% vs. 25.9% for alcohol abuse or dependence, and 6.7% vs. 17.6% for drug abuse or dependence. In contrast, retrospective lifetime prevalence estimates of physical disorders ascertained at wave 4 were much closer to those based on cumulative data from all 4 waves. The respective prevalence estimates ascertained

  8. Technology integration box beam failure study

    NASA Technical Reports Server (NTRS)

    Shuart, M. J.; Ambur, Damodar R.; Davis, D. D., Jr.; Davis, R. C.; Farley, G. L.; Lotts, C. G.; Wang, J. T.

    1993-01-01

    Composite structures have the potential to be cost-effective, structurally efficient primary aircraft structures. The Advanced Composites Technology (ACT) Program has the goal to develop the technology to exploit this potential for heavily loaded aircraft structures. As part of the ACT Program, Lockheed Aeronautical Systems Company completed the design and fabrication of the Technology Integration Box Beam (TIBB). The TIBB is an advanced composite prototype structure for the center wing section of the C-130 aircraft. Lockheed subjected the TIBB to downbending, upbending, torsion and combined upbending and torsion load conditions to verify the design. The TIBB failed at 83 percent of design ultimate load for the combined upbending and torsion load condition. The objective of this paper is to describe the mechanisms that led to the failure of the TIBB. The results of a comprehensive analytical and experimental study are presented. Analytical results include strain and deflection results from both a global analysis of the TIBB and a local analysis of the failure region. These analytical results are validated by experimental results from the TIBB tests. The analytical and experimental results from the TIBB tests are used to determine a sequence of events that resulted in failure of the TIBB. A potential cause of failure is high stresses in a stiffener runout region. Analytical and experimental results are also presented for a stiffener runout specimen that was used to simulate the TIBB failure mechanisms.

  9. Molecular beam studies of reaction dynamics

    SciTech Connect

    Lee, Y.T.

    1993-12-01

    The major thrust of this research project is to elucidate detailed dynamics of simple elementary reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation.

  10. Molecular beam studies of reaction dynamics

    SciTech Connect

    Lee, Y.T.

    1990-03-01

    The major thrust of this research project is to elucidate detailed dynamics of simple reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation. 34 refs.

  11. Molecular beam studies of reaction dynamics

    SciTech Connect

    Lee, Yuan T.

    1991-03-01

    The major thrust of this research project is to elucidate detailed dynamics of simple elementary reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation.

  12. Numerical study of neutron beam divergence in a beam-fusion scenario employing laser driven ions

    NASA Astrophysics Data System (ADS)

    Alejo, A.; Green, A.; Ahmed, H.; Robinson, A. P. L.; Cerchez, M.; Clarke, R.; Doria, D.; Dorkings, S.; Fernandez, J.; McKenna, P.; Mirfayzi, S. R.; Naughton, K.; Neely, D.; Norreys, P.; Peth, C.; Powell, H.; Ruiz, J. A.; Swain, J.; Willi, O.; Borghesi, M.; Kar, S.

    2016-09-01

    The most established route to create a laser-based neutron source is by employing laser accelerated, low atomic-number ions in fusion reactions. In addition to the high reaction cross-sections at moderate energies of the projectile ions, the anisotropy in neutron emission is another important feature of beam-fusion reactions. Using a simple numerical model based on neutron generation in a pitcher-catcher scenario, anisotropy in neutron emission was studied for the deuterium-deuterium fusion reaction. Simulation results are consistent with the narrow-divergence (∼ 70 ° full width at half maximum) neutron beam recently served in an experiment employing multi-MeV deuteron beams of narrow divergence (up to 30° FWHM, depending on the ion energy) accelerated by a sub-petawatt laser pulse from thin deuterated plastic foils via the Target Normal Sheath Acceleration mechanism. By varying the input ion beam parameters, simulations show that a further improvement in the neutron beam directionality (i.e. reduction in the beam divergence) can be obtained by increasing the projectile ion beam temperature and cut-off energy, as expected from interactions employing higher power lasers at upcoming facilities.

  13. SUMMARY OF BEAM BEAM OBSERVATIONS DURING STORES IN RHIC.

    SciTech Connect

    FISCHER,W.

    2003-05-19

    During stores, the beam-beam interaction has a significant impact on the beam and luminosity lifetimes in RHIC. This was observed in heavy ion, and even more pronounced in proton collisions. Observations include measurements of beam-beam induced tune shifts, lifetime and emittance growth measurements with and without beam-beam interaction, and background rates as a function of tunes. In addition, RHIC is currently the only hadron collider in which strong-strong beam-beam effects can be seen. Coherent beam-beam modes were observed, and suppressed by tune changes. In this article we summarize the most important beam-beam observations made during stores so far.

  14. A feasibility study of multiplexing parallel beam.

    PubMed

    Ma, Jiayi; Zhao, Jingwu; Shi, Xiaodong; Huang, Runshen

    2013-05-01

    Single-photon emission computed tomography (SPECT) is a suitable tool for clinically localizing deep-sited tumors; SPECT with high spatial resolution has the ability to localize deep-sited tumors precisely. However, because of its poor sensitivity, in China SPECT now only plays a complementary role. To improve the sensitivity of the parallel beam collimator mainly used in China, a multiplexing parallel beam collimator is proposed, which can improve sensitivity while maintaining higher spatial resolution by using theoretical prediction and Monte Carlo simulation. The improved sensitivity-to-spatial resolution ratio has an optimal value. In addition, a set of gamma ray channels, introduced only in the transverse direction, did not have any effect in the axial direction. In the transverse direction, the projection data are the sum of the parallel beam and two oblique parallel beams. From visual assessment obtained using computer simulations with equal sensitivity, the reconstructed image at deep-sited was noticeably better than that with the high sensitivity parallel beam.

  15. Association of Educational Attainment With Lifetime Risk of Cardiovascular Disease: The Atherosclerosis Risk in Communities Study.

    PubMed

    Kubota, Yasuhiko; Heiss, Gerardo; MacLehose, Richard F; Roetker, Nicholas S; Folsom, Aaron R

    2017-08-01

    Estimates of lifetime risk may help raise awareness of the extent to which educational inequalities are associated with risk of cardiovascular disease (CVD). To estimate lifetime risks of CVD according to categories of educational attainment. Participants were followed from 1987 through December 31, 2013. All CVD events (coronary heart disease, heart failure, and stroke) were confirmed by physician review and International Classification of Diseases codes. A total of 13 948 whites and African Americans who were 45 to 64 years old and free of CVD at baseline were included from 4 US communities (Washington County, Maryland; Forsyth County, North Carolina; Jackson, Mississippi; and suburbs of Minneapolis, Minnesota). The data analysis was performed from June 7 to August 31, 2016. Educational attainment. We used a life table approach to estimate lifetime risks of CVD from age 45 through 85 years according to educational attainment. We adjusted for competing risks of death from underlying causes other than CVD. The sample of 13 948 participants was 56% female and 27% African American. During 269 210 person-years of follow-up, we documented 4512 CVD events and 2401 non-CVD deaths. Educational attainment displayed an inverse dose-response relation with cumulative risk of CVD, which became evident in middle age, with the most striking gap between those not completing vs completing high school. In men, lifetime risks of CVD were 59.0% (95% CI, 54.0%-64.1%) for grade school, 52.5% (95% CI, 47.7%-56.8%) for high school education without graduation, 50.9% (95% CI, 47.3%-53.9%) for high school graduation, 47.2% (95% CI, 41.5%-52.5%) for vocational school, 46.4% (95% CI, 42.8%-49.6%) for college with or without graduation, and 42.2% (95% CI, 36.6%-47.0%) for graduate/professional school; in women, 50.8% (95% CI, 45.7%-55.8%), 49.3% (95% CI, 45.1%-53.1%), 36.3% (95% CI, 33.4%-39.1%), 32.2% (95% CI, 26.0%-37.3%), 32.8% (95% CI, 29.1%-35.9%), and 28.0% (95% CI, 21

  16. ATOMIC BEAM STUDIES IN THE RHIC H-JET POLARIMETER.

    SciTech Connect

    MAKDISI,Y.; ZELENSKI,A.; GRAHAM,D.; KOKHANOVSKI,S.; MAHLER,G.; NASS,A.; RITTER,J.; ZUBETS,V.; ET AL.

    2005-01-28

    The results of atomic beam production studies are presented. Improved cooling of the atoms before jet formation in the dissociator cold nozzle apparently reduces the atomic beam velocity spread and improves beam focusing conditions. A carefully designed sextupole separating (and focusing) magnet system takes advantage of the high brightness source. As a result a record beam intensity of a 12.4 {center_dot} 10{sup 16} atoms/s was obtained within 10 mm acceptance at the collision point. The results of the polarization dilution factor measurements (by the hydrogen molecules at the collision point) are also presented.

  17. Experimental Studies of Ion Beam Neutralization: Preliminary Results

    SciTech Connect

    Ding, N.; Polansky, J.; Downey, R.; Wang, J.

    2011-05-20

    A testing platform is designed to study ion beam neutralization in the mesothermal, collisionless region. In the experimental setup, argon neutrals were ionized in a microwave cavity and accelerated by a plasma lens system which was biased to 2500 V above the system ground. Electrons were boiled off from two hot tungsten filaments to neutralize the ion beam. The plasma is diagnosed using Langmuir probe and Faraday probe. A 3-D traversing system and a complete data acquisition loop were developed to efficiently measure 3-D beam profile. Preliminary measurements of beam profiles are presented for different operating conditions.

  18. Alignment Sensitivity Study of the St. ANA Beam Line

    NASA Astrophysics Data System (ADS)

    Gervais, Michelle; Couder, Manoel; Jung, Hyo Soon; Setoodehnia, Kiana

    2014-09-01

    The St. ANA (STable Accelerator for Nuclear Astrophysics) accelerator is being prepared for use with the St. George recoil mass separator. The accelerator is in working condition for use in direct kinematic experiments but the St. George separator works with inverse kinematics and requires a highly controlled beam restricted by severe position and divergence parameters that are not achieved at the present time. A systematic sensitivity study was conducted using a simulation of the beam line in order to assess the impact of a misalignment in each optical element or in the beam itself. Tests were done with the beam to analyze how the beam behaves at various points in the line and to compare this data with simulation results to determine possible causes of misalignment. The results of these tests and simulations are that the beam characteristics are now better understood and the possible causes of the limitations have been narrowed down. The St. ANA (STable Accelerator for Nuclear Astrophysics) accelerator is being prepared for use with the St. George recoil mass separator. The accelerator is in working condition for use in direct kinematic experiments but the St. George separator works with inverse kinematics and requires a highly controlled beam restricted by severe position and divergence parameters that are not achieved at the present time. A systematic sensitivity study was conducted using a simulation of the beam line in order to assess the impact of a misalignment in each optical element or in the beam itself. Tests were done with the beam to analyze how the beam behaves at various points in the line and to compare this data with simulation results to determine possible causes of misalignment. The results of these tests and simulations are that the beam characteristics are now better understood and the possible causes of the limitations have been narrowed down. Project advisor

  19. H line; a beam line for fundamental physics study

    NASA Astrophysics Data System (ADS)

    Kawamura, Naritoshi; Toyoda, Akihisa; Aoki, Masaharu; Shimomura, Koichiro; Mibe, Tsutomu; Nakatsugawa, Yohei; Otani, Masashi; Saito, Naohito; Miyake, Yasuhiro

    2014-12-01

    The muon facility, J-PARC (Muon Science Establishment; MUSE), has been operating since the first beam in 2008. Starting with a 200 kW proton beam, a beam intensity of 3 × 106 muons/s was reached in 2009 which was the most intense pulsed muon beam in the world. From the 2 cm thick graphite target, four secondary muon beam lines are designed to be extracted. Three beam lines currently exist, the first being operational and the other two undergoing commissioning. The fourth and the last beam line, the H line, is planned to be constructed. This new beam line is designed to have a large acceptance, provides the ability to tune the momentum, and use a kicker magnet and/or a Wien filter. The H line is designed to provide an intense beam of 108 surface muons/s for fundamental physics studies to observe new physics beyond the standard model. Such studies require high statistics and they need to occupy the experimental areas for a relatively long period.

  20. Study of excitation transfer in laser dye mixtures by direct measurement of fluorescence lifetime

    NASA Technical Reports Server (NTRS)

    Lin, C.; Dienes, A.

    1973-01-01

    By directly measuring the donor fluorescence lifetime as a function of acceptor concentration in the laser dye mixture Rhodamine 6G-Cresyl violet, we found that the Stern-Volmer relation is obeyed, from which the rate of excitation transfer is determined. The experimental results indicate that the dominant mechanism responsible for the efficient excitation transfer is that of resonance transfer due to long range dipole-dipole interaction.

  1. FRC Lifetime Studies for the Field Reversed Configuration Heating Experiment (FRCHX)

    DTIC Science & Technology

    2011-06-01

    sources , gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden...hardware are being developed to record images in the VUV spectrum, as these will provide a view of the hotter regions of the plasma. The spectrometers in...no change in FRC lifetime. Scans of the PI zero-crossing have been limited, as well, and have been limited to tests performed with the RF source

  2. Transitions and relaxations in gamma-irradiated polypropylene studied by positron annihilation lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Djourelov, N.; Suzuki, T.; Shantarovich, V. P.; Dobreva, T.; Ito, Y.

    2005-01-01

    The changes in the relaxation and transition temperatures in PP due to gamma irradiation in a vacuum were measured by means of positron annihilation lifetime spectroscopy. It was shown that the gamma and beta relaxation temperatures, as well as the melting point follow the changes in the crystallinity with the irradiation dose. For the glass transition temperatures and premelting point, after irradiation dose of 88 kGy, an inverse of the changes was observed.

  3. Simulation study on the emittance compensation of off-axis emitted beam in RF photoinjector

    NASA Astrophysics Data System (ADS)

    Huang, Rui-Xuan; Mitchell, Chad; Jia, Qi-Ka; Papadopoulos, Christos; Sannibale, Fernando

    2016-11-01

    To make full use of the photocathode material and improve its quantum efficiency lifetime, it can be necessary to operate the laser away from the cathode center in photoinjectors. In RF guns, the off-axis emitted beam will see a time-dependent RF effect, which would generate a significant growth in transverse emittance. It has been demonstrated that such an emittance growth can be almost completely compensated by orienting the beam on a proper orbit in the downstream RF cavities along the injector [1]. In this paper we analyze in detail the simulation techniques used in reference [1] and the issues associated with them. The optimization of photoinjector systems involving off-axis beams is a challenging problem. To solve this problem, one needs advanced simulation tools including both genetic algorithms and an efficient algorithm for 3D space charge. In this paper, we report on simulation studies where the two codes ASTRA and IMPACT-T are used jointly to overcome these challenges, in order to optimize a system designed to compensate for the emittance growth in a beam emitted off axis. Supported by National Nature Science Foundation of China (11375199), and Chinese Scholarship Council

  4. Beam Dynamics Studies for the SPARC Project

    SciTech Connect

    Ferrario, M.; Biagini, Maria E.; Boscolo, M.; Fusco, V.; Guiducci, S.; Migliorati, M.; Serafini, L.; Vaccarezza, C.; Bartolini, R.; Giannessi, L.; Quattromini, M.; Ronsivalle, C.; Limborg, C.G.; /Unlisted /Unlisted /ENEA, Frascati /SLAC

    2008-03-17

    The aim of the SPARC project, is to promote an R&D activity oriented to the development of a high brightness photoinjector to drive SASE-FEL experiments. We discuss in this paper the status of the beam dynamics simulation activities.

  5. Atom beam surface interaction studies: Experimental system development

    NASA Technical Reports Server (NTRS)

    Gregory, J. C.

    1973-01-01

    Quantitative deposition by standard techniques of adsorbates containing C and Si onto selected substrates is studied. The interaction kinetics of a beam of oxygen, nitrogen, or hydrogen atoms of known flux are investigated by Auger electron spectroscopy and LEED. Desborbed molecules will be analyzed by mass spectroscopy using modulated beam techniques. Experimental conditions permitting, two sets of measurements will be correlated.

  6. Effects of a polybrominated biphenyl mixture in the rat and mouse. II. Lifetime study.

    PubMed

    Gupta, B N; McConnell, E E; Moore, J A; Haseman, J K

    1983-03-30

    This study was undertaken to characterize the long-term toxic and carcinogenic potential of a polybrominated biphenyl (PBB) mixture in rats and mice of both sexes. Fischer 344 rats and B6C3F1 mice were given 125 po doses of PBB over a 6-month period at 0 (control), 0.1, 0.3, 1.0, 3.0, and 10.0 mg/kg body weight/day (5 days/week) and observed for an additional 23 months for rats and 24 months for mice (lifetime observation). The treatments (0.3 mg/kg or higher dosages) shortened the survival time in male rats whereas no such effect was observed in treated females. There was also evidence of shortened survival time in mice treated with 10.0 mg/kg PBB. As observed by uv light, hepatic porphyrin markedly increased at the 6-month observation, then tended to decrease, primarily in mice, following cessation of exposure. Significantly higher incidences of atypical hepatocellular foci, neoplastic nodules, hepatocellular carcinomas, and cholangiocarcinomas were observed in exposed rats. The incidence of hepatocellular carcinoma was also increased in both male (95%) and female (88%) mice (highest dose level) compared with control male (48%) and female (0%) mice. The incidence of hepatic neoplasms appeared to be dose dependent in both species. Liver tumors were observed primarily in those groups of animals to which PBB was given in doses sufficient to induce readily observable hepatic toxicity. Under the conditions of this experiment, polybrominated biphenyl mixture (Firemaster FF-1) was carcinogenic for Fischer 344 rats and B6C3F1 mice of both sexes. Lesions included neoplastic nodules, hepatocellular carcinomas, and cholangiocarcinomas in rats and hepatocellular carcinomas in mice. Other manifestations of toxicity included porphyrogenic effects and hepatotoxicity. A significantly higher incidence of chronic progressive nephropathy was observed in male rats of the 1.0, 3.0, and 10.0 mg/kg dosage groups when compared with control males. Gastric ulcers and hyperplastic

  7. Long-Range And Head-On Beam-Beam Compensation Studies in RHIC With Lessons for the LHC

    SciTech Connect

    Fischer, W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G.; Dorda, U.; Koutchouk, J.P.; Sterbini, G.; Zimmermann, F.; Kim, H.J.; Sen, T.; Shiltsev, V.; Valishev, A.; Qiang, J.; Kabel, A.; /SLAC

    2011-11-28

    Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are are also important consideration for the LHC upgrades. To mitigate long-range effects, current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. Electron lenses were proposed for both RHIC and the LHC to reduce the head-on beam-beam effect. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.

  8. Long-range and head-on beam-beam compensation studies in RHIC with lessons for the LHC

    SciTech Connect

    Fischer, W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G.; Dorda, U.; Koutchouk, J.-P.; Sterbini, G.; Zimmermann, F.; Kim, H.-J.; Sen, T.; Shiltsev, V.; Valishev, A.; Qiang, J.; Kabel, A.

    2009-01-12

    Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are also important consideration for the LHC upgrades. To mitigate long-range effects, current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. Electron lenses were proposed for both RHIC and the LHC to reduce the head-on beam-beam effect. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.

  9. Long-range and head-on beam-beam compensation studies in RHIC with lessons for the LHC

    SciTech Connect

    Fischer,W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G.; Dorda, U.; Koutchouk, J. -P.; Sterbini, G.; Zimmermann, F.; Kim, H. -J.; Sen, T.; Shiltsev, V.; Valishev, A.; Qiang, J.; Kabel, A.

    2008-11-24

    Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are also important consideration for the LHC upgrades. To mitigate long-range effects current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. To reduce the head-on beam-beam effect electron lenses were proposed for both RIDC and the LHC. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.

  10. Crossed molecular beam studies of atmospheric chemical reaction dynamics

    SciTech Connect

    Zhang, Jingsong

    1993-04-01

    The dynamics of several elementary chemical reactions that are important in atmospheric chemistry are investigated. The reactive scattering of ground state chlorine or bromine atoms with ozone molecules and ground state chlorine atoms with nitrogen dioxide molecules is studied using a crossed molecular beams apparatus with a rotatable mass spectrometer detector. The Cl + O3 → ClO + O2 reaction has been studied at four collision energies ranging from 6 kcal/mole to 32 kcal/mole. The derived product center-of-mass angular and translational energy distributions show that the reaction has a direct reaction mechanism and that there is a strong repulsion on the exit channel. The ClO product is sideways and forward scattered with respect to the Cl atom, and the translational energy release is large. The Cl atom is most likely to attack the terminal oxygen atom of the ozone molecule. The Br + O3 → ClO + O2 reaction has been studied at five collision energies ranging from 5 kcal/mole to 26 kcal/mole. The derived product center-of-mass angular and translational energy distributions are quite similar to those in the Cl + O3 reaction. The Br + O3 reaction has a direct reaction mechanism similar to that of the Cl + O3 reaction. The electronic structure of the ozone molecule seems to play the central role in determining the reaction mechanism in atomic radical reactions with the ozone molecule. The Cl + NO2 → ClO + NO reaction has been studied at three collision energies ranging from 10.6 kcal/mole to 22.4 kcal/mole. The center-of-mass angular distribution has some forward-backward symmetry, and the product translational energy release is quite large. The reaction proceeds through a short-lived complex whose lifetime is less than one rotational period. The experimental results seem to show that the Cl atom mainly attacks the oxygen atom instead of the nitrogen atom of the NO2

  11. Comparative study of the beam-width spreading of partially coherent Hermite-sinh-Gaussian beams in atmospheric turbulence.

    PubMed

    Li, Jinhong; Yang, Ailin; Lü, Baida

    2008-11-01

    Taking the partially coherent Hermite-sinh-Gaussian (H-ShG) beam as a more general type of partially coherent beams, a comparative study of the beam-width spreading of partially coherent H-ShG beams in atmospheric turbulence is performed by using the relative width, normalized beam width, and turbulence length. It is shown that the relative width versus the beam parameters, such as the spatial correlation length sigma(0), beam orders m, n, Sh-part parameter Omega(0), and waist width w(0), provides a simple and intuitive insight into the beam-width spreading of partially coherent H-ShG beams in turbulence, and the results are consistent with those using the turbulence length. The validity of our results is interpreted physically.

  12. Neutral beam source commercialization study. Final report

    SciTech Connect

    King, H.J.

    1980-06-01

    The basic tasks of this Phase II project were to: generate a set of design drawings suitable for quantity production of sources of this design; fabricate a functional neutral beam source incorporating as many of the proposed design changes as proved feasible; and document the procedures and findings developed during the contract. These tasks have been accomplished and represent a demonstrated milestone in the industrialization of this complete device.

  13. Properties of DNA-polyintercalating drugs studied by fluorescence lifetime techniques

    NASA Astrophysics Data System (ADS)

    Winter, Stefan; Popa, Liviu M.

    1995-01-01

    Dimers of the fluorescent dye Oxazole Yellow (YOYO and POPO) are used for high sensitive DNA detection in gel electrophoresis. Upon binding to DNA they show a 3000 to 5000 fold enhancement of fluorescence. The binding constant of those dimers to dsDNA is between 108 M-1 and 109 M-1. This is due to the dye's ability to bisintercalate between adjacent DNA basepairs. We investigated the occurring forms of intercalation of YOYO to dsDNA in solutions of different ionic strength by fluorescence lifetime methods.

  14. Lifetime studies in H/sub 2//Br/sub 2/ fuel cells

    SciTech Connect

    Barna, G.G.; Frank, S.N.; Teherani, T.H.; Weedon, L.D.

    1984-09-01

    A fully computerized system has been set up for the life testing of H/sub 2/ electrodes in 48% HBr, and of H/sub 2//Br/sub 2/ fuel cells. Given a fuel cell design with dry H/sub 2/ and no anolyte loop, the prime parameters influencing the operating lifetime are the hydrophobicity of the anode and the electrolyte transport property of the membrane. A systematic optimization of all the parameters has generated fuel cells that have operated for 10,000h at 2 A/in./sup 2/, with no significant degradation.

  15. Measurement requirements and techniques for degradation studies and lifetime prediction testing of photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Noel, G. T.; Sliemers, F. A.; Derringer, G. C.; Wood, V. E.; Wilkes, K. E.; Gaines, G. B.; Carmichael, D. C.

    1978-01-01

    Tests of weathering and aging behavior are being developed to characterize the degradation and predict the lifetimes of low-cost photovoltaic arrays. Environmental factors which affect array performance include UV radiation, thermal energy, water, oxygen (generally involved in synergistic effects with UV radiation or high temperatures), physical stress, pollutants (oxides of nitrogen, sulfur dioxide and ozone), abrasives and dirt. A survey of photovoltaic array testing has shown the need to establish quantitative correlations between certain measurable properties (carbonyl formation, glass transition temperature, and molecular weight change) and modes of degradation and failure.

  16. BEAM-BEAM 2003 SUMMARY.

    SciTech Connect

    FISCHER,W.SEN,T.

    2003-05-19

    This paper summarizes the presentations and discussions of the Beam-Beam'03 workshop, held in Montauk, Long Island, from May 19 to 23, 2003. Presentations and discussions focused on halo generation from beam-beam interactions; beam-beam limits, especially coherent limits and their effects on existing and future hadron colliders; beam-beam compensation techniques, particularly for long-range interactions; and beam-beam study tools in theory, simulation, and experiment.

  17. A six-wave study of the consistency of Mexican/Mexican American preadolescents' lifetime substance use reports.

    PubMed

    Wagstaff, David A; Kulis, Stephen; Elek, Elvira

    2009-01-01

    In the Fall of 2004, 1,948 5th grade students from Phoenix, AZ enrolled in an evaluation of a school-based, substance use prevention intervention. To assess the consistency of Mexican and Mexican-American students' self-reports of lifetime substance use, the present study analyzed data reported by 1,418 students who reported Mexican ancestry and completed 2 to 6 questionnaires administered over a 40-month period. By wave 6, which was completed in March 2008, lifetime alcohol, cigarette, marijuana, and inhalant use rates were 86.0%, 65.0%, 64.5%, and 62.1%, respectively. Corresponding rescission rates were 24.0%, 9.6%, 5.8%, and 9.2%. Reporting patterns with one "Yes-No" sequence accounted for more than 88% of the inconsistent self-reports. This finding suggests that the majority of Mexican/Mexican-American preadolescents participating in a substance use prevention intervention provided logically consistent self-reports of lifetime substance use.

  18. Effects of lifetime ethanol consumption on postural control: a computerized dynamic posturography study.

    PubMed

    Ahmad, Saad; Rohrbaugh, John W; Anokhin, Andrey P; Sirevaag, Erik J; Goebel, Joel A

    2002-01-01

    The relationship between lifetime alcohol consumption and postural control was investigated in 35 subjects with no clinically-detectable neurologic abnormalities, using computerized dynamic posturography (CDP) procedures. The estimated total number of lifetime alcoholic drinks was positively correlated with anteroposterior sway spectral power within the 2-4 Hz and 4-6 Hz frequency bands, in three Sensory Organization Test (SOT) conditions: eyes closed with stable support surface (SOT 2), eyes open with sway-referenced support (SOT 4), and eyes closed with sway-referenced support (SOT 5). All correlations remained significant after controlling for subject age, and were increased after excluding nine drug-abusing subjects. In contrast to the strong findings for frequency-based measures, no correlation was observed using conventional amplitude-based sway measures. These results suggest that 1) alcohol consumption compromises postural control in an exposure-dependent manner, and 2) sway frequency analysis reveals pathological processes not manifested in conventional CDP measures of sway amplitude.

  19. Using fluorescence lifetime microscopy to study the subcellular localization of anthocyanins.

    PubMed

    Chanoca, Alexandra; Burkel, Brian; Kovinich, Nik; Grotewold, Erich; Eliceiri, Kevin W; Otegui, Marisa S

    2016-12-01

    Anthocyanins are flavonoid pigments that accumulate in most seed plants. They are synthesized in the cytoplasm but accumulate inside the vacuoles. Anthocyanins are pigmented at the lower vacuolar pH, but in the cytoplasm they can be visualized based on their fluorescence properties. Thus, anthocyanins provide an ideal system for the development of new methods to investigate cytoplasmic pools and association with other molecular components. We have analyzed the fluorescence decay of anthocyanins by fluorescence lifetime imaging microscopy (FLIM), in both in vitro and in vivo conditions, using wild-type and mutant Arabidopsis thaliana seedlings. Within plant cells, the amplitude-weighted mean fluorescence lifetime (τm ) correlated with distinct subcellular localizations of anthocyanins. The vacuolar pool of anthocyanins exhibited shorter τm than the cytoplasmic pool. Consistently, lowering the pH of anthocyanins in solution shortened their fluorescence decay. We propose that FLIM is a useful tool for understanding the trafficking of anthocyanins and, potentially, for estimating vacuolar pH inside intact plant cells.

  20. Studies of beam dynamics in relativistic klystron two-beam accelerators

    SciTech Connect

    Lidia, Steven M.

    1999-11-01

    Two-beam accelerators (TBAs) based upon free-electron lasers (FELs) or relativistic klystrons (RK-TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band (~8-12 GHz) through Ka band (~ 30-35 GHz) frequency regions. Provided that further prototyping shows stable beam propagation with minimal current loss and production of good quality, high-power rf fields, this technology is compatible with current schemes for electron-positron colliders in the multi-TeV center-of-mass scale. A new method of simulating the beam dynamics in accelerators of this type has been developed in this dissertation. There are three main components to this simulation. The first is a tracking algorithm to generate nonlinear transfer maps for pushing noninteracting particles through the external fields. The second component is a 3D Particle-In-Cell (PIC) algorithm that solves a set of Helmholtz equations for the self-fields, including the conducting boundary condition, and generates impulses that are interleaved with the nonlinear maps by means of a split-operation algorithm. The Helmholtz equations are solved by a multi-grid algorithm. The third component is an equivalent circuit equation solver that advances the modal rf cavity fields in time due to excitation by the modulated beam. The RTA project is described, and the simulation code is used to design the latter portions of the experiment. Detailed calculations of the beam dynamics and of the rf cavity output are presented and discussed. A beamline design is presented that will generate nearly 1.2 GW of power from 40 input, gain, and output rv cavities over a 10 m distance. The simulations show that beam current losses are acceptable, and that longitudinal and transverse focusing techniques are sufficient capable of maintaining a high degree of beam quality along the entire beamline. Additional experimental efforts are also

  1. Studies of beam dynamics in relativistic klystron two-beam accelerators

    SciTech Connect

    Lidia, Steven M.

    1999-11-01

    Two-beam accelerators (TBAs) based upon free-electron lasers (FELs) or relativistic klystrons (RK-TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band (~8-12 GHz) through Ka band (~ 30-35 GHz) frequency regions. Provided that further prototyping shows stable beam propagation with minimal current loss and production of good quality, high-power rf fields, this technology is compatible with current schemes for electron-positron colliders in the multi-TeV center-of-mass scale. A new method of simulating the beam dynamics in accelerators of this type has been developed in this dissertation. There are three main components to this simulation. The first is a tracking algorithm to generate nonlinear transfer maps for pushing noninteracting particles through the external fields. The second component is a 3D Particle-In-Cell (PIC) algorithm that solves a set of Helmholtz equations for the self-fields, including the conducting boundary condition, and generates impulses that are interleaved with the nonlinear maps by means of a split-operation algorithm. The Helmholtz equations are solved by a multi-grid algorithm. The third component is an equivalent circuit equation solver that advances the modal rf cavity fields in time due to excitation by the modulated beam. The RTA project is described, and the simulation code is used to design the latter portions of the experiment. Detailed calculations of the beam dynamics and of the rf cavity output are presented and discussed. A beamline design is presented that will generate nearly 1.2 GW of power from 40 input, gain, and output rv cavities over a 10 m distance. The simulations show that beam current losses are acceptable, and that longitudinal and transverse focusing techniques are sufficient capable of maintaining a high degree of beam quality along the entire beamline. Additional experimental efforts are also

  2. Cellular track model for study of heavy ion beams

    NASA Technical Reports Server (NTRS)

    Shinn, Judy L.; Katz, Robert; Cucinotta, Francis A.; Wilson, John W.; Ngo, Duc M.

    1993-01-01

    Track theory is combined with a realistic model of a heavy ion beam to study the effects of nuclear fragmentation on cell survival and biological effectiveness. The effects of secondary reaction products are studied as a function of depth in a water column. Good agreement is found with experimental results for the survival of human T-l cells exposed to monoenergetic carbon, neon, and argon beams under aerobic and hypoxia conditions. The present calculation, which includes the effect of target fragmentation, is a significant improvement over an earlier calculation because of the use of a vastly improved beam model with no change in the track theory or cellular response parameters.

  3. Polarization Studies in Fast-Ion Beam Spectroscopy

    SciTech Connect

    Trabert, E

    2001-12-20

    In a historical review, the observations and the insight gained from polarization studies of fast ions interacting with solid targets are presented. These began with J. Macek's recognition of zero-field quantum beats in beam-foil spectroscopy as indicating alignment, and D.G. Ellis' density operator analysis that suggested the observability of orientation when using tilted foils. Lastly H. Winter's studies of the ion-beam surface interaction at grazing incidence yielded the means to produce a high degree of nuclear orientation in ion beams.

  4. Study of propagation of vortex beams in aerosol optical medium.

    PubMed

    Porfirev, Alexey P; Kirilenko, Mikhail S; Khonina, Svetlana N; Skidanov, Roman V; Soifer, Victor A

    2017-04-10

    A theoretical and experimental study of the propagation of vortex laser beams in a random aerosol medium is presented. The theoretical study is based on the extended Huygens-Fresnel principle with the generation of a random field, using the fast Fourier transform. The simulation shows that the stability of vortex beams to fluctuations of an optical medium falls with rising order of optical vortices. Moreover, a coherence length (radius) of the random medium is of great importance. The coherence radius extension affects adversely the conservation of a beam structure in the random medium. During further free-space propagation, increasing coherence enables reduction of the negative effects of fluctuations for beams with high-value topological charges. Experimental studies in the random aerosol medium have shown that at small distances vortex beams mostly demonstrate lower stability than a Gaussian beam. However, at considerable distances, vortex beams start to demonstrate greater stability that may be explained by their capacity to be regenerated after they passed obstacles.

  5. Study of the bending vibration characteristic of phononic crystals beam-foundation structures by Timoshenko beam theory

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Ni, Zhi-Qiang; Jiang, Lin-Hua; Han, Lin; Kang, Xue-Wei

    2015-07-01

    Vibration problems wildly exist in beam-foundation structures. In this paper, finite periodic composites inspired by the concept of ideal phononic crystals (PCs), as well as Timoshenko beam theory (TBT), are proposed to the beam anchored on Winkler foundation. The bending vibration band structure of the PCs Timoshenko beam-foundation structure is derived from the modified transfer matrix method (MTMM) and Bloch's theorem. Then, the frequency response of the finite periodic composite Timoshenko beam-foundation structure by the finite element method (FEM) is performed to verify the above theoretical deduction. Study shows that the Timoshenko beam-foundation structure with periodic composites has wider attenuation zones compared with homogeneous ones. It is concluded that TBT is more available than Euler beam theory (EBT) in the study of the bending vibration characteristic of PCs beam-foundation structures with different length-to-height ratios.

  6. Molecular beam studies of reaction dynamics

    SciTech Connect

    Lee, Y.T.

    1987-03-01

    Purpose of this research project is two-fold: (1) to elucidate detailed dynamics of simple elementary reactions which are theoretically important and to unravel the mechanism of complex chemical reactions or photo chemical processes which play an important role in many macroscopic processes and (2) to determine the energetics of polyatomic free radicals using microscopic experimental methods. Most of the information is derived from measurement of the product fragment translational energy and angular distributions using unique molecular beam apparati designed for these purposes.

  7. Low-spin lifetime measurements in {sup 74}Kr

    SciTech Connect

    Valiente-Dobon, J. J.; Svensson, C. E.; Grinyer, G. F.; Hyland, B.; Phillips, A. A.; Schumaker, M. A.; Afanasjev, A. V.; Ragnarsson, I.; Andreoiu, C.; Appelbe, D. E.; Austin, R. A. E.; Cameron, J. A.; Waddington, J. C.; Ball, G. C.; Hodgson, D. F.; Smith, M. B.; Carpenter, M. P.; Moore, F.; Mukherjee, G.; Seweryniak, D.

    2008-02-15

    The nucleus {sup 74}Kr has been populated in the {sup 40}Ca({sup 40}Ca,2p{alpha}){sup 74}Kr fusion-evaporation reaction at a beam energy of 165 MeV and studied using the Gammasphere and Microball multidetector arrays. The lifetimes for low-spin states in the ground-state and two signature-split negative-parity bands were determined using the Doppler-shift attenuation method. These results are discussed together with the lifetimes measured for the high-spin states of these bands and compared with theoretical calculations.

  8. Low-spin lifetime measurements in Kr74

    NASA Astrophysics Data System (ADS)

    Valiente-Dobón, J. J.; Svensson, C. E.; Afanasjev, A. V.; Ragnarsson, I.; Andreoiu, C.; Appelbe, D. E.; Austin, R. A. E.; Ball, G. C.; Cameron, J. A.; Carpenter, M. P.; Clark, R. M.; Cromaz, M.; Dashdorj, D.; Fallon, P.; Freeman, S. J.; Garrett, P. E.; Görgen, A.; Grinyer, G. F.; Hodgson, D. F.; Hyland, B.; Jenkins, D.; Johnston-Theasby, F.; Joshi, P.; Kelsall, N. S.; Macchiavelli, A. O.; Mengoni, D.; Moore, F.; Mukherjee, G.; Phillips, A. A.; Reviol, W.; Sarantites, D.; Schumaker, M. A.; Seweryniak, D.; Smith, M. B.; Waddington, J. C.; Wadsworth, R.; Ward, D.

    2008-02-01

    The nucleus Kr74 has been populated in the Ca40(Ca40,2pα)Kr74 fusion-evaporation reaction at a beam energy of 165 MeV and studied using the Gammasphere and Microball multidetector arrays. The lifetimes for low-spin states in the ground-state and two signature-split negative-parity bands were determined using the Doppler-shift attenuation method. These results are discussed together with the lifetimes measured for the high-spin states of these bands and compared with theoretical calculations.

  9. Spes: Exotic Beams for Nuclear Physics Studies

    NASA Astrophysics Data System (ADS)

    Andrighetto, Alberto; Manzolaro, Mattia; Corradetti, Stefano; Scarpa, Daniele; Vasquez, Jesu; Rossignoli, Massimo; Monetti, Alberto; Calderolla, Michele; Prete, Gianfranco

    2014-02-01

    The SPES project at Laboratori di Legnaro of INFN (Italy) is concentrating on the production of neutron-rich radioactive nuclei for nuclear physics experiments using uranium fission at a rate of 1013 fission/s. The emphasis on neutron-rich isotopes is justified by the fact that this vast territory has been little explored. The Radioactive Ion Beam (RIB) will be produced by the ISOL technique using proton induced fission on a direct target of UCx. The most critical element of the SPES project is the Multi-Foil Direct Target. Up to the present time, the proposed target represents an innovation in terms of its capability to sustain the primary beam power. This talk will present the status of the project financed by INFN, which is actually in the construction phase at Legnaro. In particular, developments related to the target and the ion-source activities using the surface ion source, plasma ion source, and laser ion source techniques will be reported.

  10. Study of behavior and determination of customer lifetime value(CLV) using Markov chain model

    NASA Astrophysics Data System (ADS)

    Permana, Dony; Indratno, Sapto Wahyu; Pasaribu, Udjianna S.

    2014-03-01

    Customer Lifetime Value or CLV is a restriction on interactive marketing to help a company in arranging financial for the marketing of new customer acquisition and customer retention. Additionally CLV can be able to segment customers for financial arrangements. Stochastic models for the fairly new CLV used a Markov chain. In this model customer retention probability and new customer acquisition probability play an important role. This model is originally introduced by Pfeifer and Carraway in 2000 [1]. They introduced several CLV models, one of them only involves customer and former customer. In this paper we expand the model by adding the assumption of the transition from former customer to customer. In the proposed model, the CLV value is higher than the CLV value obtained by Pfeifer and Caraway model. But our model still requires a longer convergence time.

  11. Study of behavior and determination of customer lifetime value(CLV) using Markov chain model

    SciTech Connect

    Permana, Dony; Indratno, Sapto Wahyu; Pasaribu, Udjianna S.

    2014-03-24

    Customer Lifetime Value or CLV is a restriction on interactive marketing to help a company in arranging financial for the marketing of new customer acquisition and customer retention. Additionally CLV can be able to segment customers for financial arrangements. Stochastic models for the fairly new CLV used a Markov chain. In this model customer retention probability and new customer acquisition probability play an important role. This model is originally introduced by Pfeifer and Carraway in 2000 [1]. They introduced several CLV models, one of them only involves customer and former customer. In this paper we expand the model by adding the assumption of the transition from former customer to customer. In the proposed model, the CLV value is higher than the CLV value obtained by Pfeifer and Caraway model. But our model still requires a longer convergence time.

  12. A comparative study of the stress-rupture lifetimes of high-strength carbon fibers

    NASA Astrophysics Data System (ADS)

    Grimes-Ledesma, Lorie

    Stress-rupture life is the time a composite can survive under load at an assigned risk level. The stress-rupture lifetimes of high-strength PAN-based carbon fibers are important to the development and use of lightweight composite structures such as composite overwrapped pressure vessels (COPVs). To quantify appropriate stress-rupture risk levels based on available models, quantification of single fiber variability and lifetime is necessary to understand the variability observed in larger composite structures. In the present work, three PAN-based carbon fibers commonly used in COPV technology were examined, Hexcel IM9, Toray T700, and Toray T1000. The diameter of each fiber type was quantified by measuring samples in the scanning electron microscope and failure loads were determined by performing tensile tests on single fibers. Weibull statistics were used to describe the results. Fractography was performed on IM9 and T1000 fibers after tensile failure. The fracture surfaces are consistent with crack growth from a volume or surface defect. Stress-rupture testing was completed at two stress levels at each fiber type, 97% and 93% of the mean fiber strength for each of the fiber types. The results indicate that differences in stress-rupture life performance exist between the three fiber types. Differences in stress ratio of between 5 and 10% were observed, which may translate to significant difference in stress-rupture life behavior for larger composite structures. The results indicate that a relationship may exist between strength and stress-rupture life. However, if this relationship exists, it is not a simple one, and the relationship is likely complicated by manufacturing.

  13. An analytical study on the bending of prismatic SMA beams

    NASA Astrophysics Data System (ADS)

    Ostadrahimi, Alireza; Arghavani, Jamal; Poorasadion, Saeid

    2015-12-01

    In this study, an analytical solution is presented for pure bending of shape memory alloy (SMA) beams with symmetric cross section as well as symmetric behavior in tension and compression. To this end, a three-dimensional constitutive equation is reduced to one-dimensional form and employed to study the bending response of SMA beams at high (pseudo-elasticity) and low (shape memory effect) temperatures. An analytical expression for bending stress as well as polynomial approximation for shear stress and deflection are obtained. Derived equations for bending are employed to analyze an SMA beam with rectangular cross section and results are compared with those of the finite element method. The results of this work show good agreement when compared with experimental data and finite element results. Furthermore, the existence of several zero-stress fibers during unloading of SMA beams at low temperature is demonstrated.

  14. Ionosphere/microwave beam interaction study

    NASA Technical Reports Server (NTRS)

    Gordon, W. E.; Duncan, L. M.

    1978-01-01

    The microwave beam of the Solar Power Satellite (SPS) is predicted to interact with the ionosphere producing thermal runaway up to an altitude of about 100 kilometers at a power density threshold of 12 mW/cm sq (within a factor of two). The operation of the SPS at two frequencies, 2450 and 5800 MHz, is compared. The ionosphere interaction is less at the higher frequency, but the tropospheric problem scattering from heavy rain and hail is worse at the higher frequency. Microwave signals from communication satellites were observed to scintillate, but there is some concern that the uplink pilot signal may be distorted by the SPS heated ionosphere. The microwave scintillations are only observed in the tropics in the early evenings near the equinoxes. Results indicate that large phase errors in the uplink pilot signal can be reduced.

  15. Positron beam studies of transients in semiconductors

    NASA Astrophysics Data System (ADS)

    Beling, C. D.; Ling, C. C.; Cheung, C. K.; Naik, P. S.; Zhang, J. D.; Fung, S.

    2006-02-01

    Vacancy-sensing positron deep level transient spectroscopy (PDLTS) is a positron beam-based technique that seeks to provide information on the electronic ionization levels of vacancy defects probed by the positron through the monitoring of thermal transients. The experimental discoveries leading to the concept of vacancy-sensing PDLTS are first reviewed. The major problem associated with this technique is discussed, namely the strong electric fields establish in the near surface region of the sample during the thermal transient which tend to sweep positrons into the contact with negligible defect trapping. New simulations are presented which suggest that under certain conditions a sufficient fraction of positrons may be trapped into ionizing defects rendering PDLTS technique workable. Some suggestions are made for techniques that might avoid the problematic electric field problem, such as optical-PDLTS where deep levels are populated using light and the use of high forward bias currents for trap filling.

  16. Lifetime Smoking History and Cause-Specific Mortality in a Cohort Study with 43 Years of Follow-Up

    PubMed Central

    Taghizadeh, Niloofar; Vonk, Judith M.; Boezen, H. Marike

    2016-01-01

    Background In general, smoking increases the risk of mortality. However, it is less clear how the relative risk varies by cause of death. The exact impact of changes in smoking habits throughout life on different mortality risks is less studied. Methods We studied the impact of baseline and lifetime smoking habits, and duration of smoking on the risk of all-cause mortality, mortality of cardiovascular diseases (CVD), chronic obstructive pulmonary disease (COPD), any cancer and of the four most common types of cancer (lung, colorectal, prostate, and breast cancer) in a cohort study (Vlagtwedde-Vlaardingen 1965–1990, with a follow-up on mortality status until 2009, n = 8,645). We used Cox regression models adjusted for age, BMI, sex, and place of residence. Since previous studies suggested a potential effect modification of sex, we additionally stratified by sex and tested for interactions. In addition, to determine which cause of death carried the highest risk we performed competing-risk analyses on mortality due to CVD, cancer, COPD and other causes. Results Current smoking (light, moderate, and heavy cigarette smoking) and lifetime persistent smoking were associated with an increased risk of all-cause, CVD, COPD, any cancer, and lung cancer mortality. Higher numbers of pack years at baseline were associated with an increased risk of all-cause, CVD, COPD, any cancer, lung, colorectal, and prostate cancer mortality. Males who were lifetime persistent pipe/cigar smokers had a higher risk of lung cancer [HR (95% CI) = 7.72 (1.72–34.75)] as well as all-cause and any cancer mortality. A longer duration of smoking was associated with a higher risk of COPD, any and lung cancer [HR (95% CI) = 1.06 (1.00–1.12), 1.03 (1.00–1.06) and 1.10 (1.03–1.17) respectively], but not with other mortality causes. The competing risk analyses showed that ex- and current smokers had a higher risk of cancer, CVD, and COPD mortality compared to all other mortality causes. In

  17. Topics on distance correlation, feature screening and lifetime expectancy with application to Beaver Dam eye study data

    NASA Astrophysics Data System (ADS)

    Kong, Jing

    This thesis includes 4 pieces of work. In Chapter 1, we present the work with a method for examining mortality as it is seen to run in families, and lifestyle factors that are also seen to run in families, in a subpopulation of the Beaver Dam Eye Study that has died by 2011. We find significant distance correlations between death ages, lifestyle factors, and family relationships. Considering only sib pairs compared to unrelated persons, distance correlation between siblings and mortality is, not surprisingly, stronger than that between more distantly related family members and mortality. Chapter 2 introduces a feature screening procedure with the use of distance correlation and covariance. We demonstrate a property for distance covariance, which is incorporated in a novel feature screening procedure based on distance correlation as a stopping criterion. The approach is further implemented to two real examples, namely the famous small round blue cell tumors data and the Cancer Genome Atlas ovarian cancer data Chapter 3 pays attention to the right censored human longevity data and the estimation of lifetime expectancy. We propose a general framework of backward multiple imputation for estimating the conditional lifetime expectancy function and the variance of the estimator in the right censoring setting and prove the properties of the estimator. In addition, we apply the method to the Beaver Dam eye study data to study human longevity, where the expected human lifetime are modeled with smoothing spline ANOVA based on the covariates including baseline age, gender, lifestyle factors and disease variables. Chapter 4 compares two imputation methods for right censored data, namely the famous Buckley-James estimator and the backward imputation method proposed in Chapter 3 and shows that backward imputation method is less biased and more robust with heterogeneity.

  18. Lifetime measurements in 180Pt

    NASA Astrophysics Data System (ADS)

    Chen, Q. M.; Wu, X. G.; Chen, Y. S.; Li, C. B.; Gao, Z. C.; Li, G. S.; Chen, F. Q.; He, C. Y.; Zheng, Y.; Hu, S. P.; Zhong, J.; Wu, Y. H.; Li, H. W.; Luo, P. W.

    2016-04-01

    Lifetimes of the yrast states in 180Pt have been measured from 4+ to 8+ using the recoil distance Doppler-shift technique in the coincidence mode. These states were populated by the reaction 156Gd(28Si,4 n )180Pt at a beam energy of 144 MeV. The differential decay curve method was applied to determine the lifetimes from experimental coincidence data. The B (E 2 ) values extracted from lifetimes increase with increasing spin, implying rotor behavior, but do not show the typical shape coexistence where the B (E 2 ) values present a rapid increase at very low spins. Calculations based on the triaxial projected shell model were performed for the yrast states in 180Pt and the results of both energies and E 2 transition probabilities reproduce the experimental data very well. The result also shows that a better description of the yrast band in 180Pt requires consideration of the γ degree of freedom.

  19. Study of the beam profile and position instability of a post-accelerated pseudospark-sourced electron beam

    NASA Astrophysics Data System (ADS)

    Zhao, J.; Yin, H.; Zhang, L.; Shu, G.; He, W.; Phelps, A. D. R.; Cross, A. W.; Pang, L.; Zhang, Q.

    2017-03-01

    A pseudospark-sourced electron beam is a promising candidate for driving a THz millimeter wave radiation source. However, the physics governing the electron beam density profile and the beam center deviation from the axis of the structure, which may be caused by the randomness in the pseudospark discharge process, remains still unclear especially for the high energy component of the pseudospark-sourced electron beam, which is usually non-mono-energetic. It is essential to study the electron beam density profile and the beam center position distribution for optimizing the pseudospark discharge configuration. In this paper, images of some single-shot electron beam pulses have been captured using a 50 μm thickness stopping copper foil and a phosphor screen coated with a P47 scintillator to study the electron beam density profile and the beam center position distribution of the high energy component of the electron beam. The experiments have been carried out on two pseudospark discharge configurations with two different size hollow cathode cavities. The influence of the cathode aperture of each configuration has also been studied according to the beam images. Experimental results show that the beam profile of the high energy component has a Lorentzian distribution and is much smaller than the axial aperture size with the beam centers dispersing within a certain range around the axis of the discharge structure. The pseudospark-sourced electron beam with a larger hollow cathode cavity shows a smaller full width at half maximum radius and a more concentrated beam center distribution.

  20. Optics Studies of the LHC Beam Transfer Line TI8

    SciTech Connect

    J. Wenninger; G. Arduini; B. Goddard; D. Jacquet; V. Kain; M. Lamont; V. Mertens; J.A. Uythoven; Y.-C. Chao

    2005-05-16

    The optics of the newly commissioned LHC beam transfer line TI 8 was studied with beam trajectories, dispersion and profile measurements. Steering magnet response measurements were used to analyze the quality of the steering magnets and of the beam position monitors. A simultaneous fit of the quadrupole strengths was used to search for setting or calibration errors. Residual coupling between the planes was evaluated using high statistics samples of trajectories. Initial conditions for the optics at the entrance of the transfer line were reconstructed from beam profile measurements with Optical Transition Radiation monitors. The paper presents the various analysis methods and their errors. The expected emittance growth arising from optical mismatch into the LHC is evaluated.

  1. Lifetime productivity losses associated with obesity status in early adulthood: a population-based study of Swedish men.

    PubMed

    Neovius, Kristian; Rehnberg, Clas; Rasmussen, Finn; Neovius, Martin

    2012-09-01

    Obesity is a well-known risk factor for sick leave, disability pension and premature death. Obesity is therefore presumably related to increased productivity losses. The aim of this study was to estimate the lifetime productivity losses to society associated with obesity status. This study was based on a 38-year follow-up of a nationwide cohort of 45 920 Swedish men performing mandatory military conscription tests at age 18.7 ± 0.5 years. Body mass index (BMI) based on measured height and weight at the time of military conscription tests was used to define underweight (<18.5 kg/m(2)), normal weight (18.5-24.9 kg/m(2)), overweight (25.0-29.9 kg/m(2)) and obesity (≥30.0 kg/m(2)). Data on sick leave, disability pension and premature death were retrieved from national registers. The calculations were adjusted for socioeconomic index, smoking and muscular strength. Using the human capital approach, the lifetime productivity losses were calculated as 55.6 (95% CI 50.7, 62.0) × €1000 and 55.6 (95% CI 50.9, 61.4) × €1000 for underweight and normal weight, respectively, and 72.6 (95% CI 66.3, 80.7) × €1000 and 95.4 (95% CI 89.0, 102.9) × €1000 for overweight and obesity, respectively. If using the friction cost method instead, the estimated productivity losses were reduced by about 80%. Obesity is associated with almost twice as high productivity losses to society as for normal weight over a lifetime. These costs are important to include in health economic analyses of obesity intervention programmes in order to ensure an effective allocation of resources from a societal perspective.

  2. A surface energy spectral study on the bone heterogeneity and beam obliquity using the flattened and unflattened photon beams.

    PubMed

    Chow, James C L; Owrangi, Amir M

    2016-01-01

    Using flattened and unflattened photon beams, this study investigated the spectral variations of surface photon energy and energy fluence in the bone heterogeneity and beam obliquity. Surface dose enhancement is a dosimetric concern when using unflattened photon beam in radiotherapy. It is because the unflattened photon beam contains more low-energy photons which are removed by the flattening filter of the flattened photon beam. We used a water and bone heterogeneity phantom to study the distributions of energy, energy fluence and mean energy of the 6 MV flattened and unflattened photon beams (field size = 10 cm × 10 cm) produced by a Varian TrueBEAM linear accelerator. These elements were calculated at the phantom surfaces using Monte Carlo simulations. The photon energy and energy fluence calculations were repeated with the beam angle turned from 0° to 15°, 30° and 45° in the water and bone phantom. Spectral results at the phantom surfaces showed that the unflattened photon beams contained more photons concentrated mainly in the low-energy range (0-2 MeV) than the flattened beams associated with a flattening filter. With a bone layer of 1 cm under the phantom surface and within the build-up region of the 6 MV photon beam, it is found that both the flattened and unflattened beams had slightly less photons in the energy range <0.4 MeV compared to the water phantom. This shows that the presence of the bone decreased the low-energy photon backscatters to the phantom surface. When both the flattened and unflattened photon beams were rotated from 0° to 45°, the number of photon and mean photon energy increased. This indicates that both photon beams became more hardened or penetrate when the beam angle increased. In the presence of bone, the mean energies of both photon beams increased. This is due to the absorption of low-energy photons by the bone, resulting in more beam hardening. This study explores the spectral relationships of surface photon

  3. A surface energy spectral study on the bone heterogeneity and beam obliquity using the flattened and unflattened photon beams

    PubMed Central

    Chow, James C.L.; Owrangi, Amir M.

    2016-01-01

    Aim Using flattened and unflattened photon beams, this study investigated the spectral variations of surface photon energy and energy fluence in the bone heterogeneity and beam obliquity. Background Surface dose enhancement is a dosimetric concern when using unflattened photon beam in radiotherapy. It is because the unflattened photon beam contains more low-energy photons which are removed by the flattening filter of the flattened photon beam. Materials and methods We used a water and bone heterogeneity phantom to study the distributions of energy, energy fluence and mean energy of the 6 MV flattened and unflattened photon beams (field size = 10 cm × 10 cm) produced by a Varian TrueBEAM linear accelerator. These elements were calculated at the phantom surfaces using Monte Carlo simulations. The photon energy and energy fluence calculations were repeated with the beam angle turned from 0° to 15°, 30° and 45° in the water and bone phantom. Results Spectral results at the phantom surfaces showed that the unflattened photon beams contained more photons concentrated mainly in the low-energy range (0–2 MeV) than the flattened beams associated with a flattening filter. With a bone layer of 1 cm under the phantom surface and within the build-up region of the 6 MV photon beam, it is found that both the flattened and unflattened beams had slightly less photons in the energy range <0.4 MeV compared to the water phantom. This shows that the presence of the bone decreased the low-energy photon backscatters to the phantom surface. When both the flattened and unflattened photon beams were rotated from 0° to 45°, the number of photon and mean photon energy increased. This indicates that both photon beams became more hardened or penetrate when the beam angle increased. In the presence of bone, the mean energies of both photon beams increased. This is due to the absorption of low-energy photons by the bone, resulting in more beam hardening. Conclusions This study

  4. Non Linear Beam Dynamics at DAPHINE

    SciTech Connect

    Raimondi, Pantaleo

    2002-08-21

    Studies and measurements have been performed at DAPHINE to improve dynamic aperture, beam lifetime and beam-beam performance. Measured tune scans for different working points are presented. After the measurement of an octupole-like term in the wiggler field, decoherence measurements with wigglers on and off have been performed. The effect of this cubic term on the chromaticity and dynamic aperture is presented.

  5. Summary update of the Brookhaven tritium toxicity program with emphasis on recent cytogenetic and lifetime-shortening studies

    SciTech Connect

    Carsten, A.L.; Benz, R.D.; Hughes, W.P.; Ichimasa, Yusuke; Ikushima, Takaji; Tezuka, Hideo

    1988-01-01

    A number of years ago a multiparameter program to evaluate the toxicity of tritiated water (HTO) was undertaken in the Medical Department at Brookhaven National Laboratory. The results of most of these studies have been published and will receive brief attention. Emphasis will be placed on the unpublished studies involving the induction of sister chromatid exchanges (SCE's) in bone marrow of mice, new biochemical information, and preliminary results on lifetime-shortening and carcinogenesis. In brief, male Hale-Stoner Brookhaven (HSB) mice maintained on HTO concentrations ranging from 3.0 to 30.0 ..mu..Ci/ml exhibited essentially the same number of SCE's per cell throughout their lifetime. Control mice showed a decrease in number of SCE's with age. The lack of a dose-response effect and the constant level of SCE's in HTO mice as compared to controls will be discussed. In the carcinogenesis study C57BL/6J male mice received various x-ray or HTO regimens. Mortality data from these and other studies in which CBA/Ca/BNL mice received single x-ray exposures or equivalent integrated dose exposures by single HTO injections will be discussed. 25 refs., 4 figs.

  6. Residual on column host cell protein analysis during lifetime studies of protein A chromatography.

    PubMed

    Lintern, Katherine; Pathak, Mili; Smales, C Mark; Howland, Kevin; Rathore, Anurag; Bracewell, Daniel G

    2016-08-26

    Capacity reduction in protein A affinity chromatography with extended cycling during therapeutic antibody manufacture is well documented. Identification of which residual proteins remain from previous cycles during the lifetime of these adsorbent materials is required to understand their role in this ageing process, but represents a significant metrological challenge. Scanning electron microscopy (SEM) and liquid chromatography mass spectrometry (LC-MS/MS) are combined to detect and map this phenomenon of protein carry-over. We show that there is a morphological change at the surface of the agarose resin, revealing deposits on the polymer fibres increasing with cycle number. The amount of residual host cell proteins (HCPs) by LC-MS/MS present on the resin is shown to increase 10-fold between 50 and 100 cycles. During this same period the functional class of the predominant HCPs associated with the resin increased in diversity, with number of proteins identified increasing 5-fold. This ageing is observed in the context of the product quality of the eluate HCP and protein A leachate concentration remaining constant with cycle number.

  7. Ion source studies for particle beam accelerators

    SciTech Connect

    Bieg, K.W.; Burns, E.J.T.; Olsen, J.N.; Dorrell, L.R.

    1985-05-01

    High power particle beam accelerators are being developed for use in inertial confinement fusion applications. These pulsed power accelerators require sources of low atomic number ions (e.g., protons, deuterons, carbon, or lithium). The sources must be of high purity for efficient accelerator operation and proper target coupling, must have a rapid ''turn-on,'' and must be compatible with ion diode configurations under development. A particular type of source presently being investigated is the flashover ion source which generates ions by means of the vacuum flashover of an insulating anode material when the high voltage pulse arrives at the diode. We have developed an applied-magnetic-field, extraction ion diode for the 0.03 TW Nereus accelerator specifically to investigate these sources. Extracted ion species are measured by means of a Thomson-parabola ion analyzer, dB/dt current monitors, and Faraday cups. Experiments have been performed to investigate the surface flashover mechanism and the effects of various dielectric source materials, anode preparation methods (including rf glow discharge cleaning), and vacuum conditions on ion species and diode operation.

  8. Study of crack patterns in beam column joint due to upwards anchoring beam effect

    NASA Astrophysics Data System (ADS)

    Sabariman, Bambang; Sofianto, Mochamad Firmansyah

    2017-06-01

    Beam-column joint (BCJ) of reinforced concrete is an area of critical which must be carefully designed to absorb the seismic energy. Inability to absorb seismic energy will cause serious damage to structural failure. It will lead to shear failure, i.e. brittle and endanger users of the building if the BCJ area is not designed properly. In order to get a building structure is safe and resistant to disasters, mainly due to the earthquake, the structure must be designed in accordance to the rules of standard construction (eligible detailing). In general, the anchorages (detailing) reinforcement beams to the column is pointing downwards, however, what if the steel anchoring beams are pointing upwards. Different anchoring will result in the behavior of different structures, such as fracturing pattern. This study observes two anchoring model, by making two test specimens of BCJ. One set of reinforcement beams anchored BCJ upward and downward respectively, which are applied with monotonic static load. The study investigated the pattern of cracks and ductility of the beam displacement on BCJ. The results showed that the downward anchoring in the fracturing pattern out of the area BCJ was anchoring upward pattern rift goes deep into the area BCJ, thus anchoring above makes BCJ unsafe. Downward anchoring are more ductile than the upward anchoring, however the deflection of all BJC specimens was higher than the boundaries maximum deflection prediction (Δprediction = 10.45 mm < eksp Δexp-min = 13.15 mm), which can be assumed that all BCJ specimens were ductile, but it still in ductile limited due to displacement ductility μΔ<3,5.

  9. Lifetime exposure to traumatic psychological stress is associated with elevated inflammation in the heart and soul study

    PubMed Central

    O’Donovan, Aoife; Neylan, Thomas C.; Metzler, Thomas; Cohen, Beth E.

    2012-01-01

    Exposure to traumatic psychological stress increases risk for disease events and mortality in patients with cardiovascular disease (CVD). While the biological mechanisms of these effects are not known, inflammation may play a key role as it is both elevated by psychological stress and involved in the development and progression of CVD. In a prospective study of patients with stable CVD (n = 979), we examined if higher lifetime trauma exposure was associated with elevated levels of inflammation at baseline and at five-year follow-up, and with greater increases in inflammation over time. Inflammation was indexed by a composite score incorporating the inflammatory markers interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), C-reactive protein (CRP) and resistin. In follow-up analyses, we adjusted for sociodemographic factors, psychiatric disorders and health behaviors that were significantly associated with trauma exposure. Higher trauma exposure was associated with elevated inflammation at baseline (β = .09, p = .01) and at five-year follow-up (β = .09, p = .03). While levels of inflammation increased from baseline to follow-up in the sample, there was no significant association between trauma exposure and rate of change in inflammation. Findings were robust to adjustments for sociodemographic factors and psychiatric disorders, but health behaviors appeared to contribute to the association between trauma and inflammation at follow-up. This is the first large-scale demonstration of an association between lifetime trauma exposure and inflammation. High lifetime exposure to traumatic stress may contribute to an accelerated rate of CVD progression through elevated inflammation. PMID:22366689

  10. Experimental Study on Voided Reinforced Concrete Beams with Polythene Balls

    NASA Astrophysics Data System (ADS)

    Sivaneshan, P.; Harishankar, S.

    2017-07-01

    The primary component in any structure is concrete, that exist in buildings and bridges. In present situation, a serious problems faced by construction industry is exhaustive use of raw materials. Recent times, various methods are being adopted to limit the use of concrete. In structural elements like beams, polythene balls can be induced to reduce the usage of concrete. A simply supported reinforced concrete beam has two zones, one above neutral axis and other below neutral axis. The region below neutral axis is in tension and above neutral axis is in compression. As concrete is weak in tension, steel reinforcements are provided in tension zone. The concrete below the neutral axis acts as a stress transfer medium between the compression zone and tension zone. The concrete above the neutral axis takes minimum stress so that we could partially replace the concrete above neutral axis by creating air voids using recycled polythene balls. Polythene balls of varying diameters of 75 mm, 65 mm and 35 mm were partially replaced in compression zone. Hence the usage of concrete in beams and self-weight of the beams got reduced considerably. The Load carrying capacity, Deflection of beams and crack patterns were studied and compared with conventional reinforced concrete beams.

  11. Nuclear photofission studies with monochromatic γ ray beams

    NASA Astrophysics Data System (ADS)

    Csige, L.; Gulyás, J.; Habs, D.; Krasznahorkay, A.; Thirolf, P. G.; Tornyi, T. G.

    2012-07-01

    Two new research facilities will be ready for operation very soon (MEGa-Ray at Liver-more National Laboratory) or start construction (ELI-Nuclear Physics in Bucharest), both providing highly brilliant γ beams with so far unprecedented properties via Compton backscattering of laser photons from a high-quality, relativistic electron beam. With these intense, monochromatic γ beams, a new era of photonuclear physics will be enabled. A new research campaign is proposed to exploit the unprecedented properties of these highly-brilliant, novel γ beams on highly-selective studies of extremely deformed nuclei in the multiple-humped potential energy landscape of the actinides via photofission. With the unique γ beam bandwidth of ΔE/E = 10-3, we can aim at resolving individual resonances which could never be achieved so far due to the limited γ bandwidth of bremsstrahlung beams. Exploratory, non-bremsstrahlung photofission experiments are going to be performed very soon at the HIγS facility (Duke University, USA) to investigate the fine structure of the sub-barrier transmission resonances of the actinides.

  12. Nuclear photofission studies with monochromatic {gamma} ray beams

    SciTech Connect

    Csige, L.; Gulyas, J.; Habs, D.; Krasznahorkay, A.; Thirolf, P. G.; Tornyi, T. G.

    2012-07-09

    Two new research facilities will be ready for operation very soon (MEGa-Ray at Liver-more National Laboratory) or start construction (ELI-Nuclear Physics in Bucharest), both providing highly brilliant {gamma} beams with so far unprecedented properties via Compton backscattering of laser photons from a high-quality, relativistic electron beam. With these intense, monochromatic {gamma} beams, a new era of photonuclear physics will be enabled. A new research campaign is proposed to exploit the unprecedented properties of these highly-brilliant, novel {gamma} beams on highly-selective studies of extremely deformed nuclei in the multiple-humped potential energy landscape of the actinides via photofission. With the unique {gamma} beam bandwidth of {Delta}E/E = 10{sup -3}, we can aim at resolving individual resonances which could never be achieved so far due to the limited {gamma} bandwidth of bremsstrahlung beams. Exploratory, non-bremsstrahlung photofission experiments are going to be performed very soon at the HI{gamma}S facility (Duke University, USA) to investigate the fine structure of the sub-barrier transmission resonances of the actinides.

  13. The Fraction of the Sun's Lifetime in a Grand Minimum State Estimated from Studies of Solar-Type Stars

    NASA Astrophysics Data System (ADS)

    Lubin, D.

    2011-12-01

    The Maunder Minimum is a key event in climate change research, (1) from the vantage point as a natural control experiment in which greenhouse gas (GHG) abundances were at a pre-industrial constant while solar forcing changed by a magnitude comparable to recent GHG increases, and (2) given recent interest and speculation that a similar grand minimum might occur later this century. To date, periodicity in solar grand minima has been difficult to detect in geophysical proxy data, and an alternative approach involves estimating the frequency of the Sun's lifetime spent in a grand minimum state by searching for evidence of grand minima in solar-type stars. Most often this is done by measuring Ca H and K flux as an indicator of chromospheric activity, or by photometric observations of solar cycles on decadal timescales. Early estimates of grand minimum frequency in solar type stars ranged from 10-30%. However, these early studies inadvertently included many stars that have evolved off the main sequence. This paper discusses how measurements of stellar Lithium abundance, and spectroscopically constrained metallicity, are used as additional constraints on age and main sequence membership, to refine detections of grand minima in solar-type stars. Based on the most recent studies, an estimate emerges of 5-6% for the fraction of the Sun's lifetime spent in a low-activity and reduced luminosity state analogous to the Maunder Minimum.

  14. Adult attention-deficit/hyperactivity disorder: Associations between subtype and lifetime substance use – a clinical study

    PubMed Central

    Liebrenz, Michael; Gamma, Alex; Ivanov, Iliyan; Buadze, Anna; Eich, Dominique

    2016-01-01

    ADHD is the one of the most prevalent childhood disorders and has been associated with impairments persisting into adulthood. Specifically, childhood ADHD is an independent clinical risk factor for the development of later substance use disorders (SUD). Moreover, adults who meet diagnostic criteria for ADHD have shown high rates of comorbid SUDs. Few studies, however, have reported on the relationship between ADHD subtypes and SUD in adult samples. The purpose of this study was to characterize a clinical sample of adults with ADHD and to identify possible associations between ADHD subtypes, lifetime substance use, and if ADHD subtypes may be preferentially associated with specific substances of abuse. We recruited 413 adult ADHD patients, performed an evaluation of their ADHD and conducted an interview on their use of psychotropic substances. Complete data was obtained for 349 patients. Lifetime substance abuse or dependence was 26% and occasional use was 57% in this sample. The inattentive subtype was significantly less likely to abuse or be dependent on cocaine than the combined subtype. Our findings underscore the high rate of comorbidity between substance use and ADHD in adults. The more frequent abuse/dependence of cocaine by adult patients with hyperactive-impulsive symptoms should be kept in mind when treating this patient group. PMID:27853503

  15. Study of the beam-beam limit in e{sup +}e{sup -} circular colliders

    SciTech Connect

    Ohmi, K.; Tawada, M.; Cai, Y.; Kamada, S.; Oide, K.; Qiang, J.

    2004-04-02

    Beam-beam effects limit the luminosity of circular colliders. Once the bunch population exceeds a threshold, the luminosity increases at a slower rate. This phenomenon is called the beam-beam limit. Onset of the beam-beam limit has been analyzed with various simulation methods based on the weak-strong and strong-strong models. We have observed that an incoherent phenomenon is mainly concerned in the beam-beam limit. The simulation have shown that equilibrium distributions of the two colliding beams are distorted from Gaussians when the luminosity is limited. The beam-beam limit is estimated to be (xi) {approx} 0.1 for a B factory with damping time of several thousand turns.

  16. Beam dynamics and error study of the medium energy beam transport line in the Korea Heavy-Ion Medical Accelerator

    NASA Astrophysics Data System (ADS)

    Kim, Chanmi; Kim, Eun-San; Hahn, Garam

    2016-11-01

    The Korea Heavy Ion Medical Accelerator consists of an injector and a synchrotron for an ion medical accelerator that is the first carbon-ion therapy system in Korea. The medium energy beam transport(MEBT) line connects the interdigital H-mode drift tube linac and the synchrotron. We investigated the beam conditions after the charge stripper by using the LISE++ and the SRIM codes. The beam was stripped from C4+ into C6+ by using the charge stripper. We investigated the performance of a de-buncher in optimizing the energy spread and the beam distribution in z-dW/W (direction of beam progress-beam and energy) phase. We obtained the results of the tracking simulation and the error analysis by using the TRACK code. Possible misalignments and rotations of the magnets were considered in the simulations. States of the beam were examined when errors occurred in the magnets by the applying analytic fringe field model in TRACK code. The condition for the beam orbit was optimized by using correctors and profile monitors to correct the orbit. In this paper, we focus on the beam dynamics and the error studies dedicated to the MEBT beam line and show the optimized beam parameters for the MEBT.

  17. SU-E-T-635: Quantitative Study On Beam Flatness Variation with Beam Energy Change

    SciTech Connect

    Li, J S; Eldib, A; Ma, C; Lin, M

    2014-06-15

    Purpose: Beam flatness check has been proposed for beam energy check for photon beams with flattering filters. In this work, beam flatness change with beam energy was investigated quantitatively using the Monte Carlo method and its significance was compared with depth dose curve change. Methods: Monte Carlo simulations for a linear accelerator with flattering filter were performed with different initial electron energies for photon beams of 6MV and 10MV. Dose calculations in a water phantom were then perform with the phase space files obtained from the simulations. The beam flatness was calculated based on the dose profile at 10 cm depth for all the beams with different initial electron energies. The percentage depth dose (PDD) curves were also analyzed. The dose at 10cm depth (D10) and the ratio of the dose at 10cm and 20cm depth (D10/D20) and their change with the beam energy were calculated and compared with the beam flatness variation. Results: It was found that the beam flatness variation with beam energy change was more significant than the change of D10 and the ratio between D10 and D20 for both 6MV and 10MV beams. Half MeV difference on the initial electron beam energy brought in at least 20% variation on the beam flatness but only half percent change on the ratio of D10 and D20. The change of D10 or D20 alone is even less significant. Conclusion: The beam energy impact on PDD is less significant than that on the beam flatness. If the PDD is used for checking the beam energy, uncertainties of the measurement could possibly disguise its change. Beam flatness changes more significantly with beam energy and therefore it can be used for monitoring the energy change for photon beams with flattering filters. However, other factors which may affect the beam flatness should be watched as well.

  18. Angiotensin II-induced angiotensin II type I receptor lysosomal degradation studied by fluorescence lifetime imaging microscopy

    NASA Astrophysics Data System (ADS)

    Li, Hewang; Yu, Peiying; Felder, Robin A.; Periasamy, Ammasi; Jose, Pedro A.

    2009-02-01

    Upon activation, the angiotensin (Ang) II type 1 receptor (AT1Rs) rapidly undergoes endocytosis. After a series of intracellular processes, the internalized AT1Rs recycle back to the plasma membrane or are trafficked to proteasomes or lysosomes for degradation. We recently reported that AT1Rs degrades in proteasomes upon stimulation of the D5 dopamine receptor (D5R) in human renal proximal tubule and HEK-293 cells. This is in contrast to the degradation of AT1R in lysosomes upon binding Ang II. However, the dynamic regulation of the AT1Rs in lysosomes is not well understood. Here we investigated the AT1Rs lysosomal degradation using FRET-FLIM in HEK 293 cells heterologously expressing the human AT1R tagged with EGFP as the donor fluorophore. Compared to its basal state, the lifetime of AT1Rs decreased after a 5-minute treatment with Ang II treatment and colocalized with Rab5 but not Rab7 and LAMP1. With longer Ang II treatment (30 min), the AT1Rs lifetime decreased and co-localized with Rab5, as well as Rab7 and LAMP1. The FLIM data are corroborated with morphological and biochemical co-immunoprecipitation studies. These data demonstrate that Ang II induces the internalization of AT1Rs into early sorting endosomes prior to trafficking to late endosomes and subsequent degradation in lysosomes.

  19. [Lifetime prevalence and age of onset of mental disorders in Peru: results of the World Mental Health Study, 2005].

    PubMed

    Fiestas, Fabián; Piazza, Marina

    2014-01-01

    To determine the lifetime prevalence of 18 mental disorders and to establish the pattern that those disorders have with the age of onset in five cities of Peru. As part of the World Mental Health Survey, the study in Peru followed a probabilistic multistage sample of people between 18 and 65 years old in Lima, Chiclayo, Arequipa, Huancayo and Iquitos. The desktop version of the Composite International Diagnostic Interview (CIDI) was administered. The lifetime prevalence of at least one mental disorder was 29% (SE 1.2), and the prevalence of at least two or three was 10.5% (SE 0.7) and 4% (SE 0.4), respectively. Anxiety disorders were more common with 14.9% (SE 0.9) prevalence, followed by mood disorders with 8.2% (SE 0.5), impulse control disorders with 8.1% (SE 0.8), and substance use disorders (5.8%; SE 0.3). The age of onset was earlier for anxiety disorders (15 years old) and for impulse control disorders (20 years old). Younger respondents were more likely to have a mental disorder. Almost a third of the adult population of five cities in Peru has had some psychiatric disorder at a given time in their lives, and comorbidity is common. Most disorders begin before age 30.

  20. Ion induced modification in free volume in PN-6 and PES polymers by positron annihilation lifetime studies

    NASA Astrophysics Data System (ADS)

    Kumar, Rajesh; Prasad, Rajendra

    2007-03-01

    The irradiation of polymeric materials with swift heavy ions (SHI) results in a change of their free volume properties which have strong correlation with their macroscopic properties. Positron annihilation lifetime spectroscopy (PALS) has been developed into a powerful characterization tool for the study of free volume and free volume fraction in polymers. Polyamide nylon-6 (PN-6) and polyethersulphone (PES) films of thickness of 250 μm were irradiated with C5+ ions of energy 70 MeV from 15 UD Pelletron accelerator at Inter University Accelerator Centre (IUAC), New Delhi, India. PN-6 films were irradiated to the fluences of 1011, 1012 and 1013 ions/cm2 whereas PES films were irradiated to the fluences of 9.3 × 1011, 9.3 × 1012 and 1.2 × 1013 ions/cm2. Characterization of the effect of ion irradiation on free volume has been done by PALS. The average free volume and fractional free volume obtained from long lived component, attributed to ortho-positronium (o-Ps) lifetime, are found to decrease with the fluence in both the cases. With increasing fluence, scissioned segments cross-link randomly, resulting in a decrease of average free volume due to overlapping of tracks.

  1. Free volume evolution in 50 MeV Li3+ ion-irradiated polymers studied by positron annihilation lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Singh, Paramjit; Kumar, Rajesh; Prasad, Rajendra

    2013-02-01

    This article is aimed at studying the effect of ion irradiation on free volume of polyethersulphone (PES) and polyamide nylon-6 (PN-6) polymers by positron annihilation lifetime spectroscopy (PALS). Free volume properties of polymeric materials change with swift heavy ion irradiation. Free volume is found to have a strong correlation with the macroscopic properties of the polymer. PALS has recently emerged as a unique non-destructive and non-interfering nano-probe, capable of measuring the free volume hole size in polymers with high detection efficiency. PES and PN-6 polymer films of thickness of 250 μm were irradiated with Li3+ ions of energy 50 MeV from the 15 UD Pelletron accelerator at the Inter University Accelerator Centre, New Delhi, India. PES films were irradiated to the fluences of 1011, 1012, 1013 and 1014 ions/cm2, whereas PN-6 films were irradiated to the fluences of 1011, 1012 and 1013 ions/cm2. The average free volume and fractional free volume obtained from the long-lived component, attributed to ortho-positronium lifetime, are found to vary with the variation of fluence in both the cases.

  2. Lifetime Prevalence of Suicide Attempts Among Sexual Minority Adults by Study Sampling Strategies: A Systematic Review and Meta-Analysis

    PubMed Central

    Bogaert, Laura; Rhodes, Anne E.; Brennan, David J.; Gesink, Dionne

    2016-01-01

    Background. Previous reviews have demonstrated a higher risk of suicide attempts for lesbian, gay, and bisexual (LGB) persons (sexual minorities), compared with heterosexual groups, but these were restricted to general population studies, thereby excluding individuals sampled through LGB community venues. Each sampling strategy, however, has particular methodological strengths and limitations. For instance, general population probability studies have defined sampling frames but are prone to information bias associated with underreporting of LGB identities. By contrast, LGB community surveys may support disclosure of sexuality but overrepresent individuals with strong LGB community attachment. Objectives. To reassess the burden of suicide-related behavior among LGB adults, directly comparing estimates derived from population- versus LGB community–based samples. Search methods. In 2014, we searched MEDLINE, EMBASE, PsycInfo, CINAHL, and Scopus databases for articles addressing suicide-related behavior (ideation, attempts) among sexual minorities. Selection criteria. We selected quantitative studies of sexual minority adults conducted in nonclinical settings in the United States, Canada, Europe, Australia, and New Zealand. Data collection and analysis. Random effects meta-analysis and meta-regression assessed for a difference in prevalence of suicide-related behavior by sample type, adjusted for study or sample-level variables, including context (year, country), methods (medium, response rate), and subgroup characteristics (age, gender, sexual minority construct). We examined residual heterogeneity by using τ2. Main results. We pooled 30 cross-sectional studies, including 21 201 sexual minority adults, generating the following lifetime prevalence estimates of suicide attempts: 4% (95% confidence interval [CI] = 3%, 5%) for heterosexual respondents to population surveys, 11% (95% CI = 8%, 15%) for LGB respondents to population surveys, and 20% (95% CI

  3. Lifetime Prevalence of Suicide Attempts Among Sexual Minority Adults by Study Sampling Strategies: A Systematic Review and Meta-Analysis.

    PubMed

    Hottes, Travis Salway; Bogaert, Laura; Rhodes, Anne E; Brennan, David J; Gesink, Dionne

    2016-05-01

    Previous reviews have demonstrated a higher risk of suicide attempts for lesbian, gay, and bisexual (LGB) persons (sexual minorities), compared with heterosexual groups, but these were restricted to general population studies, thereby excluding individuals sampled through LGB community venues. Each sampling strategy, however, has particular methodological strengths and limitations. For instance, general population probability studies have defined sampling frames but are prone to information bias associated with underreporting of LGB identities. By contrast, LGB community surveys may support disclosure of sexuality but overrepresent individuals with strong LGB community attachment. To reassess the burden of suicide-related behavior among LGB adults, directly comparing estimates derived from population- versus LGB community-based samples. In 2014, we searched MEDLINE, EMBASE, PsycInfo, CINAHL, and Scopus databases for articles addressing suicide-related behavior (ideation, attempts) among sexual minorities. We selected quantitative studies of sexual minority adults conducted in nonclinical settings in the United States, Canada, Europe, Australia, and New Zealand. Random effects meta-analysis and meta-regression assessed for a difference in prevalence of suicide-related behavior by sample type, adjusted for study or sample-level variables, including context (year, country), methods (medium, response rate), and subgroup characteristics (age, gender, sexual minority construct). We examined residual heterogeneity by using τ(2). We pooled 30 cross-sectional studies, including 21,201 sexual minority adults, generating the following lifetime prevalence estimates of suicide attempts: 4% (95% confidence interval [CI] = 3%, 5%) for heterosexual respondents to population surveys, 11% (95% CI = 8%, 15%) for LGB respondents to population surveys, and 20% (95% CI = 18%, 22%) for LGB respondents to community surveys (Figure 1). The difference in LGB estimates by sample

  4. Beam-beam interaction study of medium energy eRHIC

    SciTech Connect

    Hao,Y.; Litvinenko, V. N.; Ptitsyn, V.

    2009-07-15

    Medium Energy eRHIC (MeRHIC), the first stage design of eRHIC, includes a multi-pass ERL that provides 4GeV high quality electron beam to collide with the ion beam of RHIC. It delivers a minimum luminosity of 10{sup 32} cm{sup -2}s{sup -1}. Beam-beam effects present one of major factors limiting the luminosity of colliders. In this paper, both beam-beam effects on the electron beam and the proton beam in MeRHIC are investigated. The beam-beam interaction can induce a head-tail type instability of the proton beam referred to as the kink instability. Thus, beam stability conditions should be established to avoid proton beam loss. Also, the electron beam transverse disruption by collisions has to be evaluated to ensure that the beam quality is good enough for the energy recovery pass. The relation of proton beam stability, electron disruption and consequential luminosity are carried out after thorough discussion.

  5. Study of longitudinal dynamics in space-charge dominated beams

    NASA Astrophysics Data System (ADS)

    Tian, Kai

    from the 6-D phase space measurement has been used as initial conditions in computer simulations in order to explore the cause of discrepancies we have observed earlier between the experimental and theoretical models. After extensive simulation studies, we find that the beam loss inside the perturbation due to mismatch or misalignment is an important factor that needs to be included in the models for better reliability.

  6. Neutron Transport Simulations for NIST Neutron Lifetime Experiment

    NASA Astrophysics Data System (ADS)

    Li, Fangchen; BL2 Collaboration Collaboration

    2016-09-01

    Neutrons in stable nuclei can exist forever; a free neutron lasts for about 15 minutes on average before it beta decays to a proton, an electron, and an antineutrino. Precision measurements of the neutron lifetime test the validity of weak interaction theory and provide input into the theory of the evolution of light elements in the early universe. There are two predominant ways of measuring the neutron lifetime: the bottle method and the beam method. The bottle method measures decays of ultracold neutrons that are stored in a bottle. The beam method measures decay protons in a beam of cold neutrons of known flux. An improved beam experiment is being prepared at the National Institute of Science and Technology (Gaithersburg, MD) with the goal of reducing statistical and systematic uncertainties to the level of 1 s. The purpose of my studies was to develop computer simulations of neutron transport to determine the beam collimation and study the neutron distribution's effect on systematic effects for the experiment, such as the solid angle of the neutron flux monitor. The motivation for the experiment and the results of this work will be presented. This work was supported, in part, by a Grant to Gettysburg College from the Howard Hughes Medical Institute through the Precollege and Undergraduate Science Education Program.

  7. Singlet oxygen phosphorescence lifetime imaging based on a fluorescence lifetime imaging microscope.

    PubMed

    Tian, Wenming; Deng, Liezheng; Jin, Shengye; Yang, Heping; Cui, Rongrong; Zhang, Qing; Shi, Wenbo; Zhang, Chunlei; Yuan, Xiaolin; Sha, Guohe

    2015-04-09

    The feasibility of singlet oxygen phosphorescence (SOP) lifetime imaging microscope was studied on a modified fluorescence lifetime imaging microscope (FLIM). SOP results from the infrared radiative transition of O2(a(1)Δg → X(3)Σg(-)) and O2(a(1)Δg) was produced in a C60 powder sample via photosensitization process. To capture the very weak SOP signal, a dichroic mirror was placed between the objective and tube lens of the FLIM and used to divide the luminescence returning from the sample into two beams: the reflected SOP beam and the transmitted photoluminescence of C60 (C60-PL) beam. The C60-PL beam entered the scanner of the FLIM and followed the normal optical path of the FLIM, while the SOP steered clear of the scanner and directly entered a finely designed SOP detection channel. Confocal C60-PL images and nonconfocal SOP images were then simultaneously obtained by using laser-scanning mode. Experimental results show that (1) under laser-scanning mode, the obstacle to confocal SOP imaging is the infrared-incompatible scanner, which can be solved by using an infrared-compatible scanner. Confocal SOP imaging is also expected to be realized under stage-scanning mode when the laser beam is parked and meanwhile a pinhole is added into the SOP detection channel. (2) A great challenge to SOP imaging is its extraordinarily long imaging time, and selecting only a few interesting points from fluorescence images to measure their SOP time-dependent traces may be a correct compromise.

  8. Confined water in controlled pore glass CPG-10-120 studied by positron annihilation lifetime spectroscopy and differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Šauša, O.; Mat'ko, I.; Illeková, E.; Macová, E.; Berek, D.

    2015-06-01

    The solidification and melting of water confined in the controlled pore glass (CPG) with average pore size 12.6 nm has been studied by differential scanning calorimetry (DSC) and positron annihilation lifetime spectroscopy (PALS). The fully-filled sample of CPG by water as well as the samples of CPG with different content of water were used. The measurements show the presence of amorphous and crystalline phases of water in this type and size of pores, freezing point depression of a confined liquid and presence of certain transitions at lower temperatures, which could be detected only for cooling regime. The localization of confined water in the partially filled pores of CPG at room temperature was studied.

  9. A Case Study in Proton Pencil-Beam Scanning Delivery

    SciTech Connect

    Kooy, Hanne M.; Clasie, Benjamin M.; Lu, H.-M.; Madden, Thomas M.; Bentefour, Hassan; Depauw, Nicolas M.S.; Adams, Judy A.; Trofimov, Alexei V.; Demaret, Denis; Delaney, Thomas F.; Flanz, Jacob B.

    2010-02-01

    Purpose: We completed an implementation of pencil-beam scanning (PBS), a technology whereby a focused beam of protons, of variable intensity and energy, is scanned over a plane perpendicular to the beam axis and in depth. The aim of radiotherapy is to improve the target to healthy tissue dose differential. We illustrate how PBS achieves this aim in a patient with a bulky tumor. Methods and Materials: Our first deployment of PBS uses 'broad' pencil-beams ranging from 20 to 35 mm (full-width-half-maximum) over the range interval from 32 to 7 g/cm{sup 2}. Such beam-brushes offer a unique opportunity for treating bulky tumors. We present a case study of a large (4,295 cc clinical target volume) retroperitoneal sarcoma treated to 50.4 Gy relative biological effectiveness (RBE) (presurgery) using a course of photons and protons to the clinical target volume and a course of protons to the gross target volume. Results: We describe our system and present the dosimetry for all courses and provide an interdosimetric comparison. Discussion: The use of PBS for bulky targets reduces the complexity of treatment planning and delivery compared with collimated proton fields. In addition, PBS obviates, especially for cases as presented here, the significant cost incurred in the construction of field-specific hardware. PBS offers improved dose distributions, reduced treatment time, and reduced cost of treatment.

  10. Experimental Study of Electron Beam Focusing Through Overdense Plasma Lenses

    NASA Astrophysics Data System (ADS)

    Govil, R.; Wheeler, S. J.; Leemans, W. P.

    1997-05-01

    A comprehensive experimental study of focusing of relativistic electron beams with overdense and underdense plasma lenses is being conducted at the Beam Test Facility at LBNL footnote W. Leemans et al., Proc. 1993 Part. Accel. Conf., 83 (1993).. Short (15ps rms) electron bunches, from the 50 MeV LBNL Advanced Light Source injector are transported through laser produced plasmas. The electron beam spot size and divergence at the plasma lens is adjusted using quadrupoles. The plasmas are 1-5 cm long with densities of 10^13-10^14 cm-3. By changing the laser intensity and shape, the plasma density and profile can be controlled. This allows for exploration of both the charge and current compensation regimes, by changing the ratio of the plasma wavenumber, k_p, to the electron beam size, σ_r. Experimental results on the production of plasmas through two-photon UV ionization and electron beam diagnostics have been presented earlier (R. Govil et al., Proc. 1995 Part. Accel. Conf., 776 (1995).). Here we present results from the experimentally observed plasma focusing for overdense lenses in charge and current compensation regimes. Detailed interferometric results from the production of highly overdense plasmas are also discussed.

  11. Simulation study of dynamic aperture with head-on beam-beam compensation in the RHIC

    SciTech Connect

    Luo, Y.; Fischer, W.

    2010-08-01

    In this note we summarize the calculated 10{sup 6} turn dynamic apertures with the proposed head-on beam-beam compensation in the Relativistic Heavy Ion Collider (RHIC). To compensate the head-on beam-beam effect in the RHIC 250 GeV polarized proton run, we are planning to introduce a DC electron beam with the same transverse profile as the proton beam to collide with the proton beam. Such a device to provide the electron beam is called an electron lens (e-lens). In this note we first present the optics and beam parameters and the tracking setup. Then we compare the calculated dynamic apertures without and with head-on beam-beam compensation. The effects of adjusted phase advances between IP8 and the center of e-lens and second order chromaticity correction are checked. In the end we will scan the proton and electron beam parameters with head-on beam-beam compensation.

  12. Computational challenges for beam-beam simulation for RHIC

    SciTech Connect

    Luo, Y.; Fischer, W.

    2010-10-01

    In this article we will review the computational challenges in the beam-beam simulation for the polarized proton run of the Relativistic Heavy Ion Collider (RHIC). The difficulties in our multi-particle and million turn tracking to calculate the proton beam lifetime and proton beam emittance growth due to head-on beam-beam interaction and head-on beam-beam compensation are presented and discussed. Solutions to obtain meaningful physics results from these trackings are proposed and tested. In the end we will present the progress in the benchmarking of the RHIC operational proton beam lifetime.

  13. Fermilab Booster Transition Crossing Simulations and Beam Studies

    SciTech Connect

    Bhat, C. M.; Tan, C. Y.

    2016-01-01

    The Fermilab Booster accelerates beam from 400 MeV to 8 GeV at 15 Hz. In the PIP (Proton Improvement Plan) era, it is required that Booster deliver 4.2 x $10^{12}$ protons per pulse to extraction. One of the obstacles for providing quality beam to the users is the longitudinal quadrupole oscillation that the beam suffers from right after transition. Although this oscillation is well taken care of with quadrupole dampers, it is important to understand the source of these oscillations in light of the PIP II requirements that require 6.5 x $10^{12}$ protons per pulse at extraction. This paper explores the results from machine studies, computer simulations and solutions to prevent the quadrupole oscillations after transition.

  14. High Brightness Electron Beam Studies at the NSLS SDL

    SciTech Connect

    Qian,H.; Hidaka, Y.; Murphy, J. B.; Podobedov, B.; Seletskiy, S.; Shen, Y.; Yang, X.; Wang, X. J.; Tang, C. X.

    2009-05-04

    Experimental optimization of electron beam brightness at the NSLS SDL is reported in this paper. Using a high quantum efficiency (QE) Mg metal cathode and the S-band BNL-type RF gun, we have systematically studied electron beams transverse and longitudinal emittance. The measured thermal emittance for the Mg cathode is 0.85{+-}0.04 mm-mrad/mm, which contradicts the current thermal emittance model. For a 50 pC beam, measured normalized transverse and longitudinal RMS emittance are 0.6 mm-mrd and 5.2 ps-keV, respectively. The smallest projected transverse emittance observed for a 20 pC charge is 0.15 {+-} 0.02 mm-mrad.

  15. Spheromak Energy Transport Studies via Neutral Beam Injection

    SciTech Connect

    McLean, H S; Hill, D N; Wood, R D; Jayakumar, J; Pearlstein, L D

    2008-02-11

    Results from the SSPX spheromak experiment provide strong motivation to add neutral beam injection (NBI) heating. Such auxiliary heating would significantly advance the capability to study the physics of energy transport and pressure limits for the spheromak. This LDRD project develops the physics basis for using NBI to heat spheromak plasmas in SSPX. The work encompasses three activities: (1) numerical simulation to make quantitative predictions of the effect of adding beams to SSPX, (2) using the SSPX spheromak and theory/modeling to develop potential target plasmas suitable for future application of neutral beam heating, and (3) developing diagnostics to provide the measurements needed for transport calculations. These activities are reported in several publications.

  16. Studies of polarized beam acceleration and Siberian Snakes

    SciTech Connect

    Lee, S.Y.

    1992-12-31

    We studied depolarization mechanisms of polarized proton acceleration in high energy accelerators with snakes and found that the perturbed spin tune due to the imperfection resonance plays an important role in beam depolarization at snake resonances. We also found that even order snake resonances exist in the overlapping intrinsic and imperfection resonances. Due to the perturbed spin tune of imperfection resonances, each snake resonance splits into two. Thus the available betatron tune space becomes smaller. Some constraints on polarized beam colliders were also examined.

  17. Theoretical study of longitudinal beam splitting and related phenomena

    SciTech Connect

    Ellison, J.; Shih, H.J.; Kummer, M.

    1993-10-01

    A recent experiment at the Indiana University Cyclotron Facility (IUCF) with electron cooling showed that rf phase modulation near 1:1 resonance leads to longitudinal beam splitting. Here we explain this by applying the method of averaging, a powerful tool from the study of dynamical systems, to the underlying equation of motion -- a pendulum equation with small damping and periodic forcing. The beam splitting is explained by showing that the associated Poincare map has two attracting fixed points, each with a well-defined basin of attraction. Our approach can be immediately applied to other accelerator physics problems governed by a similar equation.

  18. Theoretical study of longitudinal beam splitting and related phenomena

    SciTech Connect

    Ellison, J.A.; Shih, H. ); Kummer, M. )

    1994-03-01

    A recent experiment at the Indiana University Cyclotron Facility with electron cooling showed that rf phase modulation near the 1:1 resonance leads to longitudinal beam splitting. Here we explain this by applying the method of averaging, a powerful tool from the study of dynamical systems, to the underlying equation of motion---a pendulum equation with small damping and periodic forcing. The beam splitting is explained by showing that the associated Poincare map has two attracting fixed points, each with a well-defined basin of attraction. Our approach can be immediately applied to other accelerator-physics problems governed by a similar equation.

  19. Genome-wide association study for lactation persistency, female fertility, longevity, and lifetime profit index traits in Holstein dairy cattle.

    PubMed

    Nayeri, S; Sargolzaei, M; Abo-Ismail, M K; Miller, S; Schenkel, F; Moore, S S; Stothard, P

    2017-02-01

    Female fertility in Holstein cattle can decline when intense genetic selection is placed on milk production. One approach to improving fertility is to identify the genomic regions and variants affecting fertility traits and then incorporate this knowledge into selection decisions. The objectives of this study were to identify or refine the positions of the genomic regions associated with lactation persistency, female fertility traits (age at first service, cow first service to conception, heifer and cow nonreturn rates), longevity traits (herd life, indirect herd life, and direct herd life), and lifetime profit index in the North American Holstein dairy cattle population. A genome-wide association study was performed for each trait, using a single SNP (single nucleotide polymorphism) regression mixed linear model and imputed high-density panel (777k) genotypes. No associations were identified for fertility traits. Several peak regions were detected for lifetime profit index, lactation persistency, and longevity. The results overlap with previous findings and identify some novel regions for lactation persistency. Previously proposed causative and candidate genes supported by this work include DGAT1, GRINA, and CPSF1, whereas new candidate genes are SLC2A4RG and THRB. Thus, the chromosomal regions identified in this study not only confirm several previous findings but also highlight new regions that may contribute to genetic variation in lactation persistency and longevity-associated traits in dairy cattle. The Authors. Published by the Federation of Animal Science Societies and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

  20. A study of inter-crystallite spaces in some polycrystalline inorganic systems using positron annihilation lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Shantarovich, V. P.; Suzuki, T.; Ito, Y.; Kondo, K.; Gustov, V. W.; Melikhov, I. V.; Berdonosov, S. S.; Ivanov, L. N.; Yu, R. S.

    2007-02-01

    Positron annihilation lifetime spectroscopy (PALS) was used for calculation of number density and effective sizes of free volume holes (inter-crystallite spaces) in polycrystal CaSO 4, CaCO 3 (vaterit) and Ca 10(PO 4) 6(OH) 2 (apatite). The effect of substitution of two-valence Ca(II) for three-valence Eu(III) on annihilation characteristics of apatite, studied together with the data on thermo-stimulated luminescence (TSL) and low-temperature sorption of gas (N 2), helped to elucidate mechanism of positronium atom (Ps) localization in the free volume holes and perform corresponding calculations. It came out that PALS is more sensitive to inter-crystallite sites (10 16 cm -3) in polycrystallites than to the free volume holes in polymer glasses (10 19 cm -3). This is due to higher mobility of the precursor of localized Ps in crystallites.

  1. Optimization of parameters of a surface-electrode ion trap and experimental study of influences of surface on ion lifetime

    NASA Astrophysics Data System (ADS)

    Ou, BaoQuan; Zhang, Jie; Zhang, XinFang; Xie, Yi; Chen, Ting; Wu, ChunWang; Wu, Wei; Chen, PingXing

    2016-12-01

    In this paper we report the optimal design and fabrication of a gold-on-silica linear segmented surface-electrode ion trap. By optimizing the thickness and width of the electrodes, we improved the trapping ability and trap scalability. By using some practical experimental operation methods, we successfully minimized the trap heating rate. Consequently, we could trap a string of up to 38 ions, and a zigzag structure with 24 ions, and transport two trapped ions to different zones. We also studied the influences of the ion chip surface on the ion lifetime. The excellent trapping ability and flexibility of operation of the planar ion trap shows that it has high feasibility for application in the development a practical quantum information processor or quantum simulator.

  2. Hydrolytic Degradation of Poly(L-Lactide-co-Glycolide) Studied by Positron Annihilation Lifetime Spectroscopy and Other Techniques

    NASA Astrophysics Data System (ADS)

    Pamuła, E.; Dryzek, E.; Dobrzyński, P.

    2006-11-01

    Changes of the poly(L-lactide-co-glycolide) structure as a function of degradation time in phosphate-buffered saline for 7 weeks were investigated by gel permeation chromatography, differential scanning calorimetry, nuclear magnetic resonance (1H NMR), and positron annihilation lifetime spectroscopy. Surface properties as wettability by sessile drop and topography by atomic force microscopy were also characterized. Chain-scission of polyester bonds in hydrolysis reaction causes a quite uniform decrease in molecular weight, and finally results in an increase in semicrystallinity. Molecular composition of the copolymer and water contact angle do not change considerably during degradation time. Atomic force microscopy studies suggest that the copolymer degrades by "in bulk" mechanism. The average size of the molecular-level free volume holes declines considerably after one week of degradation and remains constant till the sixth week of degradation. The free volume fraction decreases as a function of degradation time.

  3. Molecular Beam Studies of Low Energy Reactions.

    DTIC Science & Technology

    1983-03-31

    COMPLETING PORN . REPORT NUMBER 1 2. GOVT ACCESSION NO. S. RECIPIENT’S CATALOG NUMBER A D A Oaq J- 4. TITLE (And Subtitle) . TYPE OF REPORT & PERIOD COVERED...Gatlinburg, Tenn . in 1981. 2+ c) Studies were made of the charge transfer reaction Ar + Ar 4 2+ Ar + Ar at relative energies from 2 to 1000 eV. Reasons for

  4. Nuclear Structure Studies with Polarized Radioactive Beams

    SciTech Connect

    Asahi, K.; Uchida, M.; Inoue, T.; Hatakeyama, M.; Kagami, S.; Hasama, Y.; Suzuki, K.; Ueno, H.; Nagatomo, T.; Yoshimi, A.; Kameda, D.; Ishihara, M.; Shimada, K.; Nagae, D.; Murata, J.; Narita, K.; Kawamura, H.

    2009-08-04

    Nuclear moment studies on nuclei far from the beta-stability line, performed by taking advantage of the projectile fragmentation reaction, are reviewed. A method to produce spin polarization/alignment in the projectile fragments was developed and utilized for the beta-NMR/NQR measurements. Several new findings in nuclear structure physics were obtained from the nuclear moment experiments done with these techniques.

  5. Lifetime risk of stroke and impact of hypertension: estimates from the adult health study in Hiroshima and Nagasaki.

    PubMed

    Takahashi, Ikuno; Geyer, Susan M; Nishi, Nobuo; Ohshita, Tomohiko; Takahashi, Tetsuya; Akahoshi, Masazumi; Fujiwara, Saeko; Kodama, Kazunori; Matsumoto, Masayasu

    2011-05-01

    Very few reports have been published on lifetime risk (LTR) of stroke by blood pressure (BP) group. This study included participants in the Radiation Effects Research Foundation Adult Health Study who have been followed up by biennial health examinations since 1958. We calculated the LTR of stroke for various BP-based groups among 7847 subjects who had not been diagnosed with stroke before the index age of 55 years using cumulative incidence analysis adjusting for competing risks. By 2003, 868 subjects had suffered stroke (512 (58.9%) were women and 542 (62.4%) experienced ischemic stroke). BP was a significant factor in determining risk of stroke for men and women, with distributions of cumulative risk for stroke significantly different across BP groups. The LTR of all-stroke for normotension (systolic BP/diastolic BP < 120/80 mm Hg), prehypertension (120-139/80-89 mm Hg), stage 1 hypertension (140-159/90-99 mm Hg) and stage 2 hypertension (> 160/100 mm Hg) were 13.8-16.9-25.8-25.8% in men and 16.0-19.9-24.0-30.5% in women, respectively (P < 0.001 among BP groups in both sexes). The estimates did not differ significantly (P = 0.16) between normotensive and prehypertensive subjects. One in five Japanese atomic bomb survivor subjects experienced stroke over their lifetime from the age of 55 years. Long-term stroke risks were elevated in those with hypertension (> 140/90 mm Hg) at any of the index ages of 45, 55, 65 and 75 years.

  6. Lifetime cumulative risk factors predict cardiovascular disease mortality in a 50-year follow-up study in Finland.

    PubMed

    Reinikainen, Jaakko; Laatikainen, Tiina; Karvanen, Juha; Tolonen, Hanna

    2015-02-01

    Systolic blood pressure, total cholesterol and smoking are known predictors of cardiovascular disease (CVD) mortality. Less is known about the effect of lifetime accumulation and changes of risk factors over time as predictors of CVD mortality, especially in very long follow-up studies. Data from the Finnish cohorts of the Seven Countries Study were used. The baseline examination was in 1959 and seven re-examinations were carried out at approximately 5-year intervals. Cohorts were followed up for mortality until the end of 2011. Time-dependent Cox models with regular time-updated risk factors, time-dependent averages of risk factors and latest changes in risk factors, using smoothing splines to discover nonlinear effects, were used to analyse the predictive effect of risk factors for CVD mortality. A model using cumulative risk factors, modelled as the individual-level averages of several risk factor measurements over time, predicted CVD mortality better than a model using the most recent measurement information. This difference seemed to be most prominent for systolic blood pressure. U-shaped effects of the original predictors can be explained by partitioning a risk factor effect between the recent level and the change trajectory. The change in body mass index predicted the risk although body mass index itself did not. The lifetime accumulation of risk factors and the observed changes in risk factor levels over time are strong predictors of CVD mortality. It is important to investigate different ways of using the longitudinal risk factor measurements to take full advantage of them. © The Author 2014; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association.

  7. Commisioning of the second Tevatron electron lens and beam study results

    SciTech Connect

    Kamerdzhiev, V.; Fellenz, B.; Hively, R.; Kuznetsov, G.; Olson, M.; Pfeffer, H.; Saewert, G.; Scarpine, V.; Shiltsev, V.; Zhang, X.L.; /Fermilab

    2007-06-01

    In the framework of Fermilab's Beam-Beam Compensation (BBC) project, the 2nd Tevatron Electron Lens (TEL2) was installed in the Tevatron during Spring 2006 shutdown. It was successfully commissioned and a series of beam studies has been carried out in single bunch and all-bunch modes. The paper describes TEL2 commissioning and beam studies results.

  8. Cluster Beam Studies of Metal Combustion

    DTIC Science & Technology

    1992-07-21

    begun the first high-quality experiments on reactions of clean boron surfaces. This work is important because it directly measures the elementary...studies. (See Fig. 1 for a schematic diagram of one of the instruments). * Measurements of reaction cross sections over a wide collision energy range... Measurement of exciton structure near the boron K-edge. * High level ab iniflo calculation of boron duster ion structures and properties to compliment

  9. Parametric study of beam refraction problems across laser anemometer windows

    NASA Technical Reports Server (NTRS)

    Owen, A. K.

    1986-01-01

    The experimenter is often required to view flows through a window with a different index of refraction than either the medium being observed or the medium that the laser anemometer is immersed in. The refraction that occurs at the window surfaces may lead to undesirable changes in probe volume position or beam crossing angle and can lead to partial or complete beam uncrossing. This report describes the results of a parametric study of this problem using a ray tracing technique to predict these changes. The windows studied were a flat plate and a simple cyclinder. For the flat-plate study: (1) surface thickness, (2) beam crossing angle, (3) bisecting line - surface normal angle, and (4) incoming beam plane surface orientation were varied. For the cylindrical window additional parameters were also varied: (1) probe volume immersion, (2) probe volume off-radial position, and (3) probe volume position out of the R-theta plane of the lens. A number of empirical correlations were deduced to aid the interested reader in determining the movement, uncrossing, and change in crossing angle for a particular situation.

  10. Beam Dynamics Studies on the ISAC RFQ at TRIUMF

    NASA Astrophysics Data System (ADS)

    Koscielniak, S.; Laxdal, R. E.; Lee, R.; Root, L.

    1997-05-01

    An 8 m long split-ring RFQ linac is being constructed at TRIUMF as part of the ISAC radioactive beam project. The RFQ is designed to accelerate unstable nuclei with A/q >= 1/30 from 2 keV/u to 150 keV/u. Initially a 2.8 m long section of the RFQ is being constructed for beam tests to 53 keV/u. Several unusual beam dynamics studies have been pursued during the latter stages of the accelerator design. To furnish engineering alignment tolerances, particle tracking in the 12-term potential was performed to estimate the RFQ performance (transmission and emittance) with respect to various types of vane displacement errors. The results compare favorably with a simple analytical model. In order to explore fringe field effects, particle tracking studies through computed three-dimensional fields at the RFQ entrance and exit were made to optimize the radial matching section to the LEBT optics, and to appraise the value of a transition cell(Crandall: Proc. Linac '94, pp.227-229.) in mitigating exit-energy variability. The commissioning strategy and testing procedure developed for the initial 2.8 m section of the RFQ have been evaluated by extensive simulation studies. In this paper we describe the methods and results of the beam dynamics simulations and summarize final specifications for the RFQ.

  11. Study of a multi-beam accelerator driven thorium reactor

    SciTech Connect

    Ludewig, H.; Aronson, A.

    2011-03-01

    The primary advantages that accelerator driven systems have over critical reactors are: (1) Greater flexibility regarding the composition and placement of fissile, fertile, or fission product waste within the blanket surrounding the target, and (2) Potentially enhanced safety brought about by operating at a sufficiently low value of the multiplication factor to preclude reactivity induced events. The control of the power production can be achieved by vary the accelerator beam current. Furthermore, once the beam is shut off the system shuts down. The primary difference between the operation of an accelerator driven system and a critical system is the issue of beam interruptions of the accelerator. These beam interruptions impose thermo-mechanical loads on the fuel and mechanical components not found in critical systems. Studies have been performed to estimate an acceptable number of trips, and the value is significantly less stringent than had been previously estimated. The number of acceptable beam interruptions is a function of the length of the interruption and the mission of the system. Thus, for demonstration type systems and interruption durations of 1sec < t < 5mins, and t > 5mins 2500/yr and 50/yr are deemed acceptable. However, for industrial scale power generation without energy storage type systems and interruption durations of t < 1sec., 1sec < t < 10secs., 10secs < t < 5mins, and t > 5mins, the acceptable number of interruptions are 25000, 2500, 250, and 3 respectively. However, it has also been concluded that further development is required to reduce the number of trips. It is with this in mind that the following study was undertaken. The primary focus of this study will be the merit of a multi-beam target system, which allows for multiple spallation sources within the target/blanket assembly. In this manner it is possible to ameliorate the effects of sudden accelerator beam interruption on the surrounding reactor, since the remaining beams will still

  12. Theoretical studies of a molecular beam generator

    NASA Technical Reports Server (NTRS)

    Heinbockel, John

    1994-01-01

    At present no adequate computer code exists for predicting the effects of thermal nonequilibrium on the flow quality of a converging-diverging N2 nozzle. It is the purpose of this research to develop such a code and then perform parametric studies to determine the effects of intermolecular forces (high gas pressure) and thermal nonequilibrium (the splitting of temperature into a vibrational and rotational-translational excitation) upon the flow quality. The two models to be compared are given. Appendix A contains nomenclature and additional relationships.

  13. Non Linear Beam Dynamics Studies at SPEAR

    SciTech Connect

    Terebilo, A.; Pellegrini, C.; Cornacchia, M.; Corbett, J.; Martin, D.; /SLAC

    2011-09-12

    The frequency map analysis of a Hamiltonian system recently introduced to accelerators physics in combination with turn-by-turn phase space measurements opens new experimental opportunities for studying non linear dynamic in storage rings. In this paper we report on the experimental program at SPEAR having the goal of measuring the frequency map of the machine. In this paper we discuss the accuracy of the instantaneous tune extraction from experimental data and demonstrate the possibility of the frequency map measurement. The instantaneous tune extraction technique can be applied to experimental tracking data with reasonable accuracy. Frequency map can be experimentally determined using the existing turn-by-turn phase space measurement techniques and NAFF instantaneous tune extraction.

  14. RADIATIVE LIFETIMES OF V I AND V II

    SciTech Connect

    Den Hartog, E. A.; Lawler, J. E.; Wood, M. P. E-mail: jelawler@wisc.edu

    2014-11-01

    New radiative lifetimes are reported for 168 levels of V I ranging in energy from 18086 cm{sup –1} to 47702 cm{sup –1}, and for 31 levels of V II ranging in energy from 34593 cm{sup –1} to 47420 cm{sup –1}. These lifetimes are measured using time-resolved laser-induced fluorescence on a slow atomic/ionic beam as part of an ongoing study of the radiative properties of the iron group elements. All but two of the V II lifetimes have been measured before using modern laser-based methods, but a large fraction of the V I lifetimes are reported here for the first time. Comparison to earlier measurements is discussed. These new lifetimes are, for the most part, accurate to ±5%. They will be combined with branching fraction measurements to produce a large set of transition probabilities for V I and V II which are needed by the astrophysics community for stellar abundance determinations.

  15. Fast beam studies of free radical photodissociation

    SciTech Connect

    Cyr, Douglas Robert

    1993-11-01

    The photodissociation of free radicals is studied in order to characterize the spectroscopy and dissociation dynamics of the dissociative electronic states in these species. To accomplish this, a novel method of radical production, based on the photodetachment of the corresponding negative ion, has been combined with a highly complementary form of photofragment translational spectroscopy. The optical spectroscopy of transitions to dissociative states is determined by monitoring the total photofragment yield as a function of dissociation photon energy. Branching ratios to various product channels, internal energy distributions of the fragments, bond dissociation energies, and the translational energy-dependent photofragment recoil angular distributions are then determined at selected excitation energies. A detailed picture of the dissociation dynamics can then be formulated, allowing insight concerning the interactions of potential energy surfaces involved in the dissociation. After an introduction to the concepts and techniques mentioned above, the experimental apparatus used in these experiments is described in detail. The basis and methods used in the treatment of data, especially in the dissociation dynamics experiments, are then put forward.

  16. Lifetime carcinogenesis studies of amosite asbestos (Case No. 121-72-73-5) in Syrian golden hamsters (feed studies). Technical report series

    SciTech Connect

    Not Available

    1983-11-01

    Carcinogenesis studies of amosite asbestos were conducted by administering diets containing 1% of the asbestos in pellets from the conception of the mothers through the lifetime of male and female Syrian golden hamsters. Control groups consisted of 127 male and 126 female hamsters and the amosite asbestos group consisted of 252 male and 254 female hamsters. No adverse effect on body-weight gain or survival was observed from treatment with amosite asbestos. Neither of the amosite asbestos groups showed increased neoplasia in any organ or tissue compared to the control groups. Under the conditions of these studies, the ingestion of amosite asbestos at a level of 1% in the diet for their lifetime was not toxic and did not cause a carcinogenic response in male and female Syrian golden hamsters.

  17. A simulation study of radial expansion of an electron beam injected into an ionospheric plasma

    NASA Technical Reports Server (NTRS)

    Koga, J.; Lin, C. S.

    1994-01-01

    Injections of nonrelativistic electron beams from a finite equipotential conductor into an ionospheric plasma have been simulated using a two-dimensional electrostatic particle code. The purpose of the study is to survey the simulation parameters for understanding the dependence of beam radius on physical variables. The conductor is charged to a high potential when the background plasma density is less than the beam density. Beam electrons attracted by the charged conductor are decelerated to zero velocity near the stagnation point, which is at a few Debye lengths from the conductor. The simulations suggest that the beam electrons at the stagnation point receive a large transverse kick and the beam expands radially thereafter. The buildup of beam electrons at the stagnation point produces a large electrostatic force responsible for the transverse kick. However, for the weak charging cases where the background plasma density is larger than the beam density, the radial expansion mechanism is different; the beam plasma instability is found to be responsible for the radial expansion. The simulations show that the electron beam radius for high spacecraft charging cases is of the order of the beam gyroradius, defined as the beam velocity divided by the gyrofrequency. In the weak charging cases, the beam radius is only a fraction of the beam gyroradius. The parameter survey indicates that the beam radius increases with beam density and decreases with magnetic field and beam velocity. The beam radius normalized by the beam gyroradius is found to scale according to the ratio of the beam electron Debye length to the ambient electron Debye length. The parameter dependence deduced would be useful for interpreting the beam radius and beam density of electron beam injection experiments conducted from rockets and the space shuttle.

  18. Recent observations of beam plasma interactions in the ionosphere and a comparison with laboratory studies of the beam plasma discharge

    NASA Technical Reports Server (NTRS)

    Bernstein, W.; Kellogg, P. J.; Monson, S. J.; Holzworth, R. H.; Whalen, B. A.

    1982-01-01

    Experimental results from an electron beam injection rocket flight (27:010 AE) launched into an active aurora are summarized. The rocket carried an accelerator which injected programmed electron beams of less than 100 ma at 2 and 4 kV into the ionospheric plasma over the altitude range 120-240 km. A major objective of the experiment was the study of beam-plasma interactions and the possible identification of the ignition of the beam-plasma discharge (BPD) which had been intensively studied in the laboratory. A qualitative assessment of the data indicates that BPD ignition was produced by both 10 ma and Im beams at 2 and 4 kV. Many of the observed characteristics are similar to the BPD characteristics observed in the laboratory.

  19. Recent observations of beam plasma interactions in the ionosphere and a comparison with laboratory studies of the beam plasma discharge

    NASA Technical Reports Server (NTRS)

    Bernstein, W.; Kellogg, P. J.; Monson, S. J.; Holzworth, R. H.; Whalen, B. A.

    1982-01-01

    Experimental results from an electron beam injection rocket flight (27:010 AE) launched into an active aurora are summarized. The rocket carried an accelerator which injected programmed electron beams of less than 100 ma at 2 and 4 kV into the ionospheric plasma over the altitude range 120-240 km. A major objective of the experiment was the study of beam-plasma interactions and the possible identification of the ignition of the beam-plasma discharge (BPD) which had been intensively studied in the laboratory. A qualitative assessment of the data indicates that BPD ignition was produced by both 10 ma and Im beams at 2 and 4 kV. Many of the observed characteristics are similar to the BPD characteristics observed in the laboratory.

  20. A study on beam homogeneity for a Siemens Primus linac.

    PubMed

    Cutanda Henriquez, F; Vargas-Castrillón, S T

    2007-06-01

    Asymmetric offset fields are an important tool for radiotherapy and their suitability for treatment should be assessed. Dose homogeneity for highly asymmetric fields has been studied for a Siemens PRIMUS clinical linear accelerator. Profiles and absolute dose have been measured in fields with two jaws at maximal position (20 cm) and the other two at maximal overtravel (10 cm), corresponding to 10 cm x 10 cm fields with extreme offset. Measured profiles have a marked decreasing gradient towards the beam edge, making these fields unsuitable for treatments. The flattening filter radius is smaller than the primary collimator aperture, and this creates beam inhomogeneities that affect large fields in areas far from the collimator axis, and asymmetric fields with large offset. The results presented assess the effect that the design of the primary collimator and flattening filter assembly has on beam homogeneity. This can have clinical consequences for treatments involving fields that include these inhomogeneous areas. Comparison with calculations from a treatment planning system, Philips Pinnacle v6.3, which computes under the hypotheses of a uniformly flattened beam, results in severe discrepancies.

  1. Experimental Studies of Electrons in a Heavy-Ion Beam

    SciTech Connect

    Molvik, A W; Seidl, P A; Bieniosek, F M; Cohen, R H; Faltens, A; Friedman, A; Covo, M K; Lund, S M; Prost, L

    2004-06-23

    Electron cloud effects, ECEs, are normally a problem only in ring accelerators. However, heavy-ion induction linacs for inertial fusion energy have an economic incentive to fit beam tubes tightly to intense beams. This places them at risk from electron clouds produced by emission of electrons and gas from walls. We have measured electron and gas emission from 1 MeV K{sup +} impact on surfaces near grazing incidence on the High-Current Experiment (HCX) at LBNL. Electron emission coefficients reach *values of 130, whereas gas desorption coefficients are near 10{sup 4}. Mitigation techniques are being studied: A bead-blasted rough surface reduces electron emission by a factor of 10 and gas desorption by a factor of 2. Diagnostics are installed on HCX, between and within quadrupole magnets, to measure the beam halo loss, net charge and expelled ions, from which we infer gas density, electron trapping, and the effects of mitigation techniques. Here we discuss a new diagnostic technique that measures gas pressure and electron ionization rates within quadrupole magnets during the beam transit.

  2. Study of the neutron beam line shield design for JSNS.

    PubMed

    Kawai, M; Saito, K; Sanami, T; Nakao, N; Maekawa, F

    2005-01-01

    The JSNS, a spallation neutron source of J-PARC (JAERI-KEK Joint Project of the High Intensity Proton Accelerator) has 23 neutron beam lines. In the present study, a database was formulated for an optimum shielding design using the MCNP-X code. The calculations involved two steps. In the first step, the neutron distributions were created in the typical neutron beam line with a model that included the spallation neutron source target. The neutron currents evaluated flowed from the duct into the duct wall which was the boundary source for the bulk shield surrounding the beam line. In the second step, bulk-shield calculations were performed for the various shielding materials (iron, concrete, heavy concrete and so on) used and their composites up to thicknesses of 3 m. The results were compared with each other. Composite material shields of iron and such hydrogeneous materials as polyethylene or concrete were more effective. A typical design was prepared for a beam line within 25 m distance from a moderator, as a sample.

  3. Beam dynamics experiments to study the suppression of transverse instabilities

    NASA Astrophysics Data System (ADS)

    Houck, T.; Lidia, S.

    2003-03-01

    Two-beam accelerators based upon relativistic klystron’s (RK’s) have been proposed as power sources for future generation linear electron-positron colliders. These drivers are susceptible to several transverse beam breakup (BBU) instabilities. An experiment to study a particular technique (the “betatron node scheme”) for ameliorating the high-frequency BBU has been performed at LBNL on a 1MeV, 500A induction accelerator beam. The results of this experiment are particularly important for RK, but apply to any system where the betatron phase advance between perturbing structures is an integral multiple of 180°. This phase advance is beneficial in linear accelerators as the instability growth changes from exponential to linear. In the experiment described below, the beam is contained in a solenoidal focusing channel, rf cavities are spaced every 60cm, and growth in the transverse motion was measured as a function of phase advance. Details of the experiment and results are presented.

  4. Beam Loss Studies for the 2-MW LBNE Proton Beam Line

    SciTech Connect

    Drozhdin, A.I.; Childress, S.R.; Mokhov, N.V.; Tropin, I.S.; Zwaska, R.; /Fermilab

    2012-05-01

    Severe limits are put on allowable beam loss during extraction and transport of a 2.3 MW primary proton beam for the Long Baseline Neutrino Experiment (LBNE) at Fermilab. Detailed simulations with the STRUCT and MARS codes have evaluated the impact of beam loss of 1.6 x 10{sup 14} protons per pulse at 120 GeV, ranging from a single pulse full loss to sustained small fractional loss. It is shown that loss of a single beam pulse at 2.3 MW will result in a catastrophic event: beam pipe destruction, damaged magnets and very high levels of residual radiation inside and outside the tunnel. Acceptable beam loss limits have been determined and robust solutions developed to enable efficient proton beam operation under these constraints.

  5. Theoretical study of a cold-atom beam splitter

    SciTech Connect

    Gaaloul, Naceur; Suzor-Weiner, Annick; Charron, Eric; Pruvost, Laurence; Telmini, Mourad

    2006-08-15

    A theoretical model is presented for the study of the dynamics of a cold atomic cloud falling in the gravity field in the presence of two crossing dipole guides. The cloud is split between the two branches of this laser guide, and we compare experimental measurements of the splitting efficiency with semiclassical simulations. We then explore the possibilities of optimization of this beam splitter. Our numerical study also gives access to detailed information, such as the atom temperature after the splitting.

  6. Study on Flexural Behaviour of Ternary Blended Reinforced Self Compacting Concrete Beam with Conventional RCC Beam

    NASA Astrophysics Data System (ADS)

    Marshaline Seles, M.; Suryanarayanan, R.; Vivek, S. S.; Dhinakaran, G.

    2017-07-01

    The conventional concrete when used for structures having dense congested reinforcement, the problems such as external compaction and vibration needs special attention. In such case, the self compacting concrete (SCC) which has the properties like flow ability, passing and filling ability would be an obvious answer. All those SCC flow behavior was governed by EFNARC specifications. In present study, the combination type of SCC was prepared by replacing cement with silica fume (SF) and metakaolin (MK) along with optimum dosages of chemical admixtures. From the fresh property test, cube compressive strength and cylinder split tensile strength, optimum ternary mix was obtained. In order to study the flexural behavior, the optimum ternary mix was taken in which beam specimens of size 1200 mm x 100 mm x 200 mm was designed as singly reinforced section according to IS: 456-2000, Limit state method. Finally the comparative experimental analysis was made between conventional RCC and SCC beams of same grade in terms of flexural strength namely yield load & ultimate load, load- deflection curve, crack size and pattern respectively.

  7. Measurement of short lifetimes in highly-charged ions using a two-foil target

    SciTech Connect

    Berry, H.G.; Dunford, R.W.; Gemmell, D.S.

    1995-08-01

    One of the frontiers in the study of the atomic physics of highly-charged ions is the measurement of lifetimes in the 100 fs to 10 ps regime. The standard technique for measuring lifetimes of states in highly-charged ions is the beam-foil time-of-flight method in which the intensity of an emission line is monitored as a function of the separation between the exciting foil and the portion of the beam being viewed by the detector. This method becomes increasingly difficult as the decay lengths of the states of interest become shorter. At a typical beam velocity of 10% of the speed of light, the beam travels 30 microns in a picosecond. The standard beam-foil time-of-flight method necessitates observation of the decay radiation within one or two decay lengths from the foil while preventing the detectors from observing the beam spot at the foil. For short-lived states this requires tight collimation of the detector with a resulting loss in solid angle. We are developing a method for measuring ultrashort atomic lifetimes utilizing a two-foil target. As a specific case to demonstrate the feasibility of our method, we are studying the decay of the 2 {sup 3}P{sub 2} level in helium-like Kr{sup 34+}. This level has a calculated lifetime of 9.5 ps which corresponds to a decay length of 380 {mu}m. For krypton, theory predicts that 90% of the 2 {sup 3}P{sub 2} states decay via M2 radiation to the ground state. A measurement of the lifetime of this state would contribute to an important current problem which concerns the understanding of atomic structure when both electron correlations and relativistic effects are simultaneously important.

  8. Lifetime Performance Studies on Vacuum Photo-Triodes in the ECAL at CMS

    NASA Astrophysics Data System (ADS)

    Wood, John

    2011-10-01

    The electromagnetic calorimeter (ECAL) is a crucial sub-detector of the Compact Muon Solenoid (CMS) at the Large Hadron Collider (LHC). It uses scintillation light fr om approximately 83,000 Lead Tungstate (PbWO4) crystals to make precision measurements of high energy photons and electrons. In the endcaps of the ECAL this scinti llation light is collected at the rear of the crystal and converted to an analog electric current with radiation hard, single stage photmultipliers known as Vacuum Pho to-Triodes (VPTs). The response of the VPTs is dependent on several effects including orientation within the magnetic field, calibration and scintillation light expos ure rates, and time between successive exposures. The High Energy Physics group at the University of Virginia (UVa) uses a 3.8 T large-bore superconducting solenoid m agnet to simulate conditions at the LHC and to study the long term behavior of these VPTs under various light and magnetic field conditions. Also, using the ECAL lase r and LED calibration system, UVa is also able to study the response of the VPTs in situ at the CMS detector in order to understand and quantitatively assess the perfo rmance of the VPTs over time. Herein we will report on these remote and in-situ studies of VPT characteristics and performance.

  9. A study on the characteristics of the Analog Mean Delay (AMD) method for high-speed Fluorescence Lifetime Imaging Microscopy (FLIM)

    NASA Astrophysics Data System (ADS)

    Kim, Byungyeon; Park, Byungjun; Lee, Seungrag; Won, Youngjae

    2016-03-01

    We present a study on the characteristics of the AMD method. We have demonstrated that the photon economy of the AMD method is not degraded for longer lifetimes even when the applied integration window size is increased. By an extension of MCS, the photon economy with respect to different designs of the Gaussian low-pass filter (GLPF) used in the AMD setup was also studied. When a GLPF with the highest cutoff frequency of 100 MHz is applied, the most effective photon economy performance is achieved for lifetimes of 1, 3.2, 5, and 8 ns.

  10. Encountering abuse in health care; lifetime experiences in postnatal women - a qualitative study

    PubMed Central

    2013-01-01

    Background Abuse in health care (AHC) has been associated with potential severe health consequences, and has further been related to maternal morbidity and mortality in childbirth. To improve our understanding of what qualifies as AHC and to support and optimise the health of women with these experiences, the objective of this study was to describe how women, who had previously endured AHC, gave meaning to and managed their experience during pregnancy, childbirth, and in the early postnatal period. Method Women, who had reported substantial suffering as a result of a previous experience of abuse within the healthcare system, were purposefully selected from a Danish sample of a multinational cohort study on negative life events among pregnant women (the BIDENS Study). Eleven women were interviewed individually by means of a semi-structured interview guide. Transcripts of the interviews were analysed by means of qualitative systematic text condensation analysis. Results Four categories were identified to describe the women’s experience of AHC and its consequences on pregnancy and childbirth: abusive acts of unintentional harm, dehumanization, bodily remembrance, and finding the strength to move on. Abuse in health care may have profound consequences on the reproductive lives of the women, among others affecting sexuality, the desire to have children and the expectations of mode of delivery. However, the women described constructive ways to manage the experience, to which healthcare professionals could also contribute significantly. Conclusions Regardless of whether AHC is experienced in childhood or adulthood, it can influence the lives of women during pregnancy and childbirth. By recognising the potential existence of AHC, healthcare professionals have a unique opportunity to support women who have experienced AHC. PMID:23521853

  11. A Study on a Prognosis Algorithm for PEMFC Lifetime Prediction based on Durability Tests

    SciTech Connect

    Zhang, Xian; Pisu, Pierluigi; Toops, Todd J

    2010-01-01

    Of the fuel cells being studied, the proton exchange membrane fuel cell (PEMFC) is viewed as the most promising for transportation. Yet until today, the commercialization of the PEMFC has not been widespread in spite of its large expectation. Poor long term performances or durability, and high production and maintenance costs account for the main reasons. For the final commercialization of fuel cell in transportation field, the durability issue must be addressed, while the costs should be further brought down. In the meantime, health-monitoring and prognosis techniques are of great significance in ensuring the normal operation of the fuel cell and preventing or predicting its likely abrupt and catastrophic failure.

  12. Study on astrophysical reactions using low-energy RI beams

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hidetoshi

    2009-10-01

    In recent years, low-energy RI beams can be produced in a good intensity and they have been used for studying many astrophysical reactions. One of the facilities producing low-energy RI beams is CRIB (CNS Radio-Isotope Beam separator) [1,2], an RI-beam separator of Center for Nuclear Study, University of Tokyo. Taking CRIB as an example, recent improvements on the RI-beam production and experimental results on astrophysical studies are presented. Several experimental approaches have been taken for the studies on astrophysical reactions.The feature of each method are discussed based on real measurements performed at CRIB. One is the direct method, applied for measurements of reactions such as (α,p) [3]. Another is the measurement of proton/alpha resonance scattering using the thick target method in inverse kinematics, by which we can obtain information on the resonances relevant in astrophysical reactions [4,5]. A recent fruitful result was from a measurement of proton resonance scattering using a ^7Be beam [5]. The energy level structure of ^8B, revealed by the experiment, is especially of interest as it is related with the ^7Be(p,γ) ^8B reaction, responsible for the production of ^8B neutrinos in the sun. We successfully determined parameters of resonances in ^8B below 6.7 MeV, which may affect the ^7Be(p,γ)^8B reaction rate at the solar temparature. Indirect methods, such as ANC and the Trojan Horse Method, were also used in some of the measurements.[4pt] [1] S. Kubono et al., Eur. Phys. J. A13 (2002) 217.[0pt] [2] Y. Yanagisawa et al., Nucl. Instrum. Meth. Phys. Res., Sect. A 539 (2005) 74.[0pt] [3] M. Notani et al., Nucl. Phys. A 764 (2004) 113c.[0pt] [4] T. Teranishi et al., Phys. Lett. B 650 (2007) 129.[0pt] [5] H. Yamaguchi et al., Phys. Lett. B 672 (2009) 230.

  13. A fluorescence lifetime spectroscopy study of matrix metalloproteinases -2 and -9 in human atherosclerotic plaque

    PubMed Central

    Phipps, Jennifer E.; Hatami, Nisa; Galis, Zorina S.; Baker, J. Dennis; Fishbein, Michael C.; Marcu, Laura

    2011-01-01

    Matrix metalloproteinase (MMP) -2 and -9 play important roles in the progression of atherosclerosis. This study aims to determine whether MMP-2 and -9 content in the fibrotic caps of atherosclerotic plaque is correlated with plaque autofluorescence. A time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) system was used to measure the autofluorescence and assess the biochemical composition of human plaques obtained from carotid endarterectomy. Results presented here demonstrate for the first time the ability to characterize the biochemical composition as it relates to MMP-2 and -9 content in the atherosclerotic plaque cap using a label-free imaging technique implemented with a fiberoptic TR-LIFS system. PMID:21770037

  14. Measurement of the Neutron Lifetime by Counting Trapped Protons

    PubMed Central

    Wietfeldt, F. E.; Dewey, M. S.; Gilliam, D. M.; Nico, J. S.; Fei, X.; Snow, W. M.; Greene, G. L.; Pauwels, J.; Eykens, R.; Lamberty, A.; Van Gestel, J.

    2005-01-01

    We measured the neutron decay lifetime by counting in-beam neutron decay recoil protons trapped in a quasi-Penning trap. The absolute neutron beam fluence was measured by capture in a thin 6LiF foil detector with known efficiency. The combination of these measurements gives the neutron lifetime: τn = (886.8 ± 1.2 ± 3.2) s, where the first (second) uncertainty is statistical (systematic) in nature. This is the most precise neutron lifetime determination to date using an in-beam method. PMID:27308145

  15. Crossed-beam studies of the dynamics of radical reactions

    SciTech Connect

    Liu, K.

    1993-12-01

    The objective of this program is to characterize the detailed dynamics of elementary radical reactions and to provide a better understanding of radical reactivity in general. The radical beam is typically generated by a laser photolysis method. After colliding with the reacting molecule in a crossed-beam apparatus, the reaction product state distribution is interrogated by laser spectroscopic techniques. Several radicals of combustion significance, such as O, CH, OH, CN and NCO have been successfully generated and their collisional behavior at the state-to-state integral cross section level of detail has been studied in this manner. During the past year, the detection system has been converted from LIF to REMPI schemes, and the emphasis of this program shifted to investigate the product angular distributions. Both inelastic and reactive processes have been studied.

  16. On the Kinematics, Stability and Lifetime of Kinematically Distinct Cores: A Case Study

    NASA Astrophysics Data System (ADS)

    Schulze, Felix; Remus, Rhea-Silvia; Dolag, Klaus

    2017-08-01

    We present a case study of a early-type galaxy (ETG) hosting a kinematically distinct core (KDC) formed in a binary high resolution 1:1 spiral galaxy merger simulation. The runtime of the simulation is pushed up to 10Gyr to follow the complete evolution of various physical properties. To investigate the origin of the KDC, the stellar component residing within the KDC is dissected, revealing that the rotational signal is purely generated by stars that belong to the KDC for at least 0.5Gyr and are newly formed during the merging process. Following the orientation of the total stellar angular momentum of the KDC, we show that it performs a motion comparable to the precession of a gyroscope in a gravitational potential. We draw the conclusion that the motion of the KDC is a superposition of an intrinsic rotation and a global precession that gets gradually damped over cosmic time. Finally, the stability of the KDC over the complete runtime of the simulation is investigated by tracing the evolution of the widely used $\\lambda_{R}$ parameter and the misalignment angle distribution. We find that the KDC is stable for about 3Gyr after the merger and subsequently disperses completely on a timescale of ~1.5Gyr.

  17. Experimental Study on Creep Characterization and Lifetime Estimation of RPV Material at 723-1023 K

    NASA Astrophysics Data System (ADS)

    Xie, Lin-Jun; Ning, Dong; Yang, Yi-zhong

    2017-01-01

    During the plant operation, nuclear reactor pressure vessel (RPV) is the most critical pressure boundary component for integrity and safety in a light-water reactor. In this paper, the creep behavior and properties for RPV metallic material are studied by conducting constant-temperature and constant-load creep tests at 723, 823, 923 and 1023 K. The θ projection constitutive model was established based on a creep method to describe the high-temperature creep behavior of RPV material. The material parameter θ would be obtained based on experimental data by depending on numerical optimization techniques. The relationship between and among θ, T and σ was evaluated, and the coefficients a i , b i , c i and d i were obtained. Based on the short-term tests at a high temperature, the values for long-term creep data could be predicted in accordance with parameter θ. Moreover, rupture life, the minimum creep rate and the time reaching to an arbitrary strain can be calculated and may be used to evaluate the damage behavior and properties, so as to be used as a reference for design and safety assessment.

  18. Experimental Study on Creep Characterization and Lifetime Estimation of RPV Material at 723-1023 K

    NASA Astrophysics Data System (ADS)

    Xie, Lin-Jun; Ning, Dong; Yang, Yi-zhong

    2017-02-01

    During the plant operation, nuclear reactor pressure vessel (RPV) is the most critical pressure boundary component for integrity and safety in a light-water reactor. In this paper, the creep behavior and properties for RPV metallic material are studied by conducting constant-temperature and constant-load creep tests at 723, 823, 923 and 1023 K. The θ projection constitutive model was established based on a creep method to describe the high-temperature creep behavior of RPV material. The material parameter θ would be obtained based on experimental data by depending on numerical optimization techniques. The relationship between and among θ, T and σ was evaluated, and the coefficients a i , b i , c i and d i were obtained. Based on the short-term tests at a high temperature, the values for long-term creep data could be predicted in accordance with parameter θ. Moreover, rupture life, the minimum creep rate and the time reaching to an arbitrary strain can be calculated and may be used to evaluate the damage behavior and properties, so as to be used as a reference for design and safety assessment.

  19. Low-energy beam transport studies supporting the spallation neutron source 1-MW beam operationa)

    NASA Astrophysics Data System (ADS)

    Han, B. X.; Kalvas, T.; Tarvainen, O.; Welton, R. F.; Murray, S. N.; Pennisi, T. R.; Santana, M.; Stockli, M. P.

    2012-02-01

    The H- injector consisting of a cesium enhanced RF-driven ion source and a 2-lens electrostatic low-energy beam transport (LEBT) system supports the spallation neutron source 1 MW beam operation with ˜38 mA beam current in the linac at 60 Hz with a pulse length of up to ˜1.0 ms. In this work, two important issues associated with the low-energy beam transport are discussed: (1) inconsistent dependence of the post-radio frequency quadrupole accelerator beam current on the ion source tilt angle and (2) high power beam losses on the LEBT electrodes under some off-nominal conditions compromising their reliability.

  20. Genome-wide association study of lifetime cannabis use based on a large meta-analytic sample of 32 330 subjects from the International Cannabis Consortium.

    PubMed

    Stringer, S; Minică, C C; Verweij, K J H; Mbarek, H; Bernard, M; Derringer, J; van Eijk, K R; Isen, J D; Loukola, A; Maciejewski, D F; Mihailov, E; van der Most, P J; Sánchez-Mora, C; Roos, L; Sherva, R; Walters, R; Ware, J J; Abdellaoui, A; Bigdeli, T B; Branje, S J T; Brown, S A; Bruinenberg, M; Casas, M; Esko, T; Garcia-Martinez, I; Gordon, S D; Harris, J M; Hartman, C A; Henders, A K; Heath, A C; Hickie, I B; Hickman, M; Hopfer, C J; Hottenga, J J; Huizink, A C; Irons, D E; Kahn, R S; Korhonen, T; Kranzler, H R; Krauter, K; van Lier, P A C; Lubke, G H; Madden, P A F; Mägi, R; McGue, M K; Medland, S E; Meeus, W H J; Miller, M B; Montgomery, G W; Nivard, M G; Nolte, I M; Oldehinkel, A J; Pausova, Z; Qaiser, B; Quaye, L; Ramos-Quiroga, J A; Richarte, V; Rose, R J; Shin, J; Stallings, M C; Stiby, A I; Wall, T L; Wright, M J; Koot, H M; Paus, T; Hewitt, J K; Ribasés, M; Kaprio, J; Boks, M P; Snieder, H; Spector, T; Munafò, M R; Metspalu, A; Gelernter, J; Boomsma, D I; Iacono, W G; Martin, N G; Gillespie, N A; Derks, E M; Vink, J M

    2016-03-29

    Cannabis is the most widely produced and consumed illicit psychoactive substance worldwide. Occasional cannabis use can progress to frequent use, abuse and dependence with all known adverse physical, psychological and social consequences. Individual differences in cannabis initiation are heritable (40-48%). The International Cannabis Consortium was established with the aim to identify genetic risk variants of cannabis use. We conducted a meta-analysis of genome-wide association data of 13 cohorts (N=32 330) and four replication samples (N=5627). In addition, we performed a gene-based test of association, estimated single-nucleotide polymorphism (SNP)-based heritability and explored the genetic correlation between lifetime cannabis use and cigarette use using LD score regression. No individual SNPs reached genome-wide significance. Nonetheless, gene-based tests identified four genes significantly associated with lifetime cannabis use: NCAM1, CADM2, SCOC and KCNT2. Previous studies reported associations of NCAM1 with cigarette smoking and other substance use, and those of CADM2 with body mass index, processing speed and autism disorders, which are phenotypes previously reported to be associated with cannabis use. Furthermore, we showed that, combined across the genome, all common SNPs explained 13-20% (P<0.001) of the liability of lifetime cannabis use. Finally, there was a strong genetic correlation (rg=0.83; P=1.85 × 10(-8)) between lifetime cannabis use and lifetime cigarette smoking implying that the SNP effect sizes of the two traits are highly correlated. This is the largest meta-analysis of cannabis GWA studies to date, revealing important new insights into the genetic pathways of lifetime cannabis use. Future functional studies should explore the impact of the identified genes on the biological mechanisms of cannabis use.

  1. Genome-wide association study of lifetime cannabis use based on a large meta-analytic sample of 32 330 subjects from the International Cannabis Consortium

    PubMed Central

    Stringer, S; Minică, C C; Verweij, K J H; Mbarek, H; Bernard, M; Derringer, J; van Eijk, K R; Isen, J D; Loukola, A; Maciejewski, D F; Mihailov, E; van der Most, P J; Sánchez-Mora, C; Roos, L; Sherva, R; Walters, R; Ware, J J; Abdellaoui, A; Bigdeli, T B; Branje, S J T; Brown, S A; Bruinenberg, M; Casas, M; Esko, T; Garcia-Martinez, I; Gordon, S D; Harris, J M; Hartman, C A; Henders, A K; Heath, A C; Hickie, I B; Hickman, M; Hopfer, C J; Hottenga, J J; Huizink, A C; Irons, D E; Kahn, R S; Korhonen, T; Kranzler, H R; Krauter, K; van Lier, P A C; Lubke, G H; Madden, P A F; Mägi, R; McGue, M K; Medland, S E; Meeus, W H J; Miller, M B; Montgomery, G W; Nivard, M G; Nolte, I M; Oldehinkel, A J; Pausova, Z; Qaiser, B; Quaye, L; Ramos-Quiroga, J A; Richarte, V; Rose, R J; Shin, J; Stallings, M C; Stiby, A I; Wall, T L; Wright, M J; Koot, H M; Paus, T; Hewitt, J K; Ribasés, M; Kaprio, J; Boks, M P; Snieder, H; Spector, T; Munafò, M R; Metspalu, A; Gelernter, J; Boomsma, D I; Iacono, W G; Martin, N G; Gillespie, N A; Derks, E M; Vink, J M

    2016-01-01

    Cannabis is the most widely produced and consumed illicit psychoactive substance worldwide. Occasional cannabis use can progress to frequent use, abuse and dependence with all known adverse physical, psychological and social consequences. Individual differences in cannabis initiation are heritable (40–48%). The International Cannabis Consortium was established with the aim to identify genetic risk variants of cannabis use. We conducted a meta-analysis of genome-wide association data of 13 cohorts (N=32 330) and four replication samples (N=5627). In addition, we performed a gene-based test of association, estimated single-nucleotide polymorphism (SNP)-based heritability and explored the genetic correlation between lifetime cannabis use and cigarette use using LD score regression. No individual SNPs reached genome-wide significance. Nonetheless, gene-based tests identified four genes significantly associated with lifetime cannabis use: NCAM1, CADM2, SCOC and KCNT2. Previous studies reported associations of NCAM1 with cigarette smoking and other substance use, and those of CADM2 with body mass index, processing speed and autism disorders, which are phenotypes previously reported to be associated with cannabis use. Furthermore, we showed that, combined across the genome, all common SNPs explained 13–20% (P<0.001) of the liability of lifetime cannabis use. Finally, there was a strong genetic correlation (rg=0.83; P=1.85 × 10−8) between lifetime cannabis use and lifetime cigarette smoking implying that the SNP effect sizes of the two traits are highly correlated. This is the largest meta-analysis of cannabis GWA studies to date, revealing important new insights into the genetic pathways of lifetime cannabis use. Future functional studies should explore the impact of the identified genes on the biological mechanisms of cannabis use. PMID:27023175

  2. Use of exotic nuclear beams for nuclear structure studies

    SciTech Connect

    Sugimoto, K.

    1984-10-01

    Possible experiments are discussed for nuclear structure studies using, as secondary beams, projectile fragments produced by high-energy heavy-ion collisions. They are, specifically, (a) determination of nuclear sizes from measurements of the total interaction cross sections of nucleus-nucleus collisions, and (b) determination of static electromagnetic moments, ..mu..'s and Q's, of short-lived ..beta..-radioactive nuclei. 9 references.

  3. Electrostatic ion beam trap for electron collision studies

    SciTech Connect

    Heber, O.; Witte, P.D.; Diner, A.; Bhushan, K.G.; Strasser, D.; Toker, Y.; Rappaport, M.L.; Ben-Itzhak, I.; Altstein, N.; Schwalm, D.; Wolf, A.; Zajfman, D.

    2005-01-01

    We describe a system combining an ion beam trap and a low energy electron target in which the interaction between electrons and vibrationally cold molecular ions and clusters can be studied. The entire system uses only electrostatic fields for both trapping and focusing, thus being able to store particles without a mass limit. Preliminary results for the electron impact neutralization of C{sub 2}{sup -} ions and aluminum clusters are presented.

  4. Charge carrier transport and lifetimes in n-type and p-type phosphorene as 2D device active materials: an ab initio study.

    PubMed

    Tea, E; Hin, C

    2016-08-10

    In this work, we provide a detailed analysis of phosphorene's performance as an n-type and p-type active material. This study is based on first principles calculations of the phosphorene electronic structure, and the resulting electron and hole scattering rates and lifetimes. Emphasis is put on extreme regimes commonly found in semiconductor devices, i.e. high electric fields and heavy doping, where impact ionization and Auger recombination can occur. We found that electron-initiated impact ionization is weaker than the hole-initiated process, when compared to carrier-phonon interaction rates, suggesting resilience to impact ionization initiated breakdown. Moreover, calculated minority electron lifetimes are limited by radiative recombination only, not by Auger processes, suggesting that phosphorene could achieve good quantum efficiencies in optoelectronic devices. The provided scattering rates and lifetimes are critical input data for the modeling and understanding of phosphorene-based device physics.

  5. Beam Line Design and Beam Physics Study of Energy Recovery Linac Free Electron Laser at Peking University

    SciTech Connect

    Wang, Guimei

    2011-12-31

    Energy recovering linac (ERL) offers an attractive alternative for generating intense beams of charged particles by approaching the operational efficiency of a storage ring while maintaining the superior beam quality typical of a linear accelerator. In ERLs, the decelerated beam cancels the beam loading effects of the accelerated beam with high repetition rate. Therefore, ERLs can, in principle, accelerate very high average currents with only modest amounts of RF power. So the efficiency of RF power to beam is much higher. Furthermore, the energy of beam to dump is lower, so it will reduce dump radiation. With the successful experiments in large maximum-to-injection energy ratio up to 51:1 and high power FEL up to 14kW, the use of ERL, especially combining with superconducting RF technology, provides a potentially powerful new paradigm for generation of the charged particle beams used in MW FEL, synchrotron radiation sources, high-energy electron cooling devices and so on. The 3+1/2 DC-SC photo injector and two 9cell TESLA superconducting cavity for IR SASE FEL in PKU provides a good platform to achieve high average FEL with Energy Recovery. The work of this thesis is on Beam line design and Beam dynamics study of Energy Recovery Linac Free Electron Laser for Peking University. It is the upgrade of PKU facility, which is under construction. With ERL, this facility can work in CW mode, so it can operate high average beam current without RF power constraint in main linac and generate high average FEL power. Moreover, it provides a test facility to study the key technology in ERL. System parameters are optimized for PKU ERL-FEL. The oscillation FEL output power is studied with different bunch charge, transverse emittance, bunch length and energy spread. The theory of optimal RF power and Q{sub ext} with ERL and without ERL is analyzed and applied to PKU injector and linac including microphonic effect. pace charge effect in the injector and merger is studied for beam

  6. Recent Direct Reaction Experimental Studies with Radioactive Tin Beams

    DOE PAGES

    Jones, K. L.; Ahn, S.; Allmond, J. M.; ...

    2015-01-01

    Direct reaction techniques are powerful tools to study the single-particle nature of nuclei. Performing direct reactions on short-lived nuclei requires radioactive ion beams produced either via fragmentation or the Isotope Separation OnLine (ISOL) method. Some of the most interesting regions to study with direct reactions are close to the magic numbers where changes in shell structure can be tracked. These changes can impact the final abundances of explosive nucleosynthesis. The structure of the chain of tin isotopes is strongly influenced by the Z = 50 proton shell closure, as well as the neutron shell closures lying in the neutron-rich, Nmore » = 82, and neutron-deficient, N = 50, regions. Here, we present two examples of direct reactions on exotic tin isotopes. The first uses a one-neutron transfer reaction and a low-energy reaccelerated ISOL beam to study states in Sn-131 from across the N = 82 shell closure. The second example utilizes a one-neutron knockout reaction on fragmentation beams of neutron-deficient Sn-106,108Sn. In conclusion, In both cases, measurements of γ rays in coincidence with charged particles proved to be invaluable.« less

  7. Recent Direct Reaction Experimental Studies with Radioactive Tin Beams

    SciTech Connect

    Jones, K. L.; Ahn, S.; Allmond, J. M.; Ayres, A.; Bardayan, D. W.; Baugher, T.; Bazin, D.; Berryman, J. S.; Bey, A.; Bingham, C.; Cartegni, L.; Cerizza, G.; Chae, K. Y.; Cizewski, J. A.; Gade, A.; Galindo-Uribarri, A.; Garcia-Ruiz, R. F.; Grzywacz, R.; Howard, M. E.; Kozub, R. L.; Liang, J. F.; Manning, B.; Matoš, M.; McDaniel, S.; Miller, D.; Nesaraja, C. D.; O'Malley, P. D.; Padgett, S.; Padilla-Rodal, E.; Pain, S. D.; Pittman, S. T.; Radford, D. C.; Ratkiewicz, A.; Schmitt, K. T.; Shore, A.; Smith, M. S.; Stracener, D. W.; Stroberg, S. R.; Tostevin, J.; Varner, R. L.; Weisshaar, D.; Wimmer, K.; Winkler, R.

    2015-01-01

    Direct reaction techniques are powerful tools to study the single-particle nature of nuclei. Performing direct reactions on short-lived nuclei requires radioactive ion beams produced either via fragmentation or the Isotope Separation OnLine (ISOL) method. Some of the most interesting regions to study with direct reactions are close to the magic numbers where changes in shell structure can be tracked. These changes can impact the final abundances of explosive nucleosynthesis. The structure of the chain of tin isotopes is strongly influenced by the Z = 50 proton shell closure, as well as the neutron shell closures lying in the neutron-rich, N = 82, and neutron-deficient, N = 50, regions. Here, we present two examples of direct reactions on exotic tin isotopes. The first uses a one-neutron transfer reaction and a low-energy reaccelerated ISOL beam to study states in Sn-131 from across the N = 82 shell closure. The second example utilizes a one-neutron knockout reaction on fragmentation beams of neutron-deficient Sn-106,108Sn. In conclusion, In both cases, measurements of γ rays in coincidence with charged particles proved to be invaluable.

  8. Study of beam optics and beam halo by integrated modeling of negative ion beams from plasma meniscus formation to beam acceleration

    SciTech Connect

    Miyamoto, K.; Okuda, S.; Hatayama, A.; Hanada, M.; Kojima, A.

    2013-01-14

    To understand the physical mechanism of the beam halo formation in negative ion beams, a two-dimensional particle-in-cell code for simulating the trajectories of negative ions created via surface production has been developed. The simulation code reproduces a beam halo observed in an actual negative ion beam. The negative ions extracted from the periphery of the plasma meniscus (an electro-static lens in a source plasma) are over-focused in the extractor due to large curvature of the meniscus.

  9. Associations between Lifetime Traumatic Events and Subsequent Chronic Physical Conditions: A Cross-National, Cross-Sectional Study

    PubMed Central

    Scott, Kate M.; Koenen, Karestan C.; Aguilar-Gaxiola, Sergio; Alonso, Jordi; Angermeyer, Matthias C.; Benjet, Corina; Bruffaerts, Ronny; Caldas-de-Almeida, Jose Miguel; de Girolamo, Giovanni; Florescu, Silvia; Iwata, Noboru; Levinson, Daphna; Lim, Carmen C. W.; Murphy, Sam; Ormel, Johan; Posada-Villa, Jose; Kessler, Ronald C.

    2013-01-01

    Background Associations between lifetime traumatic event (LTE) exposures and subsequent physical ill-health are well established but it has remained unclear whether these are explained by PTSD or other mental disorders. This study examined this question and investigated whether associations varied by type and number of LTEs, across physical condition outcomes, or across countries. Methods Cross-sectional, face-to-face household surveys of adults (18+) were conducted in 14 countries (n = 38, 051). The Composite International Diagnostic Interview assessed lifetime LTEs and DSM-IV mental disorders. Chronic physical conditions were ascertained by self-report of physician's diagnosis and year of diagnosis or onset. Survival analyses estimated associations between the number and type of LTEs with the subsequent onset of 11 physical conditions, with and without adjustment for mental disorders. Findings A dose-response association was found between increasing number of LTEs and odds of any physical condition onset (OR 1.5 [95% CI: 1.4–1.5] for 1 LTE; 2.1 [2.0–2.3] for 5+ LTEs), independent of all mental disorders. Associations did not vary greatly by type of LTE (except for combat and other war experience), nor across countries. A history of 1 LTE was associated with 7/11 of the physical conditions (ORs 1.3 [1.2–1.5] to 1.7 [1.4–2.0]) and a history of 5+ LTEs was associated with 9/11 physical conditions (ORs 1.8 [1.3–2.4] to 3.6 [2.0–6.5]), the exceptions being cancer and stroke. Conclusions Traumatic events are associated with adverse downstream effects on physical health, independent of PTSD and other mental disorders. Although the associations are modest they have public health implications due to the high prevalence of traumatic events and the range of common physical conditions affected. The effects of traumatic stress are a concern for all medical professionals and researchers, not just mental health specialists. PMID:24348911

  10. Experimental Studying of Dust Particles Charging by Electron Beam

    SciTech Connect

    Gavrikov, A. V.; Fortov, V. E.; Petrov, O. F.; Vorona, N. A.; Vasiliev, M. N.

    2008-09-07

    The studying of the dusty plasma properties under electron beam action are of great interest because it gives the unique opportunities for experimental investigation of strongly coupled systems as well as for developing the new dusty plasma technologies of creating the new composite materials. Highly charged dust particle generates electrostatic field that can accelerate positive ions to high power. It gives the unique possibilities of using these macroparticles (for deeply ions implantation, as catalysts for increasing rate of reactions with the high energy barrier, in the new ionic engines etc.). Presented work deals with the experimental investigation of dust particles charging under direct influence of electron beam. On the basis of experimental data the average velocities of dust particles were obtained and the charge of macroparticle was estimated.

  11. Design study of longitudinal dynamics of the drive beam in 1 TeV relativistic klystron two-beam accelerator

    SciTech Connect

    Li, H.; Yu, S.S.; Sessler, A.M.

    1994-10-01

    In this paper the authors present a design study on the longitudinal dynamics of a relativistic klystron two-beam accelerator (RK-TBA) scheme which has been proposed as a power source candidate for a 1 TeV next linear collider (NLC). They address the issue of maintaining stable power output at desired level for a 300-m long TBA with 150 extraction cavities and present their simulation results to demonstrate that it can be achieved by inductively detuning the extraction cavities to counter the space charge debunching effect on the drive beam. They then carry out simulation study to show that the beam bunches desired by the RK-TBA can be efficiently obtained by first chopping an initially uniform beam of low energy into a train of beam bunches with modest longitudinal dimension and then using the {open_quotes}adiabatic capture{close_quotes} scheme to bunch and accelerate these beam bunches into tight bunches at the operating energy of the drive beam. The authors have also examined the {open_quotes}after burner{close_quotes} scheme which is implemented in their RK-TBA design for efficiency enhancement.

  12. A Study of Effects of Tissue Inhomogeneity on HIFU Beam

    NASA Astrophysics Data System (ADS)

    Amin, Viren; Roberts, Ron; Long, Tao; Thompson, R. B.; Ryken, Timothy

    2006-05-01

    The potential of high-intensity focused ultrasound (HIFU) will not be realized unless the effects of overlaying tissues are understood in such a way that allows for estimation of HIFU dose distribution at a target tissue. We employ computational models to examine the impact of phase aberration on tissue ablation. Thompson and Roberts have recently studied the effects of phase aberration on ultrasound focusing in aerospace engine materials such as titanium alloy, and have developed a computational model to examine these effects. The ultrasound beam observed after transmission through the fused quartz (homogeneous) and that observed after transmission through the titanium (inhomogeneous) demonstrate the severe beam wavefield amplitude distortion introduced by the velocity inhomogeneity-induced phase aberration. We study applicability of this approach to model phase aberration in inhomogeneous tissues and its effect on HIFU dose distribution around the focus. It is hypothesized that the ill-effects of phase aberration accumulate during propagation through intervening tissue in which field intensities are substantially lower than that in the focal zone, and it is therefore appropriate to use a linear acoustic model to describe the transport of energy from the transducer to the volume targeted for ablation. We present initial results of the simulation and experiments of beam measurements under water without and with different tissue layers.

  13. Why do general circulation models overestimate the aerosol cloud lifetime effect? A case study comparing CAM5 and a CRM

    NASA Astrophysics Data System (ADS)

    Zhou, Cheng; Penner, Joyce E.

    2017-01-01

    Observation-based studies have shown that the aerosol cloud lifetime effect or the increase of cloud liquid water path (LWP) with increased aerosol loading may have been overestimated in climate models. Here, we simulate shallow warm clouds on 27 May 2011 at the southern Great Plains (SGP) measurement site established by the Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program using a single-column version of a global climate model (Community Atmosphere Model or CAM) and a cloud resolving model (CRM). The LWP simulated by CAM increases substantially with aerosol loading while that in the CRM does not. The increase of LWP in CAM is caused by a large decrease of the autoconversion rate when cloud droplet number increases. In the CRM, the autoconversion rate is also reduced, but this is offset or even outweighed by the increased evaporation of cloud droplets near the cloud top, resulting in an overall decrease in LWP. Our results suggest that climate models need to include the dependence of cloud top growth and the evaporation/condensation process on cloud droplet number concentrations.

  14. Vibrational lifetimes of hydrogen on lead films: An ab initio molecular dynamics with electronic friction (AIMDEF) study

    SciTech Connect

    Saalfrank, Peter; Juaristi, J. I.

    2014-12-21

    Using density functional theory and Ab Initio Molecular Dynamics with Electronic Friction (AIMDEF), we study the adsorption and dissipative vibrational dynamics of hydrogen atoms chemisorbed on free-standing lead films of increasing thickness. Lead films are known for their oscillatory behaviour of certain properties with increasing thickness, e.g., energy and electron spillout change in discontinuous manner, due to quantum size effects [G. Materzanini, P. Saalfrank, and P. J. D. Lindan, Phys. Rev. B 63, 235405 (2001)]. Here, we demonstrate that oscillatory features arise also for hydrogen when chemisorbed on lead films. Besides stationary properties of the adsorbate, we concentrate on finite vibrational lifetimes of H-surface vibrations. As shown by AIMDEF, the damping via vibration-electron hole pair coupling dominates clearly over the vibration-phonon channel, in particular for high-frequency modes. Vibrational relaxation times are a characteristic function of layer thickness due to the oscillating behaviour of the embedding surface electronic density. Implications derived from AIMDEF for frictional many-atom dynamics, and physisorbed species will also be given.

  15. Lifetime hypertension as a predictor of brain structure in older adults: cohort study with a 28-year follow-up.

    PubMed

    Allan, Charlotte L; Zsoldos, Enikõ; Filippini, Nicola; Sexton, Claire E; Topiwala, Anya; Valkanova, Vyara; Singh-Manoux, Archana; Tabák, Adam G; Shipley, Martin J; Mackay, Clare; Ebmeier, Klaus P; Kivimäki, Mika

    2015-04-01

    Hypertension is associated with an increased risk of dementia and depression with uncertain longitudinal associations with brain structure. To examine lifetime blood pressure as a predictor of brain structure in old age. A total of 190 participants (mean age 69.3 years) from the Whitehall II study were screened for hypertension six times (1985-2013). In 2012-2013, participants had a 3T-magnetic resonance imaging (MRI) brain scan. Data from the MRI were analysed using automated and visual measures of global atrophy, hippocampal atrophy and white matter hyperintensities. Longitudinally, higher mean arterial pressure predicted increased automated white matter hyperintensities (P<0.002). Cross-sectionally, hypertensive participants had increased automated white matter hyperintensities and visually rated deep white matter hyperintensities. There was no significant association with global or hippocampal atrophy. Long-term exposure to high blood pressure predicts hyperintensities, particularly in deep white matter. The greatest changes are seen in those with severe forms of hypertension, suggesting a dose-response pattern. Royal College of Psychiatrists.

  16. Lifetime criminality among boys with ADHD: a prospective follow-up study into adulthood using official arrest records

    PubMed Central

    Mannuzza, Salvatore; Klein, Rachel G.; Moulton, John L.

    2008-01-01

    This study investigates the relationship between childhood attention deficit hyperactivity disorder (ADHD) and later criminality. White boys (n = 207, ages 6–12) with ADHD, free of conduct disorder, were assessed at ages 18 and 25 by clinicians who were blind to childhood status. A non-ADHD group served as comparisons. Lifetime arrest records were obtained when subjects were 38 years old for subjects who resided in New York State throughout the follow-up interval (93 probands, 93 comparisons). Significantly more ADHD probands than comparisons had been arrested (47% vs. 24%), convicted (42% vs. 14%), and incarcerated (15% vs. 1%). Rates of felonies and aggressive offenses also were significantly higher among probands. Importantly, the development of an antisocial or substance use disorder in adolescence completely explained the increased risk for subsequent criminality. Results suggest that even in the absence of comorbid conduct disorder in childhood, ADHD increases the risk for developing antisocial and substance use disorders in adolescence, which, in turn, increases the risk for criminal behavior in adolescence and adulthood. PMID:18707766

  17. In vivo detection of oral epithelial cancer using endogenous fluorescence lifetime imaging: a pilot human study (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Jo, Javier A.; Hwang, Dae Yon; Palma, Jorge; Cheng, Shuna; Cuenca, Rodrigo; Malik, Bilal; Jabbour, Joey; Cheng, Lisa; Wright, John; Maitland, Kristen

    2016-03-01

    Endogenous fluorescence lifetime imaging (FLIM) provides direct access to the concomitant functional and biochemical changes accompanying tissue transition from benign to precancerous and cancerous. Since FLIM can noninvasively measure different and complementary biomarkers of precancer and cancer, we hypothesize that it will aid in clinically detecting early oral epithelial cancer. Our group has recently demonstrated the detection of benign from premalignant and malignant lesions based on endogenous multispectral FLIM in the hamster cheek-pouch model. Encouraged by these positive preliminary results, we have developed a handheld endoscope capable of acquiring multispectral FLIM images in real time from the oral mucosa. This novel FLIM endoscope is being used for imaging clinically suspicious pre-malignant and malignant lesions from patients before undergoing tissue biopsy for histopathological diagnosis of oral epithelial cancer. Our preliminary results thus far are already suggesting the potential of endogenous FLIM for distinguishing a variety of benign lesions from advanced dysplasia and squamous cell carcinoma (SCC). To the best of out knowledge, this is the first in vivo human study aiming to demonstrate the ability to predict the true malignancy of clinically suspicious lesions using endogenous FLIM. If successful, the resulting clinical tool will allow noninvasive real-time detection of epithelial precancerous and cancerous lesions in the oral mucosa and could potentially be used to assist at every step involved on the clinical management of oral cancer patients, from early screening and diagnosis, to treatment and monitoring of recurrence.

  18. Why do general circulation models overestimate the aerosol cloud lifetime effect? A case study comparing CAM5 and a CRM

    DOE PAGES

    Zhou, Cheng; Penner, Joyce E.

    2017-01-02

    Observation-based studies have shown that the aerosol cloud lifetime effect or the increase of cloud liquid water path (LWP) with increased aerosol loading may have been overestimated in climate models. Here, we simulate shallow warm clouds on 27 May 2011 at the southern Great Plains (SGP) measurement site established by the Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program using a single-column version of a global climate model (Community Atmosphere Model or CAM) and a cloud resolving model (CRM). The LWP simulated by CAM increases substantially with aerosol loading while that in the CRM does not. The increase of LWP inmore » CAM is caused by a large decrease of the autoconversion rate when cloud droplet number increases. In the CRM, the autoconversion rate is also reduced, but this is offset or even outweighed by the increased evaporation of cloud droplets near the cloud top, resulting in an overall decrease in LWP. Our results suggest that climate models need to include the dependence of cloud top growth and the evaporation/condensation process on cloud droplet number concentrations.« less

  19. Potential energy curves and lifetimes of low-lying excited electronic states of CSe studied by configuration interaction method.

    PubMed

    Li, Rui; Sun, Erping; Jin, Mingxing; Xu, Haifeng; Yan, Bing

    2014-04-10

    In this work, we performed a high level ab initio study on the low-lying electronic states of CSe, utilizing MRCI+Q (the internally contracted multireference configuration interaction, and Davidson's correction) method with scalar relativistic and spin-orbit coupling effects taken into account. The potential energy curves of 18 Λ-S states associated with the lowest dissociation limit of CSe molecule, as well as those of 50 Ω states generated from the Λ-S states were computed. The spectroscopic parameters of bound states were evaluated, which agree well with existing theoretical and experimental results. With the aid of calculated spin-orbit matrix elements and the Λ-S compositional variation of the Ω states, the spin-orbit perturbations of low-lying states to the A(1)Π and a(3)Π states are analyzed. Finally, the transition dipole moments of A(1)Π, A'(1)Σ(+), a(3)Π0+, and a(3)Π1 to the ground X(1)Σ(+) state as well as the lifetimes of the four excited states were evaluated.

  20. The association of pattern of lifetime alcohol use and cause of death in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

    PubMed Central

    Bergmann, Manuela M; Rehm, Jürgen; Klipstein-Grobusch, Kerstin; Boeing, Heiner; Schütze, Madlen; Drogan, Dagmar; Overvad, Kim; Tjønneland, Anne; Halkjær, Jytte; Fagherazzi, Guy; Boutron-Ruault, Marie-Christine; Clavel-Chapelon, Françoise; Teucher, Birgit; Kaaks, Rudolph; Trichopoulou, Antonia; Benetou, Vassiliki; Trichopoulos, Dimitrios; Palli, Domenico; Pala, Valeria; Tumino, Rosario; Vineis, Paolo; Beulens, Joline WJ; Redondo, Maria Luisa; Duell, Eric J; Molina-Montes, Esther; Navarro, Carmen; Barricarte, Aurelio; Arriola, Larraitz; Allen, Naomi E; Crowe, Francesca L; Khaw, Kay-Tee; Wareham, Nick; Romaguera, Dora; Wark, Petra A; Romieu, Isabelle; Nunes, Luciana; Riboli, Elio; Ferrari, Pietro

    2013-01-01

    Background There is limited evidence for an association between the pattern of lifetime alcohol use and cause-specific risk of death. Methods Multivariable hazard ratios were estimated for different causes of death according to patterns of lifetime alcohol consumption using a competing risks approach: 111 953 men and 268 442 women from eight countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC) study were included. Self-reported alcohol consumption at ages 20, 30, 40 or 50 years and at enrolment were used for the analysis; 26 411 deaths were observed during an average of 12.6 years of follow-up. Results The association between lifetime alcohol use and death from cardiovascular diseases was different from the association seen for alcohol-related cancers, digestive, respiratory, external and other causes. Heavy users (>5 drinks/day for men and >2.5 drinks/day for women), regardless of time of cessation, had a 2- to 5-times higher risk of dying due to alcohol-related cancers, compared with subjects with lifetime light use (≤1 and ≤0.5 drink/week for men and women, respectively). Compared with lifetime light users, men who used <5 drinks/day throughout their lifetime had a 24% lower cardiovascular disease mortality (95% confidence interval 2-41). The risk of death from coronary heart disease was also found to be 34–46% lower among women who were moderate to occasionally heavy alcohol users compared with light users. However, this relationship was only evident among men and women who had no chronic disease at enrolment. Conclusions Limiting alcohol use throughout life is associated with a lower risk of death, largely due to cardiovascular disease but also other causes. However, the potential health benefits of alcohol use are difficult to establish due to the possibility of selection bias and competing risks related to diseases occurring later in life. PMID:24415611

  1. Psychosocial aetiology of chronic disease: a pragmatic approach to the assessment of lifetime affective morbidity in an EPIC component study

    PubMed Central

    Surtees, P; Wainwright, N; Brayne, C

    2000-01-01

    OBJECTIVES—The Health and Life Experiences Questionnaire (HLEQ) was developed for use in a prospective cohort study of 25 000 men and women living in Norfolk and forms a component study of the European Prospective Investigation into Cancer and Nutrition (EPIC). The HLEQ includes an assessment of mood status over the life course allowing a limited capacity for the imposition of diagnostic criteria to enable eventual evaluation of mental health status for chronic disease outcomes. This paper reports estimates of HLEQ Major Depressive Disorder (MDD) prevalence and compares them with those obtained through interviewer-based methods. In addition evidence for the impact of recall, clustering or cohort effects on these estimates are examined.
PARTICIPANTS—3491 eligible respondents to EPIC in Norfolk, aged 45-74 years, recruited from the first five general practices who completed the HLEQ.
MAIN RESULTS—MDD prevalence estimates were found to be closely comparable to those obtained recently (by interview) in the UK and to those lifetime MDD rates determined through international studies. Risk of MDD onset was found to vary with age as expected from earlier studies using interviewer-based assessments. Limited evidence was found to show that the distribution of first onset MDD episodes were compressed during the immediate pre-assessment period. Results were also consistent with previous evidence demonstrating the raised risk of MDD among women and of the decline in gender differences with advancing age.
CONCLUSIONS—These results suggest that estimates of putative MDD diagnostic status, derived through the HLEQ, and of associated demographic risk are similar to those derived by more intensive and costly assessment methods. Implications for the future study of MDD both as an outcome and as a risk factor for chronic disease are discussed.


Keywords: depression; epidemiology; prevalence PMID:10715744

  2. Carrier lifetimes and interface recombination velocities in CdTe/Mg{sub x}Cd{sub 1−x}Te double heterostructures with different Mg compositions grown by molecular beam epitaxy

    SciTech Connect

    Liu, Shi; Lassise, Maxwell B.; Zhao, Yuan; Zhang, Yong-Hang; Zhao, Xin-Hao; Campbell, Calli M.

    2015-07-27

    The interface recombination velocities of CdTe/Mg{sub x}Cd{sub 1−x}Te double heterostructure (DH) samples with different CdTe layer thicknesses and Mg compositions are studied using time-resolved photoluminescence measurements. A lowest interface recombination velocity of 30 ± 10 cm/s has been measured for the CdTe/Mg{sub 0.46}Cd{sub 0.54}Te interface, and a longest carrier lifetime of 0.83 μs has been observed for the studied DHs. These values are very close to the best reported numbers for GaAs/AlGaAs DHs. The impact of carrier escape through thermionic emission over the MgCdTe barrier on the recombination process in the DHs is also studied.

  3. Neutralized ion beam modification of cellulose membranes for study of ion charge effect on ion-beam-induced DNA transfer

    NASA Astrophysics Data System (ADS)

    Prakrajang, K.; Sangwijit, K.; Anuntalabhochai, S.; Wanichapichart, P.; Yu, L. D.

    2012-02-01

    Low-energy ion beam biotechnology (IBBT) has recently been rapidly developed worldwide. Ion-beam-induced DNA transfer is one of the important applications of IBBT. However, mechanisms involved in this application are not yet well understood. In this study plasma-neutralized ion beam was applied to investigate ion charge effect on induction of DNA transfer. Argon ion beam at 7.5 keV was neutralized by RF-driven plasma in the beam path and then bombarded cellulose membranes which were used as the mimetic plant cell envelope. Electrical properties such as impedance and capacitance of the membranes were measured after the bombardment. An in vitro experiment on plasmid DNA transfer through the cellulose membrane was followed up. The results showed that the ion charge input played an important role in the impedance and capacitance changes which would affect DNA transfer. Generally speaking, neutral particle beam bombardment of biologic cells was more effective in inducing DNA transfer than charged ion beam bombardment.

  4. Radiobiological study by using laser-driven proton beams

    NASA Astrophysics Data System (ADS)

    Yogo, A.; Sato, K.; Nishikino, M.; Mori, M.; Teshima, T.; Numasaki, H.; Murakami, M.; Demizu, Y.; Akagi, S.; Nagayama, S.; Ogura, K.; Sagisaka, A.; Orimo, S.; Nishiuchi, M.; Pirozhkov, A. S.; Ikegami, M.; Tampo, M.; Sakaki, H.; Suzuki, M.; Daito, I.; Oishi, Y.; Sugiyama, H.; Kiriyama, H.; Okada, H.; Kanazawa, S.; Kondo, S.; Shimomura, T.; Nakai, Y.; Tanoue, M.; Sugiyama, H.; Sasao, H.; Wakai, D.; Kawachi, T.; Nishimura, H.; Bolton, P. R.; Daido, H.

    2009-07-01

    Particle acceleration driven by high-intensity laser systems is widely attracting interest as a potential alternative to conventional ion acceleration, including ion accelerator applications to tumor therapy. Recent works have shown that a high intensity laser pulse can produce single proton bunches of a high current and a short pulse duration. This unique feature of laser-ion acceleration can lead to progress in the development of novel ion sources. However, there has been no experimental study of the biological effects of laser-driven ion beams. We describe in this report the first demonstrated irradiation effect of laser-accelerated protons on human lung cancer cells. In-vitro A549 cells are irradiated with a proton dose of 20 Gy, resulting in a distinct formation of γ-H2AX foci as an indicator of DNA double-strand breaks. This is a pioneering result that points to future investigations of the radiobiological effects of laser-driven ion beams. The laser-driven ion beam is apotential excitation source for time-resolved determination of hydroxyl (OH) radical yield, which will explore relationship between the fundamental chemical reactions of radiation effects and consequent biological processes.

  5. SPS ionosphere/microwave beam interactions: Arecibo experimental studies

    SciTech Connect

    Duncan, L.M.

    1980-10-01

    The purpose of this program is to determine the environmental impacts associated with the operation of the proposed SPS microwave power transmission system. It is expected that thermal effects will provide the dominant force driving the nonlinear ionosphere/microwave beam interactions. Collisional damping of radio waves, producing ohmic heating of the ionospheric plasma, depends inversely on the square of the radio wave frequency. Therefore, equivalent heating and equivalent thermal forces can be generated at lower radiated power densities by using lower radio wave frequencies. This principle is fundamental to a large part of the experimental program. An understanding of the physics of the specific interactions excited by the SPS microwave beam is also an important part of the assessment program. This program is designed to determine instability thresholds, the growth rates and spatial extent of the resultant ionospheric disturbances, and the frequency and power dependences of the interactions. How these interactions are affected by variations in the natural ionospheric conditions, how different instabilities occurring simultaneously may affect each other, and how distinct microwave beams might mutually interact are studied. Status of the program is described. (WHK)

  6. Radiobiological study by using laser-driven proton beams

    SciTech Connect

    Yogo, A.; Nishikino, M.; Mori, M.; Ogura, K.; Sagisaka, A.; Orimo, S.; Nishiuchi, M.; Pirozhkov, A. S.; Ikegami, M.; Tampo, M.; Sakaki, H.; Suzuki, M.; Daito, I.; Kiriyama, H.; Okada, H.; Kanazawa, S.; Kondo, S.; Shimomura, T.; Nakai, Y.; Kawachi, T.

    2009-07-25

    Particle acceleration driven by high-intensity laser systems is widely attracting interest as a potential alternative to conventional ion acceleration, including ion accelerator applications to tumor therapy. Recent works have shown that a high intensity laser pulse can produce single proton bunches of a high current and a short pulse duration. This unique feature of laser-ion acceleration can lead to progress in the development of novel ion sources. However, there has been no experimental study of the biological effects of laser-driven ion beams. We describe in this report the first demonstrated irradiation effect of laser-accelerated protons on human lung cancer cells. In-vitro A549 cells are irradiated with a proton dose of 20 Gy, resulting in a distinct formation of gamma-H2AX foci as an indicator of DNA double-strand breaks. This is a pioneering result that points to future investigations of the radiobiological effects of laser-driven ion beams. The laser-driven ion beam is apotential excitation source for time-resolved determination of hydroxyl (OH) radical yield, which will explore relationship between the fundamental chemical reactions of radiation effects and consequent biological processes.

  7. Low energy crossed beam studies of OD+ and D2O+ with C2H4: covalent and electrostatic complexes

    NASA Astrophysics Data System (ADS)

    Liu, Li; Li, Yue; Cai, Xiaohui; Richards, Elizabeth S.; Farrar, James M.

    2007-09-01

    Density functional theory (DFT) calculations are used in conjunction with low-energy crossed beam studies of the ion-molecule reactions of D2O+ and OD+ with C2H4 to probe collision dynamics, particularly the role that electrostatic and covalent intermediates play. In the D+-transfer reaction initiated with D2O+, an electrostatic complex formed when the transferred species approaches the perpendicular bisector of the C=C bond plays an important role. Observation of C2H4D+ products with excitation in the ν10 stretching mode, in which the bridging D-atom moves along the perpendicular bisector, provides support for this complex. In the OD+ reaction, evidence for the occurrence of reaction on the ground singlet surface following internal conversion comes from the observation of a transient complex living ~100 fs. The DFT calculations show that the rate-limiting step corresponds to ring-opening and H/D exchange initiated in an ethylene oxide species with D+ bound to the oxygen atom. Computed lifetimes are in agreement with experiment. This study provides an example of how high-resolution crossed beam studies in conjunction with quantum chemical calculations, can provide a detailed understanding of collision dynamics in systems of moderate complexity. New experimental developments, including the application of velocity space imaging methods, as well as the production of beams of free radicals, will lead to a greater understanding of energy and angular momentum disposal in systems of chemical relevance.

  8. A neutronic feasibility study for LEU conversion of the high flux beam reactor (HFBR).

    SciTech Connect

    Pond, R. B.

    1998-01-16

    A neutronic feasibility study for converting the High Flux Beam Reactor at Brookhaven National Laboratory from HEU to LEU fuel was performed at Argonne National Laboratory. The purpose of this study is to determine what LEU fuel density would be needed to provide fuel lifetime and neutron flux performance similar to the current HEU fuel. The results indicate that it is not possible to convert the HFBR to LEU fuel with the current reactor core configuration. To use LEU fuel, either the core needs to be reconfigured to increase the neutron thermalization or a new LEU reactor design needs to be considered. This paper presents results of reactor calculations for a reference 28-assembly HEU-fuel core configuration and for an alternative 18-assembly LEU-fuel core configuration with increased neutron thermalization. Neutronic studies show that similar in-core and ex-core neutron fluxes, and fuel cycle length can be achieved using high-density LEU fuel with about 6.1 gU/cm{sup 3} in an altered reactor core configuration. However, hydraulic and safety analyses of the altered HFBR core configuration needs to be performed in order to establish the feasibility of this concept.

  9. Radioactive-ion-beam research at Livermore

    NASA Astrophysics Data System (ADS)

    Haight, R. C.; Mathews, G. J.; Ward, R. A.; Woosley, S. E.

    1983-06-01

    The ability to produce secondary radioactive heavy ion beams which can be isolated, focused, and transported to a secondary target can enable reaction studies and other research with the approximately more than 1300 nuclei with decay lifetimes approximately more than 1 microsec. Current research in secondary beam production and future applications in astrophysics, nuclear structure, heavy ion physics, and radiotherapy are examined as well as associated spin off and technology transfer in applied physics.

  10. Effect of Superalloy Substrate and Bond Coating on TBC Lifetime

    SciTech Connect

    Pint, Bruce A; Haynes, James A; Zhang, Ying

    2010-01-01

    Several different single-crystal superalloys were coated with different bond coatings to study the effect of composition on the cyclic oxidation lifetime of an yttria-stabilized zirconia (YSZ) top coating deposited by electron beam physical vapor deposition from a commercial source. Three different superalloys were coated with a 7 {micro}m Pt layer that was diffused into the surface prior to YSZ deposition. One of the superalloys, N5, was coated with a low activity, Pt-modified aluminide coating and Pt-diffusion coatings with 3 and 7 {micro}m of Pt. Three coatings of each type were furnace cycled to failure in 1 h cycles at 1150 C to assess average coating lifetime. The 7 {micro}m Pt diffusion coating on N5 had an average YSZ coating lifetime >50% higher than a Pt-modified aluminide coating on N5. Without a YSZ coating, the Pt-modified aluminide coating on N5 showed the typical surface deformation during cycling, however, the deformation was greatly reduced when constrained by the YSZ coating. The 3 {micro}m Pt diffusion coating had a similar average lifetime as the Pt-modified aluminide coating but a much wider scatter. The Pt diffusion bond coating on superalloy X4 containing Ti exhibited the shortest YSZ coating lifetime, this alloy-coating combination also showed the worst alumina scale adhesion without a YSZ coating. The third generation superalloy N6 exhibited the longest coating lifetime with a 7 {micro}m Pt diffusion coating.

  11. Beam Impedance Study for the BESSY-II Storage Ring

    NASA Astrophysics Data System (ADS)

    Khan, S.

    1997-05-01

    The beam impedance of the BESSY-II storage ring was studied using analytical estimates, simulating wake fields with the computer code MAFIA, and measuring the impedance of several vacuum chamber elements. The main contribution to the impedance comes from the cavity HOMs. The broadband impedance from other discontinuities of the vacuum chamber was minimized as far as possible, and the impedance due to the wall resistivity was taken into account. The results of this study are presented together with estimates for single- and coupled-bunch instabilities.

  12. Beam-Beam Interactions

    SciTech Connect

    Sramek, Christopher

    2003-09-05

    At the interaction point of a particle accelerator, various phenomena occur which are known as beam-beam effects. Incident bunches of electrons (or positrons) experience strong electromagnetic fields from the opposing bunches, which leads to electron deflection, beamstrahlung and the creation of electron/positron pairs and hadrons due to two-photon exchange. In addition, the beams experience a ''pinch effect'' which focuses each beam and results in either a reduction or expansion of their vertical size. Finally, if a beam's disruption parameter is too large, the beam can develop a sinusoidal distortion, or two-stream (kink) instability. This project simulated and studied these effects as they relate to luminosity, deflection angles and energy loss in order to optimize beam parameters for the Next Linear Collider (NLC). Using the simulation program Guinea-Pig, luminosity, deflection angle and beam energy data was acquired for different levels of beam offset and distortion. Standard deflection curves and luminosity plots agreed with theoretical models but also made clear the difficulties of e-e- feedback. Simulations emphasizing kink instability in modulated and straight beam collisions followed qualitative behavioral predictions and roughly fit recent analytic calculations. Finally, a study of e-e- collisions under design constraints for the NLC provided new estimates of how luminosity, beamstrahlung energy loss, upsilon parameter and deflection curve width scale with beam spotsizes.

  13. Increasing precision of lifetime determination in fluorescence lifetime imaging

    NASA Astrophysics Data System (ADS)

    Chang, Ching-Wei; Mycek, Mary-Ann

    2010-02-01

    The interest in fluorescence lifetime imaging microscopy (FLIM) is increasing, as commercial FLIM modules become available for confocal and multi-photon microscopy. In biological FLIM applications, low fluorescence signals from samples can be a challenge, and this causes poor precision in lifetime. In this study, for the first time, we applied wavelet-based denoising methods in time-domain FLIM, and compared them with our previously developed total variation (TV) denoising methods. They were first tested using artificial FLIM images. We then applied them to lowlight live-cell images. The results demonstrated that our TV methods could improve lifetime precision multi-fold in FLIM images and preserve the overall lifetime and pre-exponential term values when improving local lifetime fitting, while wavelet-based methods were faster. The results here can enhance the precision of FLIM, especially for low-light and / or fast video-rate imaging, to improve current and rapidly emerging new applications of FLIM such as live-cell, in vivo whole-animal, or endoscopic imaging.

  14. Design study of low-energy beam transport for multi-charge beams at RAON

    NASA Astrophysics Data System (ADS)

    Bahng, Jungbae; Qiang, Ji; Kim, Eun-San

    2015-12-01

    The Rare isotope Accelerator Of Newness (RAON) at the Rare Isotope Science Project (RISP) is being designed to simultaneously accelerate beams with multiple charge states. It includes a driver superconducting (SC) linac for producing 200 MeV/u and 400 kW continuous wave (CW) heavy ion beams from protons to uranium. The RAON consists of a few electron cyclotron resonance ion sources, a low-energy beam transport (LEBT) system, a CW 81.25 MHz, 500 keV/u radio frequency quadrupole (RFQ) accelerator, a medium-energy beam transport system, the SC linac, and a charge-stripper system. The LEBT system for the RISP accelerator facility consists of a high-voltage platform, two 90° dipoles, a multi-harmonic buncher (MHB), solenoids, electrostatic quadrupoles, a velocity equalizer, and a diagnostic system. The ECR ion sources are located on a high-voltage platform to reach an initial beam energy of 10 keV/u. After extraction, the ion beam is transported through the LEBT system to the RFQ accelerator. The generated charge states are selected by an achromatic bending system and then bunched by the MHB in the LEBT system. The MHB is used to achieve a small longitudinal emittance in the RFQ by generating a sawtooth wave with three harmonics. In this paper, we present the results and issues of the beam dynamics of the LEBT system.

  15. Index grating lifetime in photorefractive GaAs

    NASA Technical Reports Server (NTRS)

    Cheng, Li-Jen; Partovi, Afshin

    1988-01-01

    The index grating lifetime in liquid encapsulated Czochralski-grown undoped semi-insulating GaAs was measured using a beam coupling technique. The largest lifetime measure was about 8 s under a read beam intensity of 0.7 mW/sq cm with the grating periodicity being 0.63 microns. The measured value decreases to milliseconds as the read beam intensity and the grating periodicity increase to about 10 mW/sq cm and 4 microns, respectively. This range of grating lifetime in this material is adequate for its use in real-time spatial light modulators, reconfigurable beam steering devices, and dynamic memory elements, for optical computing. In addition, the results suggest that the lifetime is sensitive to residual imperfections in the crystal.

  16. Adding Fluorescence Lifetime Spectroscopy to the Tool Kit used to Study the Formation and Degradation of Luminescent Quantum Dots in Solution.

    PubMed

    Lyons, Taeyjuana Y; Williams, Denise N; Rosenzweig, Zeev

    2017-02-28

    The increasing commercialization of consumer electronic products that make use of II-VI semiconductor quantum dots (QD) has raised significant concerns about their impact on natural systems and human health once released to the environment at the end of their product's lifetime. In this paper, we demonstrate the addition of fluorescence lifetime spectroscopy to the existing tool kit of spectroscopic techniques to quantitatively monitor changes in QD properties as they form and degrade in solution. Our study reveals that due to its rich information content, fluorescence lifetime spectroscopy has a limited utility as a stand-alone technique in studying QD formation and degradation. However, combining fluorescence lifetime spectroscopy with commonly used emission quantum yield, and peak width measurements along with other analytical methods - including UV-VIS, TEM, and ICP-MS measurements significantly enhances the existing analytical tool kit and provides the capability to monitor in real time, the formation and degradation of luminescent QD in organic and aqueous solutions under environmentally relevant conditions.

  17. Experimental study on full-scale steel beam-to-column moment connections

    NASA Astrophysics Data System (ADS)

    Qian, Jiaru; Yu, Haiqun; Yan, Feng; Dong, Hai; Li, Jianhua; Liu, Yueming

    2005-12-01

    Ten full-scale steel beam-to-column moment connections used in moment-resisting frames (MRFs) were tested to study the failure process, failure mode, strength and plastic rotation capacity. The specimens include one traditional welded flange-bolted web connection, one traditional fully welded connection, four beam flange strengthened connections, three beam flange weakened connections, and one through-diaphragm connection. The test results show that the connections with flange cover plates or with partly cut beam flanges satisfy the beam plastic rotation demand for ductile MRFs. From the measured stress profiles along the beam flange and beam web depth, the mechanics of brittle fracture at the end of the beam is discussed. Design recommendations for steel beam-to-column moment connections are proposed.

  18. Lifetime report of perceived stress at work and cancer among men: A case-control study in Montreal, Canada.

    PubMed

    Blanc-Lapierre, Audrey; Rousseau, Marie-Claude; Weiss, Deborah; El-Zein, Mariam; Siemiatycki, Jack; Parent, Marie-Élise

    2017-03-01

    The association between perceived workplace psychological stress, over the entire work career, and cancer among men has never been assessed. This was explored in the context of a population-based case-control study conducted in Montreal, Canada. 3103 incident cancer cases (11 types) diagnosed in 1979-1985 and 512 population controls were interviewed. Subjects described in detail each job held during their lifetime, including the occurrence of stress, and its reason. Logistic regression estimated odds ratios (OR) and 95% confidence intervals (CI) for the association between perceived workplace stress and its duration, and each cancer site, adjusting for lifestyle and occupational factors. Employment in at least one stressful job was associated with increased odds of cancers of the lung (OR=1.33, 95% CI: 1.01-1.75), colon (OR=1.51, 95% CI: 1.15-1.98), bladder (OR=1.37, 95% CI: 1.03-1.81), rectal (OR=1.52, 95% CI: 1.10-2.10), and stomach (OR=1.53, 95% CI: 1.08-2.15). A duration-response trend was found for cancers of the lung, colon, rectum, stomach, and for NHL. Subjects reported changes in stress level over their career. Perceived stress was ascribed to several sources, including high demand and time pressure, financial issues, job insecurity, and hazardous conditions. Prolonged exposure to perceived stress at work was associated with greater odds of cancer at 5 out of 11 sites. While over reporting of stress by cases cannot be fully ruled out, these associations, if substantiated, would bear important public health significance. Prospective studies building on detailed stress assessment protocols considering all sources and changes over the career are necessary. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Association of Overweight with the Prevalence of Lifetime Psychiatric Disorders and Suicidality: General Population-based Study in Korea.

    PubMed

    Kim, Byung Soo; Chang, Sung Man; Seong, Su Jeong; Park, Jee Eun; Park, Subin; Hong, Jin Pyo; Bae, Jae Nam; Cho, Seong Jin; Hahm, Bong Jin; Lee, Dong Woo; Park, Jong Ik; Lee, Jun Young; Jeon, Hong Jin; Cho, Maeng Je

    2016-11-01

    Many epidemiological studies suggest that overweight is associated with an elevated risk of psychiatric disorders and suicidal tendency. However, findings vary across studies, and some have contradictory results. We investigated the relationship of overweight with a range of psychiatric disorders and suicidality in the Korean general population. A multistage cluster sampling design was adopted. A total of 6,022 participants aged 18-74 years completed face-to-face interviews (response rate: 78.7%) including assessment of psychiatric disorders, suicidality, and height and weight. Overweight (defined as body mass index of ≥ 25) was associated with an increase in the lifetime prevalence of depressive disorders (adjusted odds ratio [AOR] 1.38; 95% confidence interval [CI], 1.07-1.77), suicidal ideation (AOR, 1.42; 95% CI, 1.20-1.68), and suicidal plans (AOR, 1.44; 95% CI, 1.02-2.03), controlling for sociodemographic variables. Subgroup analysis found that the association between overweight and depressive disorders exists only in women aged 18-44 years (AOR, 1.75; 95% CI, 1.07-2.89) while the association of overweight with suicidal ideation (AOR, 2.08; 95% CI, 1.53-2.82) and suicide plans (AOR, 2.59; 95% CI, 1.25-5.37) existed only in men aged 18-44 years. Overweight was associated with increased odds of nicotine use disorders in women aged 18-44 years (AOR, 2.35; 95% CI, 1.02-5.43), but the association was in the opposite direction in men aged 45-74 years (AOR, 0.64; 95% CI, 0.43-0.94). In conclusion, overweight is related to various psychiatric disorders and suicidality in Korea. Policy makers and clinicians should pay more attention to the mental health of overweight individuals.

  20. Association of Overweight with the Prevalence of Lifetime Psychiatric Disorders and Suicidality: General Population-based Study in Korea

    PubMed Central

    2016-01-01

    Many epidemiological studies suggest that overweight is associated with an elevated risk of psychiatric disorders and suicidal tendency. However, findings vary across studies, and some have contradictory results. We investigated the relationship of overweight with a range of psychiatric disorders and suicidality in the Korean general population. A multistage cluster sampling design was adopted. A total of 6,022 participants aged 18–74 years completed face-to-face interviews (response rate: 78.7%) including assessment of psychiatric disorders, suicidality, and height and weight. Overweight (defined as body mass index of ≥ 25) was associated with an increase in the lifetime prevalence of depressive disorders (adjusted odds ratio [AOR] 1.38; 95% confidence interval [CI], 1.07–1.77), suicidal ideation (AOR, 1.42; 95% CI, 1.20–1.68), and suicidal plans (AOR, 1.44; 95% CI, 1.02–2.03), controlling for sociodemographic variables. Subgroup analysis found that the association between overweight and depressive disorders exists only in women aged 18–44 years (AOR, 1.75; 95% CI, 1.07–2.89) while the association of overweight with suicidal ideation (AOR, 2.08; 95% CI, 1.53–2.82) and suicide plans (AOR, 2.59; 95% CI, 1.25–5.37) existed only in men aged 18–44 years. Overweight was associated with increased odds of nicotine use disorders in women aged 18–44 years (AOR, 2.35; 95% CI, 1.02–5.43), but the association was in the opposite direction in men aged 45–74 years (AOR, 0.64; 95% CI, 0.43–0.94). In conclusion, overweight is related to various psychiatric disorders and suicidality in Korea. Policy makers and clinicians should pay more attention to the mental health of overweight individuals. PMID:27709862

  1. Lifetimes of lunar satellite orbits

    NASA Technical Reports Server (NTRS)

    Meyer, Kurt W.; Buglia, James J.; Desai, Prasun N.

    1994-01-01

    The Space Exploration Initiative has generated a renewed interest in lunar mission planning. The lunar missions currently under study, unlike the Apollo missions, involve long stay times. Several lunar gravity models have been formulated, but mission planners do not have enough confidence in the proposed models to conduct detailed studies of missions with long stay times. In this report, a particular lunar gravitational model, the Ferrari 5 x 5 model, was chosen to determine the lifetimes for 100-km and 300-km perilune altitude, near-circular parking orbits. The need to analyze orbital lifetimes for a large number of initial orbital parameters was the motivation for the formulation of a simplified gravitational model from the original model. Using this model, orbital lifetimes were found to be heavily dependent on the initial conditions of the nearly circular orbits, particularly the initial inclination and argument of perilune. This selected model yielded lifetime predictions of less than 40 days for some orbits, and other orbits had lifetimes exceeding a year. Although inconsistencies and limitations are inherent in all existing lunar gravity models, primarily because of a lack of information about the far side of the moon, the methods presented in this analysis are suitable for incorporating the moon's nonspherical gravitational effects on the preliminary design level for future lunar mission planning.

  2. Lifetime studies of 130nm nMOS transistors intended for long-duration, cryogenic high-energy physics experiments.

    SciTech Connect

    Hoff, J.R.; Arora, R.; Cressler, J.D.; Deptuch, G.W.; Gui, P.; Lourenco, N.E.; Wu, G.; Yarema, R.J.; /Fermilab

    2011-12-01

    Future neutrino physics experiments intend to use unprecedented volumes of liquid argon to fill a time projection chamber in an underground facility. To increase performance, integrated readout electronics should work inside the cryostat. Due to the scale and cost associated with evacuating and filling the cryostat, the electronics will be unserviceable for the duration of the experiment. Therefore, the lifetimes of these circuits must be well in excess of 20 years. The principle mechanism for lifetime degradation of MOSFET devices and circuits operating at cryogenic temperatures is via hot carrier degradation. Choosing a process technology that is, as much as possible, immune to such degradation and developing design techniques to avoid exposure to such damage are the goals. This requires careful investigation and a basic understanding of the mechanisms that underlie hot carrier degradation and the secondary effects they cause in circuits. In this work, commercially available 130nm nMOS transistors operating at cryogenic temperatures are investigated. The results show that the difference in lifetime for room temperature operation and cryogenic operation for this process are not great and the lifetimes at both 300K and at 77K can be projected to more than 20 years at the nominal voltage (1.5V) for this technology.

  3. Lifetime and g-factor measurements of excited states using Coulomb excitation and alpha transfer reactions

    SciTech Connect

    Guevara, Z. E. Torres, D. A.

    2016-07-07

    In this contribution the challenges in the use of a setup to simultaneously measure lifetimes and g-factor values will be presented. The simultaneous use of the transient field technique and the Doppler Shift Attenuation Method, to measure magnetic moments and lifetimes respectively, allows to obtain a complete characterization of the currents of nucleons and the deformation in excited states close to the ground state. The technique is at the moment limited to Coulomb excitation and alpha-transfer reactions, what opens an interesting perspective to consider this type of experiments with radioactive beams. The use of deep-inelastic and fusion-evaporation reactions will be discussed. An example of a setup that makes use of a beam of {sup 106}Cd to study excited states of {sup 110}Sn and the beam nuclei itself will be presented.

  4. Lifetime and g-factor measurements of excited states using Coulomb excitation and alpha transfer reactions

    NASA Astrophysics Data System (ADS)

    Guevara, Z. E.; Torres, D. A.

    2016-07-01

    In this contribution the challenges in the use of a setup to simultaneously measure lifetimes and g-factor values will be presented. The simultaneous use of the transient field technique and the Doppler Shift Attenuation Method, to measure magnetic moments and lifetimes respectively, allows to obtain a complete characterization of the currents of nucleons and the deformation in excited states close to the ground state. The technique is at the moment limited to Coulomb excitation and alpha-transfer reactions, what opens an interesting perspective to consider this type of experiments with radioactive beams. The use of deep-inelastic and fusion-evaporation reactions will be discussed. An example of a setup that makes use of a beam of 106Cd to study excited states of 110Sn and the beam nuclei itself will be presented.

  5. Proposal of a beam study in the AGS Booster

    SciTech Connect

    Machida, S.; Chen, S.

    1991-10-01

    IN order to achieve the design luminosity, the Superconducting Super Collider (SSC) parameter choices emphasize the preservation of the transverse emittance requiring in the collider a normalized transverse emittance of 1 {pi}.mm.mrad. A stringent accelerator chain emittance budget must be maintained to achieve the final value. Budgeted emittance specifications for the Low Energy Booster (LEB) include 0.4 {pi}.mm.mrad at injection and {le} 0.6 {pi}.mm.mrad at extraction. The space-charge tune shift is expected to be more than 0.5 when the rms normalized emittance of 0.4 {pi}.mm.mrad at injection and the total number of particles is 1.1 {times} 10{sup 12} with 1 {times} 10{sup 10} particles per bunch. Therefore, it is necessary to cope with a large tune shift and avoid emittance deterioration. We have been studying the beam emittance evolution in the LEB by a multi-particle simulation code with space-charge effects. As reported in the several papers we have obtained from the simulation some new insights into the effects which seem to explain qualitatively a cause of the emittance growth. Even quantitatively, we believe that the simulation can predict the emittance growth as a function of time quite accurately because the code includes most details of the physics processes, such as the adiabatic bunching process and acceleration in the fully 6-D phase space treatment, transverse as well as longitudinal space-charge calculations in a self-consistent manner, and intensity decrease due to particle loss. The purpose of this study is to determine quantitatively the emittance deterioration due to space-charge effects, not to find the maximum current an accelerator could accommodate. Since the charge distribution itself may not remain the same, an accurate measurement of the beam profile is an essential factor of the beam study.

  6. Protochlorophyll complexes with similar steady-state fluorescence characteristics can differ in fluorescence lifetimes. A model study in Triton X-100.

    PubMed

    Myśliwa-Kurdziel, Beata; Solymosi, Katalin; Kruk, Jerzy; Böddi, Béla; Strzałka, Kazimierz

    2007-03-01

    The steady-state and time-resolved fluorescence characteristics of protochlorophyll (Pchl) dissolved in neat Triton X-100 and in Triton X-100 micelles were investigated, and the fluorescence lifetimes of different Pchl spectral forms were studied. Varying the concentration of Pchl or diluting the micellar solutions either with a buffer or with a micellar solution, 631-634, 645-655, 680-692 and above 700 nm emitting Pchl complexes were prepared, the ratios of which varied from one another. The fluorescence decay of the 631-634 nm emitting (monomeric) form had a mono-exponential character with a 5.4-ns fluorescence lifetime. The long-wavelength Pchl complexes (aggregates) had two fluorescence lifetime values within a range of 1.4-3.9 ns and 0.15-0.84 ns, which showed high variability in different environments. Depending on the conditions, either mono- or double-exponential fluorescence decay was found for a fluorescence band at 680-685 nm. These data show that despite their very similar steady-state fluorescence properties, Pchl complexes can differ in fluorescence lifetimes, which may reflect different molecular structures, intrinsic geometries or different molecular interactions. This underlines the importance of complex spectroscopic analysis for a precise description of native and artificial chlorophyllous pigment forms.

  7. Study of Charge Distribution in a Dust Beam using a Faraday Cup Assembly

    SciTech Connect

    Kausik, S.S.; Dutta, P.; Chakraborty, M.; Kakati, M.; Saikia, B.K.

    2005-10-31

    A Faraday cup assembly is employed to study the charge distribution in a dust beam. The Faraday Cup scans the dust beam across its diameter and the dust particle current is noted in an Electrometer. The variation of the pico ampere current, carried by the charged dust particles in the beam, is studied with change in the gas pressure. The observations provide an insight into the variation of the charge to mass ratio in a dust beam.

  8. Lifetime adiposity and risk of pancreatic cancer in the NIH-AARP Diet and Health Study cohort.

    PubMed

    Stolzenberg-Solomon, Rachael Z; Schairer, Catherine; Moore, Steve; Hollenbeck, Albert; Silverman, Debra T

    2013-10-01

    The association of excess body weight across a lifetime with pancreatic cancer has not been examined extensively. We determined the association for body mass index (BMI) at different ages and adiposity duration and gain with incident pancreatic adenocarcinoma in the NIH-AARP Diet and Health Study cohort. Participants aged 50-71 y completed questionnaires at baseline (1995-1996) and 6 months later that queried height and weight history. We calculated HRs and 95% CIs by using Cox proportional hazards models adjusted for age, smoking, sex, and intakes of energy and total fat. Over an average follow-up of 10.5 y, 1206 and 2122 pancreatic cancer cases were identified in the subcohort who completed the second questionnaire (n = 273,975) and the baseline cohort (n = 501,698), respectively. Compared with normal weight, overweight or obesity at ages 18, 35, 50, or >50 y (baseline BMI) was significantly associated with pancreatic cancer, with HRs ranging from 1.15 to 1.53. A longer duration of BMI (in kg/m(2)) >25.0 was significantly associated with pancreatic cancer (overall HR per 10-y increment of duration: 1.06; 95% CI: 1.02, 1.09), with individuals who reported diabetes having the greatest risk (HR per 10-y increment of duration: 1.18; 95% CI: 1.05, 1.32; P-interaction = 0.01) and rates. A substantial gain in adiposity (>10 kg/m(2)) after age 50 y was significantly associated with increased pancreatic cancer risk. The etiologic fraction of pancreatic cancer explained by adiposity at any age was 14% overall and 21% in never smokers. Overweight and obesity at any age are associated with increased pancreatic cancer.

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

    PubMed Central

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

    2014-01-01

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

  10. Lifestyle and metabolic syndrome in adult survivors of childhood cancer: a report from the St. Jude Lifetime Cohort Study

    PubMed Central

    Smith, Webb A.; Li, Chenghong; Nottage, Kerri; Mulrooney, Daniel A.; Armstrong, Gregory T.; Lanctot, Jennifer Q.; Chemaitilly, Wassim; Laver, Joseph H.; Srivastava, Deo Kumar; Robison, Leslie L.; Hudson, Melissa M.; Ness, Kirsten K.

    2014-01-01

    Background Childhood cancer survivors (CCS) are at increased risk for the metabolic syndrome (MetSyn), which may be reduced with lifestyle modifications. The purpose of this investigation was to characterize lifestyle habits and associations with the MetSyn among CCS. Methods CCS ≥10 years from diagnosis, older than 18 years of age, and participating in the St. Jude Lifetime Cohort Study completed medical and laboratory tests and a food frequency questionnaire (FFQ). The Third National Cholesterol Education Program Adult Treatment Panel (NCEP-ATPIII) criteria were used to classify participants with MetSyn. Anthropometric, FFQ and self-reported physical activity data were used to characterize lifestyle habits according to World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) recommendations. Those who met ≥4 of 7 recommendations were classified as following guidelines. Sex stratified log-binomial regression models were used to evaluate associations between dietary/lifestyle habits and MetSyn, adjusted for age, age at cancer diagnosis, cranial radiation, education, and household income. Results Among 1598 CCS (49.2% male, median age 32.7 years, range, 18.9–60.0 years), 31.8% met criteria for MetSyn and 27.0 % followed WCRF/AICR guidelines. Females who did not follow WCRF/AICR guidelines were 2.4 (95% CI 1.7–3.3) and males were 2.2 (95% CI 1.6–3.0) times more likely to have MetSyn than those who followed WCRF/AICR guidelines. Conclusion Adherance to a heart healthy lifestyle is associated with lower risk of MetSyn among CCS. There is a need to determine if lifestyle interventions prevent or remediate MetSyn in CCS. PMID:25070001

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

    PubMed

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

    2014-01-01

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

  12. Lifestyle and metabolic syndrome in adult survivors of childhood cancer: a report from the St. Jude Lifetime Cohort Study.

    PubMed

    Smith, Webb A; Li, Chenghong; Nottage, Kerri A; Mulrooney, Daniel A; Armstrong, Gregory T; Lanctot, Jennifer Q; Chemaitilly, Wassim; Laver, Joseph H; Srivastava, Deo Kumar; Robison, Leslie L; Hudson, Melissa M; Ness, Kirsten K

    2014-09-01

    Childhood cancer survivors (CCS) are at an increased risk of developing metabolic syndrome (MetSyn), which may be reduced with lifestyle modifications. The purpose of this investigation was to characterize lifestyle habits and associations with MetSyn among CCS. CCS who were ≥ 10 years from diagnosis, aged > 18 years, and participating in the St. Jude Lifetime Cohort Study completed medical and laboratory tests and a food frequency questionnaire. The Third Report of the National Cholesterol Education Program Adult Treatment Panel criteria were used to classify participants with MetSyn. Anthropometric, food frequency questionnaire, and self-reported physical activity data were used to characterize lifestyle habits according to World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) recommendations. Those who met ≥ 4 of 7 recommendations were classified as having followed guidelines. Sex-stratified log-binomial regression models were used to evaluate associations between dietary/lifestyle habits and MetSyn, adjusted for age, age at cancer diagnosis, receipt of cranial radiotherapy, education, and household income. Among 1598 CCS (49.2% of whom were male, with a median age of 32.7 years [range, 18.9 years-60.0 years]), 31.8% met criteria for MetSyn and 27.0% followed WCRF/AICR guidelines. Females who did not follow WCRF/AICR guidelines were 2.4 times (95% confidence interval, 1.7-3.3) and males were 2.2 times (95% confidence interval, 1.6-3.0) more likely to have MetSyn than those who followed WCRF/AICR guidelines. Adherence to a heart-healthy lifestyle is associated with a lower risk of MetSyn among CCS. There is a need to determine whether lifestyle interventions prevent or remediate MetSyn in CCS. © 2014 American Cancer Society.

  13. Lifetime opiate exposure as an independent and interactive cardiovascular risk factor in males: a cross-sectional clinical study

    PubMed Central

    Reece, Albert S; Hulse, Gary K

    2013-01-01

    Introduction While several studies have identified an increased incidence of cardiovascular disorders in opiate dependence, neither opiates as a cardiovascular risk factor nor their effect on central arterial function has been considered. Methods Pulse wave analysis (SphygmoCor, AtCorMedical Pty Limited, Sydney, NSW, Australia) was undertaken on a cohort of controls and opiate dependent patients and the results compared to their lifetime opiate exposure. Results Controls (N = 401) were compared with 465 opiate dependent men. The mean (log) ages were different and were found to be 28.80 ± 0.49 years versus 35.02 ± 0.39 years (P < 0.0001), respectively. Of the opiate dependent group, 87.7% were treated with buprenorphine, 8.8% with methadone, and 3.4% with naltrexone. Multiple regression analysis was used to adjust for chronologic age (CA). At CA of 60 years, the modeled age in the controls was 66.40 years, and that in the addicted group was 73.11 years, an advancement of 6.71 years, or 10.10%. Exacerbations of age dependent changes in central arterial stiffness, central pressures, pulse rate, ejection duration, diastolic duration, and subendocardial perfusion ratio by opiate dependence were all noted (P < 0.05). Current heroin dose, heroin duration, and the dose duration interaction were all significantly related to the vascular (or “reference”) age (RA)/CA ratio (all P < 0.006). After multivariate adjustment, the opiate dose duration was independently predictive of RA (P < 0.02). Opiate dose and/or duration were included in a further 25 terms. Conclusion These data show that opiate use is not benign for the male cardiovascular system, but has a dose response relationship to central arterial stiffness and thus cardiovascular aging, acting independently and interactively with established cardiovascular risk factors. These findings imply accelerated organismal aging. PMID:24124373

  14. Nuclear structure studies with gamma-ray beams

    DOE PAGES

    Tonchev, Anton; Bhatia, Chitra; Kelley, John; ...

    2015-05-28

    In stable and weakly bound neutron-rich nuclei, a resonance-like concentration of dipole states has been observed for excitation energies below the neutron-separation energy. This clustering of strong dipole states has been named the Pygmy Dipole Resonance (PDR) in contrast to the Giant Dipole Resonance (GDR) that dominates the E1 response. Understanding the PDR is presently of great interest in nuclear structure and nuclear astrophysics. High-sensitivity studies of E1 and M1 transitions in closed-shell nuclei using monoenergetic and 100% linearly-polarized photon beams are presented.

  15. An approach to fundamental study of beam loss minimization

    SciTech Connect

    Jameson, R.A. )

    1999-06-01

    The accelerator design rules involving rms matching, developed at CERN in the 1970[close quote]s, are discussed. An additional rule, for equipartitioning the beam energy among its degrees of freedom, may be added to insure an rms equilibrium condition. If the strong stochasticity threshold is avoided, as it is in realistic accelerator designs, the dynamics is characterized by extremely long transient settling times, making the role of equipartitioning hard to explain. An approach to systematic study using the RFQ accelerator as a simulation testbed is discussed. New methods are available from recent advances in research on complexity, nonlinear dynamics, and chaos. [copyright] [ital 1999 American Institute of Physics.

  16. Beam storage studies in the Fermilab main ring

    SciTech Connect

    MacLachlan, J.A.

    1982-05-06

    Bunched beams of 100 and 150 GeV have been stored in the Fermilab Main Ring for periods of up to one hour. The observations of beam current and beam profiles are analyzed for the effects of gas scattering, chromaticity and non-linear magnetic field.

  17. Fluorescence lifetime imaging ophthalmoscopy.

    PubMed

    Dysli, Chantal; Wolf, Sebastian; Berezin, Mikhail Y; Sauer, Lydia; Hammer, Martin; Zinkernagel, Martin S

    2017-09-01

    Imaging techniques based on retinal autofluorescence have found broad applications in ophthalmology because they are extremely sensitive and noninvasive. Conventional fundus autofluorescence imaging measures fluorescence intensity of endogenous retinal fluorophores. It mainly derives its signal from lipofuscin at the level of the retinal pigment epithelium. Fundus autofluorescence, however, can not only be characterized by the spatial distribution of the fluorescence intensity or emission spectrum, but also by a characteristic fluorescence lifetime function. The fluorescence lifetime is the average amount of time a fluorophore remains in the excited state following excitation. Fluorescence lifetime imaging ophthalmoscopy (FLIO) is an emerging imaging modality for in vivo measurement of lifetimes of endogenous retinal fluorophores. Recent reports in this field have contributed to our understanding of the pathophysiology of various macular and retinal diseases. Within this review, the basic concept of fluorescence lifetime imaging is provided. It includes technical background information and correlation with in vitro measurements of individual retinal metabolites. In a second part, clinical applications of fluorescence lifetime imaging and fluorescence lifetime features of selected retinal diseases such as Stargardt disease, age-related macular degeneration, choroideremia, central serous chorioretinopathy, macular holes, diabetic retinopathy, and retinal artery occlusion are discussed. Potential areas of use for fluorescence lifetime imaging ophthalmoscopy will be outlined at the end of this review. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. Nuclear Structure Studies with Stable and Radioactive Beams: The SPES radioactive ion beam project

    NASA Astrophysics Data System (ADS)

    de Angelis, G.; SPES Collaboration; Prete, G.; Andrighetto, A.; Manzolaro, M.; Corradetti, S.; Scarpa, D.; Rossignoli, M.; Monetti, A.; Lollo, M.; Calderolla, M.; Vasquez, J.; Zafiropoulos, D.; Sarchiapone, L.; Benini, D.; Favaron, P.; Rigato, M.; Pegoraro, R.; Maniero, D.; Calabretta, L.; Comunian, M.; Maggiore, M.; Lombardi, A.; Piazza, L.; Porcellato, A. M.; Roncolato, C.; Bisoffi, G.; Pisent, A.; Galatà, A.; Giacchini, M.; Bassato, G.; Canella, S.; Gramegna, F.; Valiente, J.; Bermudez, J.; Mastinu, P. F.; Esposito, J.; Wyss, J.; Russo, A.; Zanella, S.

    2015-04-01

    A new Radioactive Ion Beam (RIB) facility (SPES) is presently under construction at the Legnaro National Laboratories of INFN. The SPES facility is based on the ISOL method using an UCx Direct Target able to sustain a power of 10 kW. The primary proton beam is provided by a high current Cyclotron accelerator with energy of 35-70 MeV and a beam current of 0.2-0.5 mA. Neutron-rich radioactive ions are produced by proton induced fission on an Uranium target at an expected fission rate of the order of 1013 fissions per second. After ionization and selection the exotic isotopes are re-accelerated by the ALPI superconducting LINAC at energies of 10A MeV for masses in the region A=130 amu. The expected secondary beam rates are of the order of 107 - 109 pps. Aim of the SPES facility is to deliver high intensity radioactive ion beams of neutron rich nuclei for nuclear physics research as well as to be an interdisciplinary research centre for radio-isotopes production for medicine and for neutron beams.

  19. RF impedance studies of a beam chamber and longitudinally slot-coupled vacuum pumping antechamber

    SciTech Connect

    Kustom, R.L.; Nicholls, G.L.; Kramer, S.L.; Khoe, T.K.; Cook, J.M.

    1987-01-01

    The storage ring vacuum chamber of the proposed 7-GeV synchrotron light source at Argonne National Laboratory is planned to have a semi-elliptical beam chamber, with a longitudinal slot coupled to an antechamber containing NEG pumping strips. Concern over the RF impedance of this complex chamber has stimulated the need to understand the limitations it will have on the beam intensity, the RF acceleration system and on the beam lifetime. Calculations using numerical EM field programs have estimated the waveguide modes of this chamber and the impedance and loss parameter for the expected 1 to 2 cm beam bunch length. The loss parameter is shown to differ little from an elliptical beam chamber without the slot and antechamber. An experimental program has begun to verify the estimates of the impedance for these complex vacuum chamber components using laboratory methods. Preliminary results are presented for the measured loss parameter for a short length of beam vacuum chamber and for other components. These results are compared with their calculated values.

  20. Vacancy-type defects induced by grinding of Si wafers studied by monoenergetic positron beams

    SciTech Connect

    Uedono, Akira; Yoshihara, Nakaaki; Mizushima, Yoriko; Kim, Youngsuk; Nakamura, Tomoji; Ohba, Takayuki; Oshima, Nagayasu; Suzuki, Ryoichi

    2014-10-07

    Vacancy-type defects introduced by the grinding of Czochralski-grown Si wafers were studied using monoenergetic positron beams. Measurements of Doppler broadening spectra of the annihilation radiation and the lifetime spectra of positrons showed that vacancy-type defects were introduced in the surface region (<98 nm), and the major defect species were identified as (i) relatively small vacancies incorporated in dislocations and (ii) large vacancy clusters. Annealing experiments showed that the defect concentration decreased with increasing annealing temperature in the range between 100 and 500°C. After 600–700°C annealing, the defect-rich region expanded up to about 170 nm, which was attributed to rearrangements of dislocation networks, and a resultant emission of point defects toward the inside of the sample. Above 800°C, the stability limit of those vacancies was reached and they started to disappear. After the vacancies were annealed out (900°C), oxygen-related defects were the major point defects and they were located at <25 nm.

  1. Comparative Study on Flexural Strengthening of RC Beams using CFRP Laminate by Different Techniques

    NASA Astrophysics Data System (ADS)

    Jeevan, N.; Jagannatha Reddy, H. N.

    2017-08-01

    This paper presents a detailed study on flexural behaviour of RC beams strengthened using Carbon Fiber Reinforced Polymer (CFRP) laminate. A detailed study was made on strengthened beam using Externally Bonded Laminate (EBL) and Internally Bonded Laminate (IBL) techniques. In IBL technique the laminate is sandwiched between the layers of epoxy mounted on the cover portion by the groove. The beams were designed as under-reinforced section. Totally six beams were casted, out of this two beams were control beams. Strengthened beams were divided into two sets (IBL and EBL) of two beams each. The main aim of this work is to delay the debonding failure in order to enhance the ultimate load carrying capacity for strengthened beams. Four-point bending flexural tests were conducted on specimens up to failure. The experimental results illustrate that, the strengthened beams significantly increases the cracking, working and ultimate load when compared with control beams. IBL technique shows the significant increase in the debonding strain by delaying the beam from debonding failure which in turn enhances the ultimate load by almost 73% compared with control beam and 39% with EBL technique. All the deflection values from the experiments are within the limit of codal provisions. The IBL technique was emerged as the better strengthening technique, which increases almost 41% of working load (Pw) compared with strengthening codes.

  2. A Lifetime Prevalence of Comorbidity Between Bipolar Affective Disorder and Anxiety Disorders: A Meta-analysis of 52 Interview-based Studies of Psychiatric Population

    PubMed Central

    Nabavi, Behrouz; Mitchell, Alex J.; Nutt, David

    2015-01-01

    Background Bipolar affective disorder has a high rate of comorbidity with a multitude of psychiatric disorders and medical conditions. Among all the potential comorbidities, co-existing anxiety disorders stand out due to their high prevalence. Aims To determine the lifetime prevalence of comorbid anxiety disorders in bipolar affective disorder under the care of psychiatric services through systematic review and meta-analysis. Method Random effects meta-analyses were used to calculate the lifetime prevalence of comorbid generalised anxiety disorder, panic disorder, social anxiety disorder, specific phobia, agoraphobia, obsessive compulsive disorder and posttraumatic stress disorder in bipolar affective disorder. Results 52 studies were included in the meta-analysis. The rate of lifetime comorbidity was as follows: panic disorder 16.8% (95% CI 13.7–20.1), generalised anxiety disorder 14.4% (95% CI 10.8–18.3), social anxiety disorder13.3% (95% CI 10.1–16.9), post-traumatic stress disorder 10.8% (95% CI 7.3–14.9), specific phobia 10.8% (95% CI 8.2–13.7), obsessive compulsive disorder 10.7% (95% CI 8.7–13.0) and agoraphobia 7.8% (95% CI 5.2–11.0). The lifetime prevalence of any anxiety disorders in bipolar disorder was 42.7%. Conclusions Our results suggest a high rate of lifetime concurrent anxiety disorders in bipolar disorder. The diagnostic issues at the interface are particularly difficult because of the substantial symptom overlap. The treatment of co-existing conditions has clinically remained challenging. PMID:26629535

  3. A Lifetime Prevalence of Comorbidity Between Bipolar Affective Disorder and Anxiety Disorders: A Meta-analysis of 52 Interview-based Studies of Psychiatric Population.

    PubMed

    Nabavi, Behrouz; Mitchell, Alex J; Nutt, David

    2015-10-01

    Bipolar affective disorder has a high rate of comorbidity with a multitude of psychiatric disorders and medical conditions. Among all the potential comorbidities, co-existing anxiety disorders stand out due to their high prevalence. To determine the lifetime prevalence of comorbid anxiety disorders in bipolar affective disorder under the care of psychiatric services through systematic review and meta-analysis. Random effects meta-analyses were used to calculate the lifetime prevalence of comorbid generalised anxiety disorder, panic disorder, social anxiety disorder, specific phobia, agoraphobia, obsessive compulsive disorder and posttraumatic stress disorder in bipolar affective disorder. 52 studies were included in the meta-analysis. The rate of lifetime comorbidity was as follows: panic disorder 16.8% (95% CI 13.7-20.1), generalised anxiety disorder 14.4% (95% CI 10.8-18.3), social anxiety disorder13.3% (95% CI 10.1-16.9), post-traumatic stress disorder 10.8% (95% CI 7.3-14.9), specific phobia 10.8% (95% CI 8.2-13.7), obsessive compulsive disorder 10.7% (95% CI 8.7-13.0) and agoraphobia 7.8% (95% CI 5.2-11.0). The lifetime prevalence of any anxiety disorders in bipolar disorder was 42.7%. Our results suggest a high rate of lifetime concurrent anxiety disorders in bipolar disorder. The diagnostic issues at the interface are particularly difficult because of the substantial symptom overlap. The treatment of co-existing conditions has clinically remained challenging.

  4. Study and design of beam expander with wide aperture

    NASA Astrophysics Data System (ADS)

    Guo, Ming; Jin, Guangyong; Cai, Jixing; Zhang, Wei; Wei, Zhi

    2014-12-01

    In order to improve the capacity of beam collimation for laser beam expander, it is necessary to design a more reasonable and feasible structure of beam expander system. Laser beam expander is used to compress the laser divergence angle, in order to reduce the energy losing in long distance scanning acquisition system. This paper introduces the working principle and design idea of the laser beam expander, the collimating multiplying power focal length and the collimated magnification formula of expander main, secondary mirror. According to the third-order aberration theory, Considering the spherical aberration, sine difference and divergence angle, the reasonable analysis of optical path, ZEMAX optical design software was used to design large-diameter laser beam expander and analysis and optimize, And given the actual design data and results. Display the maximum optical path difference is +/-0.01λ of the main light ray and each light ray. To combination the rear- group objective lens of Galileo and Kepler beam expander, a large-diameter(1.475m) laser beam expander was designed with 0.2m in the diameter, 1/2m in the relative caliber. In the objective lens System, a high-order aspherical was used to the aberration of extra-axial point. we can see that the image quality is close to the diffraction limit from the curves of wavefront. In addition to improve image quality effectively, the system has the characteristics of simple structure, less costly and less design difficulty to compare with the other beam expanding system. And make the output beam's divergence angle smaller, energy density higher, and the beam quality has been greatly improved. The results show that the beam expander is fully meet the design requirements, the use effect is good. Design and research of laser beam expanding system not only improves the quality of the laser beam in the laser system, but also enlarge the application field of laser technology in photoelectric system.

  5. Beam-foil spectroscopy

    SciTech Connect

    Berry, H.G.; Hass, M.

    1982-01-01

    A brief survey of some applications of beam-foil spectroscopy is presented. Among the topics covered are lifetime and magnetic moment measurements, nuclear alignment, and polarized light production. (AIP)

  6. High-spin nuclear structure studies with radioactive ion beams

    SciTech Connect

    Baktash, C.

    1992-12-31

    Two important developments in the sixties, namely the advent of heavy-ion accelerators and fabrication of Ge detectors, opened the way for the experimental studies of nuclear properties at high angular momentum. Addition of a new degree of freedom, namely spin, made it possible to observe such fascinating phenomena as occurrences and coexistence of a variety of novel shapes, rise, fall and occasionally rebirth of nuclear collectivity, and disappearance of pairing correlations. Today, with the promise of development of radioactive ion beams (RIB) and construction of the third-generation Ge-detection systems (GAMMASPHERE and EUROBALL), the authors are poised to explore new and equally fascinating phenomena that have been hitherto inaccessible. With the addition of yet another dimension, namely the isospin, they will be able to observe and verify predictions for exotic shapes as varied as rigid triaxiality, hyperdeformation and triaxial octupole shapes, or to investigate the T = 0 pairing correlations. In this paper, they shall review, separately for neutron-deficient and neutron-rich nuclei, these and a few other new high-spin physics opportunities that may be realized with RIB. Following this discussion, they shall present a list of the beam species, intensities and energies that are needed to fulfill these goals. The paper will conclude with a description of the experimental techniques and instrumentations that are required for these studies.

  7. Study of Synchrotron Radiation for the Electron Beam Polarimeter for the MEIC

    SciTech Connect

    Sullivan, M.

    2015-08-06

    This is a look at the synchrotron radiation coming from the chicane in the electron beam line for the MEIC design. The power density on the beam pipe as well as transmission through the beam pipe is studied. The optics design is version 12.

  8. Study of bonding methods for flip chip and beam leaded devices

    NASA Technical Reports Server (NTRS)

    Rudd, H. C.; Colbert, D. C.

    1971-01-01

    The results are presented of a comprehensive study and evaluation for the bonding of flip chip and beam leaded devices onto hybrid microcircuit substrates used in high reliability space applications. The program included the evaluation of aluminum flip chips, solder (silver/tin) bump chips, gold beam leaded devices, and aluminum beam leaded devices.

  9. Studies of Limits on Uncontrolled Heavy Ion Beam Losses for Allowing Hands-On Maintenance

    SciTech Connect

    Reginald M. Ronningen; Igor Remec

    2010-09-11

    Dose rates from accelerator components activated by 1 W/m beam losses are obtained semiempirically for a 1 GeV proton beam and by use of Monte Carlo transport codes for the proton beam and for 777 MeV/u 3He, 500 MeV/u 48Ca, 86Kr, 136Xe, and 400 MeV/u 238U ions. The dose rate obtained by the semi-empirical method, 0.99 mSv/h (99 mrem/h) at 30 cm, 4 h after 100 d irradiation by a 1-GeV proton beam, is consistent with studies at several accelerator facilities and with adopted hands-on maintenance dose rate limits. Monte Carlo simulations verify this result for protons and extend studies to heavy ion beam losses in drift-tube linac and superconducting linac accelerating structures. The studies indicate that the 1 W/m limit imposed on uncontrolled beam losses for high-energy proton beams might be relaxed for heavy ion beams. These studies further suggest that using the ratio of neutrons produced by a heavy ion beam to neutrons produced by a proton beam along with the dose rate from the proton beam (for thin-target scenarios) should allow an estimate of the dose rates expected from heavy ion beam losses.

  10. Laboratory studies of the charge neutralization of a rocket payload during electron beam emission

    NASA Technical Reports Server (NTRS)

    Bernstein, W.; Whalen, B. A.; Harris, F. R.; Mcnamara, A. G.; Konradi, A.

    1980-01-01

    The charge neutralization of an electrically-isolated rocket payload emitting an energetic electron beam has been studied in experiments in the large vacuum chamber at Johnson Space Center. The introduction of an RF-discharge-produced ambient plasma density (10,000 to 50,000 per cu cm) reduces the payload potential to 200 V for low current (1 and 10 ma) beams. The ignition of the beam-plasma discharge provides an efficient neutralization process for higher current beams.

  11. Simulation study of interactions of Space Shuttle-generated electron beams with ambient plasmas

    NASA Technical Reports Server (NTRS)

    Lin, Chin S.

    1992-01-01

    This report summarizes results obtained through the support of NASA Grant NAGW-1936. The objective of this report is to conduct large scale simulations of electron beams injected into space. The topics covered include the following: (1) simulation of radial expansion of an injected electron beam; (2) simulations of the active injections of electron beams; (3) parameter study of electron beam injection into an ionospheric plasma; and (4) magnetosheath-ionospheric plasma interactions in the cusp.

  12. Fluorescence lifetime imaging microscopy (flimscopy). Methodology development and application to studies of endosome fusion in single cells.

    PubMed Central

    Oida, T; Sako, Y; Kusumi, A

    1993-01-01

    A new method of fluorescence microscopy for cell imaging has been developed that takes advantage of the spatial variations of fluorescence lifetimes in single cells as a source of image contrast, and thus it is named "fluorescence lifetime imaging microscopy (flimscopy)". Since time-resolved fluorescence measurements are sensitive to molecular dynamics and interactions, flimscopy allows the molecular information to be visualized in single cells. In flimscopy measurements, several (nanosecond) time-resolved fluorescence images of a sample are obtained at various delay times after pulsed laser excitation of the microscope's entire field of view. Lifetimes are calculated pixel-by-pixel from these time-resolved images, and the spatial variations of the lifetimes are then displayed in a pseudocolor format (flimscopy image). The total data acquisition time needed to obtain a flimscopy image with the diffraction-limited spatial resolution (approximately 250 nm) is decreased to just approximately 30 s for approximately 300 fluorescent molecules/micron2. This was achieved by developing a high-frequency (400 kHz) nanosecond-gating (9 ns full width at half height)-signal accumulation system. This technique allows the extent of resonance energy transfer to be visualized in single living cells, and is free from the errors due to variations in path length, light scattering, and the number of fluorophores that necessitate complex corrections in steady-state microfluorometry and fluorescence ratio imaging microscopy. Flimscopy was applied here to observe the extent of fusion of individual endosomes in single cells. Results revealed the occurrence of extensive fusion between primary endocytic vesicles and/or sorting endosomes, thereby raising the possibility that the biogenesis of sorting endosomes involves multiple fusions of primary endocytic vesicles. Images FIGURE 6 FIGURE 4 PMID:8471720

  13. Measurement of the Omega0(c) lifetime

    SciTech Connect

    Iori, M.; Ayan, A.S.; Akgun, U.; Alkhazov, G.; Amaro-Reyes, J.; Atamantchouk, A.G.; Balatz, M.Y.; Blanco-Covarrubias, A.; Bondar, N.F.; Cooper, P.S.; Dauwe, L.J.; /Ball State U. /Bogazici U. /Carnegie Mellon U. /Rio de Janeiro, CBPF /Fermilab /Serpukhov, IHEP /Beijing, Inst. High Energy Phys. /Moscow, ITEP /Heidelberg, Max Planck Inst. /Moscow State U. /St. Petersburg, INP

    2007-01-01

    The authors report a precise measurement of the {Omega}{sub c}{sup 0} lifetime. The data were taken by the SELEX (E781) experiment using 600 GeV/c {Sigma}{sup -}, {pi}{sup -} and p beams. The measurement has been made using 83 {+-} 19 reconstructed {Omega}{sub c}{sup 0} in the {Omega}{sup -} {pi}{sup -}{pi}{sup +}{pi}{sup +} and {Omega}{sup -} {pi}{sup +} decay modes. The lifetime of the {Omega}{sub c}{sup 0} is measured to be 65 {+-} 13(stat) {+-} 9(sys) fs.

  14. Career readiness in adult survivors of childhood cancer: a report from the St. Jude Lifetime Cohort study

    PubMed Central

    Strauser, David; Klosky, James L.; Brinkman, Tara M.; Wong, Alex W.K.; Chan, Fong; Lanctot, Jennifer Q.; Ojha, Rohit P.; Robison, Leslie L.; Hudson, Melissa M.; Ness, Kirsten K.

    2014-01-01

    Purpose Adult survivors of childhood cancer experience difficulties in obtaining and maintaining employment. Employment-related challenges are associated with treatment-related health conditions, and may also be related to vocational factors such as career readiness, skill acquisition, and work experience. Unfortunately, little is known about how treatment, health and vocational related factors interact to impact career development among childhood cancer survivors. Methods 385 adult survivors of childhood cancer (42.1% male, median age 38 (21-62) years), participating in the St. Jude Lifetime Cohort study, completed a work experiences survey that included measures of career readiness and vocational identity. Logistic regression was used to compare characteristics of survivors in the low career readiness category to those in the medium or high career readiness category, and structural equation modeling (SEM) was utilized to evaluate associations between career readiness, vocational identity, treatment intensity and physical/emotional health. Results Low career readiness was prevalent in 17.4% of survivors. Univariate analysis did not identify any significant associations between cancer treatment-related factors and career readiness. Unemployed survivors (Odds ratio (OR) 2.3, 95% Confidence Interval (CI) 1.2-4.5), those who were not college graduates (OR 3.0, 95% CI 1.6-5.6), and those who had no personal income (OR 5.9, 95% CI 1.7-30.9) were at increased risk of low career readiness. SEM indicated that associations between treatment intensity, physical health, age at diagnosis and career readiness were mediated by emotional health and vocational identity. 63%, 35%, and 10% of the variance in career readiness, vocational identity, and emotional health, respectively, were explained by this theoretical model. Conclusions The results of this study indicate that individuals who reported low levels of career readiness were more likely to be unemployed, earn less than $40

  15. Career readiness in adult survivors of childhood cancer: a report from the St. Jude Lifetime Cohort Study.

    PubMed

    Strauser, David; Klosky, James L; Brinkman, Tara M; Wong, Alex W K; Chan, Fong; Lanctot, Jennifer; Ojha, Rohit P; Robison, Leslie L; Hudson, Melissa M; Ness, Kirsten K

    2015-03-01

    Adult survivors of childhood cancer experience difficulties in obtaining and maintaining employment. Employment-related challenges are associated with treatment-related health conditions and may also be related to vocational factors such as career readiness, skill acquisition, and work experience. Unfortunately, little is known about how treatment-, health-, and vocational-related factors interact to impact career development among childhood cancer survivors. Three hundred eighty-five adult survivors of childhood cancer (42.1% male, median age 38 years (21-62)), participating in the St. Jude Lifetime Cohort Study, completed a work experiences survey that included measures of career readiness and vocational identity. Logistic regression was used to compare characteristics of survivors in the low career readiness category to those in the medium or high career readiness category, and structural equation modeling (SEM) was utilized to evaluate associations between career readiness, vocational identity, treatment intensity, and physical/emotional health. Low career readiness was prevalent in 17.4% of survivors. Univariate analysis did not identify any significant associations between cancer treatment-related factors and career readiness. Unemployed survivors (odds ratio (OR) 2.3, 95% confidence interval (CI) 1.2-4.5), those who were not college graduates (OR 3.0, 95% CI 1.6-5.6), and those who had no personal income (OR 5.9, 95% CI 1.7-30.9) were at increased risk of low career readiness. SEM indicated that associations between treatment intensity, physical health, age at diagnosis, and career readiness were mediated by emotional health and vocational identity. Sixty-three, 35, and 10% of the variance in career readiness, vocational identity, and emotional health, respectively, were explained by this theoretical model. The results of this study indicate that individuals who reported low levels of career readiness were more likely to be unemployed and earn less than US

  16. Cryogenic Lifetime Studies of 130 nm and 65 nm CMOS Technologies for High-Energy Physics Experiments

    SciTech Connect

    Hoff, James R.; Deptuch, G. W.; Wu, Guoying; Gui, Ping

    2015-06-04

    The Long Baseline Neutrino Facility intends to use unprecedented volumes of liquid argon to fill a time projection chamber in an underground facility. Research is under way to place the electronics inside the cryostat. For reasons of efficiency and economics, the lifetimes of these circuits must be well in excess of 20 years. The principle mechanism for lifetime degradation of MOSFET devices and circuits operating at cryogenic temperatures is hot carrier degradation. Choosing a process technology that is, as much as possible, immune to such degradation and developing design techniques to avoid exposure to such damage are the goals. This, then, requires careful investigation and a basic understanding of the mechanisms that underlie hot carrier degradation and the secondary effects they cause in circuits. In this work, commercially available 130 nm and 65 nm nMOS transistors operating at cryogenic temperatures are investigated. Our results show that both technologies achieve the lifetimes required by the experiment. Minimal design changes are necessary in the case of the 130 nm process and no changes whatsoever are necessary for the 65 nm process.

  17. Experimental studies of SPECT scintimammography with combined cone-beam and parallel-beam collimators

    NASA Astrophysics Data System (ADS)

    Krol, Andrzej; Feiglin, David H.; Gangal, K. R.; Coman, Ioana L.; Salgado, Roberto B.; Lipson, Edward D.; Karczewski, Deborah A.; Thomas, Frank D.

    2003-05-01

    Conventional SPECT Tc-99m sestamibi scintimammography (STSM) has limited clinical utility due to fairly low radiopharmaceutical uptake in the breast tissue as compared to the heart and the liver. We investigated the use of a cone-beam collimator (CBC) to STSM. Each detector on a multi-headed gamma camera can be equipped with parallel-beam (PBC) or cone-beam collimators (CBC). PBC can provide truncation-free SPECT projection sets, while CBC offers increased sensitivity in a limited field-of-view (FOV). Combined PBC and CBC SPECT ddata acquisition may provide improved lesion contrast and overall better imaging performance within CBC FOV with significantly reduced truncation artifacts in the reconstructed images. In this paper we evaluate the combined CBC&PBC SPECT method using a limited number of confirmed breast cancer patients and female chest phantoms with simulated breast lesions. We envision the combined CBC&PBC SPECT as a useful clinical tool in scintimammography.

  18. Cartesian beams.

    PubMed

    Bandres, Miguel A; Gutiérrez-Vega, Julio C

    2007-12-01

    A new and very general beam solution of the paraxial wave equation in Cartesian coordinates is presented. We call such a field a Cartesian beam. The complex amplitude of the Cartesian beams is described by either the parabolic cylinder functions or the confluent hypergeometric functions, and the beams are characterized by three parameters that are complex in the most general situation. The propagation through complex ABCD optical systems and the conditions for square integration are studied in detail. Applying the general expression of the Cartesian beams, we also derive two new and meaningful beam structures that, to our knowledge, have not yet been reported in the literature. Special cases of the Cartesian beams are the standard, elegant, and generalized Hermite-Gauss beams, the cosine-Gauss beams, the Lorentz beams, and the fractional order beams.

  19. Study of electron beam curing process using epoxy resin system

    NASA Astrophysics Data System (ADS)

    Nishitsuji, Delmo A.; Marinucci, Gerson; Evora, Maria C.; de Andrade e Silva, Leonardo G.

    2007-12-01

    Polymeric matrix composite (PMC) has been used in engineering applications instead of metal in the last few years, due to its corrosion resistance and excellent relation between tensile strength/density and elastic modulus/density. However, PMC materials cured by thermal process require high temperature and are time-consuming. The electron beam (EB) curing technology allows its use at room temperature and reduced curing times, and this is one of the main advantages over thermal technology. The aim of this work is to investigate electron beam curable epoxy formulations to use in filament winding processes to produce composite material with similar or better properties than thermal curable composites. The study has been made with commercial epoxy resins and cationic initiators. The epoxy resin samples were irradiated for few minutes with total dose of 150 kGy. The glass transition temperatures ( Tg) were determined by dynamic mechanical analyzer (DMA) and the result was 137 °C. The thermal process was carried out in a furnace following three steps: 4 h at 90 °C, increasing temperature from 90 °C to 130 °C during 4 h and 12 h at 130 °C. The total process time was 20 h. The Tg of this sample was 102 °C.

  20. Carrier lifetimes in silicon carbide

    NASA Astrophysics Data System (ADS)

    Nigam, Saurav

    measured as ˜2.3x10-15 cm2 and an upper value for the hole capture cross section was estimated as ˜10-19 cm2. The recombination rate of carriers was six orders of magnitude higher through the Z-defects as compared to the EH6/7 centers, thus, the former acted as lifetime limiting defect in the high quality epitaxial layers that were investigated in this research. The minority carrier lifetime in high quality epitaxial layers can be predicted with sufficient accuracy using a simple relationship between the lifetimes, tauMCL, and concentration of the Z-defect, N T (cm-3), expressed as tauMCL˜10 6/NT. The minority carrier lifetimes in the as-grown epitaxial layers (investigated in this research) were in 0.1--2 mus range corresponding to the Z-defect concentrations of 1011-10 12 cm-3. The temperature and injection rate dependence of carrier lifetimes were also simulated based on the Z-defect recombination parameters, and were in good agreement with the experimental data. The rate of carrier recombination via extended defects (threading edge and screw dislocations) was also measured for 4H-SiC epitaxial layers. The dislocation recombination velocity and effective dislocation core radius which characterize the rate of recombination through the dislocations were determined to be 105 cm/s and 2.5x10-5 cm, respectively. The carrier lifetimes were shown to be affected locally in the regions where the dislocation density was higher than a certain threshold density. The threshold dislocation density on the studied epilayer was 106 cm -2.

  1. Lifetimes of High-Spin States in 76Kr

    NASA Astrophysics Data System (ADS)

    Valiente-Dobon, J. J.; Svensson, C. E.; O'Leary, C. D.; Ragnarsson, I.; Andreoiu, C.; Austin, R. A. E.; Carpenter, M. P.; Dashdorj, D.; Finlay, P.; Freeman, S. J.; Garrett, P. E.; Goergen, A.; Greene, J.; Grinyer, G. F.; Hyland, B.; Jenkins, D.; Johnston-Theasby, F.; Joshi, P.; Kelsall, N. S.; Macchiavelli, A. O.; Moore, F.; Mukherjee, G.; Phillips, A. A.; Reviol, W.; Sarantites, D.; Schumaker, M. A.; Seweryniak, D.; Smith, M. B.; Wadsworth, R.; Ward, D.

    2005-04-01

    High-spin states in 7636Kr40 have been populated in the 40Ca(40Ca,4p)76Kr fusion-evaporation reaction at a beam energy of 165 MeV, and studied using the GAMMASPHERE and MICROBALL multi-detector arrays. The ground-state band and two signature-split negative-parity bands of 76Kr have been extended to ˜ 30hbar. Lifetime measurements using the Doppler-shift attenuation method indicate that the transition quadrupole moment of these three bands decrease as they approach their maximum-spin states.

  2. Experimental evaluation of the carrier lifetime in GaAs grown at low temperature

    SciTech Connect

    Pastor, A. A.; Serdobintsev, P. Yu.; Chaldyshev, V. V.

    2012-05-15

    The relaxation dynamics of nonequilibrium charge carriers in gallium arsenide epitaxial films grown by molecular-beam epitaxy at low temperatures has been studied. The growth conditions of the epitaxial layer provided an excess arsenic content of 1.2% in the layer. In a material of this kind, the carrier lifetime is <1 ps. To examine carrier relaxation in the femtosecond range, an original scheme for measuring the refractive index dynamics was developed on the basis of the pump-probe technique. The lifetime of nonequilibrium charge carriers was evaluated to be (200 {+-} 35) fs.

  3. Experimental studies to test simple flexural neutralizers fitted to beams

    NASA Astrophysics Data System (ADS)

    Clark, P.; White, R. G.

    1994-10-01

    The control of vibration in one-dimensional structures is of considerable interest in practical engineering. With the majority of industrial machinery installations, it is this type of structure, for example, beams, pipework vibrating at low frequencies and other mechanical linkages, which forms one of the main vibration paths that bypass isolator systems. It is of interest to consider discontinuities that may be incorporated into these types of structure since they significantly affect the vibration characteristics of the complete installation. One such discontinuity that may be employed in vibration control is the vibration neutralizer. Previous work in this area of research has developed theoretical models of the neutralizer performance as a vibration control technique with particular reference to the effect of incorporating alternative mounting methods. In this work, complementary experimental studies are presented with a view to validating those theoretical studies previously undertaken.

  4. Energy deposition studies for the LBNE beam absorber

    SciTech Connect

    Rakhno, Igor L.; Mokhov, Nikolai V.; Tropin, Igor S.

    2015-01-29

    Results of detailed Monte Carlo energy deposition studies performed for the LBNE absorber core and the surrounding shielding with the MARS15 code are described. The model of the entire facility, that includes a pion-production target, focusing horns, target chase, decay channel, hadron absorber system – all with corresponding radiation shielding – was developed using the recently implemented ROOT-based geometry option in the MARS15 code. This option provides substantial flexibility and automation when developing complex geometry models. Both normal operation and accidental conditions were studied. Various design options were considered, in particular the following: (i) filling the decay pipe with air or helium; (ii) the absorber mask material and shape; (iii) the beam spoiler material and size. Results of detailed thermal calculations with the ANSYS code helped to select the most viable absorber design options.

  5. Experimental study of the stability of a neutralized electron beam

    SciTech Connect

    Kudelainen, V.I.; Parkhomchuk, V.V.; Pestrikov, D.V.

    1983-05-01

    Results are reported from measurements of the spectral properties of a long neutralized electron beam in the NAP-M proton storage ring. It is shown that when the number of secondary electrons is small, both the longitudinal and the transverse oscillations are strongly damped, so that beam instability is suppressed. The current density of the neutralized electron beam produced in the experiments was approx.10/sup 2/ times greater than the theoretical value determined from the instability threshold for nonaxisymmetric oscillations.

  6. Study on the bending behavior of preflex beam

    NASA Astrophysics Data System (ADS)

    Wan, Lijuan; Gao, Qilang

    2017-08-01

    Preflex beam with corrugated web is a new type of beam structure for bridge engineering which is composed by corrugated steel sheet and preflex beam. This kind of structure has advantages of high load bearing capacity, good endurance, small height-span ratio, light self-weight, long-span capacity and stiffener free. It has good economy and competitive ability for middle or small span bridges, such as Highway Bridge, overpass and Railway Bridge.

  7. Stroboscopic fluorescence lifetime imaging.

    PubMed

    Holton, Mark D; Silvestre, Oscar R; Errington, Rachel J; Smith, Paul J; Matthews, Daniel R; Rees, Paul; Summers, Huw D

    2009-03-30

    We report a fluorescence lifetime imaging technique that uses the time integrated response to a periodic optical excitation, eliminating the need for time resolution in detection. A Dirac pulse train of variable period is used to probe the frequency response of the total fluorescence per pulse leading to a frequency roll-off that is dependent on the relaxation rate of the fluorophores. The technique is validated by demonstrating wide-field, realtime, lifetime imaging of the endocytosis of inorganic quantum dots by a cancer cell line. Surface charging of the dots in the intra-cellular environment produces a switch in the fluorescence lifetime from approximately 40 ns to < 10 ns. A temporal resolution of half the excitation period is possible which in this instance is 15 ns. This stroboscopic technique offers lifetime based imaging at video rates with standard CCD cameras and has application in probing millisecond cell dynamics and in high throughput imaging assays.

  8. Study on electron beam in a low energy plasma focus

    SciTech Connect

    Khan, Muhammad Zubair; Ling, Yap Seong; San, Wong Chiow

    2014-03-05

    Electron beam emission was investigated in a low energy plasma focus device (2.2 kJ) using copper hollow anode. Faraday cup was used to estimate the energy of the electron beam. XR100CR X-ray spectrometer was used to explore the impact of the electron beam on the target observed from top-on and side-on position. Experiments were carried out at optimized pressure of argon gas. The impact of electron beam is exceptionally notable with two different approaches using lead target inside hollow anode in our plasma focus device.

  9. Transverse and longitudinal beam dynamics studies at the Fermilab photoinjector

    SciTech Connect

    Carneiro, J.P.; Barov, N.; Edwards, H.; Fitch, M.; Hartung, W.; Flottmann, K.; Schreiber, S.; Ferrario, M.; /Frascati

    2005-01-01

    The Fermilab photoinjector produces electron bunches of 1-12 nC charge with an energy of 16-18 MeV. Detailed measurements and optimization of the transverse emittance have been carried out for a number of beam line optics conditions, and at a number of beam line locations. The length of the bunches has also been measured, first for an uncompressed beam (as a function of the charge) and then for a compressed beam of 8 nC charge (as a function of the 9-cell cavity phase). These measurements are presented and compared with the simulation codes HOMDYN and ASTRA.

  10. A Theoretical Study of Microwave Beam Absorption by a Rectenna

    NASA Technical Reports Server (NTRS)

    Ott, J. H.; Rice, J. S.; Thorn, D. C.

    1981-01-01

    The theoretical operational parameters for the workable satellite power system were examined. The system requirements for efficient transmission and reception of an environmentally benign microwave beam were determined.

  11. Studies of beam injection with a compensated bump and uncompensated bump in a synchrotron

    SciTech Connect

    Akbar Fakhri, Ali; Prajapati, S. K.; Ghodke, A. D.; Singh, Gurnam

    2013-08-15

    Synchrotron radiation sources Indus-1 and Indus-2 have a synchrotron as the common injector. A three kicker compensated bump injection scheme was employed for beam injection into this synchrotron. The stored beam current in the synchrotron is higher, when all the three kickers are operated at the same current than when kickers are operated at currents required to generate compensated bump. Beam dynamics studies have been done to understand why this happens. Theoretical studies indicate that higher stored current in the later case is attributed to smaller residual oscillations of injected beam. These studies also reveal that if the angle of the injected beam during beam injection is kept varying, the performance could be further improved. This is experimentally confirmed by injecting the beam on rising part of the injection septum magnet current pulse.

  12. In-beam PET at high-energy photon beams: a feasibility study

    NASA Astrophysics Data System (ADS)

    Müller, H.; Enghardt, W.

    2006-04-01

    For radiation therapy with carbon ion beams, either for the stable isotope 12C or for the radioactive one 11C, it has been demonstrated that the β+-activity distribution created or deposited, respectively, within the irradiated volume can be visualized by means of positron emission tomography (PET). The PET images provide valuable information for quality assurance and precision improvement of ion therapy. Dedicated PET scanners have been integrated into treatment sites at the Heavy Ion Medical Accelerator at Chiba (HIMAC), Japan, and the Gesellschaft für Schwerionenforschung (GSI), Germany, to make PET imaging feasible during therapeutic irradiation (in-beam PET). A similar technique may be worthwhile for radiotherapy with high-energy bremsstrahlung. In addition to monitoring the dose delivery process which in-beam PET has been primarily developed for, it may be expected that radiation response of tissue can be detected by means of in-beam PET. We investigate the applicability of PET for treatment control in the case of using bremsstrahlung spectra produced by 15-50 MeV electrons. Target volume activation due to (γ, n) reactions at energies above 20 MeV yields moderate β+-activity levels, which can be employed for imaging. The radiation from positrons produced by pair production is not presently usable because the detectors are overloaded due to the low duty factor of medical electron linear accelerators. However, the degradation of images caused by positron motion between creation and annihilation seems to be tolerable.

  13. Lifetime and 12-month prevalence of eating disorders amongst women in mid-life: a population-based study of diagnoses and risk factors.

    PubMed

    Micali, Nadia; Martini, Maria G; Thomas, Jennifer J; Eddy, Kamryn T; Kothari, Radha; Russell, Ellie; Bulik, Cynthia M; Treasure, Janet

    2017-01-17

    Eating disorders (EDs) are common amongst women; however, no research has specifically investigated the lifetime/12-month prevalence of eating disorders amongst women in mid-life (i.e., fourth and fifth decade of life) and the relevant longitudinal risk factors. We aimed to investigate the lifetime and 12-month prevalence of EDs and lifetime health service use and to identify childhood, parenting, and personality risk factors. This is a two-phase prevalence study, nested within an existing longitudinal community-based sample of women in mid-life. A total of 5658 women from the UK Avon Longitudinal Study of Parents and Children (ALSPAC; enrolled 20 years earlier) participated. ED diagnoses were obtained using validated structured interviews. Weighted analyses were carried out accounting for the two-phase methodology to obtain prevalence figures and to carry out risk factor regression analyses. By mid-life, 15.3% (95% confidence intervals, 13.5-17.4%) of women had met criteria for a lifetime ED. The 12-month prevalence of EDs was 3.6%. Childhood sexual abuse was prospectively associated with all binge/purge type disorders and an external locus of control was associated with binge-eating disorder. Better maternal care was protective for bulimia nervosa. Childhood life events and interpersonal sensitivity were associated with all EDs. By mid-life a significant proportion of women will experience an ED, and few women accessed healthcare. Active EDs are common in mid-life, both due to new onset and chronic disorders. Increased awareness of the full spectrum of EDs in this stage of life and adequate service provision is important. This is the first study to investigate childhood and personality risk factors for full threshold and sub-threshold EDs and to identify common predictors for full and sub-threshold EDs. Further research should clarify the role of preventable risk factors on both full and sub-threshold EDs.

  14. A review of dosimetry studies on external-beam radiation treatment with respect to second cancer induction

    PubMed Central

    Xu, X George; Bednarz, Bryan; Paganetti, Harald

    2014-01-01

    It has been long known that patients treated with ionizing radiation carry a risk of developing a second cancer in their lifetimes. Factors contributing to the recently renewed concern about the second cancer include improved cancer survival rate, younger patient population as well as emerging treatment modalities such as intensity-modulated radiation treatment (IMRT) and proton therapy that can potentially elevate secondary exposures to healthy tissues distant from the target volume. In the past 30 years, external-beam treatment technologies have evolved significantly, and a large amount of data exist but appear to be difficult to comprehend and compare. This review article aims to provide readers with an understanding of the principles and methods related to scattered doses in radiation therapy by summarizing a large collection of dosimetry and clinical studies. Basic concepts and terminology are introduced at the beginning. That is followed by a comprehensive review of dosimetry studies for external-beam treatment modalities including classical radiation therapy, 3D-conformal x-ray therapy, intensity-modulated x-ray therapy (IMRT and tomotherapy) and proton therapy. Selected clinical data on second cancer induction among radiotherapy patients are also covered. Problems in past studies and controversial issues are discussed. The needs for future studies are presented at the end. PMID:18540047

  15. The cumulative burden of surviving childhood cancer: an initial report from the St Jude Lifetime Cohort Study (SJLIFE).

    PubMed

    Bhakta, Nickhill; Liu, Qi; Ness, Kirsten K; Baassiri, Malek; Eissa, Hesham; Yeo, Frederick; Chemaitilly, Wassim; Ehrhardt, Matthew J; Bass, Johnnie; Bishop, Michael W; Shelton, Kyla; Lu, Lu; Huang, Sujuan; Li, Zhenghong; Caron, Eric; Lanctot, Jennifer; Howell, Carrie; Folse, Timothy; Joshi, Vijaya; Green, Daniel M; Mulrooney, Daniel A; Armstrong, Gregory T; Krull, Kevin R; Brinkman, Tara M; Khan, Raja B; Srivastava, Deo K; Hudson, Melissa M; Yasui, Yutaka; Robison, Leslie L

    2017-09-07

    Survivors of childhood cancer develop early and severe chronic health conditions (CHCs). A quantitative landscape of morbidity of survivors, however, has not been described. We aimed to describe the cumulative burden of curative cancer therapy in a clinically assessed ageing population of long-term survivors of childhood cancer. The St Jude Lifetime Cohort Study (SJLIFE) retrospectively collected data on CHCs in all patients treated for childhood cancer at the St Jude Children's Research Hospital who survived 10 years or longer from initial diagnosis and were 18 years or older as of June 30, 2015. Age-matched and sex-frequency-matched community controls were used for comparison. 21 treatment exposure variables were included in the analysis, with data abstracted from medical records. 168 CHCs for all participants were graded for severity using a modified Common Terminology Criteria of Adverse Events. Multiple imputation with predictive mean matching was used for missing occurrences and grades of CHCs in the survivors who were not clinically evaluable. Mean cumulative count was used for descriptive cumulative burden analysis and marked-point-process regression was used for inferential cumulative burden analysis. Of 5522 patients treated for childhood cancer at St Jude Children's Research Hospital who had complete records, survived 10 years or longer, and were 18 years or older at time of study, 3010 (54·5%) were alive, had enrolled, and had had prospective clinical assessment. 2512 (45·5%) of the 5522 patients were not clinically evaluable. The cumulative incidence of CHCs at age 50 years was 99·9% (95% CI 99·9-99·9) for grade 1-5 CHCs and 96·0% (95% CI 95·3-96·8%) for grade 3-5 CHCs. By age 50 years, a survivor had experienced, on average, 17·1 (95% CI 16·2-18·1) CHCs of any grade, of which 4·7 (4·6-4·9) were CHCs of grade 3-5. The cumulative burden in matched community controls of grade 1-5 CHCs was 9·2 (95% CI 7·9-10·6; p<0·0001 vs total study

  16. Comments on Injector Proton Beam Study in Run 2014

    SciTech Connect

    Zhang, S. Y.

    2014-09-15

    During the entire period of injector proton study in run 2014, it seems that the beam transverse emittance out of Booster is larger than that in run 2013. The emittance measured at the BtA transfer line and also the transmission from Booster late to AGS late are presented for this argument. In addition to this problem, it seems that the multiturn Booster injection, which defines the transverse emittance, needs more attention. Moreover, for high intensity operations, the space charge effect may be already relevant in RHIC polarized proton runs. With the RHIC proton intensity improvement in the next several years, higher Booster input intensity is needed, therefore, the space charge effect at the Booster injection and early ramp may become a new limiting factor.

  17. Diagnostic studies of ion beam formation in inductively coupled plasma

    SciTech Connect

    Jacobs, Jenee L.

    2015-01-01

    This dissertation describes a variety of studies focused on the plasma and the ion beam in inductively coupled plasma mass spectrometry (ICP-MS). The ability to use ICP-MS for measurements of trace elements in samples requires the analytes to be efficiently ionized. Updated ionization efficiency tables are discussed for ionization temperatures of 6500 K and 7000 K with an electron density of 1 x 1015 cm-3. These values are reflective of the current operating parameters of ICP-MS instruments. Calculations are also discussed for doubly charged (M2+) ion formation, neutral metal oxide (MO) ionization, and metal oxide (MO+) ion dissociation for similar plasma temperature values. Ionization efficiency results for neutral MO molecules in the ICP have not been reported previously.

  18. Direct reaction experimental studies with beams of radioactive tin ions

    SciTech Connect

    Jones, K. L. Ayres, A.; Bey, A.; Burcher, S.; Cartegni, L.; Cerizza, G.; Ahn, S.; Allmond, J. M.; Beene, J. R.; Galindo-Uribarri, A.; Liang, J. F.; Nesaraja, C. D.; Pain, S. D.; Radford, D. C.; Schmitt, K. T.; Smith, M. S.; Stracener, D. W.; Varner, R. L.; Bardayan, D. W.; Baugher, T.; and others

    2015-10-15

    The tin chain of isotopes provides a unique region in which to investigate the evolution of single-particle structure, spreading from N = 50 at {sup 100}Sn, through 10 stable isotopes and the N = 82 shell closure at {sup 132}Sn out into the r-process path. Direct reactions performed on radioactive ion beams are sensitive spectroscopic tools for studying exotic nuclei. Here we present one experiment knocking out neutrons from tin isotopes that are already neutron deficient and two reactions that add a neutron to neutron-rich {sup 130}Sn. Both techniques rely on selective particle identification and the measurement of γ rays in coincidence with charged ions. We present the goals of the two experiments and the particle identification for the channels of interest. The final results will be presented in future publications.

  19. Study of nanoscale structural biology using advanced particle beam microscopy

    NASA Astrophysics Data System (ADS)

    Boseman, Adam J.

    This work investigates developmental and structural biology at the nanoscale using current advancements in particle beam microscopy. Typically the examination of micro- and nanoscale features is performed using scanning electron microscopy (SEM), but in order to decrease surface charging, and increase resolution, an obscuring conductive layer is applied to the sample surface. As magnification increases, this layer begins to limit the ability to identify nanoscale surface structures. A new technology, Helium Ion Microscopy (HIM), is used to examine uncoated surface structures on the cuticle of wild type and mutant fruit flies. Corneal nanostructures observed with HIM are further investigated by FIB/SEM to provide detailed three dimensional information about internal events occurring during early structural development. These techniques are also used to reconstruct a mosquito germarium in order to characterize unknown events in early oogenesis. Findings from these studies, and many more like them, will soon unravel many of the mysteries surrounding the world of developmental biology.

  20. Intra-beam scattering studies for low emittance at BAPS

    NASA Astrophysics Data System (ADS)

    Tian, Sai-Ke; Wang, Jiu-Qing; Xu, Gang; Jiao, Yi

    2015-06-01

    The target parameters of modern ultra-low emittance storage ring light sources are entering into a regime where intra-beam scattering (IBS) becomes important and, in the case of the Beijing Advanced Photon Source (BAPS), which is being designed at the Institute of High Energy Physics (IHEP), even a limitation for achieving the desired emittances in both transverse planes at the diffraction limit for X-ray wavelengths (≈10 pm). Due to the low emittance, the IBS effect will be very strong. Accurate calculations are needed to check if the design goal (ɛh+ɛv = 20 pm) can be reached. In this paper, we present the results of numerical simulation studies of the IBS effect on a BAPS temporary design lattice.

  1. Direct Reaction Experimental Studies with Beams of Radioactive Tin Ions

    SciTech Connect

    Jones, K. L.; Ahn, S.H.; Allmond, James M; Ayres, A.; Bardayan, Daniel W; Baugher, T.; Bazin, D.; Beene, James R; Berryman, J. S.; Bey, A.; Bingham, C. R.; Cartegni, L.; Chae, K. Y.; Gade, A.; Galindo-Uribarri, Alfredo {nmn}; Garcia-Ruiz, R.F.; Grzywacz, Robert Kazimierz; Howard, Meredith E; Kozub, R. L.; Liang, J Felix; Manning, Brett M; Matos, M.; McDaniel, S.; Miller, D.; Nesaraja, Caroline D; O'Malley, Patrick; Padgett, S; Padilla-Rodal, Elizabeth; Pain, Steven D; Pittman, S. T.; Radford, David C; Ratkiewicz, Andrew J; Schmitt, Kyle; Smith, Michael Scott; Stracener, Daniel W; Stroberg, S.; Tostevin, Jeffrey A; Varner Jr, Robert L; Weisshaar, D.; Wimmer, K.

    2015-01-01

    The tin chain of isotopes provides a unique region in which to investigate the evolution of single-particle structure, spreading from N = 50 at Sn-100, through 10 stable isotopes and the N = 82 shell closure at Sn-132 out into the r-process path. Direct reactions performed on radioactive ion beams are sensitive spectroscopic tools for studying exotic nuclei. Here we present one experiment knocking out neutrons from tin isotopes that are already neutron deficient and two reactions that add a neutron to neutron-rich Sn-130. Both techniques rely on selective particle identification and the measurement of gamma rays in coincidence with charged ions. We present the goals of the two experiments and the particle identification for the channels of interest. The final results will be presented in future publications.

  2. Radiological Studies for the LCLS Beam Abort System

    SciTech Connect

    Santana Leitner, M.; Vollaire, J.; Mao, X.S.

    2008-03-25

    The Linac Coherent Light Source (LCLS), a pioneer hard x-ray free electron laser is currently under construction at the Stanford Linear Accelerator Center. It is expected that by 2009 LCLS will deliver laser pulses of unprecedented brightness and short length, which will be used in several forefront research applications. This ambitious project encompasses major design challenges to the radiation protection like the numerous sources and the number of surveyed objects. In order to sort those, the showers from various loss sources have been tracked along a detailed model covering 1/2 mile of LCLS accelerator by means of the Monte Carlo intra nuclear cascade codes FLUKA and MARS15. This article covers the FLUKA studies of heat load; prompt and residual dose and environmental impact for the LCLS beam abort system.

  3. Cherenkov Excited Phosphorescence-based pO2 Estimation during Multi-beam Radiation Therapy: Phantom and Simulation Studies

    PubMed Central

    Esipova, Tatiana V.; Vinogradov, Sergei A.; Glaser, Adam K.; Gladstone, David J.; Pogue, Brian W.

    2014-01-01

    Megavoltage radiation beams used in External Beam Radiotherapy (EBRT) generate Cherenkov light emission in tissues and equivalent phantoms. This optical emission was utilized to excite an oxygen-sensitive phosphorescent probe, PtG4, which has been developed specifically for NIR lifetime-based sensing of the partial pressure of oxygen (pO2). Phosphorescence emission, at different time points with respect to the excitation pulse, was acquired by an intensifier-gated CCD camera synchronized with radiation pulses delivered by a medical linear accelerator. The pO2 distribution was tomographically recovered in a tissue-equivalent phantom during EBRT with multiple beams targeted from different angles at a tumor-like anomaly. The reconstructions were tested in two different phantoms that have fully oxygenated background, to compare a fully oxygenated and a fully deoxygenated inclusion. To simulate a realistic situation of EBRT, where the size and location of the tumor is well known, spatial information of a prescribed region was utilized in the recovery estimation. The phantom results show that region-averaged pO2 values were recovered successfully, differentiating aerated and deoxygenated inclusions. Finally, a simulation study was performed showing that pO2 in human brain tumors can be measured to within 15mmHg for edge depths less than 10-20mm using the Cherenkov Excited Phosphorescence Oxygen imaging (CEPhOx) method and PtG4 as a probe. This technique could allow non-invasive monitoring of pO2 in tumors during the normal process of EBRT, where beams are generally delivered from multiple angles or arcs during each treatment fraction. PMID:25146556

  4. Cherenkov excited phosphorescence-based pO2 estimation during multi-beam radiation therapy: phantom and simulation studies

    NASA Astrophysics Data System (ADS)

    Holt, Robert W.; Zhang, Rongxiao; Esipova, Tatiana V.; Vinogradov, Sergei A.; Glaser, Adam K.; Gladstone, David J.; Pogue, Brian W.

    2014-09-01

    Megavoltage radiation beams used in External Beam Radiotherapy (EBRT) generate Cherenkov light emission in tissues and equivalent phantoms. This optical emission was utilized to excite an oxygen-sensitive phosphorescent probe, PtG4, which has been developed specifically for NIR lifetime-based sensing of the partial pressure of oxygen (pO2). Phosphorescence emission, at different time points with respect to the excitation pulse, was acquired by an intensifier-gated CCD camera synchronized with radiation pulses delivered by a medical linear accelerator. The pO2 distribution was tomographically recovered in a tissue-equivalent phantom during EBRT with multiple beams targeted from different angles at a tumor-like anomaly. The reconstructions were tested in two different phantoms that have fully oxygenated background, to compare a fully oxygenated and a fully deoxygenated inclusion. To simulate a realistic situation of EBRT, where the size and location of the tumor is well known, spatial information of a prescribed region was utilized in the recovery estimation. The phantom results show that region-averaged pO2 values were recovered successfully, differentiating aerated and deoxygenated inclusions. Finally, a simulation study was performed showing that pO2 in human brain tumors can be measured to within 15 mmHg for edge depths less than 10-20 mm using the Cherenkov Excited Phosphorescence Oxygen imaging (CEPhOx) method and PtG4 as a probe. This technique could allow non-invasive monitoring of pO2 in tumors during the normal process of EBRT, where beams are generally delivered from multiple angles or arcs during each treatment fraction.

  5. Cherenkov excited phosphorescence-based pO2 estimation during multi-beam radiation therapy: phantom and simulation studies.

    PubMed

    Holt, Robert W; Zhang, Rongxiao; Esipova, Tatiana V; Vinogradov, Sergei A; Glaser, Adam K; Gladstone, David J; Pogue, Brian W

    2014-09-21

    Megavoltage radiation beams used in External Beam Radiotherapy (EBRT) generate Cherenkov light emission in tissues and equivalent phantoms. This optical emission was utilized to excite an oxygen-sensitive phosphorescent probe, PtG4, which has been developed specifically for NIR lifetime-based sensing of the partial pressure of oxygen (pO2). Phosphorescence emission, at different time points with respect to the excitation pulse, was acquired by an intensifier-gated CCD camera synchronized with radiation pulses delivered by a medical linear accelerator. The pO2 distribution was tomographically recovered in a tissue-equivalent phantom during EBRT with multiple beams targeted from different angles at a tumor-like anomaly. The reconstructions were tested in two different phantoms that have fully oxygenated background, to compare a fully oxygenated and a fully deoxygenated inclusion. To simulate a realistic situation of EBRT, where the size and location of the tumor is well known, spatial information of a prescribed region was utilized in the recovery estimation. The phantom results show that region-averaged pO2 values were recovered successfully, differentiating aerated and deoxygenated inclusions. Finally, a simulation study was performed showing that pO2 in human brain tumors can be measured to within 15 mmHg for edge depths less than 10-20 mm using the Cherenkov Excited Phosphorescence Oxygen imaging (CEPhOx) method and PtG4 as a probe. This technique could allow non-invasive monitoring of pO2 in tumors during the normal process of EBRT, where beams are generally delivered from multiple angles or arcs during each treatment fraction.

  6. Čerenkov radiation emission and excited luminescence (CREL) sensitivity during external beam radiation therapy: Monte Carlo and tissue oxygenation phantom studies.

    PubMed

    Zhang, Rongxiao; Glaser, Adam; Esipova, Tatiana V; Kanick, Stephen C; Davis, Scott C; Vinogradov, Sergei; Gladstone, David; Pogue, Brian W

    2012-10-01

    Radiotherapy generates Čerenkov radiation emission in tissue, and spectral absorption features appearing in the emission spectrum can be used to quantify blood oxygen saturation (S(t)O(2)) from the known absorptions of hemoglobin. Additionally, the Čerenkov light can be used to excite oxygen-sensitive phosphorescence of probe PtG4, whose emission lifetime directly reports on tissue oxygen partial pressure (pO(2)). Thus, it is feasible to probe both hemoglobin S(t)O(2) and pO(2) using external radiation therapy beam to create as an internal light source in tumor tissue. In this study, the sensitivity and spatial origins of these two signals were examined. Emission was detected using a fiber-optic coupled intensifier-gated CCD camera interfaced to a spectrometer. The phosphorescence lifetimes were quantified and compared with S(t)O(2) changes previously measured. Monte Carlo simulations of the linear accelerator beam were used together with tracking of the optical signals, to predict the spatial distribution and zone sensitivity within the phantom. As the fiber-to-beam distance (FBD) varied from 0 to 30 mm, i.e. the distance from the fiber tip to the nearest side of the radiotherapy beam, the effective sampling depth for CR emission changed from 4 to 29 mm for the wavelengths in the range of 600-1000 nm. For the secondary emission (phosphorescence) the effective sampling depth was determined to be in the range of 9 to 19 mm. These results indicate that sampling of S(t)O(2) and pO(2) in tissue should be feasible during radiation therapy, and that the radiation beam and fiber sampling geometry can be set up to acquire signals that originate as deep as a few centimeters in the tissue.

  7. Effect of current and lifetime posttraumatic stress disorder on 24-h urinary catecholamines and cortisol: results from the Mind Your Heart Study.

    PubMed

    Wingenfeld, Katja; Whooley, Mary A; Neylan, Thomas C; Otte, Christian; Cohen, Beth E

    2015-02-01

    Posttraumatic stress disorder (PTSD) is associated with an increased risk of cardiovascular disease and several other chronic illnesses. Alterations in the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis in PTSD might contribute to these associations but findings regarding SNS and HPA activity in PTSD are heterogeneous. We measured 24-h urinary catecholamines and cortisol in a large cohort of adult outpatients recruited from 2 Veterans Affairs medical centers. 24-h urinary norepinephrine, epinephrine, dopamine and cortisol were measured by tandem mass spectrometry. Lifetime and current PTSD were assessed with the Clinician Administered PTSD Scale using DSM-IV-TR criteria. Out of 613 participants, 199 (32.5%) had current PTSD, 100 (16.3%) had lifetime but not current PTSD, and 314 (51.2%) never had PTSD. Patients with current PTSD had significantly higher norepinephrine secretion compared to those without PTSD. Patients in the lifetime PTSD group exhibited lower cortisol values compared to those without PTSD. Participants who never had PTSD showed the lowest norepinephrine and the highest cortisol values. All results remained stable when controlling for potentially confounding variables. This study provides evidence for increased norepinephrine secretion and decreased cortisol in PTSD. Future longitudinal studies are needed to determine whether these changes contribute to adverse health outcomes in patients with PTSD. Published by Elsevier Ltd.

  8. Effect of current and lifetime posttraumatic stress disorder on 24-hour urinary catecholamines and cortisol: results from the Mind Your Heart Study

    PubMed Central

    Wingenfeld, Katja; Whooley, Mary A.; Neylan, Thomas C.; Otte, Christian; Cohen, Beth E.

    2014-01-01

    Summary Posttraumatic stress disorder (PTSD) is associated with an increased risk of cardiovascular disease and several other chronic illnesses. Alterations in the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis in PTSD might contribute to these associations but findings regarding SNS and HPA activity in PTSD are heterogeneous. We measured 24-hour urinary catecholamines and cortisol in a large cohort of adult outpatients recruited from 2 Veterans Affairs medical centers. 24-hour urinary norepinephrine, epinephrine, dopamine and cortisol were measured by tandem mass spectrometry. Lifetime and current PTSD were assessed with the Clinician Administered PTSD Scale using DSM-IV-TR criteria. Out of 613 participants, 199 (32.5%) had current PTSD, 100 (16.3%) had lifetime but not current PTSD, and 314 (51.2%) never had PTSD. Patients with current PTSD had significantly higher norepinephrine secretion compared to those without PTSD. Patients in the lifetime PTSD group exhibited lower cortisol values compared to those without PTSD. Participants who never had PTSD showed the lowest norepinephrine and the highest cortisol values. All results remained stable when controlling for potentially confounding variables. This study provides evidence for increased norepinephrine secretion and decreased cortisol in PTSD. Future longitudinal studies are needed to determine whether these changes contribute to adverse health outcomes in patients with PTSD. PMID:25459895

  9. Occupational self-coding and automatic recording (OSCAR): a novel web-based tool to collect and code lifetime job histories in large population-based studies.

    PubMed

    De Matteis, Sara; Jarvis, Deborah; Young, Heather; Young, Alan; Allen, Naomi; Potts, James; Darnton, Andrew; Rushton, Lesley; Cullinan, Paul

    2017-03-01

    Objectives The standard approach to the assessment of occupational exposures is through the manual collection and coding of job histories. This method is time-consuming and costly and makes it potentially unfeasible to perform high quality analyses on occupational exposures in large population-based studies. Our aim was to develop a novel, efficient web-based tool to collect and code lifetime job histories in the UK Biobank, a population-based cohort of over 500 000 participants. Methods We developed OSCAR (occupations self-coding automatic recording) based on the hierarchical structure of the UK Standard Occupational Classification (SOC) 2000, which allows individuals to collect and automatically code their lifetime job histories via a simple decision-tree model. Participants were asked to find each of their jobs by selecting appropriate job categories until they identified their job title, which was linked to a hidden 4-digit SOC code. For each occupation a job title in free text was also collected to estimate Cohen's kappa (κ) inter-rater agreement between SOC codes assigned by OSCAR and an expert manual coder. Results OSCAR was administered to 324 653 UK Biobank participants with an existing email address between June and September 2015. Complete 4-digit SOC-coded lifetime job histories were collected for 108 784 participants (response rate: 34%). Agreement between the 4-digit SOC codes assigned by OSCAR and the manual coder for a random sample of 400 job titles was moderately good [κ=0.45, 95% confidence interval (95% CI) 0.42-0.49], and improved when broader job categories were considered (κ=0.64, 95% CI 0.61-0.69 at a 1-digit SOC-code level). Conclusions OSCAR is a novel, efficient, and reasonably reliable web-based tool for collecting and automatically coding lifetime job histories in large population-based studies. Further application in other research projects for external validation purposes is warranted.

  10. Experimental beam system studies of plasma-polymer interactions

    NASA Astrophysics Data System (ADS)

    Nest, Dustin George

    Since the invention of the integrated circuit, the semiconductor industry has relied on the shrinking of device dimensions to increase device performance and decrease manufacturing costs. However, the high degree of roughening observed during plasma etching of current generation photoresist (PR) polymers can result in poor pattern transfer and ultimately decreased device performance or failure. Plasma-surface interactions are inherently difficult to study due to the highly coupled nature of the plasma enviroment. To better understand these interactions, a beam system approach is employed where polymers are exposed to beams of ions and vacuum ultraviolet (VUV) photons. Through the use of the beam system approach, simultaneous VUV radiation, ion bombardment, and moderate substrate heating have been identified as key elements, acting synergistically, as being responsible for roughening of current generation 193 nm PR during plasma processing. Sequential exposure is not adequate for the development of surface roughness, as observed through AFM and SEM. Ion bombardment results in the formation of a graphitized near-surface region with a depth of a few nanometers, the expected ion penetration depth of 150 eV argon ions. In contrast, VUV radiation results in the loss of carbon-oxygen bonds in the bulk PR as observed through Transmission FTIR. Based on the differing penetration depth of either ions or photons, their resulting chemical modifications, and the temperature dependence of the observed roughening, a mechanism is proposed based on stress relaxation resulting in surface buckling. The surface roughness of poly(4-methyl styrene) (P4MS) and poly(alpha-methyl styrene) (PalphaMS) have also been investigated under exposure to ions and VUV photons. PaMS degrades during VUV radiation above its ceiling temperature of ˜60°C. Despite having the same chemical composition as PalphaMS, P4MS does not degrade during VUV exposure at 70°C due to its relatively high ceiling

  11. Advanced Space Propulsion Study - Antiproton and Beamed Power Propulsion

    DTIC Science & Technology

    1987-10-01

    be combined into a single coherent laser beam and sent out to a transmitter lens floating between Saturn and Uranus . The transmitter lens would be a...produce coherent laser light, which would be collected into a single coherent beam and sent to a transmitter lens out between Saturn and Uranus . The

  12. Beam Simulation Studies of the LEBT for RIA Driver Linac

    SciTech Connect

    Zhao, Q.; Wu, X.; Andreev, V.; Balabin, A.; Doleans, M.; Gorelov, D.; Grimm, T.L.; Hartung, W.; Marti, F.; Schriber, S.O.; York, R.C.; Leitner, D.; Lyneis, C.M.

    2005-03-15

    The low energy beam transport (LEBT) system in the front-end of the Rare Isotope Accelerator (RIA) uses a 70 kV platform to pre-accelerate the ion beam from a 30 kV Electron Cyclotron Resonance (ECR) ion source, followed by an achromatic charge selection system. The selected beam is then pre-bunched and matched into the entrance of a Radio Frequency Quadrupole (RFQ) with a multi-harmonic buncher. To meet the beam power requirements for heavy ions, high current (several mA), multi-species beams will be extracted from the ECR. Therefore, it is crucial to control space charge effects in order to obtain the low emittance beam required for RIA. The PARMELA code is used to perform the LEBT simulations for the multi-species beams with 3D space charge calculations. The results of the beam dynamics simulations are presented, and the key issues of emittance growth in the LEBT and its possible compensation are discussed.

  13. Lifetime cancer risk and combined oral contraceptives: the Royal College of General Practitioners' Oral Contraception Study.

    PubMed

    Iversen, Lisa; Sivasubramaniam, Selvaraj; Lee, Amanda J; Fielding, Shona; Hannaford, Philip C

    2017-06-01

    Oral contraceptives have been used by hundreds of millions of women around the world. Important questions remain regarding the very long-term cancer risks that are associated with oral contraception. Despite previous research, important questions remain about the safety of these contraceptives: (1) How long do endometrial, ovarian, and colorectal cancer benefits persist? (2) Does combined oral contraceptive use during the reproductive years produce new cancer risks later in life? (3) What is the overall balance of cancer among past users as they enter the later stages of their lives? The purpose of this study was to examine the very long-term cancer risks or benefits associated with the use of combined oral contraceptives, including the estimated overall life-time balance. The 46,022 women who were recruited to the UK Royal College of General Practitioners' Oral Contraception Study in 1968 and 1969 were observed for up to 44 years. Directly standardized rates of specific and any cancer were calculated for "ever" and "never" users of combined oral contraceptives; data were standardized for age, parity, social class, and smoking. Attributable risk and preventive fraction percentages were calculated. Poisson regression that adjusted for the same variables was used to estimate incidence rate ratios between ever and never users and to examine effects by time since last oral contraceptive use. There were 4661 ever users with at least 1 cancer during 884,895 woman-years of observation and 2341 never users with at least 1 cancer during 388,505 woman-years of observation. Ever use of oral contraceptives was associated with reduced colorectal (incidence rate ratio, 0.81; 99% confidence interval, 0.66-0.99), endometrial (incidence rate ratio, 0.66; 99% confidence interval, 0.48-0.89), ovarian (incidence rate ratio, 0.67; 99% confidence interval, 0.50-0.89), and lymphatic and hematopoietic cancer (incidence rate ratio, 0.74; 99% confidence interval, 0.58-0.94). An increased

  14. Lifetimes of high-spin states in 74Kr

    SciTech Connect

    Valiente-Dobon, J. J.; Svensson, C. E.; Grinyer, G. F.; Hyland, B.; Phillips, A. A.; Schumaker, M. A.; Steinhardt, T.; Eberth, J.; Stefanescu, I.; Thelen, O.; Afanasjev, A. V.; Ragnarsson, I.; Andreoiu, C.; Austin, R. A. E.; Carpenter, M. P.; Freeman, S. J.; Moore, F.; Mukherjee, G.; Seweryniak, D.; Dashdorj, D.

    2006-04-26

    High-spin states in {sub 36}{sup 74}Kr{sub 38} were studied using the 40Ca(40Ca,{alpha}2p)74Kr fusion evaporation reaction at a beam energy of 165 MeV with GAMMASPHERE and MICROBALL and at a beam energy of 185 MeV with EUROBALL and ISIS multi-detector arrays. Lifetimes of the high-spin states for the ground-state band and the favoured negative-parity band have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments show a marginal decrease as a function of spin, suggesting that the rotational bands do not terminate at the maximum spin Imax.

  15. Comparative study of beam losses and heat loads reduction methods in MITICA beam source

    SciTech Connect

    Sartori, E. Agostinetti, P.; Dal Bello, S.; Marcuzzi, D.; Serianni, G.; Veltri, P.; Sonato, P.

    2014-02-15

    In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

  16. Comparative study of beam losses and heat loads reduction methods in MITICA beam source

    NASA Astrophysics Data System (ADS)

    Sartori, E.; Agostinetti, P.; Dal Bello, S.; Marcuzzi, D.; Serianni, G.; Sonato, P.; Veltri, P.

    2014-02-01

    In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

  17. Comparative study of beam losses and heat loads reduction methods in MITICA beam source.

    PubMed

    Sartori, E; Agostinetti, P; Dal Bello, S; Marcuzzi, D; Serianni, G; Sonato, P; Veltri, P

    2014-02-01

    In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

  18. Dual resolution cone beam breast CT: A feasibility study

    PubMed Central

    Chen, Lingyun; Shen, Youtao; Lai, Chao-Jen; Han, Tao; Zhong, Yuncheng; Ge, Shuaiping; Liu, Xinming; Wang, Tianpeng; Yang, Wei T.; Whitman, Gary J.; Shaw, Chris C.

    2009-01-01

    Purpose: In this study, the authors investigated the feasibility of a dual resolution volume-of-interest (VOI) cone beam breast CT technique and compared two implementation approaches in terms of dose saving and scatter reduction. Methods: With this technique, a lead VOI mask with an opening is inserted between the x-ray source and the breast to deliver x-ray exposure to the VOI while blocking x rays outside the VOI. A CCD detector is used to collect the high resolution projection data of the VOI. Low resolution cone beam CT (CBCT) images of the entire breast, acquired with a flat panel (FP) detector, were used to calculate the projection data outside the VOI with the ray-tracing reprojection method. The Feldkamp–Davis–Kress filtered backprojection algorithm was used to reconstruct the dual resolution 3D images. Breast phantoms with 180 μm and smaller microcalcifications (MCs) were imaged with both FP and FP-CCD dual resolution CBCT systems, respectively. Two approaches of implementing the dual resolution technique, breast-centered approach and VOI-centered approach, were investigated and evaluated for dose saving and scatter reduction with Monte Carlo simulation using a GEANT4 package. Results: The results showed that the breast-centered approach saved more breast absorbed dose than did VOI-centered approach with similar scatter reduction. The MCs in fatty breast phantom, which were invisible with FP CBCT scan, became visible with the FP-CCD dual resolution CBCT scan. Conclusions: These results indicate potential improvement of the image quality inside the VOI with reduced breast dose both inside and outside the VOI. PMID:19810473

  19. Dual resolution cone beam breast CT: a feasibility study.

    PubMed

    Chen, Lingyun; Shen, Youtao; Lai, Chao-Jen; Han, Tao; Zhong, Yuncheng; Ge, Shuaiping; Liu, Xinming; Wang, Tianpeng; Yang, Wei T; Whitman, Gary J; Shaw, Chris C

    2009-09-01

    In this study, the authors investigated the feasibility of a dual resolution volume-of-interest (VOI) cone beam breast CT technique and compared two implementation approaches in terms of dose saving and scatter reduction. With this technique, a lead VOI mask with an opening is inserted between the x-ray source and the breast to deliver x-ray exposure to the VOI while blocking x rays outside the VOI. A CCD detector is used to collect the high resolution projection data of the VOI. Low resolution cone beam CT (CBCT) images of the entire breast, acquired with a flat panel (FP) detector, were used to calculate the projection data outside the VOI with the ray-tracing reprojection method. The Feldkamp-Davis-Kress filtered backprojection algorithm was used to reconstruct the dual resolution 3D images. Breast phantoms with 180 microm and smaller microcalcifications (MCs) were imaged with both FP and FP-CCD dual resolution CBCT systems, respectively. Two approaches of implementing the dual resolution technique, breast-centered approach and VOI-centered approach, were investigated and evaluated for dose saving and scatter reduction with Monte Carlo simulation using a GEANT4 package. The results showed that the breast-centered approach saved more breast absorbed dose than did VOI-centered approach with similar scatter reduction. The MCs in fatty breast phantom, which were invisible with FP CBCT scan, became visible with the FP-CCD dual resolution CBCT scan. These results indicate potential improvement of the image quality inside the VOI with reduced breast dose both inside and outside the VOI.

  20. Lifetime risk of depression.

    PubMed

    Wittchen, H U; Knäuper, B; Kessler, R C

    1994-12-01

    Over the past decade, major epidemiological studies have been conducted to determine the prevalence of depressive syndromes, primarily major depression or dysthymia. The highest prevalences occur in younger cohorts (18-29 years); considerably lower prevalences are found in older individuals (45 years and above), with the lowest in those aged 65 and older. Several studies have confirmed an increase in the cumulative lifetime estimates of major depression in successively younger birth cohorts during this century. At the same time, questions have been raised about the low prevalence of depression in the elderly, including the role of confounding factors (e.g. differential morbidity and response-biased memory). Standardised diagnostic assessment procedures may be insufficiently adapted for use in the elderly. It has also been recognised that a substantial number of elderly individuals suffer from clinically relevant symptoms of depression but do not meet the criteria for major depression. Future research will be required to elucidate fully the apparently changing rates of depression.

  1. The costs of inequality: whole-population modelling study of lifetime inpatient hospital costs in the English National Health Service by level of neighbourhood deprivation

    PubMed Central

    Doran, Tim; Cookson, Richard

    2016-01-01

    Background There are substantial socioeconomic inequalities in both life expectancy and healthcare use in England. In this study, we describe how these two sets of inequalities interact by estimating the social gradient in hospital costs across the life course. Methods Hospital episode statistics, population and index of multiple deprivation data were combined at lower-layer super output area level to estimate inpatient hospital costs for 2011/2012 by age, sex and deprivation quintile. Survival curves were estimated for each of the deprivation groups and used to estimate expected annual costs and cumulative lifetime costs. Results A steep social gradient was observed in overall inpatient hospital admissions, with rates ranging from 31 298/100 000 population in the most affluent fifth of areas to 43 385 in the most deprived fifth. This gradient was steeper for emergency than for elective admissions. The total cost associated with this inequality in 2011/2012 was £4.8 billion. A social gradient was also observed in the modelled lifetime costs where the lower life expectancy was not sufficient to outweigh the higher average costs in the more deprived populations. Lifetime costs for women were 14% greater than for men, due to higher costs in the reproductive years and greater life expectancy. Conclusions Socioeconomic inequalities result in increased morbidity and decreased life expectancy. Interventions to reduce inequality and improve health in more deprived neighbourhoods have the potential to save money for health systems not only within years but across peoples’ entire lifetimes, despite increased costs due to longer life expectancies. PMID:27189975

  2. Incidence rates and life-time risk of hip fractures in Mexicans over 50 years of age: a population-based study.

    PubMed

    Clark, Patricia; Lavielle, Pilar; Franco-Marina, Francisco; Ramírez, Esperanza; Salmerón, Jorge; Kanis, John A; Cummings, Steven R

    2005-12-01

    The vast majority of hip fractures in the 21st century will occur in the developing countries. The rates and life-time hip fracture risk are not known for Mexico, and for this reason, we studied the incidence of hip fractures, and the remaining life-time probability of having a hip fracture at the age of 50 years in Mexican men and women. All hip fracture cases registered during the year 2000 were collected at all the main tertiary-care hospitals in the two major health systems in México City, Instituto Mexicano del Seguro Social (IMSS) and Ministry of Health (SS), and the diagnosis was validated by chart review in all cases. The annual rates of hip fracture were 169 in women and 98 in men per 100,000 person-years. The life-time probability of having a hip fracture at 50 years of age was 8.5% in Mexican women and 3.8% in Mexican men. We conclude that hip fractures are an important health problem in Mexico and that Mexican health authorities should consider public health programs to prevent hip fractures.

  3. Experimental Studies on Behaviour of Reinforced Geopolymer Concrete Beams Subjected to Monotonic Static Loading

    NASA Astrophysics Data System (ADS)

    Madheswaran, C. K.; Ambily, P. S.; Dattatreya, J. K.; Ramesh, G.

    2015-06-01

    This work describes the experimental investigation on behaviour of reinforced GPC beams subjected to monotonic static loading. The overall dimensions of the GPC beams are 250 mm × 300 mm × 2200 mm. The effective span of beam is 1600 mm. The beams have been designed to be critical in shear as per IS:456 provisions. The specimens were produced from a mix incorporating fly ash and ground granulated blast furnace slag, which was designed for a compressive strength of 40 MPa at 28 days. The reinforced concrete specimens are subjected to curing at ambient temperature under wet burlap. The parameters being investigated include shear span to depth ratio (a/d = 1.5 and 2.0). Experiments are conducted on 12 GPC beams and four OPCC control beams. All the beams are tested using 2000 kN servo-controlled hydraulic actuator. This paper presents the results of experimental studies.

  4. Study of transverse density waves in an electron beam experiment

    NASA Astrophysics Data System (ADS)

    Bernal, Santiago

    1999-10-01

    The physics of the transport of intense charged-particle beams is characterized by the evolution of the beam particle distribution in phase space. The internal structure of an intense beam, which comprises both density and temperature profiles, changes in response to the combined action of external focusing and the self- electric field. The present work explores beam evolution in experiments conducted in a number of focusing channels over a distance of about one meter. The initial experiments with one short solenoid and five printed- circuit (PC) magnetostatic quadrupole lenses constitute prototype matching experiments for the University of Maryland Electron Ring, or UMER. The latter will be a machine designed to explore beam physics issues associated with circular machines, over an entirely new regime of beam intensities with potential applications for future accelerators. In all experiments, the beam profiles along the channel are obtained from phosphor screen pictures. A linear beam envelope code is used for section design, while particle- in-cell simulations provide important clues for beam evolution. During the course of the initial matching experiments, a wavelike phenomenon was discovered that led to additional experiments in three-solenoid and six- PC quadrupole channels. It was found that the waves are induced by an aperture located a few centimeters from the electron gun cathode. Simulations suggest that the beam phase-space particle distribution relaxes to an equilibrium distribution after a few plasma periods. Furthermore, a simple particle-tracking model reproduces well the onset of the perturbation in all experiments. Simulations also show a small decrease of beam root-mean- square emittance, a beam quality factor, over a few plasma periods. Furthermore, the irreversible character and associated entropy increase of the beam relaxation are reconciled with the reduction in emittance. Several questions remain concerning the stability and scaling of the

  5. Analog detection for cavity lifetime spectroscopy

    DOEpatents

    Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

    2001-05-15

    An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

  6. Analog detection for cavity lifetime spectroscopy

    DOEpatents

    Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

    2003-01-01

    An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

  7. Improved Determination of the Neutron Lifetime

    NASA Astrophysics Data System (ADS)

    Yue, A. T.; Dewey, M. S.; Gilliam, D. M.; Greene, G. L.; Laptev, A. B.; Nico, J. S.; Snow, W. M.; Wietfeldt, F. E.

    2013-11-01

    The most precise determination of the neutron lifetime using the beam method was completed in 2005 and reported a result of τn=(886.3±1.2[stat]±3.2[syst])s. The dominant uncertainties were attributed to the absolute determination of the fluence of the neutron beam (2.7 s). The fluence was measured with a neutron monitor that counted the neutron-induced charged particles from absorption in a thin, well-characterized Li6 deposit. The detection efficiency of the monitor was calculated from the areal density of the deposit, the detector solid angle, and the evaluated nuclear data file, ENDF/B-VI Li6(n,t)He4 thermal neutron cross section. In the current work, we measure the detection efficiency of the same monitor used in the neutron lifetime measurement with a second, totally absorbing neutron detector. This direct approach does not rely on the Li6(n,t)He4 cross section or any other nuclear data. The detection efficiency is consistent with the value used in 2005 but is measured with a precision of 0.057%, which represents a fivefold improvement in the uncertainty. We verify the temporal stability of the neutron monitor through ancillary measurements, allowing us to apply the measured neutron monitor efficiency to the lifetime result from the 2005 experiment. The updated lifetime is τn=(887.7±1.2[stat]±1.9[syst])s.

  8. Measuring lifetimes of long-lived charged massive particles stopped in LHC detectors.

    PubMed

    Asai, Shoji; Hamaguchi, Koichi; Shirai, Satoshi

    2009-10-02

    Long-lived charged massive particles (CHAMPs) appear in various particle physics models beyond the standard model. In this Letter, we discuss the prospects for studying the stopping and decaying events of such long-lived CHAMPs at the LHC detectors, and show that the lifetime measurement (and the study of decay products) is possible with the LHC detectors for a wide range of the lifetime O(0.1)-O(10(10)) sec, by using periods of no pp collision. Even a short lifetime of order 1 sec can be measured by (i) identifying the stopping event with the on-line event filter, (ii) immediately making a beam-dump signal which stops the pp collision of the LHC, and at the same time (iii) changing the trigger menu to optimize it for the detection of a CHAMP decay in the calorimeter. Other possibilities are also discussed.

  9. Lifetime measurements in 162Dy

    NASA Astrophysics Data System (ADS)

    Aprahamian, A.; Lesher, S. R.; Casarella, C.; Börner, H. G.; Jentschel, M.

    2017-02-01

    Background: The nature of oscillations or excitations around the equilibrium deformed nuclear shape remains an open question in nuclear structure. The 162Dy nucleus is one of the most extensively studied nuclei with the (n ,γ ), (n ,e- ), (α ,2 n ) reactions and most recently the (p ,t ) pickup reaction adding 11 0+ states to an excitation energy of 2.8 MeV to an already-well-developed level scheme. However, a major shortfall for a better understanding of the nature of the plethora of bands and levels in this nucleus has been the lack of lifetime measurements. Purpose: To determine the character of the low-lying excited bands in this 162Dy nucleus, we set out to measure the level lifetimes. Method: Lifetimes were measured in the 162Dy nucleus following neutron capture using the Gamma-Ray-Induced Doppler (GRID) broadening technique at the Institut Laue-Langevin in Grenoble, France. Results: In total, we have measured the lifetimes of 12 levels belonging to a number of excited positive- and negative-parity bands in the low-lying spectrum of the 162Dy nucleus. The lifetime of the Kπ=2+ bandhead at 888.16 keV was previously measured. We confirm this value and measure lifetimes of the 3+ and 4+ members of this band yielding B (E 2 ) values that are consistent with a single γ -vibrational phonon of several Weisskopf units. The first excited Kπ=4+ band, with a bandhead at 1535.66 keV, is strongly connected to the Kπ=2+ band with enhanced collective B (E 2 ) values and it is consistent with a double phonon vibrational (γ γ ) excitation. Lifetime of Kπ=0+ band members have also been measured, including the 4Kπ=02+ state at 1574.29 keV and the 2Kπ= 03+ state at 1728.31 keV. This latter state also displays the characteristics of a double phonon excitation built on the Kπ=2+ band. Conclusions: We discuss our findings in terms of the presence or absence of collective quadrupole and octupole vibrational excitations. We find two positive-parity excited bands at 1535

  10. Performance Studies of the Vibration Wire Monitor on the Test Stand with Low Energy Electron Beam

    NASA Astrophysics Data System (ADS)

    Okabe, Kota; Yoshimoto, Masahiro; Kinsho, Michikazu

    In the high intensity proton accelerator as the Japan Proton Accelerator Research Complex (J-PARC) accelerators, serious radiation and residual dose is induced by a small beam loss such a beam halo. Therefore, diagnostics of the beam halo formation is one of the most important issues to control the beam loss. For the beam halo monitor, the vibration wire monitor (VWM) has a potential for investigating the beam halo and weak beam scanning. The VWM has a wide dynamic range, high resolution and the VWM is not susceptible to secondary electrons and electric noises. We have studied the VWM features as a new beam-halo monitor on the test stand with low energy electron gun. The frequency shift of the irradiated vibration wire was confirmed about wire material and the electron beam profile measured by using the VWM was consistent with the results of the Faraday cup measurement. Also we calculated a temperature distribution on the vibration wire which is irradiated by the electron beam with the numerical simulation. The simulations have been fairly successful in reproducing the transient of the irradiated vibration wire frequency measured by test stand experiments. In this paper, we will report a result of performance evaluation for the VWM on the test stands and discuss the VWM for beam halo diagnostic

  11. Studies on space charge neutralization and emittance measurement of beam from microwave ion source

    SciTech Connect

    Misra, Anuraag; Goswami, A.; Sing Babu, P.; Srivastava, S.; Pandit, V. S. E-mail: vspandit12@gmail.com

    2015-11-15

    A 2.45 GHz microwave ion source together with a beam transport system has been developed at VECC to study the problems related with the injection of high current beam into a compact cyclotron. This paper presents the results of beam profile measurement of high current proton beam at different degrees of space charge neutralisation with the introduction of neon gas in the beam line using a fine leak valve. The beam profiles have been measured at different pressures in the beam line by capturing the residual gas fluorescence using a CCD camera. It has been found that with space charge compensation at the present current level (∼5 mA at 75 keV), it is possible to reduce the beam spot size by ∼34%. We have measured the variation of beam profile as a function of the current in the solenoid magnet under the neutralised condition and used these data to estimate the rms emittance of the beam. Simulations performed using equivalent Kapchinsky-Vladimirsky beam envelope equations with space charge neutralization factor are also presented to interpret the experimental results.

  12. A study into lowering beam trajectories in P01

    SciTech Connect

    Sondgeroth, A.

    1995-09-01

    This document describes what changes would be needed to lower the primary beams coming from switchyard into enclosure P01 without changing trajectories in the downstream enclosures. There is a 680 foot pipe buried in the ground between Enclosure E and P01 which allows primary beam to travel from the switchyard area to the research division area. This pipe is approximately 25 years old and has started to leak. The effects of the leaky pipe can be catastrophic to the transportation of the proton area beams. The vacuum group has devised an ingenious way of repairing a leak from the inside using remotely controlled grinders, patchers, welders and cameras mounted on carts that can be pulled into the pipe. A typical patch adds approximately one half of an inch of material which, in turn, restricts the aperture of the pipe. This pipe has three separate beams running through it split in the vertical plane. Pwest is the highest beam in the pipe and, in at least one location, the center of the beam clears the top of the pipe by one and one half inches. If a leak were to develop at a low spot in the pipe the patch to fix the leak might create an obstruction for the beam. Hence, the request from the Research Division Head.

  13. Heritability of lifetime ecstasy use.

    PubMed

    Verweij, Karin J H; Treur, Jorien L; Vreeker, Annabel; Brunt, Tibor M; Willemsen, Gonneke; Boomsma, Dorret I; Vink, Jacqueline M

    2017-09-01

    Ecstasy is a widely used psychoactive drug that users often take because they experience positive effects such as increased euphoria, sociability, elevated mood, and heightened sensations. Ecstasy use is not harmless and several immediate and long term side effects have been identified. Lifetime ecstasy use is likely to be partly influenced by genetic factors, but no twin study has determined the heritability. Here, we apply a classical twin design to a large sample of twins and siblings to estimate the heritability of lifetime ecstasy use. The sample comprised 8500 twins and siblings aged between 18 and 45 years from 5402 families registered at the Netherlands Twin Registry. In 2013-2014 participants filled out a questionnaire including a question whether they had ever used ecstasy. We used the classical twin design to partition the individual differences in liability to ecstasy use into that due to genetic, shared environmental, and residual components. Overall, 10.4% of the sample had used ecstasy during their lifetime, with a somewhat higher prevalence in males than females. Twin modelling indicated that individual differences in liability to lifetime ecstasy use are for 74% due to genetic differences between individuals, whereas shared environmental and residual factors explain a small proportion of its liability (5% and 21%, respectively). Although heritability estimates appeared to be higher for females than males, this difference was not significant. Lifetime ecstasy use is a highly heritable trait, which indicates that some people are genetically more vulnerable to start using ecstasy than others. Copyright © 2017. Published by Elsevier B.V.

  14. A study on the forced vibration of a Timoshenko beam

    NASA Technical Reports Server (NTRS)

    Zainea, B.

    1976-01-01

    By using Galerkin's variational method an approximate solution is developed for a system of two differential equations with linear partial derivatives of the second order. This system of differential equations corresponds to the physical model, known in the literature as the Timoshenko Beam. The results obtained are applied to two particular cases representing respectively: the case of a beam with a rectangular section, with a constant height and a basis with a linear variation; and the case of a beam with a constant basis and a height with cubic variation.

  15. Beam discharge excited by distributed virtual cathode

    SciTech Connect

    Barabanov, V. N.; Dubinov, A. E.; Loiko, M. V.; Saikov, S. K.; Selemir, V. D.; Tarakanov, V. P.

    2012-02-15

    A new type of beam discharge, i.e., beam discharge with a distributed virtual cathode (VC) is proposed and considered by numerical simulation. The discharge is established during counter motion of high-current electron beams in a gas-filled equipotential cavity and is characterized by a state of hot dense electron plasma of primary electrons. The discharge temporal dynamics is studied. It is shown that the VC lifetime depends linearly from this sum in a wide range of the sum of beam currents, from the boundary current of two-beam instability to the critical current of Pierce instability. Generation of nonlinear electrostatic structures shaped as phase bubbles in the discharge is detected, and their dynamics is studied. The parameters are determined, at which the multiple coexistence of phase bubbles and their coalescence during collisions is observed.

  16. Nuclear Astrophysics and Structure Studies Using Low-energy RI Beams at CRIB

    SciTech Connect

    Yamaguchi, H.; Hashimoto, T.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kubono, S.

    2010-05-12

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Using the RI beams at CRIB, Many measurements on proton and alpha resonance scatterings, (alpha,p) reactions, and others were peformed in recent years, mainly for studying astrophysical reactions and exotic nuclear structure. Among them, the results on the {sup 7}Be+p and {sup 7}Li+alpha resonance scatterings are presented.

  17. Fluorescence lifetime attachment LIFA

    NASA Astrophysics Data System (ADS)

    van der Oord, Cornelius J. R.; Stoop, Karel W. J.; van Geest, Lambertus K.

    2001-05-01

    We present the Lambert Instruments Fluorescence Lifetime Attachment LIFA. LIFA enables easy to use and affordable microscopy and macroscopic FLIM. The system implements the homodyne detection scheme for measuring the fluorescence lifetime in each pixel of the image. The microscopy system features an ultra bright LED illuminator, the LI-(mu) Cam intensified CCD camera a high frequency signal generator. The illuminator replaces the excitation light source of a standard fluorescence microscopy, while the LI-(mu) CAM intensified CCD camera is attached to the photo-port. Both the illuminator and the intensifier are modulated at a frequency up to 100 MHz at a series of phase differences. The lifetime image is calculated from the series of images on a personal computer.

  18. Performance studies of four-dimensional cone beam computed tomography

    NASA Astrophysics Data System (ADS)

    Qi, Zhihua; Chen, Guang-Hong

    2011-10-01

    Four-dimensional cone beam computed tomography (4DCBCT) has been proposed to characterize the breathing motion of tumors before radiotherapy treatment. However, when the acquired cone beam projection data are retrospectively gated into several respiratory phases, the available data to reconstruct each phase is under-sampled and thus causes streaking artifacts in the reconstructed images. To solve the under-sampling problem and improve image quality in 4DCBCT, various methods have been developed. This paper presents performance studies of three different 4DCBCT methods based on different reconstruction algorithms. The aims of this paper are to study (1) the relationship between the accuracy of the extracted motion trajectories and the data acquisition time of a 4DCBCT scan and (2) the relationship between the accuracy of the extracted motion trajectories and the number of phase bins used to sort projection data. These aims will be applied to three different 4DCBCT methods: conventional filtered backprojection reconstruction (FBP), FBP with McKinnon-Bates correction (MB) and prior image constrained compressed sensing (PICCS) reconstruction. A hybrid phantom consisting of realistic chest anatomy and a moving elliptical object with known 3D motion trajectories was constructed by superimposing the analytical projection data of the moving object to the simulated projection data from a chest CT volume dataset. CBCT scans with gantry rotation times from 1 to 4 min were simulated, and the generated projection data were sorted into 5, 10 and 20 phase bins before different methods were used to reconstruct 4D images. The motion trajectories of the moving object were extracted using a fast free-form deformable registration algorithm. The root mean square errors (RMSE) of the extracted motion trajectories were evaluated for all simulated cases to quantitatively study the performance. The results demonstrate (1) longer acquisition times result in more accurate motion delineation

  19. On Monte Carlo modeling of megavoltage photon beams: A revisited study on the sensitivity of beam parameters

    SciTech Connect

    Chibani, Omar; Moftah, Belal; Ma, C.-M. Charlie

    2011-01-15

    Purpose: To commission Monte Carlo beam models for five Varian megavoltage photon beams (4, 6, 10, 15, and 18 MV). The goal is to closely match measured dose distributions in water for a wide range of field sizes (from 2x2 to 35x35 cm{sup 2}). The second objective is to reinvestigate the sensitivity of the calculated dose distributions to variations in the primary electron beam parameters. Methods: The GEPTS Monte Carlo code is used for photon beam simulations and dose calculations. The linear accelerator geometric models are based on (i) manufacturer specifications, (ii) corrections made by Chibani and Ma [''On the discrepancies between Monte Carlo dose calculations and measurements for the 18 MV Varian photon beam,'' Med. Phys. 34, 1206-1216 (2007)], and (iii) more recent drawings. Measurements were performed using pinpoint and Farmer ionization chambers, depending on the field size. Phase space calculations for small fields were performed with and without angle-based photon splitting. In addition to the three commonly used primary electron beam parameters (E{sub AV} is the mean energy, FWHM is the energy spectrum broadening, and R is the beam radius), the angular divergence ({theta}) of primary electrons is also considered. Results: The calculated and measured dose distributions agreed to within 1% local difference at any depth beyond 1 cm for different energies and for field sizes varying from 2x2 to 35x35 cm{sup 2}. In the penumbra regions, the distance to agreement is better than 0.5 mm, except for 15 MV (0.4-1 mm). The measured and calculated output factors agreed to within 1.2%. The 6, 10, and 18 MV beam models use {theta}=0 deg., while the 4 and 15 MV beam models require {theta}=0.5 deg. and 0.6 deg., respectively. The parameter sensitivity study shows that varying the beam parameters around the solution can lead to 5% differences with measurements for small (e.g., 2x2 cm{sup 2}) and large (e.g., 35x35 cm{sup 2}) fields, while a perfect agreement is

  20. Luminescence techniques and characterization of the morphology of polymer latices 2. Fluorescence lifetime, phosphorescence and fluorescence anisotropy studies.

    PubMed

    Soutar, I; Swanson, L; Annable, T; Padget, J C; Satgurunathan, R

    2006-11-01

    Five poly(n-butyl methacrylate), PBMA, latex dispersions have been prepared, each incorporating a different fluorescent label, via a two-stage seeded emulsion polymerization. The resultant latices contain ca. 35% by weight total solids and are of 80 (+/-10) nm diameter as determined by photon correlation spectrometry. Luminescence spectroscopic techniques, namely fluorescence (and phosphorescence) excited state lifetime measurements in addition to time-resolved anisotropy experiments have provided useful information regarding the morphology, microviscosity and water permeability of the resultant particles. A picture of the PBMA colloid emerges of an interior which is highly viscous and water impermeable in nature. Indeed, the environment is protective enough to sustain room temperature stabilized phosphorescence from both an acenaphthylene and 9-phenanthrylmethyl methacrylate labeled dispersion through simple nitrogen purging of the solutions. However, the current spectroscopic measurements should be viewed with the knowledge that each luminescent label may fashion its own distinctive microenvironment within the latex during polymerization.